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 Tc-99m-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: Tc-99m-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: Tc-99m-L-methionine can be used as a SPECT tracer to differentiate tumor recurrence from post-radiation gliosis.