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Disease Spotlight: Prostate Cancer

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RSNA 2023

Rad View: PSMA PET Imaging Recommendations

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6th Annual Precision Medicine Symposium: An Illustrated Tumor Board

William J. Gradishar, MD, FASCO, FACP; David M. Schuster, MD; Eleanor Harris, MD; Joseph A. Sparano, MD

Clinical Vignettes™: The Experts Explain How They Integrate PET Imaging into Metastatic HR+ Breast Cancer Care Settings

Joyce O’Shaughnessy, MD; William J. Gradishar, MD, FASCO, FACP; Kevin Kalinsky, MD, MS; Terry P. Mamounas, MD, MPH, FACS;

School of Breast Oncology® Live Video Webcast: Clinical Updates from San Antonio

Annual Hawaii Cancer Conference

Reshma Jagsi, MD, DPhil; Kevin Kalinsky, MD, MS; Hope S. Rugo, MD, FASCO; Alastair Thompson, MD, MBChB, BSc (Hons), FRCS (Ed), FACS; Debu Tripathy, MD


Clinical Case Vignette Series™: 41st Annual Miami Breast Cancer Conference®

The clearance may facilitate improved standardization and efficiency of dosimetry-guided, theranostic applications of radiopharmaceutical therapy.



FDA Clears Automated Dosimetry with the Monte Carlo Method for Radionuclide Therapy 

Offering higher diagnostic efficacy than SPECT imaging for coronary artery disease (CAD) detection, the PET myocardial perfusion imaging agent Flyrcado™ (flurpiridaz F 18, GE HealthCare) provides unit dose availability and effectiveness in imaging patients with high BMI.

Radiology ‘Game-Changer’: FDA Approves PET Agent for Enhanced Detection of Coronary Artery Disease

Now available with MIMneuro, the Centiloid scaling software provides automated quantitative assessment of amyloid plaque density, a key component of Alzheimer’s disease.

FDA Clears PET-Based Software for Centiloid Scaling of Amyloid Plaque Density

Results from a multicenter phase 3 trial showed that the PET/CT imaging agent (89Zr)Zr-girentuximab had an 85.5 percent mean sensitivity rate for the diagnosis of clear cell renal cell carcinoma.

Study for Emerging PET/CT Agent Reveals ‘New Standard’ for Detecting Clear Cell Renal Cell Carcinoma

The imaging agent 18F-FAPI PET/CT demonstrated greater than a 45 percent higher sensitivity rate in comparison to 18F-FDG PET/CT for the detection of axillary and extraaxillary regional lymph node metastases, according to a lesion-based analysis from a recent study.



Researchers Show Higher Breast Cancer Upstaging Rate with 18F-FAPI PET/CT

In separate studies presented at the recent 

, the positron emission tomography (PET) radiotracer 

F-flotufolastat demonstrated no urinary retention in patients with primary prostate cancer (PCa) and facilitated a 15 percent higher percentage of biochemical failure-free survival in comparison to conventional imaging for guided salvage radiotherapy in patients with recurrent PCa.

In one study comparing 18F-flotufolastat (Posluma, Blue Earth Diagnostics) and 

, researchers found that 18 percent of primary tumors located near the bladder in the 

Ga-PSMA-11-PET group (3/17) were obscured by radioactivity in the bladder in comparison no obscured tumors with 

F-flotufolastat (0/24). The study authors also reported a 27.4 percent rate of halo artifacts with the 

Ga-PSMA-11-PET cohort (17/62) in contrast to 4.8 percent (3/62) for those in the 

The researchers also emphasized that there was no ureter retention with 

F-flotufolastat in comparison to 21 percent (13/62) for men in the 

David Gauden, D.Phil, discussed these study results during an interview at the SNMMI conference.

“Their findings were clinically impactful in their opinion in that they had a much lower background radioactivity in the bladder (with 

F-flotufolastat) when they were evaluating the scans. (This) gave them more confidence in their diagnostic findings when they evaluated it on a multi-point scale of background (radiopharmaceutical) activity, leading them to believe that when you’re looking for local recurrences, using an agent with this lower bladder excretion could be clinically valuable in helping with the management of these patients,” noted Gauden, the chief executive officer for Blue Earth Diagnostics.

