N Molinari

A Bourdon

M Benkiran

Delphine De Verbizier

V Boudousq

Denis Mariano-Goulart

Fidani Thibault
email: thibault.fidani@gmail.com

Vauchot Fabien

Molinari Nicolas

Bourdon Aure Ĺie

Benkiran Meriem

Boudousq Vincent

Mariano-Goulart Denis

Thibaut Fidani

Should patients with an incidental finding of focal myocardial 18FDG uptake be screened by myocardial perfusion scintigraphy?

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

fluoro-deoxy-glucose positron-emission-tomography-computed-tomography. Methods: In our retrospective multicentric study, patients were included if they had had an incidental finding of myocardial focal F-18-fluoro-deoxy-glucose uptake on a routine F-18-fluoro-deoxyglucose positron-emission-tomography-computed-tomography and had also undergone myocardial perfusion scintigraphy within 3 months before or after the F-18-fluoro-deoxyglucose positron-emission-tomography-computed-tomography. Patients with a pattern of ischemia or scar on the myocardial perfusion scintigraphy in the same territory as the focal F-18-fluoro-deoxy-glucose uptake were considered positive. Results: Seven of the 34 included patients were positive, with an abnormality on the MPS data in the same territory as the focal myocardial F-18-fluoro-deoxy-glucose uptake. 2 of the 6 patients with focal F-18-fluorodeoxy-glucose uptake in the left anterior descending vascular supply territory and 2 of the 4 patients with focal F-18-fluoro-deoxy-glucose uptake in the standard right coronary artery territory had an abnormal myocardial perfusion scintigraphy. All 12 patients with focal F-18fluoro-deoxy-glucose uptake restricted to the basal anterolateral and basal inferolateral segments were negative. Conclusion: Patients with an incidental finding of focal F-18-fluorodeoxy-glucose uptake on a routine F-18-fluoro-deoxy-glucose positron-emission-tomographycomputed-tomography may be considered as being at risk for coronary artery disease, when this uptake is multisegmentary in the same typical coronary territory and not restricted to the basal anterolateral and basal inferolateral segments. myocardial 18 FDG uptake Résumé But : Une hyperfixation focale du 18 FDG sur le myocarde peut être un signe d'ischémie myocardique de repos. Le but de notre étude était d'évaluer la pertinence de proposer un complément d'exploration par scintigraphie de perfusion myocardique chez les patients ayant une découverte fortuite d'une hyperfixation myocardique focale de 18 FDG sur un TEP/TDM 18

TEP/TDM au 18 FDG, scintigraphie myocardique de perfusion, cardiopathie ischémique, hyperfixation myocardique focale

Introduction

The human heart uses different energy metabolic pathways to assure its pump function. The major fuels for respiration in the myocardium are carbohydrates and free fatty acids. The preferential energy metabolic pathway switches throughout the day and is determined by a number of parameters, including fasting times and plasma substrate levels [START_REF] Taegtmeyer | Assessing Cardiac Metabolism: A Scientific Statement From the American Heart Association[END_REF]. Yet even under strict conditions, the myocardium metabolism remains unpredictable [START_REF] Inglese | Spatial and temporal heterogeneity of regional myocardial uptake in patients without heart disease under fasting conditions on repeated whole-body 18F-FDG PET/CT[END_REF]. Glucose is the primary substrate under ischemic conditions because of the anaerobic condition, which stimulates the glucose metabolism [START_REF] Rosano | Cardiac metabolism in myocardial ischemia[END_REF][START_REF] Camici | Myocardial metabolism in ischemic heart disease: basic principles and application to imaging by positron emission tomography[END_REF].

The pattern of myocardium uptake of F-18-fluoro-deoxy-glucose ( 18 FDG) can be separated in three groups: no significant uptake, diffuse uptake, and focal or regional uptake [START_REF] Maurer | How to differentiate benign versus malignant cardiac and paracardiac 18F FDG uptake at oncologic PET/CT[END_REF].

