Prognostic significance of 68 Ga-FAPI PET/CT in patients with bone metastases in various cancers.

OBJECTIVE: This study aimed to compare 18FDGPET/CT in patients who develop bone metastases due to various cancers and to investigate the prognostic significance of the 68FAPI-PET/CT SUVmax value for survival. METHODS: Patients with bone metastases who underwent both 68 Ga-FAPI PET/CT and 18FDGPET/CT within a 1 week period were included in this retrospective study. The effect of the SUVmax value of bone lesions on overall survival was analyzed. RESULTS: A total of 75 eligible patients with 139 bone lesions were included in this study. The median age of the patients was 55 (30-83) and 48(64%) patients were newly diagnosed. The primary lesion median 68 Ga-FAPI PET/CT SUVmax value was higher than the median 18FDGPET/CT SUVmax (10.75 versus 6.7). Bone lesions 68 Ga-FAPI PET/CT SUVmax median (IQR) were 7.8 (4.6-13.2), and 18FDGPET/CT SUVmax of bone lesions were 5.9 (3.8-8.2). More bone lesions were detected on 68 Ga-FAPI PET/CT than on 18FDGPET/CT(median IQR 4 [1-9] versus 2 [1-6] (p = 0.014). The extra lesions observed on 68 Ga-FAPI PET/CT were mostly sclerotic bone lesions (p = 0.001).68 Ga-FAPI PET/CT SUVmax was significantly higher in vertebra and thorax lesions (p = 0.011 and p = 0.018, respectively). While the bone lesion 68 Ga-FAPI PET/CT SUVmax affected the OS, the 18FDGPET/CT SUVmax value did not affect the OS (p < 0.001 and p = 0.079, respectively). In ROC analysis, a cut-off-off value of 68 Ga-FAPI PET/CT SUVmax > 7.7 was found for OS (AUC: 0.619). The median OS in the group above the cut-off value was worse than that in the group below the cut-off value (32 versus 45) months (p = 0.002). In the multivariate analysis for OS, the 68 Ga-FAPI PET/CT SUVmax of bone lesions was an important parameter, as well as cancer subtype, ALP level, and disease occurrence. CONCLUSIONS: 68 Ga-FAPI PET/CT detected more bone lesions and higher SUVmax values than 18FDGPET/CT in various cancers. The prognostic value of the SUVmax value of 68 Ga-FAPI PET/CT bone lesions was observed regardless of disease subtype.

177Lu-PSMA-617 Radioligand Treatment in Elderly Patients with Metastatic Castration-resistant Prostate Cancer: Therapeutic Efficacy and Safety Assessment.

OBJECTIVE: This study aimed to evaluate the therapeutic efficacy and safety of 177Lutetium-Prostate Specific Membrane Antigen (177Lu-PSMA-617) radioligand treatment (RLT) in metastatic castration-resistant prostate cancer (mCRPC) patients with aged older than 75 years. METHODS: A total of 37 patients with mCRPC aged older than 75 years treated with 177Lu- PSMA-617 were included in this study. Pre-therapy and post-therapy biochemical, metabolic, and clinical response results and Hb, TLC, platelet, serum creatinine and bilirubin levels were checked to evaluate the therapeutic efficacy and toxicity profile. The Common Terminology Criteria for Adverse Events was used for grading adverse events caused by 177Lu-PSMA-617 treatment. RESULTS: The mean age of the patients included in the study was 79.8±2.9 (76-92). The number of 177Lu-PSMA-617 treatment cycles ranged from two to four, and the mean administered radioactivity dose was 5.6±0.8 GBq per cycle. Partial biochemical response (PR) and partial metabolic response (PMR) were observed in 11 (29.7%) and 15 (40.6%) patients after treatment, respectively. Although improvement in ECOG scores was observed in 5 (13.5%) patients after treatment, it was not statistically significant. Grade 2 and 3 Hb toxicity was observed in 10 (27%) and 2 (5.4%) patients, respectively. Grade 2 leukocytopenia in six patients, Grade 1 thrombocytopenia in six patients, and Grade 2 serum creatinine toxicity in five patients were seen after the treatment. On the other hand, no patients developed liver toxicity and grade 3 or 4 leukocytopenia, thrombocytopenia or creatinine toxicity. CONCLUSION: 177Lu-PSMA-617 treatment was a safe and effective treatment option for properly selected elderly mCRPC patients.

Evaluation of the relationship between FDG-PET hypometabolism and retinal layer thickness in patients with Alzheimer's disease.

