CORRELATION BETWEEN GD-ENHANCED MR-IMAGING AND HISTOPATHOLOGY IN TREATED AND UNTREATED 9L RAT-BRAIN TUMORS

Gadolinium-based MR imaging contrast agents cause signal enhancement o f intracerebral tumors on T-1-weighted MR images because they cross th e compromised blood-brain barrier, increasing the T-1 relaxation rate of extracellular water. Tumor extent measured by Gd-enhanced MR imagin g often does not agree with T-2-weighted MRI or biopsy measurements, d ue to possible peritumoral barrier defects or infiltration of tumor ce lls beyond the region of enhancement. In this study, the 9L rat brain tumor model was used to measure the correlation between tumor size mea sured by Gd-enhanced and unenhanced MRI and histological measurements, There was excellent agreement between Gd-enhanced MRI measurements an d histology. Morphological features of untreated 9L intracranial tumor s and those treated with radiation and/or cisplatin were compared with histological features, No significant change in intracranial tumor si ze was detected in the treated animals up to 7 days following treatmen t, despite substantial tumor necrosis evident on histological analysis .