An incidental finding of focal myocardial 18 FDG uptake is sometimes detected on the 18 FDG positron-emission-tomography-computed-tomography (PET/CT) performed as part of the routine clinical evaluation of solid cancers, hematologic malignancies, inflammatory diseases and infections. Its interpretation is challenging because of the intrinsic inter-and intraindividual variation in myocardial metabolism [START_REF] Gropler | Nonuniformity in myocardial accumulation of fluorine-18-fluorodeoxyglucose in normal fasted humans[END_REF].

Focal 18 FDG uptake in the myocardium can be a sign of myocardial ischemia [START_REF] Dou | Use of resting myocardial 18F-FDG imaging in the detection of unstable angina[END_REF], which can include silent ischemia at rest, silent ischemia at stress and hibernating myocardium after a myocardial infarction [START_REF] Nagy | Silent myocardial ischemia during PET[END_REF]. This specificity is used in clinical routine to assess myocardial viability in patients who are potential candidates for revascularization procedures after a myocardial infarction, and 18 FDG PET/CT is now the method of reference for this assessment [START_REF] Molchanova-Cook | Role of FDG-PET in Evaluation of Myocardial Viability[END_REF][START_REF] Slart | Nuclear cardiac imaging for the assessment of myocardial viability[END_REF]. Myocardial viability in 18 FDG PET/CT can be assessed following a strict protocol of glucose-insulin loading to force the myocardium metabolism toward glucose utilization [START_REF] Sarikaya | Status of F-18 fluorodeoxyglucose uptake in normal and hibernating myocardium after glucose and insulin loading[END_REF].

But focal 18 FDG uptake can also be physiological [START_REF] Fukuchi | Benign variations and incidental abnormalities of myocardial FDG uptake in the fasting state as encountered during routine oncology positron emission tomography studies[END_REF] or part of a noncoronary pathology, like cardiac sarcoidosis [START_REF] Ayoub | Advanced imaging of cardiac sarcoidosis[END_REF][START_REF] Erthal | Imaging of cardiac sarcoidosis[END_REF]. Because of its noninvasiveness, high diagnostic performance and wide availability, myocardial perfusion scintigraphy (MPS) using single photon emission computed tomography (SPECT) is a standard method for coronary artery disease (CAD) screening, characterization and follow-up, particularly for silent myocardial ischemia [START_REF] Mowatt | Systematic review of the effectiveness and cost-effectiveness, and economic evaluation, of myocardial perfusion scintigraphy for the diagnosis and management of angina and myocardial infarction[END_REF][START_REF] Lee | Prognostic Value of FDG Uptake of Portal Vein Tumor Thrombosis in Patients With Locally Advanced Hepatocellular Carcinoma[END_REF].

A pattern of scar on the MPS may hide hibernating myocardium. If such pattern is located in the same territory of a 18 FDG uptake on a PET/CT, it suggests the presence of myocardial viability. Indeed myocardial hypoperfusion on MPS covers a range of different intensities of myocardial ischemia from stress myocardial ischemia to hibernating myocardium and may underestimate viability especially with sestamibi [START_REF] Marcassa | Restredistribution thallium-201 and rest technetium-99m-sestamibi SPECT in patients with stable coronary artery disease and ventricular dysfunction[END_REF].

The goal of this retrospective study was to assess whether MPS should be used to look for potential CAD in patients who present with an incidental discovery of focal 18 FDG uptake in the myocardium on routine clinical 18 FDG PET/CT. In most cases, patients who require medical imaging by 18 FDG PET/CT have diseases with a poor prognosis, are under heavy treatment, are older than the average population and may have several comorbidities. These patients are more likely to develop the cardiovascular complications of chronic disease, treatment side effects, and the risk factors associated with cancer [START_REF] Rominger | 18F-FDG PET/CT identifies patients at risk for future vascular events in an otherwise asymptomatic cohort with neoplastic disease[END_REF].