We aimed to investigate the diagnostic value of Optical coherence tomography (OCT) in Alzheimer's disease (AD) and to assess the correlation between OCT and fluorodeoxyglucose (FDG)-positron emission tomography (PET) which shows high diagnostic agreement with findings from postmortem histopathology-the gold standard method. Patients who were diagnosed with AD-related dementia were selected for the study. Patients with a mini mental test (MMT) score between 18 and 23 were included in the study (n = 31). Volunteers with MMT ≥ 28 and no cognitive impairment were included in the study as the control group (n = 31). OCT imaging was performed in the patient and control groups after detailed ophthalmological examinations including visual acuity and intraocular pressure measurements. Brain glucose metabolism measurement was performed using 18 F-FDG PET/computed tomography. When adjusted for age and sex, mean retinal nerve fiber layer thickness (RNFL) thickness showed a significant difference between groups and the RNFL thickness in the superior temporal and superior nasal quadrants in AD-related mild dementia group showed a significant difference (p < 0.05). Furthermore, only the RNFL thickness in the inferior nasal quadrant of the right eye showed a significant difference between the groups (p = 0.016). It is thought that OCT is a promising imaging method in the elderly population due to its low-cost, non-invasive and easily applicability, and therefore, it may contribute in the future as a tool in the periodic follow-up of patients diagnosed with AD.

68Ga-FAPI PET/CT as an Alternative to 18F-FDG PET/CT in the Imaging of Invasive Lobular Breast Carcinoma.

Accurate staging of invasive lobular carcinoma (ILC), a subtype of breast cancer, is vital for effective clinical management. Although 18F-FDG PET/CT is a commonly used tool, its efficacy varies across different histologic subtypes. To mitigate this challenge, our investigation delves into the potential utility of 68Ga-fibroblast activation protein inhibitor (FAPI) PET/CT as an alternative for staging ILC, aiming to address a significant research gap using a more expansive patient cohort than the smaller samples commonly found in the existing literature. Methods: In this retrospective analysis, women diagnosed with primary ILC of the breast underwent both 18F-FDG PET/CT and 68Ga-FAPI PET/CT. Both modalities were compared across all lesion locations with the used reference standard. The interval between scans was 1 wk, without any intervening treatments. Lesions were categorized visually, and tracer activity was analyzed using SUVmax, tumor-to-background uptake ratio, and uptake ratios. Both modalities were compared across various parameters, and statistical analysis was performed using SPSS 22.0. A P value of less than 0.05 was chosen to determine statistical significance. Results: The study included 23 female ILC patients (mean age, 51 y) with hormone-positive, human epidermal growth factor receptor type 2-negative tumors. Most (65%) had the luminal A subtype. 68Ga-FAPI PET/CT outperformed 18F-FDG PET/CT, with higher tumoral activity and tumor-to-background uptake ratios (P < 0.001). Primary tumors showed significantly increased uptake with 68Ga-FAPI PET/CT (P < 0.001), detecting additional foci, including multicentric cancer. Axillary lymph node metastases were more frequent and had higher uptake values with 68Ga-FAPI PET/CT (P = 0.012). Moreover, 68Ga-FAPI PET/CT identified more lesions, including bone and liver metastases. Pathologic features did not significantly correlate with imaging modalities, but a positive correlation was observed between peritumoral lymphocyte ratio and 68Ga-FAPI PET/CT-to-18F-FDG PET/CT uptake ratios (P = 0.026). Conclusion: This study underscores 68Ga-FAPI PET/CT's superiority over 18F-FDG PET/CT for ILC. 68Ga-FAPI PET/CT excels in detecting primary breast masses, axillary lymph nodes, and distant metastases; can complement 18F-FDG PET/CT in ILC; and holds potential as an alternative imaging method in future studies.

Lutetium-177-PSMA-617 radioligand therapy in patients with high volume metastatic prostate cancer prior to chemotherapy and new generation androgen deprivation therapy: Clinical Experience.

