Doppler perfusion index: An interobserver and intraobserver reproducibility study

PURPOSE: To assess the potential of Doppler perfusion index (DPI) measurement as a routine diagnostic tool in the detection of occult colorectal liver metastases. MATERIALS AND METHODS: By using color Doppler ultrasound, two independent sonologists performed DPI measurements blindly in 20 patients aged 30-82 years; interobserver reproducibility was assessed. A second group of 20 patients aged 37-88 years were examined to assess the level of intraobserver reproducibility of DPI measurements attained by one sonologist. For each patient in this group, the DPI was measured three times in succession, and the variability between measurements was analyzed. Calculations of the intraclass correlation coefficient and the coefficient of variation (CV) were used to determine the levels of reproducibility. The data were also analyzed by using the Student paired t test, with significance established at P less than .05. RESULTS: The interobserver CV and intraobserver CV were 20% and 16%, respectively. The two sonologists who examined the first group of patients agreed independently on the DPI status in 18 of 20 (90%) patients. CONCLUSION: In this study, both the intraobserver reproducibility and the interobserver reproducibility of DPA measurements were clinically acceptable.