Annals of nuclear cardiology最新文献

Takayasu arteritis (TAK) is classified as large-vessel vasculitis caused by inflammation. It is often difficult to identify on clinical examination, and ¹⁸F-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET) plays an indispensable role in diagnosing TAK by detecting the location and grade of the inflammatory lesions. The clinical utility of ¹⁸F-FDG PET has been established by clinical evidence, and ¹⁸F-FDG PET was added to the Japanese national health insurance listing in April 2018. In TAK, ¹⁸F-FDG uptake shows typical findings and is easily distinguished, except from physiological uptake. Particularly, the clinical significance of ¹⁸F-FDG PET is that can present not only with stenosis but also without stenosis in the arteries, which means that therapeutic intervention is possible before irreversible stenosis develops in the arteries. Additionally, ¹⁸F-FDG PET has superior diagnostic accuracy because it allows quantitative analysis using the maximum standardized uptake value. The analysis is used for the assessment of disease activity of TAK and can be utilized for therapeutic intervention in case of repeating remission during the follow-up term.

Sarcoidosis is a significant disease affecting the heart. ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) is a well-validated method for identifying significant focal inflammatory sarcoid lesions. The recent progress in image interpretation in nuclear medicine improves the diagnosis and the risk stratification in patients with cardiac sarcoidosis. Especially, metabolic activity, texture analysis, phase analysis, right ventricle assessment, and digital PET/CT are promising methods to assess cardiac sarcoidosis. This review focuses on the latest data analyses and image interpretation used in nuclear medicine to assess cardiac sarcoidosis.

Heart failure is associated with a significant change in the energy metabolism of the heart. We aimed to elucidate the altered energetics during the progression of heart failure. We used radioactive metabolic tracers to assess the substrate uptake. In a rat model of heart failure, the glucose uptake increased significantly at the stage of left ventricular hypertrophy, whereas the uptake of fatty acids decreased at the stage of heart failure, with decreased energy reserve during the transition of cardiac hypertrophy to failure. Metabolic modulator which enhances glucose oxidation ameliorated the decrease in cardiac function. We also validated the close correlation with mitochondrial membrane potentials and ^99mtechnetium sestamibi (^99mTc-MIBI) in vivo and at the organ level. The retention of ^99mTc-MIBI signals was correlated with the severity of heart failure. Nuclear medicine is a powerful tool to understand the mechanism of cardiac remodeling in heart failure.

Noninvasive quantification of myocardial blood flow with PET is a vital tool for detecting and monitoring of coronary artery disease. However, current standard cylindrical PET scanners are not optimized for cardiac imaging because they are designed mainly for whole-body imaging. In this study, we proposed two compact geometries, the elliptical geometry and the D-shape geometry, for cardiac-dedicated PET systems. We then evaluated their performance compared with a whole-body-size cylindrical geometry by using the Geant4 Monte Carlo simulation toolkit. In the simulation, an elliptical water phantom was scanned for 10-sec, and we calculated the sensitivity and the noise-equivalent count rate (NECR). Subsequently, a digital chest phantom was scanned for 30-sec and the coincidence data were reconstructed by in-house image reconstruction software. We evaluated the image noise in the liver region and the contrast recoveries in the heart region. Even with the limited number of detectors, the proposed compact geometries showed higher sensitivity than the whole-body geometry. The D-shape geometry achieved 47% higher NECR and 44% lower image noise compared with the whole-body cylindrical geometry. However, the contrasts in the hot area obtained by the proposed compact geometries were not as good as that obtained by the whole-body cylindrical geometry. There was no considerable difference in image quality between the elliptical geometry and the D-shape geometry. In conclusion, the compact geometries we have proposed are promising designs for a high-sensitivity and low-cost cardiac-dedicated PET system. A further study using a defect phantom model is required to evaluate the contrast of cold areas.

Background: Sample size estimation is an important and integral part of a research protocol. While "how large a sample?" is a simple question, the answer is only meaningful within the context of the research question. Methods: Clear definitions of the variable of interest and target population parameters are key to estimating sample size. In turn the sample must be sized such that it can accurately detect the 'effect' of interest, adequately represent the target population and maintain maximum design efficiency. Four basic pieces of information are utilized in most sample estimation across all clinical research: significance level, power, magnitude of effect and variability of the variable of interest. Results/Discussion: Preliminary determination of these will greatly facilitate work with a biostatistician or a computer application to create a sample size estimation. While applications can support relatively simple sample size calculations consultation with a biostatistician is recommended.

