29 Q&A with the Faculty

Anticipation of Increased MRI Demand and Scanner Considerations

In anticipation of increased numbers of MRIs.

We already, we've just started an MR Prostate.

We're looking into buying a, getting a new magnet.

I noticed, on the chart earlier, all of you all are working on A three T.

Although there are options for 1.5 T in the case of a prosthesis or something, how important do you think, the three T is?

We currently run on two new GE one point fives and I think get good quality images, but we do not have a three T option.

How important do you think that would be?

Importance of 3T vs. 1.5T Scanners

I think the current, one and a half T scanners without an ENDORECTAL coil can actually do pretty well.

I don't know if that's, I presumably that's your experience as well, since you're comfortably doing that.

I think that you just need to be aware of limitations.

I think that doing the dynamic contrast and hands to imaging is an important, becomes more important and your experience becomes a more important.

So you've gotta be able to pick up more subtle findings and be able to develop a high level of confidence in calling them fours and five py rads fours and five.

So what I've found is, is that the experience I've developed doing endorectal coil imaging at one and a half t and doing three T imaging has helped me in interpreting non endorectal coil one and a half T imaging better.

And so that's, that's what I would say about It.

And I will also have a comment that, with contemporary multi-channel coils, we really get boost in SNR.

So it's important to perhaps looking at the, coil setup for your, hardware.

I think in, in the, py rads, we were very careful.

We had lots of discussions.

Most of the people who were involved in developing RADS are using three T systems.

But, and, and there is, there are signal to noise issues.

The, the diffusion weighted scans are really, very signals, poor images.

So you need all the signal to noise you can get, but it's really, we decided that it would be completely unfair to say that three T is okay.

1.5 T is not okay.

'cause there are contemporary 1.5 T scanners that are great, getting great signal to noise.

And there are other, there are some three T scanners that do really poorly.

But we did decide to draw the line at 1.5 T and, and not say that you can do this at any field strength, but I, I think what's gonna have to happen, and it's hard for us to say you need, you can't tell, you need this amount of signal to noise some point.

If you are using any kind of skin, you're gonna have to compare it to what other people are doing.

That's why we're gonna have this atlas.

Part of the reason for having this atlas online is you'll be able to go to this atlas online and look at how you images look compared to what's out there and make some decision about whether they're really good enough.

If the images are not good, I'm telling you, you will not be able to read the scans because I, I'm sure you saw lots of examples up there that, boy, if you didn't have those arrows and these experts pointing to things, there's no way on earth you'd see it.

It's a little bit like a Rorschach test and particularly in the transition zone, you need good images.

Okay.

I would just say that if you've got two one fives, you might have a good reason to go to three for lots of reasons and that you don't have one yet and there's other organs in the body.

So, and I do think it's important for us to keep getting better rather than staying the same.

I do think it is an imp and it's a challenging area, and I think three T is for that transition zone area.

I like the T twos at three T better than, than most anything I've seen at 1.5.

I really think that's such a hard place that we should be putting all the signal out possible.

So I've set the bar at three T, but I do agree the Europeans and many people have published good stuff and it's optimization of what you have is always what's the, the bottom line.

Yeah.

And I think for, abdominal, applications you saw out at three TA lot.

So there 1.5 T makes sense, but we almost never saw out, for our, prostate mar.

So the boost in SNR means you can scan that much faster and maybe schedule a couple extra patients.

Audience Questions

Okay.

So we have a, a number of questions from people who are joining us versus the, webinar.

And, so let me run these by you, including, some people we know at, academic institutions who've been following this, course very carefully.

Focal Therapy and Gleason 4 Disease

So, question for Dr. Ani, that you mentioned that focal therapy patients should not have any Gleason four disease, small volume, Gleason four seems like a great target, population since three plus four low volume disease may go into active surveillance today.

Can you comment on that?

Yeah, I don't have, a lot to base this on.

Primarily it's because I think the urologists and the, and the radiation oncologists are so worried about that Gleason four that I think there and there's just that learning curve still about focal therapy and there's this sort of generalized unacceptance of it still broadly that most publications will suggest.

That's not a good idea.

But I agree.

I think that certainly small volume three plus fours probably could be good candidates for focal therapies.

The literature, that was just one article I was using just as a framework for the talk.

Um, okay.

Any other comments?

No, I was gonna say that, you know, when we started doing this and limiting this to low risk in Toronto, with, we would just say, okay, Gleason six or low risk category, without bringing in the low to intermediate risk patient, we started to find a lot of MRS were negative, which is kind of what you'd expect given all the published data.

So here we have a trial running yes, trying to evaluate focal therapy, and we don't see anything in half the patients when they come for an mr, how are you gonna do focal therapy?

So I think, I think whatever the people say they want to do, if they're not gonna do mapping biopsies on every patient and they want to use MR to localize disease and treat it, you're gonna end up in the low to intermediate risk group whether you want to or not.

So That's a good point.

I agree.

Significance of Positive Surgical Margins

Um, another question from, one of the, participants from outside is what is the significance of positive surgical margins?

Are there papers showing that MR decreases the rate of positive margins?

So it's sort of two questions.

Who wants to take that one?

We Wrote a paper about that, so let me try it.

So the first question was, what Is the risk?

What is the significance of positive surgical margins?

So the significance of it is that there's obviously high risk of local recurrence.

Um, most of the time patients who have pathological diagnosis of a positive margin, meaning tumor, has been cut through and left behind, will require as a, a salvage treatment.

They'll go from surgery to radiation, they'll get localized radiation because of that risk issue.

So that's the answer to the first one.

And then can MRI change that?

