US-guided percutaneous ablation of thyroid nodules with 177LU-MAA (LUTMA) - Feasibility study.

PURPOSE: The main purpose is to evaluate the safety, and efficacy of 177Lutetium labeled macroaggregated albumin (LUTMA) ablation of thyroid nodules. MATERIALS AND METHODS: Patients with confirmed benign nodules who were not candidate or did not accept surgery were enrolled. Under ultrasonography (USG) guidance, LUTMA which was produced in our department, was administered into the nodules. Nodule volumes were assessed via USG before the injection and at 1-week, 1-month, and 3-months post-treatment. We calculated the volume reduction rates (VRRs) for these intervals. To detect extranodular activity leakage, patients underwent SPECT/CT imaging at one hour, 24 h, and one week post-injection. RESULTS: Fifteen patients (male: 12, female: 3) with benign thyroid nodules were eligible to join this study. These nodules were categorized as cystic (n = 9), solid (n = 3), or mixed (n = 3). Median nodules volume was 6.59 ml (range: 0.56-55 ml). Predicted absorbed dosee to the nodules varied between 10-1036 Gy. The VRRs at 3 months was 85% for all nodule types with gradual increases over time: 0%-92%, 20%-97%, and 28%-98% at 1 week, 1 month, and 3-months, respectively. The median VRR of cystic nodules was 89% (range: 81%-98%) at 3-months. It is significantly higher than solid ones (P = .009). None of the patients experienced adverse reactions or discomfort during the injection or follow-up. CONCLUSION: LUTMA treatment significantly reduces the volume of benign thyroid nodules, offering relief from disease-associated symptoms and cosmetic concerns. It emerges as a promising alternative to surgical and other local treatments for benign thyroid nodule ablation. CLINICAL SIGNIFICATION: LUTMA is a novel theranostic radiopharmaceutical which is promising in local ablative treatment of benign thyroid nodules.

Synchronous occurrence of medullary and papillary thyroid cancer and survival rates.

PURPOSE: Concurrence of medullary and papillary thyroid carcinoma (MTC and PTC) represents less than 1% of all thyroid malignancies. We aimed to reveal the demographic and clinical characteristics of this rare pathology and to evaluate the effect of the same or contralateral lobular localization of these two malignancies in clinical and laboratory features. Evaluation of progression-free survival (PFS) in current pathology is one of the important features of our study. METHODS: All patients diagnosed with simultaneous MTC and PTC after thyroidectomy were evaluated retrospectively. Data on the following variables were recorded: age, gender, tumor localization (ipsilateral lobe located MTC and PTC-Group I, contralateral lobe located MTC and PTC-Group II), tumor size, cervical lymph node metastasis, distant metastasis, tumor stage, postoperative basal calcitonin, carcinoembryonic antigen, thyroglobulin (Tg), and anti-Tg values. In all our cases, since MTC progressed before PTC, progression was accepted as serum calcitonin values exceeded 150 pg/mL. RESULTS: Groups were formed as follows: Group I, four cases where MTC and PTC were localized in different foci in the same lobe; Group II, nine cases where they were localized in different lobes. There was only one case in which two tumors were located in the same focus. The case with dual differentiation was included in Group I (35. 7%). When the PFS of the two groups were compared, no statistically significant difference was found ( P = 0.87). CONCLUSIONS: As a result of this analysis, the location of the simultaneously detected PTC in the same or different lobes with the MTC does not make a significant difference in clinical and laboratory features.

Investigation of Clinical Histopathologic Features and Metabolic Parameters of 18F-FDG PET/CT in Invasive Breast Carcinoma with a Micropapillary Component.

Objectives: The aim of this study was to evaluate the correlation between clinical histopathologic features and micropapillary (MP) ratio with the maximum standardized uptake value (SUVmax) derived from 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) in treatment naïve breast cancer. Methods: Twenty-nine patients diagnosed with breast cancer with a MP component who underwent PET/CT imaging before any local and/or systemic treatment were included in this retrospective study. All clinical histopathological features were recorded. SUVmax values were measured from 18F-FDG PET images for primary tumors and metastatic axillary lymph nodes. Results: MP component percentage did not correlate with any clinical histopathological features except age. At early ages, the MP component ratio was significantly higher. Our results showed that there is no significant correlation between the SUVmax value and MP component percentage. Conclusion: A high SUVmax value is generally expected in aggressive malignancies. However, this assumption may not be valid for the MP subgroup, which has an aggressive course compared to other subgroups in breast cancer.

