Purpose: In this study, Tc MDM (bis-methionine-DTPA) SPECT was used for the detection and differentiation of recurrent/residual glioma from radiation necrosis and the results were compared with dynamic susceptibility contrast-enhanced (DSCE)-MRI and clinical findings.
Materials and methods: Twenty-eight patients (18 men and 10 women; mean ± SD age, 41.4 ± 15.03 years) with histologically proven glioma (grade IV, 14; grade III, 7; grade II, 7) who were planned for postsurgical standard radio/chemo therapy were recruited prospectively. All the patients underwent technetium Tc MDM SPECT/CT and DSCE-MRI imaging at 6 months after surgery/radio-chemotherapy, 9 of 28 patients also underwent SPECT imaging at 1 to 2 weeks after surgery.
Results: Tc MDM SPECT/CT analysis demonstrated significantly higher target to nontarget (T/NT) ratio of the radiotracer in tumor recurrence than in radiation necrosis (3.59 ± 1.70 vs 1.16 ± 0.42). Likewise, the normalized cerebral blood volume (nCBV) values in patients with tumor recurrence were also significantly higher than in radiation necrosis (5.16 ± 2.30 vs 1.63 ± 0.94). A positive correlation (rho = 0.823, P < 0.0001) between T/NT ratios and nCBV was observed. The cutoff T/NT ratios and nCBV values estimated by receiver operating characteristic analysis were greater than 1.50 (area under the curve, 0.944 ± 0.34) and greater than 2.12 (area under the curve, 0.931 ± 0.39), respectively. Combining the results of Tc MDM SPECT/CT, DSCE-MRI, and clinical findings, diagnosis of recurrent/residual glioma or radiation necrosis was made in 18 and 10 patients, respectively. Sensitivity and specificity of 2 techniques were comparable, that is, 92.0%: 78.6% for MDM SPECT/CT and of 92.0%: 71.4% for DSCE-MRI, respectively.
Conclusion: Thus, combining MDM SPECT with DSCE MRI may provide an accurate method for differentiation of tumor recurrence from radiation-induced necrosis in glioma patients.