Methods

Patients

This retrospective observation study was approved by our institutional review board (number 2019_IRB-MTP_02-03).

All patients were retrospectively recruited from the nuclear medicine departments of Montpellier University Hospital, France, and Nimes University Hospital, France, between January 2015 and May 2019. During this period, patients with an incidental finding of focal myocardial 18 FDG uptake on a routine 18 FDG PET/CT and who had undergone MPS within 3 months before or after the 18 FDG PET/CT were included. The cases showing focal myocardial 18 FDG uptake were identified by retrospective review. Patients who had had the 18 FDG PET/CT specifically to assess cardiac disease were not included.

18 FDG PET/CT protocols

Montpellier University Hospital and in Nimes University Hospital, 18 FDG PET/CT acquisitions were performed 60 minutes following an IV injection of 3.5 MBq/kg of 18 FDG after a fasting period of at least 4 hours. The PET axial field of view encompassed brain, neck, thorax, abdomen, and pelvis. In Montpellier, PET/CT acquisitions were performed using a Siemens Biograph mCT 20 Flow scanner with time-of-flight mode. Images were reconstructed using the manufacturer's dedicated software and specifications (3D OSEM using 21 subsets and 2 iterations including PSF correction followed by post-filtering with a 3mm wide Gaussian kernel). Image matrices were sampled on a 400x400 grid with a voxel size of 2x2x2 mm 3 . In Nimes, PET/CT examination was performed using a General Electric Healthcare Discovery 710 Elite with time-of-flight mode. Images were reconstructed using the manufacturer's dedicated software and specifications (VUE Point FX -SHARP IR -QCLEAR 400 and no filter). Image matrices were sampled on a 256x256 grid with a voxel size of 4x4x4 mm 3 . The attenuation correction for PET was based on the CT data. PET/CT data were analyzed by a nuclear medicine specialist using the Syngo.via viewer (Siemens) in Montpellier and using the Advantage Workstation (General Electric Healthcare) in Nîmes.

Focal myocardial 18 FDG uptake was interpreted from the axial, sagittal, coronal projections and the maximum intensity projection (MIP) on the PET images.

The description of left ventricular myocardial metabolism was based on the nomenclature and standardized segmentation published by the American Heart Association [START_REF] Cerqueira | Standardized myocardial segmentation and nomenclature for tomographic imaging of the heart. A statement for healthcare professionals from the Cardiac Imaging Committee of the Council on Clinical Cardiology of the American Heart Association[END_REF] ). In this study, focal 18 FDG uptake was defined as an unique segmentary or multisegmentary myocardial uptake in one of the three main vascular supply territories.

Patients with circumferential basal uptake, focal uptake restricted to the papillary muscles or with more than one myocardial focal 18 FDG uptake were not included.

Myocardial perfusion scintigraphy: Protocols

At Montpellier University Hospital, patients were imaged using a solid-state dedicated cardiac camera (Discovery NM530c; General Electric Healthcare). They refrained from caffeine and methylxanthine-containing substances for at least 12 hours before their scans. Patients underwent a 1-day rest/stress protocol. The imaging was performed after IV injection of 3.7

MBq/kg of 99m Tc-tetrofosmine at rest and 11 Mbq/kg 99m Tc-tetrofosmine at peak stress. The stress tests were performed on a treadmill with a 12-lead ECG monitored by a cardiologist.

The stress acquisitions were completed by IV injection of dipyridamole in patients without medical contraindication.

At Nimes University Hospital, patients were imaged using a conventional two-headed hybrid gamma camera (SPECT/CT NMCT 670; General Electric Healthcare). They refrained from caffeine and methylxanthine-containing substances for at least 12 hours before their scans.

