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.

The Role of CT Perfusion in Defining the Clinically Relevant Core Infarction to Guide Thrombectomy Selection in Patients with Acute Stroke

“…Recent studies had suggested that CTP core infarct may not necessarily represent irreversibly dead tissue. 11,13 However, multiple factors play a role in this overestimation of infarct core: time from symptom onset to CTP, size of the infarct core, postprocessing software package, the time between CTP and reperfusion, and the completeness of reperfusion are a few of these factors. [15][16][17][18][19] Size of the initial infarct core influences accuracy.…”

“…Earlier studies have suggested that CBV maps reliably predict the final infarct on follow‐up imaging . On the contrary, some other studies have called the reliability of CTP into question …”

“…[6][7][8][9][10] On the contrary, some other studies have called the reliability of CTP into question. [11][12][13] We aimed to investigate whether CTP in acute ischemic stroke patients can accurately measure infarct volume when compared to follow-up MR-DWI.…”

Computed Tomography Perfusion Core Infarct Measurement Compared to Diffusion-Weighted Magnetic Resonance Imaging in Patients with Revascularization of Anterior Circulation, Large Artery Occlusion Ischemic Stroke

“…Prior studies have demonstrated that reduced relative CBF of less than 30% accurately estimates final infarct volume on diffusion-weighted imaging magnetic resonance imaging (DWI MRI) [8], while others have shown ischemic core overestimation with the same parameter, illustrating the so-called "ghost core infarct" concept [9,10]. A more recent trial utilized prospectively collected data from the Highly Effective Reperfusion Evaluated in Multiple Endovascular Stroke Trials (HERMES) and the Tenecteplase Versus Alteplase Before Endovascular Therapy for Ischemic Stroke (EXTEND-IA TNK) trials to retrospectively determine DWI and CTP CBF < 30% differences in patients who achieved early, good revascularization of a LAO [11].…”

Acute Ischemic Stroke: Acute Management and Selection for Endovascular Therapy

“…33 In some cases, particularly in early presentations, CTP may overestimate core infarct size (aka "ghost core"), which could incorrectly deny patients from receiving life-altering therapy. 63,64 For this reason, when the CTP and the ASPECTS are discordant, it is reasonable to proceed to thrombectomy if ASPECTS score is acceptably high, usually ! 6.…”