False iodine-131 MIBG scintigraphy findings in adrenal tumors: correlation with MR imaging

AbstractIn this study, we report our experience regarding the occurrence of false radionuclide findings in adrenal iodine-131 MIBG scintigraphy. We present a total of five patients in which nuclear images were false negative or positive in three and two cases, respectively, according to the standard radionuclide established criteria. In particular, the three cases of false-negative MIBG images consisted of two patients with necrotic or cystic pheochromocytomas (Cases 1 and 3) and a patient with a small pheochromocytoma (Case 2); the two cases of false-positive MIBG imaging consisted of a patient with an adenoma showing intense tracer uptake and of a large primary necrotic carcinoma with heterogeneous tracer concentration

Imaging characterization of non-hypersecreting adrenal masses. Comparison between MR and radionuclide techniques.

AIM: In patients with non-hypersecreting adrenal masses, tumor characterization is clinically relevant to establish the appropriate treatment planning. The aim of this study was to comparatively characterize such adrenal lesions using MR and radionuclide techniques. METHODS: Thirty patients with non-hypersecreting unilateral adrenal tumors underwent both MR and adrenal scintigraphy. MR was performed using SE T1- (pre- and post-gadolinium DTPA) and T2-weighted images as well as in- and out-phase chemical-shift imaging (CSI). MR qualitative and quantitative (signal intensity ratios) evaluation was performed. Radionuclide studies consisted of iodine-131 nor-cholesterol (n=20), iodine-131 MIBG (n=15) and fluorine-18 FDG PET (n=11) scans. Histology (n=16), biopsy (n=3) or clinical-imaging follow-up (n=11) demomstrated 13 adenomas, 3 cysts, 2 myelolipomas, 4 pheochromocytomas (pheos), 4 carcinomas, 1 sarcoma and 3 metastases. Comparative imaging analysis was focused on adenomas, pheos and malignant tumors. RESULTS: Qualitative MR evaluation showed: signal T2-hyperintensity in 46% of adenomas and in 100% of pheos and malignant tumors, no gadolinium enhancement in 92% of adenomas and definite signal intensity loss on CSI in 100% of such tumor lesions, gadolinium enhancement in 100% of pheos and in 63% of malignancies and no absolute change of signal intensity on CSI in 100% of both pheos and malignancies. Quantitative MR analysis demonstrated: significantly higher signal T2-hyperintensity of pheos compared to adenomas and malignancies as well as significantly higher enhancement after gadolinium in pheos compared to adenomas and malignancies (p<0.03). Radionuclide studies showed significantly increased nor-cholesterol uptake only in adenomas (n=13), significant MIBG accumulation only in pheos (n=4) and FDG activity only in malignant adrenal lesions (n=8). CONCLUSION: MR techniques may provide some presumptive criteria to characterize non-hypersecreting adrenal masses, such as no gadolinium enhancement and definite signal intensity loss on CSI in adenomas or quantitatively measured T2-hyperintensity and gadolinium enhancement in pheos. On the other hand, radionuclide modalities offer more specific findings in this setting since nor-cholesterol and MIBG scans are respectively able to reveal benign tumors such as adenoma and pheochromocytoma, while FDG imaging allows identification of malignant adrenal lesions. Adrenal scintigraphy is recommended in those patients, when MR images are uncertain or inconclusive

Insights into Myocardial Perfusion PET Imaging: the Coronary Flow Capacity

Purpose of Review The present work summarizes the clinical relevance of coronary flow capacity (CFC) with an eye on future perspectives. Recent findings CFC concept has been recently introduced providing a comprehensive framework for coronary physiology evaluation. Summary It has been widely demonstrated that coronary artery disease (CAD) is a complex disease with a multifactorial etiology resulting from different pathogenic mechanisms. Cardiac positron emission tomography (PET) currently represents the gold standard for CAD assessment, providing absolute myocardial perfusion data including coronary flow reserve (CFR), calculated as the ratio of hyperemic to rest absolute myocardial blood flows. CFC can be obtained from dynamic PET images by plotting the primary stress perfusion data and CFR values for each pixel on a graph of predefined exact ranges. The routine evaluation of this parameter may add diagnostic and prognostic value to clinical and conventional imaging data

