Contrast-enhanced perfusion MR imaging to differentiate between recurrent/residual brain neoplasms and radiation necrosis

Purpose: To determine the value of dynamic susceptibility contrast enhanced (DSC) MRI (magnetic resonance imaging) perfusion in the characterization of newly developed/enlarging lesions within irradiated regions after treatment of brain tumors. Methods: This prospective cross-sectional study covered 23 patients, 12 females and 11 males. All cases initially presented with histologically proven malignant brain tumors and underwent surgical intervention followed by radiotherapy (+/- chemotherapy). On follow up imaging, they presented with newly developed/progressively enhancing mass lesions at the sites of the primary tumors. All patients then underwent conventional MRI, DSC MRI perfusion and MR spectroscopy. Results: In our study, we found DSC MR perfusion to be a useful non-invasive method for differentiating recurrent brain tumors from radiation necrosis. This approach allows hemodynamic measurements to be obtained within the brain as the relative cerebral blood volume (rCBV) to complement the anatomic information obtained with conventional contrast enhanced MR imaging. The sensitivity and specificity of DSC MR perfusion for differentiation were found to be 77.8% and 80.0%, respectively. Conclusion: DSC MR perfusion is a promising technique in differentiating recurrent brain tumors from radiation necrosis as it has acceptable spatial resolution and can be routinely performed in the same settings after conventional MRI.