PRIMARY HYPERPARATHYROIDISM AND SERUM CALCIUM IN BREAST CANCER PATIENTS EVALUATED FOR LOW BONE MASS - A SINGLE CENTER EXPERIENCE.

The bone health guidelines for breast cancer (BC) patients recommend bone mineral density (BMD) testing. Patients with low BMD and elevated serum calcium levels (SCLs) are further evaluated for primary hyperparathyroidism (PHPT). We aimed to determine the prevalence of PHPT in treated BC patients with low BMD and analyze the association of SCLs with histopathologic tumor features and cancer treatment. This retrospective study included postmenopausal BC patients examined at Osteoporosis Clinic between 2013 and 2020. Clinical and BMD data were collected from patient medical records. Patients with biochemical suspicion of PHPT underwent standard parathyroid imaging procedures. Nine out of 137 (6.6%) patients were diagnosed with PHPT; 8/9 patients underwent parathyroidectomy and one patient was advised to follow-up. Among the rest of 128 non-PHPT patients, higher SCLs showed a trend of positive association with higher tumor grade and axillary lymph node involvement, and received immunotherapy, although without statistical significance. We found a higher prevalence of PHPT in treated BC patients compared to the general population. Higher SCLs show a trend of positive correlation with some more aggressive histopathologic tumor features and with immunotherapy. The results of this study suggest that assessment of SCLs should be routinely performed to rule out PHPT in treated BC patients with low BMD.

Somatostatin receptor based hybrid imaging in sarcoidosis.

Several diagnostic imaging methodologies are available for the clinical evaluation of sarcoidosis, but all have their limitations. FDG PET/CT is frequently used, but this technique does not provide optimal results in all cases. Novel radiopharmaceuticals aimed at other disease targets may be helpful, particularly in cardiac sarcoidosis when FDG PET/CT has a low diagnostic accuracy, due to difficulties in preparing the patients who should use a specific diet combined with prolonged fasting. 68Ga-labeled somatostatin based receptor hybrid imaging is a potential alternative to FDG PET/CT. This short communication provides a rapid overview of initial findings concerning the application of 68Ga-labeled somatostatin based receptor hybrid imaging in the diagnosis of (cardiac) sarcoidosis activity.

Other PET tracers for neuroendocrine tumors.

In this article the applicability of (124)I-MIBG and (11)C-5-HTP PET for the detection of abdominal gastro-enteropancreatic neuroendocrine tumors is discussed. (124)I-MIBG is a positron-emitting variant of (123)I-MIBG and therefore suited for PET imaging. Due to the better intrinsic characteristics of PET, (124)I-MIBG PET has a higher spatial resolution than (123)I-MIBG and may therefore lead to better lesion detection in patients with neuroblastoma and pheochromocytoma. Research is ongoing to develop (18)F-labeled analogues and to assess its place in staging patients with gastro-enteropancreatic neuroendocrine tumors when compared with (18)F-FDOPA and (68)Ga-somatostatin PET analogues.

Clinical relevance of 18F-FDG PET and 18F-DOPA PET in recurrent medullary thyroid carcinoma.