OBJECTIVE: We aimed to evaluate the efficacy oflutetium-177-prostate-specific membrane antigen-617 (177Lu-PSMA-617) with the luteinizing hormone releasing hormone (LHRH) analogues in the first or in the second-line setting formetastatic castration sensitive patients and metastatic castration resistance after progression with LHRH analogues. SUBJECTS AND METHODS: Sixteen consecutive patients with high volume metastatic prostate cancer undergone 177Lu-PSMA-617 therapy who were refused chemotherapy and were unable to use new generation anti-androgen drugs because of unavailibility of reimbursement, were included in this retrospective study. Prostate specific antigen (PSA) response (>50% decrease), disease control rate (DCR: complete or partial response), progression-free survival (PFS) and overall survival (OS) were calculated to evaluate according to the clinicopathological features of the patients. Treatment response evaluated by 68Ga-PSMA-11 positron emission tomography/computed tomography (PET/CT). RESULTS: Mean age was 74,6 (SD±8,36). Among them, 7 (43,8%) patients has castration resistant disease, while the remaining has castration sensitive disease. Lutetium-177-PSMA-617 was administered to 10 (62,5%) patients as one of the first-line treatment and 6 patients received the treatment after progression on LHRH as a second-line treatment. Considering all patients, PSA response rate and DCR were 50% and 62% respectively. The median PFS and OS (with 95% CI) were 11,2 months (11-15) and 29 months (25,6-32,4), respectively in patients treated with 177Lu-PSMA-617 and LHRH analogues. Clinicopathological features and basal PSA level did not have effect on PSA response rates, DCR, OS and PFS. On the other hand, increment in PFS and OS (with 95% CI) was observed in castration resistant disease and in the second-line therapy; for castration resistant disease 16,5 months (12.3-19.7); 30 months (25.3-32.7), for the second-line therapy 14.5 months (12-20.5); 29 months (NR), respectively but statistically not significant. Serious toxicity was observed in a limited number of patients (18,7%), treatment-related death was not observed. CONCLUSION: Favorable results can be achived with second-line 177Lu-PSMA-617 treatment in terms of OS and PFS, especially in castration-resistant disease, when chemotherapy and new generation ADT's cannot be used.

Comparison of 68Ga-FAPI-04 and 18F-FDG PET/CT for diagnosis of metastatic lesions in patients with recurrent papillary thyroid carcinoma.

OBJECTIVE: We aimed to evaluate the gallium-68-labeled fibroblast-activation protein inhibitor (68Ga-FAPI) positron emission tomography/computed tomography (PET/CT) in localizing papillary thyroid carcinoma (PTC) foci in patients with biochemical relapse. Papillary thyroid carcinoma has achieved biochemical recovery after appropriate treatment and had biochemical relapse in the last follow-up were included in this retrospective study. Gallium-68-FAPI and fluorine-18-fluorodeoxyglucose (68F-FDG) PET/CT were performed to detect recurrence foci. SUBJECTS AND METHODS: Biochemically relapsed patients who underwent total thyroidectomy and were diagnosed with pathologically differentiated thyroid cancer were included in our study. Gallium-68-FAPI and 18F-FDG PET/CT imaging methods were used to determine the focus of metastasis or recurrence in all patients. RESULTS: Among 29 patients enrolled to the study, pathological subgroups were papillary (n=26) and poorly differentiated (n=3) PTC. Anti-thyroglobulin (TG) antibody positivity were noted in 5 of the patients, while all 29 of them were TG positive and had been consist of three groups as follows: 2-10ng/mL (n=4), 11-300ng/mL (n=14), 301ng/mL and above (n=11). Recurrence was detected in 72.4% (n=21) and 86% (n=25) of the patients via 18F-FDG and 68Ga-FAPI, respectively. Accuracy of detection noted as 100% (5/5), 75% (3/4), and 92.9% (13/14) in groups with the anti-TG antibody positivity, TG levels of 2-10ng/mL and 11-300ng/mL, respectively, when the two imaging modalities were utilized together. Furthermore, accuracy of 68Ga-FAPI was 100% (11/11) in the group with TG levels of 301ng/mL and above, whereas accuracy of 18F-FDG was 81.8% (9/11). Lastly, median maximum standardized uptake value (SUVmax) of recurrent lesions detected by the 68Ga-FAPI (median SUVmax: 6.0) were statistically higher than the ones detected by the 18F-FDG (median SUVmax: 3.7) (P=0.002). CONCLUSION: In recurrent PTC especially in case of higher TG levels, 68Ga-FAPI can be used in patients with inconclusive 18F-FDG findings.

Is abnormal metabolism in the olfactory bulb and amygdala associated with bipolar disorder?

Accumulated evidence has demonstrated abnormal amygdala activation in bipolar disorder (BD). The olfactory bulb (OB) has vigorous connections with the amygdala. Although odor-related functions of the OB decreased during the evolutionary process, we hypothesized that an evolved OB with increased activation in emotion regulation may be one of the main factors affecting amygdala functions in BD. Our aim was to investigate metabolism in the OB and amygdala in patients with BD. Twenty-six patients diagnosed with BD according to DSM-5 diagnostic criteria were included in this cross-sectional study. Metabolism in the OB and amygdala was assessed using fluorodeoxyglucose positron emission tomography/CT in patients with BD. The OB and amygdala metabolism was compared with the patients' Z scores. Both OB and amygdala metabolic activities were significantly higher than in the controls. A positive correlation was detected between right/left amygdala metabolism and right OB metabolism (p < 0.05, r:467 and r:662, respectively). This study increased our understanding of the etiopathogenesis of BD. In BD, the main cause of hypermetabolism in the amygdala may be increased metabolism in the OB. During evolution, the OB may have assumed a dominant role in emotional processing rather than olfactory functions.

