Usefulness of intravascular pressure ratio measurement for cerebral hemodynamics in carotid artery stenting patients

Figures

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  Fig. 1. Scatterplot showing the relationship between cerebral blood flow asymmetry index (CBF-AI) and cerebral vascular reserve (CVR). Vertical dashed line: CBF-AI threshold (< 0.8); horizontal dashed line: CVR < 10%. These threshold values were adopted based on previously published studies1,4,5,8 indicating their association with cerebral hemodynamic impairment and hyperperfusion risk, and were not newly defined in this study.

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  Fig. 2. Scatterplots illustrating the correlation between carotid pressure ratio (CPR) and key hemodynamic parameters: (A) cerebral blood flow asymmetry index (CBF-AI) (y = 0.18x + 0.83, R2 = 0.23, P < 0.01); (B) diameter of the most severe stenosis (DMS) (mm) (y = 3.10x – 0.31, R2 = 0.27, P < 0.01). (C) the degree of stenosis based on the NASCET method (%) (y = -53.9x + 105, R2 = 0.23, P < 0.01). (D) cerebral vascular reserve (CVR) (%) (y = 72.6x – 12.6, R2 = 0.38, P < 0.01). Each linear regression line represents the trend of the relationship. A statistically significant correlation was observed between CPR and all parameters. R2 values were calculated using simple linear regression analysis to illustrate the strength of linear trends in these relationships. Note: Scatter plots include both pre- and post-stenting values of CPR, DMS, and NASCET stenosis rate to visualize the full spectrum of hemodynamic changes.

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  Fig. 3. Receiver operating characteristic (ROC) curve analysis for the diagnostic performance of CPR and the diameter at most stenosis site (DMS) in predicting impaired cerebral hemodynamics. (A) CPR cutoff of ≤ 0.80 predicted a CVR of less than 10% with an area under the curve (AUC) of 0.91. (B) CPR cutoff of ≤ 0.74 predicted a CBF asymmetry index (CBF-AI) of less than 0.8 with an AUC of 0.77. (C) DMS cutoff of ≥ 1.96 mm predicted a CPR of 1.0 with an AUC of 0.77.

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  Fig. 4. Summary chart displaying the thresholds obtained by receiver operating characteristic analysis for CPR and DMS in predicting hemodynamic impairment. The ranges of CPR and DMS corresponding to specific CVR (< 10%) and CBF-AI (< 0.8) values are highlighted to show progression towards severe hemodynamic impairment. All thresholds were derived using ROC curve analysis, and the optimal cut-off values were identified based on the Youden index to maximize sensitivity and specificity. CPR, carotid pressure ratio; DMS, diameter of the most severe stenosis; CVR, cerebral vascular reserve; CBF-AI, cerebral blood flow asymmetry index.

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  Fig. 5. A 76-year-old man with symptomatic internal carotid artery stenosis. Diffusion-weighted imaging (A) and FLAIR (B) showed findings consistent with a minor stroke. Preoperative SPECT revealed decreased cerebral blood flow (CBF) on the affected side (C: 41.6 mL/100 g/min), with a CBF asymmetry index (CBF-AI) of 0.79 and a cerebrovascular reserve (CVR) of 3% (D). Digital subtraction angiography (DSA) demonstrated a minimum luminal diameter of 1.41 mm preoperatively (E). Pressure recordings showed a clear pressure gradient between the proximal (red arrow) and distal (blue arrow) segments of the stenosis, with a carotid pressure ratio (CPR) of 0.73. After carotid artery stenting, DSA (F) showed improvement of the stenosis to 3.6 mm, and the pressure gradient disappeared, with the CPR improving to 1.02.