Magnetic resonance imaging evaluation of radiation: Cranial radiation therapy-induced diffuse white matter injury

Abstract

e13033 Background: To study the value of MRI in detection and grading of diffuse white matter injury induced by cranial radiation therapy for brain tumors and to evaluate the influence of various risk factors for its development. Methods: This study included 60 patients who had primary brain tumors and received external beam conventionally fractionated radiotherapy. Twenty-three out of 60 patients received chemotherapy after radiotherapy. Post radiotherapy follow-up MRI examination was performed for all patients at 6 weeks, 3, 6, 9, 12 months, and at more than 1 year from completion of radiotherapy. MR imaging was performed with T2-weighted turbo spin echo, fast fluid-attenuated inversion- recovery (FLAIR), T1-weighted spin-echo, and T1-weighted post-contrast spin-echo sequences. Results: Twenty-one of 60 patients (35%) developed diffuse white matter injury at a mean of 15.3 + 7.6 months from the completion of radiotherapy (range, 5–36 months). Radiation-related diffuse white matter changes were characterized as diffuse high signal intensity in the periventricular deep white matter on T2WI and FLAIR sequences. The MRI grading system of these periventricular hyperintensity (PVH) were as follow: 39 patients (65%) had no WMI (grade 0), four had grade 1 changes, three patients had grade 2 changes, nine patients had grade 3, and five patients had grade 4. They were symmetrical in 13 of 21 patients (61.9%), and asymmetrical in eight out of 21 patients (38.1%). The prevalence of diffuse matter injury found to be significantly related to the volume of irradiation (p = 0.02), fraction size (p = 0.008), and concomitant use of chemotherapy (p > 0.02)Conclusions: Diffuse white matter injury is a known consequence of radiation therapy, and the capability of detecting and grading such damage is optimally provided by MRI. No significant financial relationships to disclose.