177Lu-PSMA-617 RLT in mCRPC: A single center experience, the earlier could be the better.

INTRODUCTION: Radioligand therapy which targets the prostate specific membrane antigen (PSMA) has recently considered as option in the treatment of metastatic castration resistant prostate cancer (mCRPC). The aim of this study was to evaluate the biochemical, clinical and radiological data of patients received treatment with 177Lu-PSMA-617 RLT in our clinic following the diagnosis of mCRPC, and to investigate the relationship between treatment timing and metastasis region and survival. MATERIAL AND METHODS: This is a retrospective, observational, single-center study from December 2016 to December 2019. Patients underwent 177Lu-PSMA-617 RLT with a diagnosis of mCRPC. We used the Kaplan-Meier test and the Cox regression proportional hazard test to assess survival data. RESULTS: 95 patients with an average age of 70.45 (50-85) were evaluated retrospectively. Median follow-up was 10.86 months (8.15-11.94 months) and the median lines of 177Lu-PSMA-617 RLT treatment was 4 (1-5). Median overall survival was found to be 17.03 ±â€¯5,78 months in the patients receiving the treatment at the third or lower lines while it was 10,30 ±â€¯0,93 months in patients receiving the treatment at the fourth or higher lines (p = 0.021). When evaluating patients with only bone metastasis and patients with bone and lymph node metastasis, the median overall survival was 11.46 ±â€¯0.87 months and 12.13 ±â€¯3.02 months (p = 0.445), respectively. CONCLUSION: 177Lu-PSMA-617 RLT treatment provides better survival in the treatment of patients diagnosed with mCRPC after standard treatments and received it earlier. 177Lu-PSMA-617 RLT treatment could be an effective treatment method in mCRPC patients with bone and lymph node metastasis.

Comparison of 68Ga-FAPI PET/CT and 18FDG PET/CT Modalities in Gastrointestinal System Malignancies with Peritoneal Involvement.

PURPOSE: In this study, we aimed to investigate the utilization of 68Ga-FAPI PET/CT in comparison to 18FDG PET/CT to evaluate the peritoneal involvement of the gastrointestinal malignancies alongside primary lesions and other metastatic foci. PROCEDURES: A total of 37 patients with various gastrointestinal malignancies with accompanying peritoneal involvement who underwent 68Ga-FAPI PET/CT and 18FDG PET/CT imaging between September 2020 and June 2021 were included in this retrospective study. SUVmax values of 68Ga-FAPI and 18FDG were compared according to lesion locations. Also, the lesion localization ability of both imaging was compared in patient basis. RESULTS: Of the 37 patients with peritoneal involvement (23 males and 14 females; median age, 62.8 ± 12.7 years), 35.1% (n = 13) had colorectal cancer, 37.8% (n = 14) gastric cancer, and 27.0% (n = 10) pancreaticobiliary cancer. While 45.9% of them were operated, the remaining did not have surgery. The mean time interval between two studies was 3.2 days (range: 2-6 days). The mean SUVmax value of peritoneal metastases (p < 0.001) was significantly higher with 68Ga-FAPI PET/CT compared to that with 18FDG PET/CT, as in primary lesions (p < 0.001), lymph node metastases (p = 0.006), liver metastases (p = 0.002), and bone metastases (p = 0.018). A total of 185 lesions was detected in the initial assessment with 18FDG PET/CT. Of the total lesions detected with 18FDG PET/CT, 5 of them were evaluated as benign lesions with 68Ga-FAPI PET/CT also in accordance with the reference standard. In addition to 180 lesions detected with 18FDG PET/CT, a total of 37 additional malignant lesions, 12 of which were peritoneal metastases, were detected with 68Ga-FAPI PET/CT. CONCLUSION: 68Ga-FAPI PET/CT was determined to be superior to 18FDG PET/CT in terms of detection of peritoneal involvement with high image quality as well as primary tumor and other metastatic foci. Consequently, 68Ga-FAPI PET/CT can be used as a complementary imaging modality especially for inconclusive 18FDG findings due to the lack of accuracy of 18FDG PET/CT in some of the metastatic regions, especially in the liver.

