MD Malo Le Hanneur
email: malo.lehanneur@gmail.com

MD Manon Colas

MD Julien Serane-Fresnel

MD Laurent Lafosse

MD Amaury Grandjean

MD Jonathan Silvera

MD Thibault Lafosse

MD L E Hanneur

Endoscopic brachial plexus neurolysis in the management of infraclavicular nerve injuries due to glenohumeral dislocation

Keywords: Brachial plexus, infraclavicular, neurolysis, release, endoscopy, arthroscopy, shoulder, glenohumeral, joint, dislocation pronator teres, FCR: flexor carpi radialis, PL: palmaris longus, FPL: flexor pollicis longus

ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

INTRODUCTION

With an incidence rate varying from 11.6 to 80.5 cases per 100,000 persons per year, anterior dislocation of the glenohumeral joint (GHJ) is a rather common injury, predominantly affecting young and active patients [START_REF] Shah | Incidence of shoulder dislocations in the UK, 1995-2015: a population-based cohort study[END_REF][START_REF] Perron | Acute complications associated with shoulder dislocation at an academic Emergency Department[END_REF] . In 5.4 to 55% of cases, concomitant palsy of the brachial plexus (BP) or one of its terminal branches may occur [START_REF] Gutkowska | Brachial plexus injury after shoulder dislocation: a literature review[END_REF] . Considering that such complications severely worsen patients' functional prognosis and that the risk of permanent nerve damages depends on the delay of reduction, initial physical examination of patients suffering from GHJ dislocation should primarily focus on neurological lesions [START_REF] Gleeson | Anterior glenohumeral dislocations: what to do and how to do it[END_REF][START_REF] Marsalli | Shoulder Terrible Triad: Classification, Functional Results, and Prognostic Factors[END_REF] .

Due to their anatomic location, all infraclavicular BP terminal branches may be affected, including from most to least frequently involved the axillary, ulnar, median, radial and musculocutaneous nerves [START_REF] Robinson | Injuries associated with traumatic anterior glenohumeral dislocations[END_REF][START_REF] Gutkowska | Analysis of Patient-Dependent and Trauma-Dependent Risk Factors for Persistent Brachial Plexus Injury after Shoulder Dislocation[END_REF] ; if such BP palsies are incomplete in the majority of cases, several terminal branches are most commonly involved, corresponding to cord lesions (i.e., anteromedial, anterolateral and posterior cords) [START_REF] Liveson | Nerve lesions associated with shoulder dislocation; an electrodiagnostic study of 11 cases[END_REF][START_REF] Visser | Electromyographic findings in shoulder dislocations and fractures of the proximal humerus: comparison with clinical neurological examination[END_REF][START_REF] Fox | The terrible triad of the shoulder[END_REF][START_REF] Hems | Injuries of the terminal branches of the infraclavicular brachial plexus: patterns of injury, management and outcome[END_REF][START_REF] Atef | Prevalence of associated injuries after anterior shoulder dislocation: a prospective study[END_REF] . With the combination of traction and compression forces, grade-I to grade-V lesions may be encountered, even if neurotmesis lesions appear to be rather uncommon [START_REF] Fox | The terrible triad of the shoulder[END_REF][START_REF] Hems | Injuries of the terminal branches of the infraclavicular brachial plexus: patterns of injury, management and outcome[END_REF][START_REF] Sunderland | Nerves and nerve injuries[END_REF][START_REF] Seddon | Three types of nerve injury[END_REF][START_REF] Burge | Patterns of injury to the terminal branches of the brachial plexus. The place for early exploration[END_REF] .

Since spontaneous recovery is observed in most cases, numerous authors tend to consider these lesions as benign and advocate for non-operative managements [START_REF] Gutkowska | Brachial plexus injury after shoulder dislocation: a literature review[END_REF][START_REF] Hems | Injuries of the terminal branches of the infraclavicular brachial plexus: patterns of injury, management and outcome[END_REF][START_REF] Kosiyatrakul | Recovery of brachial plexus injury after shoulder dislocation[END_REF][START_REF] Dhar | Anterior dislocation of shoulder with brachial plexus injury[END_REF] .

However, very long periods of time can be observed between the initial trauma and full recovery, with permanent distal deficits requiring palliative surgeries in most severe cases [START_REF] Kosiyatrakul | Recovery of brachial plexus injury after shoulder dislocation[END_REF] . Furthermore, if nerve reconstruction is not indicated to obtain satisfactory outcomes in most palsies resulting from axonotmesis lesions, neurotmesis lesions should be repaired as soon as possible to improve chances of recovery [START_REF] Fox | The terrible triad of the shoulder[END_REF] , and early differentiation between these two types of lesions cannot be made without surgical exploration in some cases [START_REF] Burge | Patterns of injury to the terminal branches of the brachial plexus. The place for early exploration[END_REF] .

With the recent advances in shoulder arthroscopic surgery, standardized procedures have been described to perform extensive dissections outside of the glenohumeral joint and

MATERIALS AND METHODS

Population Criteria. All patients who were referred to our institution from November 2017 to August 2019 in the setting of post-traumatic BP palsy due to GHJ dislocation were included. Patients who demonstrated significant clinical signs of spontaneous recovery within 6 weeks following the initial trauma were excluded from the study.

Preoperative management. A comprehensive initial physical examination was conducted in order to assess the muscular strengths of each muscle of the affected upper limb and compare those to the contralateral side, using the British Medical Research Council (BMRC) grading system. Monofilament testing was conducted upon both upper limbs as well, grading the cutaneous sensitivity of the different nerve territories from 0 (i.e., anesthesia -no sensitivity) to 2 (i.e., normal sensitivity -symmetric to the unaffected side), with grade-1 sensitivity corresponding to hypoesthesia (i.e., protection sensitivity). At the end of examination, motor and sensitive deficits were synthetized and classified in nerve and/or cord lesions (Table 1). In order to maintain passive ranges of motion and stimulate paralyzed muscles, a rehabilitation program was established at the end of consultation, associating standard and neuropathic pain medications, self-rehabilitation postural maneuvers and physiotherapy sessions.

Six weeks after the trauma, physical examination was repeated in order to decide whether or not the patient would undergo arthroscopic BP neurolysis. In cases of satisfactory clinical recovery, defined as grade-4 or higher muscular strength and grade-1 or higher sensitivity in all the initially affected nerve territories, non-operative management was elected; rehabilitation was resumed and clinical follow-up was conducted every 3 months until full recovery was yielded. In patients demonstrating insufficient clinical recovery (i.e., ≤ grade-3 strength and/or grade-0 sensitivity), an electrophysiological (EDX) study and a BP magnetic resonance imaging (MRI) scan were conducted to confirm the palsy extent that had been clinically assessed and look for prognostic information (e.g., denervation and/or reinnervation potentials on the EDX study; muscular denervation changes and/or intraneural edema on the MRI scan). The MRI scan included the ipsilateral shoulder to assess potential associated osteoarticular and/or musculotendinous lesions. Several criteria were taken into account to select either a conservative or an operative approach, including the clinical extent and severity of the deficit, the course of clinical recovery, as well as the EDX and MRI data (Figure 1). When patients were referred lately to our institution (i.e., more than 6 weeks after the dislocation), assessment of the course of clinical recovery was based on data retrieved from medical reports of the previous institution(s).

Surgical technique.

With the patient set up in a beach chair position axial traction applied upon the upper limb, surgery was performed under general anesthesia without locoregional anesthesia. All patients were operated on by the senior author, using the technique previously described by Lafosse et al. [START_REF] Lafosse | All-endoscopic Brachial Plexus Complete Neurolysis for Idiopathic Neurogenic Thoracic Outlet Syndrome: Surgical Technique[END_REF] .

Briefly, a posterior portal was first created in the shoulder soft point to enter the scope in the GH joint, allowing the assessment and management of articular and/or tendinous lesions. An instrumental anterolateral portal was then created in the rotator interval, which was developed using an electrocautery probe. Dissection was resumed outside of the joint by creating successive additional portals, medial to the shoulder, under scopic visualization. The retropectoral and subclavicular spaces were developed to expose the infraclavicular BP, using the coracoid process, the conjoint tendon and the upper border of the pectoralis minor as landmarks. The axillary artery was used to identify the different cords (i.e., anterolateral, anteromedial and posterior). The subclavius muscle and the pectoralis minor tendon were then transected to expose the infraclavicular BP terminal branches, including the musculocutaneous, median, ulnar, radial and axillary nerves. The latter were released from any soft-tissue adhesions until they reached the retrocoracoid space, so that their aspect and continuity could be assessed under scopic magnification.

Postoperative care. The patient was discharged the day after surgery once active bleeding and/or significant blood loss were ruled out by systematic postoperative blood count.

The upper limb was placed in a sling for 2 days to limit the risk of hematoma; after that, immobilization was removed and the patient was told to use the operated arm as much as possible for all daily living activities. As soon as postoperative pain and swelling decreased, usually within the week following surgery, rehabilitation was resumed using the same protocol as preoperatively.

