Focus of the Report: In its application to prostate biopsy, micro-ultrasound (mUS), also known as high-resolution ultrasound (US), not only provides guidance for the biopsy needle but also allows identification of features that cannot be revealed by conventional US. Thus, mUS has the potential to identify cancerous lesions that might otherwise remain undetected.

Technology Description: mUS is characterized by a frequency of 29 megahertz (MHz), which results in 3 times the resolution of conventional US (9-12 MHz). A 2014 pilot study of images and biopsy samples from 25 men with known prostate cancer suggested that mUS was more sensitive and more specific than conventional US for detecting small suspicious lesions.

Controversy: Conventional US is the standard technology used to guide the biopsy needle during prostate biopsy. The US images can be used to identify suspicious sites from which biopsy cores might be taken, but hypoechogenicity, the feature that can be identified using conventional US, is a poor predictor of cancer. National and international guidelines suggest consideration of multiparametric magnetic resonance imaging (mpMRI) if clinical suspicion of prostate cancer remains despite negative biopsy results. However, magnetic resonance imaging (MRI)-targeted biopsy misses up to 23% of clinically significant lesions. Other drawbacks to MRI involve higher cost, need for additional radiologist expertise to interpret mpMRI, steep learning for mastery of fusion technology, patient inconvenience due to need for 2 or more visits, and lack of MRI access in some communities. The goal of mUS is to improve the diagnostic accuracy of prostate biopsy while maintaining the affordability and convenience of US.

Key Questions:

  • Is prostate biopsy guided by mUS accurate in identifying cancerous lesions (clinical validity)?

  • Does the use of mUS in prostate biopsy change treatment decisions or improve health outcomes (clinical utility)?

  • How does mUS compare with other imaging technologies that can be used for targeted prostate biopsy?

  • Is mUS for prostate biopsy safe?

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