Related Experiment Video
Updated: May 6, 2026
A Magnetic Resonance Imaging Protocol for Stroke Onset Time Estimation in Permanent Cerebral Ischemia
Published on: September 16, 2017
Perfusion stability in acute stroke: An observational study exploiting repeated CTP imaging
Alexander Rau1, Ömer Bagcilar1, Marco Reisert2,3
1Department of Neuroradiology, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany.
Background And Purpose:
CT perfusion (CTP) is widely used to assess infarct core in acute stroke, yet real-world data on its reproducibility and temporal dynamics are limited.
Materials And Methods:
We retrospectively identified patients with repeated CTP scans. Core and hypoperfusion volumes were quantified using standard thresholds (CBF <30 %, Tmax >6 s). Clinical and imaging data were reviewed to identify cases with disruptive events. We analyzed scan-to-scan differences in core volume, hypoperfusion volume, ASPECTS, and intensity metrics, including median Tmax (in hypoperfusion), CBF, and NCCT HU (in core), using Bland-Altman analysis and assessed their association with time between scans.
Results:
Among 32 patients with repeated CTP (26 with repeated NCCT), three were excluded due to disruptive events. In the remaining 29 cases, mean scan-to-scan differences for infarct core volume (4.8 ± 19.6 mL), hypoperfusion volume (3.86 ± 39.1 mL), and ASPECTS (-0.4 ± 1.6) indicated minimal systematic bias at the group level but substantial variability. Correlation coefficients were high (r = 0.90, 0.93, and 0.70, respectively; all p < 0.0001), and no statistically significant paired differences or association with scan interval were observed. Intensity-based metrics likewise showed minimal bias with lower variability (Tmax -0.3 ± 1.07 s; CBF -3.11 ± 7.3 %; NCCT HU -3.0 ± 4.9 %), high correlations (Tmax r = 0.87, CBF r = 0.91, NCCT HU r = 0.69; all p < 0.02), and no association with time between scans.
Conclusions:
Repeated CTP showed no systematic group-level scan-to-scan bias suggestive of infarct growth, while a substantial degree of variability was observed, with intensity-based metrics demonstrating lower variability than volume estimates. These findings support temporal consistency of perfusion-derived metrics at the group level and question the applicability of linear infarct growth rate (IGR) concepts to perfusion imaging, which primarily reflects a hemodynamic state rather than time-dependent tissue progression.
