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%). Advances in knowledge: Different prostatic lesions are mostly similar in grayscale ultrasound. Imaging plays an important role in differentiation of prostatic nodules. Ultrasound elastography may play an important role in distinguishing benign from malignant nodules.