Assessment of computed tomography perfusion software in predicting spatial location and volume of infarct in acute ischemic stroke patients: a comparison of Sphere, Vitrea, and RAPID

Abstract

BackgroundCT perfusion (CTP) infarct and penumbra estimations determine the eligibility of patients with acute ischemic stroke (AIS) for endovascular intervention. This study aimed to determine volumetric and spatial agreement of predicted RAPID, Vitrea, and Sphere CTP infarct with follow-up fluid attenuation inversion recovery (FLAIR) MRI infarct.Methods108 consecutive patients with AIS and large vessel occlusion were included in the study between April 2019 and January 2020 . Patients were divided into two groups: endovascular intervention (n=58) and conservative treatment (n=50). Intervention patients were treated with mechanical thrombectomy and achieved successful reperfusion (Thrombolysis in Cerebral Infarction 2b/2 c/3) while patients in the conservative treatment group did not receive mechanical thrombectomy or intravenous thrombolysis. Intervention and conservative treatment patients were included to assess infarct and penumbra estimations, respectively. It was assumed that in all patients treated conservatively, penumbra converted to infarct. CTP infarct and penumbra volumes were segmented from RAPID, Vitrea, and Sphere to assess volumetric and spatial agreement with follow-up FLAIR MRI.ResultsMean infarct differences (95% CIs) between each CTP software and FLAIR MRI for each cohort were: intervention cohort: RAPID=9.0±7.7 mL, Sphere=−0.2±8.7 mL, Vitrea=−7.9±8.9 mL; conservative treatment cohort: RAPID=−31.9±21.6 mL, Sphere=−26.8±17.4 mL, Vitrea=−15.3±13.7 mL. Overlap and Dice coefficients for predicted infarct were (overlap, Dice): intervention cohort: RAPID=(0.57, 0.44), Sphere=(0.68, 0.60), Vitrea=(0.70, 0.60); conservative treatment cohort: RAPID=(0.71, 0.56), Sphere=(0.73, 0.60), Vitrea=(0.72, 0.64).ConclusionsSphere proved the most accurate in patients who had intervention infarct assessment as Vitrea and RAPID overestimated and underestimated infarct, respectively. Vitrea proved the most accurate in penumbra assessment for patients treated conservatively although all software overestimated penumbra.

Enhancing performance of a computed tomography perfusion software for improved prediction of final infarct volume in acute ischemic stroke patients

“…6 Although CTP is relied upon to assess reperfusion eligibility, multiple CTP software products exist that utilize different perfusion parameters and thresholds for identifying infarct and penumbra tissue. 7,8 The aforementioned perfusion parameters are calculated using arterial input function (AIF) and venous output function (VOF) curves. The AIF and VOF locations are automatically selected within the CTP volume as a feeding artery and a draining vein, respectively.…”

“…9,10 RAPID (iSchemaView, Menlo Park, CA, USA) and Sphere (Olea Medical, La Ciotat, France) CTP software are two commercially available software products that primarily rely on the CBF parameter, but utilize different contralateral hemisphere thresholds to identify infarct. 8,11 Reliance on the CBF parameter can, however, lead to false positive identification of infarct in regions of leukoaraiosis. This decrease in CBF, allowing for the segmentation of infarct, is due to white matter naturally having lower amount of blood flow than gray matter, especially in regions of leukoaraiosis.…”

“…12,13 Meanwhile, Vitrea and recently developed CTPþ (Vital Images, Minnetonka, MN, USA) software primarily rely on CBV to identify infarct. 8 Although previous studies have been conducted assessing the reliability of infarct and penumbra segmentation using RAPID, Sphere, and Vitrea, similar studies need to be conducted on the recently developed CTPþ software. 7,8,11,12,14 We aimed to assess the agreement of FIVs and penumbra between DWI and the newly developed CTPþ software.…”

“…8 Although previous studies have been conducted assessing the reliability of infarct and penumbra segmentation using RAPID, Sphere, and Vitrea, similar studies need to be conducted on the recently developed CTPþ software. 7,8,11,12,14 We aimed to assess the agreement of FIVs and penumbra between DWI and the newly developed CTPþ software. Additionally, infarct and penumbra volumes from CTPþ were compared with commercially available RAPID and Sphere, along with CTPþ's predecessor, Vitrea.…”

Effect of computed tomography perfusion post-processing algorithms on optimal threshold selection for final infarct volume prediction

“…10,11 Recently, Bayesian algorithms have been developed, which are based on a probabilistic approach reliant on neighboring regions of perfusion scans and noise reduction to generate perfusion maps. [12][13][14][15] Calculation differences potentially result in discrepancies in perfusion maps, preventing a standard infarct and penumbra identification protocol from being implemented across all CTP software and vendors. 16 This can be dangerous to patients, as overestimating infarct can lead to exclusion from thrombectomy procedures and underestimating infarct can lead to reperfusion injuries.…”