Evaluation of FDG PET combined with cardiac MRI for the diagnosis and therapeutic monitoring of cardiac sarcoidosis.

AIM: To compare combined 2-[18F]-fluoro-2-deoxy-d-glucose (FDG)-positron-emission tomography (PET) and cardiac magnetic resonance imaging (CMR) for the diagnosis and therapy monitoring of cardiac sarcoidosis (CS). MATERIALS AND METHODS: Eighty patients with sarcoidosis and a suspicion of CS who underwent PET and CMR were included retrospectively. PET was undertaken after a low-carbohydrate-high-fat diet in all patients using a combined 16-section PET/computed tomography (CT) camera. PET was considered positive (PET+) in cases of focal or multifocal FDG uptake. CMR was considered positive (CMR+) in cases of subepicardial late gadolinium enhancement (LGE). A subgroup of 50 patients (50/80) was monitored during therapy and classified as responders or non-responders. RESULTS: Eighty-two percent of patients with PET+ (9/11) also had CMR+ imaging, with good spatial agreement (kappa=0,79; 95% confidence interval [CI]: 0.65-0.94). Twenty-seven percent (22/80) had residual physiological FDG uptake, with a standardised uptake value (SUV) not significantly different compared to the SUV from pathological uptake (6.4 versus 6 respectively, p=0,92). The clinical response was more frequent in patients with baseline PET+ compared to baseline PET- (80% versus 45%, p=0.07). PET findings improved in all cases under treatment (7/7), whereas LGE improved in only 33% of patients (3/9). CONCLUSION: Due to high risk of false-positive or undetermined findings, PET might be performed as a second-line study in cases of LGE, to assess inflammatory load. In addition, PET seems suitable to predict and assess response under therapy.

[Usefulness of imaging in large vessel vasculitis]. / Place de l'imagerie dans l'évaluation des vascularites de gros vaisseaux.

The imaging is essential for the diagnosis of large vessels arteritis, in order to assess the persistent inflammation of arterial lesions, to evaluate the treatment response and search the vascular complications. In patients with giant cell arteritis (GCA), the aortitis could be suspected in 2 situations: in the presence of general constitutional symptoms or systematic screening of aortitis in patient with confirmed GCA. The frequency of aortitis varies according to the imaging method and could be detected in 40 % of patients with computed tomography and MRI, and approximately in 60 % with FDG-PET/CT. The clinical and prognostic value of systematic detection of aortitis during the GCA remains to be determined. In Takayasu arteritis, imaging is performed to diagnose the large vessels vasculitis, to determine the arterial lesions extension to assess the persistent inflammation of arterial lesions. The persistent vascular inflammation should be suspected in the presence of arterial thickness, of arterial enhancement, a parietal edema and increased arterial FDG uptake (>liver). However, the value of these parameters and the threshold remain to be determined. Thus, the value of FDG-PET/CT and MRI and of parameters used to characterize the persistent arterial inflammation should be further studied.