There are interesting differences between the practice of Nuclear Cardiology in Japan and that in the United States and associated unique challenges. Differences in patient body habitus and the perceived importance of limiting patient radiation dose have resulted in different radiopharmaceutical and imaging protocol preferences.Governmental approval and reimbursement policies for various radiopharmaceuticals have promulgated adoption of different clinical applications. Both countries have experienced a significant decline in the number of nuclear cardiology studies performed, in part due to decreased governmental funding and reimbursement and to the emergence of competing modalities. Whereas precertification and test substitution have impacted negatively on the sustainability and growth of nuclear cardiology in the United States, in Japan those deterrents have not yet been encountered. Instead, communication barriers between nuclear medicine physicians and referring cardiologists are cited as being of greater significance.

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Background: A number of previous studies have shown that myocardial viability can be assessed by positron emission tomography (PET) using ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG). However, there has been no multicenter study that verified the ability of this modality for diagnosing myocardial viability in Japan. We therefore conducted a prospective one arm’s unrandomized multicenter clinical trial in order to confirm the diagnostic ability of ¹⁸F-FDG for myocardial viability.
Methods: This study included patients with heart failure and impaired left ventricular function where conventional myocardial perfusion scintigraphy was not contributive for the diagnosis of myocardial viability,and assessed the diagnostic ability of ¹⁸F-FDG for myocardial viability in these patients. The diagnostic ability was determined on the basis of post-coronary vascularization improvement in myocardial wall motion in a myocardial segment with ¹⁸F-FDG uptake (i.e., positive predictive value). We also assessed the safety of ¹⁸F-FDG.
Results: Out of 49 patients who received ¹⁸F-FDG administration, 30 were included in the efficacy analysis set (mean age 64.4±14.6 years; 27 men and 3 women; mean follow-up period 228.6±74.5 days). The positive predictive value of ¹⁸F-FDG (95% two-sided confidence interval) in the 30 patients of the efficacy-analysis set was 63.9% (54.6-72.5%). Moreover, the proportion of patients with improved wall motion, on a per-patient basis, was 86.7% (26 of 30 cases). As for the safety, no serious adverse events occurred and the agent was well-tolerated.
Conclusions: The identification of myocardial viability by ¹⁸F-FDG will be widely beneficial in predicting improvement in myocardial wall motion after coronary revascularization. No serious safety concerns associated with the use of ¹⁸F-FDG were observed.

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Background: The clinical implementation of cardiac ¹²³Iodine-meta-iodobenzylguanidine (¹²³I-MIBG) scintigraphy for the evaluation of prognosis in patients with heart failure (HF) is still limited. This may partially be related to the long examination time with an almost 4 hour delay between the early and late acquisition. Additionally, outcome derived at different late acquisition times cannot be compared with each other. To assess whether earlier acquisition time of the late image is justified, the aim of present study was to evaluate in a HF patient cohort whether a developed direct comparison method for cardiac ¹²³I-MIBG imaging enables comparison of washout rates and late heart-to-mediastinum (H/M) ratios from 1 to 3 hours post injection (pi) with measurements at 4 hours pi.
Methods: Forty-eight patients with HF were clinically referred for cardiac ¹²³I-MIBG scintigraphy. The washout rate and late H/M ratio at 4 hours pi were estimated with a previous published linear model from heart and mediastinal counts at 1, 2 and 3 hour pi and compared with the actual values at 4 hour pi.
Results: The estimated washout rate and late H/M ratio at 4 hours pi from counts at 1 hour pi demonstrated large differences. However, the average estimated late H/M ratio at 4 hours pi derived from 2 and 3 hours pi did not differ with the actual late H/M ratio at 4 hours pi (P=0.84 and P=0.06). As well as, the actual washout rate at 4 hours pi and estimated washout rate at 4 hours pi derived from 3 hours pi did not differ significantly (P=0.22). Yet, the mean estimated washout rate at 4 hours pi derived from the acquisition at 2 hours pi showed a difference compared with the actual washout rate at 4 hours pi (25±19 vs. 34±17, P<0.001).
Conclusions: The direct comparison method for cardiac ¹²³I-MIBG imaging enables accurate estimation of the actual late H/M ratio and washout rate at 4 hours pi derived from the acquisitions at 3 hours pi. The acquisition at 2 hours pi should only be performed in exceptional cases when clinically necessary because of the existing difference between the actual and estimated washout rate at 4 hours pi derived from 2 hours pi.

