Detection of cavernous malformations after whole-brain radiotherapy in primitive neuroectodermal tumor patients-comparing susceptibility-weighted imaging and T2 gradient-echo sequences.

Purpose: The aim of this retrospective study is to investigate the value of the susceptibility-weighted imaging (SWI) sequence compared to gradient echo (GRE) in the detection and follow-up of cavernous malformations in patients who underwent whole-brain irradiation as part of their medulloblastoma treatment.

Methods: We retrospectively examined MRI studies of 28 subjects (16 males, 12 females) who received whole-brain irradiation as part of their treatment. Ages at irradiation ranged from 2 to 38 years. All patients were periodically followed up with MR imaging (ranging from 9 to 336 months). Two neuroradiologists reviewed studies of the same patients, comparing the number of suspected cavernomas detected on GRE and SWI sequences performed at different times (median time between studies, 10 months).

Results: Hypointense lesions were detected in 24 subjects on SWI sequences and in 19 subjects on GRE sequences. More lesions were seen on SWI than on GRE (p = 0.006). Four patients had no detectable lesions. The minimal period from irradiation to first lesion detection was 14 months. Cavernomas larger than 3 mm were detected in 14 subjects by both GRE and SWI. None of the subjects had symptoms related to cavernomas.

Conclusions: The sensitivity of SWI in the detection of hypointense lesions in patients after whole-brain irradiation is significantly higher than that of the GRE sequence. It appears that almost all subjects eventually develop small hypointense lesions after radiotherapy, and some of them progress to cavernous malformations. The clinical significance of the increased sensitivity of SWI in this group of patients is not entirely certain.