Practice Updates in Prostate Cancer Imaging - Episode 12
Lawrence Saperstein, MD, reviews the patient profile of a 65-year-old man with high-risk prostate cancer.
Neal Shore, MD, FACS: Let’s go to Larry. This is your case if you’d like to start with it.
Lawrence Saperstein, MD: A 65-year-old man had an MRI of the pelvis in 2021 that demonstrated suspicious lesions in the left peripheral zone and seminal vesicle. A biopsy in January 2022 showed a Gleason score of 10 for adenocarcinoma. PSA [prostate-specific antigen] was 6 ng/mL. I wouldn’t order imaging, so I’ll ask the group what they would do at this point.
Neal Shore, MD, FACS: How about you, Mike? What would you do? It’s December 2021. You’re in Maryland, and you have potential access to the 18F-DCFPyL. It’s probably too early before Gallium 68 was approved outside UCSF [University of California San Francisco] and UCLA [University of California, Los Angeles]. What are your thoughts?
Michael Gorin, MD: This is a patient for whom I’d order 18-FDCFPyL PET [positron emission tomography] CT, but I’m concerned that there may be already neuroendocrine phenotype, given the discordance between a PSA of 6 ng/mL and a Gleason score of 10. It’s already possible that on PET CT imaging with PSMA [prostate-specific membrane antigen]–targeted agents, we may be challenged in accurately determining the full extent of this patient’s disease. That’s where I stand. Because of that, I order a contrast CT as well.
Neal Shore, MD, FACS: That’s a good point. In neuroendocrine, for poorly differentiated small cell–featured patients, some of the literature that I’ve read and what you’re both saying is you may not see a lot of PSMA expression. That’s an important point. This is arguably 10% to 15% of patients. Nonetheless, Larry, do you want to continue with the PSMA PET?
Lawrence Saperstein, MD: We have the maximum-intensity projection image on the left. To illustrate the normal distribution, which is helpful for everyone to keep in mind, we see several lesions on the Tc-MIP-1404. Then we go to the axial-fused PET CT images. In the image on the top left, we see an area of markedly increased activity, a left seminal vesicle. In the adjacent perirectal region in the image next to it on the right, we see a markedly hypermetabolic presacral node. It looks like there’s another lesion in the left aspect of the prostate going down to the lower-left image. On the lower right, we see multiple bilateral—right greater than left—pelvic lymph nodes. It looks like obturator, presacral, and right pelvic sidewall.
Neal Shore, MD, FACS: Help us understand these cross-sectional images with the image on the left of the screen. Is there a true correlation?
Lawrence Saperstein, MD: That’s a 3-dimensional rendering of the data set of all the PET data. It gives us a 3D view of what we’re seeing. Then we switch to SPECT [single-photo emission computerized tomography] CT, which is our version of CT. We have the images in the axial plane. I want to stress that we certainly don’t limit ourselves to these planes. We read these in all the planes. That’s the sagittal, the coronal, and the axial because you can derive a lot of information from the other planes. But that’s a CT PET fusion rendering of the 3-dimensional data.
Neal Shore, MD, FACS: Do you think that the uninitiated, the nonexpert, might look at the axial and come away with a different conclusion from the transverse images?
Lawrence Saperstein, MD: A different interpretation from the 2 data sets? Is that what you’re saying?
Neal Shore, MD, FACS: That’s the thing I want to get across to the audience. It’s not the nuclear medicine radiologist or the radiation oncologist who’s doing the interpretation. To the busy urological surgeon, it’s how to best think about these findings.
Lawrence Saperstein, MD: I don’t want to speak for the surgeons in the group, but I’m thinking in 3D. I encourage you to start with the MIP-1404 so it gives you the lay of the land. In your mind’s eye, you then decide where that should be in terms of an axial plane and review the axial-fused images. Then review the unfused images. Those can add a lot of information. All those go into the process of interpreting.
Transcript edited for clarity.