Comparison of brain SPECT with 99mTc-MIBI and CT-scan in discriminating of radiation necrosis and brain tumor recurrence [Persian]

Introduction: 99mTc-MIBI has been proposed for use as an imaging agent for various tumors, including breast cancer, lung cancer, lymphomas, melanomas and brain neoplastic lesions. Brain tumors are very common and radiotherapy being major part of treatment following surgery. After radiotherapy, deteriorating clinical status can be due to either radiation necrosis or recurrent tumor. Computed tomography and magnetic resonance imaging offer imperfect discrimination of radiation necrosis and tumor recurrence. Methods: In this study, 26 patients with primary brain tumors and deterioration of clinical status after radiotherapy were evaluated. 99mTc-MIBI brain SPECT was performed 10 minutes and 3 hours after IV injection of 20 mCi 99mTc-MIBI. The images were obtained with ADAC dual head camera. Transverse, coronal and sagital views were reconstructed. Results: Focal 99mTc-MIBI uptake was observed in 14 patients. Eight of these patients expired within 6 months. The CT scan was positive in 7 patients and the rest had equivocal or negative results. Of 12 patients with negative 99mTc-MIBI scan, only 2 patients died during the 6 months follow up. Six of these patients had positive, five had equivocal and one had negative CT scan. Conclusion: Patients with negative MIBI scan, radiation revealed higher survival rate. Focal uptake on 99mTc-MIBI scan is probably due to recurrent tumor, with lower 6 months survival rate. It can be concluded that brain SPECT scan with 99mTc-MIBI is a useful method for discriminating radiation necrosis from tumor recurrence in patients following brain radiotherapy.