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Purpose: The quantification of coronary flow reserve (CFR) calculated as the ratio of the myocardial blood flow (MBF) during adenosine triphosphate (ATP) stress to MBF at rest is a useful method for evaluating the functional severity of coronary artery disease (CAD) using ¹⁵O-H₂O positron emission tomography (PET). The shorter acquisition time may reduce dyspnea and other side effects of ATP stress and may also reduce the effect of body movements during data acquisition. However, the impact of the shorter data acquisition time on the accuracy of MBF quantification has not been studied. In this retrospective study, we evaluated the accuracy of the MBF and CFR values obtained with shorter scan times using ¹⁵O-H₂O PET.
Methods: Thirty patients suspected of having CAD (22 males, 8 females; age 56.5±8.8 yrs) and 17 healthy controls (17 males; age 27.7±6.2 yrs) underwent PET during rest and PET with ATP stress dynamic ¹⁵O-H₂O. The MBF was estimated with a one-tissue compartment model analysis. MBF and CFR values were calculated using the first 2-min and 3-min PET data of ¹⁵O-H₂O as shorter data acquisitions. These data were compared to the standard 6-min PET acquisition data.
Results: With the use of the 3-min data, the regions of interest (ROIs) in the left ventricular (LV) chamber and myocardium could be set for all of the subjects. The intraclass correlation coefficients (ICCs) between the 3-min data and 6-min data of the rest MBF, stress MBF and CFR were 0.869, 0.870, and 0.819 in the patients, and 0.912, 0.910, and 0.930 in the controls. The 3-min CFR data showed a significant difference between the patients and controls (2.22±1.02 vs. 4.02±1.50, p<0.01), as did the 6-min data (2.19±0.92 vs. 4.16±1.39, p<0.01). However, the CFR based on 2-min data did not show a significant difference (1.96±1.66 vs. 2.73±1.03, p=0.088). Using a receiver operating characteristic (ROC) analysis, we observed that both the 3-min and 6-min CFR data could be used to separate the CAD patients and controls.
Conclusions: A 3-min, but not 2-min, scan with ¹⁵O-H₂O PET can be used for the quantitative evaluation of MBF and CFR.

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Background: The method of Segmentation with Scatter and Photopeak window data in Attenuation Correction (SSPAC) recognizes the outlines of the body around chest and lungs using scatter window data after which an attenuation correction (μ) map can be constructed. We have developed a new extraction method, adding a masking process to SSPAC, because the extraction of outlines was otherwise incomplete.
Methods and Results: The masking process extracted right and left lung fields from chest images.The quality of the masking process was confirmed by the results from a low count phantom.In a case study, automatic extraction by SSPAC had a 44% success rate for low count (stress condition) myocardial single-photon emission computed tomography (SPECT) images, but reached a success rate of 99% with the addition of the new masking process. Outline truncation and low counts can cause unsuccessful SSPAC.
Conclusions: Our method for masking will contribute to a widespread use of SSPAC by improving the success rate in contouring.

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Backgrounds: Myocardial single-photon emission computerized tomography (SPECT) with the patient in the prone position has recently been applied to improve the percentage uptake (%uptake) in the inferior wall by reducing diaphragmatic attenuation. We hypothesized that the type of stress might cause a difference in the %uptake improvement in inferior regions in the prone position. The purpose of this study was to compare the %uptake improvement between exercise and pharmacological vasodilator stress in prone myocardial SPECT.
Methods: Following a SPECT study in the supine position, a second SPECT study was performed in the prone position. The cases of 41 patients were studied prospectively: 21 patients with pharmacological stress and 20 with exercise stress. A segmental %uptake based on the quantification of a polar map was used. Liver and heart average counts were measured with a supine planar image. The correlation between the liver-to-heart ratio and the %uptake increase in the inferior wall was then examined.
Results: Pharmacological stress showed a significantly higher average %uptake increase in the inferior wall compared to exercise stress (5.59±2.86% vs. 3.18±1.84%, p<0.05). The average liver-to-heart ratio was significantly higher in pharmacological than in exercise stress (1.04±0.40% vs. 0.72±0.22%, p<0.01). As the liver-to-heart ratio increased, the %uptake increase in the inferior wall increased (y=5.54x -0.51, r=0.74; p<0.05).
Conclusions: Pharmacological stress in the prone position showed greater increase in the %uptake in the inferior wall compared to the exercise-stress patients, mainly due to the higher liver uptake in the former group.