Cardiac hybrid imaging: novel tracers for novel targets

Non-invasive cardiac imaging has explored enormous advances in the last few decades. In particular, hybrid imaging represents the fusion of information from multiple imaging modalities, allowing to provide a more comprehensive dataset compared to traditional imaging techniques in patients with cardiovascular diseases. The complementary anatomical, functional and molecular information provided by hybrid systems are able to simplify the evaluation procedure of various pathologies in a routine clinical setting. The diagnostic capability of hybrid imaging modalities can be further enhanced by introducing novel and specific imaging biomarkers. The aim of this review is to cover the most recent advancements in radiotracers development for SPECT/CT, PET/CT, and PET/MRI for cardiovascular diseases

The diagnostic role of total-body 18F-FDG PET/CT in patients with multiple tumors: a report of the association of thyroid cancer with lung or renal tumors

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Diagnosis, Management and Theragnostic Approach of Gastro-Entero-Pancreatic Neuroendocrine Neoplasms

Abstract: Gastro-entero-pancreatic neuroendocrine neoplasms (GEP-NENs) constitute an ideal target for radiolabeled somatostatin analogs. The theragnostic approach is able to combine diagnosis and therapy by the identification of a molecular target that can be diagnosed and treated with the same radiolabeled compound. During the last years, advances in functional imaging with the introduction of somatostatin analogs and peptide receptor radionuclide therapy, have improved the diagnosis and treatment of GEP-NENs. Moreover, PET/CT imaging with 18F-FDG represents a complementary tool for prognostic evaluation of patients with GEP-NENs. In the field of personalized medicine, the theragnostic approach has emerged as a promising tool in diagnosis and management of patients with GEP-NENs. The aim of this review is to summarize the current evidence on diagnosis and management of patients with GEP-NENs, focusing on the theragnostic approach

Whole-body radioiodine effective half-life in patients with differentiated thyroid cancer

Background: Radioactive 131I (RAI) therapy is used in patients with differentiated thyroid cancer (DTC) after total thyroidectomy for remnant ablation, adjuvant treatment or treatment of persistent disease. 131I retention data, which are used to indicate the time at which a 131I treated DTC patient can be released from the hospital, may bring some insights regarding clinical factors that prolong the length of hospitalization. The aim of this study was to investigate the 131I whole-body retention in DTC patients during 131I therapy. Methods: We monitored 166 DTC patients to follow the 131I whole-body retention during 131I therapy with a radioactivity detector fixed on the ceiling of each protected room. A linear regression fit permitted us to estimate the whole-body 131I effective half-life in each patient, and a relationship was sought between patients’ clinical characteristics and whole-body effective 131I half-life. Results: The effective 131I half-life ranged from 4.08 to 56.4 h. At multivariable analysis, longer effective 131I half-life was related to older age and extensive extra-thyroid disease. Conclusions: 131I effective half-life during 131I treatment in DTC patients is highly variable among patients and is significantly longer in older and in patients with RAI uptake in large thyroid remnants or in extrathyroidal disease that significantly prolongs the whole-body retention of 131I

Initial Testing of an Approximated, Fast Calculation Procedure for Personalized Dosimetry in Radionuclide Therapy Based on Planar Whole-Body Scan and Monte-Carlo Specific Dose Rates from the OpenDose Project

