Haemosiderin Deposits Sign on Susceptibility-Weighted Imaging in Recent Small Subcortical Infarcts

Abstract

Introduction: The long-term evolution of recent small subcortical infarcts (SSIs) remains insufficiently characterized. Previous studies have indicated haemosiderin deposits (HD) in SSIs during their subacute and chronic stages. Our study aims to provide a comprehensive description of the morphology and evolution of HD in SSI and explore associated factors. Methods: We enrolled 140 patients with SSI from the Mild Stroke Study 3 (MSS3). Using susceptibility-weighted imaging (SWI), we categorized HD in SSI into five types: none, spots, smudge, rim, and lines/dots around the infarct. The evolution types were classified as single type or mixed type. Over a one-year follow-up period, we examined the evolution of per-infarct associations with HD type and identified influencing factors. Results: Out of the 119 enrolled SSI patients (mean age: 64.3±11.4 years, 80 men [67.2%]), we analyzed 141 small subcortical infarcts, excluding 5 due to motion artifacts or lack of MR scanning at the six-month and one-year follow-ups. During the one-year follow-up, we observed HD in 101 infarcts, with the percentage of HD increasing from 55.0% at baseline to 100% at the one-year follow-up. The predominant initial HD type was smudge, and the main evolution types were retaining smudge of the single type (32.8%) and smudge with rim in the mixed type (23.3%). Logistic regression analysis revealed that infarct volume (OR=1.55, 95% CI 1.13-2.14; P=0.007) and location (basilar ganglia: OR=5.13, 95% CI 1.26-20.83; P=0.022; centrum semiovale: OR=4.125, 95% CI 1.07-15.86, P=0.039) were independent predictors of HD on SWI. Discussion: The presence of HD in SSI detected through SWI may be associated with the volume and location of infarct the infarct. The classification of HD and its evolution hold clinical significance in differentiating an infarct from a primary hemorrhage during the subacute and chronic periods.