Detection of arterial dilatation in the distal aorta--lower limb arteries using continuous wave Doppler ultrasound

Continuous wave Doppler ultrasound techniques were used to obtain signals from the common femoral, popliteal, posterior tibial and dorsalis pedis arterial sites and the ankle systolic pressure indices in 54 patients with arteriographic, ultrasound "B"-Scan or surgical confirmation of arterial dilatation. The Doppler-shifted signals were spectrum-analysed and processed using a maximum frequency detector. The maximum frequency envelopes were examined retrospectively to determine whether there were any characteristics of the signals which could be used as diagnostic indicators of arterial dilatation. Ankle systolic pressure indices (ASPI), pulsatility index (PI), and delta, derived from the Laplacian transform method, were used in an attempt to quantify any changes produced by dilatation. The results indicate that characteristic and distinctive maximum frequency envelope signatures can be identified with arterial dilatation but that parameters such as ASPI and PI cannot distinguish these changes from the normal state and the Laplacian transform parameter "delta" places the dilatation cases in the minor stenosis category. However, generalised dilatation can be detected with a sensitivity of 85% if pattern recognition techniques are used.