Annals of nuclear cardiology最新文献

The Japanese Society of Nuclear Cardiology (JSNC) and the American Society of Nuclear Cardiology (ASNC) has a cooperative relationship through a memorandum of understanding (MOU), based on which we hold a joint symposium in the JSNC annual meeting in early summer. In addition to the joint symposium this year, a joint webinar was held in early June. The theme of the joint symposium and webinar was cardiac amyloidosis. We consider the success of this collaborative work to be the fruit of the close friendship between JSNC and ASNC. The cooperative relationship between JSNC and ASNC will continue to grow.

Background: The myocardial perfusion stress conducted by physicians and nurses requires two imaging sessions, one during stress and the other during rest. Echocardiography is sometimes performed before delayed imaging, and medical laboratory technicians (MLTs) have similar exposure in such cases. This study was designed to investigate the radiation exposure of physicians, nurses, radiologists, and MLTs involved in thallium-201 chloride (²⁰¹TlCl) stress myocardial perfusion imaging and echocardiography, the details of which have not been reported to date. Methods: The dose rate at thallium-201 (²⁰¹Tl) was examined using a cylindrical phantom. The exposure of physicians, nurses, and radiologists involved in the ²⁰¹TlCl stress myocardial perfusion imaging was measured using pocket dosimeters, and that of the MLTs in charge of echocardiography were measured using glass-batch dosimeters. Results: The attenuation of radiation exposure from the phantom with distance was 95% at 50 cm from the center of the phantom, demonstrated that the attenuation of the exposure dose increased with distance. The exposure dose for physicians, nurses, and radiological technologists that participated in ²⁰¹TlCl stress myocardial perfusion imaging was 0.20-0.23 μSv per exam, whereas it was 6.67-10.00 μSv per exam for MLTs. Conclusion: This study measured the dose received by physicians, nurses, and radiological technologists during stress MPI and the dose received by MLTs during echocardiography. The results provided advanced knowledge for the management of dose received by medical personnel.

Background: In cardiomyopathy, ^99mTc-MIBI washout can reflect mitochondrial dysfunction and late gadolinium enhancement (LGE) on cardiac magnetic imaging (MRI) is associated with tissue fibrosis. We sought to determine the relationship between ^99mTc-MIBI uptake, ^99mTc-MIBI washout, and LGE on MRI in patients with cardiomyopathy. Methods: Twenty-one patients underwent rest myocardial perfusion scintigraphy at 45 minutes (early) and 4 hours (delayed) after intravenous ^99mTc-MIBI administration and cardiac MRI. We assessed myocardial perfusion, ^99mTc-MIBI washout, and LGE. We divided the left ventricle (LV) wall into 16 segments using a polar map. Then, we classified each segment into 5 groups according to ^99mTc-MIBI uptake in early-rest images and washout. Additionally, we created a contingency table based on LGE presence/absence in the groups. Results: We evaluated 336 segments in 21 patients. ^99mTc-MIBI uptake was decreased in 168 segments in the early-rest ^99mTc-MIBI images. ^99mTc-MIBI washout was observed in 108 segments with either normal perfusion or reduced perfusion in the early-rest ^99mTc-MIBI images. LGE was positive in 104 segments. A contingency table analysis with Fisher's exact test showed that LGE was observed significantly more frequently in the segments with decreased ^99mTc-MIBI uptake (p<0.001). In segments without a decreased ^99mTc-MIBI uptake, there was a significant correlation between increased ^99mTc-MIBI washout and the presence of LGE (p=0.033). Conclusions: In cardiomyopathy, the mitochondrial dysfunction in the early stage is shown as ^99mTc-MIBI washout, and fibrotic changes in the myocardium in advanced stages are shown as LGE on cardiac MRI. The severity of myocardial damage and the clinical stage of cardiomyopathy can be evaluated using multimodal imaging.

A 58-year-old asymptomatic man with electrocardiogram (ECG) abnormality was referred to our institution for cardiac exams. His ECG showed a bifascicular block, and the echocardiography demonstrated a wall motion abnormality in apex. Stress-rest myocardial perfusion imaging (MPI) showed a significant defect in anterior wall with partial redistribution at rest. He was suspected of having an anterior myocardial infarction (MI) and underwent cardiac catheterization. However, coronary angiography (CAG) revealed no significant coronary atherosclerosis. Cardiovascular magnetic resonance imaging (CMR) was performed to evaluate the extent of myocardial infarction. Late gadolinium enhancement (LGE) demonstrated a significant epicardial and midmyocardial LGE in the multiple site including anterior, anteroseptal, lateral, inferior wall, and basal right ventricle junction, which strongly indicated that the fibrosis was due to cardiac sarcoidosis (CS).A myocardial perfusion defect in anterior wall shown in the MPI revealed the fibrosis as an atypical finding mimicking anterior MI.