The role of endobronchial ultrasonography elastography in the diagnosis of hilar and mediastinal lymph nodes.

BACKGROUND: Endobronchial ultrasonography (EBUS) is a minimally invasive diagnostic tool in the diagnosis of mediastinal lymph nodes (LNs) and has sonographic features. We aimed to investigate the diagnostic accuracy of EBUS elastography, which evaluates tissue compressibility integrated into EBUS, on malignant vs. benign mediastinal-hilar LNs. METHODS: A single-center, prospective study was conducted at the University of Health Sciences Yedikule Chest Diseases and Thoracic Surgery Training and Research Hospital between 01/10/2019 and 15/11/2019. The features of 219 LNs evaluated by thoracic computed tomography (CT), positron emission tomography (PET)/CT, EBUS sonography and EBUS elastography were recorded. The LNs sampled by EBUS-guided fine needle aspiration were classified according to EBUS elastography color distribution findings as follows: type 1, predominantly nonblue (green, yellow, and red); type 2, part blue, part nonblue; type 3, predominantly blue. The strain ratio (SR) was calculated based on normal tissue with the relevant region. RESULTS: The average age of 131 patients included in the study was 55.86 ± 13 years, 76 (58%) were male. Two hundred and nineteen lymph nodes were sampled from different stations. Pathological diagnosis of 75 (34.2%) LNs was malignant, the rest was benign. When EBUS B-mode findings and pathological results were compared, sensitivity was 65.33%, specificity 63.19%, positive predictive value (PPV) 48%, negative predictive value (NPV) 77.8%, and diagnostic yield (DY) 64%. When the pathological diagnoses and EBUS elastography findings were compared, while type 1 LNs were considered to be benign and type 3 LNs malignant, sensitivity 94.12%, specificity 86.54%, PPV 82.1%, NPV 95.7%, and DY 89.5%. SR of malignant LNs was significantly higher than benign LNs (p < 0.001). When the classification according to color scale and SR were compared, no difference was found in DY (p = 0.155). DISCUSSION: The diagnostic accuracy of EBUS elastography is high enough to distinguish malignant LN from benign ones with the SR option. When compared with EBUS-B mode sonographic findings, it was found to have a higher diagnostic yield.

Neuroendocrine Tumor of Tailgut Cyst with Unexpected Metastases.

Neuroendocrine tumors (NETs) originate from the neuroendocrine cells, which are found in various organs. NETs occur frequently in the gastrointestinal tract. NETs arising from tailgut cysts are uncommon. We herein report an interesting case of metastatic tailgut cyst NET, which was firstly diagnosed as plasmacytoma.

The effectiveness of bone scintigraphy in the management of low back pain.

BACKGROUND: Back and low back pain have been reported as one of the leading causes of activity restriction. While degenerative changes in the spine are among the common causes of low back pain, zygapophyseal (facet) joint pain is seen as the most widely accepted cause of back pain. Standard imaging modalities may have low predictive value in detecting the source of back pain. Thanks to radionuclide bone scintigraphy, painful lesions can be distinguished from age-related changes, especially in patients with chronic low back pain. In this study, we aimed to retrospectively evaluate the clinical results of facet-induced low back pain, which was confirmed by bone scintigraphy, after facet injection treatment. METHODS: We completed a retrospective review of patients who underwent diagnostic radionuclide bone scintigraphy imaging for low back pain at our institution from 2019 to 2021. Scintigraphy imaging was often performed in conjunction with traditional diagnostic imaging. The patients underwent injection at the levels that were decided by the referring physician on the basis of the clinical symptoms, the physical examination findings, and findings on existing radiologic images, with performance of bone scanning. RESULTS: The patients consisted of 24 (47.1 %) males and 27 (52.9 %) females with a mean age of 44.03 ± 9.26 years (range 34-67 years) at initial symptom onset. In the bone scintigraphy, increased radioactive uptake was detected in the facet joints of the lumbar region in 33 of 51 (64.7 %) patients. Statistically significant improvement was found in VAS-ODI and SF-36 scorings in 30 patients (90.1 %) after injection in patients with increased radioactive uptake. Statistically significant improvement was found in VAS-ODI and SF-36 scorings in 12 (66.6 %) patients who had no pathological findings with imaging modalities and were injected according to physical examination. When the two groups were compared with each other, the success rate in the group with increased radioactive uptake was found to be statistically significantly higher (p < 0.01) CONCLUSIONS: Application of this technology may lead to more reliable diagnosis and treatment of painful facet arthropathy. Appropriate diagnostic tests and determination of spinal level localization will provide satisfactory results with correct patient selection.

