Challenging the neuronal MIBG uptake by pharmacological intervention: effect of a single dose of oral amitriptyline on regional cardiac MIBG uptake

Imaging of Pheochromocytomas and Paragangliomas

Pheochromocytomas/paragangliomas are unique in their highly variable molecular landscape driven by genetic alterations, either germline or somatic. These mutations translate into different clusters with distinct tumor locations, biochemical/metabolomic features, tumor cell characteristics (eg, receptors, transporters), and disease course. Such tumor heterogeneity calls for different imaging strategies in order to provide proper diagnosis and follow-up. This also warrants selection of the most appropriate and locally available imaging modalities tailored to an individual patient based on consideration of many relevant factors including age, (anticipated) tumor location(s), size, and multifocality, underlying genotype, biochemical phenotype, chance of metastases, as well as the patient's personal preference and treatment goals. Anatomical imaging using computed tomography and magnetic resonance imaging and functional imaging using positron emission tomography and single photon emission computed tomography are currently a cornerstone in the evaluation of patients with pheochromocytomas/paragangliomas. In modern nuclear medicine practice, a multitude of radionuclides with relevance to diagnostic work-up and treatment planning (theranostics) is available, including radiolabeled metaiodobenzylguanidine, fluorodeoxyglucose, fluorodihydroxyphenylalanine, and somatostatin analogues. This review amalgamates up-to-date imaging guidelines, expert opinions, and recent discoveries. Based on the rich toolbox for anatomical and functional imaging that is currently available, we aim to define a customized approach in patients with (suspected) pheochromocytomas/paragangliomas from a practical clinical perspective. We provide imaging algorithms for different starting points for initial diagnostic work-up and course of the disease, including adrenal incidentaloma, established biochemical diagnosis, postsurgical follow-up, tumor screening in pathogenic variant carriers, staging and restaging of metastatic disease, theranostics, and response monitoring.

European Association of Nuclear Medicine Practice Guideline/Society of Nuclear Medicine and Molecular Imaging Procedure Standard 2019 for radionuclide imaging of phaeochromocytoma and paraganglioma

PURPOSE

Diverse radionuclide imaging techniques are available for the diagnosis, staging, and follow-up of phaeochromocytoma and paraganglioma (PPGL). Beyond their ability to detect and localise the disease, these imaging approaches variably characterise these tumours at the cellular and molecular levels and can guide therapy. Here we present updated guidelines jointly approved by the EANM and SNMMI for assisting nuclear medicine practitioners in not only the selection and performance of currently available single-photon emission computed tomography and positron emission tomography procedures, but also the interpretation and reporting of the results.

METHODS

Guidelines from related fields and relevant literature have been considered in consultation with leading experts involved in the management of PPGL. The provided information should be applied according to local laws and regulations as well as the availability of various radiopharmaceuticals.

CONCLUSION

Since the European Association of Nuclear Medicine 2012 guidelines, the excellent results obtained with gallium-68 (68Ga)-labelled somatostatin analogues (SSAs) in recent years have simplified the imaging approach for PPGL patients that can also be used for selecting patients for peptide receptor radionuclide therapy as a potential alternative or complement to the traditional theranostic approach with iodine-123 (123I)/iodine-131 (131I)-labelled meta-iodobenzylguanidine. Genomic characterisation of subgroups with differing risk of lesion development and subsequent metastatic spread is refining the use of molecular imaging in the personalised approach to hereditary PPGL patients for detection, staging, and follow-up surveillance.

Radionuclide imaging of cardiac sympathetic innervation in heart failure: unlocking untapped potential

Heart failure (HF) is associated with sympathetic overactivity, which contributes to disease progression and arrhythmia development. Cardiac sympathetic innervation imaging can be performed using radiotracers that are taken up in the presynaptic nerve terminal of sympathetic nerves. The commonly used radiotracers are (123)I-metaiodobenzylguanidine ((123)I-mIBG) for planar and single-photon emission computed tomography imaging, and (11)C-hydroxyephedrine for positron emission tomography imaging. Sympathetic innervation imaging has been used in assessing prognosis, response to treatment, risk of ventricular arrhythmias and sudden death and prediction of response to cardiac resynchronization therapy in patients with HF. Other potential applications of these techniques are in patients with chemotherapy-induced cardiomyopathy, predicting myocardial recovery in patients with left ventricular assist devices, and assessing reinnervation following cardiac transplantation. There is a lack of standardization with respect to technique of (123)I-mIBG imaging that needs to be overcome for the imaging modality to gain popularity in clinical practice.

Impact of medications on mIBG uptake, with specific attention to the heart: Comprehensive review of the literature

BACKGROUND

A critical review of the literature on drug interactions with mIBG uptake was performed to allow formulation of contemporary guidance regarding withholding medications prior to clinical imaging studies.

