A pictorial view on false positive findings of 68Ga-PSMA-11 PET/CT and their prognostic value in patients with prostate carcinoma after radical prostatectomy and undetectable PSA values.
Z. Dancheva, Sophiya Chausheva, Tanya Stoeva, M. Dyankova, T. Yordanova, B. Chaushev, Rostislav Marinov, Viktor Nikolov, Pavel Abushev, Georgi Todorov, Eleonora Dimitrova, A. Klisarova, Deyan Anakievski
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引用次数: 0
Abstract
OBJECTIVE
Recently, gallium-68-prostate-specific membrane antigen-11 (68Ga-PSMA-11) positron emission tomography/computed tomography (PET/CT) has become a key imaging method in prostate carcinoma staging and biochemical progression, with varying sensitivities in different studies (from 40% to 80%). After four years of experience with 68Ga-PSMA-11 PET/CT, we found that it is possible to detect lesions with increased PSMA expression in patients with undetectable prostate specific antigen (PSA) levels after radical prostatectomy. The key questions we wanted to answer were as follows: if those lesions were malignant and could the early detection of those malignant lesions have a role in patient management? We aimed to identify and follow up PSMA-positive findings for a period of 4 years in patients with prostate cancer after radical prostatectomy and undetectable PSA values at the time of the examination. We also explored false-positive lesions in detail.
SUBJECTS AND METHODS
The study included all patients who underwent radical prostatectomy and had undetectable PSA values <0.05ng/mL and who underwent 68Ga-PSMA-11 PET/CT between July 2019 and December 2019. We performed 220 studies and found 40 patients with these characteristics; these patients were included in this study. All of them were followed up until July 2023. Any finding with increased radiopharmaceutical accumulation above the background activity in the respective area was considered a false positive. Prostate-specific membrane antigen accumulation in established lesions was assessed semiquantitatively by the maximum standardized uptake value (SUVmax) and qualitatively by the four-point visual scale proposed in the E-PSMA recommendations.
RESULTS
We found 15/40 (37.5%) patients with PSMA-positive findings. These were predominantly bone changes without a corresponding CT abnormality or discrete cystic or osteoblastic lesions with above-background increased PSMA expression. The mean SUVmax of these nonspecific lesions was 3.02 (SD 2.86). After 3.5-4 years of follow-up, biochemical progression was found in only two of the patients.The great sensitivity of the method nowadays is a powerful engine for the development of new therapeutic options. On the other side, the lower specificity due to false positive findings, if misinterpreted, might lead to switching to a higher stage, with the planned radical treatment replaced by palliative treatment.
CONCLUSION
The presence of 68Ga-PSMA-11 PET/CT-positive findings in patients after radical prostatectomy and an undetectable PSA had a low predictive value for future progression. The interpretation of 68Ga-PSMA-11 PET/CT should always include a complex assessment of the clinical setting-the risk group, PSA value and degree of PSMA accumulation in the lesions. In these situations, further clarification of PSMA-positive findings is appropriate before deciding to change treatment.
期刊介绍:
The Hellenic Journal of Nuclear Medicine published by the Hellenic Society of
Nuclear Medicine in Thessaloniki, aims to contribute to research, to education and
cover the scientific and professional interests of physicians, in the field of nuclear
medicine and in medicine in general. The journal may publish papers of nuclear
medicine and also papers that refer to related subjects as dosimetry, computer science,
targeting of gene expression, radioimmunoassay, radiation protection, biology, cell
trafficking, related historical brief reviews and other related subjects. Original papers
are preferred. The journal may after special agreement publish supplements covering
important subjects, dully reviewed and subscripted separately.