Prevalence and Clinical Implications of Hemosiderin Deposits in Recent Small Subcortical Infarcts

Abstract

Background and objectives: A quarter of ischemic strokes are of lacunar clinical subtype and have an underlying recent small subcortical infarct (RSSI), but their long-term outcomes remain poorly characterized. Hemosiderin deposits (HDs) have been noted in RSSIs at chronic stages and might mimic primary hemorrhage. We characterized HDs' morphology, frequency, and clinical relevance.

Methods: Participants with RSSIs were identified from a prospective longitudinal study and evaluated on 3T MRI including susceptibility-weighted imaging (SWI) from stroke diagnosis to 12 months. We categorized HDs in RSSIs on SWI at all available time points into 4 types (spots, smudge, rim, cluster) and assessed their associations with demographic factors, stroke-related factors, and image markers with adjusted logistic regression.

Results: HDs were observed in 43 (55.0%) of 108 participants within 3 months and 83 (76.9%) of 108 within 12 months after stroke onset. The mean time to first detection of HDs was 87 (interquartile range 53-164) days. A "rim" pattern (similar to late appearance of primary hemorrhage) occurred in at least 26.5% of RSSIs at all follow-up time points, mainly those located in the lentiform/internal capsule (50.0%) or thalamus (36.4%). Infarct volume (odds ratio [OR] 1.003, 95% CI 1.001-1.006; p = 0.004) and the total small vessel disease (SVD) score at baseline (OR 2.50, 95% CI 1.28-4.86, p = 0.007) independently predicted HDs at 12 months. HDs were positively associated with more lacunes (OR 1.60, 95% CI 1.13-2.26, p < 0.01), but not the Fazekas score, number of microbleeds, basal ganglia mineral deposit score, or clinical outcomes.

Discussion: HDs occur commonly in RSSIs and may be associated with infarct volume and SVD score. Hemosiderin "rim" is common in RSSIs, urging caution to avoid mistaking ischemic RSSI for primary hemorrhage in subacute and chronic stages.

Figure 1. Morphologies and Description of Hemosiderin Deposits

CMB = cerebral microbleed; SWI = susceptibility-weighted imaging.

Figure 2. Categories and Evolution of HDs

Figure 2A illustrates the quantity change of different HD patterns at the baseline, 6-month, and 12-month follow-ups. Figure 2B shows the increased positive rates of HDs in 4 areas at 3 time-point visits. HD = hemosiderin deposit.

Figure 3. Morphology and Evolution of Hemosiderin Deposits

(A–E) In a patient with an infarct in the basal ganglia, the “rim” pattern developed and became more obvious and thicker along the follow-ups. (F–J) In a patient with a RSSI adjacent to the lateral ventricle, the “smudge” became larger at 3-month and 6-month visits but shrank and turned darker, “condensed,” at the 12-month visit. (K–O) A “cluster” pattern in another RSSI adjacent to the lateral ventricle and the number of dots and lines became more visible inside and around the infarct during follow-up. DWI = diffusion-weighted imaging; RSSI = recent small subcortical infarct.