Large intracranial vessel occlusive vasculopathy after radiation therapy in children: clinical features and usefulness of magnetic resonance imaging.

PURPOSE: To assess the relationship between large intracranial vessel occlusive vasculopathy (vasculopathy) and radiation therapy, and to clarify the clinical efficacy of magnetic resonance (MR) imaging in the diagnosis and screening of the vasculopathy. METHODS AND MATERIALS: We retrospectively evaluated the medical records and serial MR images for 32 pediatric patients, in whom radiation therapy had been given to fields including the circle of Willis and major cerebral arteries. All children had periodically undergone follow-up neurologic assessment and MR imaging examinations at Kanagawa Children's Medical Center for more than one year after radiation therapy (range 1.3-14 years). Patients who had not remained free of tumor progression up to the time of final evaluation were excluded.
RESULTS: Vasculopathy developed in 6 of 32 patients 2-13 years after radiation therapy. Three of them presented with transient ischemic attacks (TIA) and the other three showed infarctions without preceding TIA. Steno-occlusive changes of major cerebral arteries were identified by MR imaging in all six patients, but not obtained in the remaining 26 patients. In the patients with TIA, MR imaging demonstrated steno-occlusive changes at the time of TIA, before irreversible infarction. They have been doing well subsequent to encephaloduroarteriosynangiosis. In the three patients who presented infarction without preceding TIA, MR imaging did not demonstrate the vascular change before the onset of infarction, and two of them developed neurologic deficits. The mean exposure dose for the circle of Willis and major cerebral arteries in these six patients was significantly higher than that in the remaining 26 patients without this sequela (61 Gy vs. 50 Gy, p < 0.05). The mean age at radiation therapy of the six patients was lower, but the difference was not significant.
CONCLUSION: The incidence of vasculopathy after radiation therapy has a considerable correlation with radiation dose and age at radiation therapy. MR examination is useful for the diagnostic evaluation of vasculopathy, and it is also effective in screening for vasculopathy in patients with TIA, and may be helpful in the prevention of neurologic sequela.