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For the numerous cardiology clinical practices in Japan, nuclear cardiology imaging tests are among the most important diagnostic tools. The Japanese nuclear cardiology community has developed a new application using ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) to diagnose cardiac sarcoidosis, as well as new diagnostic imaging tests using ¹²³I-beta-methyl-p-iodophenyl-pentadecanoic acid (BMIPP) and ¹²³I-metaiodobenzylguanidine (MIBG). These new approaches have become popular worldwide. The Japanese Circulation Society (JCS) and the Japanese Society of Nuclear Cardiology (JSNC) have published clinical imaging guidelines and recommendations showing indications and standards for the new imaging tests. Current nuclear cardiology clinical practices in Japan may provide new insights for nuclear cardiology worldwide.

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Positron emission tomography (PET) has greater temporal and spatial resolution. ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) PET has also been used to assess pathophysiological condition and to identify the patients who have benefit from coronary revascularization therapy in ischemic left ventricular dysfunction. There have been numbers of studies looking at the diagnostic value of viable myocardium using ¹⁸F-FDG PET. However, the prospective trials have been very limited and has been no previous study prospectively conducted by multi-center. Recently, the prospective multicenter clinical study in Japan showed the diagnostic usefulness of ¹⁸F-FDG in predicting improvement in myocardial wall motion after coronary revascularization. This study has great contribution to strength the evidence of ¹⁸F-FDG PET for detecting viable myocardium. Nuclear approach, including FDG-PET, can be a useful tool to identify viability in case of difficult to diagnose myocardial viability using myocardial perfusion SPECT. (Ann Nucl Cardiol 2016)

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In this issue of the journal, Dimitriu-Leen et al. addressed a question of whether an early late imaging (e.g., 1, 2, or 3 hours after tracer injection) can be used as an alternative to 4 hour ¹²³I-MIBG imaging in terms of heart-to-mediastinum uptake ratio (HMR) and washout rate (WR). They found that, by applying the linear regression model, HMR and WR obtained at 3 hours after injection can accurately estimate those at 4 hours. Additionally, the parameters estimated at 2 hours showed a close correlation to those at 4 hours. This study shows that a shorter imaging protocol is feasible without loss of clinical significance as compared to 4 hour imaging, which is certainly more convenient for the patients. More importantly, collected ¹²³I-MIBG imaging data from different acquisition protocols can directly be compared and exchangeable. Because we now have tools for standardization of data derived from different camera systems, the results of this study would further facilitate the use of ¹²³I-MIBG imaging as a reliable aid for risk stratification of HF patients.

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¹⁵O-water has been considered to be a near-perfect and the most ideal myocardial blood flow (MBF) tracer because it is freely diffusible, metabolically inert, and independent of the myocardial metabolic state, which results in the highest extraction fraction. Absolute coronary flow reserve (CFR) is the ratio of MBF during maximal hyperemia in a coronary artery to MBF in the same artery under resting conditions and can be quantified noninvasively by positron emission tomography (PET). A growing body of literature is accumulating to show that the prognostic value of absolute MBF or CFR, which is quantified by cardiac PET.

ATP infusion protocol of 0.16 mg/kg/min for 5 minutes and its safety profile have been established in humans and it has been widely applied in many clinical and investigative studies including ¹⁵O-water PET. With the use of the 3-min acquisition data, the regions of interest in the left ventricular chamber and myocardium could be set for all of the subjects. Six-min CFR data could be used to separate the CAD patients and controls. A 3-min, but not 2-min, scan with ¹⁵O-water PET can be used for the quantitative evaluation of MBF and CFR. A shorter scan time will result in a reduction of body motion of patients, which may lead to the more precise quantification of MBF and CFR.