(Editor’s note: For related content, see “

Study: 18F-Flotufolastat PET Imaging Changes Treatment in 89 Percent of Patients with Prostate Cancer Recurrence

Could Pluvicto Have a Role in Taxane-Naïve mCRPC?: an Interview with Oliver Sartor, MD

SNMMI: PSMA-18F DCFPyL Changes Treatment for PCa Recurrence in Significant Number of Patients with Low PSAs

In a separate study of 110 patients with biochemical recurrence of PCa after radical prostatectomy, researchers compared 

F-flotufolastat PET-guided salvage radiotherapy (SRT) to conventional SRT. Although the researchers conceded a lack of statistical significance, they found that the 

F-flotufolastat PET-guided group had 8 percent, 15 percent, and 21 percent higher rates of biochemical failure-free survival at one, two and three years, respectively, than those who had conventional SRT.

“Although it was a small study without a statistically significant finding, there were trends toward longer biochemical progression-free survival for the group where the radiotherapy was guided by PET imaging in addition to the standard field … ,” added Gauden.

For more insights from Mr. Gauden, watch the video below.

David Gsuden, D.Phil, discusses new research, presented at the SNMMI meeting, that examines use of 18F-flotufolastat in patients with prostate cancer.

Emerging Research at SNMMI Examines 18F-flotufolastat in Managing Primary and Recurrent Prostate Cancer

1. Rauscher I, Langbein T, Fuetterer CS, Weber W, Eiber M. Evaluation of qualitative and quantitative PET parameters in primary prostate cancer patients: double-match comparison of 18F-flotufolastat and 68Ga-PSMA-11-PET. Presented at the 2024 Society of Nuclear Medicine and Molecular Imaging Annual Meeting, June 8-11, Toronto, Canada. Available at: 

https://www.xcdsystem.com/snmmi/program/10OD8Tq/index.cfm

2. Rauscher I, Vogel MME, Gschwend J, Peeken JC, Eiber M. 18F-rhPSMA-7 and 18F-flotufolastat PET-guided salvage radiotherapy in recurrent prostate cancer. Presented at the 2024 Society of Nuclear Medicine and Molecular Imaging Annual Meeting, June 8-11, Toronto, Canada. Available at: 

In a recent interview at the SNMMI conference, David Gauden, D.Phil, discussed key findings from new research evaluating the use of the PET radiotracer 18F-flotufolastat in patients with primary prostate cancer (PCa) and men with biochemical recurrence of PCa. 

Emerging Research at SNMMI Examines 18F-Flotufolastat in Managing Primary and Recurrent Prostate Cancer

The radiopharmaceutical agent (177Lu)Lu-PSMA-617 (Pluvicto, Novartis) may be a viable option in the treatment of patients with taxane-naïve metastatic castration-resistant prostate cancer (mCRPC), according to emerging research findings presented at the 2024 Society of Nuclear Medicine and Molecular Imaging (SNMMI) Annual Meeting.

, Oliver Sartor, MD, said there are reimbursement challenges as well as mixed results with current androgen receptor pathway inhibitor (ARPI) treatment in this patient population.

“We know (ARPI therapy) is a viable alternative, but we also know these patients will progress and go on to need additional therapy,” noted Dr. Sartor, the director of radiopharmaceutical trials at the Mayo Clinic in Rochester, Minnesota.

In new research, which garnered Abstract of the Year honors at the SNMMI conference, researchers compared the use of Pluvicto versus a change in ARPI therapy (abiraterone or enzalutamide) in 468 taxane-naïve patients with mCRPC.

In the primary study analysis, the researchers found that patients in the Pluvicto group had a significantly higher median radiographic progression-free survival in comparison to those in the ARPI change group (9.3 months vs. 5.55 months). A second interim analysis revealed that patients in the Pluvicto group had over a 35 percent higher objective response rate (50.7 percent vs. 14.9 percent) and a significantly longer median time to PSA progression (10.55 months vs. 4.24 months) in contrast to patients in the ARPI change cohort.

Dr. Sartor, a co-author of the study, also noted that the second interim analysis showed a lower incidence of grade > 3 adverse events in patients receiving Pluvicto.

Emerging Perspectives on PSMA PET Radiotracers: An Interview with Kenneth J. Pienta, MD

Study: PSMA PET/CT Agent May Rule Out csPCa in 93 Percent of PI-RADS 3 Lesions

While Pluvicto was approved by the FDA for patients with PSMA-positive mRCPC who previously had ARPI therapy and taxane-based chemotherapy, Dr. Sartor suggested there is “reasonable hope” for an expanded indication for Pluvicto in the management of patients with taxane-naïve mRCPC.

“If the FDA does give an approval, it will truly be practice-changing, Insurances will cover it and patients can be treated,” added Dr. Sartor.

For more insights from Dr. Sartor, watch the video below.

Oliver Sartor, MD, discusses the potential of Pluvicto in treating metastatic castration-resistant prostate cancer in taxane-naive patients.. 

