ABSTRACT
Prostate cancer is the second most common malignancy in men worldwide, with a good prognosis when is detected and treated in early stages, but, when it presents progression to castration-resistant metastatic prostate cancer, most of the cases will have bone metastasis, decreasing the quality of life and life expectancy. For the evaluation of the disease in the routinary clinical practice, 68Ga-PSMA PET/CT, among others is a valuable tool for the evaluation of the disease extension. 68Ga-PSMA PET/CT detects the presence of PSMA receptor in the tumoral tissue, but also has physiologic uptake in certain organs, such as liver, spleen, intestine, kidneys, lacrimal and salivary glands. Total or partial absence of uptake in those organs is rare and may be due to a high metastatic tumor burden, a phenomenon originally described in bone scintigraphy as super scan. We describe a case series of seven patients with prostate cancer from the National Institute of Cancerology in Colombia, in which a super scan pattern was found in the evaluation with 68Ga-PSMA PET/CT, proposing the suppression of uptake in the intestine, liver, spleen, lacrimal and salivary glands as the main criteria for its definition, and showing that renal uptake persists in most cases, considering that, unlike the super scan in conventional bone scintigraphy, this is not a criterion necessary for its definition in the study with 68Ga-PSMA.
ABSTRACT
PSMA expression occurs in epithelial cells in both normal and hyperplastic prostates. In adenocarcinoma, it is present in greater intensity, especially in the more aggressive ones. This made it possible to develop diagnostic tools with greater specificity for detecting prostate cancer metastases like the 68Ga-PSMA PET/CT. Several benign neoplasms with increased marker uptake have been described in the literature. Such false-positives are usually associated with soft tissue injuries, abnormal vascular proliferation, neurogenic injuries, thymomas and adenomas. In the present work we present a case report that exemplifies the above.
ABSTRACT
PURPOSE: To compare the diagnostic performance of 68Ga-PSMA PET/TC with PRI-MUS (prostate risk identification using micro-ultrasound) in the primary diagnosis of prostate cancer (PCa). METHODS: From September till December 2018, we prospectively enrolled 25 candidates to 68Ga-PSMA PET/TRUS (transrectal ultrasound) fusion biopsy and compared them with PRI-MUS. This included patients with persistently elevated PSA and/or PHI (prostate health index) suspicious for PCa, negative digital rectal examination, with either negative or contraindication to mpMRI, and at least one negative biopsy. The diagnostic performance of the two modalities was calculated based on pathology results. RESULTS: Overall, 20 patients were addressed to 68Ga-PSMA PET/TRUS fusion biopsy. Mean SUVmax and SUVratio for PCa lesions resulted significantly higher than in benign lesions (p = 0.041 and 0.011, respectively). Using optimal cut-off points, 68Ga-PSMA PET/CT demonstrated an overall accuracy of 83% for SUVmax ≥ 5.4 and 94% for SUVratio ≥ 2.2 in the detection of clinically significant PCa (GS ≥ 7). On counterpart, PRI-MUS results were: score 3 in nine patients (45%), score 4 in ten patients (50%), and one patient with score 5. PRI-MUS score 4 and 5 demonstrated an overall accuracy of 61% in detecting clinically significant PCa. CONCLUSION: In this highly-selected patient population, in comparison to PRI-MUS, 68Ga-PSMA PET/CT shows a higher diagnostic performance.