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Primary cardiac tumors are rare. Myxoma and sarcoma are the most common types of benign and malignant cardiac tumors, respectively. Secondary cardiac tumors, the majority of which are metastases, are more common than primary tumors. The use of an appropriate combination of cardiovascular imaging techniques is necessary for the differential diagnosis of cardiac tumors and for preoperative examinations aimed at assessing tumor mobility and the positional relationship between the tumor and the surrounding normal structures, such as valves, papillary muscle, etc. The various components of cardiac tumors, such as fibrosis, lipids, hemorrhaging,necrosis, and degenerative changes, can be identified based on their signal intensity on magnetic resonance imaging (MRI), whereas cine-MRI is useful for assessing tumor mobility. Computed tomography is the optimal modality for identifying calcification, and intravenous contrast agent injection is useful for evaluating tumor vascularity. Fluorodeoxyglucose (FDG)-positron emission tomography (PET) plays an important role in the differentiation of malignant tumors from benign ones. Malignant cells utilize more glucose than benign cells.

Thus, malignant cardiac tumors exhibit more intense FDG uptake than benign tumors. PET/MRI scanners are a recently developed type of clinical imaging system that can obtain morphological, histopathological, functional,and metabolic information in a single session. To suppress physiological myocardial FDG uptake, long-term fasting; the injection of heparin; and the administration of a high fat, low carbohydrate diet can be employed before PET scans.

Herein, we review the imaging features of cardiac tumors and present clinical images of cardiac diseases that were obtained at our institution.

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Recent developments in nuclear medicine technology have been remarkable, with new technologies emerging in both hardware and software. In this study, we focused on an image reconstruction method known as the ordered subset conjugate gradient minimizer (OSCGM) method. We conducted a myocardial phantom experiment and a clinical study to examine the difference between this technology and conventional methods as well as the characteristics of an IQ-SPECT system with this technology. The outline is shown.

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Background: Cardiac ¹³N-ammonia (¹³N-NH₃) positron emission tomography (PET) is approved by Japanese Ministry of Health, Labour and Welfare for diagnosis of ischemic heart disease. New PET camera recently has three-dimensional mode acquisition and ordered subset expectation maximization (OSEM) reconstruction with time-of-flight (TOF) and point spread function (PSF) correction technology. The aim of the phantom study was to evaluate the usefulness of this novel technology using ¹³N-NH₃ and ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG).

Method: PET imaging was performed using a lung-heart torso phantom with myocardial perfusion defects. The indices of defect contrast, the coefficient of variation (CV) and the index of homogeneity were analyzed by using four reconstruction schemes, including OSEM, OSEM+TOF, OSEM+PSF, and TOF+PSF correction methods.

Results: The phantom study showed that TOF resulted in improvements of defect lesion detectability with low statistical noise. The defect contrast index of TOF+PSF was significantly larger than that of OSEM only (p=0.048). The cardiac percent root mean square uncertainty (RMSU) with PSF was 25.9% in OSEM+PSF and 20.9% in TOF+PSF. In contrast cardiac % RMSU without PSF correction was 14.8% in OSEM and 15.3% in TOF, which was lower than that with PSF correction. The average wall counts were homogeneous in four reconstruction methods in ¹³N-NH₃. The value of % CV on the profile curve of ¹³N-NH₃ images was confirmed to be smaller than 5% in all reconstruction methods.

Conclusions: The new PET technology with TOF and PSF correction may extend the possibility of precise analysis of abnormal perfusion defects, and clinical applications are expected.

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Cardiac magnetic resonance (CMR) is a rapidly evolving technology that is increasingly being used for the noninvasive imaging in the diagnosis of cardiac diseases. CMR allows for the accurate and reproducible assessments of anatomy, function and tissue characterization of the heart. It is important for cardiologists to know the advantages and the clinical applications of CMR examination. This review article describes the essentials of CMR study and the key points of the interpretation in patients with cardiac disease.

