This was a study designed to compare the accuracy of high-resolution micro-ultrasound, which is a fairly new technology, to MRI with conventional ultrasound and fusion-targeted biopsy. So micro-ultrasound is different from conventional ultrasound in that it is high frequency, 29MHz compared to about 7 or 9 MHz with conventional ultrasound, and that means the resolution is about three times higher, 70μm rather than 200μm.  70μm is the diameter of a prostatic duct and it means that alterations in ductal anatomy that occur with cancer that result in restricted diffusion on MRI also produces a signal that’s detectable on micro-ultrasound. So you are able to see cancers with micro-ultrasound very similar to the way you see them with MRI.

The technology has been widely available for four or five years now and there are about 75 studies in the literature that are mostly registration or single-centre studies that suggest that the sensitivity and specificity is comparable to MRI. But this was an attempt to get high-quality level 1 evidence from a large prospective international randomised trial comparing the sensitivity and the performance to MRI.

So the study accrued 802 patients, it was a three-arm study. Micro-ultrasound with systematic and targeted biopsy. Every patient got systematic and targeted biopsy if there was a target. So micro-ultrasound, MRI with conventional fusion targeting, and arm 3 was the combination of MRI with micro-ultrasound and targeted biopsy. In that arm the biopsy was done blinded to the MRI then unblind the MRI and then additional targeted biopsies if necessary.

To make a long story short, the trial certainly succeeded well in terms of accrual, it accrued quite rapidly. It was done in 20 centres, 8 countries, and it was a non-inferiority design. The results were that micro-ultrasound performed very comparable to MRI in terms of the diagnosis of grade group 2 or higher and grade group 3 or higher prostate cancer. In fact, there was a 4.5% higher grade group 2 or greater cancer diagnosis rate with the micro-ultrasound alone compared to the MRI. In the combined group, MRI plus micro-ultrasound, there was some small incremental benefit of using the combined approach but not very much, just a few percent.

So that’s basically the results in a nutshell. If we looked only at the targeted biopsy diagnosis rate, leaving out the systematic biopsy, the results were exactly the same, no difference. So non-inferiority was demonstrated with a p-value of about 0.0009, it was a very high degree of confidence that one could confirm non-inferiority.

We think that’s quite a significant finding. Micro-ultrasound has a lot of advantages, practical advantages, over MRI. First of all, in many parts of the world MRI is not widely accessible, there’s restricted access. So for those parts of the world, and I include Canada where I’m from in that category, where patients often have to wait a long time to get an MRI, with micro-ultrasound there’s no need for that. There is no requirement for contrast and it’s one-stop shopping. So the patient comes, imaging with micro-ultrasound and local anaesthesia and biopsy all at the same time. So that’s very appealing to patients, they don’t have to have the MRI in the co-registration then come back.  So we think this is potentially quite practice changing.

Is there anything else you would like to add?

Let me just emphasise, this was a major collaborative effort involving more than 25 investigators, eight countries, more than 800 patients. We’re very pleased to announce that the study is being published in JAMA synchronously with the presentation tomorrow. So this also emphasises the quality of the study, that it was accepted by JAMA.