Advances in Radiopharmaceutical Sciences for Vascular Inflammation Imaging: Focus on Clinical Applications.

Biomedical imaging technologies offer identification of several anatomic and molecular features of disease pathogenesis. Molecular imaging techniques to assess cellular processes in vivo have been useful in advancing our understanding of several vascular inflammatory diseases. For the non-invasive molecular imaging of vascular inflammation, nuclear medicine constitutes one of the best imaging modalities, thanks to its high sensitivity for the detection of probes in tissues. 2-[18F]fluoro-2-deoxy-d-glucose ([18F]FDG) is currently the most widely used radiopharmaceutical for molecular imaging of vascular inflammatory diseases such as atherosclerosis and large-vessel vasculitis. The combination of [18F]FDG and positron emission tomography (PET) imaging has become a powerful tool to identify and monitor non-invasively inflammatory activities over time but suffers from several limitations including a lack of specificity and avid background in different localizations. The use of novel radiotracers may help to better understand the underlying pathophysiological processes and overcome some limitations of [18F]FDG PET for the imaging of vascular inflammation. This review examines how [18F]FDG PET has given us deeper insight into the role of inflammation in different vascular pathologies progression and discusses perspectives for alternative radiopharmaceuticals that could provide a more specific and simple identification of pathologies where vascular inflammation is implicated. Use of these novel PET tracers could lead to a better understanding of underlying disease mechanisms and help inform the identification and stratification of patients for newly emerging immune-modulatory therapies. Future research is needed to realize the true clinical translational value of PET imaging in vascular inflammatory diseases.

Scope of Practice of US Interventional Cardiologists from an Analysis of Medicare Billing Data.

The contemporary scope of practice of interventional cardiologists (ICs) in the United States and recent trends are unknown. Using Medicare claims from 2013 to 2017, we categorized ICs into 4 practice categories (only percutaneous coronary intervention [PCI], PCI with noninvasive imaging, PCI with specialized interventions [peripheral/structural], and all 3 services) and evaluated associations with region, hospital bed size and teaching status, gender, and graduation year. Of 6,083 ICs in 2017, 10.9% performed only PCI, 68.3% PCI with noninvasive imaging, 5.7% PCI with specialized interventions, and 15.1% all 3 services. A higher proportion of Northeast ICs (vs South ICs) were performing only PCI (24.8% vs 7.3%) and PCI with specialized interventions (12% vs 3.4%), but lower PCI and noninvasive imaging (53.8% vs 71.7%) and all 3 services (9.3% and 17.6%). Regarding ICs at larger hospitals (bed size >575 vs <218), a higher proportion was performing only PCI (23.8% vs 5.2%) or PCI with specialized interventions (13.5% vs 1.7%) and lower proportion was performing PCI with noninvasive imaging (48.8% vs 78%), similar to teaching hospitals. Female ICs (vs male ICs) more frequently performed only PCI (18.9% vs 10.6%) and less frequently all 3 services (8.3% vs 15.4%). A lower proportion of recent graduates (2001 to 2016) performed only PCI (9.8% vs 13.8%) and PCI with noninvasive imaging (66.3% vs 72.6%) but a higher proportion performed all 3 services (18% vs 8.4%) than earlier graduates (1959 to 1984). From 2013 to 2017, only PCI and PCI with noninvasive imaging decreased, whereas PCI and specialized interventions and all 3 services increased (all p <0.001). In conclusion, there is marked heterogeneity in practice responsibilities among ICs, which has implications for training and competency assessments.

Responsible Radionuclide Cancer Care.

The landscape of nuclear oncology is rapidly changing. The advent of molecular radionuclide theranostics, multidisciplinary tumor board decision making, artificial intelligence and radiomics interpretation of diagnostic imaging, evolution of pharmacogenomics prediction of tumor response, and regulatory requirements for prospective individual dosimetry are just some of the elements which are broadening the essence of physician responsibility. The burgeoning knowledge base essential for mastering the emergent technologies, and their profound effect on moral philosophic aspects of provision of cancer care, are challenging. The new relationship of the theranostic nuclear physician with respect to shared care of the individual patient, particularly with regard to transparency, accountability, and responsibility for targeted radionuclide diagnosis and therapy of cancer, will be explored in this update.