Individualized dosimetry in nuclear medicine is currently at least advisable in order to obtain the best risk–benefit balance in terms of the maximal dose to lesions and under-threshold doses to radiosensitive organs. This article aims to propose a procedure for fast dosimetric calculations based on planar whole-body scintigraphy (WBS) images and developed to be employed in everyday clinical practice. Methods: For simplicity and legacy reasons, the method is based on planar imaging dosimetry, complemented with some assumptions on the radiopharmaceutical kinetics empirically derived from single-photon emission tomography/computed tomography (SPECT/CT) image analysis. The idea is to exploit a rough estimate of the time-integrated activity as has been suggested for SPECT/CT dosimetry but using planar images. The resulting further reduction in dose estimation accuracy is moderated by the use of a high-precision Monte-Carlo S-factor, such as those available within the OpenDose project. Results: We moved the problem of individualized dosimetry to a transformed space where comparing doses was imparted to the ICRP Average Male/Female computational phantom, resulting from an activity distribution related to patient’s pharmaceutical uptake. This is a fast method for the personalized dosimetric evaluation of radionuclide therapy, bearing in mind that the resulting doses are meaningful in comparison with thresholds calculated in the same framework. Conclusion: The simplified scheme proposed here can help the community, or even the single physician, establish a quantitative guide-for-the-eye approach to individualized dosimetry

Bone demineralization and vertebral fractures in endogenous cortisol excess: role of disease etiology and gonadal status

INTRODUCTION: The effects of endogenous cortisol (F) excess on bone mass and vertebral fractures have still not been thoroughly investigated. The aim of this cross-sectional case-control study was to investigate factors influencing bone demineralization and vertebral fractures in different conditions of F excess, i.e. Cushing's disease and adrenal and ectopic Cushing's syndrome. MATERIALS AND METHODS: Eighty consecutive patients and 80 controls were prospectively enrolled: 37 patients (21 females) with pituitary ACTH-secreting adenoma, 18 (14 females) with adrenocortical adenoma, 15 (11 females) with adrenal carcinoma of mixed secretion, and 10 (three females) with ectopic ACTH secretion. The groups had similar age. At diagnosis, bone mineral density (BMD) was determined by the dual-energy x-ray absorptiometry technique at the lumbar spine (L1-L4) and femoral neck; vertebral fractures were investigated by standard spinal radiographs. RESULTS: When comparing the groups with different etiology of F excess, the patients with ectopic ACTH secretion had higher F and lower BMD values than the other subgroups. Morning F (P = 0.03) and testosterone levels (P = 0.04) correlated with lumbar BMD. Vertebral fractures were found in 61 (76%) of the patients, were multiple in 52 (85%) of the cases, and clinically evident in 32 (52%). Only multiple fractures were more frequent in patients with ectopic ACTH hypersecretion (P &lt; 0.05). Lumbar spine BMD was the best predictor of vertebral fractures (P &lt; 0.01). Surprisingly, amenorrheic and eumenorrheic women had similar BMD values and fracture prevalence. CONCLUSION: A high prevalence (76%) of vertebral fracture was revealed, regardless of the etiology of the patients' hypercortisolism. The harmful effects of F excess at the spine were partly counterbalanced by the increased androgen production but were not affected by gonadal status in women

Advances in functional imaging of differentiated thyroid cancer

Abstract: The present review provides a description of recent advances in the field of functional imaging that takes advantage of the functional characteristics of thyroid neoplastic cells (such as radioiodine uptake and FDG uptake) and theragnostic approach of differentiated thyroid cancer (DTC). Physical and biological characteristics of available radiopharmaceuticals and their use with state-of-the-art technologies for diagnosis, treatment, and follow-up of DTC patients are depicted. Radioactive iodine is used mostly with a therapeutic intent, while PET/CT with 18F-FDG emerges as a useful tool in the diagnostic management and complements the use of radioactive iodine. Beyond 18F-FDG PET/CT, other tracers including 124I, 18F-TFB and 68Ga-PSMA, and new methods such as PET/MR, might offer new opportunities in selecting patients with DTC for specific imaging modalities or treatments