Caractérisation combinée par TEP au 18F-FDG et par IRM des lésions hépatiques dans l’échinococcose alvéolaire

Abstract

Positron emission tomography (PET) with 18F-fluorodeoxyglucose (18F-FDG) can be used to evaluate parasitic activity in alveolar echinococcosis (AE) as visualization of host–parasite immune reaction around the lesions. We performed a retrospective interpretation of PET and MR (magnetic resonance) images in 24 patients with AE to compare the results of metabolic imaging to Kodama et al. anatomical classification. All patients underwent hepatic MRI and dual-time point FDG-PET (1hour and 3hours after injection), improving sensitivity of standard FDG-PET in AE. The comparison of the images showed perilesional 18F-FDG uptake in all seven patients with type 1 (multiple microcysts without a solid component) and type 2 (multiple microcysts with a solid component) lesions and in ten of 12 patients with type 3 lesions (a solid component surrounding cysts and microcysts). No abnormal perilesional uptake was observed at standard and delayed PET acquisitions in two of 12 patients with type 3 lesions and in all five patients with type 4 (a solid component without microcysts) and type 5 (a large liquid cavity without microcysts) lesions. Our study demonstrates a strong correlation between anatomical “microcystic” aspect and metabolic activity of AE lesions in 89.5% of cases. Thus, microcysts and metabolic perilesional activity seem correlated to parasite activity, which suggests an important role to combined follow-up of AE patients, through multimodality imaging using MRI and 18F-FDG-PET scan.