Nanobodies for Medical Imaging: About Ready for Prime Time?

Recent advances in medical treatments have been revolutionary in shaping the management and treatment landscape of patients, notably cancer patients. Over the last decade, patients with diverse forms of locally advanced or metastatic cancer, such as melanoma, lung cancers, and many blood-borne malignancies, have seen their life expectancies increasing significantly. Notwithstanding these encouraging results, the present-day struggle with these treatments concerns patients who remain largely unresponsive, as well as those who experience severely toxic side effects. Gaining deeper insight into the cellular and molecular mechanisms underlying these variable responses will bring us closer to developing more effective therapeutics. To assess these mechanisms, non-invasive imaging techniques provide valuable whole-body information with precise targeting. An example of such is immuno-PET (Positron Emission Tomography), which employs radiolabeled antibodies to detect specific molecules of interest. Nanobodies, as the smallest derived antibody fragments, boast ideal characteristics for this purpose and have thus been used extensively in preclinical models and, more recently, in clinical early-stage studies as well. Their merit stems from their high affinity and specificity towards a target, among other factors. Furthermore, their small size (~14 kDa) allows them to easily disperse through the bloodstream and reach tissues in a reliable and uniform manner. In this review, we will discuss the powerful imaging potential of nanobodies, primarily through the lens of imaging malignant tumors but also touching upon their capability to image a broader variety of nonmalignant diseases.

Radionuclide Imaging for Neuroscience: Current Opinion and Future Directions.

This meeting report summarizes a Consultants Meeting that was held at International Atomic Energy Agency headquarters in Vienna to provide an update on radionuclide imaging for neuroscience applications.

Enhancing Scintigraphy for Evaluation of Gastric, Small Bowel, and Colonic Motility.

This article reviews the latest enhancements in standards and technology for performing gastric emptying and associated small bowel and colon transit scintigraphic studies. It discusses how developments in appropriate use criteria, American Medical Association Current Procedural Terminology coding, and advanced commercial software permit clinicians to obtain more comprehensive physiologic studies of gastric, small bowel, and colon gastrointestinal motility disorders. It shows how gastrointestinal scintigraphy has expanded to permit assessments of global and regional (fundic and antral) gastric motility and how it permits a single study (whole-gut transit scintigraphy), including measurement of solid and liquid gastric emptying and small bowel and colon transit.

The Future of Imaging in Axial Spondyloarthritis.

This article discusses the current position of conventional radiography and MRI, the techniques recommended by the European League Against Rheumatism for use in imaging in axial spondyloarthritis (axSpA). Several challenges and areas of development regarding radiography and MRI in axSpA are considered. Also, a few interesting focus points for future research are noted. Besides the recommended techniques, this article discusses several nuclear imaging techniques and the usability of these techniques in daily practice.

Trends in Use of Medical Imaging in US Health Care Systems and in Ontario, Canada, 2000-2016.

