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

Abstract

Background and Purpose-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. Methods-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. Results-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). Conclusions-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 Ͼ1 year is useful requires further study.

Risk Factors for Growth of Intracranial Aneurysms: A Systematic Review and Meta-Analysis

“…Twenty-one studies reported risk factors for aneurysm growth, including 3954 patients with 4990 aneurysms with 11,000 patient-years and 13,294 aneurysm-years of follow-up. 9,12,[15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] Eleven of these studies reported the rupture rate of growing aneurysms. Mean patient follow-up was 4.9 years, and median was 3.2 years.…”

“…4 A number of large longitudinal studies on the risk factors of aneurysmal rupture have been performed, which have enhanced our understanding of the natural history of unruptured aneurysms. 7,9,10,22,33,[36][37][38][39] Overall rupture rates in these studies range from 1% to 1.4% per year. 9,10,36,37 Clinical risk factors for aneurysm rupture in these studies included hypertension, smoking, aneurysm multiplicity, prior history of SAH, family history, and female sex.…”

MR Angiography Follow-Up 5 Years after Coiling: Frequency of New Aneurysms and Enlargement of Untreated Aneurysms

“…However, during the first 33 months, no recurrent SAH was observed from de novo or regrowth aneurysms. In another study, 7 short-term (1-2 years) CTA follow-up of small aneurysms detected at screening in patients with a history of SAH or with familial aneurysms did not eliminate the risk of recurrent SAH: Two of 93 patients had a recurrent SAH, 1 from the clipped aneurysm and 1 from a new dissecting aneurysm. In that study, in 3 of 93 patients, the small aneurysm detected at screening had enlarged slightly.…”

“…In particular, the time period after which screening for these events could be effective is unknown. [7][8][9] In a recent study of 610 patients with ruptured aneurysms that were clipped, after 2-18 years of follow-up, de novo aneurysms had developed in 3% of patients and 25% of untreated additional aneurysms had enlarged. 2 Because follow-up intervals varied widely, the time of first development or growth remained obscure.…”

Bone-Subtraction CT Angiography: Evaluation of Two Different Fully Automated Image-Registration Procedures for Interscan Motion Compensation

“…[1][2][3][4][5][6][7][8][9] The resulting datasets are usually visualized by means of maximum intensity projection (MIP) or volume rendering. A limitation of rendered CTA is that vessels surrounded by bone and calcification can be obscured.…”