CT Perfusion in Acute Lacunar Stroke: Detection Capabilities Based on Infarct Location

BACKGROUND AND PURPOSE:Recent studies demonstrated superiority of CTP to NCCT/CTA at detecting lacunar infarcts. This study aimed to assess CTP''s capability to identify lacunae in different intracranial regions.MATERIALS AND METHODS:Over 5.5 years, 1085 CTP examinations were retrospectively reviewed in patients with acute stroke symptoms with CTP within 12 hours and MRI within 7 days of symptom onset. Patients had infarcts ≤2 cm or no acute infarct on DWI; patients with concomitant infarcts >2 cm on DWI were excluded. CTP postprocessing was automated by a delay-corrected algorithm. Three blinded reviewers were given patient NIHSS scores and symptoms; infarcts were recorded based on NCCT/CTA, CTP (CBF, CBV, MTT, and TTP), and DWI.RESULTS:One hundred thirteen patients met inclusion criteria (53.1% female). On DWI, lacunar infarcts were present in 37 of 113 (32.7%), and absent in 76 of 113 (67.3%). On CTP, lacunar infarcts typically appeared as abnormalities larger than infarct size on DWI. Interobserver κ for CTP ranged from 0.38 (CBF) (P < .0001) to 0.66 (TTP) (P < .0001); interobserver κ for DWI was 0.88 (P < 0.0001). In all intracranial regions, sensitivity of CTP ranged from 18.9% (CBV) to 48.7% (TTP); specificity ranged from 97.4% (CBF and TTP) to 98.7% (CBV and MTT). CTP''s sensitivity was highest in the subcortical white matter with or without cortical involvement (21.7%–65.2%) followed by periventricular white matter (12.5%–37.5%); sensitivity in the thalami or basal ganglia was 0%.CONCLUSIONS:CTP has low sensitivity and high specificity in identifying lacunar infarcts. Sensitivity is highest in the subcortical white matter with or without cortical involvement, but limited in the basal ganglia and thalami.

Lacunar infarcts are ischemic insults that predominantly result from the occlusion of single perforating arteries.¹ Typically, lacunae occur within the thalami, basal ganglia, brain stem, corona radiata, or internal capsule.^2–4 Although lacunar infarcts predominantly occur secondary to small vessel disease, other etiologies such as cardiac emboli and vasculitis also have been described.⁵ Lacunar strokes are a common cause of morbidity and account for up to 25% of all ischemic strokes.^6,7 Classically, symptoms of lacunar infarcts include pure sensory syndrome, pure motor hemiparesis, sensorimotor stroke, ataxic hemiparesis, or dysarthria-clumsy hand syndrome.^2,8 Thrombolytic therapy has been shown to be effective in the treatment of acute lacunar stroke, making the timely and accurate diagnosis of lacunar infarcts of utmost importance.⁹NCCT is less sensitive than DWI in the detection of lacunar strokes, with reported sensitivities ranging from 0%–35% for NCCT and 75%–95% for DWI.^10–13 Nevertheless, because CT remains more accessible than MR imaging in emergency settings, its optimization in the diagnosis of stroke continues to be vital.¹⁴ Recently, CTP has been shown to be superior to NCCT and CTA in assessing for lacunar infarcts.^4,15 However, neither of the recent studies directly compared CTP with NCCT/CTA in the detection of lacunae: Rudilosso et al¹⁵ assessed the use of CTP in patients with clinical lacunar syndrome, and Das et al⁴ investigated the use of CTP as part of a multimodal approach in the setting of lacunar infarction, noting only that 61% of patients had an abnormality on CTP concordant with infarction on DWI. Furthermore, neither study investigated CTP''s capability to detect lacunae within specific regions of the brain.The purpose of this study was to compare the diagnostic performance of CTP with NCCT/CTA in the identification of acute lacunar infarcts and evaluate the diagnostic capabilities of CTP in the detection of lacunar strokes within different areas of the brain.