Importance: Medical imaging increased rapidly from 2000 to 2006, but trends in recent years have not been analyzed. Objective: To evaluate recent trends in medical imaging. Design, Setting, and Participants: Retrospective cohort study of patterns of medical imaging between 2000 and 2016 among 16 million to 21 million patients enrolled annually in 7 US integrated and mixed-model insurance health care systems and for individuals receiving care in Ontario, Canada. Exposures: Calendar year and country (United States vs Canada). Main Outcomes and Measures: Use of computed tomography (CT), magnetic resonance imaging (MRI), ultrasound, and nuclear medicine imaging. Annual and relative imaging rates by imaging modality, country, and age (children [<18 years], adults [18-64 years], and older adults [≥65 years]). Results: Overall, 135 774 532 imaging examinations were included; 5 439 874 (4%) in children, 89 635 312 (66%) in adults, and 40 699 346 (30%) in older adults. Among adults and older adults, imaging rates were significantly higher in 2016 vs 2000 for all imaging modalities other than nuclear medicine. For example, among older adults, CT imaging rates were 428 per 1000 person-years in 2016 vs 204 per 1000 in 2000 in US health care systems and 409 per 1000 vs 161 per 1000 in Ontario; for MRI, 139 per 1000 vs 62 per 1000 in the United States and 89 per 1000 vs 13 per 1000 in Ontario; and for ultrasound, 495 per 1000 vs 324 per 1000 in the United States and 580 per 1000 vs 332 per 1000 in Ontario. Annual growth in imaging rates among US adults and older adults slowed over time for CT (from an 11.6% annual percentage increase among adults and 9.5% among older adults in 2000-2006 to 3.7% among adults in 2013-2016 and 5.2% among older adults in 2014-2016) and for MRI (from 11.4% in 2000-2004 in adults and 11.3% in 2000-2005 in older adults to 1.3% in 2007-2016 in adults and 2.2% in 2005-2016 in older adults). Patterns in Ontario were similar. Among children, annual growth for CT stabilized or declined (United States: from 10.1% in 2000-2005 to 0.8% in 2013-2016; Ontario: from 3.3% in 2000-2006 to -5.3% in 2006-2016), but patterns for MRI were similar to adults. Changes in annual growth in ultrasound were smaller among adults and children in the United States and Ontario compared with CT and MRI. Nuclear medicine imaging declined in adults and children after 2006. Conclusions and Relevance: From 2000 to 2016 in 7 US integrated and mixed-model health care systems and in Ontario, rates of CT and MRI use continued to increase among adults, but at a slower pace in more recent years. In children, imaging rates continued to increase except for CT, which stabilized or declined in more recent periods. Whether the observed imaging utilization was appropriate or was associated with improved patient outcomes is unknown.

Diagnostic performance of imaging investigations in detecting and differentiating cardiac amyloidosis: a systematic review and meta-analysis.

AIMS: The study aims to systematically assess the diagnostic performance of cardiac magnetic resonance (CMR) and nuclear scintigraphy (index tests) for the diagnosis and differentiation of subtypes of cardiac amyloidosis. METHODS AND RESULTS: MEDLINE and Embase electronic databases were searched for studies evaluating the diagnostic performance of CMR or nuclear scintigraphy in detecting cardiac amyloidosis and subsequently in differentiating transthyretin amyloidosis (ATTR) from immunoglobulin light-chain (AL) amyloidosis. In this meta-analysis, histopathological examination of tissue from endomyocardial biopsy (EMB) or extra-cardiac organs were reference standards. Pooled sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio were calculated, and a random effects meta-analysis was used to estimate diagnostic odds ratios. Methodological quality was assessed using a validated instrument. Of the 2947 studies identified, 27 met the criteria for inclusion. Sensitivity and specificity of CMR in diagnosing cardiac amyloidosis was 85.7% and 92.0% against EMB reference and 78.9% and 93.9% with any organ histology reference. Corresponding sensitivity and specificity of nuclear scintigraphy was 88.4% and 87.2% against EMB reference and 82.0% and 98.8% with histology from any organ. CMR was unable to reliably differentiate ATTR from AL amyloidosis (sensitivity 28.1-99.0% and specificity 11.0-60.0%). Sensitivity and specificity of nuclear scintigraphy in the differentiation of ATTR from AL amyloidosis ranged from 90.9% to 91.5% and from 88.6% to 97.1%. Pooled negative likelihood ratio and positive likelihood ratio for scintigraphy in this setting were 0.1 and 8, with EMB reference standard. Study quality assessed by QUADAS-2 was generally poor with evidence of bias. CONCLUSIONS: Cardiac magnetic resonance is a useful test for diagnosing cardiac amyloidosis but is not reliable in further classifying the disease. Nuclear scintigraphy offers strong diagnostic performance in both the detection of cardiac amyloidosis and differentiating ATTR from AL amyloidosis. Our findings support the use of both imaging modalities in a non-invasive diagnostic algorithm that also tests for the presence of monoclonal protein.