We've shown in a single surgeon's practice in one paper that we wrote maybe, I dunno, 10 years ago, perhaps, that it can, by showing the surgeon that where the tumor is located and then determining that he can, he should obviously do a slightly wider resection located near the, where the tumor is, be it right or left or at the apex.

So yes, it can definitely change that.

Yeah.

And, and Hedy Resach, published in 2004 in in cancer, her experience, looking at the change in surgical plan where she found that there is a, the surgeons were able to determine whether or not they resect the neurovascular bundle, without an increased, rate of positive surgical surgical margins.

And then we reproduced that for robotic technique in in 2012.

Okay.

So the answer is, there is data showing that Mr. R decreases the rate of positive surgical margins.

So, so that's tricky.

We, we showed that we did not increase the rate, but decrease it is a little harder to show.

Hmm.

Risk of Sepsis or Abscess After TRUS Biopsies

Okay.

The question, this one's for, Dr. Ani, that she refers to studies that show a 20% risk of sepsis or abscess after trusts.

Um, and the, quest, the statement here is that large studies show a one to 4% risk in the us, Canada, and Europe.

No, I don't think the European literature is that good.

Um, I can't cite chapter and verse.

My brain is not that smart at this time of the day.

Um, Dan is very good at citing chapter and verse, so maybe I'll let him jump in in a minute.

'cause he's much younger than I am.

But, no, the Europeans are very worried about this, and I don't, I, again, as like I say, I can't remember, but I know that having spent time at UCL, they're very concerned.

And so many, I heard Bill DeWolf, who's a, a urologist in Boston speak about this two weeks ago.

And one of the things they've all started trying to recommend doing is rectal swabbing of the, rectal wall prior to surgery to determine the antibiotics, or excuse me, prior to trus biopsy, to determine whether the correct antibiotic regime should be prescribed.

So I think there is a general trend to worrying more and more about it.

And I know I've seen at least one paper that quoted 17%, and again, I'm sorry, I don't have the exact citation.

So, I think the overall numbers are in the one to 4% range, but what's very, very clear in, in support of Dr. Temple's point is that, the rate of significant, complications including hospital admission and, euro sepsis requiring, hospital treatment is going up and it's going up significantly.

Antibiotic regimes are being changed, but there's expense, and concern about the public healthcare scenario around that.

So there's no question it's a real problem.

Uh, but the numbers I'm familiar with, a little lower than 20% going In North America goes of antibiotic resistance, Presumably.

Yeah.

Yeah.

But that, that's the North American stuff.

And also I'd learned to mention at Hopkins, Recile swab is now routinely implemented and the antibiograms are also routinely used.

And we also, in radiology, when we do biopsies of patients, we, tend to rely on the data too.

Correcting for Prostate Shrinkage in Radiation Therapy

Okay.

Um, question about, rt, when using M-P-M-R-I to define a boost volume for rt, how do you correct for prostate shrinkage caused by hormone therapy?

You know, that, that's an interesting question.

Um, a lot of times we'll do the M-P-M-R-I, right before the, the start of treatment and we'll define the, the boost area, the, the target, based on that.

But, as you know, and as you saw from the example, the prostate will shrink, the character will change, both from the radiation therapy and the hormone therapy.

Um, ideally when the patient, comes for each of their visits, the prostate is re contoured, and so shrinkage should be compensated for, because the, radiation oncologists generally use a deformable co-registration technique.

Um, but also they tend to paint with a broad stroke around that, that target volume.

So usually they're, they're not trying to, to target it as tightly as, you know, we contour it, because they also recognize that we underestimate the total volume.

Reasons for Decreased Prostate Cancer Mortality

Okay.

Here's a question.

This is, you know, it's nice to know people are really, paying attention and, really following every word that's been said here.

Um, it's very interesting, some of the comments I'm getting on my, phone and also some of the ones that are being, texted to the, folks in back.

So here's, here's the question.

Um, this was directed to Peter Choki because he commented on this in one of his talks, but he's not here right now.

So hopefully, the panel here can comment on this.

Um, if there, so Peter showed pretty powerful data in his first talk that the mortality from prostate cancer has decreased from 40 in a hundred thousand in 1993 to about 25 in a hundred thousand.

And the question is why, um, we have heard so much about PSA not improving survival and radical prostatectomy not improving survival, and how there are a few drugs that work and radiation therapy and hormones have been around forever.

So where's the benefit coming from?

Why is the death rate gone down?

I think there's a lot of factors.

So when, when you look at the American and the European That you're supposed to say 'cause of MRI, Oh yeah, sorry, because of MRI, but also, when you look at the American and the European literature looking at PSA screening, the benefits were mostly shown in the European literature.

And a lot of that is thought to be because there was less contamination of the sample.

So once PSA became available for screening, it's really hard to keep a clean control population that doesn't get screened at all.

Um, and so the Europeans did a little better at that, and they actually proved that, there was a reduction in mortality, but also, we have better treatment techniques.

Um, and, we have, other a, adjunct techniques to extend, life after treatment.

So hormone therapy has been around for a long time, but not abiraterone, not a lot of the, not enzalutamide, a lot of, not the techniques that we use now.

Radiation therapy has been around forever, but not, SBRT, not, high dose brachytherapy.

So, and granted those are relatively new, but as the science has progressed, we're seeing this extension in survival for a lot of,

And one of the obvious reasons also is that if you treat men with Gleason three plus three disease, one core positive, 1% of the core, you cure them.

Right?

Well, they would never probably have died of that disease in the first place, but they get registered as a cure and a survivor.

Closing Remarks

Any other questions from the audience?

Okay, then I think we'll, you guys have any questions, any comments you wanna make?

No.

Alright, then let's move on to the, concluding session.