7 Q&A with the Faculty

Q&A Session on Prostate Imaging Cases

Okay.
Any questions from the audience? Go ahead.
The last case you showed looked like the size.
So the question was whether the size in the last case of this circumscribed exo nodule was the dominant finding over the others?

This case is just an example of how difficult sometimes the assessments are and was one of the reasons we actually included size, which was not part of the first PIs scoring.
And the fact that this was exo and I didn't show you more images different than the remainder of the gland abnormality that was positive on all the sequences, except it had this con sort of bound margin to it.
And the ductile carcinomas actually can grow in this fashion.
So this is sort of one of the extreme cases where it may be quite hard, but when you look at the individual parameters and remember we are looking at the in quotes our likelihood and confidence of us calling something to be to biopsy or ignore type of abnormality.
So if we extend this to maybe three, because we are not sure, we still would have come at four, which probably would have translated to biopsy in any practice.

Other questions out there? Go ahead.
The question is at three t cause of gas and the rectum, the diffusion scans are sometimes compromised.
We're gonna be talking about that some more.
There's gonna be a talk on technical issues, and then I'm gonna also talk a little bit about that very specific issue later.
Okay. But it is a concern.
The case is multiple. Okay.

PI-RADS Assessment Categories

So the question is, is the RADS assessment category, does that pertain to the entire to the patient or per lesion?
It's per lesion. So you're supposed to assess up to four lesions that are either a three of four or a five.
Okay. But it's per lesion, there is no overall patient is a ed, so and so, and you should identify the index lesion.
Let me go to the other side. There. It was, oh, go ahead.

Total PSA vs. Free PSA

So the question is, what is total PSA versus free PSA and how valuable is that?
And so when people talk about screening, they generally talk about total PSA, which has a bound and an unbound component.
It normal PSA is stickier, so it binds to protein, so that's bound.
And the unbound component is the free PSA, which is as the percentage of that increases, or conversely, if the amount of bound decreases, then there's increased concern that there's actually a cancer that the PSA is being generated not by BPH, but rather being generated by cancer that is used in the community.
There's no question about it.
But it has not proven to be super reliable.
And so to say that it it's significantly better than the total PSA is not really a true statement.
It helps and some people do it, but I don't think there's general endorsement of it as a means to separate who has cancer and who doesn't.

I wanna make correction to an answer that I gave during the q and a about free and total PSA, I had it backwards.
The free is more associated with benign.
So the lower the free, the worse the situation, the higher the risk for cancer. Okay.

Other questions? Let me go to the back of the room there.
All right. Okay. Good, good question. Cause it may have been a little confusing.

Reporting PI-RADS Scores Across Zones

The question was both Kasha and I talked about in the peripheral zone diffusion weighting is the dominant factor that you want to use for your assessment.
And in the transition zone is the T two weight images.
But regardless of where you are, you should report what your score is for T two, for DWI and for DCE.
And that will and then give your overall assessment.
So the reach, so it's a five point scale for a T two, a five point scale for DWI, whether you're in the transition zone or the peripheral zone and a positive or minus for DCE.
And then you give a one to five overall assessment for that lesion.
Go ahead. Just

Defining Significant Lesion Size

So significant volume 0.5.
Okay. Masu, you wanna take that? So the question is what's the size of a significant lesion, if I can summarize that correctly.
So I think there we face a problem, and the problem is that a significant lesion on pathology has generally on pathology, not on imaging, has been set, the threshold's been set at 0.5 CCS volume on pathology, but the correlation between pathology and the measurement of the volume of a tumor on imaging is not great.
So I think once we see a lesion on mr, and typically these lesions that we're seeing consistently are over about four to five millimeters in diameter on the imaging, you're getting into the realm of something that has a higher likelihood of being clinically significant, but the actual idea that a one centimeter diameter lesion, so if you just do a four thirds sort of, or a 0.5 times one times x one times one, you gotta have cc the idea that that is gonna be a half cc pathology.
Measured volume is not always the case.
Often we're underestimating the true extent of the tumor.
So it's something that has not been defined yet for us as a radiologic measure of size.
I say one other thing very quickly and that is the selection of the 1.5 centimeter threshold in PY rads in that sense does not have a strong basis in the literature.
It's just a number that was chosen.
I don't even think I can tell you the rationale for why it was chosen, but it has been chosen, we'll have to see what the optimal number is gonna be in the future.
It was a there was a the we came to a consensus agreement that size should somehow factor into the likelihood that a finding is a cancer.
And 1.5 was a I'd say consensus number that the pathologist that we consulted with said That's fine, but it could easily have been one, it could have been two.
It's just a number and we're just trying to standardize.
And over time we'll learn what numbers if that's not a good number, we'll come up with another one. Yes.

Importance of DCE in PI-RADS

Question from you, Jeff. How important is dce? So the question is, how important is DCE in the pirates classification?
And do we have to give contrast?
It's a great question because we we've discussed this and so what I'd say is within our group and also with people we've talked to, and this this is definitely a trend.
The movement has been against using DCE as a primary determinant.
Nevertheless, as a group, we decided that sometimes it's useful and there are cases, as we've already heard, where the DWI doesn't come out well, and then you have at least something to fall back on.
So and also we're not looking where DCE is a very complicated subject.
Peter actually led that working group.
There may come a time, maybe somewhere in the future where there's some parameter that you can derive.
If we standardize the way we do DCE, that will actually be extremely useful.
But at this point in time, we decided that it's the least useful, but we still think we should acquire it.
There is a possibility somewhere in the future where we may say you know, we don't need it.
But I don't know that we're we decided we're not at that point yet.
Maybe Peter, you can comment cause this was your working group. Yeah.

So yeah, I fought a rear action to protect D-C-E-M-R-I.
And as you can see, I almost got totally defeated.
So it's it is we believe that it is useful, just as Jeff said, in certain instances where the other parameters are not that good also in increasing confidence.
But I do foresee a day when we will have a level one type scan that doesn't involve D-C-E-M-R-I at all, and perhaps a level two type scan that involves that DCE plus other things.

DCE Imaging Features

Just a follow up question.
Yeah. So the question is, what is the most important feature of A DCE washout?
Either the wash in or the wash out.
And honestly that is very difficult to get good data on.
I will discuss it in my talk right after lunch, but it's hard to get very good data.
There's no question that cancers are associated with a rapid wash in and they're associated with a rapid wash out, which one of these is more important, is not clear, recent literature and suggests that it maybe the wash out that's more predictive than the wash in.
Okay. So somebody also wrote down a question, so I wanna read it to you.

Diffusion Weighted Imaging Preferences

Do you find DWI or high B value images most useful, or do you always compare both of them?
So the we acquire the DWI, you're gonna get a talk on this very after lunch about diffusion weighted imaging.
So the short answer is we acquire DWI images with multiple B values to generate an a DC map.
But the ones you most wanna look at are the a DC map and then the very high B value image, which you can either calculate or acquire.
And you'll understand more about how this works.
After the talk on diffusion, I think we're gonna have to stop now.