Dimensions of Subcortical Infarcts Associated with First- to Third-Order Branches of the Basal Ganglia Arteries

Abstract

Background: It has been described that lacunar infarct is characterized by its smallish size (15-20 mm) in the axial plane. However, the size of the basal ganglia artery responsible for this type of infarct is uncertain. Detection of small arterial occlusion is not possible with current angiography, hindering correlation of arterial occlusion with subcortical infarct size. Recently, investigators have published microangiographic templates of arteries supplying the basal ganglia. These templates display first-order (proximal) to third-order (distal) branching of these arteries and can help with estimating the likely site of arterial disease in subcortical infarcts. We correlated the dimensions of subcortical infarcts with the order of arterial branching described in a microangiographic template. Such data may provide further clues about the type of arteries associated with subcortical infarcts and assist in refining the concept of lacunar infarction. Method: Patients with subcortical infarcts on MR imaging (MRI) admitted to our institution between 2009 and 2011 were included in the study. Infarcts were manually segmented and registered to a standard brain template. These segmented infarcts were scaled and overlapped with published microangiographic templates, and used by 6 raters who independently estimated the branching order of arterial disease that might result in these infarcts. We used regression analysis to relate these ratings to infarct dimensions. Results: Among 777 patients, there were 33 (58% male) patients with subcortical infarcts. The mean age was 63.1 ± 15.1 years. Infarct dimensions for the groups were as follows: group 1 (first-order branch): height 37.6 ± 7.4 mm, horizontal width 21.2 ± 11.6 mm, anterior-posterior length 36.8 ± 20.1 mm; group 2 (second-order branch): height 25.2 ± 7.9 mm, horizontal width 16.6 ± 22.8 mm, anterior-posterior length 16.1 ± 8.0 mm; group 3 (third-order branch): height 11.6 ± 5.7 mm, axial width 5.3 ± 3.1 mm, anterior-posterior length 5.5 ± 3.8 mm. Increasing vessel branching order (from large to small vessels) was linearly and negatively associated with infarct height (β = -16.7 mm per change in branching order disease, 95% CI -20.3, -13.1 mm, p < 0.01) and anterior-posterior length (β = -16.8 mm per change in branching order disease, 95% CI -23.2, -10.5 mm, p < 0.01). Discussion: Based on MRI infarct dimensions and a microangiographic template, it may be possible to estimate the branching order of the artery involved in subcortical infarcts. Further, our small data set suggests that reliance on an axial dimension of 15-20 mm may not be the best approach to classifying lacunar infarct. This finding needs to be confirmed in a larger data set.

White matter hyperintensity lesion burden is associated with the infarct volume and 90-day outcome in small subcortical infarcts

“…The overall number of included patients was modest but consistent with the sample size of prior investigations of SSI (3,33,34); and to our knowledge the only study utilizing CCS-based stroke classification which has the major advantage that it minimizes rater bias by integrating multiple aspects of ischemic stroke evaluation in a probabilistic and objective manner and it is increasingly used in scientific investigations, which allows for more reliable comparison of our findings with other investigations using the same classification system. Nevertheless, a possible limitation of the CCS relates to the fact that it may incorrectly classify some patients with multiple SSI to have a non-SVD related stroke mechanism, which may not be uniformly the case (12,35).…”

Examining Subcortical Infarcts in the Era of Acute Multimodality CT Imaging

“…The lack of collaterals among these small arteries may account for the discrete small subcortical infarcts (29). Using arterial templates from this study, our group had previously estimated the size of the infarct related from first- to third-order branches of the penetrating arteries such as the lenticulostiate arteries (31). In that study, the presence of lacunar mechanism was higher among those with infarcts of third-order branches (mean axial diameter ~5.3 mm and volume ~0.7 ml) than infarcts of first order branch (mean axial diameter ~21.2 mm and volume ~20.5 ml) (31).…”

“…The median size of lacunar infarcts in the SPS3 trials ranged from 0.40 to 0.90 ml (25). A possible inference from these works is that the size of the perfusion deficit would remain confine to subcortical region of the artery and would not spread remote from this arterial territory such as to the cortical region (29, 31). However, if there is occlusion proximal to perforating artery rather than distal part of the perforating artery then perfusion deficit may spread to the cortical region.…”

“…This infarct volume would approximate to occlusion of second order branches of the penetrating arteries (31). …”

Arterial branching and basal ganglia lacunes: A study in pure small vessel disease

“…11 Raters were asked to visually estimate the branching order of the artery related to the lacune, and whether the vessel that was likely to have been diseased was a first-, second-or third-order branch, or out with the LSA/RAH territory.…”