Is there any additional benefit of 68Ga-PSMA PET on radiotherapy target volume definition in patients with glioblastoma?

OBJECTIVE: To investigate the contribution of 68Gallium (68Ga)-PSMA (prostate-specific membrane antigen) positron emission tomography (PET) in defining radiotherapy (RT) target volume for glioblastoma and to compare the target volumes defined by Magnetic Resonance Imaging (MRI). METHODS: RT planning Computed Tomography (CT) images were fused separately with pre-operative MRI and PET/MRI images of 10 glioblastoma patients, retrospectively. The contrast-enhanced area in T1 weighted MRI was contoured as gross tumor volume (GTV) and clinical target volume (CTV1) was obtained by including the cavity and T2/FLAIR hyperintense areas after giving a margin of 2 cm to the GTV. 68Ga-PSMA uptake area was contoured as biological tumor volume (BTV) and CTV2 was obtained with a margin of 2 cm to BTV. Planning target volumes (PTVs) were created with the 3 mm added to the CTVs. Conformity index (CI), dice similarity coefficient (DSC) and overlap volume (OV) were calculated by obtaining the intersection and union volumes. Volumetric comparison, similarity and overlap analyzes were performed statistically by Wilcoxon signed rank and One sample t-test. RESULTS: The median GTV was 21,96 cc (1,04 - 82,04) and BTV was 25,58 cc (2,43 - 99,47). BTV was on average 47% larger than GTV which was statistically significant (p = 0.03). For GTV-BTV, CTV1-CTV2 and PTV1-PTV2; mean values of CI were 0,56, 0,76 and 0,76; DSC were 0,70, 0,86 and 0,86; OV were 0,88, 0,94 and 0,94, respectively. There was no significant difference on size and spatial similarity between CTV1 and CTV2, PTV1 and PTV2. CONCLUSION: Altough BTV was larger than GTV, this significance was lost while we gave the same CTV margin including the peripheral edema. It seems that it may help to improve defining non-enhancing tumor part and also recurrent tumor volume. ADVANCES IN KNOWLEDGE: Recent studies have focused on the role of 68Ga-PSMA PET in imaging of glial tumors. It has been observed that 68Ga-PSMA PET can clearly define the tumor borders and it can be beneficial in target volume delineation, especially in reirradiation of recurrent tumors.

Comparison of brain F-18 FDG PET/MRI with PET/CT imaging in pediatric patients.

BACKGROUND: Standardized uptake values (SUVs) are important indexes for evaluating the accuracy of disease diagnoses achieved via fluoro-18 deoxyglucose (F-18 FDG) positron emission tomography/computed tomography (PET/CT) and positron emission tomography/magnetic resonance imaging (PET/MRI). The purpose of this study is to describe normal cerebral FDG uptake in the pediatric population and compare SUVmax/mean results for brain images obtained from PET/CT and PET/MRI in neurologically healthy pediatric examinees. METHODS: This study included 20 patients who were < 18 years of age and were without intracranial malignancy and/or brain disorders. Patients underwent either PET/CT imaging (n = 10) or PET/MRI imaging (n = 10) after 70-80 min of F-18 FDG injection. The SUVmax and SUVmean for various brain regions were calculated and compared between sides and imaging modalities using with appropriate statistical tests. RESULTS: The median SUVmax/SUVmean values of the right-sided frontal, parietal, temporal, and occipital lobes were 8.63/ 6.18, 8.85 / 6.97, 6.88 / 4.99, and 11.06 / 7.02 in PET/CT, respectively, and 11.45 / 8.59, 10.16 / 8.47, 8.82 / 6.6, and 11.71 / 8.25 in PET/MRI, respectively. The median SUVmax/SUVmean values of the left-sided frontal, parietal, temporal, and occipital lobes were 9.05 / 6.86, 8.03 / 6.62, 6.49 / 4.77, and 10.6 / 7.73 in PET/CT, respectively, and 10.7 / 8.16, 11.06 / 7.88, 8.13 / 6.09, and 10.96 / 9.22 in PET/MRI, respectively. CONCLUSIONS: These results showed that there was no statistically significant difference in SUVs values between the two brain imaging modalities except from SUVmax value of left-sided parietal lobe and no asymmetric radiopharmaceutical uptake between the left and right brain regions or cerebellums in each modality, suggested that in brain imaging, PET/MRI can be used reliably instead of PET/CT.

