Role of non-contrast CT component of prostate-specific membrane antigen PET/CT scan in the detection of peripheral zone prostate cancer.

OBJECTIVE: The aim of this study was to look for feasibility of non-contrast CT (NCCT) in detecting peripheral zone prostate cancer (PCa). METHODS: A retrospective analysis included 50 biopsy-proven PCa patients between April 2019 and March 2022 who underwent staging whole body prostate-specific membrane antigen (PSMA)/CT prior to treatment. The control subjects were 50 randomly selected adult male patients who underwent PET/CT for non-prostate malignancy during the same time period. Two readers independently calculated the Hounsfield unit (HU) of normal peripheral zone, central zone, and corresponding PSMA avid focus in cases. RESULTS: No significant difference was seen in the mean HU value of normal peripheral zone between cases and controls. Significant difference in the mean HU was seen between the PSMA avid focus in cases (40.1 ± 6.2) and normal peripheral zone of cases (28.2 ± 7.0) and controls (27.7 ± 5.8). No significant difference was found between the mean HU values of high-grade PCa and non-high-grade PCa. Receiver operating characteristic (ROC) curve analysis revealed a mean HU cut-off of ≥35 for detecting PCa with a sensitivity and specificity of 86% and 90%, respectively, between cases and controls (AUC 0.88). CONCLUSION: Detection of clinically significant PCa is possible on routinely performed NCCT scans. Radiologists should routinely look for and convey these findings to facilitate further work-up and early detection of PCa. ADVANCES IN KNOWLEDGE: Our study adds to the knowledge that NCCT scans performed for unrelated indications can serve as a screening tool for clinically significant PCa.

Ga-68 Prostate-Specific Membrane Antigen-HBED-CC Positron Emission Tomography/Computed Tomography in Anaplastic Thyroid Carcinoma.

Purpose: Anaplastic thyroid carcinoma (ATC) is the most aggressive thyroid cancer and there is no established treatment that works well. The study was conducted to see prostate-specific membrane antigen (PSMA) expression in ATC as a stepping stone to study its role in potential theranostics. Materials and Methods: Pathologically proven ATC patients were prospectively included in this study. Ga-68-PSMA positron emission tomography/computed tomography (PET/CT) was done to look for PSMA expression in local and distant sites 45-60 mins after injecting 2-3mCi of tracer. Results: Twenty patients were enrolled in this study. Nodal metastases were seen in all patients, while distant metastases were seen in 17/20. The mean SUVmax of primary lesion was 6.72 ± 4.6. Mean SUVmax of node and lung lesions was 5.7 ± 5.6 and 2.9 ± 1.98, respectively. Mean SUVmax of liver, mediastinum, and parotid gland was 5.95 ± 3.03, 1.54 ± 0.68, and 9.03 ± 3.75, respectively. Mean Tumor to background ratio (liver = TBRl; mediastinum = TBRm; parotid = TBRp) were 1.21, 4.49 and 0.78, respectively. Conclusion: ATC showed variable PSMA expression on Ga-68-PSMA-PET/CT and this attribute may be potentially useful in ATC theranostics.

PET/CT in Evaluation of Low Backache Due to Sacral Nerve Root Involvement: Inflammatory and Malignant Involvement.

Low back pain with radiation to lower limbs is due to nerve root impingement or involvement in most cases. F-FDG PET/CT has shown sacral nerve root involvement in several peripheral nerve pathologies, including neurolymphomatosis, peripheral nerve sheath tumor, and plexopathies. We present 2 cases of a low back pain with ulcerative colitis and metastatic neuroendocrine tumor who underwent F-FDG PET/CT and Ga-DOTANOC PET/CT, respectively. PET/CT can be used as an adjunct tool to evaluate sacral nerve root involvement to look for malignant or inflammatory nerve involvement.

68Ga-Prostate-Specific Membrane Antigen PET/CT in Triple-Negative Breast Cancer.

The prostate-specific membrane antigen (PSMA) is a transmembrane protein with elevated expression in prostate cancer cells. Breast cancer also shows PSMA expression. We present the case of a 30-year-old woman with triple-negative bilateral breast carcinoma who underwent bilateral mastectomy, chemotherapy, and radiotherapy. She developed a left chest wall and liver recurrence after primary therapy. Her recurrent disease was also triple-negative. In view of the known poor prognosis and very limited therapeutic options, we performed Ga-PSMA PET/CT scan to explore the possibility of PSMA-based therapy as a future option after exhausting standard-of-care treatments.