Could Pluvicto Have a Role in Taxane-Naïve mCRPC?: An Interview with Oliver Sartor, MD 

In an interview at the SNMMI 2024 conference, Oliver Sartor, M.D. discussed key findings from new award-winning research evaluating the potential of Pluvicto in treating patients with taxane-naïve metastatic castration-resistant prostate cancer (mCRPC).

Could Pluvicto Have a Role in Taxane-Naive mCRPC?: an Interview with Oliver Sartor, MD

A longtime researcher who has over two decades of experience in the development and assessment of radiopharmaceuticals, Cathy Cutler, Ph.D., said she is excited about the increased patient interest in positron emission tomography (PET).

“We’re at a point where patients know so much more about PET and they’re asking for this. They want to ensure their doctors have these tools to better inform their therapies. It’s exciting to see that. When you talk to patients, they’re out there now fighting with us to help make sure they have access to PET imaging, It’s not where I thought we would be about 20 years ago but it’s very exciting to see that is where we are today,” noted Dr. Cutler, the new president of the Society of Nuclear Medicine and Molecular Imaging (SNMMI).

Dr. Cutler said it’s important to build upon that enthusiasm in recruiting talented people into the field. Through recent surveys conducted through the SNMMI’s workforce pipeline, Dr. Cutler noted significant numbers of pending retirees so there is increasing urgency to ramp up recruiting efforts. Noting a visit to a local high school in Toronto by SNMMI leaders during the conference, Dr. Cutler said video testimonials from physicians, scientists, and technologists about the benefits of the field are also being shared with younger audiences to help spark interest.

As the director of the Medical Isotope Research Production and Development Group at Brookhaven National Laboratory in New York. Dr. Cutler said isotope availability is an ongoing challenge with demand likely to increase as more radiopharmaceuticals are utilized in patient treatment. Appropriate reimbursement is another challenge in the field, according to Dr. Cutler.

“Unfortunately, the CMS … looks at diagnostic radiopharmaceuticals as supplies, kind of like gloves so they basically bundle the costs,” posted Dr. Cutler. “It turns out those costs really don’t cover what it takes us to manufacture those drugs.”

SNMMI: Study Shows Viability of FAPI PET/CT for Predicting Progressive Pulmonary Fibrosis in Lung Disease Patients

Meta-Analysis Assesses Impact of PSMA PET/CT for Staging of Renal Cell Carcinoma

Study: PSMA PET/CT May Rule Out csPCa in 93 Percent of PI-RADS 3 Lesions

For more insights from Dr. Cutler, watch the video below.

New SNMMI President Cathy Cutler, PhD, discusses key challenges and goals in nuclear medicine.

New SNMMI President Cathy Cutler, PhD, Discusses Current Challenges and Goals for Nuclear Medicine

In a recent interview, Cathy Cutler, Ph.D., shared her perspective on a number of topics affecting nuclear medicine, ranging from isotope availability and reimbursement challenges for diagnostic radiopharmaceuticals to increasing patient interest in PET imaging.

New SNMMI President Cathy Cutler, PhD Discusses Current Challenges and Goals for Nuclear Medicine

A higher amount of visceral abdominal fat in one’s midlife years may be an early warning sign for the development of Alzheimer’s disease, according to magnetic resonance imaging (MRI) and positron emission tomography (PET) findings recently presented at the Radiological Society of North America (RSNA) conference.

In a cohort of 54 cognitively healthy people with an average body mass index (BMI) of 32, researchers found that a higher amyloid PET tracer uptake in the precuneus cortex, a brain region known to show early pathological sings of Alzheimer’s disease, was associated with a higher ratio of visceral abdominal fat to subcutaneous fat.

“Showing this association in midlife in individuals with obesity highlights that we are observing early amyloid pathology in the Alzheimer’s (disease) signature areas 20 years before the onset of Alzheimer’s disease,” noted Mahsa Dolatshahi, M.D., M.P.H., the lead author of the study and a postdoctoral research scholar affiliated with the Mallinckrodt Institute of Radiology at Washington University, in a recent video interview.

Emerging Neuroradiology Concepts: Could Tau-PET be a New Standard in Assessing Possible Alzheimer’s Disease?

FDA Clears AI-Powered MRI Software for Brain Atrophy

Brain PET Study Suggests Link Between Early Amyloid Accumulation and Repetitive Subconcussive Trauma

Cyrus A. Raji, M.D., Ph.D, said the long relied upon body mass index (BMI) is an “imperfect measure” for characterizing body fat. In taking a closer look at the anatomically specific distribution of visceral fat and subcutaneous fat and its relationship to the risk of developing Alzheimer’s disease, Dr. Raji noted the preliminary research findings have many potential implications for early intervention.