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With the introduction of the concurrent myocardial blood flow (MBF) quantification in ml/g/min with positron emission tomography/computed tomography (PET/CT) assessment of myocardial perfusion in clinical routine, the scope of conventional scintigraphic myocardial perfusion imaging now expands from the identification of the most advanced and culprit CAD lesion, as signified by the stress-induced regional myocardial perfusion defect, also to less severe but flow-limiting stenosis in multivessel CAD. Thus, by adding regional MBFs determined at rest and during vasomotor stress with the resulting myocardial flow reserve (MFR=MBF during stress/MBF at rest) to conventional myocardial perfusion PET/CT, a comprehensive identification and characterization of flowlimiting effects of multivessel CAD has become feasible. The non-specific nature of the hyperemic MBF increase and MFR, however, necessitates an evaluation and interpretation of regional hyperemic MBFs in the appropriate context with coronary morphology, microvascular function, and wall motion analysis in patients with CAD. Such a diagnostic approach may foster a more individualized and image-guided decision making process towards coronary revascularization procedures in patients with complex multivessel CAD that, however, remains to be tested in clinical outcome studies.

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Biomarkers are used for evaluation of the pathophysiological state, risk stratification, diagnostic tools, staging of a disease and responsiveness to treatment. Representative biomarkers used in cardiovascular diseases may include C-reactive protein (CRP) for inflammation, brain natriuretic peptide (BNP), atrial natriuretic peptide (ANP), aldosterone, renin for neurohumoral factors, plasminogen activator inhibitor type-1 (PAI-1) for fibrinolysis and endothelial function, d-dimer for thrombosis, urine albumin/creatinine ratio for renal glomerular endothelial function. Further addition of new biomarkers may increase the capacity to find high-risk patients with cardiovascular diseases. In this review we would like to introduce several representative biomarkers in the context of nuclear cardiology. With the advancement of new imaging modalities new biomarkers are readily available. Combined use of new nuclear cardiology modalities with biomarkers one would establish prevention guidelines and classify high-risk subgroups needing treatment intervention.

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Myocardial perfusion positron emission tomography (PET) has long been regarded as a gold standard of myocardial blood flow (MBF) measurement. However, since randomized clinical trials showed the prognostic value of fractional flow reserve (FFR)-guided revascularization, FFR has rapidly become a new gold standard of functionally significant coronary artery disease (CAD). Despite the predominance of FFR in the management of stable CAD, FFR also has limitations. Overcoming hurdles by the lesion-specific MBF measurement by hybrid imaging and novel flow parameter can be a complimentary tool.

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Myocardial blood flow (MBF) quantification with PET is generally considered a gold standard for the measurement of myocardial perfusion in absolute terms. The resulting values of MBF and myocardial flow reserve (MFR) used to determine the diagnostic path of a patient have a twofold (for MFR) or threefold (for MBF) range in literature, which interferes with establishing meaningful cutoffs－numeric values to tell healthy tissues from sick.

The review discusses software-based causes of variation of the quantification values that can be introduced at various steps of an image analysis－reconstruction, segmentation, quality control, tracer kinetic modelling, and outputting the resulting values. The review discusses possible solutions as well as the future of myocardial blood flow quantification software development.

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This article gives an overview of essential requirements and limitations in the quantitative assessment of regional myocardial perfusion or regional myocardial blood flow (rMBF) using existing clinical SPECT systems in clinical settings. One major requirement is the need for acquiring complete projection data without truncation. Attenuation and scatter are then prerequisites to reproduce quantitative images which should represent regional distribution of true radioactivity concentration in the myocardium. A compartmental model could then be applied to extract physiological myocardial perfusion from series of tomographic images acquired following i.v. radio ligand administration. There are also requirements in the radio-ligands if one wish to estimate quantitative blood flow for a physiologicaly wide range of flow. The most important factor is need for a high first-pass extraction fraction. Several factors that affect quantitative ability are reviewed and their importance is illustrated by example.

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Cadmium-zinc-telluride (CZT) solid-state detectors have recently been introduced to myocardial single-photon emission computed tomography (SPECT) imaging. In this camera system, the conventional sodium iodide crystals have been replaced by CZT semiconductors, which directly convert radiation into electric signals. The energy resolution and spatial resolution have been significantly improved and the reduction of the acquisition time or radiotracer dose has been reported based on several studies. Two types of CZT camera system have been introduced in Japan: Discovery NM530c (GE Healthcare, Haifa, Israel) and D-SPECT (Spectrum Dynamics, Caesarea, Israel). With these new semiconductor systems, various study protocols for stress myocardial perfusion imaging (MPI) have been developed in Japanese institutions using different radioisotopes such as thallium-201 or technetium-99m radiotracers. In addition, not only quality of SPECT image but also diagnostic performance of this ultrafast camera system for Japanese patients has been evaluated.

