Abstract WP137: A CT Perfusion Based Computational Modeling for Improved Risk Stratification of Haemodynamically Significant ICAD

Abstract

Aim: In endovascular ICAD treatment, an individualized patient-specific treatment pathway may be very helpful. Patient selection for endovascular treatment based on anatomical markers has not been shown to be effective in past clinical trials. This pilot study combines CT perfusion (CTP) analysis and computational fluid dynamics to identify hemodynamically significant patients for a reliable pathway for intervention planning. Methods: We assessed patients from two stroke centers with 50-99% ICAD lesions. Using a novel technique, CTP scans generated acute vascular territory maps for major cerebral arteries (ACA,MCA,PCA) with perfusion Time-to-peak (TTP) maps. Patient-specific blood flow simulations using physiology-informed boundary conditions calculated stenotic pressure ratios for both the patient’s acute and a population-based healthy scenario. The changes in affected territory volumes and pressure ratio between healthy and acute conditions and the acute TTP delays were presented to an expert reader who stratified cases into three clinical groups (A) non-hemodynamic, (B) hemodynamically hazardous with insufficient collateral support and (C) hemodynamically stable due to collateralisation. These results were compared against patient outcomes of recurrent ischemic events attributed to the target stenosis using the commonly used 70% threshold. Results: (95%CI in brackets) Patients (n=47, age: 73±11Y, 23F/24M) were stratified across the three categories A) 30, B) 15, C) 2. Of the patient groups with follow-up (n=31), categorisation of hemodynamic ICAD against recurrent ipsilateral stroke in territory (n=8) yielded a sensitivity of 75% [34-97] and specificity of 91% [72-98]. Mean±standard deviation of stenosis degree (SD) 55±14% for patients across each cohort was A) 50±11%, B) 70±9%, C) 70%. This is compared to using 70% stenosis threshold for dichotomising patients against risk of recurrent stroke, which yielded a sensitivity of 62.5% [24-91], and specificity of 87% [66-97]. Conclusions: We report on a CTP derived method for stratifying hemodynamically significant ICAD. The methodology has potential in both in assessing symptomatic chronic ICAD and identifying cohorts who would benefit from endovascular intervention.