“By characterizing the actual distribution of fat and the biophysical profiles, we can really start building an idea of who needs a more aggressive form of lifestyle intervention or related drug therapies,” explained Dr. Raji, an associate professor of radiology and neurology at the Mallinckrodt Institute of Radiology at Washington University. 

“This will not only decrease the risk for Alzheimer’s disease for people at midlife, but it will also improve the potential for people to be more successful on any Alzheimer’s drug they may have to take later in life since individuals who take those drugs are less likely to benefit from those drugs if their underlying brain health is already impaired.”

For additional insights from Drs. Dolatshahi and Raji, watch the video below.

Researchers discuss new MRI and PET study findings that show a link between higher visceral abdominal fat and early development of Alzheimer's disease.

Emerging MRI and PET Research Reveals Link Between Visceral Abdominal Fat and Early Signs of Alzheimer’s Disease

In a recent interview, Mahsa Dolatshahi, M.D., M.P.H., and Cyrus A. Raji, M.D., Ph.D., discussed MRI and PET study findings, presented at the Radiological Society of North America (RSNA) conference, that showed an association between higher amyloid PET tracer uptake in the precuneus cortex and a higher visceral to subcutaneous fat ratio.

Emerging MRI and PET Research Reveals Link Between Visceral Abdominal Fat and Early Signs of Alzheimer's Disease

Artificial intelligence (AI) is of course one of, if not the hottest topic at this year's 

, but how is all of the hype translating to clinical practice?

As exciting as new technology can be, actually using that technology requires a great deal of effort, especially for larger institutions that are faced with training dozens of radiology staff. 

User education is a key component to adoption and uptake, according to Nina Kottler, MD, MS, associate chief medical officer of clinical artificial intelligence at Radiology Partners. Dr. Kottler spoke with 

 at RSNA 2023, where she reflected on Radiology Partners hitting (and recently surpassing) an impressive milestone: utilizing clinical AI in more than 20 million patient exams. None of that would be possible without purposeful training programs to make sure that radiology end-users are comfortable with the new technology and understand the key benefits of use. 

Dr. Kottler, who is also an associate fellow at Stanford University's Center for Artificial Intelligence in Medicine & Imaging (AIMI), also spoke about what she has observed in terms of the affect that AI is having on radiology workflows. 

Watch the interview below for additional insights on AI. 

Nina Kottler, MD, MS, of Radiology Partners, discusses the importance of user education to improve uptake of AI technology and improve ROI. 

Nina Kottler, MD, MS on AI Adoption in Radiology

Click here for more coverage of RSNA 2023.

Dr. Kottler sat down with Diagnostic Imaging at RSNA 2023 to discuss AI imaging milestones and the potential impact of AI on workflows in radiology. 

Nina Kottler, MD, MS on Adoption and Impact of AI in Radiology

Radiology experts discuss the current knowledge and use of PSMA-PET screening among colleagues, as well as unmet needs.

Current Use of PSMA-PET Scans for Prostate Cancer

 Do you think that PSMA-PET is already there or eventually will be the standard of care for patients with prostate cancer? And if it’s not, are we just on the horizon of it? What are your thoughts, Dr Sohi?

 It’s a great question. In the past year, I’ve had numerous discussions with urologists, medical, and radiation oncologists. I would say the consensus statement is that we’re almost there. We’re almost there because I’m very encouraged to see that our colleagues in urology and radiation oncology have embraced PSMA-PET imaging. We’re seeing a lot more utilization of this modality. We’re still seeing some sites that are doing CT and bone scan. It’s a habit. It’s a process that has been in place for many years, and you cannot expect that practice to change as quickly as we’d like.

There’s a practical matter that not every site has access to a PET-CT? So, especially in rural communities, you have a CT scanner. You may have a spec machine for bone scan, but you may not have access to PET-CT. Maybe they get a mobile PET-CT coming in once a week, once a month, and they have so many patients that they cannot get everybody on the schedule. We have to look at those scenarios. But beyond that, when available, I think we’re seeing it being utilized with greater frequency. To answer your question, I think we’re almost there. I can’t say we’re here today, but I think we’re very close. What have you seen in your practice, because you obviously have extensive experience with this modality? And you’re seeing these patients with greater frequency.

 Absolutely. First of all I would 100% agree with you that there’s still some work to be done. But...the standard of care has been set, or societies are saying it. Nonradiology societies are saying it. But in my own practice, yeah, I think we’re still not getting these patients in front or this tracer to the patients we need.