Patients underwent a 1-day stress protocol if no abnormality was identified and a 1-day rest/stress protocol if an abnormality was detected on the stress screening. The imaging was performed after injection of 3.7 MBq/kg of 99m Tc-sestamibi at peak stress and 11 MBq/kg 99m Tc-sestamibi at rest. The stress tests were performed on a treadmill and monitored with a 12-lead ECG by a cardiologist. The stress acquisitions were completed by IV injection of dipyridamole in patients without medical contraindication.

SPECT data were analyzed by a nuclear medicine specialist using Xeleris software (General Electric Healthcare) in both Montpellier and Nimes. On the SPECT data, ischemia was defined as a reversible stress perfusion defect and scar as a significant fixed defect with corresponding abnormal wall thickening. Fixed defects with normal wall thickening at rest in the same segment were regarded as artifacts. A scar pattern on the MPS in the same territory as 18 FDG uptake on the 18 FDG PET/CT suggested myocardial viability.

Patients with a pathological finding (ischemia or scar) on the SPECT data in the same territory as the 18 FDG uptake on the PET/CT were considered positive.

Statistical analysis

Categorical variables are characterized in terms of number (percentage) and continuous variables are presented as mean value ± standard deviation.

Results

Of 235 patients who had undergone MPS within 3 months before or after a 18 FDG PET/CT, 34 patients with a discovery of a focal myocardial 18 7 of the 34 patients had abnormal SPECT data in the same territory as the myocardial 18 FDG uptake and were considered positive. 4 of the 7 positive patients had pattern of ischemia on the SPECT data and 3 of the 7 positives had pattern of scar on the SPECT data. The myocardial 18 FDG uptake was multisegmentary in the same coronary territory in all 7 positive patients. All patients with a 18 FDG hot spot restricted to one segment had negative SPECT myocardial perfusion scintigraphy.

Figure 1 summarizes the localization of the myocardial 18 FDG uptake in the overall population and the repartition of patients with a positive MPS. 18 FDG focal uptake was more frequent in the LCx territory (71%).

In the LCx territory, 3 of 24 patients had a positive MPS scintigraphy (1 pattern of ischemia and 2 patterns of scar). 12 of these 24 patients had a focal myocardial 18 FDG uptake restricted to the basal anterolateral and basal inferolateral segments (segments 5 and 6). 0 of these 12 patients had a positive MPS scintigraphy. This pattern is described in Figure 2.

3 of the 12 patients with a focal myocardial 18 FDG uptake in the LCx territory wider than segments 5 and 6 were positive on MPS scintigraphy. Figure 3 shows a patient with a pattern of scar in the LCx territory. 2 of these 3 patients underwent a coronary angiography consecutive to the MPS: one was a >70% stenosis of a left marginal artery and one was a chronic occlusion of LCx. The third patient had a complementary stress echocardiography, which corroborated the findings of the SPECT data (lateral myocardial infarction), but no coronary angiography was required, according to the cardiologist.

In the LAD territory, 2 of 6 patients were positive on MPS scintigraphy (2 pattern of ischemia). Figure 4 shows a patient with a pattern of ischemia in the LAD territory. These 2 patients underwent coronary angiography following the MPS: one was a chronic occlusion of LAD and one showed an absence of significant restenosis in a previously placed LAD stent.

In the RCA territory, 2 of 4 patients were positive on MPS scintigraphy (1 pattern of ischemia and 1 pattern of scar). Figure 5 shows a patient with a pattern of scar in the RCA territory.

One of these patient underwent coronary angiography following the MPS which concluded in a chronic occlusion of RCA2. For the second patient with a finding of a 10% inferior wall scar on the MPS data, the cardiologist required only follow-up.

