Intérêt de la TEP/TDM au 18fluorodésoxyglucose dans le bilan initial des lymphomes du système nerveux central des patients immunocompétents

Abstract

IntroductionPrimary central nervous system lymphoma (PCNSL) is a rare malignant lymphoma where disease is limited to the central nervous system. The diagnosis is suspected on brain MRI and confirmed after histological examination, in the absence of systemic involvement. Conventional systemic assessment includes CT, bone marrow biopsy and testicular examination. The primary objective of this study was to evaluate the use of FDG-PET in the initial systemic assessment of suspected PCNSL. Materials and methodsExamination of 21 immunocompetent patients, who have had an FDG-PET for the diagnosis of a cerebral lymphoma before any chemotherapy treatment, was reviewed. All the conventional systemic assessments were negative. ResultsSystemic involvement was detected in three patients (14%). Diagnostic was confirmed histologically in one patient, and based on combined pieces of evidence in two others. The brain lesions’ metabolism was high (mean SUVmax: 15.5±5.4). Thirty-five of the 45 (78%) lesions visible on contrast-enhanced MRI resulted in a pathological cerebral uptake. The infracentimetric enhancements were only visible in 50% of cases (8/16). One-year PFS was weaker in the group of patients with the most FDG avid lesions (SUVmax≥15; P=0.015). This relation was also found and persisted was confirmed in Kaplan-Meier analysis on the whole follow-up by using a ratio of the tumoral uptake by average hepatic uptake with a threshold of 7 (P=0.001). ConclusionsThe results of this work suggest that the FDG-PET could be useful in the systemic initial assessment of PCNSL.