68Ga PSMA PET/MR in the differentiation of low and high grade gliomas: Is 68Ga PSMA PET/MRI useful to detect brain gliomas?

BACKGROUND: Magnetic resonance imaging (MRI) is the most important imaging modality in the diagnosis and follow-up of glial brain tumors. OBJECTIVE: The aim of our study is to determine the correlation between tumor grade, determined with postoperative pathological examination, and standard uptake value (SUV), a semi-quantitative parameter, in patients who underwent imaging 68Ga-PSMA with using PET/MR. MATERIAL-METHOD: Thirty-five out of 38 patients' images whose pathology was consistent with glial tumor, 42 lesions from separate anatomic localizations or with higher activity uptake than the rest of the tumor were evaluated. SUV values measured on PET images and grade relationship were evaluated based on each lesion while mitosis, Ki-67 were evaluated for each patient. RESULTS: Grade, Ki-67, mitosis, necrosis and SUVmax/mean/peak were found statistically significant with moderate/high correlation. The parameter with the highest correlation coefficient was mitosis. (For SUVmax r = 0.64, p = 0). When Grade II and III were considered as the first group and IV as the second group, the cutoff values were found to be 2.3 for SUVmax, 0.21 for SUVmean and 0.63 for SUVpeak. In the diagnosis of HGG, PET's sensitivity is higher than MRI but no statistically difference was found between specificities. CONCLUSION: 68Ga PSMA PET imaging is found to be particularly useful in differentiating Grade IV glial tumors from other grades. This finding is thought to be important in the differentiation the relapse with postoperative tissue changes, which is an important problem in the follow-up.

The contribution of SPECT/CT in patients with radionuclide shuntography through shunt dysfunction.

OBJECTIVE: Radionuclide CSF study is a simple, effective, and low-radiation-dose procedure for the assessment of shunt patency. With the help of CT image of single-photon emission computed tomography/computed tomography (SPECT/CT), the interpretation becomes more accurate and easier.The aim of this study was to compare the classical methods and 2D planar scintigraphic images with radionuclide shuntography fused SPECT/CT. METHODS: Between 2015-2019 all hydrocephalic patients who underwent radionuclide shuntography and classical methods (cranial CT, USG and/or direct X-rays), for suspected VP shunt malfunction at our hospital were retrospectively enrolled in the study. Fusion with SPECT/CT is provided in all radionuclide shuntographies. Approximately 0.5-1 mCi diethylene-triaminepentaaceticacid (DTPA) was intrathecally injected. Images were collected as 5-second frames for the first minute, and 1-min frames for the second to the 30th min. Static whole body images were obtained as early (30 min) and delayed (120 min) images. SPECT/CT was performed in 120 min. RESULTS: When the classical methods were evaluated in the operated patients, according to the direct radiographic findings, in only 17 patients had shunt dysfunction due to disconnection-kinking or laceration, was obtained.On the other hand,while67 shuntography were evaluated,65 of these patients (97%) whose intraoperative and shuntography findings were found to be compatible with each other. CONCLUSION: The 3D SPECT images combined with the two-dimensional planar images added to the CT provide more accurate information and also provide detailed anatomical information. The patient's operation was performed successfully in one session in cooperation with the other surgical branches when needed.

Performance of F-18 Fluorocholine PET/CT for Detection of Hyperfunctioning Parathyroid Tissue in Patients with Elevated Parathyroid Hormone Levels and Negative or Discrepant Results in conventional Imaging.