Discussion

Soon after the first PET scanners were introduced into practical routine, 18 FDG PET/CT became the preferred technique for imaging heart glucidic metabolism. In daily clinical routine, nuclear medicine specialists regularly observe focal 18 FDG uptake in a myocardium wall. The nonuniformity of myocardial accumulation of 18 FDG is well known and focal disparities have been described, with the septum and anterior walls showing less activity than the inferior and lateral walls [START_REF] Gropler | Nonuniformity in myocardial accumulation of fluorine-18-fluorodeoxyglucose in normal fasted humans[END_REF]. Indeed, the shift in energy metabolism from glucose oxidation to fatty acid oxidation is spatially and temporally heterogeneous [START_REF] Inglese | Spatial and temporal heterogeneity of regional myocardial uptake in patients without heart disease under fasting conditions on repeated whole-body 18F-FDG PET/CT[END_REF]. Myocardial glucose utilization depends on several parameters, notably the fasting length. However, it is increased on 18 FDG PET/CT in a context of resting ischemia, even without clinical or ECG signs in patients with unstable angina [START_REF] Camici | Myocardial metabolism in ischemic heart disease: basic principles and application to imaging by positron emission tomography[END_REF]. Myocardial glucose utilization is also increased in viable myocardium after myocardial infarction and 18 FDG PET is currently the method of reference to assess the viability [START_REF] Molchanova-Cook | Role of FDG-PET in Evaluation of Myocardial Viability[END_REF][START_REF] Jamiel | The role of myocardial viability in contemporary cardiac practice[END_REF]. Since glucose metabolism in the fasting state is heterogeneous and unpredictable even in the normal myocardium, it is challenging to diagnose the presence of CAD by fasting 18 FDG PET imaging alone, at rest. Indeed, focal 18 FDG uptake may have many other pathological etiologies such as cardiac sarcoidosis [START_REF] Erthal | Imaging of cardiac sarcoidosis[END_REF][START_REF] Ayoub | Advanced imaging of cardiac sarcoidosis[END_REF] and primitive or secondary tumors [START_REF] Saponara | 18F-FDG-PET/CT imaging in cardiac tumors: illustrative clinical cases and review of the literature[END_REF][START_REF] Rahbar | Differentiation of malignant and benign cardiac tumors using 18F-FDG PET/CT[END_REF]. Several patterns of focal 18 FDG uptake have been described, such as increased uptake in the right atrium in atrial fibrillation [START_REF] Fujii | Increased FDG uptake in the wall of the right atrium in people who participated in a cancer screening program with whole-body PET[END_REF] and a defect of 18 FDG fixation in the septal wall in patients with complete left branch block [START_REF] Zanco | Effects of left bundle branch block on myocardial FDG PET in patients without significant coronary artery stenoses[END_REF].

Correlation between an incidental finding of focal 18 FDG uptake in the apex and anterior wall and CAD had been described by Minamito et al. [START_REF] Minamimoto | Incidental focal FDG uptake in heart is a lighthouse for considering cardiac screening[END_REF] in a retrospective study of 20 patients who had undergone ECG, US, MPS, CT coronary angiography and invasive x-ray coronary angiography. Garcia et al. showed a further correlation between myocardial vessel calcifications and the frequency of focal 18 FDG myocardial uptake [START_REF] Garcia | Incidence of focal myocardial (18)F-FDG uptake and correlation with coronary calcifications by PET/CT[END_REF]. Finding of unknown ischemia on an MPS performed after finding a focal 18 FDG uptake has been described in a case report [START_REF] Ilonca | Diagnosis of silent myocardial ischemia during the staging of HIV-associated lymphoma with FDG PET/CT[END_REF].

Our study confirms that myocardial 18 FDG uptake restricted to the basal lateral segments (segments 5 and 6) should not be considered a pattern for CAD and that no further investigations are needed in this case. Such findings have been described and the studies concluded that the basal lateral (segments 5 and 6) pattern should be considered physiological [START_REF] Maurer | Variable cardiac 18FDG patterns seen in oncologic positron emission tomography computed tomography: importance for differentiating normal physiology from cardiac and paracardiac disease[END_REF][START_REF] Maurer | How to differentiate benign versus malignant cardiac and paracardiac 18F FDG uptake at oncologic PET/CT[END_REF]. Indeed none of the 12 patients with this pattern had a positive MPS in our study. This typical pattern is shown in Figure 3.