Comparison of [68Ga]-FAPI PET/CT and [18F]-FDG PET/CT in Multiple Myeloma: Clinical Experience.

OBJECTIVE: In this study, we aimed to compare [68Ga]FAPI PET/CT and [18F]FDG PET/CT imaging to detect lesions in multiple myeloma. METHODS: A total of 14 patients with multiple myeloma who underwent [68Ga]FAPI PET/CT and [18F]FDG PET/CT imaging were included in this retrospective study. SUVmax values of [68Ga]FAPI and [18F]FDG were compared according to lesion locations. Also, lesion localization ability of both imaging methods was compared on the patient basis. RESULTS: In 4 of 14 patients, [68Ga]FAPI PET/CT and [18F]FDG PET/CT have not detected any bone lesions. In 8 of the remaining 10 patients [18F]FDG PET/CT detected bone lesions but in this group, 6 patients showed more higher SUVmax values than [18F]FDG PET/CT in [68Ga]FAPI PET/CT.In contrast, 2 of 8 patients showed more higher SUVmax values than [68Ga]FAPI PET/CT in [18F]FDG PET/CT. Moreover, [68Ga]FAPI PET/CT detected bone lesions in two patients, which werenot detected by [18F]FDG PET/CT. Also, in five patients, [68Ga]FAPI PET/CT showed more bone lesions in comparison with[18F]FDG PET/CT. Only one patient, [18F]FDG PET/CT showed more bone lesions. Three extramedullary involvements were observed in the following locations: lung, presacral lymph node, and soft tissue mass lateral to the right maxillary sinus. Among these involvements, higher SUVmax values were observed in the lung and presacral lymph node with [68Ga]FAPI compared to [18F]FDG. However, the soft tissue mass showed a higher SUVmax value in [18F]FDG than [68Ga]FAPI. CONCLUSIONS: No significant superiority was observed in [68Ga]FAPI PET/CT over [18F]FDG PET/CT in patients with MM. However, [68Ga]FAPI PET/CT can be utilized as a complementary imaging method to [18F]FDG PET/CT in some settings, especially in low-[18F]FDG affinity and inconclusive cases. Considering the favorable aspects of [68Ga]FAPI PET/CT in MM, such as low background activity, absence of non-specific bone marrow, and physiological brain involvement, further studies with a larger sample size should be conducted.

Diagnostic Performance and Clinical Impact of 68Ga-PSMA-11 PET/CT Imaging in Early Relapsed Prostate Cancer After Radical Therapy: A Prospective Multicenter Study (IAEA-PSMA Study).

Biochemical recurrence (BCR) is a clinical challenge in prostate cancer (PCa) patients, as recurrence localization guides subsequent therapies. The use of PET with prostate-specific membrane antigen (PSMA) provides better accuracy than conventional imaging practice. This prospective, multicenter, international study was performed to evaluate the diagnostic performance and clinical impact of PSMA PET/CT for evaluating BCR in PCa patients in a worldwide scenario. Methods: Patients were recruited from 17 centers in 15 countries. Inclusion criteria were histopathologically proven prostate adenocarcinoma, previous primary treatment, clinically established BCR, and negative conventional imaging (CT plus bone scintigraphy) and MRI results for patients with PSA levels of 4-10 ng/mL. All patients underwent PET/CT scanning with 68Ga-PSMA-11. Images and data were centrally reviewed. Multivariate logistic regression analysis was applied to identify the independent predictors of PSMA-positive results. Variables were selected for this regression model on the basis of significant associations in the univariate analysis and previous clinical knowledge: Gleason score, the PSA level at the time of the PET scan, PSA doubling time, and primary treatment strategy. All patients were monitored for a minimum of 6 mo. Results: From a total of 1,004 patients, 77.7% were treated initially with radical prostatectomy and 22.3% were treated with radiotherapy. Overall, 65.1% had positive PSMA PET/CT results. PSMA PET/CT positivity was correlated with the Gleason score, PSA level at the time of the PET scan, PSA doubling time, and radiotherapy as the primary treatment (P < 0.001). Treatment was modified on the basis of PSMA PET/CT results in 56.8% of patients. PSMA PET/CT positivity rates were consistent and not statistically different among countries with different incomes. Conclusion: This multicenter, international, prospective trial of PSMA PET/CT confirmed its capability for detecting local and metastatic recurrence in most PCa patients in the setting of BCR. PSMA PET/CT positivity was correlated with the Gleason score, PSA level at the time of the PET scan, PSA doubling time, and radiotherapy as the primary treatment. PSMA PET/CT results led to changes in therapeutic management in more than half of the cohort. The study demonstrated the reliability and worldwide feasibility of PSMA PET/CT in the workup of PCa patients with BCR.

