Perfusion Deficits and Mismatch in Patients with Acute Lacunar Infarcts Studied with Whole-Brain CT Perfusion

BACKGROUND AND PURPOSE:The incidence and significance of perfusion abnormalities on brain imaging in patients with lacunar infarct are controversial. We studied the diagnostic yield of CTP and the type of perfusion abnormalities in patients presenting with a lacunar syndrome and in those with MR imaging–confirmed lacunar infarcts.MATERIALS AND METHODS:A cohort of 33 patients with lacunar syndrome underwent whole-brain CTP on admission. Twenty-eight patients had an acute ischemic lesion at follow-up MR imaging; 16 were classified as lacunar infarcts. Two independent readers evaluated NCCT and CTP to compare their diagnostic yield. In patients with DWI-confirmed lacunar infarcts and visible deficits on CTP, the presence of mismatch tissue was measured by using different perfusion thresholds.RESULTS:The symptomatic acute lesion was seen on CTP in 50% of patients presenting with a lacunar syndrome compared with only 17% on NCCT, and in 62% on CTP compared with 19% on NCCT, respectively, in patients with DWI-confirmed lacunar infarcts. CTP was more sensitive in supratentorial than in infratentorial lesions. In the nonblinded analysis, a perfusion deficit was observed in 12/16 patients with DWI-confirmed lacunar infarcts. The proportion of mismatch tissue was similar in patients with lacunar infarcts or nonlacunar strokes (32% versus 36%, P = .734).CONCLUSIONS:Whole-brain CTP is superior to NCCT in identifying small ischemic lesions, including lacunar infarcts, in patients presenting with a lacunar syndrome. Perfusion deficits and mismatch are frequent in lacunar infarcts, but larger studies are warranted to elucidate the clinical significance of these CTP findings.

Small-vessel disease is common and causes cognitive, psychiatric, and physical disability.¹ Lacunar infarcts (LIs) are one of the main manifestations of small-vessel disease, accounting for 10%–20% of all ischemic strokes, and they often present with the characteristic classic lacunar syndromes: pure motor hemiparesis, pure sensory stroke, sensorimotor stroke, ataxic hemiparesis, and dysarthria–clumsy hand syndrome. LIs are usually <1.5 cm wide and are often located in the territory of deep perforating arteries such as lenticulostriate, thalamoperforant, or paramedian territories. However, LIs can also result from in situ occlusion of single superficial perforators from pial arteries. LIs are thought to be related to arteriopathy of small blood vessels in the brain, either because of lipohyalinosis or microatheroma.² Less frequent causes are stenosis of a large vessel or microembolization.The sensitivity of neuroimaging techniques in acute LI is variable, ranging from 40% for NCCT scans,^3,4 80% for MR imaging,⁵ and up to 94% for DWI.⁶ Conflicting results have been reported regarding the presence of perfusion deficits in patients with LI,^7–11 with sensitivities varying from 0% to 68% in studies using MR imaging^12–14 and from 17% to 47% with CTP.^15,16 In fact, LI is considered one of the causes of false-negative CTP findings.^10,11 Some reports suggest that the presence of a perfusion deficit is associated with worse outcome in patients with LIs.^8,13 Regarding the presence of mismatch, a study using perfusion MR imaging did not find a mismatch between perfusion and diffusion sequences in strokes involving perforating arteries, but these results could be explained by the low resolution of their imaging methods.¹²In this study, we first assessed the clinical utility of CTP in the real-life scenario of patients presenting to the emergency department with a lacunar syndrome. Then, we studied the details of the perfusion abnormalities in a subgroup of patients with MR imaging–confirmed LIs and compared them with those of patients with nonlacunar infarcts.