Ultrasound elastography in characterization of prostatic lesions: Correlation with histopathological findings

Abstract

Objective: Ultrasound elastography is increasingly used in the diagnosis of prostate cancer, however results are heterogeneous. We correlate in a large sample-size prospective study the accuracy of elastography, aiming to settle an accurate cut-off point for diagnosis and possibility of use as a screening tool. Methods: Prospective study that included 120 patients with mean age 59.5 } 9.8 years, showing enlarged prostate by clinical examination with prostate-specific antigen >4 ng ml-1. The study was done using high frequency high resolution endorectal probe with real time tissue elastography. Grayscale ultrasound examination was done first with Doppler followed by elastography color-coded map and strain ratio measurement. Then, transrectal ultrasound-guided core biopsy was done from suspicious areas detected by elastography (totally or partly stiff by color-coded map or with relative increased strain ratio), besides standard six-quadrant core biopsy samples. Results: There was statistically significant difference (p < 0.001) regarding strain ratio in benign and malignant lesions. Strain ratio showed significant proportionate correlation with prostate-specific antigen level and Gleason pathological score, while no significant correlation noted with the age or the prostatic volume. A strain ratio with a cut-off value of 1.9 showed a sensitivity of 100%, specificity 93.8%, positive predictive value of 79.3%, negative predictive value 100 and 95% accuracy in differentiating between malignant and benign lesions. Conclusion: Strain ratio improves the detection of prostatic cancer with high sensitivity (100%) and high negative predictive value (100%).