Phillip Koo: Hi, welcome to UroToday. This is Phillip Koo, and I'm very excited to be here to talk about prostate MRI. For all the viewers out there, I think we could attest to the fact that prostate MRI has really changed how we evaluate and diagnose prostate cancer. And it's exciting to see new data continue to be presented on the impact of prostate MRI, but also research talking about how prostate MRI can be performed, because as we all know, there have been a lot of controversies and discussions about quality of prostate MRI.

So there was a new trial called the PRIME trial that was published in the JAMA journal recently, and we're very fortunate to have with us today one of the authors and the lead radiologist on this trial, Francesco Giganti, who's from University of College London. And we're also very honored to have with us, Andrei Purysko, who's a radiologist at the Cleveland Clinic, to help sort of put this into context for us, especially here in the United States. So welcome to both of you.

Francesco Giganti: Hi, Phil.

Andrei Purysko: Hello, glad to be here.

Phillip Koo: So Francesco, let's start with you. This trial, it was randomized, prospective, very novelly designed. Can you talk to us a little bit about the PRIME trial?

Francesco Giganti: Yeah, thank you. So basically the PRIME trial is a multi-center study that was looking at the non-inferiority of biparametric MRI to multiparametric MRI. Basically what we did in this study was to acquire data and scans from 22 centers across the world in 12 different countries. And basically all patients had a multiparametric MRI, so the three different sequences, T2, diffusion and then contrast DCE sequences. And basically one of the most important things of this trial was that the radiologists were blinded to DCE sequences at the beginning. So basically they report just the T2-weighted imaging and diffusion-weighted imaging, and they provided the report for the biparametric part of the study. And then they were unblinded, the multiparametric studies to DCE sequences. And then they provided a new report, including the DCE sequences.

And so the findings on DCE patients underwent targeted biopsies, and for the lesions called both in biparametric and in the multiparametric reports. And what we saw, the results are pretty interesting because we saw that the biparametric MRI was non-inferior to multiparametric MRI in the detection of clinically significant prostate cancer, which was Gleason 3+4 or higher. And so there was no difference in the two approaches. But one of the most important things is that the quality of the scans and the quality of the radiologists reporting the scans for the study were very high. And this is a very important thing that we have to stress because we conducted also a quality control before starting the study. And so we evaluated the quality of all the scans for the centers taking part in the study, and we showed that they met the highest quality.

Phillip Koo: So multi-parametric MRI was T2 plus diffusion-weighted imaging plus the dynamic contrast enhanced imaging. And then biparametric was just the T2 plus the diffusion-weighted images, is that correct?

Francesco Giganti: That's correct, yes.

Phillip Koo: All right. So in terms of the centers, I imagine all of them were high volume centers with a lot of experience in prostate MRI or is that not correct?

Francesco Giganti: Some of them had less experience than others. So it was a mix of academic centers and non-academic centers, just to reflect of the heterogeneity of prostate MRI. But one of the most important things again, is that all the images were checked before starting the trial. We showed that scans were of adequate diagnostic quality or able to provide images of the highest diagnostic quality.

Phillip Koo: That's great to have central review to sort of confirm the quality. So something like this, it's non-inferiority, and it was proven to be non-inferior to the traditional prostate MRI. Andrei, from your perspective, is this ready for prime time, particularly in the United States?

Andrei Purysko: Yeah, so that's a great question, Phil. And first of all, congratulations to Francesco and the whole team because this is a critical data that we need to move the field forward with using biparametric MRI. And because the ramifications of faster scans, higher throughput and decreased costs will be essential to make sure that every man will get that prostate MRI when they need it.

In the context of the United States, I think we are ready for prime time, granted that we're doing it the right way. As we know, data from the American College of Radiology, about one in three scans in the United States may have suboptimal image quality. So that's one of the things that patients need to be aware of. They need to make sure that they're getting the scan with adequate quality, just like Francesco was describing, that happened in the setting up the trial.

Phillip Koo: All right, so in terms of the protocols, it's shorter. So how much shorter, Francesco, I guess this question might be for you. How much shorter is the biparametric acquisition as opposed to doing the multiparametric traditional acquisition?

Francesco Giganti: So strictly speaking, the DYNAMIC study, as per PI-RADS guidelines should last at least two minutes. Overall, we have seen that the majority of the centers perform a four-minute DCE acquisition. So at least four minutes. But then of course we also take into account also the time for cannulation for example, and to remove the cannula. So all of these things together, I would say they might result in 10 to 15 minutes.