And it’s multifactorial. I can’t get into all the details of it. But we need to get there and we need to get there soon. You mentioned mobile PETs, and so here in Texas, you know, big states, small towns everywhere, big cities as well, but our small towns should not be left behind. We have a robust, mobile PET service in our practice that we partnered with one of our oncology practices. Those mobile PETs go around and get to cover a lot of miles between days and between weeks, and try to get our scanners out there. The key is to get the tracer, then, to that scanner as well. And are we working with ready pharmacies to make sure that’s available to our patients?

I’ll give you my thoughts on this last question, and then you can add on. There’s always a question [about] unmet needs and clinical challenges. We’re both touching on it a little bit about accessibility and availability and things like that. I think one...unmet need is enough trials and data to know, what does all this mean? I’d hate for patients to be upstaged by this great modality, this great tracer, and then not be offered the same conventional treatments they were receiving before. I think our urologist oncologists are clearly aware of this. It’s not going to happen overnight, but I think with time and the more utilization of this—we’re all learning this, right? We’re all using it as best as we can and offering the best information and interpretation of these scans. But I’m sure you’re the same way—I learned from my clinical colleagues when I read their clinical note, or how they’re using our study, and how the patient responded to certain treatments, and how our PET scan [is used]. I think you and I are just going to be absorbing this new data and information. But the unmet need to me is still the information that’s all coming from this scan. How are they going to apply to our patient population? Clearly, we need our patients staged initially. But once that happens and treatment starts, and that’s where we are, because we’re just starting to roll out this tracer. As we go forward, what’s going to change about that? So those are my thoughts. Do you have anything to [say about] what you feel is maybe an unmet need, or something to look to the future before we end here, Dr Sohi?

 Yes, absolutely, Dr Oza. Fortunately, we have plenty of data, and growing, given the fact that this modality has been utilized in Europe and Australia for multiple years. Of course, we always are looking for more data and more up-to-date information. But the good news is that we do have some perspective here, going back several years with our European colleagues.

One of the unmet needs and clinical challenges that I see is the need to continuously educate and collaborate with our referring physicians. Make them aware.... A urologist that I was speaking with, they were not aware that this modality was actually being offered locally to their location. Awareness of this tracer in the local vicinity is important. Equally important is educating and collaborating with our colleagues, the radiologists, the nuclear medicine physicians who...may be in a practice where [they’re] doing PETs once a month, once a week.... They might be reading 2 or 3 scans per month. There’s a lot of work yet to be done in educating our peers with regard to how to read [scans] and how to clean the data from this modality. We all know about the artifacts, right? That can be an update and all that stuff. That’s still a work in progress. I think we’re making a lot of headway. But there’s still a lot of work to be done in educating our peers so they can, then, impact the patient care in a most positive way.

 Absolutely, I would absolutely agree with that. Well, I want to thank you very much, Dr Sohi, for your input, your insights, discussion. I always learn something when I speak to people like you. And today I definitely learned some things. So, I want to thank you, and for our audience, we hope you found this review discussion informative.

Transcript is AI-generated and edited for clarity and readability.

Imaging experts compare gallium-based agents to non–gallium-based agents for prostate cancer screening.

Comparing Agents in Prostate Screening

 We’re getting into physics a little bit. But those are the 2 differences there. While we’re on the physics topic, [regarding half-life]. We know F-18–based ones are about 110 minutes, right? Generally, gallium-68 is similar to the 68. It’s about 68 hours; easy to remember that way. That plays into how we can use it. Generally, an hour half-life is a pretty good tracer. We’re not talking [about] our cyclotron-produced 10-minute, 2-minute, 5-minute tracers, which totally decay fast. You just need to be right next to a cyclotron. Good...clinical application of both, in that sense. Do you see any differences? Have you noticed, or have you seen anywhere in the literature any differences, generally speaking, about their sensitivity or specificity, or in certain, let’s say, organs or systems in the body, one has an advantage over the other?

 Just to clarify, the gallium-68 has a half-life of 68 minutes, like you mentioned. With regard to bio distribution, for example, both tracers have a similar bio distribution profile with prominent updates in the salivary glands, liver, spleen, bowel, and bladder. The one area where you may see some slight difference, and it can be impactful down the road, especially in patients with metastatic disease, is the liver because F-18 has a better ability, has some compatibility. You may see higher background hepatic uptake on normal setting, on a normal bio distribution compared with gallium-68. So, something to keep in mind. Beyond that, they have a similar bio distribution profile. With regard to image quality resolution, I think, theoretically, there is a slight benefit to F-18, because it has better profile with regard to the imaging characteristics. However, I think, on a practical level, it really depends on the camera type, imaging equipment you have at your disposal, and the reconstruction parameters that you are utilizing to reconstruct the images. I think those play a large role. And what kind of image quality you’re acquiring.