Impact of International Atomic Energy Agency support to the development of nuclear cardiology in low-and-middle-income countries: Case of Latin America and the Caribbean.

Cardiovascular diseases (CVDs) are the leading cause of death in Latin America and the Caribbean (LAC) region as well as worldwide. Lifestyle, nutritional habits and the upsurge of obesity have contributed to the increase in the prevalence of CVDs in the region. The role of nuclear cardiology in the management of patients with CVDs is well established. Particularly, myocardial perfusion imaging is widely used in LAC countries and has been increasingly integrated into the healthcare systems in the region for the diagnosis of coronary artery disease, risk stratification and to guide patient management. In its role to support countries around the world to address their health needs through the peaceful applications of nuclear techniques, the International Atomic Energy Agency (IAEA) has provided assistance to the LAC region for the establishment and strengthening of the nuclear cardiology practice. To that extent, the IAEA provides support in building capacities of multidisciplinary teams of professionals, the provision of medical equipment and the promotion of communication and exchange of knowledge among the different stakeholders. In addition, the IAEA encourages the participation of nuclear medicine centers in international multi-center research studies. In this paper, we present some of the projects through which the IAEA has supported the LAC region, including regional technical cooperation projects and coordinated research projects related to cardiology within the current multimodality approach to cardiac imaging.

Theranostics in neuroendocrine tumours: somatostatin receptor imaging and therapy.

Theranostics and its principles: pre-treatment selection of patients who are most likely to benefit from treatment by the use of a related, specific diagnostic test are integral to the treatment of patients with neuroendocrine tumours (NETs). This is due to NETs' important, but variable, somatostatin receptor (SSTR) expression, their heterogeneity and variation in site of primary and rate of progression. Only patients whose tumours have sufficient expression of SSTRs will benefit from SSTR-based radionuclide therapy and demonstrating this expression prior to therapy is essential. This article provides a relevant overview of NETs and the multiple facets of SSTR based theranostics, including imaging and therapy radionuclides; clinical efficacy and toxicity; patient selection and treatment and finally emerging radiopharmaceuticals and newer clinical applications.

Will 68Ga PSMA-radioligands be the only choice for nuclear medicine in prostate cancer in the near future? A clinical update. / ¿Constituirán en el futuro los radioligandos de 68Ga-PSMA la única elección de la Medicina Nuclear para el cáncer de próstata? Actualización clínica.

Prostate Cancer (PCa) represents the most common malignant tumor in men but according to the European Association of Urology (EAU) guidelines, a mass screening for PCa diagnosis should not be performed due to over-diagnosis and over-treatment related problems. An early clinical diagnosis is possible, mainly based on digital rectal examination and Prostatic Specific Agent (PSA) testing. However, the only mandatory test to define the presence of PCa is ultrasound guided-biopsy, obtained on multiple samples, which has also a high prognostic value. In this context, diagnostic imaging plays an important role as confirmed by EAU that in a 2016 update of their guidelines on PCa stated the importance of Positron Emission Tomography (PET) with 11C- or 18F-choline combined with computed tomography (CT) to identify local relapse, lymph node involvement and metastatic spread at all stages. Consequently, in 2017, the European Association of Nuclear Medicine (EANM) together with the Society of Nuclear Medicine and Molecular Imaging (SNMMI) published new guidelines for 68Ga-Prostate Specific Membrane Antigen (PSMA) PET/CT to help physicians in the recommendation, execution and interpretation of PET/CT scans in patients with PCa. Thus, the aim of this 'evidence paper' is to define the current diagnostic algorithm in PCa in order to increase the general level of confidence in approaching such a crucial topic.

Preoperative Cardiac Stress Testing in the Southern California Vascular Outcomes Improvement Collaborative.

