Evaluation of Arterial Stenosis in Head and Neck CTA Using a Novel Virtual Non-Calcium Reconstruction Algorithm with Photon-Counting CT

Purpose This study aimed to evaluate the diagnostic performance of the virtual non-calcium reconstruction algorithm (VNCa) on photon-counting detector computed tomography (PCD-CT) for assessing head and neck arterial stenosis and to compare it with that of traditional threshold three-dimensional (T3D) reconstructions. Materials and Methods In this retrospective single-center study, patients who underwent both PCD-CT angiography (CTA) and digital subtraction angiography (DSA) between April 10, 2024, and March 1, 2025, were enrolled. The diagnostic performance of VNCa and T3D images for assessing head and neck arterial stenosis was compared using DSA as the reference standard. Results Thirty-one patients with 76 stenoses were included. The mean age was 65.19 ± 13.55 years, with a predominance of males (18/31, 58.1%). VNCa images exhibited better agreement with DSA than T3D, showing smaller errors at both the vessel (1.59% vs. 8.17%) and patient (1.87% vs. 6.90%) levels. Confusion matrices at both the vessel and patient levels indicated that VNCa images achieved higher four-category agreement with DSA than T3D, with fewer upward misclassifications, particularly in mild stenosis. For identifying stenosis ≥ 50%, VNCa images achieved an area under the curve (AUC) of 0.993, with 96.4% sensitivity, 95.8% specificity, and 96.1% accuracy; corresponding values for T3D were 0.953, 96.4%, 72.9%, and 81.6%, respectively (p = 0.001). At the patient level, the AUCs were 0.993 for VNCa images and 0.945 for T3D (p = 0.239). VNCa images consistently yielded smaller signed errors across all plaque types, with the largest improvement observed in calcified plaques. Conclusion PCD-CT with VNCa imaging improves the accuracy of stenosis assessment compared with conventional T3D reconstruction, offering more reliable classification of disease severity and potential benefits for patient management in head and neck atherosclerotic disease.