 Absolutely. I agree. I think there are so many variabilities. When people talk about sensitivity and specificity, there is just so much you can do between cameras and how you set your camera up, the uptake time. How many minutes per bed step you’re doing, as you mentioned, reconstruction, all that factors in. There are a lot of variables that need to be taken into consideration. To your point about the liver activity, I struggle with that at times, reading these scans I have to, I call it “detoasting” or deintensifying the liver so much on the F-18s to see through that activity or that intensity. I’ve seen just anecdotally, I’ve called lesions that are on CT. Both of us being both radiologists, we can see on those CTs, we’re looking for the hyperattenuating, low-attenuation lesions on the CT and seeing if there’s a correlate on the PET images. I’m sure you’ve noticed that when you deintensify the liver, all of a sudden these lesions you can see on CT come back to the PET image, and that’s when you say, Well, it’s not cold. It’s not absent, as I’d expect with a cyst or other, benign lesions. In fact, it has a low-level uptake. And those lesions I have recommended further evaluation with MRI or something else that we can see, and with the gallium I’ve done that last. But certainly I’ve seen more of that 18, and I’ve been recommending, especially when I can’t characterize those lesions as benign lesions. So that’s interesting. Do you have any experience or thoughts on gallium vs F-18 on this uptake in bone lesions? Knowing prostate cancer goes to nodal match, and obviously bone is a very common place for metastases. Have you any thoughts or read any literature, or have any specific experience on bone lesions between the 2 specific tracers?

 Yes, yes, we have. In our practice we have noticed that. And I think there are some data out there from literature with regard to a higher instance of nonspecific bone uptake with F-18 compared with gallium 68. Because F-18 has a higher predisposition, predilection to bone.... From a practical and a patient care perspective it can be a challenge because we know very well that prostate carcinoma tends to metastasize to the bones. If you’re seeing any areas of increased uptake in the bones, you then have to resolve and figure out whether these lesions are benign, nonspecific, or represent true metastatic disease, because that distinction will have true, real implications in patient care. For example, on an anecdotal level, I was having a discussion with a urologist yesterday, and the question came up, What do you do in a newly diagnosed, prostate [cancer] patient with disease in the prostate gland, and...some areas of focal uptake in the bones? Now, do we still offer them prostatectomy? Or are they now sent to a different treatment paradigm? Frankly, I’d love to see what your experience has been and what you’ve seen in your practice with regard to this particular topic.

 Sure. So, having seen more F-18, I definitely see these. Some people call them unidentified or unsure bone uptake, UBUs, and we’re seeing those on scans. I try my best to look at those CT images to see, is it fibrous dysplasia, is it a fracture...something like that? But when we’re talking about the rib, which can be 4 or 5 mm thick, and you’re trying to find out if this has any ground-glass attenuation and say, Yeah, this is definitely fibrous dysplasia. That’s tough. Right? Because like you said, this is where the urologist wants to know, the patient needs to know for care if they’ve got a single lesion in the prostate, [or] there are multiple lesions on the prostate and no nodes. And you have this one rib lesion that’s either gonna be...metastatic disease or nothing with fibrous dysplasia. There really isn’t even an imaging study I can recommend for some of those findings because even if I’m reading the CT or my colleagues are reading the CT, they’re not gonna hammer and say when they had this hot spot on a PET scan, which they’ve already all accepted, that we [have] the answer for cancer, not cancer. And they’re gonna say, yeah, this is probably just fibrous dysplasia, fibrous cortical defect or ossifying, nonossifying fiber. All those other terms [and] all these other lesions we usually see. So absolutely, I’ve seen it from the gallium studies. I’ve not seen as many, but that’s mostly anecdotal, and I’ve read the same study you have that’s shown that, as you mentioned, F-18 being a sodium fluoride PET bone scans, right? We used to do those all the time, and I don’t think I’ve seen that in a handful of years. Those false positives are certainly out there, and also to mention what to do with this increased sensitivity of finding these lesions. All of our urologists, and this is sort of getting ahead of the topic here, but the urologists know the treatment protocols, the trials, the research, all the data are based on conventional imaging, diagnosing these metastases. We have these patients who originally were intermediate stage and don’t have any lesions. And all of a sudden they’re intermediate stage, and we’re seeing more lesions, upstaging them. Should they still qualify for the additional treatments, or now we put them in a different pathway? Now it’s not something you and I can figure out here, and you may have more knowledge about treatment than I do. I’m not going to go there, but I think that’s one of the challenges that we face with this new tracer, and how we’re staging and restaging, PET-CT. Would you agree with that? Is that something you’re seeing as well?

