Prediction of clinically significant prostate cancer by [68 Ga]Ga-PSMA-11 PET/CT: a potential tool for selecting patients for active surveillance.

PURPOSE: In our study, our aim was to investigate the role of [68 Ga]Ga-PSMA-11 PET /CT imaging in the diagnosis of clinically significant prostate cancer (csPCa) (ISUP GG 2 and higher) in patients initially diagnosed with ISUP GG 1 and 2 after prostate biopsy. MATERIALS AND METHODS: We retrospectively reviewed 147 patient records in whom [68 Ga]Ga-PSMA-11 PET/CT imaging was performed preoperatively. All patients were initially diagnosed with ISUP GG 1 and 2 PCa by biopsy. Final pathology reports were obtained after radical prostatectomy. The [68 Ga]Ga-PSMA-11 PET/CT images were evaluated to determine the PRIMARY score. Patients' mpMRI-PIRADS scores were also recorded when available and analyzed in correlation with the pathology results. RESULTS: For the 114 patients scored using PRIMARY, 19 out of 37 patients with scores of 1 and 2 (51%) were diagnosed with csPCa. Of the 77 patients with PRIMARY scores between 3 and 5, 64 (83%) had csPCa. Notably, every patient with a PRIMARY score of 5 had csPCa. PRIMARY scoring had a sensitivity of 77% and specificity of 58%, with a positive predictive value of 83%. A moderate correlation was observed between PRIMARY scores and ISUP GG (Rho = 0.54, p < 0.001). In contrast, the PIRADS score displayed a sensitivity and specificity of 86% and 25% respectively, with a positive predictive value of 68%. No substantial correlation was found between PIRADS and ISUP GG. Statistical analysis revealed a significant correlation between PRIMARY and ISUP GG (p < 0.001), but not between PIRADS and ISUP GG (p = 0.281). Comparatively, PRIMARY scoring was significantly more reliable than PIRADS scoring in identifying csPCa. CONCLUSION: [68 Ga]Ga-PSMA-11 PET/CT imaging is promising for distinguishing high-risk prostate cancer patients from those apt for active surveillance, potentially aiding in the identification of csPCa.

Evaluation of F-18 DOPA PET/CT in the detection of recurrent or metastatic medullary thyroid carcinoma: comparison with GA-68 DOTA-TATE PET/CT.

OBJECTIVE: PET imaging with F-18 DOPA (FDOPA) and Ga-68 DOTATATE (TATE) shows the most promising results to detect medullary thyroid cancer (MTC) recurrence. We performed this comparative study to detect the site of recurrent or metastatic disease in MTC patients with elevated serum calcitonin (Ctn) and/or carcinoembryonic antigen (CEA) levels. METHODS: We studied 46 MTC patients (25 women, 21 men) with elevated Ctn and/or CEA levels during follow-up who had both FDOPA and TATE PET/CT scans for re-staging purposes. RESULTS: FDOPA PET imaging yielded an overall sensitivity of 86.8%, specificity of 100%, PPV of 100%, NPV of 61.5%, and accuracy of 89.1%, while TATE PET scan had the same values as 84.2%, 87.5%, 96.9%, 53.8%, and 84.6%, respectively, and there was no statistically significant difference between the two modalities with the exception of the specificity value that was higher for FDOPA imaging. In a subgroup of patients with overt Ctn or CEA elevation, sensitivity of FDOPA increased significantly, whereas TATE sensitivity did not change. FDOPA PET imaging was significantly superior in detecting liver and regional lymph node (LN) metastases, while TATE PET scan was significantly better in the skeletal metastases. Early FDOPA demonstrated 11 invisible lesions on late FDOPA. CONCLUSION: Both FDOPA and TATE PET/CT imaging are useful to localize recurrences in MTC patients. While TATE imaging is superior to reveal skeletal disease, FDOPA seems better in liver and regional LN metastases; therefore, the two modalities appear complementary in monitoring MTC patients with elevated serum Ctn and/or CEA levels.