Background: The voxel size in ECG-gated myocardial SPECT (GSPECT) is a compromise between geometric resolution and count statistics with varying values and is rather inconsistent in different centers. We investigated the influence of typical acquisition matrix sizes for GSPECT on the reproducibility and accuracy of left ventricular function parameters using a dynamic heart phantom. Methods: Ten paired acquisitions, each pair with slightly different phantom positions, were obtained using identical imaging parameters except acquisition matrix: 128 × 128 matrix (3.3 mm voxel) and 64 × 64 matrix (6.6 mm voxel). In the next step, 128 × 128 data sets were compressed to an additional set of 64 × 64 matrix images. Results: Nominal value of left ventricular ejection fraction (LVEF) of the phantom was 67%. Both acquisition matrices led to significant overestimation of the LVEF. Overestimation was more pronounced in 64 × 64 than in 128 × 128 studies (79.8 ± 2.5% vs. 73.6 ± 1.4%, p<0.05). Calculated volumes were closer to the nominal values with 128 × 128 than with 64 × 64 studies. Variance showed a trend to be higher with 64 × 64 matrix, but the effect did not reach the level of statistical significance. Conclusions: LVEF overestimation and volume underestimation can be reduced by using finer matrix size without any negative effect on the reproducibility.

In recent years, the requirement for pharmacological stress myocardial perfusion imaging (SPECT) has increased, and adenosine stress testing is now the mainstream. Selective adenosine A2A receptor agonists will be applied clinically in the future. By selectively activating only A2A receptors, it can reduce complications such as bronchospasm, hypotension, and bradycardia, which have been problems with adenosine stress tests. In addition, since this drug can be administered in bolus injection, it has the advantage of being able to perform the test at one root.

The pandemic of Coronavirus disease 2019 (COVID-19) caused a substantial negative impact on patients with cardiovascular disease. The negative impact of the pandemic on daily clinical practices for cardiovascular diseases (CVD) cannot be underestimated. The CVD patients (without COVID-19 infection), whose diagnosis and treatment have been delayed or postponed by the pandemic, are victims of COVID-19. In this context, COVID-19 is a "syndemic" disease. Several studies already revealed that negative changes already occurred in CVD patient management, such as increased in-hospital death, supply shortage of ^99mTc/⁹⁹Mo generator, etc. To clarify the impact of COVID-19 on the management of CVD, a global survey named "INCAPS-COVID" was conducted. This study revealed a substantial reduction (around 50%) of cardiovascular imaging practice in the early stage of the pandemic during March and April 2020. This pandemic has necessitated changes in cardiovascular management practices to adopt this condition. Some of those changes will become the legacy of the pandemic. Possible legacy will be; 1) Use of telemedicine; 2) Shift from exercise to pharmacological stress; 3) Shift from single photon emission computed tomography (SPECT) to positron emission tomography (PET). By adapting and changing to the challenges caused by the COVID-19 pandemic, nuclear cardiology will survive and will rise as an improved cardiovascular practice, even after the pandemic.

Purpose/Method: Aliskiren is a direct renin inhibitor that has been reported to be effective for CHF, but the usefulness of combined therapy with carvedilol and aliskiren has not been reported. Forty-four patients with dilated cardiomyopathy (DCM) were randomized into a group receiving add-on therapy with carvedilol plus aliskiren and another group receiving carvedilol alone for 6 months. Nuclear imagings with ¹²³I-Metaiodobenzylguanidine (MIBG) and ^99mTc-Sestamibi were performed. Exercise capacity using a specific activity scale (SAS) and the New York Heart Association (NYHA) class were evaluated. Cardiac sympathetic nerve activity was evaluated by ¹²³I-MIBG imaging, with the delayed heart-to-mediastinum activity ratio (H/M), delayed total defect score (TDS), and washout rate (WR). Results: Combined add-on therapy with carvedilol and aliskiren improved several parameters much more than carvedilol alone (p<0.05) with respect to TDS, ejection fraction (EF), NYHA, SAS on 6 months and the changes in TDS, EF, end-diastolic volume and brain natriuretic peptide (BNP). Conclusion: Add-on therapy with carvedilol and aliskiren is more effective than carvedilol alone for improving cardiac sympathetic nerve activity, cardiac function, symptoms, exercise capacity, and brain natriuretic peptide in patients with DCM.