Evolution of acute lacunar lesions in terms of size and shape: a PICASSO sub-study

The imaging definition of lacunar infarcts is variable, particularly regarding their size and the presence of cavitation. We investigated the changes of diameter and evolution pattern of acute lacunar infarcts, and the factors associated with the evolution pattern. Patients with acute single subcortical hemispheric or brainstem ischemic lesions of penetrating arterial territories were included. Maximal diameters on initial diffusion-weighted image (DWI) and follow-up fluid-attenuated inversion recovery image (FLAIR), which performed > 12 months after initial DWI, were semi-automatically measured. Clinical characteristics were compared according to evolution patterns on follow-up FLAIR, classified as cavitated, focal lesion without cavitation, and disappeared. Five hundred nine patients were included. Mean time to follow-up was 31.3 ± 13.7 months. Mean diameter of acute lacunar lesions decreased from 12.9 ± 4.4 to 8.5 ± 4.8 mm during follow-up. Lesions of 58.2% patients remained as cavitated, 18.3% as focal lesion without cavitation, and 23.6% disappeared. Initial NIHSS score (p = 0.005), diameter of initial lesion (p < 0.001), number of slices showing acute lesion on DWI (p < 0.001), progression of white matter lesion (p < 0.001), number of acute lesions involving gray matter (p = 0.008) and lesion location (p < 0.001) were different among three groups. After adjustment for covariates, diameter of the acute lesion, initial number of old lacunes, and anterior lesion location were associated with the appearance of cavitation. Initial lesion diameter and posterior lesion location were associated with the disappearance. We observed reduction of the acute lacunar lesion diameter in 86%. There were predictive factors of disappearance and cavitation of acute lacunar infarction.