POWER-BASED COLOR-CODED DUPLEX SONOGRAPHY FOR EVALUATION OF CALF VEINS

Background. Power-based colour coded duplex sonography (PD) has been d escribed to display lower flow velocities compared to frequency-based colour coded duplex sonography (CD). This study was undertaken to stud y the clinical usefulness of PD in the evaluation of calf veins in sus pected deep vein thrombosis. Methods. Experimental design: A prospecti ve, comparative study. Setting: University hospital, Switzerland. Pati ents and Measures: CD of the complete deep venous system and complemen tary PD of paired calf veins were performed in 50 consecutive patients with clinically suspected DVT. All except three patients, with failed vein puncture at the dorsum of the foot, had a venography used as ref erence test for confirmatory diagnosis of DVT. Results. Complete ident ification of calf veins increased from 80.5% using CD to 97.9% using c omplementary PD (p=0.007). Overall accuracy to detect an acute calf DV T was 96% (95% CI, 85-99%) and 95% (95% CI, 83-99%), respectively. Acc uracy was 95% (95% CI, 83-99%) using CD vs 94% (95% CI, 82-98%) using PD in posterior tibial, 87% (95% CI, 74-95%) vs 85% (95% CI, 71-94%) i n anterior tibial, and 95% (95% CI, 83-99%) vs 96% (95% CI, 85-99%) in peroneal veins. Chronic postthrombotic changes (10.6%) were more reli ably recognized using CD (accuracy 83% [95% CI, 72-94%]) compared to P D (accuracy 66% [95% CI, 59-85%]) due to tissue motion artifacts and i nability to discriminate the direction of blood flow. Conclusions. PD used complementary with CD is capable of significantly improving ident ification of paired calf veins without loss of diagnostic accuracy in the diagnosis of acute DVT.