68Ga-PSMA-11 PET/CT Provides Benefit for Inconclusive Imaging

By Emily Menendez - Last Updated: August 18, 2022

Bone scintigraphy (BS) and computed tomography (CT) imaging processes are typically used as standard imaging recommendations for the primary staging of those with intermediate- and high-risk prostate cancer (PCa). A recent study shows that when these tests come back as inconclusive, 68Ga-PSMA-11 PET/CT can be useful in providing a conclusive diagnosis of equivocal lesions found in the bones or lymph nodes.

While BS and CT imaging tests are common prostate cancer staging identifiers, inconclusive results are not uncommon and can impact a patient’s decision regarding what treatment they will undergo. A 2015 study showed that out of 459 patients with prostate cancer, 13% were found to have inconclusive bone scans. Another study of 366 patients also saw 13% of the group have inconclusive bone scans. Sufficient data on how these inconclusive scans affect clinical practice have not yet been reported, nor have researchers reported on how this issue plays a role in the treatment decision-making process for patients.

Some patients that receive BS or CT imaging will have equivocal lesions or divergent findings, which can result in inconclusive disease staging. A study by Nalliah S and Zacho HD examined patients with newly diagnosed PCa who received inconclusive disease staging based on BS and CT imaging to determine the added value of 68Ga-PSMA-11 PET/CT post-imaging.

In this study, 76 patients were analyzed from January 2017 to December 2020. Out of the study population, there were 62 patients with 72 equivocal lesions and 14 with inconsistencies between BS and CT imaging. The study found that 61% of patients had equivocal lesions in the bones, while 17% has lesions in the regional lymph nodes. The value of 68Ga-PSMA-11 PET/CT was determined for each location of equivocal findings including bones, regional and nonregional lymph nodes, and other metastases.

68Ga-PSMA-11 PET/CT was found to provide a conclusive diagnosis and definite disease stage in 90% of the patients’ equivocal lesions, and found 32 other metastasis sites that were not visible through standard imaging in 25 patients as well.

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