Diagnostic performance of Angio-Based fractional flow for hemodynamic assessment in intracranial Atherosclerosis.

OBJECTIVES

To evaluate the diagnostic performance of Angio-based fractional flow (Angio-FF), a computational fluid dynamics technique, for identifying hemodynamically significant intracranial atherosclerotic stenosis (ICAS) compared with the degree of stenosis (DS).

MATERIALS AND

METHODS

This retrospective study included 348 patients with unilateral ICAS. Angio-FF was calculated using AccuFFicas V1.0 software. Diagnostic accuracy, sensitivity, specificity, and area under the ROC curve (AUC) were compared between Angio-FF and DS, stratified by stenosis severity, vascular territory, and Angio-FF gray zone.

RESULTS

Symptomatic lesions exhibited lower Angio-FF (median 0.46 vs. 0.83,P < 0.001) and higher DS (69.5 % vs. 62.5 %,P < 0.001). Angio-FF showed superior AUC (0.884 vs. 0.664,P < 0.001) than DS. Angio-FF, using a cutoff value of 0.69, demonstrated significantly higher sensitivity (81.4 % vs. 50.0 %), specificity (88.9 % vs. 68.9 %), accuracy (83.3 % vs. 54.9 %), positive predictive value (PPV) (95.5 % vs. 82.2 %), and negative predictive value (NPV) (62.5 % vs. 32.5 %) compared to DS (≥ 70 % stenosis) for identifying culprit lesions (P < 0.001). Diagnostic performance was significantly better in anterior circulation lesions than in posterior ones, with higher sensitivity (91.8 % vs. 60.9 %), accuracy (89.5 % vs. 73.1 %), and NPV (73.1 % vs. 55.3 %) (all P < 0.05), while specificity and PPV remained high in both regions. Within the Angio-FF gray zone (0.64-0.74), diagnostic performance was lower than outside the zone, with reduced sensitivity (67.4 % vs. 84.4 %), accuracy (72.4 % vs. 85.5 %), and NPV (42.3 % vs. 67.6 %) (all P < 0.05), yet it still outperformed DS, with a higher AUC (0.795 vs. 0.524, P = 0.003).

CONCLUSIONS

Angio-FF outperformed conventional DS assessment in identifying hemodynamically significant ICAS, with particularly high accuracy in lesions with < 70 % stenosis. Despite reduced performance within the gray zone, it remained more reliable than DS.

ABBREVIATIONS: ICAS, intracranial atherosclerotic stenosis; TIA, transient ischemic attack; DS, degree of stenosis; FF, fractional flow; Angio-FF, Angio-based fractional flow; CFD, computational fluid dynamics; DSA, digital subtraction angiography; AUC, area under the curve; ROC, receiver operating characteristic; PPV, positive predictive value; NPV, negative predictive value; DCA, decision curve analysis; MCA, middle cerebral artery; BA, basilar artery; VA, vertebral artery; IQR, interquartile range; MRA, magnetic resonance angiography; Pa, proximal arterial pressure; Pd, distal arterial pressure; TIMI, Thrombolysis In Myocardial Infarction.