OBJECTIVE: Our aim was to assess the diagnostic performance of F-18 fluorocholine (FCH) positron emission tomography/computed tomography (PET/CT) in detecting hyperfunctioning parathyroid tissue (HPT) in patients with elevated parathyroid hormone levels with negative or inconclusive conventional imaging results and to compare the findings with those obtained using technetium-99m sestamibi (MIBI) scintigraphy and neck ultrasonography (US). MATERIALS AND METHODS: Images of 105 patients with hyperparathyroidism who underwent FCH PET/CT, dual-phase MIBI parathyroid scintigraphy (median interval: 42 days), and neck US were retrospectively analyzed. The gold standard was histopathological findings for 81 patients who underwent parathyroidectomy and clinical follow-up findings in the remaining 24 patients. Sensitivities, positive predictive values (PPVs), and accuracies were calculated for all imaging modalities. RESULTS: Among the 81 patients who underwent parathyroidectomy, either parathyroid adenoma (n = 64), hyperplasia (n = 9), neoplasia (n = 4), or both parathyroid adenoma and hyperplasia (n = 1) were detected, except 3 patients who did not show HPT. Of the 24 (23%) patients who were followed-up without operation, 22 (92%) showed persistent hyperparathyroidism. FCH PET/CT showed significantly higher sensitivity than MIBI scintigraphy and US in detection of HPT (p < 0.01). Sensitivity, PPV, and accuracy of FCH PET/CT were 94.1% (95/101), 97.9% (95/97), and 92.4% (97/105), respectively. The corresponding values for MIBI scintigraphy and US were 45.1% (46/102), 97.9% (46/47), and 45.7% (48/105) and 44.1% (45/102), 93.8% (45/48), and 42.9% (45/105), respectively. Among the 35 patients showing negative MIBI scintigraphy and neck US findings, 30 (86%) showed positive results on FCH PET/CT. FCH PET/CT could demonstrate ectopic locations of HPT in 11 patients whereas MIBI and US showed positive findings in only 6 and 3 patients, respectively. CONCLUSION: FCH PET/CT is an effective imaging modality for detection of HPT with the highest sensitivity among the available imaging techniques. Therefore, FCH PET/CT can be recommended especially for patients who show negative or inconclusive results on conventional imaging.

Comparison of PERCIST and RECIST criteria for evaluation of therapy response after yttrium-90 microsphere therapy in patients with hepatocellular carcinoma and those with metastatic colorectal carcinoma.

OBJECTIVE: Yttrium-90 (Y) microsphere therapy has been increasingly used to treat hepatocellular carcinoma (HCC) and liver metastasis of colorectal cancer (mCRC). This study aims to compare two different criterias used for therapy response evaluation following Y therapy within the same group of patients. PATIENTS AND METHODS: A total of 21 patients with HCC and 19 patients with mCRC were included in this study, with 36 and 42 liver lesions, respectively. The lesions were evaluated before and after therapy by CT or MRI and fluorine-18 fluorodeoxyglucose (F-FDG) PET/CT. Several metabolic parameters were analyzed including maximum and mean standardized uptake values, peak standardized uptake value, metabolic tumor volume (MTV), and total lesion glycolysis. Tumor volume was determined using CT or MRI images for all lesions, and the applied activity was estimated to deliver 120±20 Gy for the treated lobe. Six weeks after Y microsphere therapy, F-FDG PET/CT scan was performed to evaluate tumor response using PERCIST and RECIST criteria. Overall survival was calculated using Kaplan-Meier method. RESULTS: A total of 78 liver lesions were treated without any major complication. The mean tumor volumes of HCC lesions calculated by CT or MRI before and after therapy were 84.38 and 86.62 cm, respectively. The average MTV of these lesions on PET images was calculated as 68.142 mm before therapy and 56.945 mm after treatment. In patients with mCRC, the mean tumor volume was 52.32 cm before therapy and 54.52 cm after therapy. The average MTV was calculated as 41.720 mm before and 44.967 mm after therapy for the same patient group. Response Evaluation Criteria In Solid Tumors (RECIST) and PET Response Criteria In Solid Tumors incompatibility was seen in seven of 36 lesions in HCC-diagnosed patients and seven of 42 lesions in patients with mCRC. The mean overall survival was calculated as 13.09 months in patients with HCC and 10.6 months in patients with mCRC. CONCLUSION: Y therapy response can be evaluated by both RECIST and European Organization for Research and Treatment of Cancer criteria. However, RECIST and European Organization for Research and Treatment of Cancer incompatibility can be seen. The anatomic methods for evaluating HCC response is relatively more accurate, whereas the metabolic parameters guided by PET/CT scan showed greater importance in response to evaluation of liver mCRC.