Two weeks after surgery, patients were seen in clinics to check on surgical wounds and rehabilitation observance. If neurotmesis lesions were identified during endoscopic exploration, secondary nerve transfers were subsequently scheduled at this time. Otherwise, physical examinations, as described above, were conducted at 6 weeks, 3 months and 6 months after surgery in order to assess postoperative clinical recovery. An independant observer retrieved all pre-and postoperative data, as well as intraoperative findings. In all cases, patients benefited from GHJ reduction at other centers and were referred to our institution secondarily. Subsequently, the characteristics of the dislocation (e.g., date and type of GHJ dislocation, side of injury, delay between GHJ dislocation and reduction, need of general anesthesia for GHJ reduction) were retrieved from the medical reports of these previous centers. For clarity purpose, all motor deficits observed in a nerve and/or cord territory during pre-and postoperative examinations were summarized to a single BMRC grade per territory; since surgical indication was based on the most severe deficit, the lowest grade was used. Similar synthesis was conducted for sensitive deficits, using the lowest sensitivity grade observed in the affected upper limb to summarize the sensitivity of the entire limb.

RESULTS

Series Characteristics. Twenty patients met our inclusion criteria. Among them, nine patients completely recovered within 6 weeks following GHJ dislocation and were subsequently excluded from the study; no patient was lost during follow-up. Regarding the 11 remaining patients, 6 were male and 5 were female, with a mean age of 43 ± 23 years (16;73) at the time of trauma.

All patients had suffered from a first episode of anteroinferior GHJ dislocation, which involved the right shoulder in 7 cases. Before undergoing endoscopic BP exploration, 6 patients had incomplete palsies involving at least one cord, 4 had an isolated palsy of the axillary nerve and the last patient had a complete palsy of the infraclavicular BP. With 6 patients who were referred lately to our institution, a mean preoperative delay of 111 ± 77 days (46;301) was observed between the initial trauma and the release surgery; details of patients' preoperative characteristics are presented in Table 2.

Surgical Findings. During GHJ exploration, degenerative posterosuperior rotator cuff tears were identified in 2 patients; since none of them complained of shoulder functional limitations before the dislocation, no attempt of repair was undertaken. In one patient, a traumatic avulsion fracture of the greater tuberosity was identified (i.e., equivalent of shoulder terrible triad); however, due to late referral (i.e., more than 9 months), cuff retraction up to the glenoid neck level as well as spinati muscles fatty infiltration were identified on the preoperative MRI scan; subsequently, no attempt of repair was undertaken.

In all cases, severe adhesions were found outside of the anterior and medial aspects of the glenohumeral joint, sheathing the infraclavicular BP and/or its terminal branches.

Precautious and progressive dissection allowed exposing all cords and nerves in all patients.

In 2 patients presenting with an isolated palsy of the axillary nerve, neurotmesis lesions (i.e., Sunderland grade-V lesions) were identified; in a third patient with similar clinical presentation on initial examination, the axillary nerve appeared to be very damaged under scopic magnification and felt "empty" when palpated with the smooth end of an arthroscopic switching stick. No intraoperative or postoperative complications were reported.

Clinical Outcomes. Based on the observed outcomes following endoscopic BP neurolysis, three groups of patients could be distinguished, as outlined in Table 3.

In 7 patients (i.e., group A), clinical improvements were observed in all the affected nerves and/or cords within 6 weeks following the neurolysis, with at least grade-3 strength noted in all muscles (Table 4). These patients demonstrated at least grade-4 strength in all muscles after 3 months of follow-up, and all but one yielded full recovery, both motor and sensitive, within 6 months after the neurolysis. Due to late referral, the patient with persistent deficits at the 6-months follow-up visit had undergone arthroscopic BP neurolysis almost 10 months after GHJ dislocation (Patient 7 -Table 4). If shoulder and elbow functions completely recovered, lesser grip strength was noted in the affected hand than in the contralateral hand on Jamar testing; since she did not complain about any functional limitations, no additional procedures were performed towards the hand.

In 3 patients (i.e., group B), the endoscopic BP exploration led to schedule early double nerve transfers to reanimate the axillary nerve anterior branch and the teres minor motor branch, using triceps brachii motor branches through an axillary approach [START_REF] Lafosse | Double-Nerve Transfer to the Axillary Nerve in Traumatic Upper Trunk Brachial Plexus Injuries Using an Axillary Approach: Anatomical Description and Preliminary Case Series[END_REF] . Regarding the two patients with neurotmesis lesions, nerve transfers were performed within a month following the neurolysis procedure. The last case was performed in a patient who had been referred lately to our institution (i.e., 102 days), suffering from complete palsies of both the deltoid and teres minor muscles with no signs of recovery on initial clinical examination; as previously stated, severe axillary nerve damages were noted under scopic magnification.

After 3 months of follow-up, considering postoperative clinical improvements not satisfactory (i.e., grade-1 deltoid strength and grade-0 teres minor strength), a secondary double nerve transfer was elected. Intraoperatively, stimulation of the axillary nerve triggered a weak response in the deltoid and teres minor muscles; subsequently, end-to-side transfers were performed to both motor branches (i.e., supercharge transfers). Full recovery (i.e., grade-5 deltoid and teres minor strengths) was noted within 12 months following nerve transfers in all three patients.

In 1 patient presenting with a complete BP palsy on initial examination (i.e., group C), no postoperative improvements were observed within the first 6 months of follow-up, despite the absence of nerve ruptures and/or severe damages noticed during endoscopic exploration.

After 6 months, recovery started at the shoulder (i.e., grade-2 deltoid strength) and progressed distally towards the hand over 18 months. After 2 years of follow-up, at least grade-4 strength was observed in all muscles, with the exception of hand intrinsic muscles. Tendon transfers were subsequently performed, including Zancolli lassos to restore long fingers metacarpophalangeal joint flexion, extensor pollicis brevis to first palmar interosseous to reinforce the thumb-index pinch, and an extensor indicis proprius opponensplasty.

Secondary procedures. In addition to the nerve and tendon transfers previously exposed, 2 patients with irreparable posterosuperior rotator cuff tears underwent reverse shoulder arthroplasty, including one patient who had benefited from end-to-end nerve transfers of triceps motor branches to the axillary nerve, with grade-4 deltoid strength after 11 months of follow-up. Arthroplasties were performed after at least one year following the last procedure (i.e., endoscopic neurolysis or nerve transfer) for septic considerations and to favor deltoid reinforcement. Satisfactory outcomes were observed in both cases, with at least 120° and 30° of active shoulder flexion and external rotation, respectively.

DISCUSSION

In this study, we reported our strategy regarding the management of traumatic infraclavicular BP palsies following GHJ dislocation, based on early endoscopic BP neurolysis. If such procedure did not provide significant benefit to the natural course of recovery in one case, early and fast postoperative improvements were observed in 7 patients, yielding satisfactory function within 6 weeks after the surgery in all cases and complete recovery within 6 months in all patients but one. In addition, we were able to schedule early nerve transfers in patients with neurotmesis and/or severe axonotmesis lesions. However, several essential points still need to be clarified, starting with the very basis of such strategy.

Indication of early BP exploration. If the different characteristics of infraclavicular BP

palsies following GHJ dislocations are widely described, few authors proposed an explicit algorithm regarding the indication of surgical exploration [START_REF] Gutkowska | Brachial plexus injury after shoulder dislocation: a literature review[END_REF] . When considering the literature referring to other post-traumatic nerve injuries, several authors advocate for early neurolysis as the first step of surgical management [START_REF] Niver | Management of radial nerve palsy following fractures of the humerus[END_REF] . As an example, Keighley and colleagues, based on a complete recovery rate of 100% after 6 to 8 months of follow-up, recommended to perform systematic radial nerve releases in patients presenting radial nerve palsies secondary to middle and distal humerus fractures [START_REF] Keighley | Radial nerve palsy in mid/distal humeral fractures: is early exploration effective?[END_REF] . Similarly, in their series of 122 patients suffering from iatrogenic peripheral nerve lesions, Rasulic et al. observed 85.4% of satisfactory recovery in 48 patients who underwent nerve exploration within the first 6 months, against 67.6% in the 74 patients who were operated on after this delay [START_REF] Rasulic | Iatrogenic Peripheral Nerve Injuries-Surgical Treatment and Outcome: 10 Years' Experience[END_REF] .

