# Comparison of Duplex Ultrasound and Digital Subtraction Angiography for Assessing Tibial Vessel Disease

## TL;DR

This study compares duplex ultrasound and digital subtraction angiography for diagnosing tibial artery disease and finds ultrasound significantly underestimates severity.

## Contribution

Demonstrates limitations of duplex ultrasound as a diagnostic tool for tibial vessel disease in patients with critical limb ischemia.

## Key findings

- Duplex ultrasound showed poor agreement with digital subtraction angiography (Kappa=0.19)
- Ultrasound underestimated vessel pathologies with 23% sensitivity and 41% negative predictive value
- Study recommends caution in using ultrasound for diagnosing tibial disease in critical limb ischemia patients

## Abstract

Background

Duplex ultrasonography (DUS) is readily available and often used as the first diagnostic test for patients with peripheral artery diseases (PADs). PAD is a disease that affects the general population but more commonly affects diabetics. To date, the role of DUS in the assessment of tibial vessel disease is inconclusive at best. The goal of our study is to assess the validity of DUS in characterizing the presence and severity of tibial diseases via comparison with digital subtraction angiography (DSA) findings.

Methods

This is a single-center retrospective cohort study analyzing three arterial segments (anterior tibial, posterior tibial, and fibular arteries) in patients who received a duplex study followed by DSA within a 30-day period. All arterial segments were graded from normal (Grade 0) to occluded (Grade 4), based on duplex interpretation and directly compared to direct visualization findings from DSA. Using statistical methods, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of DUS were determined.

Results

A total of 171 tibial vessel segments from 57 enrolled subjects with critical limb ischemia symptoms were analyzed in this study. The agreement between both modalities was poor (Kappa=0.19, p < 0.05), with DUS demonstrating a significant underestimation of vessel pathologies. This is also reflected by the overall sub-optimal sensitivity (23%), specificity (84%), PPV (69%), and NPV (41%) in DUS when compared to DSA results as the gold standard.

Conclusion

Significant disagreements were noted in this study between DUS and DSA findings, primarily significant underestimation of tibial vessel disease by the DUS when compared with the DSA. Caution is advised in the clinical application of DUS in patients with chronic limb-threatening ischemia (CLTI) symptoms and multi-segment tibial vessels due to its demonstrated limitations in this study.