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

What happens to temporal hypometabolism contralateral to side of surgery in patients with bilateral temporal hypometabolism?

OBJECTIVE: To see what happens on PET hypometabolism on the temporal lobe contralateral to the side of surgery in patients with bitemporal hypometabolism (BTH). PATIENTS AND METHODS: This retrospective study with prospectively defined data evaluated the pre- and post-surgical PET hypometabolism on the contralateral temporal lobe after resection of ipsilateral temporal lobe in 10 patients with BTH operated between January, 2010 and May, 2018. On PET we compared standard uptake values (SUV) and relative metabolic activities as compared to normal subjects by means of Z-scores of hypometabolism of unresected temporal lobes before and after surgery. RESULTS: Surgery did not lead to satisfactory seizure outcome and only 3 patients were seizure free. All but one were still using anti-epileptic drug. No significant change was noted on PET hypometabolism related to the contralateral temporal lobe at the last follow-up. Regarding the mean SUV, comparisons showed that the difference with respect to the mesial structures was significant (p = 0.04). But lateral cortex showed insignificant difference (p = 0.21) before and after surgery. Regarding the mean Z-score, no significant differences were found between both the mesial temporal structures (p = 0.23) and lateral temporal cortex (p = 0.18). CONCLUSION: Surgery does not lead to improvements on PET hypometabolism of the temporal lobe contralateral to the side of surgery and hypometabolism on the contralateral side may be due to structural damage rather than functional deficits secondary to propagation of repetitive seizures. Seizure outcome is not satisfactory and before surgery patients or their next of kin should be informed in detail.

Can SUVmax values of Ga-68-PSMA PET/CT scan predict the clinically significant prostate cancer?

PURPOSE: The intensity of prostate-specific membrane antigen (PSMA) expression increases as the tumor grade increases and the uptake of Ga-68-PSMA is higher in high-grade tumors. The aim of the present study was to evaluate the correlation of preoperative tracer uptake of primary tumor to Gleason Score in patients who underwent prostatectomy. PATIENTS AND METHODS: We retrospectively evaluated 141 patients who had Ga-68-PSMA positron emission tomography/computed tomography (PET/CT) imaging and who underwent prostatectomy. All patients had a diagnosis of prostate cancer on the basis of 10-24 cores transrectal ultrasound-guided biopsy (TRUS-Bx). Histological assessment was performed according to the New Contemporary Prostate Cancer Grading System. All patients had a prostate-specific antigen (PSA) level measurement within maximum of 28 days before Ga-68-PSMA PET/CT. Region of interests were drawn manually around the prostate gland, avoiding the bladder activity, to calculate the maximum standardized uptake values (SUVmax) values. RESULTS: The median PSA values for all patients were 10.0 ng/ml. PSA values for low-risk patients were significantly lower than those of high-risk patients (P<0.001). There were 41.1% upgrades and 7.8% downgrades following prostatectomy in terms of Grade Groups. According to the final pathology reports, 21% (n=16) of patients moved from a low-risk level (grade groups 1+2) to a high-risk level (grade groups 3+4+5). The median SUVmax value was 8.8, ranging from 2.1 to 62.4. There was a strong correlation between SUVmax values and grade groups (Pearson ρ=0.66) (P<0.001). The mean SUVmax values of high-risk patients were significantly higher than those of low-risk patients (18.9±12.1 vs. 7.16±6.2, respectively) (P<0.001). Receiver operation characteristic curve analysis of SUVmax at the cut-off value of 9.1 showed a high sensitivity (78%) and specificity (81%) for detection of high risk disease. CONCLUSION: SUVmax values correlate significantly with the grade groups of the primary tumor. The intraprostatic accumulation sites may predict clinically significant cancer and potentially serve as a target for biopsy sampling in conjunction with mpMRI in selected patients.