Objective: The bone scan plays an important role for detecting number of conditions relating to bones, including: bone cancer or bone metastasis, bone inflammation. Extraosseous uptake, in particular, myocardial uptake, was observed in some patients examined with the bone scans. Positive uptake of ^99mTc-labeled bone radiotracers is associated with cardiac amyloidosis. However, the frequency and cause of positive cardiac ^99mTc-MDP uptake have not been fully studied. In this regard, the aim of this study was to assess the frequency and characteristics of patients with high myocardi-al uptake of bone scintigraphy in daily clinical practice setting. Methods: We retrospectively analyzed 4180 bone scintigraphies performed in daily clinical practice during 7-years period. The intensity of the myocardial uptake was graded based on a visual scale ranging from 0 to 3 points. Score 0 indicates the absence of uptake. Score 1 defined uptake less than that of bone (referred to as the adjacent rib). Uptake similar to that of bone was classified score 2. Score 3 was defined as uptake greater than that of reference bone. Positive myocardial uptake included a visual score 2 or 3. Result: Positive ^99mTc-MDP myocardial uptake occurred in 12 patients among 4180 patients (0.3%). 7 of 12 positive scan patients were consistent with amyloidosis confirmed by biopsy. In these patients, the mean age was 75.6 ± 5.2 years old. Ten cases showed biventricular uptake and 2 showed LV uptake only. Conclusion: Positive cardiac uptake of bone scintigraphic agents was present in 0.3% of bone scintigraphies in a clinical practice setting. This may be a sign of cardiac amyloidosis involvement which may give the presence of extraosseous bone tracer uptake its own importance and a new role.

Introduction: The Japanese Circulation Society (JCS) recently published new guidelines for the diagnosis and treatment of Cardiac Sarcoidosis (CS). There are two other guideline documents, the World Association of Sarcoidosis and Other Granulomatous Disorders Sarcoidosis Organ (WASOG) Assessment Instrument created in 1999 and updated in 2014. Also, in 2014, the Heart Rhythm Society (HRS) published their international guideline document. As co-chair of the HRS document I have been invited to compare and contrast the management aspects of the HRS guidelines with the new JCS document. Comments: (i) The HRS document recommended a stepwise approach to VT management and the JCS document is somewhat similar; but with some key differences. (ii) The HRS statement suggested that an ICD for CS patients with an indication for a pacemaker "can be useful". The JCS document take a similar position although with some additional criteria related to National Health Institute Coverage guidelines. (iii) Both HRS and the JCS documents agree that ICDs are recommended in patients with general guideline indications for primary prevention (i.e. LVEF less than 35%). However which additional patients should be considered for ICDs is controversial. The 2016 JCS document is broadly similar, with the major exception that it is recommended that all patients with LVEF 35-50% should have an EP study. Conclusion: The Japanese have been leaders in many aspects of CS including in guideline development. It is clear that the future of CS management is bright, with increasing international collaborations and also multiple efforts underway to obtain higher quality data to inform future guidelines.

The COVID-19 pandemic has altered all aspects of performing medical procedures throughout the world. It is important to stratify patients into categories according to the likelihood that a requested exam will result in a change in acute management. Health care staff should maintain adequate distancing and engage in frequent hand washing, and personnel who are patient-facing should put on PPE at all times. All patient-touching apparatus should be disinfected between patients according to the Infection Control protocols of the institutions. Most labs have chosen to have patients wear surgical masks to afford some level of protection for them. Efforts should be implemented to enable remote reading and remote reporting of study results. The guidelines presented in this paper are based on the currently available information regarding SARS-CoV-2 (COVID-19) viral infections, but it is essential that all laboratories comply with evolving recommendations of their institutions and public health authorities.

Background: Obesity increases the risk for development of heart failure (HF) but, when present is likely to be related to better outcomes in patients with HF. This study aimed to clarify the paradoxical prognostic values of visceral obesity in association with cardiac sympathetic function in HF patients. Methods and Results: A total of 653 consecutive patients with systolic HF who underwent visceral adiposity area (VAA) measurements using a computed tomographic technique were divided into 3 groups: VAA 1, area <80 cm²; VAA 2, area 80-140 cm²; VAA 3, area >140 cm². Sympathetic innervation was quantified by ¹²³I-MIBG cardiac activity. Patients were followed up for an average of 22 months with a primary endpoint of lethal cardiac events (CE). The CE group (n=200) had a lower late heart-to mediastinum ratio (HMR) and a smaller VAA than those in the non-CE group. Rates of overall CE/HF death were inversely correlated with VAA: 39.2% ± 6.2% for VAA 1, 27.4% ± 19.9% for VAA 2 and 24.1% ± 15.3% for VAA 3. In addition to sudden cardiac death rate, lethal arrhythmic event rate increased in association with visceral fat obesity: 3.0% for VAA 1, 7.5% for VAA 2 and 8.8% for VAA 3. Late HMR identified high-risk sub-populations in each group. Conclusion: Visceral obesity has paradoxical prognostic implications in terms of HF mortality and lethal arrhythmic/sudden cardiac death events. Cardiac sympathetic denervation and quantitative visceral adiposity are synergistically associated with overall cardiac mortality, contributing to better risk stratification of HF patients.