 Yes, absolutely. Just to add to your comment about how to resolve these areas of nonspecific bone uptake, you’d mentioned, what do you do next? That’s a real diagnostic dilemma, because if I’m seeing something on that without a definite anatomic correlate, I don’t really have good options with regard to a second, a follow imaging study, x-ray, CT, and MRI. They may or may not show anything if I’m not seeing anything on the CT portion of my PET. The second aspect to that is the time frame. Getting patients in for a follow-up imaging study is not often straightforward. You have to, depending on the modality you’re looking at, for example, MRI, you have to get authorization. There’s a time gap between when you order the study and when the patient actually is able to get into the scanner and get the follow-up. There’s that time lapse as well that we have to think about. Patients in the meantime are suffering from genuine and reasonable anxiety and stress about what that planning on the scan means. We have to think about that aspect as well. Utilizing a modality that has lower incidence of nonspecific activity is always preferred.

 Yeah, absolutely. I think we can. We get behind that for sure.

Types of PSMA-PET Scans in Prostate Cancer

 So, we both mentioned PSMA-PET [prostate-specific membrane antigen-positron emission tomography]. You and I both know there are 2 radioisotopes bound to different agents, PSMA [and] amino acid, among other things. Can you touch on what 2 different radionuclides are available for PSMA-PET, just generally? Then we can talk a little bit more specifically about advantages and disadvantages.

 Absolutely. The first tracer that comes to mind is gallium-68 PSMA. That’s the one that has been utilized in Australia and Europe for the past about 7-plus years. Our first FDA-approved tracer in the US was gallium-68 PSMA, which was developed by [University of California San Francisco] and [University of California, Los Angeles] back in December 2020. As the name suggests, it’s a gallium-based imaging agent. The second PSMA agent that’s available is F-18, or fluorine-18 PSMA, which was approved, I believe, in May 2021. That’s a newer agent, and now both are in utilization and practice.

That’s interesting because on our side, where we are, in a big city, Dallas, we saw the F-18 agent show up first, and then we saw the gallium-68. You’re telling me that, in Europe and the rest of Australia, it’s been around for almost 7 years. It’s interesting how things work out about availability in big cities like this. But I’m hoping we’re seeing more of a balance and that we’re looking at both tracers. We have enough data to look at what’s best for our patients, what subset of patients, what scenarios, and things like that. Let’s just talk first about how each one is made. How are they produced? Is there a difference between the gallium and the fluorinated PSMA agent?

 Yes, and again, just to complete the loop from the prior topic, I think you’ve mentioned that you’ve seen higher utilization, or greater utilization, or earlier adoption of F-18 compared with gallium. I think part of the reason is that the first tracer, although it was gallium-68 that was approved in the US, that was, technically available to anybody, but really in practical terms, was available to patients who could travel to those institutions.

Then, of course, everything was approved, and then that became available. Maybe that’s the reason why we had the approval of a tracer, but it was not highly, widely available. I think with regard to how they’re produced, the gallium-68 is a generator-produced isotope, and F-18 is produced by cyclotron. Do you want to go into a little detail? How about you? Go into some detail about what the difference between a generator and a cyclotron is.

 Sure, [with] a cyclotron, you’ve got to have some space. It’s very highly radioactive, [with a radioactive area of] what used to be a football field. But now they’re smaller than that. But they’re very high-radiation areas. They need very big regions of shielding, concrete, and lead, and are very expensive. And that’s where our fluorinated agents are coming from. For our mainstay F-18 PET-CT, we do it for every other malignancy. A generator is something that you have, a parent, if you will. Then it decays to a, we call it a daughter in the nuclear medicine world. A generator will make that as it decays, [and] you can pull off what you’re trying to produce. In this case, it’s [such a] smaller piece of equipment. It does have its own half-life and decays. But once you have that generator, you can produce that isotope locally, fairly easily, efficiently. And you can distribute those generators to smaller areas. You can’t move a cyclotron and say, “Hey, I want this cyclotron in my small town right now,” but you can move generators, or you can have a setup where the generators are closer to these smaller towns.

Experts highlight gallium-based and PyL PSMA-PET scans for use in prostate cancer, commenting on approvals as well as how the agents are made.