The Role of 68GA-PSMA PET/CT Scan In Patients with Prostate Adenocarcinoma who Underwent Radical Prostatectomy.

PURPOSE: To determine whether a 68Ga-PSMA PET/CT scan evaluation before radical prostatectomy (RP) is an effective imaging modality for clinical local and lymph node (LN) staging compared with the pathological results. MATERIALS AND METHODS: We performed a preoperative 68Ga-PSMA PET/CT scan in 51 patients with prostate cancer (PCa), who were scheduled for an RP operation between January 2014 and June 2016 in our clinic. The correlation between the RP pathology and the results of the 68Ga-PSMA PET/CT scan was investigated. RESULTS: When the 68Ga-PSMA PET/CT scan results were evaluated according to the risk groups, intraprostatic activity was found in 5 of 12 patients (41.7%) in the low-risk group, 15 of 19 patients in the intermediate risk group (78.9%), and 90% patients in the high-risk group. The 68Ga-PSMA PET/CT scan sensitivity, specificity, positive and negative predictive values and accuracy were calculated as 58.2%, 75.3%, 84.4%, 44%, and 63%, respectively for intraprostatic tumor localization; 68.4%, 75%, 61.9%, 80%, and %72.6%, respectively for extracapsular extension; 63.6%, 92.3%, 70%, 90%, and 86%, respectively for seminal vesicle involvement; 50%, 100%, 100%, 88%, and 89.3%, respectively for LN metastasis. CONCLUSION: The 68Ga-PSMA PET/CT scan accurately demonstrates intraprostatic tumor localization in high-risk group and presence of seminal vesicle involvement, which can help to accurately detect the target lesion before prostate biopsy. In addition, with its high sensitivity and specificity values, 68Ga-PSMA PET/CT is a valuable imaging method for the assessment of LN metastasis in intermediate- and high-risk groups and also provides accurate nodal staging before RP.

The role of 68Ga-DOTATATE PET/CT and 18F-FDG PET/CT in the follow-up of patients with medullary thyroid cancer.

OBJECTIVE: Medullary thyroid cancer (MTC) is an aggressive form of thyroid malignancy with local metastasis in 30%-50% of the cases and distant metastasis predominantly to lung, liver and skeleton in 13%-15% of patients. Identification of the lesion using imaging modalities is of crucial importance for disease management in the recurrent or metastatic MTC. In this study, we aimed to determine the efficacy of fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) and gallium-68 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid tyrosine-3-octreotate (68Ga-DOTATATE) PET/CT imaging in patients with MTC and to evaluate the relationship between imaging findings and serum tumor markers. MATERIALS AND METHODS: The records of MTC patients, who were treated and followed-up in our department between the years 2005 and 2018 were retrospectively analyzed. Seventy-three patients with MTC, who underwent either 68Ga-DOTATATE PET/CT (n=61) and/or 18F-FDG PET/CT (n=59) together with serum calcitonin (Ctn) and/or carcinoembryogenic antigen (CEA) measurement within 6 months period were included in the study. Gallium-68-DOTATATE PET/CT and 18F-FDG PET/CT scans performed within 6 months on the same patient (n=38) were analyzed separately for comparison of the efficacy of both modalities. RESULTS: The overall sensitivity of 18F-FDG PET/CT and 68Ga-DOTATATE PET/CT were 72.4% and 88.1%, respectively in detecting recurrent or metastatic disease. In the group of patients, who had both 18F-FDG PET/CT and 68Ga-DOTATATE PET/CT within 6 months interval (median: 1.14 months; range: 0.03 - 5.7 months), no significant difference was found in the overall sensitivity of both imaging modalities, however 68Ga-DOTATATE PET/CT was found to be more sensitive in detection of bone lesions compared to 18F-FDG PET/CT (P=0.005). CONCLUSION: Both 18F-FDG PET/CT and 68Ga-DOTATATE PET/CT are efficient imaging modalities in detection of recurrent or metastatic disease in MTC patients. Gallium-68-DOTATATE PET/CT could be more beneficial in detection of bone metastases with respect to 18F-FDG PET/CT.

