MRI/Ultrasound Fusion Prostate Biopsy: New Option for Diagnosis
When concern arises that a man may have prostate cancer, the current recommendation is to perform an ultrasound (US) guided biopsy. Using sound waves, we are able to visualize the prostate for sampling of various areas of the gland. However, since we are not able to visualize areas concerning for cancer particularly well with ultrasound, we may be falsely reassured with a biopsy showing a less aggressive cancer (or no cancer at all).
Identifying Significant Cancers
With the emergence of personalized medicine in the treatment of prostate cancer, we are able to improve outcomes and quality of life when armed with all of the necessary information. As such, it is crucial to identify cancers that require treatment while avoiding the risk of treating cancers that are lower risk.
For the last 10-15 years, magnetic resonance imaging (MRI) of the prostate has proven to be a reliable, non-invasive imaging tool for the detection and assessment of prostate cancer. As a result, clinicians and researchers have been working to develop biopsy methods that utilize MRI in order to improve the accuracy of these tests. One such strategy is to combine the superior visualization of potential cancers by MRI with the technical and cost advantages of US-guided biopsy.
Combining MRI and Ultrasound Images During Biopsy
Recent studies (references below) show that using MRI images to target significant cancers during the US-guided biopsy significantly improves the detection of clinically relevant cancers. This combination of overlaying MRI images with the US images during the biopsy is known as MR/US fusion biopsy (as it is a “fusion” of MRI and US imaging). The combined image allows the suspicious areas identified in the MRI to be targeted during US-guided biopsy. As such, the physician performing the test will have a better sense of where biopsy should be taken, rather than randomly sampling from the whole prostate.
Improved Detection
In men with suspected prostate cancer undergoing their first prostate biopsy, MR/US fusion biopsies significantly increase the detection of high-risk aggressive prostate cancer (by 12-30 percent) while reducing the detection of low-risk prostate cancer compared with standard biopsy by 13 percent. This difference is seen even more clearly in patients who have had multiple negative biopsies, where MR/US fusion biopsy has been shown to have 1.4 times the detection rate of significant cancers compared to standard US-guided biopsy, reducing any further delay in treatment.
In summary, the MR/US fusion biopsy allows for increased (and earlier) detection of clinically significant cancer, which helps to optimize treatment decisions for the individual patient and brings us one step closer to providing precision medicine for our prostate cancer patients.
- Kasivisvanathan V, Rannikko AS, Borghi M, et al. MRI-Targeted or Standard Biopsy for Prostate-Cancer Diagnosis. N Engl J Med. 2018;378(19):1767-1777. doi:10.1056/NEJMoa1801993
- Siddiqui MM, Rais-Bahrami S, Turkbey B, et al. Comparison of MR/ultrasound fusion-guided biopsy with ultrasound-guided biopsy for the diagnosis of prostate cancer. JAMA. 2015;313(4):390-397. doi:10.1001/jama.2014.17942
- Costa DN, Bloch BN, Yao DF, et al. Diagnosis of relevant prostate cancer using supplementary cores from magnetic resonance imaging-prompted areas following multiple failed biopsies. Magn Reson Imaging. 2013;31(6):947-952. doi:10.1016/j.mri.2013.02.007