Color Doppler sonography of benign and malignant pulmonary masses

The purpose of this study was to compare blood flow in benign and malignant pulmonary masses by assessing the spectral waveforms obtained during color Doppler sonography.

Fifty lung cancers in 46 patients and 28 benign lung lesions in 28 patients were evaluated with color Doppler sonography. Spectral wave analysis of blood flow (specifically, the Doppler variables of pulsatility index, resistive index, peak systolic velocity, and end diastolic velocity) was used to determine the distal impedance of vessels in malignant and benign pulmonary lesions.

The flow signal detection rates for lung cancers and benign pulmonary lesions were 64% and 79%, respectively. All lung cancers with detectable flow signals had either relatively low-impedance flows or arteriovenous shunting, unlike the benign lesions, which usually had relatively high-impedance flows. For lung cancers, the pulsatility index was 1.43 +/- 0.31, the resistive index was 0.52 +/- 0.13, peak systolic velocity was 0.17 +/- 0.07 m/sec, and end diastolic velocity was 0.07 +/- 0.03 m/sec. For benign lung lesions, the pulsatility index was 3.32 +/- 0.68, the resistive index was 0.90 +/- 0.06, peak systolic velocity was 0.28 +/- 0.09 m/sec, and end diastolic velocity was 0.03 +/- 0.01 m/sec. All four variables were significantly different (p < .001) between lung cancers and benign lung lesions. When a cutoff value of mean +/- 2 SD was used, the resistive index and pulsatility index were shown to be sensitive and specific for the diagnosis of lung cancer (sensitivity, specificity = 100%, 95% for resistive index; 97%, 95% for pulsatility index). Flow was detected less often in squamous cell carcinoma than in adenocarcinoma and small-cell carcinoma.

We conclude that color Doppler sonography is useful for showing vascularity in pulmonary masses, and may be helpful in differentiating malignant from benign lung tumors.