Types of PSMA-PET Scans in Prostate Cancer 

 You know what the SNMMI [Society of Nuclear Medicine and Molecular Imaging] have come out with some guidelines of when to do these studies now in my world [and] in your world. We’re both practicing in clinical practice and some academic. But we have to go by guidelines, because in the end of the day. Insurance companies are going to rely on that for approval. So why don’t we talk about the guidelines and the indications. Let’s [take a] deep dive into these guidelines and [discuss] when a PSMA PET-CT may be indicated according to our society.

 Interesting question, because in the past several months, at the annual AUA [American Urological Association] meeting in June in Chicago, the NCCN [National Comprehensive Cancer Network] guidelines, the Society of Nuclear Medicine and Medical Imaging guidelines all now have come out with statements that you can replace conventional imaging, CT and bone scan, with PSMA PET for initial staging and researching purposes. So, in other words, now we have guidelines that have been updated as recently as this year, given the benefits of PSMA PET, given the clarity of diagnosis of PSMA PET. And now you’re able to utilize this modality in lieu of the previously mentioned imaging modalities. How has that impacted your clinical practice? And what are you using with regard to guidelines?

 Absolutely, I would [use it]. It’s busy, all of a sudden these scans are being done on these patients who otherwise didn’t have access to this PSMA-PET. [The number of ordered] bone scans have definitely gone down as far as I can see in our practice, the number of studies being ordered. We still use it for other cancers or troubleshooting lesions, but, certainly, I have seen less bone scans being ordered. On the CT side, it’s hard for us to gauge because I think CT is so prevalent that it’s hard. Maybe there’s a blip, but I don’t know if that’s a trend, or just a small little change from month to month. But absolutely, PSMA, we have folks, and we’ll talk a little bit about patient awareness about this.… There’s always a subset of patients who are very aware of their care, and what’s out there, and what they can ask for, what’s the best test or best treatment, and they like to look that up. And I think doctors, on the whole, like patients like that coming to them with information well thought out and asking about their care. And we’re seeing a little bit of that push from our oncologists, saying, “Yeah, our patients are asking for this. Can we get it?” So availability and distribution of the tracer is different. We’ll touch on the gallium vs the F 18–based tracers or radio isotopes. We can touch on that. But I’ve definitely seen it. There’s no doubt about it that almost it used to be 1 day a week, because [only the pharmacy can] deliver it, and a few months ago [it became] 2 or 3 days a week, and now it’s every day we’re seeing PSMA PET-CTs being used, and not just for staging, but restaging, but even after treatment, like we’re seeing in what we experience in the lymphoma world, where [when they’re] staging, they’ll give a few doses, or maybe 1 or 2 doses, and…if that those lymph nodes improve after 1 or 2 doses, [it’s] a great positive prognostic indicator for this patient. So we’re seeing it very early as long as insurance is approving it. Or if they’re on a trial, we’re seeing frequent PSMA PET-CTs being ordered. I’m sure you’re seeing the same thing.

Yes, [that’s a] really interesting observation and perspective. Have you seen the utilization of PSMA PET vary by risk group?

 I have. When we dictate, we get all the clinical information. And obviously I’ve not seen any [with] Gleason [scores of] 6 or less, very low-risk patients. So we’re seeing the higher-risk patients. I’ve seen more Gleason 9s than I’ve ever seen ordered on a bone scan. We’re seeing those patients show up more often. And down to 7, I would say, we’re still seeing the [Gleason] 7s, Gleason 3 + 4, 4 + 3 [types of] 7s. [That’s what] we’re seeing. So I’d like to see more of that, because I think the guidelines say that we can do it in those patients. And in the past we would not see much disease on there. But, certainly, we’re seeing that in the lower risk, and maybe that’s something in the future [where] we may see even the lower risk [patients], [the] very low risk, low-risk patients with Gleason 6 [or lower scores for whom] this PSMA still could be helpful. We don’t have the data. It would be interesting, because I’m not seeing that. Are you seeing patients in that in that subgroup being imaged yet?

No, I think not as of now. I think the guidelines and the appropriateness criteria currently is, I believe, unfair about intermediate risk and higher. But do I think that may change? I think the answer is probably yes. Especially as we get more data on PSMA imaging at an earlier time point in the patient’s journey. Perhaps as our technology improves with regard to resolution, so [it’s] definitely a space to watch.

Two experts review SNMMI (Society of Nuclear Medicine and Molecular Imaging) guidelines for use of PSMA PET scans in prostate cancer detection, as well as awareness about this new modality within the patient community.

Molecular Imaging

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