The role of colour flow Doppler in the investigation of the salivary gland tumour.

Aims: Ultrasound is a highly effective imaging technique to determine salivary gland tumours and may help to identify many benign lesions. The aim of this study is to evaluate whether colour Doppler is able to further differentiate the malignant tumour.

Methods: Fifty-six patients with salivary gland lesions were prospectively assessed using ultrasound imaging with colour flow and power Doppler. The peak systolic velocity (PSV) was measured and the pulsatility index (PI) and resistive index (RI) calculations were performed on the pulsed wave traces. The real time ultrasound morphology and the Doppler information were correlated with the histology.

Results: In 18 of the 56 patients, no internal colour flow or power Doppler changes could be detected. The real time ultrasound morphology diagnosed benign disease with sensitivity of 89.7% with specificity of 57.1%. The positive predictive value was 93.6%. There were no significant differences in the colour Doppler appearances in terms of vessel type or intratumour distribution which could separate benign from malignant conditions. However, there was statistical discrimination for PI and RI values (P = 0.0006, P = 0.0002, respectively). No malignant lesions were seen when the PI was less than 1.8 and RI was less than 0.8. The PSV was elevated in several cases (> 50 cm per s) but there was no statistical correlation with malignancy.

Conclusion: The risk of malignancy increases by a third when the colour Doppler demonstrates increased intratumour vascular resistance (RI > 0.8 and PI > 1.8), with positive predictive value of 97.3% (sensitivity 75.5%, specificity 85.7%).Bradley, M. J. (2000). Clinical Radiology55, 759-762.