Evaluation of 99mTc-l-Methionine Brain SPECT for Detection of Recurrent Brain Tumor: a Pilot Study with Radiological and Pathological Correlation

Purpose: To evaluate technetium labeled l-methionine for imaging recurrent brain tumors. Material and Methods: Brain SPECT with 99mTc-l-methionine was performed to evaluate tumor viability in 42 patients with primary brain tumor. Findings of SPECT were correlated with radiological and histopathological findings as reference. Results: 99mTc-l-methionine showed localized increased uptake in 40 patients with tumor recurrence, whereas 2 patients with post-radiation gliosis did not show tracer accumulation. A low differential uptake rate (DUR) 2.43±0.74 and methionine retention (MR) index 0.93±0.03 was seen in cases of post-radiation gliosis. A high DUR (36.20±10.31) and MR index (4.87±2.37) was seen in cases of recurrent tumor. Mean DUR in high-grade tumors (44.01±8.46) was significantly higher (P<0.001) than in low-grade tumors (30.42±7.38), and mean MR index in high-grade tumors (7.03±2.05) was significantly higher than in low-grade tumors (3.27±0.82) (P<0.001). Conclusion: 99mTc-l-methionine can be used as a SPECT tracer to differentiate tumor recurrence from post-radiation gliosis