Optimizing temporal resolution to reduce radiation dose in cerebral perfusion CT: a feasibility and stability study based on perfusion parameter assessment

To investigate the feasibility of reducing radiation dose in cerebral perfusion CT (CTP) while maintaining diagnostic accuracy by optimizing temporal resolution.

This retrospective cohort study included 117 stroke-suspected patients undergoing CTP at the First Affiliated Hospital of Army Medical University from January to September 2025. Three protocols were designed: Protocol 1 (full temporal resolution, 21-phase acquisition, baseline), Protocol 2 (every-other-phase sampling), Protocol 3 (peak-enhancement+1/-1 phase retention with every-other-phase sampling for remaining phases). Radiation reduction percentages relative to Protocol 1 were calculated. Regions of interest (ROI) were placed in ischemic core/penumbra to measure mean±SD of perfusion parameters: time to maximum of the residue function (Tmax), mean transit time (MTT), cerebral blood volume (CBV) and cerebral blood flow (CBF). Inter-protocol differences were assessed, and ischemic penumbra volume discrepancies were also analyzed.

Protocol 2 and 3 reduced radiation dose by 50.0% and 42.9% versus Protocol 1, respectively. For perfusion parameters: Tmax SD differed significantly across protocols [F(1.92, 222.42)=11.17, P<0.001, partial η²=0.09]; post hoc tests showed significant mean differences between Protocol 1 vs 2 (P<0.016 7) and Protocol 1 vs 3 (P<0.016 7), but not Protocol 2 vs 3. MTT means showed no significant difference [F(1.88, 218.11)=0.47, partial η²=0.004], though SD differed significantly between Protocol 1 vs 2 and 1 vs 3 (P<0.016 7). CBV SD differed significantly [F(1.98, 229.25)=22.97, P<0.001, partial η²=0.17] with no mean difference (Friedman test). CBF means showed no significant difference (Bonferroni-adjusted) but SD differed significantly between Protocol 1 vs 2 and 1 vs 3 (P<0.016 7). Ischemic penumbra volumes differed significantly across all protocols (P<0.016 7).

Temporal resolution optimization significantly reduces CTP radiation dose while minimally impacting core perfusion parameters (MTT, CBV, CBF means). CBF remained stable across reduced-dose protocols and may serve as a reliable diagnostic criterion for infarct core delineation.