Sequential detection rates of intramural hematoma for diagnosing spontaneous intracranial artery dissection

Background and purpose: Spontaneous intracranial artery dissection (IAD) can be de-finitively diagnosed by detecting intramural hematoma (IMH) on arterial wall imaging. However, evidence of a time-dependent natural history for the development of radiologi-cal findings is lacking. Therefore, this study aimed to determine when imaging detects IAD.Methods: We obtained data from our cohort databases between March 2011 and August 2018 on consecutive patients who had definite, probable, or possible IAD based on the multidisciplinary expert consensus criteria. We assessed IMH on initial and follow- up high-resolution three-dimensional T1-weighted imaging (HR- 3D-T1WI). We retrospec-tively investigated the association between IMH detection and days from symptom onset to initial HR-3D- T1WI and compared the IMH detection rate with other definitive diag-nostic arterial dissection findings.Results: We analyzed 106 patients (mean age = 51 +/- 13 years, 31 women) with at least initial HR-3D- T1WI data. The final diagnoses were definite, probable, and possible IAD in 83, 18, and 5 patients, respectively. IMHs were observed in 63 patients (59%, 95% con-fidence interval [CI] = 49%- 69%). Overall IMH detection rate was 55% (95% CI = 45%- 64%), 20% (95% CI = 3%- 60%), 40% (95% CI = 21%- 64%), and 50% (95% CI = 37%- 63%) on the initial HR-3D- T1WI and Days 3, 7, and 13, respectively. Among 68 patients evalu-ated with digital subtraction angiography and HR-3D- T1WI, IMH was confirmed more frequently than other definitive diagnostic arterial dissection findings.Conclusions: The overall IMH detection rate on HR-3D- T1WI was > 50% and peaked in 1- 2 weeks. IMH was a frequently detectable finding for the diagnosis of IAD compared to other radiological findings.