Superiority of 68Ga-FAPI PET/CT scan in detecting additional lesions compared to 18FDG PET/CT scan in breast cancer.

PURPOSE: We compared the ability of 68Ga-FAPI PET//CT with 18FDG PET/CT imaging techniques to detect additional lesions in breast cancer patients that may affect further chemotherapy options. METHODS: A total of 48 patients with breast cancer underwent concurrent 68Ga-FAPI-04 and 18FDG PET/CT regardless of whether they had received chemotherapy or not in the last month before imaging. Both modalities were compared according to various parameters: clinical/pathological features, number of lesions detected, activity uptake (SUVmax), and the effect on the evaluation of response to treatment in the post-chemotherapy group. RESULTS: This retrospective study included 48 patients with breast cancer (mean age 53.3 ± 11.7 years; IDC 89.6%; ILC 10.4%). In the comparison of both modalities, no statistical significance was obtained in terms of the pathological characteristics of the patients. More lesions were demonstrated in all categorized regions in 68Ga-FAPI PET/CT imaging with higher uptake values compared to 18FDG PET/CT in this study. In the treatment response evaluation of the post-chemotherapy group, 12 cases (12/24) who were evaluated as PMR, CMR, or SD according to 18FDG PET/CT results were later accepted as PD due to newly detected lesions in complementary 68Ga-FAPI PET/CT imaging and treatment of patients was managed accordingly by clinicians. CONCLUSION: It was determined that 68Ga-FAPI PET/CT was superior to 18FDG PET/CT in terms of accuracy and it was thought that 68Ga-FAPI PET/CT could be utilized as an additional complementary imaging to 18FDG PET/CT. Moreover, 68Ga-FAPI PET/CT, with its significant theranostic potential, could become a key element in predicting the pathological response of breast cancer patients in further researches.

Is SUVmax a useful marker for progression-free survival in patients with metastatic GEP-NET receiving 177Lu-DOTATATE therapy?

OBJECTIVE: The prognostic potential of pretreatment maximum standardized uptake volume (SUVmax) on gallium-68-DOTATATE was evaluated with positron emission tomography/computed tomography (68Ga-DOTATATE PET/CT) in 37 patients with G1/G2 gastroenteropancreatic neuroendocrine tumors (NET) who received peptide receptor radionuclide therapy (PRRT) with lutetium-177-[DOTAo,Tyr3] octreotate (177Lu-DOTATATE) after the failure of somatostatin analogues. METHODS: The mean and total SUVmax were used in 68Ga-DOTATATE PET/CT before 177Lu-DOTATATE treatment to assess the progression-free survival (PFS). RESULTS: The responses of the patients were evaluated as partial response in 8 (32%) patients, stable disease in 12 (48%), and progressive disease in 5 (20%). The median PFS was 18 months; longer than this threshold in 14 patients (26.0 months) and shorter in 11 (8.4 months). The mean SUVmax of metastases in the liver (34.15±17.89 vs. 14.69±9.17, P=0.004) and mean SUVmax of all body metastatic lesions (33.05±14.32 vs. 15.26±4.84, P=0.001) were higher in patientswith longer PFS. The tumor grade, the origin of the tumor, Ki67 status, and previous somatostatin treatment history were not significantly different between the two PFS groups. CONCLUSION: The pre-treatment SUVmax values of 68Ga-DOTATATE PET/CT in lesions are a potential prognostic factor for PFS in well-differentiated gastroenteropancreatic neuroendocrine tumors undergoing 177Lu-DOTATATE treatment, and could be a useful parameter for the treatment selection.

Comparison of 68Ga-DOTA-FAPI and 18FDG PET/CT imaging modalities in the detection of liver metastases in patients with gastrointestinal system cancer.