Myocardial 18 FDG uptake was more frequent in the LCx territory than in the LAD and RCA territories. These findings confirm an earlier report that the lateral wall is probably the last part of the myocardium to shift from glycolysis to beta oxidation in its energy metabolism.

Indeed, Gloper et al. showed that there is overall more 18 FDG activity in the lateral wall than in the rest of the myocardium [START_REF] Gropler | Nonuniformity in myocardial accumulation of fluorine-18-fluorodeoxyglucose in normal fasted humans[END_REF].

In our study, 7 of the 34 patients had abnormal SPECT data (ischemia or scar based on the MPS) in the same standard vascular supply territory as the finding for the myocardial 18 FDG uptake. Despite the low numbers of patients included, our results suggest that it might be relevant to propose a screen test for myocardial ischemia in patients with an incidental finding of a focal myocardial 18 FDG uptake. Indeed in our study, the third of patients (2 on 6 patients)

with 18 FDG hotspot in the LAD territory were positive, the half of patients (2 on 4 patients)

with 18 FDG hotspot in the RCA territory were positive and the quarter of patients (3 on 12 patients) with 18 FDG hot spot in the LCx territory wider than the segments 5-6 were positive.

But a study with a much wider population is required to confirm these results. No further investigations were done in patients with 18 FDG hot spot and normal MPS.

3 of the 7 positive patients had an MPS with a pattern of scar. The high 18 FDG uptake in these patients suggested a viable myocardium. Indeed, myocardial viability can be determined by the mismatch between the high 18 FDG metabolism in the same territory as the hypoperfusion on the SPECT rest and stress acquisitions.

However, focal 18 FDG uptake remained nonspecific in the majority of the patients in our study and should not be considered pathological without further investigations, especially if located in the LCx vascular supply.

Prevalence of focal myocardial 18 FDG uptake in the 235 patients who had had a PET/CT and a MPS less than 3 months apart was 14%. The prevalence of focal myocardial 18 FDG uptake might be overestimate in this study, as compared to the standard population who underwent 18 FDG PET/CT, because the majority of the MPS were done following the finding of the focal myocardial 18 FDG uptake.

In 6 of the 7 positive patients, the MPS was performed after the findings on the PET/CT and no anteriority of CAD before the incidental finding of the 18 FDG uptake had been found for 5 of the 7 positive patients, indicating the importance of documenting this finding in the medical report. One of the two patients with anteriority of CAD had a stent in the LAD following an acute coronary syndrome and the other was only medically treated for stable angina.

Patients who require 18 FDG PET examinations often have a disease with poor prognosis (malignant tumors), may have several comorbidities [START_REF] Sarfati | Identifying important comorbidity among cancer populations using administrative data: Prevalence and impact on survival[END_REF], are generally older than the average population and may be under heavy medication (possibly cardiotoxic and/or immunosuppressive therapy), all of which may lead to cardiac disease. These patients are more likely to develop the complications of a chronic inflammatory state, treatment side effects and chronic infection. Moreover, cancer can be considered a standalone cardiovascular risk factor [START_REF] Giza | Cancer as a Risk Factor for Cardiovascular Disease[END_REF]. Patients with oncologic diseases who need PET/CT investigation may be considered a group at risk of CAD, similar to populations of diabetic patients and HIVinfected patients [START_REF] Jacquet | Should HIV-infected patients be screened for silent myocardial ischaemia using gated myocardial perfusion SPECT?[END_REF].

The main limitation of our study was the low number of patients included in the analysis. An other limitation of the study was that 2 of the 7 positive patients did not undergo invasive coronarography angiography following the discovery of the perfusion abnormality on the MPS. But the 2 patients had a cardiac follow up following the results of the MPS.

The retrospective nature of this study is also a major limitation for extrapolating our findings.