If such attitude is not commonly adopted in cases of infraclavicular BP palsy due to GHJ dislocation, it is primarily related to the fact that, provided that a sufficiently long period of follow-up is respected, spontaneous recovery is more often observed in this particular type of post-traumatic palsies than in others [START_REF] Visser | Electromyographic findings in shoulder dislocations and fractures of the proximal humerus: comparison with clinical neurological examination[END_REF][START_REF] Takase | Concurrent rotator cuff tear and axillary nerve palsy associated with anterior dislocation of the shoulder and large glenoid rim fracture: a "terrible tetrad[END_REF][START_REF] De Laat | Nerve lesions in primary shoulder dislocations and humeral neck fractures. A prospective clinical and EMG study[END_REF][START_REF] Midha | Epidemiology of brachial plexus injuries in a multitrauma population[END_REF] . Except in cases of high-energy trauma and/or associated fractures, the risk of nerve rupture is low due to the blunt aspect of the humeral head as well as the anatomical characteristics of the infraclavicular BP (e.g., distant from the exit of the spinal cord, no anatomical fixation point) [START_REF] Burge | Patterns of injury to the terminal branches of the brachial plexus. The place for early exploration[END_REF][START_REF] Rathore | Fracture Dislocation of Shoulder with Brachial Plexus Palsy: A Case Report and Review of Management Options[END_REF][START_REF] Stenning | Low-energy arterial injury at the shoulder with progressive or delayed nerve palsy[END_REF] . Subsequently, very satisfactory complete recovery rates have been reported by different authors, varying from 75 to 100% [START_REF] Visser | Electromyographic findings in shoulder dislocations and fractures of the proximal humerus: comparison with clinical neurological examination[END_REF][START_REF] Kosiyatrakul | Recovery of brachial plexus injury after shoulder dislocation[END_REF][START_REF] Saragaglia | Acute anterior instability of the shoulder: short-and mid-term outcome after conservative treatment[END_REF] . However, the delays of recovery displayed in these studies could be rather significant, varying from a few weeks in patients with simple neurapraxia lesions to 23 months in patients with axonotmesis lesions [START_REF] Kosiyatrakul | Recovery of brachial plexus injury after shoulder dislocation[END_REF][START_REF] Saragaglia | Acute anterior instability of the shoulder: short-and mid-term outcome after conservative treatment[END_REF] . Furthermore, other authors noted that nerve reconstruction was required in only 13 to 18% of patients presenting such palsies, with preoperative delays most commonly superior than 3 months [START_REF] Hems | Injuries of the terminal branches of the infraclavicular brachial plexus: patterns of injury, management and outcome[END_REF][START_REF] Travlos | Brachial plexus lesions associated with dislocated shoulders[END_REF][START_REF] Leffert | Infraclavicular Brachial Plexus Injuries[END_REF] . In the present series, much shorter delays were observed, with grade-3 strength observed in all affected muscles within 6 weeks following the release in 7 patients with axonotmesis lesions. Moreover, in the 3 patients who required nerve reconstructions, the latter were performed within the first 3 months following the dislocation in all cases. Timing of surgery. Timing for surgical exploration remains controversial in posttraumatic nerve palsies, since the physician has to find the right compromise between allowing spontaneous nerve regeneration and preventing irreversible motor end plate losses with subsequent muscular atrophy [START_REF] Kline | Timing for brachial plexus injury: a personal experience[END_REF] . Accordingly, numerous studies recommended delaying surgical management at least 3 to 6 months after the initial trauma [START_REF] Travlos | Brachial plexus lesions associated with dislocated shoulders[END_REF][START_REF] Wehbe | Surgical treatment of traumatic lesions of the axillary nerve. A retrospective study of 33 cases[END_REF][START_REF] Kandenwein | Surgical interventions for traumatic lesions of the brachial plexus: a retrospective study of 134 cases[END_REF] , while others authors advised to avoid waiting more than 6 to 9 months [START_REF] Giuffre | Current concepts of the treatment of adult brachial plexus injuries[END_REF][START_REF] Limthongthang | Adult brachial plexus injury: evaluation and management[END_REF] . For example, Battiston and colleagues considered that the optimal interval between the trauma and operative intervention is 5.4 months [START_REF] Battiston | Traumatic brachial plexus injuries[END_REF] . However, early surgical exploration, undertaken within 3 months after the trauma, seems to be supported by a growing number of authors [START_REF] Gutkowska | Brachial plexus injury after shoulder dislocation: a literature review[END_REF][START_REF] Fox | The terrible triad of the shoulder[END_REF][START_REF] Battiston | Traumatic brachial plexus injuries[END_REF][START_REF] Birch | Surgical disorders of the peripheral nerves[END_REF] .

In this series, we respected an interval of 6 weeks to avoid operating on patients with neurapraxia and/or mild axonotmesis lesions who would have spontaneously recovered satisfactory function within a short period of time. Meanwhile, this also prevents from longlasting follow-up periods whose effects might be substantial in terms of social impact, which can be dramatic in young and active patients, but also in terms of motor end plate degeneration, which starts very early after the trauma [START_REF] Kobayashi | The effect of duration of muscle denervation on functional recovery in the rat model[END_REF] . Such short time frame for surgical exploration has already been proposed in cases of isolated axillary palsies without recovery within 2 months following the trauma, in order to look for nerve ruptures [START_REF] Hems | Injuries of the terminal branches of the infraclavicular brachial plexus: patterns of injury, management and outcome[END_REF] .

Underlying pathophysiology. Based on the work of Brown, early surgical nerve release has been assumed to avoid the occurrence of scar tissues surrounding otherwise healthy nerve fascicles, leading to further aggravation of clinical symptoms [START_REF] Brown | Internal Neurolysis in Treatment of Traumatic Peripheral Nerve Lesions[END_REF] . Following GHJ dislocations, in addition to the compression and traction axonal injuries directly related to the humeral head impact onto the infraclavicular BP, perineural adhesion formations develop from the post-traumatic hematoma, aggravating local BP compression and degrading its gliding properties [START_REF] Fox | The terrible triad of the shoulder[END_REF] . By excising the scar tissues, neurolysis recreates a more favorable environment for the nerves. In this series, clinical improvements were noticed in all patients from group A almost immediately after they woke up from surgery. Subjective improvements were major, with complete vanishing of the compression sensations at the proximal aspect of the arm and tremendous decrease of paresthesia that patients described preoperatively.

Moreover, very early sensitive and/or motor improvements were noticed as well in most cases, either immediately after surgery or at the 2-weeks follow-up consultation. We believe that this group of patients most probably suffered from "refractory" neurapraxia with mild axonotmesis lesions, which presentation was substantially worsened by the perineural fibrosis that was removed during surgery.

Although patients with neurotmesis lesions are rather rare [START_REF] Gutkowska | Analysis of Patient-Dependent and Trauma-Dependent Risk Factors for Persistent Brachial Plexus Injury after Shoulder Dislocation[END_REF][START_REF] Hems | Injuries of the terminal branches of the infraclavicular brachial plexus: patterns of injury, management and outcome[END_REF][START_REF] Dhar | Anterior dislocation of shoulder with brachial plexus injury[END_REF][START_REF] Travlos | Brachial plexus lesions associated with dislocated shoulders[END_REF] , such procedure is particularly beneficial to them since there is no chance to obtain any functional improvements without nerve reconstruction [START_REF] Burge | Patterns of injury to the terminal branches of the brachial plexus. The place for early exploration[END_REF] . Early ascertainment of nerve discontinuity thus allows performing nerve transfers in a very short time frame. Similarly, in cases of preserved nerve continuity, visualization of severe nerve damages during endoscopic exploration as well as the absence of early improvements despite a comprehensive nerve release are strong arguments for the physician to perform an early nerve reconstruction. The benefits of such early operative interventions include prevention of clinically significant end plate losses, alleviation of neuropathic pain and limitation of the risk of neuroma formation [START_REF] Gutkowska | Brachial plexus injury after shoulder dislocation: a literature review[END_REF] . In patients from group B, with all nerve reconstructions performed within 3 months following the initial trauma, full recovery was yielded within the first year following the nerve transfer.

Limitations of the technique.

In this series, one patient did not show any improvement following the neurolysis (i.e., group C). Functional improvements started 6 months after the trauma and a progressive recovery was observed over 18 months of follow-up, in a proximalto-distal fashion. We believe that this patient suffered from moderate axonotmesis lesions (i.e., Sunderland type-III lesions), which are, in our opinion, one of the primary limitations to this technique, especially when no obvious signs of damage are visible on the nerve superficial aspect. Indeed, since axonal regeneration is mandatory to allow satisfactory muscle activity, releasing perineural scar tissues is not sufficient to obtain early functional improvements [START_REF] Kosiyatrakul | Recovery of brachial plexus injury after shoulder dislocation[END_REF] . Furthermore, the superficial nerve sheath is most often preserved in such lesions, precluding the endoscopic identification of intraneural lesions [START_REF] Kline | Timing for brachial plexus injury: a personal experience[END_REF] .

Another limitation of this technique is its inherent technicality and the subsequent long learning curve that is required to perform it safely [START_REF] Lafosse | All-Endoscopic Resection of an Infraclavicular Brachial Plexus Schwannoma: Surgical Technique[END_REF][START_REF] Lafosse | All-endoscopic Brachial Plexus Complete Neurolysis for Idiopathic Neurogenic Thoracic Outlet Syndrome: Surgical Technique[END_REF][START_REF] Lafosse | All-Endoscopic Brachial Plexus Complete Neurolysis for Idiopathic Neurogenic Thoracic Outlet Syndrome: A Prospective Case Series[END_REF] . Since one of the main arguments supporting this procedure is its minimal morbidity, it is of primary importance that the surgeon performing it is experienced in both nerve surgery and shoulder endoscopic dissections conducted outside of the glenohumeral joint. In addition, due to extensive scar tissues and shoulder stiffness, BP neurolysis in such post-traumatic indications is rather difficult. Spaces between the conjoint tendon and pectoralis minor and/or between the conjoint tendon and the subscapularis were sometimes difficult to localize because of severe adhesions. In most of the cases, thick scar tissue surrounded the nerves and artery in front of the subscapularis. The greatest risk is to damage the axillary artery or one of its branches, thus resulting in bleeding that may be difficult to control. We would recommend extreme caution while performing the procedure; if any excessive technical difficulty is faced, endoscopy should be stopped and surgery should be resumed in an open fashion. Furthermore, endoscopic neurolysis has been previously used in nerve compression syndromes, such as suprascapular neuropathies and neurogenic thoracic outlet syndromes [START_REF] Lafosse | All-endoscopic Brachial Plexus Complete Neurolysis for Idiopathic Neurogenic Thoracic Outlet Syndrome: Surgical Technique[END_REF][START_REF] Lafosse | All-Endoscopic Brachial Plexus Complete Neurolysis for Idiopathic Neurogenic Thoracic Outlet Syndrome: A Prospective Case Series[END_REF][START_REF] Lafosse | Arthroscopic release of suprascapular nerve entrapment at the suprascapular notch: technique and preliminary results[END_REF] , as well as in benign tumoral cases [START_REF] Lafosse | All-Endoscopic Resection of an Infraclavicular Brachial Plexus Schwannoma: Surgical Technique[END_REF] . With the absence of any scar tissues and/or perineural adhesions, endoscopic dissection is relatively straightforward in these non-traumatic indications, and may thus be a more adequate option at the beginning of experience.

