High-resolution transrectal ultrasound: pilot study of a novel technique for imaging clinically localized prostate cancer

Abstract

Objectives: To determine how high-resolution transrectal ultrasound (HiTRUS) compares with conventional TRUS (LoTRUS) for the visualization of prostate cancer.

Methods and materials: Twenty-five men with known prostate cancer scheduled for radical prostatectomy were preoperatively imaged with both LoTRUS (5MHz) and HiTRUS (21MHz). Dynamic cine loops and still images for each modality were saved and subjected to blinded review by a radiologist looking for hypoechoic foci ≥ 5 mm in each sextant of the prostate. Following prostatectomy, areas of prostate cancer ≥ 5 mm on pathologic review were anatomically correlated to LoTRUS and HiTRUS findings. The accuracy of LoTRUS and HiTRUS to visualize prostate cancer in each sextant of the prostate and to identify high-grade and locally advanced disease was assessed. The McNemar test was used to compare sensitivity and specificity and paired dichotomous outcomes between imaging modalities.

Results: Among 69 sextants with pathologically identified cancerous foci at radical prostatecomy, HiTRUS visualized 45 and missed 24, whereas LoTRUS visualized 26 and missed 43. Compared with LoTRUS, HiTRUS demonstrated improved sensitivity (65.2% vs. 37.7%) and specificity (71.6% vs. 65.4%). HiTRUS's agreement with pathologic findings was twice as high as LoTRUS (P = 0.006). HiTRUS provided a nonsignificant increase in visualization of high-grade lesions (84% vs. 60%, P = 0.11).

Conclusions: HiTRUS appears promising for prostate cancer imaging. Our initial experience suggests superiority to LoTRUS for the visualization of cancerous foci, and supports proceeding with a clinical trial in the biopsy setting.

Keywords: Diagnosis; Prostate cancer; Radical prostatectomy; Sensitivity and specificity; Ultrasound.