Detection of hemorrhagic hypointense foci in radiation injury region using susceptibility-weighted imaging

Background: Susceptibility-weighted imaging (SWI), a novel, highly sensitive 3D gradient echo MR imaging technique, is used to detect hemorrhage. Purpose: To evaluate SWI at 3.0T for detection and visualization of hemorrhage at radiation injury region after radiotherapy for brain glioma. Material and Methods: In 16 patients who had radiation injury in the vicinity of the previously resected and irradiated high-grade brain glioma, SWI examinations were performed on a 3T MR scanner. The presence of intralesional hypointense foci on SWI was evaluated by two neuroradiologists. Frequency of these foci on SWI was assessed and the number of these foci was counted. Diagnosis of radiation injury was assigned by means of histopathology or follow-up MR image. Results: In all 16 cases with cerebral radiation injury, nine were verified by means of histopathologic examination, seven by follow-up image. While in one patient quality of SWI was poor, in all remaining patients diagnostic-quality SWI was obtained. The intralesional hypointense foci were detected in 12 of 15 patients. These hypointense foci were nodular, angular, or tubular regions of low signal intensity on SWI. The distribution of these foci was diffusive (n = 5) or scattered (n = 7). Number of these foci per cm(2) on SWI was 7.25 +/- 3.67. Conclusion: SWI is a novel and promising technique for evaluation of hemorrhage at radiation injury regions in the vicinity of the previously treated gliomas.