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The Discovery NM530 is a new generation of SPECT cameras equipped with semiconductor cadmium-zinc-telluride (CZT) detector technology. It provides a shorter scan time and reduces the patient’s radiation exposure wthout loss of image quality compared with the conventional Anger camera. Combined supine and prone imaging with the Discovery NM530c is usefulfor reducing the false-positive rate in the infero-posterior or infero-lateral segment associated with supine imaging. As studied by multicenter registry, 74% sensitivity, 85% specificity, and 81% accuracy for left anterior descending coronary artery stenosis, 76% sensitivity, 89% specificity, and 85% accuracy for left circumflex coronary artery stenosis, and 72% sensitivity, 86% specificity, and 82% accuracy for right coronary artery stenosis were observed in detecting an angiographic diameter narrowing of ≥75% on visual estimation. Using a low-dose technetium-99m (185/370 MBq) 1-day protocol with an effective dose of ≤5 mSv, CZT SPECT demonstrated an acceptable diagnostic yield in detecting a significant coronary stenosis as assessed by fractional flow reserve (FFR). As for limiting to 92 coronary lesions in which FFR was measured, stress SPECT showed 77% sensitivity, 91% specificity, and 84% accuracy, whereas the diagnostic value decreased to 52% sensitivity, 68% specificity, and 58% accuracy based only on visual estimation of ≥75% diameter narrowing. In addition, the quantification of myocardial perfusion reserve derived by dynamic SPECT imaging using the Discovery NM530c may help identify balanced ischemia in patients with left main or 3-vessel disease.

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Novel single photon emission computed tomography (D-SPECT) scanners with solid-state semiconductor detectors using cadmium zinc-telluride (CZT) have been clinically applied. D-SPECT is a second scanner in Japan in which CZT detectors offer higher sensitivity and better spatial resolution than conventional Anger cameras. Myocardial counts are important to assure image quality that might be improved due to the favorable physical performance of the CZT detectors. Different physical properties between CZT detectors and Anger cameras alter the quality of myocardial SPECT images. The image quality of ²⁰¹Tl-SPECT improved after introducing CZT detectors to achieve that of ^99mTc. In addition, results from ECG-gated myocardial SPECT in clinical practice such as left ventricular volumes and ejection fraction were similar. These results could be applied to patients in the same way as those of conventional Anger cameras. However, reverse redistribution appears myocardial ²⁰¹Tl-SPECT images of apparently normal persons. Uptake in apical areas is sometimes reduced. In conclusion, myocardial perfusion scintigraphy with ²⁰¹Tl and CZT detectors has been clinically applied in Japan. Some ²⁰¹Tl data from gamma cameras and CZT detectors are identical, but others differ. Further investigation is needed to optimize myocardial perfusion scintigraphy with ²⁰¹Tl.

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Cardiac sympathetic dysfunction is closely associated with risk of cardiac events in heart failure (HF), indicating HF progression and sudden cardiac death by lethal ventricular arrhythmia. For cardiac sympathetic nervous system imaging, ¹²³I-meta-iodobenzylguanidine (MIBG), among other agents, has been approved by the Japanese health and welfare ministry and is widely used in clinical settings. ¹²³I-MIBG was also approved by the Food and Drug Administration (FDA) in the United States of America (USA) and is expected to achieve broad acceptance. In Europe. ¹²³I-MIBG is currently used only for clinical research. Given the current situation, the American Society of Nuclear Cardiology (ASNC) and the Japanese Society of Nuclear Cardiology (JSNC) are preparing to issue clinical guidelines for ¹²³I-MIBG imaging in Ann Nucl Cardiol.

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¹²³Iodine-meta-iodobenzylguanidine (¹²³I-MIBG) imaging can visualize cardiac sympathetic innervation by providing (semi-) quantitative information on the myocardial sympathetic activity.

Although there are lots of prognostic studies in patients with heart failure, clinical application of cardiac ¹²³I-MIBG outside Japan is still limited. However, the number of potential clinical indications for ¹²³I-MIBG imaging is growing as autonomic dysfunction is also present in other cardiac diseases.