Correlation of SUVmax and Apparent Diffusion Coefficient Values Detected by Ga-68 PSMA PET/MRI in Primary Prostate Lesions and Their Significance in Lymph Node Metastasis: Preliminary Results of an On-going Study

Objectives: Gallium-68 (Ga-68) prostate specific membrane antigen (PSMA) positron emission tomography (PET) has been shown to be more accurate than multiparametric prostate magnetic resonance imaging (MRI) in detection of primary prostate lesions. Using hybrid PET/MRI we aim to detect the correlation between SUVmax and apparent diffusion coefficient (ADC) in primary prostate lesions and to assess their prognostic value in detection of lymph node (LN) metastasis. Methods: Twenty-six patients, who were diagnosed as having prostate cancer with biopsy and underwent Ga-68 PSMA PET/MRI together with biparametric prostate MRI (bpMRI) were included. SUVmax, SUVmean and ADC were recorded for index lesions drawing a region of interest (ROI) of 1 cm2 around the pixel with the highest SUVmax (ROI-1) and another ROI following borders of prostate tumor detected by bpMRI (ROI-2). Presence of LN metastasis was recorded according to PSMA PET/MRI Results: SUVmax was inversely correlated with ADC (ROI-1: p=0.010; ROI-2: p=0.017 for b=800). SUVmax and SUVmeans were both higher in patients with LN metastasis and ADC was lower in patients with LN metastasis for ROI-1. SUVmax cut-off value of 19.8 for ROI-1 and 20.9 for ROI-2 had sensitivity and specificity of 77.8% and 76.5%, respectively for detection of LN metastasis, whereas ADC (b=800) cut-off value of 0.92x10-3 mm2/s had sensitivity and specificity of 87.5% and 76.5%, respectively. SUVmax/ADC (b=800) ratio increased the sensitivity and specificity to 100% and 82.4%, respectively. Conclusion: SUV and ADC values are inversely correlated in primary prostate lesions and the combined use of both values increases the diagnostic accuracy of hybrid PET/MRI in the detection of primary prostate lesions.

Comparison of Ga-68 PSMA positron emission tomography/computerized tomography with Tc-99m MDP bone scan in prostate cancer patients

Background/aim: The aim of our study was to compare Tc-99m MDP bone scan and Ga-68 PSMA PET/CT in terms of detection of bone metastasis in prostate cancer patients. Materials and methods: A total of 28 prostate cancer patients with bone scan and PSMA PET/CT performed within 90 days were retrospectively included in our analysis. All bone lesions were scored as negative (score-0), positive (score-1), or suspicious (score-2) for metastasis by two experienced nuclear medicine physicians. Both patient-based and region-based analyses were made for all osseous lesions. Results: On per-patient analysis; sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were 72.7%, 52.9%, 50%, 75%, and 60.7%, respectively, for bone scan and 90.9%, 100%, 100%, 94.4%, and 96.4%, respectively, for PSMA PET/CT. On per-region analysis; sensitivity, specificity, PPV, NPV, and accuracy were 76.2%, 80.9%, 57.1%, 91.1%, and 79.8%, respectively, for bone scan and 85.7%, 100%, 100%, 95.5%, and 95.4%, respectively, for PSMA PET/CT. Conclusion: Ga-68 PSMA PET/CT has higher sensitivity, specificity, and accuracy compared to bone scan in terms of bone metastasis detection in prostate cancer patients. Therefore, it might be the modality of choice for patients with suspicion for metastatic disease, despite negative bone scan and conventional imaging results

Clinical significance of standardized uptake values in thyroid incidentaloma discovered by F-18 fluorodeoxyglucose positron emission tomography/computed tomography.

