DYNAMIC IMAGING OF INTRACRANIAL LESIONS USING FAST SPIN-ECHO IMAGING - DIFFERENTIATION OF BRAIN-TUMORS AND TREATMENT EFFECTS

The purpose of this study was to develop a technique for differentiati ng between recurrent brain tumors and treatment-related changes, such as radiation necrosis, using dynamic MRI. Ninety-five patients with in tracranial mass lesions were evaluated using T1-weighted fast spin-ech o (FSE) MRI at 1.5 T. Pathologies included treatment-related changes ( n = 32), primary tumors (n = 41), metastatic tumors (n = 5), meningiom as (n = 4), and mixed primary/treatment related changes (n = 13), Sign al enhancement-time curves were analyzed by fitting to a sigmoidal-exp onential function. Maximal enhancement rates were calculated as the fi rst derivative of the fitted curve. Based on the maximal enhancement r ates, treatment-related changes could be differentiated from primary t umors, metastatic tumors, and meningiomas at the P < .05 confidence le vel. Lesions of mixed tumor and treatment-related change had intermedi ate values. Dynamic MRI can be used to differentiate treatment-related changes from primary tumors in previously treated patient populations based on maximal enhancement rates,Individual case studies demonstrat e the clinical significance of these findings.