High Resolution Ultrasound Speeds Up Prostate Cancer Diagnosis

Each year, approximately one million prostate cancer biopsies are conducted across Europe, with similar numbers in the USA and around 100,000 in Canada. Most of these biopsies are performed using MRI images combined with conventional ultrasound, allowing urologists to directly target potential tumors for more accurate diagnoses. However, the process of MRI-guided biopsy involves two steps: first, an MRI scan, followed by an ultrasound-guided biopsy. This procedure requires multiple hospital visits and specialist radiological expertise to interpret the MRI images and align them with the ultrasound. Now, an international clinical trial has demonstrated that biopsies guided by high-resolution ultrasound are just as effective as those using MRI for diagnosing prostate cancer.

Known as micro-ultrasound, this technology is less expensive and easier to use compared to MRI. It could greatly accelerate diagnosis, reduce the need for multiple hospital visits, and free up MRI resources for other purposes, as per the findings of the trial led by researchers at the University of Toronto (Toronto, ON, Canada). Micro-ultrasound operates at a higher frequency than traditional ultrasound, providing three times the resolution, which captures detail comparable to MRI scans for targeted biopsies. Urologists and oncologists can quickly learn to use the technique and interpret the images, especially if they are already experienced with conventional ultrasound. Micro-ultrasound is not only cheaper to acquire and operate than MRI, but it could also allow imaging and biopsies to be completed in a single appointment, even in non-hospital settings.

The OPTIMUM trial is the first randomized study to compare micro-ultrasound (microUS)-guided biopsy with MRI-guided biopsy for prostate cancer detection. The trial involved 677 men who underwent biopsies at 19 hospitals across Canada, the USA, and Europe. Half of the participants had MRI-guided biopsies, a third received both microUS-guided biopsy followed by MRI-guided biopsy, and the remaining patients only had the microUS-guided biopsy. The results of the OPTIMUM trial were presented at the European Association of Urology Congress in Madrid and published in JAMA. The microUS technique was found to be as effective as MRI-guided biopsy, with nearly identical detection rates across all three groups. Even in the group that received both types of biopsies, microUS identified the majority of significant cancers. According to the researchers, the results of the OPTIMUM trial could have a similar transformative impact as the initial introduction of MRI technology.

“When MRI first emerged and you could image prostate cancer accurately for the first time to do targeted biopsies, that was a gamechanger. But MRI isn’t perfect. It’s expensive. It can be challenging to get access to it quickly. It requires a lot of experience to interpret properly. And it uses gadolinium which has some toxicity. Not all patients can have MRI, if they have replacement hips or pacemakers for example,” said Laurence Klotz, Professor of Surgery at the University of Toronto’s Temerty Faculty of Medicine and the Sunnybrook Chair of Prostate Cancer Research. “But we now know that microUS can give as good a diagnostic accuracy as MRI and that is also game changing. It means you can offer a one stop shop, where patients are scanned, then biopsied immediately if required. There’s no toxicity. There are no exclusions. It’s much cheaper and more accessible. And it frees up MRIs for hips and knees and all the other things they’re needed for.”

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