The present review gives an overview of the potential clinical cardiac indications beyond heart failure of ¹²³I-MIBG imaging to evaluate the cardiac sympathetic activity. The focus of the manuscript is primarily based on studies that have been performed outside Japan.

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An excess, long-lasting increase in systemic autonomic function facilitates myocardial injury and heart failure (HF), leading to lethal cardiac outcomes. Cardiac ¹²³I-labeled metaiodobenzylguanidine (MIBG) imaging enables non-invasive and quantitative evaluation of cardiac sympathetic innervation in human hearts. The independent and incremental prognostic values of this imaging technique in combination with clinical information in chronic HF patients have been shown. Results of recent multicenter MIBG studies performed in North-America, Europe and Japan have further strengthened the prognostic values, facilitating the clinical use of cardiac MIBG imaging in long-term management of chronic HF patients. Cardiac neuroimaging can contribute not only to the risk-stratification for lethal events but also to appropriate selection of a therapeutic strategy using drug and device therapies, such as implantable cardioverter defibrillator (ICD) implantation and cardiac resynchronization therapy (CRT), in HF patients. Because of the limitations of current indication criteria, however, some patients undergoing ICD implantation and/or CRT receive no potentially beneficial intervention and, in contrast, some other patients have lethal outcomes without the benefits. Because of increases in medical costs due to non-effective or futile device therapy, the non-negligible number of non-responders to device treatment indicates the need for better selection of high-risk patients who can benefit most from device treatment in a cost-effective manner. Quantitative assessment of cardiac MIBG activity and kinetics can improve the identification of potential candidates for ICD/CRT and reduce costs associated with device treatments with a minimal impact on outcomes. A further large-scale investigation is needed to establish the possibility of cardiac MIBG imaging for more precisely selecting patients at increased risk or at low risk for potentially lethal arrhythmias, sudden cardiac death and/or refractory pump failure so as to optimize therapeutic interventions in patients with heart failure.

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¹²³I-meta-iodobenzylguanidine (MIBG) is a potent prognostic marker of chronic heart failure (CHF). However, inter-institutional variations due to methodological variations required minimization before ¹²³I-MIBG findings could be universally applied to the diagnosis, treatment and prognosis of CHF. Therefore, protocols including data acquisition, setting regions of interest for calculating heart-to-mediastinum ratios (HMR) and cross-calibration of HMR among institutions required standardization. A cross-calibration phantom was introduced to overcome institutional differences, and a large amount of experimental data were collected, which enabled multicenter comparisons and the creation of large-scale prognostic databases. Thereafter, cardiac mortality risk models to estimate short- and long-term (two and five years, respectively) mortality were created based on a standardized ¹²³I-MIBG HMR. The ability of these models to accurately determine prognosis is currently undergoing validation.

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In a polar map display, the LAD originates from an area corresponding to 11 o’clock, and the relationship between localization of the culprit lesion and diagonal arteries can be inferred by the extent of decreased perfusion extending from 12 o’clock towards 1 o’clock. The location of a lesion in the LCX main trunk can be inferred by whether decreased perfusion is observed at any level within 2〜5 o’clock. Infarction volume depends on the anatomical size of the territories of the PD and AV but not on the location of a culprit lesion in the RCA trunk.

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Myocardial perfusion imaging (MPI) reports play a critical role in communicating results to referring physicians. A well-structured report is succinct, easy to understand and guides physicians in appropriate decision-making. Although the structure of MPI reports may differ across institutions and countries, they serve a common goal of informing the referring physician. In Japan, there are no standard reporting guidelines. However it is desirable to follow standards published in peer-reviewed consensus statements and guidelines. We review current North American reporting methods in hopes that can better guide trainees and imaging physicians toward simple standardized and informative MPI reports that will ultimately improve patient care.

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Choosing the appropriate modality is important for diagnosis of ischemic heart disease in clinical settings. The Appropriate Use Criteria (AUC) were published by the American College of Cardiology Foundation along with key specialty and subspecialty societies. The AUC provides information on which modality is “appropriate” according to various clinical situations, and is widely utilized especially in the United States. In this article, we introduce “2013 Multimodality Appropriate Use Criteria for the Detection and Risk Assessment of Stable Ischemic Heart Disease”.

