For the detection of clinically significant prostate cancer (csPCa), emerging research showed the use of ¹⁸F-PSMA-1007 positron emission tomography/computed tomography (PET/CT) accurately differentiated 65 percent of PI-RADS 3 lesions.

That is one of the findings from a new prospective study, recently published in Radiology, which examined the use of ¹⁸F-PSMA-1007 PET/CT in 75 men (median age of 67) with elevated prostate-specific antigen (PSA) levels (median 7 ng/mL) who previously had multiparametric magnetic resonance imaging (mpMRI) exams. Out of 102 detected lesions, 68 were PI-RADS 3 or higher lesions, according to the study.

On a per-participant basis, the researchers found that ¹⁸F-PSMA-1007 PET/CT provided a 91 percent sensitivity rate in comparison to 95 percent for mpMRI in detecting csPCa. The study authors also noted that 18F-PSMA-1007 PET/CT had a 62 percent specificity rate in contrast to 45 percent for mpMRI.

Here one can see pre-biopsy imaging, including mpMRI and ¹⁸F-PSMA-1007 PET/CT scans, revealing clinically significant prostate cancer (csPCa) with a PI-RADS 3 lesion. A recent prospective study found that ¹⁸F-PSMA-1007 PET/CT had a 91 percent sensitivity rate for diagnosing csPCa and a 93 percent negative predictive value (NPV) for ruling out csPCa in PI-RADS 3 lesions. (Images courtesy of Radiology.)

For PI-RADS 3 lesions, the researchers noted a 93 percent negative predictive value (NPV) for ¹⁸F-PSMA-1007 PET/CT as use of the agent led to upgrading or downgrading of these lesions in 17 of 26 study participants (65 percent).

“ … For PI-RADS 3 lesions, where radiologists are uncertain about the presence of PCa, ¹⁸F-PSMA-1007 PET/CT seemed useful, as PET was able to help correctly distinguish between tumor tissue and benign disease in 65% of lesions due to a particularly high NPV of more than 90%,” wrote lead study author Bastiaan M. Prive, M.D., Ph.D., who is affiliated with the Department of Medical Imaging and Nuclear Medicine with the Radboud University Medical Center at the Radboud Institute for Health Sciences in Nijmegen, the Netherlands, and colleagues.

The researchers also noted key attributes with ¹⁸F-PSMA-1007 PET/CT that may make it a viable alternative to other PET/CT imaging agents.

“In this setting, fluorine 18 (¹⁸F) PSMA-1007, a novel radiolabeled PSMA ligand, is particularly attractive due to its low renal excretion, improving the visibility of PSMA-positive foci in proximity to the urinary tract (i.e., the prostate) compared with other PSMA tracers. Moreover, the lower positron energy of ¹⁸F offers higher resolution than gallium 68 (⁶⁸Ga)–labeled compounds (e.g., Ga-PSMA-11),” added Prive and colleagues.

In an accompanying editorial, Baris Turkbey, M.D., emphasized the adjunctive possibilities of ¹⁸F-PSMA-1007 PET/CT in mitigating the challenges of indeterminate PI-RADS 3 lesions.

“The study by Prive et al confirms the potential of 18F-PSMA-1007 PET/CT as a tool that is complementary to mpMRI in the diagnosis of PCa. While demonstrating good sensitivity and moderate specificity, this hybrid approach notably excels in ruling out clinically significant PCa in PI-RADS 3 lesions,” said Dr. Turkbey, a senior clinician with the Molecular Imaging Branch of the National Cancer Institute at the National Institutes of Health (NIH).

(Editor’s note: For related content, see “PET/CT or mpMRI: Which is Better for Detecting Biochemical Recurrence of Prostate Cancer?,” “Study: PET/MRI May Prevent Up to 83 Percent of Unnecessary Biopsies in Men with PI-RADS 3 Lesions” and “New Research Evaluates PI_RADS Upgrading Rules in MRI Exams for Prostate Cancer.”)

In regard to study limitations, the authors noted inconsecutive patient enrollment, an underpowered sample size and possible confirmation bias due to awareness of mpMRI findings by the nuclear medicine physicians. The researchers also conceded that performance of the study at a MRI referral facility may limit extrapolation of the study findings to a broader population.

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