Objective To assess the adjunctive diagnostic value of intra-arterial cone-beam CT angiography (IA-CBCTA) relative to digital subtraction angiography (DSA) in the anatomic identification/localization of intracranial/spinal arteriovenous fistulas (AVFs) and utility for surgical/endovascular treatment planning.

Methods Retrospectively, two blinded observers scored DSA and IA-CBCTA images of 32 patients with intracranial/spinal AVFs based on a qualitative scale. The following parameters were scored: arterial feeders, venous drainers and course, fistula site, and adjacent anatomic landmarks for cross-sectional localization. The total score was defined as the overall diagnostic value. Differences between IA-CBCTA and DSA scores were defined as the IA-CBCTA efficacy value. Observers described the treatment strategy at the end of DSA and IA-CBCTA grading, respectively. Mann–Whitney U test, Wilcoxon's signed rank test, and Kendall’s tau (τ) coefficient were used for statistical analysis.

Results Interobserver agreement of overall diagnostic value for IA-CBCTA was good (τ=0.59, p=0.001) with no significant variance between the two observers' IA-CBCTA efficacy values (p=0.2). Significantly higher scores were assigned to IA-CBCTA for overall diagnostic value (both observers: p<0.0001), delineation of fistula site (observer 1: p<0.0001, observer 2: p=0.0003), and adjacent anatomic landmarks (both observers: p<0.0001). Observers found IA-CBCTA helpful, enabling a more confident treatment approach in 30 and 29 cases for observer 1 and observer 2, respectively. Both observers altered the treatment plan in two cases based on IA-CBCTA findings.

Conclusions IA-CBCTA as an adjunctive technique to DSA improves the anatomic delineation of AVFs, particularly for the fistula site and cross-sectional localization, and has the potential to improve treatment planning.