UNLABELLED: The transition from stable to progressive disease is unpredictable in patients with biochemical evidence of medullary thyroid carcinoma (MTC). Calcitonin and carcinoembryonic antigen (CEA) doubling times are currently the most reliable markers for progression, but for accurate determination, serial measurements, which need time, are required. We compared (18)F-FDG PET and (18)F-dihydroxyphenylanaline ((18)F-DOPA) PET with biochemical parameters and survival to assess whether these imaging modalities could be of value in detecting progressive disease. METHODS: We evaluated the outcome of (18)F-FDG PET or (18)F-DOPA PET with calcitonin and CEA doubling times in 47 MTC patients. A subgroup of patients was included in the whole metabolic burden (WBMTB) analysis, with determination of standardized uptake values and number of lesions. WBMTB of (18)F-DOPA PET and (18)F-FDG PET was compared with biochemical parameters. Furthermore, survival was compared with (18)F-DOPA PET or (18)F-FDG PET positivity. RESULTS: Doubling times were available for 38 of 40 patients undergoing (18)F-FDG PET. There was a significant correlation with (18)F-FDG PET positivity. Doubling times were less than 24 mo in 77% (n = 10/13) of (18)F-FDG PET-positive patients, whereas 88% (n = 22/25) of (18)F-FDG PET-negative patients had doubling times greater than 24 mo (P < 0.001). Between doubling times and (18)F-DOPA PET positivity, no significant correlation existed. (18)F-DOPA PET detected significantly more lesions (75%, 56/75) than did (18)F-FDG PET (47%, 35/75) in the 21 patients included in WBMTB analysis (P = 0.009). Calcitonin and CEA levels correlated significantly with WBMTB on (18)F-DOPA PET, but doubling times did not. (18)F-FDG PET positivity was a more important indicator for poor survival in patients for whom both scans were obtained. CONCLUSION: (18)F-FDG PET is superior in detecting patients with biochemical progressive disease and identifying patients with poor survival. Although (18)F-DOPA PET has less prognostic value, it can more accurately assess the extent of the disease in patients with residual MTC. Hence, both scans are informative about tumor localization and behavior. On the basis of these results, we designed a clinical flow diagram for general practice in detecting recurrent MTC.

Total 18F-dopa PET tumour uptake reflects metabolic endocrine tumour activity in patients with a carcinoid tumour.

PURPOSE: Positron emission tomography (PET) using 6-[18F]fluoro-L-dihydroxyphenylalanine (18F-dopa) has an excellent sensitivity to detect carcinoid tumour lesions. 18F-dopa tumour uptake and the levels of biochemical tumour markers are mediated by tumour endocrine metabolic activity. We evaluated whether total 18F-dopa tumour uptake on PET, defined as whole-body metabolic tumour burden (WBMTB), reflects tumour load per patient, as measured with tumour markers. METHODS: Seventy-seven consecutive carcinoid patients who underwent an 18F-dopa PET scan in two previously published studies were analysed. For all tumour lesions mean standardised uptake values (SUVs) at 40% of the maximal SUV and tumour volume on 18F-dopa PET were determined and multiplied to calculate a metabolic burden per lesion. WBMTB was the sum of the metabolic burden of all individual lesions per patient. The 24-h urinary serotonin, urine and plasma 5-hydroxindoleacetic acid (5-HIAA), catecholamines (nor)epinephrine, dopamine and their metabolites, measured in urine and plasma, and serum chromogranin A served as tumour markers. RESULTS: All but 1 were evaluable for WBMTB; 74 patients had metastatic disease. 18F-dopa PET detected 979 lesions. SUVmax on 18F-dopa PET varied up to 29-fold between individual lesions within the same patients. WBMTB correlated with urinary serotonin (r=0.51) and urinary and plasma 5-HIAA (r=0.78 and 0.66). WBMTB also correlated with urinary norepinephrine, epinephrine, dopamine and plasma dopamine, but not with serum chromogranin A. CONCLUSION: Tumour load per patient measured with 18F-dopa PET correlates with tumour markers of the serotonin and catecholamine pathway in urine and plasma in carcinoid patients, reflecting metabolic tumour activity.

Combining 6-fluoro-[18F]l-dihydroxyphenylalanine and [18F]fluoro-2-deoxy-d-glucose positron emission tomography for distinction of non-carcinoid malignancies in carcinoid patients.

