Practice Updates in Prostate Cancer Imaging - Episode 9
Dr Lawrence Saperstein describes the importance of coronal images and visual analysis in making a thoughtful treatment plan for prostate cancer.
Neal Shore, MD, FACS: Larry, how do we go about making the interpretation and helping both our radiation oncology colleagues and urologists at tumor board make a thoughtful consideration?
Lawrence Saperstein, MD: Great questions. I just wanted to comment briefly about that and reinforce what Mike said. The MIPs—the maximum intensity projection images on the left—are 3-dimensional renderings of the data set, right? In real time, these are rotating in a circle. And as Mike said, you can separate the activity in the lymph node from the somewhat tubular appearance of the ureter in this patient. I also want to stress that the SUV [standardized uptake value], while it can be helpful, the visual analysis is important for the interpretation. And what I mean by that is, how does the lesion’s activity compare to the normal structures in the patient? If you can look at the scan, we know there's liver activities, moderate. There's a lot of activity in the kidneys. What's interesting about the PSMA [prostate-specific membrane antigen] agents are the parotid glands. The salivary glands are very hot. And that's an important landmark to keep in mind as you're looking at these patients. They're proposed grading scores, and it's important if you think about immediate activity that is greater than the liver, but less than the parotid or high activity equal to, or greater than the parotid, those are the lesions that we're concerned about as suspicious for a prostate cancer.
Neal Shore, MD, FACS: That's a good point. Can you amplify that more? Again, looking at the SUV, uptake in the liver versus how it relates to positive findings. Is there any agreement across the specialty regarding above or below uptake in the liver?
Lawrence Saperstein, MD: That experience is evolving. But I would say, for the most part, it's just that the intermediate and the high uptake that is greater than the liver or equal to, or greater than the parotid, those are the concerning lesions. The SUV I would sometimes take with a grain of salt because it's a semi-quantitative number. But those are reasonable approaches. And as Mike said, using all the planes, right? The min, the maximum intensity projection is a 3-dimensional rendering. I would encourage people to look at the coronal images. And over the years, I've gained an appreciation for coronal images when looking at lymph nodes and prostate cancer. Those are all things to think about.
Michael Gorin, MD: One thing as well that we often talk about is, does the anatomical location make sense for prostate cancer metastasis? In this patient, that node is right at the bifurcation of the internal and external iliac—exactly where you would expect to see a lymph node metastasis. And regardless of the SUV value, I put more stock in that being a site of disease than had we found, say, an inguinal lymph node that had that level of uptake.
Lawrence Saperstein, MD: That's a great point. And what we always talk about is we don't read these scans as radiologists in a vacuum. We know the patient population, we know their risk assessment before imaging, so we know what we're looking for. Because there are tremendous amounts of variability. And as we do more of these scans, we're seeing more and more variants of uptake. And we'll talk about those as we get into the cases. Great point, though.
Transcript edited for clarity.