Ghost Infarct Core and Admission Computed Tomography Perfusion: Redefining the Role of Neuroimaging in Acute Ischemic Stroke

Abstract

Background: Determining the size of infarct extent is crucial to elect patients for reperfusion therapies. Computed tomography perfusion (CTP) based on cerebral blood volume may overestimate infarct core on admission and consequently include ghost infarct core (GIC) in a definitive lesional area.

Purpose: Our goal was to confirm and better characterize the GIC phenomenon using CTP cerebral blood flow (CBF) as the reference parameter to determine infarct core.

Methods: We performed a retrospective, single-center analysis of consecutive thrombectomies of middle cerebral or intracranial internal carotid artery occlusions considering noncontrast CT Alberta Stroke Program Early CT Score ≥6 in patients with pretreatment CTP. We used the RAPID® software to measure admission infarct core based on initial CBF. The final infarct was extracted from follow-up CT. GIC was defined as initial core minus final infarct > 10 mL.

Results: A total of 123 patients were included. The median National Institutes of Health Stroke Scale score was 18 (13-20), the median time from symptoms to CTP was 188 (67-288) min, and the recanalization rate (Thrombolysis in Cerebral Infarction score 2b, 2c, or 3) was 83%. Twenty patients (16%) presented with GIC. GIC was associated with shorter time to recanalization (150 [105-291] vs. 255 [163-367] min, p = 0.05) and larger initial CBF core volume (38 [26-59] vs. 6 [0-27] mL, p < 0.001). An adjusted logistic regression model identified time to recanalization < 302 min (OR 4.598, 95% CI 1.143-18.495, p = 0.032) and initial infarct volume (OR 1.01, 95% CI 1.001-1.019, p = 0.032) as independent predictors of GIC. At 24 h, clinical improvement was more frequent in patients with GIC (80 vs. 49%, p = 0.01).

Conclusions: CTP CBF < 30% may overestimate infarct core volume, especially in patients imaged in the very early time window and with fast complete reperfusion. Therefore, the CTP CBF technique may exclude patients who would benefit from endovascular treatment.

Keywords: Acute ischemic stroke; Cerebral blood flow; Computed tomography perfusion; Endovascular treatment; Ghost core infarct.

Fig. 1.

Admission CT (a), admission CTP with CBF < 30% (b), initial and post-revascularization angiography (c), and 72-h CT (d) of a 70-year-old male who presented to the emergency department with signs and symptoms of a right total anterior circulation infarct. The NIHSS score at admission was 19. Brain CT presented blurred outlines of right lentiform nucleus and angio-CT revealed occlusion of right internal carotid artery and initial portion (M1) of the right middle cerebral artery with an infarct core of 143 mL based on CBF < 30%. The patient underwent endovascular treatment, with a successful Thrombolysis in Cerebral Infarction score 2b at first pass. The time from symptom onset to CT was 107 min and the time to recanalization was 153 min. After the procedure, the NIHSS score improved to 14 and was 5 on day 5. Follow-up CT on day 3 showed very limited infarct. At 3 months, the modified Rankin Scale score was 2. ASPECTS, Alberta Stroke Program Early CT Score; CBF, cerebral blood flow; CTP, computed tomography perfusion; NIHSS, National Institutes of Health Stroke Scale; TICI, Thrombolysis in Cerebral Infarction.

Fig. 2.

Infarct growth (final infarct volume minus initial core) and time to recanalization. The red line represents time of 302 min. GIC, ghost infarct core.