Finally, the main shortcoming of such endoscopic approach may lie in the very limited possibilities to perform anything else than the dissection itself. If intraneural dissection has been demonstrated feasible and successful [START_REF] Lafosse | All-Endoscopic Resection of an Infraclavicular Brachial Plexus Schwannoma: Surgical Technique[END_REF] , to the best of our knowledge, no nerve suture has been performed yet with the use of standard arthroscopic equipment, subsequently precluding direct repairs of neurotmesis lesions as well as nerve graft and transfer procedures.

With robotic assistance and customized equipment (e.g., needle holder, clamp, scissors forceps…), the feasibility of performing such microsurgical procedures endoscopically has been demonstrated in cadaveric experimentations [START_REF] Mantovani | Endoscopic exploration and repair of brachial plexus with telerobotic manipulation: a cadaver trial[END_REF] . However, the relevance of such expensive technology has yet to be proved in clinical practice, since open conversion was required in all patients who underwent robot-assisted BP reconstruction [START_REF] Garcia | Telerobotic manipulation of the brachial plexus[END_REF][START_REF] Facca | Robot-assisted surgery of the shoulder girdle and brachial plexus[END_REF] . Nonetheless, design of new microsurgical tools, based on those used with the Da Vinci robot but tailored to standard arthroscopic equipment, could be a potential way to further push the technical limits of this technique and subsequently increase its indications.

Limitations of the study. The main shortcoming of the study relies in the lack of a control group. Considering the rarity of such presentations, unquestionable statistical evidence seems unrealistic to yield in a monocentric study. Furthermore, due to the paucity of the existing literature, no gold-standard approach exists yet to be compared with. In addition, even though no statistical comparaison could be made due to smallness of our sample, the complete absence of clinical improvement that we observed in patients who were referred lately, despite several months of conservative treatment in some cases, contrasted with the very satisfactory outcomes that we noted very early after surgical management in the great majority of cases (i.e., 7 patients over 8 who did not need nerve reconstruction). Based on those outcomes, a multicentric prospective comparative trial is currently underway, in order to more precisely assess the potential benefits and limitations of such early surgical management in comparison with traditional conservative treatment. Finally, considering that the data were retrieved from the pre-and postoperative examinations of the operating surgeon, an observational bias cannot be excluded. Reverse shoulder arthroplasty * Strength was graded using the British Medical Research Council grading system; for clarity purpose, the grade reported in front of the nerve/cord corresponds to the grade of the most affected muscle innervated by this nerve/cord. Sensitivity was graded 0 (i.e., anesthesia), 1 (i.e., hypoesthesia) or 2 (i.e., normal sensitivity); for clarity purpose, the reported grade corresponds to the worst sensitivity that was observed in the cutaneous territory of the affected nerve/cord.

  Data collection. Before any data collection and/or analysis, the study was registered in the database register of the National Committee of Computer Science and Liberties (i.e., Commission Nationale de l'Informatique et des Libertés -CNIL; No 2217505 version 0). A retrospective chart review was then conducted in accordance with the ethical standards of the Declaration of Helsinki of 1964 and the Methodology of Reference MR-003 25 .

  sensitive deficits (i.e., hand / forearm involvement) OR ≤ Grade-0 strength in ≥ 1 muscle(s) OR No recovery after ≥ 6 weeks of follow-up OR Severe denervation signs / Mild reinnervation signs on the EDX study / MRI scan No Yes Endoscopic BP neurolysis Severely damaged / Ruptured nerves Satisfactory nerve aspect Rehabilitation Early nerve transfer

Table 1 .

 1 Definitions of the lesions.

	Neurological lesions *	Motor deficits

Table 2 .

 2 Series characteristics.

	Patients (No)

* Data are presented as mean ± standard deviation (interval), unless otherwise stated. No: number of cases/patients in absolutes values; Male: male; F: female; R: right; L: left.

Table 3 .

 3 Postoperative findings following arthroscopic brachial plexus neurolysis in the setting of brachial plexus palsy due to glenohumeral dislocation.

	Groups	Findings	Number of cases
	A	Early postoperative improvements	7
	B	Early indication for nerve transfer	3
	C	Absence of benefit	1

Table 4 .

 4 Characteristics of patient presenting early improvements following endoscopic brachial plexus neurolysis.

			Preoperative
	Patients	Initial presentation *	delay

expose the entire infraclavicular BP[START_REF] Lafosse | Brachial plexus endoscopic dissection and correlation with open dissection[END_REF][START_REF] Lafosse | All-Endoscopic Resection of an Infraclavicular Brachial Plexus Schwannoma: Surgical Technique[END_REF][START_REF] Lafosse | All-endoscopic Brachial Plexus Complete Neurolysis for Idiopathic Neurogenic Thoracic Outlet Syndrome: Surgical Technique[END_REF] . Using such techniques, comprehensive releases of all cords and terminal branches can be made, allowing the identification and treatment of potential nerve compression sites, perineural soft-tissue adhesions as well as intraneural lesions, at the cost of minimal surgical morbidity[START_REF] Lafosse | All-Endoscopic Resection of an Infraclavicular Brachial Plexus Schwannoma: Surgical Technique[END_REF][START_REF] Lafosse | All-endoscopic Brachial Plexus Complete Neurolysis for Idiopathic Neurogenic Thoracic Outlet Syndrome: Surgical Technique[END_REF][START_REF] Lafosse | All-Endoscopic Brachial Plexus Complete Neurolysis for Idiopathic Neurogenic Thoracic Outlet Syndrome: A Prospective Case Series[END_REF] .On the grounds of previously published literature[START_REF] Gutkowska | Brachial plexus injury after shoulder dislocation: a literature review[END_REF][START_REF] Burge | Patterns of injury to the terminal branches of the brachial plexus. The place for early exploration[END_REF][START_REF] Lafosse | Brachial plexus endoscopic dissection and correlation with open dissection[END_REF][START_REF] Lafosse | All-Endoscopic Resection of an Infraclavicular Brachial Plexus Schwannoma: Surgical Technique[END_REF][START_REF] Niver | Management of radial nerve palsy following fractures of the humerus[END_REF][START_REF] Keighley | Radial nerve palsy in mid/distal humeral fractures: is early exploration effective?[END_REF][START_REF] Rasulic | Iatrogenic Peripheral Nerve Injuries-Surgical Treatment and Outcome: 10 Years' Experience[END_REF] , we established a standardized algorithm to manage infraclavicular BP palsies secondary to GHJ dislocation, based on early endoscopic BP neurolysis. The purpose of this study was to assess the outcomes that such strategy could provide in patients showing no significant signs of spontaneous recovery within 6 weeks following the initial trauma.

CONCLUSIONS

In the setting of BP palsy due to GHJ dislocation, endoscopic BP neurolysis appears to be a safe and reliable procedure when performed by a shoulder surgeon experienced in periarticular endoscopic dissection. When performed early, substantial benefits were observed in the great majority of patients at the cost of minimal additional surgical morbidity.

Subsequently we believe that such procedure should be considered as an additional therapeutic option in the management of patients with BP palsy due to GHJ dislocation when no signs of early clinical improvement are observed.


Coil_W Coil_R

Coil_H Coil_W Coil_R

Magnet Mag_R

Magnet Mag_R Gap Mag_H Mag_W Coil

Keywords:

In this paper a two stage modelling, to ensure a good and fast optimization procedure for microdevices, is be presented. This methodology is supported by three non-commercial software. The first one is dedicated to analytical modelling of non ferromagnetic electromagnetic devices, the second one is dedicated to numerical modelling of electromagnetic devices, and the last is dedicated to constrained based optimization. Issues and solutions of such a methodology are highlighted, and illustrated by designing a matrix of actuators for an adaptive optic.

I. INTRODUCTION AND METHODOLOGY

Adaptive optic is based on a deformable reflector actuated by a matrix of electromagnetic actuators [START_REF] Cugat | Deformable magnetic mirror for adaptive optics: technological aspects[END_REF]. Each actuator is commanded separately and moves in real time the reflecting surface to balance atmosphere turbulence and avoid image deformations. Force of the initial device is 26 mN at Gap=0.5mm, the mass is equal to 18 mg. The aim of the design optimization is to improve actuators regarding actuating force (force at Gap=0.5mm must be 30mN) and magnet mass minimization.

To perform such a design, optimization procedure is required. Several strategies are available; the simplest is to optimize with direct calls to the numerical simulation solver, but it is a very expensive in terms of computational efforts; an other is to create a response surface from a numerical solver which is then optimized [START_REF] N'guessan | Comparison of two optimization strategies for the design of an ultrafast actuator[END_REF]. A third solution has been chosen for this study, which is also based on two level modeling and which can be seen as a manual manifold mapping technique [START_REF] Echeverria | On the Manifold-Mapping Optimization Technique[END_REF] including knowledge of the designer.

First modeling level is based on an analytical description of the device to perform the optimization, and then refining the solution with a second modeling level using a numerical solver that takes into account phenomena like magnetic demagnetization.

