The diagnostic role of 18F-FDG PET for primary central nervous system lymphoma

Abstract

Objective 18F-FDG PET has become one of the most important methods for studying malignant lymphoma, but its diagnostic role for primary central nervous system lymphoma (PCNSL) has not been established. The aim of this study is to determine the appropriate cut-off values of FDG uptake and to investigate how corticosteroid administration influences PCNSL. MethodsWe retrospectively reviewed 82 patients with contrast-enhanced brain tumors who underwent an FDG PET scan at onset, including 19 PCNSLs. FDG uptake of the lesion was assessed by the maximum standardized uptake value (SUVmax) and the ratio of tumor to normal contralateral cortex activity (T/N ratio). Receiver operating characteristic (ROC) curves were generated from the SUVmax and T/N ratios. To investigate the influence of corticosteroid application before a FDG PET scan, we evaluated the association between the FDG uptake of the lesion and the cumulative dose of corticosteroid administration on 13 PCNSL patients who had received steroid treatment before an FDG PET examination. ResultsThe mean FDG SUVmax and T/N ratio of PCNSLs were 22.6 and 2.79, respectively, and these values were significantly higher than that of the other malignant brain tumors.ROC analysis indicated that the evaluation of FDG uptake using the T/N ratio was more reliable than the SUVmax with respect to the differential diagnosis. When PCNSL patients went without steroid application before FDG PET, the accuracy of the T/N ratio with a cut-off point of 2.0 was 91.1%, the sensitivity was 94.7%, and the specificity was 87.3%. Although there are no significant differences in the FDG T/N ratio for PCNSL patients with or without steroid treatment, a negative correlation was found between the T/N ratio and cumulative dose of corticosteroid before PET study (r = 0.71, p = 0.032). ConclusionsWe concluded that the T/N ratio was superior to SUVmax for FDG uptake assessment as for distinguishing PCNSLs from other malignant brain tumors; the appropriate T/N ratio cut-off point was 2.0. In addition, FDG uptake could be influenced by cumulative doses of corticosteroid before a PET scan, and thus this fact should be taken into consideration when evaluating FDG PET for PCNSL diagnosis.

Diagnostic value of using 18F-FDG PET and PET/CT in immunocompetent patients with primary central nervous system lymphoma: A systematic review and meta-analysis

“…It is well known that FDG-uptake on diffuse large B-cell lymphoma is higher than that on other types of lymphoma, and this characteristic feature could be helpful in differentiating between B-cell lymphoma and other histological tumors [26]. Similarly, PET can identify degenerative diseases, multiple sclerosis, infectious diseases and cerebral infarction [27].…”

A new diagnostic marker for differentiating multicentric gliomas from multiple intracranial diffuse large B-cell lymphomas on 18F-FDG PET images

“…The mean T/N ratio of 18 F-FDG for distinguishing PCNSLs ranges from 2.36 to 2.79. [ 7 , 16 , 25 ] In 11 C-MET PET, the rate of 11 C-MET uptake—defined as ΔSUV max (the ratio of SUV max in the late and early phases of PET)—could enable clinicians to distinguish glioblastomas and DLBCLs. [ 5 ]…”

“…Regional uptakes of 18 F-FDG and 11 C-MET were expressed as SUV, calculated according to the following equation: [tissue activity (Bq/mL) × (body weight, g)]/[injected radioisotope activity (Bq)]. [ 7 ] The SUV max of a tumor was sampled from a single pixel exhibiting the highest 18 F-FDG or 11 C-MET accumulation. The T/N ratio of 18 F-FDG PET images was defined as the ratio of SUV max of the lesion to the contralateral normal white matter.…”

“…Previous studies have demonstrated that maximum standardized uptake value (SUV max ) and tumor-to-normal tissue (T/N) ratio on 18 F-FDG PET images are appropriate for distinguishing DLBCLs from glioblastomas and other malignant brain tumors. [ 5 , 7 ] In addition, ΔSUV max on 11 C-MET PET images could be potentially useful for differential diagnosis of intracranial DLBCL and glioblastoma. [ 5 ]…”

“…18 F-FDG and 11 C-MET are commonly used radiotracers that could help acquire additional information and improve the diagnostic accuracy of PET for distinguishing between these 2 tumors. [ 9 ] Although some previously reported indicators, such as SUV max and T/N ratio, have been shown to be effective in differentiating solitary gliomas and lymphomas, [ 5 , 7 , 10 ] the diagnostic value of 18 F-FDG PET for distinguishing multicentric gliomas from multiple DLBCLs has not been well evaluated.…”