Is the optimal Tmax threshold identifying perfusion deficit volumes variable across MR perfusion software packages? A pilot study.

Bani-Sadr, Alexandre; Trintignac, Mathilde; Mechtouff, Laura; Hermier, Marc; Cappucci, Matteo; Ameli, Roxana; de Bourguignon, Charles; Derex, Laurent; Cho, Tae-Hee; Nighoghossian, Norbert; Eker, Omer Faruk; Berthezene, Yves

Purpose: Accurate quantification of ischemic core and ischemic penumbra is mandatory for late-presenting acute ischemic stroke. Substantial differences between MR perfusion software packages have been reported, suggesting that the optimal Time-to-Maximum (Tmax) threshold may be variable. We performed a pilot study to assess the optimal Tmax threshold of two MR perfusion software packages (A: RAPID®; B: OleaSphere®) by comparing perfusion deficit volumes to final infarct volumes as ground truth. Methods: The HIBISCUS-STROKE cohort includes acute ischemic stroke patients treated by mechanical thrombectomy after MRI triage. Mechanical thrombectomy failure was defined as a modified thrombolysis in cerebral infarction score of 0. Admission MR perfusion were post-processed using two packages with increasing Tmax thresholds (≥ 6 s, ≥ 8 s and ≥ 10 s) and compared to final infarct volume evaluated with day-6 MRI. Results: Eighteen patients were included. Lengthening the threshold from ≥ 6 s to ≥ 10 s led to significantly smaller perfusion deficit volumes for both packages. For package A, Tmax ≥ 6 s and ≥ 8 s moderately overestimated final infarct volume (median absolute difference: – 9.5 mL, interquartile range (IQR) [– 17.5; 0.9] and 0.2 mL, IQR [– 8.1; 4.8], respectively). Bland–Altman analysis indicated that they were closer to final infarct volume and had narrower ranges of agreement compared with Tmax ≥ 10 s. For package B, Tmax ≥ 10 s was closer to final infarct volume (median absolute difference: – 10.1 mL, IQR: [– 17.7; – 2.9]) versus – 21.8 mL (IQR: [– 36.7; – 9.5]) for Tmax ≥ 6 s. Bland–Altman plots confirmed these findings (mean absolute difference: 2.2 mL versus 31.5 mL, respectively). Conclusions: The optimal Tmax threshold for defining the ischemic penumbra appeared to be most accurate at ≥ 6 s for package A and ≥ 10 s for package B. This implies that the widely recommended Tmax threshold ≥ 6 s may not be optimal for all available MRP software package. Future validation studies are required to define the optimal Tmax threshold to use for each package.

INTEGRATED software; ISCHEMIC stroke; PERFUSION; STROKE patients; CEREBRAL infarction; ISOLATION perfusion

MAGMA: Magnetic Resonance Materials in Physics, Biology & Medicine, 2023, Vol 36, Issue 5, p815

0968-5243

Academic Journal

10.1007/s10334-023-01068-0