II. MODELING FORMULATIONS

A. Analytical formulation

Our analytical modeling is based on integral formulations which are symbolically solved for basic shapes [START_REF] Rakotoarison | Using Coulombian Approach for Modeling Scalar Potential and Magnetic Field of a Permanent Magnet With Radial Polarization[END_REF]. Other symbolic solutions, based on elliptic integrals can also be used [START_REF] Ravaud | Analytical calculation of the magnetic field created by permanentmagnet rings[END_REF]. Magnetic field produced by magnets is computed using Coulombian equivalent charge method; Biot and Savart law is applied for current sources. Forces and torques acting on magnets are computed using an equivalent surface charges method like electrostatic devices; Laplace law is used on conductors. Based on a magnetic components library and the application of superposition theorem, software has been developed to produce automatically this kind of analytical model from a geometrical and physical description [START_REF] Rakotoarison | Methodology and tool for generating semi-analytical models Used to pre-design electromagnetic MEMS (Mag-MEMS)[END_REF]. On the one hand, computation time of this kind of model is very short, which is important for an optimization process. Moreover, symbolic gradients are available, allowing very constrained design. On the other hand, this modeling lacks of accuracy. For example, magnet magnetization is homogenous and constant.

B. Numerical Method: Mixed FFEF-BEM Modeling

Our numerical solver is based on a Finite Formulation of Electromagnetic Fields (FFEF), coupled with integral boundary conditions based on magnetization integrals [START_REF] Giuffrida | Finite Formulation of nonlinear magneto-statics with integral boundary conditions[END_REF].

The method is based on the use of scalar global variables, obtained by integrating field variables on a double system of meshes, strictly connected by relations of duality. Global variables are distinguished in: Configuration Variables (CV) associated to the primal mesh and Source Variables (SV), associated to the dual one. CV involved in the actual study are magnetic ϕ fluxes on primal faces and circulation p, line integral of magnetic vector potential on primal edges. While SV are magnetomotive forces F (mmf) on dual edges and i Two levels modeling for the optimization of electromagnetic actuators B. Delinchant (+) , G. Gruosso (*) (Member IEEE), F. Wurtz (+) (Member IEEE) (+) G2ELab -Grenoble Electrical Engineering Lab, ENSE3, 38402 Grenoble, FRANCE (*) Politecnico di Milano-Dipartimento di Elettronica e Informazione, Piazza Leonardo da Vinci, 32-20133 Milano, Italy Benoit.Delinchant@inpg.fr -gruosso@elet.polimi.it current on dual faces. According with [START_REF] Giuffrida | Finite Formulation of nonlinear magneto-statics with integral boundary conditions[END_REF] the topological equations are the following :

{ } { } ϕ = p C] [ (6) { } {} i F C = ] [ (7)
being ] [C and ] [C curl matrices on primal and dual complex, respectively. The constitutive equation is:

{ } { } M F R F - = ϕ ν ] [ ] [ (8)
where ν ] [R is the reluctance matrix, that takes into account the magnetic anisotropy, and M F is the mmf due to magnetization sources on dual edges.

The solution of the previous equations requires a proper set of boundary conditions. This fact requires the discretization of the air surrounding the analyzed device. In order to limit the discretization of the problem to its ferromagnetic part only, the presented hybrid formulation adds some integral terms to the equations for the relations of the primal edges lying on the boundary of the ferromagnetic part. Thus inner edges and boundary ones have to be treated in different way. For each inner edge an equation can be written by imposing the satisfaction of Ampere law on the contour of the dual face associated to it. For outer edges it is not possible to write an equation of the same type, because there is no associated dual face contained as whole inside the domain. Thus exterior part of the integration path can be efficiently treated by a magnetic scalar potential difference as:

- = ⋅ b a b a dl H ) ( ) ( ψ ψ (9)
where a and b are the points where the dual face contour intersects the mesh boundary.

An integral equation can be written for the external part of the domain as:

0 ) ' , ( ) ' ( ) ' , ( ) ' ( ) ( = ∂ ∂ + ∂ ∂ - dS G dS G S S ψ ψ αψ ( 10
)
Where is α constant which is equal to π if point lies on a plane surface and ) ' , ( G is the free space Green function. By starting from this formulation the force calculation has been performed by means of Maxwell stress tensor. This method is usually considered critic, in particular, the value coming out of the integration of Maxwell tensor can be affected by a large error when the integration surface crosses the finite element mesh due to local inaccuracies of computed values of magnetic flux density. As it was pointed out in [START_REF] Ren | Force calulation by Maxwell stress tensor in 3D hybrid finite element -boundary element integral formulation[END_REF], this problem can be overcome by the use of hybrid techniques where magnetic field is obtained by integral formulas whose accuracy is largely independent of the mesh structure.

This modeling has been used to overcome some hypothesis of the previous one, including for example the demagnetization of the hard magnetic material.

III. OPTIMIZATION STRATEGY

A. Simple optimization on the analytical model

Optimization over the analytical model, to achieve design requirements, does not work without some safety measures.

Indeed, it will be shown that optimizer goes, most of time, out of the model validity domain. It is possible to constrain parameters to stay in a restricted area, but these constraints are artificial and then optimal solution too. At first stage an optimisation with a constraint limiting the solution to the range of validity has be done in the CADES framework [START_REF] Delinchant | An optimizer using the software component paradigm for the optimization of engineering systems[END_REF]. The parameter meaning and their variation range is reported in Tab.I. The objective of the optimization are:

• Volumic force optimization (to improve reactivity during regulation of micro mirrors) • Nominal force is constrained to be equal to 0.03 N • Magnet aspect ratio in constrained to be < 1 (magnet high > magnet width) In Fig. 3 the configuration before and after the optimization is reported. The objective is obtained reaching the good force value but the maximal value of the aspect ratio, creating an artificial optimal solution (fig. 4). It is possible to see, from the numerical simulation, as the demagnetization of the magnet takes a significant role in the determination of the force (fig. 5). Under these hypotheses the value of the calculate force is 27.8 mN different from the desidered value of 30 mN.

B. Optimization without validity limitation

In order to avoid the artificial solution obtained in the previous case, the solution is to try to relax constraints to see where the algorithm converge and if it is far from our artificial limit of the form factor = 1. At this stage the objectives and constraints are: In fig. 6 the optimal configuration is shown together with the parameter variation versus iteration number.

We can see that magnet form factor (aspect ratio) converge to an optimal value of 2.64 (fig. 7) , moreover, there is no hole inside the magnet leading to a real form factor of 2.65 x 2 = 5.3 which is probably too big regarding demagnetization effect. We have to check if our modeling is good in such a configuration thanks to an other modeling techniques including demagnetization curve of the magnet. The computed force in this condition is equal to 27 mN. This is the proof that our optimization is false due to the magnetization effect that is neglected in the analytical model (fig. 8).

C. A Strategy to overcome such artificial constraints

How to use our optimization model knowing that the optimal solution is out of the range of validity ?

A good solution is to use manifold mapping technique but it requires to make both models computable automatically, and implementing the mathematical algorithm in a supervisor, which is not currently our case.

A quick solution is then proposed including the knowledge of the designer on the domain restriction of its modeling. The solution consists of plotting a curve of optimal configurations for several value of a parameter representing the modeling hypothesis rightness (in our case : magnet aspect ration)

The technique used to plot such a curve is based on a set of optimizations where Magnet aspect ration is constrained to a fixed value from 1 to 3 by steps of 0.25 (9 automated sequential optimizations). It is automated thanks to the CADES optimization framework [START_REF] Delinchant | An optimizer using the software component paradigm for the optimization of engineering systems[END_REF]. It takes 40 iterations (20 minutes). For each optimal configuration, a simulation is run to check rightness.

Magnet aspect ration value (mm)

Fig. 9. Set of optimal design versus magnet aspect ratio.

The numerical modeling curve shows a displacement of the optimal point to better aspect ratio giving a good optimal solution regarding demagnetization effect. Indeed, even if demagnetization has an effect, the structure of micro-actuators gives an optimal solution with an aspect ratio of about 2.25.

We can notice that optimal solution of part B (aspect ratio = 2.64) is defined when magnet radius (Mag_R) reach zero.

As it can be seen on fig. 10 that real force decrease when analytical model trusts on a constant value of 30 mN. This decrease is a proof that magnet aspect ratio is a good criteria for the estimation of rightness of the analytical model.

Magnet aspect ration force (mN)

Analytical Force FFEF Force This figure shows also a difference of 2.67 mN between analytical and numerical model at the optimal magnet aspect ration founded before. This difference has to be cancelled to reach the real design specifications.

A final optimization is then performed to adjust the force with a kind of manual manifold mapping technique. This optimization tries to reach a force constrained to a compensated value of 30+2.67 mN.

Only 4 iterations are required to converge to the desired force, giving the final optimal configuration in fig 11. This solution has been simulated with the fine model, computing a force of 30mN with a maximal volumic force of 12.1 mN/mm 3 . IV. CONCLUSIONS

In this study, a methodology using two level modeling and optimization tool was demonstrated on an simple application. This methodology can be applied on more complex systems, even with several axis of hypothesis where curve as to be changed by n-dimensional plots.

It is based on knowledge about electromagnetic hypothesis of modeling. Indeed, design has to find the parameter which characterize the modeling hypothesis of coarse model (analytic one here) Such strategies need fast modeling (coarse model), coupled with optimization algorithm and an accurate model (simulation tool) to check some specific configurations.

Fig. 1 .

 1 Fig. 1. Optical system and actuator creating mirror micro displacement

Fig. 2 .

 2 Fig. 2. Software generating an analytical model from a parameterized geometry and physic [6].

Fig. 3 .Fig. 4 .

