The Utility of Transrectal Real-Time Elastography in the Diagnosis of Prostate Cancer

Abstract 

The aim of this study is to evaluate the diagnostic performance of transrectal real-time elastography (TRTE) to differentiate benign from malignant prostatic lesions, with pathologic diagnosis obtained by prostatic needle biopsy. Conventional gray scale transrectal ultrasonography (TRUS) and power Doppler ultrasonography (PDUS) were performed in 107 men who had elevated serum prostate-specific antigen level >4 ng/mL or abnormal findings on digital rectal examination. For baseline TRUS and PDUS imaging, the suspicion of carcinoma was scored using previously proposed five-point subjective scale. For TRTE imaging, we used newly adopted five-point subjective scale based on the degree and distribution of strain in relation to hypoechoic area, which simultaneously displayed on B-mode image. All patients underwent transperineal systematic 8-cores biopsies, as well as up to four cores of targeted biopsy from suspicious area by TRUS, PDUS and/or TRTE. The samples were diagnosed pathologically and compared with the findings of TRUS, PDUS and TRTE. Prostate cancer was detected in 40 (37%) of 107 patients. When a cutoff point of 3 (displaying focal asymmetric lesion without strain not related to hypoechoic lesion) was used, TRTE had 68% sensitivity, 81% specificity and 76% accuracy. TRTE was comparable with PDUS (70% sensitivity, 75% specificity and 73% accuracy) and had significantly higher sensitivity than TRUS (68% vs. 50%, p = 0.027). Combination of TRTE with PDUS increased sensitivity to 78%. The detection rate of directed biopsy from suspicious area in either TRTE or PDUS (TRTE+PDUS–directed biopsy) was 29% (31/107) by patient and was comparable with systematic biopsy (31%, 33/107, p = 0.86), whereas the detection rate of TRTE+PDUS–directed biopsy by core (55/111, 50%) was significantly higher than systematic biopsy (132/856, 15%, p < 0.0001). For assessing prostatic lesions, TRTE with B-mode image-based scoring had almost the same diagnostic performance as PDUS. Although TRTE+PDUS–directed biopsy detected comparable number of cancers with systematic biopsy, both techniques should be used supplementarily for minimizing the number of missing cancers. (E-mail: kamoi@koto.kpu-m.ac.jp)

Key Words: Ultrasound, Power Doppler, Elastography, Prostatic neoplasms