ARRS Annual Meeting: Significance of Nonspecific 18F DCFPyL Rib Uptake on PET/CT in Prostate Cancer Patients

San Diego, CA | May 1, 2025—According to the Cum Laude Award-Winning Online Poster presented during the 2025 ARRS Annual Meeting, evaluating increased rib uptake on 18F-DCFPyL PET/CT may be challenging, even resulting in false-positive findings.

“In patients without osseous metastasis, the uptake is often low (less than the mean liver SUV), stable, and likely represents benign etiologies, such as fibrous dysplasia, fibrous cortical defect, traumatic fractures, and hemangiomas. Thus, further evaluation is usually not required,” said presenter Aisha Alam, DO, from the Icahn School of Medicine at Mount Sinai in New York, NY.

Dr. Alam and her all-Icahn School team performed a retrospective review of patients with prostate cancer who underwent PET/CT scans with radiotracer fluorine-18 2-(3-{1-carboxy-5-[(6-18F]fluoro-pyridine-3-carbonyl)-amino]-pentyl}-ureido)-pentanedioic acid (18F-DCFPyL) at a single academic center from June 2021 to April 2024. Alam and colleagues’ EHR search identified patients with increased radiotracer rib uptake. The team excluded patients with imaged evidence of osseous metastasis at other sites or with CT suggestive of alternate diagnoses, then analyzed Gleason scores, most recent serum PSA levels, maximum standardized uptake values (SUVmax) in the rib foci, and mean liver SUV (Fig. 1). Finally, for confirmation of benignity, follow-up evaluation included stability on 18F-DCFPyL PET/CT and/or imaging modalities such as CT, bone scan, or MRI.

With 204 total 18F-DCFPyL PET/CT scans showing solitary or multiple foci of increased rib uptake without CT correlation and imaging evidence of osseous metastatic disease, the mean age was 68 years old, mean Gleason score was 7, mean PSA was 7.9 ng/mL (range: undetectable–50.2 ng/mL), mean SUVmax for rib uptake was 3.8 (range: 1.4–9.8), and mean liver SUV was 5.7 (range: 2.7–10.9).

“Of the 204 scans,” Alam noted, “31 studies belonged to 13 patients who underwent follow-up 18F-DCFPyL PET/CT for restaging.”

For patients with redemonstrated rib uptake, mean SUVmax was 3.5 and mean SUVmax percent change on subsequent scans was 15.1% (range: 0–46.4%). And for patients with multiple PET/CT scans, the SUVmax for each foci of rib uptake was less than the mean liver SUV (mean: 6.1, range: 4.0–8.8). Of the 23 single-scan PET/CT patients who had a rib uptake greater than the liver mean, 14 of those had a PSA less than 10 ng/mL.

“Larger studies evaluating similar findings with histologic correlation and follow-up imaging are needed to improve diagnostic certainty,” added Alam et al.

North America’s first radiological society, the American Roentgen Ray Society (ARRS) remains dedicated to the advancement of medicine through the profession of medical imaging and its allied sciences. An international forum for progress in radiology since the discovery of the x-ray, ARRS maintains its mission of improving health through a community committed to advancing knowledge and skills with the ARRS Annual Meeting, two radiology journals—American Journal of Roentgenology (AJR) and Roentgen Ray Review (R3)—InPractice magazine, ARRS Symposia, free-access multimedia from our Global Partner Societies, as well as awarding scholarships via The Roentgen Fund®.

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