AIM: Carcinoid patients frequently develop a second primary malignancy (SPM), which can deserve full treatment. Distinguishing a SPM from carcinoid lesions is therefore important. Differentiation can be achieved using the difference in uptake between different positron emission tomography (PET) tracers. METHODS AND RESULTS: Between January 2005 and August 2008, 105 carcinoid patients were seen at the Department of Medical Oncology for treatment and follow-up. We identified 3 patients who presented with a new SPM in whom differentiation between carcinoid lesions and the SPM was guided by functional imaging of the catecholamine pathway with 6-fluoro-[(18)F]l-dihydroxyphenylalanine ((18)F-DOPA) PET and [(18)F]fluoro-2-deoxy-d-glucose ((18)F-FDG) PET as radiotracer for the glucose metabolism. All 3 patients had metastatic carcinoid disease and localised adenocarcinoma based on the PET-scans. For the adenocarcinoma they received curative treatment. CONCLUSION: The difference in uptake between these PET techniques can be used for decision making when a primary or metastatic SPM is suspected.

111In-octreotide is superior to 123I-metaiodobenzylguanidine for scintigraphic detection of head and neck paragangliomas.

UNLABELLED: In this study, we evaluated the diagnostic yield of somatostatin receptor scintigraphy (SRS), I-metaiodobenzylguanidine (MIBG) scintigraphy, and morphologic imaging (CT or MRI) in patients with head and neck paragangliomas. METHODS: In a university hospital setting, patients considered to have head and neck paraganglioma were referred to the outpatient endocrinology department and underwent CT or MRI, SRS, and MIBG imaging. For validation, we used a composite reference standard consisting of clinical and histologic data and CT or MRI, with which SRS and MIBG imaging were compared. Urinary metanephrine and normetanephrine measurements were also obtained. RESULTS: Twenty-nine consecutively referred patients (17 women and 12 men) were included and were found to have paraganglioma. Both morphologic and SRS were positive in 27 patients (sensitivity, 93%, and 95% confidence interval [CI], 77%-98%, compared with the composite reference standard), whereas MIBG was positive in only 13 patients (44%; 95% CI, 23%-61%) (P < 0.001, compared with SRS). On a lesion-based analysis, morphologic imaging detected 31 lesions (sensitivity, 82%; 95% CI, 65%-92%), SRS detected 34 (89%; 95% CI, 75%-97%), and MIBG detected 15 (42%; 95% CI, 26%-59%). SRS was superior to MIBG (P = 0.001). With SRS, a previously unknown carcinoid tumor was detected in 1 patient, and a carcinoid was suspected in another patient. MIBG detected an additional adrenal pheochromocytoma in 1 patient. Urinary metanephrine or normetanephrine excretion was elevated in 6 patients. The number of lesions on SRS and MIBG per patient correlated with the levels of abnormal metanephrine or normetanephrine excretion (P = 0.005 and P = 0.02, respectively). CONCLUSION: SRS was superior to MIBG in patients with highly suspected head and neck paraganglioma.

6-L-18F-fluorodihydroxyphenylalanine PET in neuroendocrine tumors: basic aspects and emerging clinical applications.

In recent years, 6-l-18F-fluorodihydroxyphenylalanine (18F-DOPA) PET has emerged as a new diagnostic tool for the imaging of neuroendocrine tumors. This application is based on the unique property of neuroendocrine tumors to produce and secrete various substances, a process that requires the uptake of metabolic precursors, which leads to the uptake of 18F-DOPA. This nonsystematic review first describes basic aspects of 18F-DOPA imaging, including radiosynthesis, factors involved in tracer uptake, and various aspects of metabolism and imaging. Subsequently, this review provides an overview of current clinical applications in neuroendocrine tumors, including carcinoid tumors, pancreatic islet cell tumors, pheochromocytoma, paraganglioma, medullary thyroid cancer, hyperinsulinism, and various other clinical entities. The application of PET/CT in carcinoid tumors has unsurpassed sensitivity. In medullary thyroid cancer, pheochromocytoma, and hyperinsulinism, results are also excellent and contribute significantly to clinical management. In the remaining conditions, the initial experience with 18F-DOPA PET indicates that it seems to be less valuable, but further study is required.