PURPOSE: We aimed to compare the diagnostic performance of PET/CT imaging performed with 68Ga-DOTA-FAPI and 18FDG in detection of liver metastases in patients with gastrointestinal system (GIS) cancer. METHODS: A total of 31 patients who underwent 68Ga-DOTA-FAPI and 18F-FDG PET/CT examinations and diagnosed with GIS cancer (15 colorectal, 9 pancreas, 4 stomach and 3 other cancers) were included in the study. The presence of liver metastasis was decided based on histopathologic diagnosis, PET/CT, other radiologic examinations or tumor biomarker findings, and both PET/CT imaging findings were compared on the patient and lesion basis. RESULTS: Of the 31 patients, 28 were found as true positive with 68Ga-DOTA-FAPI-PET/CT and 17 with 18FDG-PET/CT. Of the 98 metastatic liver lesions determined according to our diagnostic criteria, 92 were found as true positive lesions with 68Ga-DOTA-FAPI-PET/CT and 65 with 18FDG-PET/CT. There was a statistically significant difference between both imaging modalities in the patient and lesion based comparisons (p < 0.05). When semiquantitative values (SUVmax, mlr) obtained from the lesions were compared between the two imaging methods, mlr values showed statistically significant difference in all tumor subgroups (p < 0.05). CONCLUSION: It was concluded that 68Ga-DOTA-FAPI-PET/CT was superior over 18FDG-PET/CT in detection of liver metastases of GIS cancers and it can be a complementary method especially in negative cases with 18FDG-PET/CT.

The role of tumour biomarkers in choosing the appropriate positron emission tomography imaging in follow-up of medullary thyroid cancer.

INTRODUCTION: We aimed to demonstrate the importance of serum calcitonin (Ct) and carcinoembryonic-antigen (CEA) levels in the selection of appropriate positron emission tomography/computed tomography (PET/CT) modality in the follow-up of operated patients with medullary thyroid cancer. METHODS: Fourteen operated patients (8 Female, 6 Male) with MTC underwent PET/CT imaging with somatostatin (68 Ga-DOTATATE) and glucose (18 FDG) analogs due to elevated Ct or CEA at follow-up. Ct and CEA levels and both PET/CT findings were compared based on both patients and lesions. RESULTS: Positive findings were found in 10 patients with 68 Ga-DOTATATE-PET/CT and in 8 patients with 18 FDG-PET/CT, and sensitivity was found as 71.4% and 57.1% for both imaging methods, respectively (P > 0.05). Lesion could be detected with 68 Ga-DOTATATE-PET/CT in 3 patients in whom lesion could not be detected with 18 FDG-PET/CT. In one patient, whereas no pathological lesion was with 68 Ga-DOTATATE-PET/CT, lesion could be detected with 18 FDG-PET/CT in this patient. Of the total 67 lesions, 62 could be shown with 68 Ga-DOTATATE-PET/CT, while 48 lesions could be detected with 18 FDG-PET/CT (P < 0.05). A statistically significant positive correlation was found between Ct level and the number of lesions detected on the 68 Ga-DOTATATE-PET/CT, and similarly between CEA level and the number of lesions detected on the 18 FDG-PET/CT. CONCLUSIONS: It was found that 68 Ga-DOTATATE-PET/CT is superior over 18 FDG-PET/CT method in detection of recurrent disease in the follow-up of MTC, and serum Ct and CEA levels are important biomarkers in the selection of appropriate PET/CT modality.

The effect of systemic inflammation indexes and 18FDG PET metabolic parameters on survival in advanced lung adenocarcinoma.

OBJECTIVE: To determine the effect of systemic inflammation indexes and fluorine-18 fluorodeoxyglucose (18FDG) positron emission tomography (PET) metabolic parameters on survival in advanced lung adenocarcinoma. METHODS: A total of 133 patients who underwent 18FDG PET for initial staging were investigated retrospectively. Baseline patient characteristics, routine blood test results, 18FDG PET metabolic parameters, and treatment history were examined. Overall survival (OS) was demonstrated by Kaplan-Meier analysis, and the curves were compared by the log-rank test. Systemic inflammation response index (SIRI) was defined as neutrophil x monocyte/lymphocyte count. RESULTS: Lymphocyte/monocyte ratio (LMR) and SIRI were found to be significant for OS. The cutoff point was 2.25 for LMR. Median OS was 8 months for ⩽2.25 and 14 months for >2.25 (p = 0.005). For SIRI, the cutoff point was 2. SIRI ⩽2 was associated with a median OS of 16 months compared to 10 months for patients with SIRI >2 (p = 0.043). Maximum of standardized uptake value, total lesion glycolysis, and metabolic tumor volume were not found to be significant for OS (p = 0.225, p = 0.061, p = 0.355, respectively). No correlation was found between inflammatory indexes and PET metabolic parameters. CONCLUSION: Age and LMR parameters were prognostic for survival in Cox regression analysis. There was no correlation between 18FDG PET parameters and inflammatory indexes.

Long-term survival with transarterial chemoembolization and radioembolization in a patient with cancers of unknown primary.