 34 Fig. 3. Configuration before and after constrained optimization

Fig. 5 .

 5 Fig.5. Effect of demagnetization simulated using numerical method (Tesla)

•Fig. 6 .

 6 Fig. 6. Optimal configuration and parameter variation during optimization

Fig. 7 .

 7 Fig. 7. Volumic force and aspect ratio versus iteration number

Fig. 8 .

 8 Fig. 8. Demagnetization versus radius in the optimized configuration

Fig. 10 .

 10 Fig. 10. Force for the set of optimal configuration.

Fig. 11 .

 11 Fig. 11. Convergence to the optimal configuration


Julie Delvallée

Lauranne Rossard

Sofiane Bendifallah

Cyril Touboul

Pierre Collinet

Alexandre Bricou

Cyrille Huchon

Vincent Vincent Lavoue

Gilles Body

Lobna Ouldamer
email: l.ouldamer@chu-tours.fr

Accuracy of peritoneal carcinomatosis extent diagnosis by initial FDG PET CT in epithelial ovarian cancer: A multicentre study of the FRANCOGYN research group

niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

1

Introduction

Ovarian cancer (OC) is the seventh leading cause of female cancer with 4,615 new cases in 2012 and 3,140 deaths in France. In parallel with the aging population, the incidence of ovarian cancer has also been increasing [START_REF]Les données -Institut National Du cancer[END_REF][START_REF] Invs | estimation des cancers en[END_REF]. The average age of diagnosis is approximately 63 years old [START_REF]Les données -Institut National Du cancer[END_REF]. The most important risk factor for ovarian cancer is genetic: about 10% of ovarian cancers occur in a context of genetic predisposition (mainly BRCA 1/2 mutation) and then occur before the age of 60 years. Unlike for breast or colon cancer, there is no organised screening programme, because no diagnostic test is sufficiently sensitive and specific for the detection of OC especially at an early-stage.

The majority of ovarian cancers are of the epithelial type (90%). Other types, includes stromal tumours (granulosa/sex cords) and germ cell tumours [START_REF] Frère-Belda | Encyclopédie Médico Chirurgicale -Gynécologie -Classification histopathologique des tumeurs ovariennes[END_REF]. Since diagnosis is often late, three quarters of these cancers are diagnosed at an advanced stage (stages IIIB to IV). Its prognosis remains poor. 5-year overall survival, all stages combined, is approximately 45% with poorer prognosis for stages III and IV (between 20-40% and around 10%, respectively) [START_REF]Les données -Institut National Du cancer[END_REF][START_REF] Musto | Management of epithelial ovarian cancer from diagnosis to restaging: an overview of the role of imaging techniques with particular regard to the contribution of 18F-FDG PET/CT[END_REF].

The diagnostic approach, in case of discovery of a pelvic mass, includes performing abdominal and pelvic ultrasounds, determining serum tumour marker levels (CA 125, CA 19-9 and ACE) and thoracic-abdominal-pelvic computerised tomography (CT) to characterise the lesion. This exploration can be completed to determine the mass and extent of lesions by pelvic imaging such as MRI (Magnetic Resonance Imaging) or 2-[18F]-fluoro-2-deoxy-Dglucose (FDG)-positron-emission tomography (PET) CT according to ASCO recommendations (5). The standard evaluation is based on surgical staging as recommended by the International Federation of Gynaecology and Obstetrics (FIGO).

The primary surgery must be a complete cytoreduction surgery with no macroscopic residual disease whenever feasible because it determines the patient 's survival: a residual tumour <1 cm is associated with a worse prognosis when compared to surgery without macroscopic residual disease [START_REF] Musto | Management of epithelial ovarian cancer from diagnosis to restaging: an overview of the role of imaging techniques with particular regard to the contribution of 18F-FDG PET/CT[END_REF][START_REF] Lee | Prognostic value of preoperative intratumoral FDG uptake heterogeneity in patients with epithelial ovarian cancer[END_REF][START_REF] Gallicchio | F-18 FDG PET/CT metabolic tumour volume predicts overall survival in patients with disseminated epithelial ovarian cancer[END_REF]. PET CT appears sensitive using the Standardised Uptake Value (SUV) to diagnose peritoneal carcinomatosis or the presence of lymphatic or visceral metastases [START_REF] Lopez-Lopez | Use of (18)F-FDG PET/CT in the preoperative evaluation of patients diagnosed with peritoneal carcinomatosis of ovarian origin, candidates to cytoreduction and hipec. A pending issue[END_REF][START_REF] Ohliger | PET/MR Imaging in Gynecologic Oncology[END_REF][START_REF] Xu | Diagnostic value of positron emission tomography (PET) and PET/computed tomography in recurrent/metastatic ovarian cancer: A meta-analysis[END_REF], but the initial assessment of disease extension remains difficult since the tumour volume is hard to assess and is still performed during exploratory laparoscopy [START_REF] Lee | Prognostic value of preoperative intratumoral FDG uptake heterogeneity in patients with epithelial ovarian cancer[END_REF].

The main objective of the present study was to evaluate the diagnostic reliability of FDG PET CT for peritoneal carcinomatosis extent in epithelial ovarian cancer (EOC), performed before any treatment and to compare it with peroperative observations/ histology samples obtained during upfront laparotomy/ laparoscopy in the setting of a multicentre study.

Material and methods

Patients

We conducted a retrospective study using maintained databases from 7 French referral gynaecologic oncology institutions from a research group network. The databases registered all patients diagnosed with ovarian cancer at any stage between January 2000 and December 2016. The research protocol was approved by our Institutional Review Board.

Inclusion

All patients treated for EOC, who underwent FDG PET CT at the beginning of management, were included, irrespective of whether the surgical treatment was a frontline cytoreduction surgery or a laparoscopy followed by neoadjuvant chemotherapy. Please note that all PET CTs were performed with 18 Fluorodeoxyglucose (18 FDG). The extension of peritoneal carcinomatosis was given by peroperative findings/ histological results in case of frontline cytoreductive surgery or peroperative findings of exploratory laparoscopy. For lymph node involvement, it was analysed only in women who underwent lymphadenectomy.

Exclusion criteria: All patients who did not undergo surgery at diagnosis be it laparotomy with cytoreductive surgery or an exploratory laparoscopy before chemotherapy.

Procedures

All patients underwent clinical examination. Preoperative workup included at least a PET CT and for most of them a standard abdominal -pelvic computed tomography scan (CT -scan).

PET images were obtained using a combined 16-section PET/computed tomography (CT) camera 60 minutes following the intravenous injection, with 2 minutes per bed position. The field of view was the whole body. CT images were obtained with contrast media injection and interpreted by experienced radiologists.

Experienced nuclear physicians in each participant centre independently estimated FDG uptake while blinded to the clinical characteristics of each subject.

PET images were classified as positive if there was focal or multifocal FDG uptake and negative if there was no uptake or residual physiological FDG uptake. A quantitative analysis was also performed, in which a maximum standardised uptake value (SUVmax) All surgeries were performed by a qualified gynaecologic oncologist. Initial management consisted in explorative surgery (laparoscopy) to confirm the diagnosis, determine the extent of the peritoneal spread and the resectability of the disease. Decision to proceed to either primary frontline cytoreductive surgery or neoadjuvant chemotherapy followed by interval debulking surgery was at the discretion of the surgeon. This decision was based on the extent of the disease, surgical experience and on patient comorbidities and the ability to withstand a radical procedure. Cytoreductive surgeries were always performed with intent to achieve no macroscopic residual disease. It included at least a midline laparotomy, total hysterectomy, bilateral salpingo -oophorectomy and infragastric omentectomy. A more extensive surgery was performed when indicated and could involve digestive tract resections, upper abdominal resections such as diaphragmatic resection, splenectomy, lymph node dissection and any other gesture to obtain no residual disease.

The initial stage of the disease was determined according to the classification of the International Federation of Gynaecology and Obstetrics (FIGO) and TNM seventh edition [START_REF]Gynécologie et d'Obstétrique -Classification des tumeurs de l'ovaire[END_REF][START_REF] Kurman | WHO classification of tumors of ovary[END_REF].

In order to obtain an exhaustive collection, the histological types of ovarian tumours collected were those described by WHO [START_REF] Frère-Belda | Encyclopédie Médico Chirurgicale -Gynécologie -Classification histopathologique des tumeurs ovariennes[END_REF][START_REF] Kurman | WHO classification of tumors of ovary[END_REF].

Statistical analysis

Descriptive parameters were expressed as the mean (± Standard Deviation [SD]) and median

[range] when indicated. Frequencies were presented as percentages. Demographic, clinical, biological, and radiological characteristics are summarised by continuous variables and categorical variables and were analysed using the Student's test.

For continuous variables, we used t-tests. Overall survival time was calculated in months from the date of diagnostic to death or the date of last follow-up for surviving patients. The Kaplan-Meier method was used to estimate the survival distribution. Patients alive at the endpoint have been censored. Effects were expressed as hazard ratios (HRs) with 95%confidence intervals as appropriate. A p-value of <0.05 was considered statistically significant. Data were managed in an Excel database (Microsoft, Redmond, WA, USA) and analysed using software R 3.1.2 Package Hmisc, Design and Survival libraries [START_REF]Logiciel R version 3.1.2 (package Hmisc, Design and Survival libraries[END_REF].

Results

During the study period, 980 women were treated for an epithelial ovarian cancer within our research group centres. Ninety patients (9.2%) were included in the present study and received a PET CT scan before surgery or any treatment.

