Background: Conventional angiography remains the standard diagnostic modality for arteriovenous (AV) access dysfunction in hemodialysis patients, but its geometric accuracy is limited. Intravascular ultrasound (IVUS) offers superior lesion detection, yet its absolute measurement accuracy remains uncertain. Using three-dimensional (3D) printed vascular conduits as reference standards, we assessed the accuracy of IVUS versus angiography, hypothesizing that complex conduit geometry, quantified by Gaussian curvature, would exacerbate angiographic error. Methods Clinically relevant AV access geometries were modeled with computer-aided design (CAD) and fabricated using 3D printing. Lumen diameters were measured by contrast angiography and IVUS and compared with CAD dimensions. Conduit geometry was characterized using finite element–based Gaussian curvature mapping. Paired Student’s t-test, Tukey-Kramer correction for multiple testing, and linear mixed-effect modeling were performed to examine the influence of clustering of lesions within conduits. Results: IVUS demonstrated significantly lower measurement error compared with angiography, especially in stenotic segments with >50% luminal narrowing, which persisted even after correction for multiple comparisons (P < 0.05). These high-grade stenoses frequently coincided with regions of especially high positive or negative Gaussian curvature, reflecting complex conduit geometry. In such regions, angiography consistently underestimated lumen diameter, with error magnitude increasing in curved or tortuous lesions. IVUS measurements closely approximated CAD measurements, retaining accuracy even in severe stenoses. For mild stenoses (< 50%) and aneurysmal dilatations, both modalities performed comparably. Conclusions: Geometric complexity directly contributes to modality-specific error. Angiography systematically underestimates lumen dimensions in complex, stenotic regions, while IVUS detects them with higher fidelity and preserves accuracy. These findings establish IVUS as the more reliable modality for evaluating AV access dysfunction and support its integration into routine practice in guiding intervention for AV access stenosis.
Decker et al. (Fri,) studied this question.