Cancers of unknown primary (CUP) are histologically proven metastatic malignant tumors without an identified primary site before treatment. The common characteristics are early dissemination, lower response to chemotherapy and poor prognosis with short life expectancy. Treatment was directed according to the presence of localized or disseminated disease. The most frequent site of metastasis is the liver, which is a suitable target organ for arterial-directed therapies. We report a case of 53-year-old woman who was diagnosed with CUP and suspected with intracellular cholangiocellular carcinoma (ICC), presented with a very large, unresectable, chemotherapy-refractory hepatic mass and treated with transarterial chemoembolization and transarterial radioembolization and surprisingly followed for 48 months with minimally progressive and stable disease. Arterial-directed therapies, an important therapeutic option in unresectable liver tumors, can provide survival benefit even for ICC and CUP which are very large in size.

Relationship between reticuloendothelial systems' FDG uptake level and clinicopathological features in patient with invasive ductal breast cancer.

PURPOSE: The reticuloendothelial system (RES) is a part of the immune system and plays a major role in the protection of against diseases. We thought that FDG-PET/CT may show the degree of systemic immune response induced with malignancy in the organs with the high RES activity. Our objective is to investigate FDG uptake levels of high RES activity organs (liver, spleen, bone marrow) in invasive ductal breast cancer and to evaluate the association with the clinicopathological features. METHODS: In the present study, 193 patients with invasive ductal breast cancer who performed FDG-PET/CT were categorized according to the clinicopathological features including age, tumor size, axillary nodal status, histological grade, the presence of lymphavascular invasion, receptor status, Ki-67 proliferation index and biological subgroup. Also, a control group of 100 subjects were identified for comparison with breast cancer patients. We analyzed the relation of FDG uptake levels in high RES activity organs and clinicopathological features in patients. RESULTS: There was a statistically significant difference of SUVmax of the liver, spleen, and bone marrow between cancer and control groups (P < 0.0001). We found that high SUVmax in liver, spleen and bone marrow were significantly correlated with worse prognostic clinicopathological features in patient with invasive ductal breast cancer. CONCLUSIONS: FDG uptake level in high RES activity organs is associated with the presence of tumor, and also directly relating clinicopathological features for patients with invasive ductal breast cancer.

Contribution of nonattenuation-corrected images on FDG-PET/CT in the assessment of solitary pulmonary nodules.

In this study, we aim to determine the diagnostic performance of nonattenuation-corrected (NAC) and attenuation-corrected (AC) FDG-PET/CT images in the assessment of solitary pulmonary nodule (SPN). We reviewed the images of 41 patients who underwent FDG-PET/CT to diagnose SPNs. The visual analysis of FDG uptake intensity in SPN on AC and NAC PET images was made using a four-point score from 1 to 4 on both AC and NAC PET images. The cutoff value of SUVmax and visual uptake scores for malignancy were defined as ≥2.5 and ≥3, respectively. The significant visual uptake (≥2 visual point score) on AC and NAC PET images was considered to be positive 18F-FDG PET findings for lesion detectability. The sensitivity, specificity and diagnostic accuracy were calculated for AC and NAC PET images. Based on the histopathology and imaging data, 22 of the SPNs (54 %) were malignant and 19 of them (46 %) were benign. The sensitivity and NPV were found to be 100 % in the detection of SPNs for AC and NAC PET images. For all SPNs and SPNs ≤2 cm, NAC PET image had a higher diagnostic performance for the SPN characterization as malignant or benign, when compared with AC PET image. The success rates of AC and NAC PET images were found to be similar for the detection of SPNs. NAC PET image had a higher diagnostic performance for the SPN characterization. It is thought that NAC PET image may provide additional contributions for characterization of SPNs.

Lu-177 labelled peptide treatment for radioiodine refractory differentiated thyroid carcinoma.

Differentiated thyroid carcinoma (DTC) has good prognosis but 5% of the patients already have distant metastasis at the diagnosis. Tumour cells can lose their iodine uptake ability and enter a state of dedifferentiation. Treatment for differentiated thyroid carcinoma that is not suitable for the local surgery and unresponsive to radioactive iodine uptake is not always easy for physicians. We present a case of a 64-year-old man who had total thyroidectomy surgery and central lymph node dissection with diagnosis of multinodular goitre disease. Histopathological evaluation was papillary thyroid cancer with tall cell variant. Treatment using 150 mCi radioiodine was administered to the patient three times but could not effect a cure. We performed Ga-68 labelled DOTATE (synthetic somatostatin analogue peptide). This provided a good outcome. As evident from our case, Lu-177 radionuclide labelled synthetic somatostatin analogue peptides have therapeutic effect on radioiodine refractory DTC, as an alternative treatment modality.