This study was designed to evaluate the relevance of myocardial perfusion scintigraphy for patients with focal myocardial uptake on a 18 FDG PET/CT, without considering account the cardiac histories of the patients. Some of the MPS were performed following the discovery of the myocardial focal uptake on the PET/CT, whereas other MPS were completely unrelated to the PET/CT and were performed in patients with known CAD or in patients with cardiovascular risk factors, in line with the guidelines and indications for MPS. A prospective study may be useful to prevent this potential bias.

Conclusion

Our study confirms that the diagnosis of coronary artery disease might be suspected in patients with an incidental finding of myocardial focal 18 FDG uptake, only when this finding is multisegmentary in the same typical coronary vascular territory and not restricted in the basal anterolateral and basal inferolateral segments. Indeed, our study suggests that these patients may be considered as being at risk for CAD and that a screening test to detect CAD might be justified. Focal 18 FDG uptake in the basal anterolateral and basal inferolateral segments should no lead to further investigation. However, prospective studies and studies with wider population are needed to assess the relevance of our findings regarding CAD screening.

Figure 1

Localization of the focal myocardial 18 FDG uptake in the overall population and by coronary vascular supply territory. *basal anterolateral and basal inferolateral segments Localisation de l'hyperfixation myocardique focale de 18FDG dans la population par territoire coronaire. *segments anterolatero basal et inferolatero basal

Example of patients with focal myocardial 18 FDG uptake restricted to the basal anterolateral and basal inferolateral segments (segments 5 and 6).

Exemple de patients avec une hyperfixation myocardique focale restreinte aux segments anterolatero basal et inferolatero basal (segments 5 et 6)

Example of a 74-year-old female patient with a multisegmentary 18 FDG uptake in LCx territory.

SPECT perfusion imaging showed pattern of scar in the lateral wall. The discordance between the high 18 FDG uptake and the hypoperfusion suggests myocardial viability in the lateral wall.

The coronary angiography, consecutive to the MPS, showed a chronic occlusion of the LCx. Example of an 86-year-old patient with focal myocardial 18 FDG uptake in the LAD territory.

The myocardial perfusion scintigraphy showed a partially reversible ischemia in the LAD territory. The coronary angiography showed an absence of significant restenosis in a previously placed LAD stent.

Exemple d'un patient de 86 ans avec une hyperfixation focale de 18FDG dans le territoire de l'interventriculaire antérieure. La scintigraphie myocardique de perfusion montrait une ischémie partiellement réversible dans le territoire de l'interventriculaire antérieure. La coronarographie, réalisée suite à la scintigraphie myocardique, n'a pas montré de resténose significative du stent de l'IVA qui avait été mis en place de manière antérieure.

Figure 5

Example of a 67-year-old male patient who underwent 18 FDG PET/CT for the evaluation of a pulmonary adenocarcinoma. 18 FDG PET/CT showed 18 FDG uptake in the myocardial inferior wall. SPECT perfusion imaging showed hypofixation in the inferior wall both at rest and stress (wider at stress), suggesting myocardial infarction with perilesional ischemia. The discordance between the high 18 FDG uptake and the hypoperfusion suggests myocardial viability in the inferior wall. The coronary angiography, consecutive to the MPS, showed a chronic occlusion of the RCA.