The characteristics of the study population are summarised in Table 1.

At diagnosis, 80% of the patients had advanced stage III or IV disease (47 and 25 patients respectively). There were nine cases (10%) where the stage was not specified but described as locally advanced (III or IV). Table 2.

Regarding the management, 3 patients did not have cytoreductive surgery but only one or more laparoscopies (3/90 or 3.3%), 41 patients underwent frontline cytoreductive surgery (41/90 i.e. 45.6%) followed on average by 4 courses of adjuvant chemotherapy. Thirty-two patients underwent interval surgery considered as complete (35.6%) and 14 were operated on interval surgery considered as incomplete (15.5%). On average, the number of neo-adjuvant courses was 4.

In our population, epithelial ovarian tumours were mostly serous (66/90, 73.3%), endometrioid (8/90, 8.9%) and undifferentiated adenocarcinoma (8/90, 8.9%).

To differentiate ovarian, unilateral or bilateral involvement, PET CT was reliable for the serous type in 69.6% of the cases, for the mucinous type in 66.6% and for the endometrioid type in 66.7% of the cases. For an extension to the cupola, PET CT was reliable in 57.1% for the serous type. For omentum invasion, the prediction was 66.7% for the mucinous type and 48.1% for the serous type. Small intestine disease was confirmed in 75% of cases for the endometrioid, 75% for the mucinous 75% and 47.5% for the serous type. The involvement of the colon was found in 87.5% of the cases for the endometrioid, 75% for the mucinous and 58% for the serous types. For the serous type, there were 53 cases of high grade, and 5 low grade.

The prediction accuracy of peritoneal carcinomatosis on the initial PET by comparing the histological data of the surgical specimens is presented on table 3 There was no link between the value of CA 125 and the reliability of PET CT.

Eighty patients had a standard CT scan at diagnosis that was evaluated for diagnostic reliability and compared to PET CT. The accuracy of prediction of peritoneal carcinomatosis extent on the initial CT is presented on table 4 The mean follow-up in our population was 28 months (1-342). Overall survival for the entire population was 60% at 5 years.

Discussion

The aim of our study was to evaluate the diagnosis reliability of PET CT for peritoneal carcinomatosis extent in EOC, performed before any treatment and to compare it with histology samples obtained during laparotomy and/ or per-operative observations during laparoscopy in the framework of a multicentre study conducted by the FRANCOGYN research group.

EOC prognosis is strongly related to its local and regional extension: the FIGO and TNM classifications take into account peritoneal carcinomatosis in staging [START_REF]Les données -Institut National Du cancer[END_REF][START_REF] Invs | estimation des cancers en[END_REF]. Tumours without peritoneal carcinomatosis may be considered to be at lower risk of recurrence taking into account tumour volume and abdominopelvic extension. In addition, size and capsular rupture of lymph nodes are important prognostic factors significantly associated with both overall and recurrence-free survival [START_REF]Les données -Institut National Du cancer[END_REF][START_REF] Musto | Management of epithelial ovarian cancer from diagnosis to restaging: an overview of the role of imaging techniques with particular regard to the contribution of 18F-FDG PET/CT[END_REF][START_REF] Gallicchio | F-18 FDG PET/CT metabolic tumour volume predicts overall survival in patients with disseminated epithelial ovarian cancer[END_REF][START_REF] Rosen | The impacts of neoadjuvant chemotherapy and of debulking surgery on survival from advanced ovarian cancer[END_REF][START_REF] Vergote | Neoadjuvant chemotherapy or primary surgery in stage IIIC or IV ovarian cancer[END_REF].

According to the European Society for Medical Oncology (ESMO), PET CT is not recommended for the initial management of EOC [START_REF] Ledermann | Newly diagnosed and relapsed epithelial ovarian carcinoma: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up[END_REF]. The recommendations of the American Society of Cancerology and Oncology (ASCO) regarding the evaluation of peritoneal carcinomatosis and the neoadjuvant chemotherapy response, unchanged since then, are:

-The initial evaluation is based on imaging with injected time, if possible abdominal-pelvic CT with chest sections in order to evaluate any possible diaphragmatic extension, in order to specify tumour involvement, laparoscopic evaluation may be considered or second-line imaging such as PET CT or pelvic MRI, -Histological evidence of ovarian origin should be provided, failing that the follow-up will be performed on the fluctuations of CA 125 and the ratio CA 125 / ACE: a value greater than 25 evokes a gynaecological origin (20).

The French recommendations (HAS) remain vague concerning the indication of PET CT in this context, it evokes it in the pre-therapeutic assessment in case of a disease difficult to characterise or when NAC is scheduled. In his meta-analysis, Lee shows that CT scans are a good tool for evaluating tumour mass during preoperative evaluation and that the value of hypermetabolism is associated with early recurrence [START_REF] Lee | Prognostic value of preoperative intratumoral FDG uptake heterogeneity in patients with epithelial ovarian cancer[END_REF]. These data are included in the study by Klumpp et al, which preoperatively evaluated the location and extent of peritoneal carcinomatosis, but this study concerned a very small population (n = 15), suggesting a probable reading of the images by only one professional [START_REF] Klumpp | Preoperative assessment of peritoneal carcinomatosis: intraindividual comparison of 18F-FDG PET/CT and MRI[END_REF]. This examination can be used as part of protocols, within nomograms, for the prediction of incomplete cytoreduction [START_REF] Shim | Nomogram for predicting incomplete cytoreduction in advanced ovarian cancer patients[END_REF][START_REF] Risum | Positron emission tomography/computed tomography predictors of overall survival in stage IIIC/IV ovarian cancer[END_REF]. The combination of abdominopelvic CT / PET CT provides the best assessment of carcinomatosis extent, although surgical exploration allows the most reliable findings with possible pathological confirmation [START_REF] Pfannenberg | F-FDG-PET/CT to select patients with peritoneal carcinomatosis for cytoreductive surgery and hyperthermic intraperitoneal chemotherapy[END_REF].

PET CT is a recent nuclear imaging technique with good sensitivity (Se) and specificity (Sp)

for the diagnosis of peritoneal carcinomatosis extent, reported at around 90% for both parameters in the literature [START_REF] Klumpp | Preoperative assessment of peritoneal carcinomatosis: intraindividual comparison of 18F-FDG PET/CT and MRI[END_REF][START_REF] Kim | Peritoneal carcinomatosis in patients with ovarian cancer: enhanced CT versus 18F-FDG PET/CT[END_REF]. The strength of this imaging technique lies in its positive predictive value (PPV) greater than 95% and a correct negative predictive value (NPV) close to 75%. These data are concordant with the meta-analysis of Limei in 2013, although the diagnosis performance is heterogeneous according to the studies [START_REF] Limei | Accuracy of Positron Emission Tomography/Computed Tomography in the Diagnosis and Restaging for Recurrent Ovarian Cancer: A Meta-Analysis[END_REF]. The results are similar in the meta-analysis by Li in 2015 with a Specifity greater than 85% and a Sensitivity close to 95% [START_REF] Li | Comparison of PET with PET/CT in detecting peritoneal carcinomatosis: a meta-analysis[END_REF]. Thus, these two meta-analyses tend to define PET CT as a good diagnostic tool for peritoneal carcinomatosis extent diagnosis, without separating the initial diagnosis and recurrence situations. Diagnosis accuracy is reported to be close to 90% in both of these studies, Suppiah et al's meta-analysis reported in 2017 a value of 87% [START_REF] Suppiah | Systematic Review on the Accuracy of Positron Emission Tomography/Computed Tomography and Positron Emission Tomography/Magnetic Resonance Imaging in the Management of Ovarian Cancer: Is Functional Information Really Needed?[END_REF].

PET CT are presented as imaging that can be used to abstain from interval laparoscopic reevaluation in the case of NAC when detecting peritoneal carcinomatosis implants less than 2 cm in size and positive lymph nodes or persistent diaphragmatic lesions [START_REF] Suppiah | Systematic Review on the Accuracy of Positron Emission Tomography/Computed Tomography and Positron Emission Tomography/Magnetic Resonance Imaging in the Management of Ovarian Cancer: Is Functional Information Really Needed?[END_REF]. The study by De Iaco, which concerned peritoneal carcinomatosis -all comers -highlights a good correlation between PET CT and surgical exploration for lesions greater than 5 mm, with no interest in metastatic lymphadenopathy [START_REF] De Iaco | FDG-PET/CT in advanced ovarian cancer staging: value and pitfalls in detecting lesions in different abdominal and pelvic quadrants compared with laparoscopy[END_REF]. These data are to be taken with caution since the authors are equally interested in peritoneal carcinomatosis during the initial diagnosis and during recurrence, on digestive pathologies with a significant proportion of male patients mixing different cancers and situations.

By combining data from two different situations, the prediction of lesions artificially increases as well as the Sensitivity and Specificity of the examination. In addition, the definition of peritoneal carcinomatosis was multimodal and does not rely solely on PET CT: it contrasts with other imaging or histological analysis or operative findings [START_REF] Lee | Prognostic value of preoperative intratumoral FDG uptake heterogeneity in patients with epithelial ovarian cancer[END_REF][START_REF] Limei | Accuracy of Positron Emission Tomography/Computed Tomography in the Diagnosis and Restaging for Recurrent Ovarian Cancer: A Meta-Analysis[END_REF][START_REF] Suppiah | Systematic Review on the Accuracy of Positron Emission Tomography/Computed Tomography and Positron Emission Tomography/Magnetic Resonance Imaging in the Management of Ovarian Cancer: Is Functional Information Really Needed?[END_REF].

