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.

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.

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 ± 5,78 months in the patients receiving the treatment at the third or lower lines while it was 10,30 ± 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 ± 0.87 months and 12.13 ± 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 [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.

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 (SUV_max), 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-[DOTA^o,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.

Diagnostic performance and clinical impact of 68Ga-PSMA-11 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.

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.

Paraoxonase and arylesterase levels in autoimmune thyroid diseases

OBJECTIVE

The aim of this study was to evaluate serum paraoxonase-1 (PON1) activity and its association with oxidative stress in autoimmune thyroid disease (AITD).

METHODS

A total of 50 patients with AITD, including 25 with Hashimoto's thyroiditis and 25 with Graves' disease were enrolled. The control group comprised 27 healthy subjects. Blood samples were obtained in the euthyroid period and 3 months after initiation of medical treatment. Serum samples from patients with AITD and the healthy control group were analyzed for basal PON1, salt-stimulated PON1, and arylesterase (ARE) activities, along with lipid hydroperoxide (LOOH) and total free sulfhydryl (-SH) levels.

RESULTS

Serum PON1 activities and -SH levels were significantly lower (P < 0.001, for each), whereas LOOH levels were significantly higher (P < 0.001, for each) in patients with AITD, compared to the control group. We observed no significant differences in ARE levels between the patient and healthy control groups (P > 0.05). PON1 activity was positively correlated with -SH (r = 0.522, P < 0.001) and negatively correlated with LOOH (r = -0.487, P < 0.001). PON1 phenotype distribution of the subjects was not significantly different among the three groups (P = 0.961).

CONCLUSIONS

Serum PON1 activity is decreased in patients with AITD, and correlated positively with -SH, a well-known antioxidant, and negatively with LOOH, an index of lipid oxidation.

Clinical significance of incidental FDG uptake in the prostate gland detected by PET/CT

The value of FDG-positron emission tomography/computed tomography (PET/CT) for detecting prostate cancer is unknown. We aimed to investigate the clinical value of incidental prostate FDG uptake on PET/CT scans. We reviewed 6128 male patients who underwent FDG-PET/CT scans and selected cases that reported hypermetabolic lesion in the prostate. The patients who have prior history of prostate carcinoma or prostate surgery were excluded from the study. We have analyzed the correlation between PET/CT findings and serum prostate-specific antigen (PSA) levels, imaging (USG), urological examinations and biopsy. Incidental 18F-FDG uptake of the prostate gland was observed in 79 patients (1.3%). While sixteen of them were excluded due to inadequate clinical data, the remaining 63 patients were included for further analysis. The patients were divided into two groups; 8 patients (12.7%) in the malignant group and 55 patients (87.3%) in the benign group. The SUVmax values were not significantly different between the two groups. In 6 (75%) patients with prostate cancer, FDG uptake was observed focally in the peripheral zone of the prostate glands. There was no significant correlation between the SUVmax and the PSA levels. Incidental 18F-FDG uptake in the prostate gland is a rare condition, but a substantial portion of it is associated with the cancer. Benign and malignant lesions of the prostate gland in FDG-PET/CT imaging could not be reliably distinguished. The peripheral focally FDG uptake of prostate glands should be further examined with the clinical and labaratory evaluations.

Evaluation of conventional imaging techniques on preoperative localization in primary hyperparathyroidism

We aimed to evaluate the diagnostic and preoperative localization capacity of 99mTc methoxyisobutylnitrile (MIBI) parathyroid scintigraphy and ultrasonography (USG) in enlarged parathyroid glands in the primary hyperparathyroidism (pHPT) as well as the relationship between the success rate of these techniques and biochemical values. In this study, we retrospectively evaluated 39 patients with clinical and biological evidence of pHPT who referred to the university hospital for MIBI parathyroid scintigraphy. Patients were examined with USG and double-phase MIBI parathyroid scintigraphy for the detection of enlarged parathyroid glands. Preoperative serum intact parathyroid hormone (iPTH) levels, calcium (Ca), phosphate and alkaline phosphatase measurements were obtained. A total of 45 parathyroid lesions in 39 patients were reviewed. Thirty-four patients had a single adenoma and 5 patients with multi-gland disease had 11 abnormal parathyroid glands including three adenomas, whereas the remaining 8 glands showed hyperplasia. The overall sensitivities of MIBI parathyroid scintigraphy, USG and combined techniques were 85.3%, 72.5% and 90.4%, respectively; the positive predictive values (PPV) were 89.7%, 85.2% and 92.6%, respectively. The most successful approach for detection of enlarged parathyroid glands in hyperparathyroidism is the concurrent application of USG and MIBI parathyroid scintigraphy modalities. The concomitancy of thyroid diseases decreases the sensitivity of both MIBI parathyroid scintigraphy and USG in enlarged parathyroid glands.

F-18 FDG PET/CT imaging in the diagnostic work-up of thyroid cancer patients with high serum thyroglobulin, negative I-131 whole body scan and suppressed thyrotropin: 8-year experience

OBJECTIVE

Fluorodeoxyglucose positron emission tomography/computed tomography imaging in the follow-up of patients with differentiated thyroid carcinoma who have high serum thyroglobulin, negative iodine-131 whole body scan and suppressed thyrotropin.

PATIENTS AND METHODS

A total of 90 patients (31 male and 59 female) with differentiated thyroid carcinoma who have high serum thyroglobulin and negative iodine-131 whole body scan were included in the study between July 2006 and March 2014. All patients had undergone surgery (total thyroidectomy ± lymph node dissection) followed by iodine-131 ablation. Of the patients, 82 had papillary thyroid carcinoma and 8 follicular thyroid carcinoma. Serum thyrotropin was suppressed (< 2 μ IU/ml) during the Fluor-18 fluorodeoxyglucose positron emission tomography/computed tomography imaging procedure.