Phillip Koo: So 10 to 15-minute reduction in time.

Francesco Giganti: Overall, but in terms of the actual sequence, it's just four to five minutes.

Phillip Koo: All right. And then how long does a prostate MRI typically last? How much would you schedule?

Francesco Giganti: So the multiparametric MRI is between 30 and 40 minutes.

Phillip Koo: All right. So that 10 to 15-minute reduction is pretty significant and it clearly would allow for more patients to get through on a camera as opposed to the traditional methods.

Francesco Giganti: Yeah.

Phillip Koo: So in the UK, you guys have been leaders in prostate MRI. I remember some of the old trials that really led to this with regards to using it before biopsy. Is this becoming standard of care in the UK?

Francesco Giganti: Well, I think we're not there yet. So basically we provided the first study showing that biparametric is non-inferior to multiparametric. But as we say also in the paper, one of the biggest things is this study is that we all had experienced radiologists looking at very good quality images. And we know that this is not always the case. We still see a lot of centers that are not meeting, for example, the PI-RADS guidelines for how to acquire a good quality MRI. And the radiologists, not all of them are skilled genitourinary radiologists. So I think if your scan is of adequate diagnostic quality and you have a very experienced reporter, then we might consider the biparametric scan for certain settings, for sure.

Phillip Koo: So the use of a biparametric is really incumbent on having an experienced reader to go along with it?

Francesco Giganti: Yes, correct. Because what we did before the PRIME study was another study that we published before that was the GLIMP study. We looked at the scans submitted by the centers interested in taking part into PRIME, and we saw that the sequence with the highest variability was DCE sequences. So what we did, we said to all centers to improve the quality of the different sequences. And we saw that after this feedback, the centers were able to achieve the highest diagnostic quality using the PI-QUAL v1 score. And this was a PI-QUAL score of five out five, which means optimal diagnostic quality. So with minor tweaks you are able to improve the quality of your scans.

Phillip Koo: So it seems like the ability to achieve a quality scan actually becomes easier if you're not doing the dynamic contrast enhanced acquisition. Am I right or wrong there?

Francesco Giganti: It's not, basically you have some parameters for each sequence, right? For T2 diffusion and DCE sequences. What we have seen is that we have to work on each separate sequence, and then overall we will have the diagnostic quality of the whole scan. But of course we can have diagnostic T2 for example, but non-diagnostic diffusion-weighted imaging for the presence of artifacts, for example. So if we have, for example, patients with a hip replacement or a lot of rectal air, we haven't prepared the patients adequately, then DCE, for example, in this case is a safety net. So it's really important to have contrast in this case if we're not there on the table and helping our radiographer to acquire the images again. So again, DCE can also be seen as a safety net when the diffusion, for example, is non-diagnostic.

Phillip Koo: I think that's a great point that each patient in each case is very unique, and I think a lot of times patients just assume you go to any center, you go to any magnet, you're going to get the same output, which is not true.

So Andrei, you chair the ACR Prostate Imaging Center of Excellence program. How do you foresee this becoming more standard of care in the United States, especially under that larger umbrella of quality that you oversee?

Andrei Purysko: Yeah, so that's another great question, and I think sooner or later from a cost perspective, there will be some interest in adopting biparametric MRI and make it streamlined for the population just in general. I mean, as Francesco highlighted, some patients, particularly those with hip prosthesis where we need a safety net, biparametric may not be the most adequate test. But if we want to make it sort of the default for most patients, we'll need to make sure that the scans are done with high quality.

And I think patients will need to look for centers that have some documented quality metrics. I think the designation provided by the ACR is a good example of that, where we ensure that the sites are not only using the technical standards that are defined by the PI-RADS committee, but also they have mechanisms in place to make sure that the physicians have the right expertise, that there is feedback between pathology and radiology so that we are able to catch discrepancies in biopsy results, for example. So this will be critical, having in place a QC process to make sure that we're offering high quality scans, will be essential.

Phillip Koo: No, I think this is really exciting. I appreciate both you coming on to sort of help clarify and help us all understand this better, especially for those urologists out there who order these every day. Great to see research continuing to grow in this space, and I'm sure there's more to come that'll make this tool even more valuable for all of our patients. So thank you both for joining us today.

Andrei Purysko: Thank you very much.

Francesco Giganti: Thank you. Thank you.