The advantage of PET CT lies in the diagnosis of diaphragmatic localisations and metastatic recurrence, at an undeveloped stage since all parasitic signals are excluded and only implants linked to the disease are visualised [START_REF] Suppiah | Systematic Review on the Accuracy of Positron Emission Tomography/Computed Tomography and Positron Emission Tomography/Magnetic Resonance Imaging in the Management of Ovarian Cancer: Is Functional Information Really Needed?[END_REF][START_REF] Schmidt | Peritoneal carcinomatosis in primary ovarian cancer staging: comparison between MDCT, MRI, and 18F-FDG PET/CT[END_REF][START_REF] Rubini | Peritoneal carcinomatosis from ovarian cancer: role of 18F-FDG-PET/CT and CA125[END_REF][START_REF] Chung | Prognostic implication of the metastatic lesion-to-ovarian cancer standardised uptake value ratio in advanced serous epithelial ovarian cancer[END_REF]. This detection capacity seems to increase with the CA 125 level and when the conventional imaging techniques are taken in default: identification of the areas of interest [START_REF] Thrall | Clinical use of combined positron emission tomography and computed tomography (FDG-PET/CT) in recurrent ovarian cancer[END_REF]. However, in the previously mentioned metaanalyses, neither pelvic lymph node nor para-aortic involvement was assessed [START_REF] Lee | Prognostic value of preoperative intratumoral FDG uptake heterogeneity in patients with epithelial ovarian cancer[END_REF][START_REF] Limei | Accuracy of Positron Emission Tomography/Computed Tomography in the Diagnosis and Restaging for Recurrent Ovarian Cancer: A Meta-Analysis[END_REF][START_REF] Suppiah | Systematic Review on the Accuracy of Positron Emission Tomography/Computed Tomography and Positron Emission Tomography/Magnetic Resonance Imaging in the Management of Ovarian Cancer: Is Functional Information Really Needed?[END_REF].

The correlation between the size measured in PET CT and the histological size varies according to the tumour phenotype [START_REF] García | F-FDG PET/CT as predictor of tumour biology and prognosis in epithelial ovarian carcinoma[END_REF]. Thus, SUVs are lower for ovarian mucinous cancers than digestive tumours but with higher diffusion coefficients [START_REF] Schwenzer | Measurement of apparent diffusion coefficient with simultaneous MR/positron emission tomography in patients with peritoneal carcinomatosis: comparison with 18F-FDG-PET[END_REF][START_REF] Konishi | Maximum standardized uptake value of fluorodeoxyglucose positron emission tomography/computed tomography is a prognostic factor in ovarian clear cell adenocarcinoma[END_REF]. In our study, the correlation was better for the endometrioid and mucinous types, which is consistent with the studies on digestive neoplasia but is contradictory for the serous type. In the literature, the histological type influences SUVs: values are higher for serous or endometrioid profiles.

PET CT in the context of the NAC make it possible to evaluate the efficacy of the treatment, and to guide the clinician in evaluating the tumour residue at the end of treatment [START_REF] Khiewvan | An update on the role of PET/CT and PET/MRI in ovarian cancer[END_REF].

Regarding surgical management, primary surgery with adjuvant chemotherapy appears to improve the overall survival of patients compared to a NAC [START_REF] Rosen | The impacts of neoadjuvant chemotherapy and of debulking surgery on survival from advanced ovarian cancer[END_REF][START_REF] Gill | Optimizing the treatment of ovarian cancer: Neoadjuvant chemotherapy and interval debulking versus primary debulking surgery for epithelial ovarian cancers likely to have suboptimal resection[END_REF][START_REF] Melamed | Trends in the use of neoadjuvant chemotherapy for advanced ovarian cancer in the United States[END_REF]. The major criterion, however, remains the presence of a macroscopic residual disease [START_REF] Braicu | Preoperative HE4 expression in plasma predicts surgical outcome in primary ovarian cancer patients: results from the OVCAD study[END_REF].

The strength of our study lies in its multicentre nature and the number of patients included.

However, we cannot rule out inherent retrospective bias. The first cytoreduction or NAC indications were at the discretion of the surgeon in each centre and may represent a recruitment bias. However, all participating centres are regional reference centres that apply French / European standards after discussion in multidisciplinary consultation committee.

During the data collection period, there was little change in the classifications (FIGO and TNM) and in the surgical techniques (digestive resection, resection or peritoneal fulguration).

On the other hand, the PET technique and especially the machines used are constantly evolving: this results in a better current definition of lesions. In older studies, lesions could be "forgotten" because of insufficient detection. Current machines tend to cuts of smaller thickness but still thicker than those of CT [START_REF] Nougaret | Ovarian carcinomatosis: how the radiologist can help plan the surgical approach[END_REF].

The sensitivity and specificity values of our study may appear low compared to recent metaanalyses as shown in table 5 [START_REF] Klumpp | Preoperative assessment of peritoneal carcinomatosis: intraindividual comparison of 18F-FDG PET/CT and MRI[END_REF][START_REF] Limei | Accuracy of Positron Emission Tomography/Computed Tomography in the Diagnosis and Restaging for Recurrent Ovarian Cancer: A Meta-Analysis[END_REF][START_REF] Li | Comparison of PET with PET/CT in detecting peritoneal carcinomatosis: a meta-analysis[END_REF][START_REF] Suppiah | Systematic Review on the Accuracy of Positron Emission Tomography/Computed Tomography and Positron Emission Tomography/Magnetic Resonance Imaging in the Management of Ovarian Cancer: Is Functional Information Really Needed?[END_REF]. Our endpoint was stricter: initial assessment of peritoneal carcinomatosis extent for an epithelial ovarian tumour, without defining minimum detection size and excluding digestive causes and other causes of peritoneal carcinomatosis.

In the end, the diagnosis of peritoneal carcinomatosis is often obtained by histological samples taken during surgery since the imaging techniques are often inaccurate for lesions of small sizes.

Conclusion

The rates of false positives and false negatives in PET CT and abdominopelvic CT are not negligible rendering laparoscopy a mandatory tool to evaluate the extent of peritoneal carcinomatosis in case of advanced epithelial ovarian cancer. PET CT does not seem to be the most efficient test for assessing the initial tumour extent. We should prefer abdominal-pelvic CT as indicated in the current French recommendations. This test is better than the clinical examination and abdominal-pelvic ultrasound to assess the extent of the disease, with a lower price and shorter examination time and easier accessibility. The performance of PET CT varies according to the nature of the tumour, the location of peritoneal carcinomatosis but also the devices used. The correlation between histology and imaging is not perfect: it is an examination to be reserved to supra diaphragmatic extension. The evolution of the techniques will allow us to consider an improvement of the diagnostic performances and an evolution of our surgical care.

Declarations of interest: none

Table 1 -

 1 Characteristics of the population.

	Characteristics of the population.	n = 90
	Age (years) mean ± SD [range]	58.1 ± 11.8 [30-85]
	BMI (kg/m 2 ) mean ± SD [range]	24.4 ± 5.2 [16.4-44]
	Parity mean ± SD [range]	1.6 ± 1 [0-8]
	Nulliparous (%)	23/90 (25.6%)
	Post-Menopausal (%)	62 (68.9%)
	Hormone replacement therapy (%)	20 (32.2%)
	Follow up (month)	64.5 ± 91 (6-264)
	CA 125 at diagnosis	1158 (12-10 400)
	CA 19-9 at diagnosis	157 (0-3093)
	History of
	-appendectomy	21 (23.3%)
	-unilateral adnexectomy	3 (3.3%)
	Diabetes (%)	5/90 (5.5%)
	HBP (%)	16/90 (17.8%)

SD: Standard Deviation; HTM: hormonal treatment of menopause; BMI: body index mass; HBP: High Blood Pressure

Table 2 -

 2 FIGO stage.

	FIGO stage

Table 3 -

 3 Accuracy of peritoneal carcinomatosis diagnosis by FDG PET CT

		Omentum	SI	Colonic	Cupola	Ovary Pelvic nodes LA nodes	Global
	Se	25%	7.3%	26.3%	44.4%	54.05% 30%	30.8%	60%
	Sp	75%	97.4% 92.9%	75%	90.9% 83.3%	92.3%	97.2%
	PPV	66.7%	75%	76.9%	50%	90.9%	50%	80%	96.3%
	NPV	66.7%	50.7%	41.8%	29.4%	45.9%	33.3%	42.8%	34%
	Accuracy	41.7%	50.6%	61.25%	64%	67.8%	62.9%	61.5%	76.25%

Se: Sensibility; Sp: Specificity; PPV: Positive predictive value; NPV: Negative predictive value; LA: lumbar aortic; SI: small intestine 20

Table 4 -

 4 Accuracy of peritoneal carcinomatosis diagnosis by CT

		Omentum	SI	Colic	Cupola	Ovary	Pelvic	LA nodes
							nodes
	Se	60%	9%	21%	45.8%	80%	43%	40%
	Sp	81%	97% 91.2% 93.3%	53%	78.6%	91%
	PPV	85.7%	75%	70%	84.6%	77.8%	50%	80%
	NPV	48.5%	54%	47%	31.7%	43.75%	27%	37.5%
	Accuracy	67.2%	50%	56%	72.2%	71.1%	66.7%	67%

Se: Sensibility; Sp: Specificity; PPV: Positive predictive value; NPV: Negative predictive value; LA: lumbar aortic; SI: small intestine