AIM OF STUDY: While using F-18 fluorodeoxyglucose (FDG) positron emission tomography computed tomography (PET/CT) for other than thyroid disease, an increased frequency of incidentally discovered areas of focally or diffuse increased uptake within the thyroid gland can be seen. We aimed to find the focal thyroid FDG uptake and compare the maximum standardized uptake value (SUVmax) results with cytology and histology results. MATERIALS AND METHODS: We examined PET scan reports for all patients undergoing FDG PET/CT investigation over a 10-year period in a single center. Twelve thousand seven hundred and ninety-six patients underwent FDG PET/CT scanning in one PET/CT unit. Within this group, 526 patients had diffuse, focal, or multifocal FDG uptake. About 305 of 526 patients (57.9%) showed diffuse FDG uptake and 221 (42%) showed focal uptake on thyroid gland. RESULTS: The malignant group thyroid nodule sizes were between 8 and 39 mm (21.1 mm average, standard deviation [SD] ±7.3) on ultrasonography (USG) examination. These nodules have SUVmax values between 2.3 and 31.2 (average 8.8 SD ± 5.7). Benign group thyroid nodule sizes were between 5 and 46 mm (average 18.3 mm, SD ± 5.8) on USG examination. There were no significant correlations between SUVmax of the incidental focal thyroid lesions seen on FDG PET/CT and fine needle aspiration biopsy results. CONCLUSION: There is a relatively high possibility of a malignant lesion in thyroid incidentaloma. FDG uptake of these lesions is not a useful tool in absolute discrimination between malignancy and benign lesion. The presence of primary or secondary malign lesion is diagnosed in 34.1% of the patients who are found to have incidental focal FDG uptake within thyroid gland in PET/CT scans, but we suggest that the thyroid incidentalomas detected on FDG PET/CT should be further examined with USG and scintigraphy.

Normal distribution pattern and physiological variants of 68Ga-PSMA-11 PET/CT imaging.

PURPOSE: Ga-PSMA-11 is a novel PET tracer suggested to be used for imaging of advanced prostate cancer. In this study, we aimed to present a detailed biodistribution of Ga-PSMA-11, including physiological and benign variants of prostate-specific membrane antigen (PSMA) imaging. MATERIALS AND METHODS: We carried out a retrospective analysis of 40 patients who underwent PSMA PET/computed tomography (CT) imaging and who had no evidence of residual or metastatic disease on the scans. In addition, 16 patients who underwent PSMA PET/CT imaging with any indication other than prostate cancer were included in the study to evaluate physiological uptake in the normal prostate gland. The median, minimum-maximum, and mean standardized uptake value (SUV) values were calculated for visceral organs, bone marrow and lymph nodes, and mucosal areas. Any physiological variants or benign lesions with Ga-PSMA-11 were also noted. RESULTS: Ga-PSMA-11 uptake was noted in the kidneys, parotid and submandibular glands, duodenum, small intestines, spleen, liver, and lacrimal glands, and mucosal uptake in the nasopharynx, vocal cords, pancreas, stomach, mediastinal blood pool, thyroid gland, adrenal gland, rectum, vertebral bone marrow, and testes. Celiac ganglia showed slight Ga-PSMA-11 uptake in 24 of 40 patients without the presence of any other pathologic lymph nodes in abdominal and pelvic areas. Variable uptake of Ga-PSMA-11 was observed in calcified choroid plexus, a thyroid nodule, an adrenal nodule, axillary lymph nodes and celiac ganglia, occasional osteophytes, and gallbladder. The patient group with PSMA PET/CT for indications other than prostate cancer (n=16) showed a slight radiotracer uptake in normal prostate gland (SUVmax: 5.5±1.6, range: 3.5-8.3). CONCLUSION: This study shows normal distribution pattern, range of SUVs, and physiological variants of Ga-PSMA-11. In addition, several potential pitfalls were documented to prevent misinterpretations of the scan.