RESULTS

The overall sensitivity of fluor-18 fluorodeoxyglucose positron emission tomography/computed tomography imaging in the detection of metastasis of differentiated thyroid cancer was 84.8%, the specificity 79.1%, respectively. The sensitivity and specificity of fluor-18 fluorodeoxyglucose positron emission tomography/computed tomography imaging in classic type of papillary cancer was 83.3% and 54.5%, respectively. The corresponding figures for the tall cell variant was 85.7% and 87.5%, respectively. The difference between the two histological subtypes was statistically significant (p < 0.05).

CONCLUSIONS

Our results suggest that fluor-18 fluorodeoxyglucose positron emission tomography/computed tomography imaging could be a valuable test for the routine follow-up of patients with differentiated thyroid carcinoma.

Utility of F-18 fluorodeoxyglucose posıtron emıssıon tomography/computed ın carcınoma of unknown primary

Carcinoma of unknown primary (CUP) is a heterogeneous group of tumors with various clinical features causing diagnostic and therapeutic challenges. The aim of this study was to evaluate the ability of F-18 FDG PET/CT for localizing the primary tumor, disclosing additional metastases, and changing the treatment in patients with CUP. One hundred and twelve metastatic patients (female = 40, male = 72, median age = 60.5 years) in whom conventional diagnostic work-up failed to disclose the primary tumor were included in the study. F-18 FDG PET/CT imaging was performed in a standard protocol (patient supine, arms on patient's side, vertex to thigh, 369.3 MBq (296-444 MBq) F-18 FDG, a 60-minute uptake period, 6-7 bed position). Histopathology was taken as the only reference standard. F-18 FDG PET/CT correctly detected primary tumor in 37 of 112 (33.03%) patients. The most common site of primary tumor detected by F-18 FDG PET/CT was lung (n = 18), which was followed by nasopharynx (n = 7), pancreas (n = 5), tonsil (n = 2), breast (n = 2), thyroid (n = 1), uterus (n = 1) and colon/rectum (n = 1). F-18 FDG PET/CT imaging disclosed additional previously undetected metastases in 32 (28.5%) and changed the treatment in 33 (29.4%) of 112 patients. There were false positive F-18 FDG PET/CT results in 21 (18.5%) patients. F-18 FDG PET/CT is able to disclose the primary tumor, disclose new metatases and change the treatment in about one third of patients with CUP.

Is (99m)Tc-MDP whole body bone scintigraphy adjuvant to (18)F-FDG-PET for the detection of skeletal metastases?

PURPOSE

Due to the fact that fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG-PET/CT) and technetium-99m-methylenediphosphonate ((99m)Tc-MDP) whole body scans identify bone metastases by different mechanisms, i.e. by using glucose metabolism and osteoblastic response in the bone, respectively, it can be expected that there may be some differences between these two methods in the number of lesions identified. The aim of this study was to compare the sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) in detecting bone metastases between (18)F-FDG-PET/CT and conventional (99m)Tc-MDP whole body scans.

METHODS

Between 2006-2009, 121 patients with malignancies (62 male and 59 female, mean age 59.3±10.8 years, range 37-84) were examined with (18)F-FDG-PET/CT and conventional (99)Tc-MDP whole-body scans for detection of bone metastases.

RESULTS

For (18)F-FDG-PET/CT and for (99m)TC-MDP, sensitivity, specificity, accuracy, PPV and NPV for detecting all studied bone metastases were 88.3, 83.6, 86.7, 91.7, 77.8% and 91.7, 71.0, 84.9, 86.6, 80.8%, respectively. For bone metastases of breast and lung cancers, the specificity and accuracy of PET/CT was higher than that of bone scintigraphy. On the other hand, the sensitivity of bone scintigraphy was higher than PET/CT in breast and lung cancers groups and all patients. In the detection of osteolytic and osteosclerotic metastases no difference was found between the two methods, while for osteolytic lesions the mean standardized uptake value (SUV) max was higher than for osteosclerotic lesions.

CONCLUSION

For the detection of bone metastases the specificity and accuracy of (18)F-FDG-PET/CT were higher compared to bone scintigraphy, while the sensitivity was lower. It is the opinion of the authors that both studies are complementary to final diagnosis.

Lung metastases in patients with differentiated thyroid carcinoma and evaluation of response to radioiodine therapy

INTRODUCTION

The most common site of metastases in differentiated thyroid carcinomas is the lungs. In our study, we aimed to determine the ratios of lung metastases in patients with differentiated thyroid carcinoma and response to radioiodine therapy.

MATERIAL AND METHODS

A total of 542 patients with differentiated thyroid carcinoma who were admitted to our clinic were included in the study. High doses of (131)I were administered to the patients with lung metastases. Response to therapy were evaluated with (131)I scans and stimulated serum Tg levels were examined at least 6 months after therapy.

RESULTS

Lung metastases were detected in 17 (3.1%) of 542 patients with differentiated thyroid carcinoma. Of these patients to whom high doses of (131)I therapy were administered, complete response to therapy was obtained in 5 (29.4%), partial response was obtained in 3 (17.6%) and no response could be obtained in 9 (53%) patients.

CONCLUSION

Although lung metastases from differentiated thyroid carcinomas are rare, those are more common in advanced ages and in males. High doses of (131)I therapy may be partially beneficial in these patients. Thus repetition of therapy is frequently required.