Yield of Short-Term Follow-up CT/MR Angiography for Small Aneurysms Detected at Screening

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Abstract
Patients with a history of subarachnoid hemorrhage (SAH) or familial intracranial aneurysms (FIA) are at increased risk for aneurysm formation and rupture. Small aneurysms detected at screening may be left untreated and followed over time. The yield of follow-up CT/MR angiography (CTA/MRA) 1 or 2 years after detection to evaluate growth of these aneurysms is unknown. We prospectively followed patients with small aneurysms detected at screening at a 1-year interval using CTA or MRA. We assessed size, site, and number of the aneurysms and risk factors such as smoking, alcohol use, and hypertension. We evaluated the short-term growth and rupture rate and possible risk factors for growth and rupture. Ninety-three patients (67 with a history of SAH, 16 with FIA, and 10 with a history of both SAH and FIA) with 125 aneurysms underwent CTA/MRA follow-up. Sixty-five patients were followed up once, and 28 patients were followed up twice (median follow-up time, 1.3 years). In 3 of the 93 patients (3.2%), an aneurysm enlarged slightly (0.5 to 1.5 mm). Two patients (2.2%) had a SAH: 1 from an aneurysm at the clip-site from a previous operation that ruptured without enlargement and the other from a newly developed dissecting aneurysm. The only statistically significant risk factor for growth and rupture was a history of both SAH and FIA (relative risk, 10.1; 95% CI, 1.3 to 81.9). The yield of early follow-up of small aneurysms in patients with a history of SAH or FIA is small and does not eliminate the risk of rupture. Whether follow-up at intervals >1 year is useful requires further study.