  FDG de routine. Matériels et Méthodes : Dans notre étude rétrospective et multicentrique, nous avons inclus les patients qui ont eu une découverte fortuite d'une hyperfixation myocardique focale sur un TEP/TDM 18 FDG de routine et qui ont également bénéficié d'une scintigraphie myocardique de perfusion dans les 3 mois avant ou après le TEP/TDM 18 FDG. Les patients avec un diagnostic d'ischémie myocardique ou de séquelle d'infarctus du myocarde sur la scintigraphie myocardique de perfusion dans le même territoire que l'hyperfixation de 18 FDG ont été considérés comme positifs. Résultats : 7 des 34 patients inclus ont été considérés comme positifs. 2 sur 6 patients avec une hyperfixation focale dans le territoire de l'artère interventriculaire antérieure et 2 sur 4 des patients avec une hyperfixation focale dans le territoire de l'artère coronaire droite avaient une scintigraphie de perfusion myocardique anormale dans le même territoire que l'hypermétabolisme glucidique. Sur les 12 patients avec une hyperfixation limitée aux territoires latérobasaux, aucun n'était positif. Conclusion : Les patients avec une découverte fortuite d'une hyperfixation myocardique focale du 18 FDG pourraient être considérés comme un groupe à risque de pathologie coronarienne si cette hyperfixation n'est pas restreinte aux segments anterolatero basal et inferolatero basal.

  Exemple d'une patiente de 74 ans avec une hyperfixation myocardique de 18FDG touchant plusieurs segments dans le territoire de l'artère circonflexe. La scintigraphie myocardique de perfusion retrouvait un pattern de séquelle dans la paroi latérale. La discordance entre l'hypoperfusion et l'hypermétabolisme glucidique indiquait la présence de viabilité myocardique. La coronarographie, réalisée dans les suites, a retrouvé une occlusion chronique de l'artère circonflexe.

Figure 4

 4 Figure 4

  Exemple d'un patient de 67 qui avait bénéficié d'un TEP/TDM 18FDG pour l'évaluation d'unadénocarcinome pulmonaire. Le TEP/TDM 18FDG montrait une hyperfixation focale au niveau de la paroi inférieure. La scintigraphie myocardique de perfusion montrait une séquelle avec ischémie péri-lésionelle. La discordance entre l'hypoperfusion et l'hypermétabolisme glucidique indiquait la présence de viabilité myocardique. La coronarographie, réalisée suite à la scintigraphie myocardique, a retrouvé une occlusion chronique de l'artère coronaire droite.

Table 1 .

 1 FDG uptake (24 males, 10 females; 63.3±12.1 years) were included in the study. The demographic, anthropometric characteristics, clinical indications of 18FDG PET/CT and the distribution of the main cardiovascular risk factors in this population are listed in Nine patients from Nimes University Hospital and 25 patients from Montpellier University Hospital.

Table I

 I Demographic, anthropometric characteristics, clinical indications of18 FDG PET/CT and distribution of the main cardiovascular risk factors in the population.Données démographiques et anthropométriques, indications des TEP/TDM au18 FDG et distribution des principaux facteurs de risques cardio-vasculaires dans la population.

	Characteristics and cardiovascular risk factors		Value
	Age (years, mean ± SD)				63 ± 12
	Male, n (%)					24 (71)
	Female, n (%)				10 (29)
	Body mass index (kg/cm 2 , mean ± SD)			27 ± 5
	Clinical indication of 18 FDG PET/CT
	-Oncologic diseases				29
	-Non oncologic diseases (inflammatory diseases,	5
	infectious diseases)
	Men older than 45 years, n (%)			21 (62)
	Women older than 55 years, n (%)			9 (26)
	Active smoking or cessation <1 year ago, n (%)		15 (44)
	Arterial	hypertension	(≥140/90	mmHg	or	16 (47)
	antihypertensive medication), n (%)
	Dyslipidemia (LDL ≥130 mg/dL or			10 (29)
	HDL <40 mg/dL or medication)
	Body mass index ≥30 (kg/cm2), n (%)			9 (26)
	Type 1 or type 2 diabetes, n (%)			7 (21)
	Personal history of cardiovascular disease (stroke,	12 (35)
	arteriopathy of the lower limbs, coronaropathy) n (%)
	Number of cardiovascular risk factors, n (%)
	Zero					1 (3)
	One					7 (21)
	Two					6 (18)
	Three					8 (23)
	Four					8 (23)
	Five					2 (6)
	Six					2 (6)

Conflict of interests: None