BACKGROUND: The objective of this study was to examine the use of preoperative cardiac stress testing (PCST) in the Southern California Vascular Outcomes Improvement Collaborative (So Cal VOICe). METHODS: A retrospective review was performed on data in all modules of the So Cal VOICe from September 2012 through May 2016. PCST was defined as stress echocardiogram or nuclear stress test. A new postoperative myocardial infarction (MI) was defined as troponin elevation and/or electrocardiogram/imaging changes with or without ischemic symptoms. Only elective cases in patients with asymptomatic cardiac status were included in the study. RESULTS: During the study period, 3,063 procedures meeting the inclusion criteria were performed in 7 registries: carotid endarterectomy (CEA), carotid artery stent, thoracic endovascular aneurysm repair, infrainguinal bypass (Infra), endovascular aneurysm repair (EVAR), suprainguinal bypass (Supra), and open abdominal aortic aneurysm repair (OAAA). PCST varied across registries from 17% in PVI to 62% in OAAA. PCST in CEA varied across 9 institutions from 10% to 79%. PCST in EVAR varied across 7 institutions from 14% to 83%. PCST in Infra varied across 4 institutions from 10% to 57%. Of the 12 patients across all registries who had a new MI, 6 had PCST, one of which was abnormal. CONCLUSIONS: The incidence of PCST varies widely across registries and institutions in the So Cal VOICe. Despite the wide variation, the incidence of new postoperative MI is exceptionally low. Further studies should evaluate the cost-effectiveness of the PCST practices and future quality improvement efforts should focus on standardization of indications for PCST.

Differentiating between benign and malignant thyroid nodules: An evidence-based approach in general practice

BACKGROUND: The widespread use of imaging techniques has led to more frequent detection of thyroid nodules, and while the majority are benign, the risk of malignancy in an adult ranges from 7% to 15%. General practitioners (GPs) must be able to evaluate thyroid nodules and refer cases when appropriate. OBJECTIVES: The aim of this article is to bring GPs up to date on the evidence-based management of thyroid nodules, with specific focus on neoplastic nodules, while highlighting significant changes in the 2015 American Thyroid Association guidelines. DISCUSSION: Thyroid nodules frequently occur in the general population. Differentiating between a benign and malignant nodule can be challenging, and community guidelines have standardised investigation, management and follow-up procedures. The key tests for risk stratification of thyroid nodules include serum thyroid-stimulating hormone testing, ultrasonography and fine-needle aspiration. GPs should be aware of the latest evidence-based recommendations for the appropriate management of a thyroid nodule.

A quick glance at selected topics in this issue.

"A quick glance at selected topics in this issue" aims to highlight few randomly selected articles and provide a quick review to the readers.

Modern Imaging of Myocarditis: Possibilities and Challenges / Moderne Bildgebung bei Myokarditis: Möglichkeiten und Herausforderungen

UNLABELLED: Myocarditis is known as the chameleon of cardiac diseases. The symptoms and the course of disease vary greatly so that it is often challenging to establish a diagnosis. Early and accurate diagnosis is of utmost importance, since myocarditis is one of the leading causes of sudden cardiac death in young adults and represents an important precursor to dilated cardiomyopathy. Due to the constraints of the routinely used diagnostic approach, including clinical history and examination, laboratory testing, and electrocardiogram, different imaging modalities have emerged over the last decades as contributors to the noninvasive diagnosis of myocarditis. With this interdisciplinary review we would like to present the current state-of-the-art imaging of myocarditis across all available imaging modalities (i. e., echocardiography, cardiac magnetic resonance, cardiac computed tomography, and nuclear medicine). Furthermore, we present novel imaging techniques that might become useful in the near future for easier and more accurate diagnosis of this highly relevant disease. KEY POINTS: • Different imaging modalities are increasingly used in the diagnostic workup of myocarditis. • Several emerging imaging techniques are currently on the way to becoming part of the clinical routine. • This review summarizes the diagnostic value of echocardiography, CMR, CT, and nuclear medicine imaging. • There is special focus on the possibilities and challenges of novel imaging tools within the different modalities.