MRI-US Fusion Targeted Biopsy Better Determines Prostate Cancer Significance, Risk

Herbert Lepor, MD

A new MRI technology may help make the diagnoses of patients with significant prostate cancer simpler for oncologists, according to Herbert Lepor, MD.

The technology, dubbed MRI-US fusion targeted biopsy, is one that gives a three-dimensional view of the prostate. This imaging is designed to allow medical professionals to only diagnose patients with significant prostate cancer, versus diagnosing patients with clinically insignificant prostate cancer that should not be treated. The imaging also provides medical professionals with adequate information regarding if men should pursue active surveillance, or if treatment should be discussed at the time of diagnosis.

OncLive: What exactly is a MRI-US fusion targeted biopsy?

In an interview with OncLive, Lepor, professor and Martin Spatz Chairman, Department of Urology, New York University School of Medicine, discusses the advent of the technology and what impact it could have on the field of assessing prostate cancer risk.Lepor: Historically, if the PSA was elevated, we knew men with an elevated PSA had a higher risk of prostate cancer. The only problem is that ultrasound was our diagnostic tool, and it really didn't show us where in the prostate the cancer was most likely to reside. The way we performed a biopsy was to do a random biopsy. We would just put 12 samples into the prostate, and we'd hope that we hit the cancer if one existed.

Here's what the possibilities were—one, you ended up having a significant cancer and we missed it. The other was that you had a significant cancer in the needle, we diagnosed it, and we cured a cancer that we needed to cure. About 30% of men over the age of 50 will have tiny, little, insignificant cancers, and those are of no clinical significance, but again if we did enough random biopsies then we could detect these cancers and then treat cancers that otherwise would have had no clinical consequences.

The real advantage of the multi-parametric MRI is that it's quite useful in identifying where in the prostate the indolent tumor or the aggressive tumor would reside. There are a couple of strategies, and it's technically easiest to do the biopsies under ultrasound guidance, as far as expense and efficient utilization of resources. What we've really pioneered at NYU is, taking the MRI and then the radiologist will give us a disc, which really shows us in three dimensions where the cancer is most likely to reside.

How has this technology improved clinical practice?

How common is this technology? What other institutions are using it?

We make a three-dimensional model with ultrasound. Now ultrasound is two dimensions, so we as spin the probe that's in the rectum and we can take hundreds of images of the prostate. Then what we do is we actually make a three-dimensional model by the ultrasound. Now I have the prostate MRI, I have the prostate with the ultrasound, and then we co-register the same structure, and once we do that, we fuse it and we transfer the target to the ultrasound and we're able to direct our biopsies to the area that's most likely to harbor the cancer.What are the results that we've reported out of NYU? It's exactly the diagnostic goals. We can actually increase the detection of significant cancers using this biopsy strategy and decrease the detection of insignificant cancers. So the real advantage of the MRI is detecting, preferentially the significant cancers, and then preferentially we end up treating the significant cancers. What our goal is, is then to preserve the current 40% reduction in prostate cancer mortality by doing fewer unneeded biopsies and treatments, and we feel that the use of MRI coupled with MRI-US fusion targeted biopsy is going to help us achieve that objective.At NYU, we started using multi-parametric MRI coupled with fusion targeted biopsy probably in 2012. We were one of the first centers to embrace this technology and we were one of the first centers to publish on this technology. Like all new technology, it really has to be proven in its utility until it becomes widely accepted in the urologic community.

Are there barriers to getting this technology more widely implemented?

I would say in 2014, at the AUA Annual Meeting, this was new. Some were hearing about it for the first time. Last year in 2015, the data was maturing. It was looking as though this was likely to change the diagnostic paradigm, and I would say in 2016, many centers were presenting that their experiences paralleled the early NYU experiences, being that we can increase the detection of significant cancer, we can decrease the detection of insignificant cancer, and hopefully achieve the goal of continuing to decrease prostate cancer mortality without unneeded harm to those whose cancers are actually best untreated and undiagnosed.There certainly are challenges. First of all, you have to have state of the art technology. Then you have to have the pathologists who are willing to take the extra time to do the necessary sequences. Then the radiologist has to get up to speed in interpreting the MRI because it isn't black or white. Our radiologists are very proficient with reading the MRI, and what they'll give us is a level of suspicion. This takes a lot of work from the radiologist, and ideally you'll have a lot of crosstalk between the urologist and the radiologist.