METHODS

Published information was extracted on the experimental system used, the quantitative characteristics of the measurements, and whether any data directly examining cardiac tissues were included. Level of evidence for each medication category was assessed on a qualitative scale of very low, low, medium, or high. Strength of medication effect for inhibition of mIBG uptake was judged as none, weak, moderate, or strong.

RESULTS

The only medications for which level of evidence was judged high were labetalol and reserpine. Level of evidence was judged medium for tricyclic antidepressants, calcium channel blockers, and antiarrhythmics (specifically amiodarone). Evidence was judged sufficient to recommend withholding labetalol and the tricyclic antidepressants prior to mIBG cardiac imaging. Mechanistic evidence was sufficient to suggest consideration of withdrawal of sympathomimetic amines and serotonin-norepinephrine reuptake inhibitors (SNRIs).

CONCLUSIONS

As there is strong evidence for inhibition of mIBG uptake in only a small number of compounds, clinical decisions regarding withdrawal of concomitant medications should be individualized by considering the potential consequences of a false-positive (artificially low cardiac uptake) imaging result.

Milnacipran influences the indexes of I-metaiodobenzylguanidine scintigraphy in elderly depressed patients

AIM

This study investigated whether or not and how much milnacipran influences the indexes of I-metaiodobenzylguanidine (I-MIBG) scintigraphy, early heart-to-mediastinum (H/M) ratio, delayed H/M ratio, and wash-out rate.

METHODS

Six elderly depressed patients participated in the study. All six patients met the diagnostic criteria for a major depressive disorder. They were taking milnacipran for their depression. They needed differential diagnosis for Lewy body diseases due to their symptomatology. I-MIBG scintigraphy was performed twice for each subject, once under prescription of milnacipran and the other without prescription of milnacipran.

RESULTS

Both early and delayed phase H/M ratio were significantly lower when taking milnacipran (early phase H/M ratio, P < 0.01, Cohen's d 1.62; delayed phase H/M ratio, P < 0.005, Cohen's d 1.98) than when not taking the drug. Wash-out rate (%) was significantly higher when taking milnacipran (P < 0.05, Cohen's d 2.31) than when off the drug.

CONCLUSION

Taking milnacipran substantially influences the indexes of I-MIBG scintigraphy, indicating that taking the drug possibly causes a false-positive result for Lewy body diseases diagnosis.

Levodopa challenge test and (123) I-metaiodobenzylguanidine scintigraphy for diagnosing Parkinson's disease

OBJECTIVES

To explore the possibility of a generally applicable tool for the immediate diagnosis of Parkinson's disease (PD) in its early stage, we compared the sensitivity and specificity of an acute levodopa challenge test with that of (123) I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy.

MATERIALS AND METHODS

A consecutive series of 45 patients with extrapyramidal symptoms were recruited to the acute levodopa challenge and evaluated for improvement by use of the Unified Parkinson's Disease Rating Scale motor scores. Of these patients, 32 of them were also examined by MIBG scintigraphy. The patients were followed up for at least 24 months, and 22 patients were diagnosed as having clinically definite PD.

RESULTS

The sensitivity and specificity of the acute levodopa challenge test to predict clinical diagnosis of PD were 81.8% and 81.8%, respectively, which were better than those obtained by MIBG scintigraphy (62.5% and 62.5%). In both early- and middle-stages of PD, the test gave better sensitivity than MIBG scintigraphy.

CONCLUSIONS

Considering that the well-established and frequently referred clinical diagnostic criteria require longitudinal observation for at least 24 months, the acute levodopa challenge test can be used as an immediate diagnostic tool for PD with sensitivity and specificity comparable to those of MIBG.

EANM 2012 guidelines for radionuclide imaging of phaeochromocytoma and paraganglioma

PURPOSE

Radionuclide imaging of phaeochromocytomas (PCCs) and paragangliomas (PGLs) involves various functional imaging techniques and approaches for accurate diagnosis, staging and tumour characterization. The purpose of the present guidelines is to assist nuclear medicine practitioners in performing, interpreting and reporting the results of the currently available SPECT and PET imaging approaches. These guidelines are intended to present information specifically adapted to European practice.

METHODS

Guidelines from related fields, issued by the European Association of Nuclear Medicine and the Society of Nuclear Medicine, were taken into consideration and are partially integrated within this text. The same was applied to the relevant literature, and the final result was discussed with leading experts involved in the management of patients with PCC/PGL. The information provided should be viewed in the context of local conditions, laws and regulations.

CONCLUSION

Although several radionuclide imaging modalities are considered herein, considerable focus is given to PET imaging which offers high sensitivity targeted molecular imaging approaches.

Detection of Lewy body disease in patients with late-onset depression, anxiety and psychotic disorder with myocardial meta-iodobenzylguanidine scintigraphy

PURPOSE

Lewy body disease (LBD) is comprised of a spectrum of diseases that includes Parkinson's disease (PD), PD dementia (PDD) and dementia with LBD (DLBD), an array of dementia, and motor symptoms. Low uptake of myocardial meta-iodobenzylguanidine (MIBG) validates diagnosis of LBD. Psychiatric symptoms sometimes precede atypical Parkinsonian syndromes in LBD. Of 34 patients with low MIBG uptake, late-onset depressive, anxiety, or psychotic symptoms were analyzed in term of clinical profiles.

