Abstract 3014: Accuracy of Duplex Ultrasound Examination for Detecting Below Knee Artery Lesions
Background: Advances of interventional techniques and development of new devices allow us to revascularize lesions of below the knee arteries (BKA) in patients with peripheral arterial disease (PAD). Although Duplex ultrasound (US) is well established to evaluate the location, length, and severity of aortoiliac and femoropopliteal lesions, its accuracy for detecting BKA lesions has not been studied.
Objective: To determine the diagnostic accuracy of Duplex US for BKA lesions by comparing with MSCT angiography.
Methods: Sixty-seven patients (69±11 years, 54 males) with PAD were included in this study. Duplex US was performed in 229 BKA by using Aloka α10 or Toshiba Aplio XV. Anterior and posterior tibial arteries were scanned by using a 7.5-MHz linear transducer. When compared with popliteal arteries, changes in Doppler flow signal patterns (Flow pattern method), decrease in peak flow velocities (>0.02 m/sec) (Peak flow method), and/or increase in acceleration time (>5 msec) (ACCT method), were considered as positive for the presence of significant BKA stenosis. By comparing with the angiographic findings obtained by MSCT, sensitivity, specificity, positive predictive value, and negative predictive value of US in detecting BKA stenosis were determined.
Results: MSCT showed significant stenoses in 115 of 229 BKA (50.2%). MSCT also revealed that 151 BKA (68.1%) were associated with significant stenosis above the knee level. Doppler findings were compared with the results of MSCT findings, and are summarized in the Table⇓.
Conclusions: Although positive predictive value of Doppler parameters in detecting BKA lesions was within acceptable range, negative predictive value was relatively low. Duplex US is thus not optimal as a screening test for BKA lesions. Color flow Doppler scanning of entire BKA may be required to further improve the accuracy of detecting BKA lesions as well as to determine the treatment strategies including percutaneous peripheral intervention.