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Developing novel nuclear cardiology approaches requires evaluating their diagnostic ability. Statistical measures such as sensitivity, specificity, receiver operating characteristic (ROC) curve, and area under the curve (AUC) are useful to evaluate the diagnostic value of novel imaging parameters. This paper reviews key statistical methods used in the evaluation of diagnostic tests and highlights their use in clinical research settings.

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Nuclear cardiology certification was developed under the Certification Board of Nuclear Cardiology (CBNC) to provide practice-based requirements against which the members of the profession can be assessed. The purposes of the CBNC certification program are to 1) establish the domain of the practice of nuclear cardiology for certification; 2) to assess the level of knowledge demonstrated by nuclear cardiology specialists in a valid manner; 3) to encourage professional growth in, and enhance the quality of, the practice of nuclear cardiology; 4) to recognize formally individuals who meet the requirements for nuclear cardiology certification; and 5) to serve to public by encouraging quality patient care in the practice of nuclear cardiology. Certifying nuclear cardiology specialists from cardiology, nuclear medicine and radiology since 1996, the credential is viewed as essential for many would-be practitioners of the specialty as they complete their training (1).

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Fellows-in-training (FITs) and early career physicians with particular interest in cardiovascular imaging have a multitude of professional society ‘homes’ available to them. Determining the value of professional society membership and the ultimate choice of which to join can be difficult. A framework including honest assessment of personal expertise and candidate societies’ track record of educational output, structured leadership development, and forward-thinking strategic planning can be helpful in decision-making related to this critical component of early career development.

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In each year, Japanese Society of Nuclear Cardiology (JSNC) recognizes and rewards an outstanding investigator who is making great contributions to the advancement of nuclear cardiology. From 2000 to 2016, seventeen researchers have received the JSNC award. In the award presentation session in the annual JSNC scientific meeting, the audience can encounter the latest and excellent research achievements in the field of nuclear cardiology. This award lecture session is one of the highlights of annual JSNC meeting. This article provides JSNC members with key research topics covered in recent-3 year JSNC award, including assessment of myocardial dysfunction with ^99mTc-sestamibi imaging, prognostic values of ¹²³I-MIBG imaging and quantitative assessment of myocardial blood flow using cardiac positron emission tomography (PET).

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The Young Investigator Award (YIA) competition session is one of the highlights of the Japanese Society of Nuclear Cardiology (JSNC) annual scientific meeting. Beginning in 2014, the top 3 abstracts submitted to the JSNC annual meeting by candidates under the age of 40 have been considered for the YIA. At the 2015 YIA session, these candidates presented abstracts on the latest important research topics in nuclear cardiology. These topics included phase analysis in chronic kidney disease, cardiac sarcoidosis, and risk assessment using myocardial perfusion imaging.

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Noninvasive quantification of regional myocardial blood flow (MBF) and coronary flow reserve (CFR) by myocardial perfusion positron emission tomography/computed tomography (PET/CT) imaging is well-established and has additional diagnostic value over traditional visual analysis. A growing need for high sensitivity and high spatial resolution capable of assessing smaller targets with shorter acquisition time has led to technical advancements. These include whole-body imaging, 3-dimensional (3D) mode acquisition, application of new scintillator materials, and iterative reconstruction algorithms. Among these advancements, the combination of 3D mode acquisition and time-of-flight (TOF) technology has played an important role in clinical oncology PET/CT studies. In this review, I summarized studies that have focused on the use of TOF PET/CT with ¹³N-ammonia (¹³N-NH₃). Compared with conventional PET acquisition, the combination of 3D mode acquisition and the TOF imaging can improve noise and image quality in ¹³N-NH₃ perfusion imaging. As a result, it yields high reproducibility and accurate measurement of CFR.

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The 5^th edition of our book “nuclear cardiac imaging: principles and applications” is written to encompass the vast new developments in cardiac imaging. To accomplish this we solicited contributions of seasoned authors who have gone beyond updating what was in 4^th edition by rewriting literally every single chapter. There is also consistency in the format as each chapter starts with 10 key points and many are supplemented by real life case presentations to highlight specific points. The electronic version provides easy access to download power point slides from high quality color figures and tables and access to references linked to PubMed. Each chapter was read by the 2 editors and revised as needed. The book stands as a testimony to the hard work of all authors and as a service to the imaging community.

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