METHOD

Thirty-four patients were classed into three groups according to three main symptoms, 11 patients with visual hallucination (VH), 13 with depression-anxiety (DA), and 10 with psychosis with cognitive disturbance (PCD). Cutoff values of heart-to-mediastinum (HM) ratio of MIBG were set at 1.78 in early phase or 1.68 in late phase.

RESULTS

Group VH patients showed a trend toward higher age at onset and occipital lobe hypoperfusion. Group DA patients lacked central and core features of DLBD and five of them showed frontal lobe hypoperfusion. Group PCD patients had the highest frequencies of suggestive symptoms and UPDRS scores and showed temporal lobe hypoperfusion. HM ratio was not associated with clinical profiles of three groups. Cognitive function was more severely disturbed in atypical Parkinsonian syndrome cases at an initial visit.

CONCLUSION

Group VH was considered to DLBD, and Group PCD was regarded as PDD or DLBD with early psychotic presentation. Group DA has a possibility of early depression or anxiety disorder of LBD although it lacked DLBD criteria. Atypical Parkinsonian syndromes are associated with cognitive disturbance irrespective of psychiatric profiles.

Declared use of medication in sports

OBJECTIVE

To assess and compare the prevalence of declared medication, such as corticosteroids, nonsteroidal anti-inflammatory drugs (NSAIDs), beta2-agonists, narcotic analgesics, anaesthetics, and antidepressant drugs, in time and between different sports among athletes tested for doping control in a 4-year period.

DESIGN

Survey study.

SETTING

Belgium.

PARTICIPANTS

This paper reviews the data obtained from 18,645 doping control forms gathered between 2002 and 2005 from national doping organisations in Belgium and The Netherlands, the International Cycling Union (UCI), and the Belgian Cycling Federation.

INTERVENTION

All athletes were asked by doping control officers to declare the medication taken in the last 3 days before competition after which the doping control forms were double blinded and handed over to the laboratory.

MAIN OUTCOME MEASUREMENTS

Classification of declared medication according to the active ingredient.

RESULTS

The overall declared use of medication belonging to one of the monitored categories increased from 19.8% in 2002 to 24.67% in 2005. Differences in use of medication were observed between sports with a higher prevalence of use of NSAIDs in ball sports compared to other sports and a higher use of beta-agonists and corticosteroids in cycling with percentages of declared corticosteroid use in samples from the UCI exceeding 36% in 2005.

CONCLUSION

These results indicate that the current granting of therapeutic use exemption for corticosteroids and beta-agonists needs to be revised and that threshold levels for beta-agonists should be implemented.

Highlights of the Annual Congress of the European Association of Nuclear Medicine, Helsinki 2004, and a dash of horizon scanning

The Annual Congress of the European Association of Nuclear Medicine represents the major scientific and professional event in the field of nuclear medicine in Europe. Specialists from all allied professions meet to discuss the latest findings and discoveries. A very large industrial exhibition demonstrates the latest technological innovations and developments. This Highlights Lecture summarises the scientific and medical advances discussed at this important gathering. The lecture covers a significant proportion of the data presented and/or discussed in up-to-date reviews, and places some of the trends encountered in the context of the evolution of the field as a whole. There is much food for thought in most areas of nuclear medicine: advances in instrumentation and data processing, progress in radiochemistry and pharmacy, novel diagnostics and therapeutics, and new insights in known areas of clinical application such as neurology and psychiatry, cardiology, oncology, endocrine disorders, paediatrics, nephro-urology and musculoskeletal disorders. This Highlights Lecture is, however, only a brief resume of the vast amount of data discussed, which can be found in much greater detail in the Congress Proceedings, published as volume 31, supplement 2 of Eur J Nucl Med Mol Imaging in August 2004.

Cardiac neurotransmission SPECT imaging

The sympathetic nervous system has great influence on cardiovascular physiology. Cardiac neurotransmission single photon emission computed tomography (SPECT) imaging allows in vivo noninvasive assessment of presynaptic reuptake and storage of neurotransmitters, which offers characterization of the cardiac neuronal function in different diseases of the heart and other altered metabolic or functional conditions. Therefore assessment of the integrity of cardiac sympathetic innervation may help in the diagnosis of these disorders, as well as in prognostication, and will result in better therapy and outcome. At present, the most widely available SPECT tracer by which to assess cardiac neurotransmission is metaiodobenzylguanidine labeled with iodine 123. This article focuses on reviewing the characteristics of cardiac SPECT imaging with I-123 metaiodobenzylguanidine and its role in the assessment of pathophysiologic changes during relevant clinical conditions.