Evaluating the Role of Ultrasound in Prostate Cancer trial - phase 1: Early experience of micro-ultrasound in the United Kingdom

Abstract

Purpose: The purpose of this study was to evaluate if the use of micro-ultrasound can detect clinically significant prostate pathology when compared to histology obtained during a transperineal prostate biopsy.

Methods: Patients suspected of having prostate cancer, who had a pre-biopsy magnetic resonance imaging and could tolerate a transrectal examination, were prospectively recruited. All patients had a micro-ultrasound scan prior to their biopsy. The findings of magnetic resonance imaging, micro-ultrasound and histology were risk stratified in accordance with local pathways. Comparison of assigned risk scores was made using histology as the reference standard.

Results: Data from 101 patients were evaluated. Histology showed that clinically significant prostate cancer was detected in 48.5% (n = 49/101) of patients. Moderate inter-rater agreement was found in both magnetic resonance imaging and micro-ultrasound with К of 0.31 in both modalities. High-risk findings were identified in 81% (n = 82/101) patients at magnetic resonance imaging and in 66% (n = 67/101) patients at micro-ultrasound. Sensitivity and specificity of magnetic resonance imaging were found to be 87% and 34.6% and for micro-ultrasound 73.3% and 53.8%, respectively.

Conclusion: A limitation of this study was that the biopsy was not performed with micro-ultrasound which may have resulted in unidentified cancers and lowered the apparent accuracy of the technique. However, we conclude that while micro-ultrasound was diagnostic, magnetic resonance imaging demonstrated higher sensitivity in our local population and remains the pre-biopsy imaging modality of choice. However, the higher specificity of micro-ultrasound identified does indicate that it may be of value when magnetic resonance imaging is contraindicated. The role of micro-ultrasound, within an active surveillance pathway for prostate cancer, warrants further investigation.

Keywords: Sonographer; active surveillance; diagnosis; micro-ultrasound; prostate biopsy.

Image 1.

MicroUS image of high-risk prostate – region of interest marked (LS section).

Image 2.

T2 MRI of high-risk prostate – region of interest marked (axial plane).

Image 3.

MicroUS image of low-risk prostate demonstrating ductal patches throughout (LS section).

Image 4.

T2 MRI of low-risk prostate demonstrating normal peripheral and transition zones (axial plane).

Image 5.

Distribution of histological outcomes post prostate biopsy.