Dynamic susceptibility contrast-enhanced perfusion MR imaging in late radiation-induced injury of the brain.

The objective of the study was to evaluate radiation-induced cerebral injury on dynamic susceptibility contrast-enhanced (DSCE) perfusion MR imaging and study its relationship with morphological severity and disease progression. Thirty-one patients with known radiation injury to the temporal lobes where studied. Gradient and spin-echo T2-weighted, gadolinium-enhanced T1-weighted and DSCE perfusion MR imaging were obtained in the coronal plane through the anterior temporal lobe. Regions of interest where selected in the anterior temporal lobes and the superior frontal lobe as control for analysis of perfusion parameters. The mean transit time (MTT) was prolonged in both the High Dose Zone (HDZ) receiving from two-thirds to the total dose of 66-71.2 Gy, and the Intermediary Dose Zone (IDZ) receiving up to 87% of the total dose. The HDZ but not the IDZ showed a low relative cerebral blood volume (rCBV) and relative cerebral blood flow index (rCBFi). The rCBV and rCBFi were significantly lower in both HDZ and LBZ in temporal lobes with severe lesions compared to the temporal lobes with mild lesions but there was no significant difference in bolus transit parameters. The rCBV and rCBFi were significantly lower in both HDZ and IDZ of the swollen temporal lobes compared to those without swelling. It was concluded that DSCE perfusion MR imaging demonstrated a derangement in perfusion in radiation-induced cerebral injury in rCBV, rCBFi and MTT, which were related to the severity of the radiation-induced injury and the dose of irradiation delivered.