Equilibrium radionuclide angiography: Intra- and inter-observer repeatability and reproducibility in the assessment of cardiac systolic and diastolic function

Software Discrepancies in Radionuclide-Derived Left Ventricular Ejection Fraction

Gated equilibrium radionuclide angiography (ERNA), or multigated acquisition scanning, is a well-established technique to monitor left ventricular ejection fraction (LVEF) in patients treated with potentially cardiotoxic chemotherapy. To determine the results of a true change in LVEF, low inter- and intrareader variability is important. The aim of this study was to investigate inter- and intrareader variability in LVEF measurements using 2 different commercially available software packages with cardiac MR (CMR) as a reference standard. Methods: In 46 ERNA scans, LVEF was measured by 2 experienced nuclear medicine technologists, using the 2 software packages Xeleris and Corridor4DM. All patients had CMR performed within 1.5 h from ERNA. CMR-derived LVEF was measured by a cardiologist using cvi42 software. Eight patients were reanalyzed to investigate intrareader variability. Bland-Altman analysis was used to assess agreement between readers and software. Repeated-measures ANOVA was used to assess interactions between readers and software. Differences in mean LVEF were compared using a t test. The Lin concordance correlation coefficient (CCC) was used to test LVEF agreement between software packages and readers and the reference CMR results. Results: Corridor4DM had a significantly higher mean LVEF than did Xeleris. No significant interreader difference was observed within the same software. ANOVA found that readers did not influence LVEFs. The CCC between software packages was similar for both readers, at 0.409 for reader 1 and 0.418 for reader 2. Both software packages showed a significant LVEF bias compared with CMR (4% for Xeleris vs. 11% for Corridor4DM). For both readers, the CCC for correlation with MRI was higher for Xeleris (0.438/0.572) than for Corridor4DM (0.257/0.244). Conclusion: A high degree of variability was found between the 2 different software packages for the calculation of LVEF. No significant difference in LVEF was found between readers using the same software. Corridor4DM gave higher LVEF estimates than did Xeleris. Our findings suggest that different software programs for assessing LVEF in ERNA examinations are not interchangeable. The utmost caution is recommended if switching between different types of software.

Fully Automatic Quantitative Measurement of Equilibrium Radionuclide Angiocardiography Using a Convolutional Neural Network

PURPOSE

The aim of this study was to generate deep learning-based regions of interest (ROIs) from equilibrium radionuclide angiography datasets for left ventricular ejection fraction (LVEF) measurement.

PATIENTS AND METHODS

Manually drawn ROIs (mROIs) on end-systolic and end-diastolic images were extracted from reports in a Picture Archiving and Communications System. To reduce observer variability, preprocessed ROIs (pROIs) were delineated using a 41% threshold of the maximal pixel counts of the extracted mROIs and were labeled as ground-truth. Background ROIs were automatically created using an algorithm to identify areas with minimum counts within specified probability areas around the end-systolic ROI. A 2-dimensional U-Net convolutional neural network architecture was trained to generate deep learning-based ROIs (dlROIs) from pROIs. The model's performance was evaluated using Lin's concordance correlation coefficient (CCC). Bland-Altman plots were used to assess bias and 95% limits of agreement.

RESULTS

A total of 41,462 scans (19,309 patients) were included. Strong concordance was found between LVEF measurements from dlROIs and pROIs (CCC = 85.6%; 95% confidence interval, 85.4%-85.9%), and between LVEF measurements from dlROIs and mROIs (CCC = 86.1%; 95% confidence interval, 85.8%-86.3%). In the Bland-Altman analysis, the mean differences and 95% limits of agreement of the LVEF measurements were -0.6% and -6.6% to 5.3%, respectively, for dlROIs and pROIs, and -0.4% and -6.3% to 5.4% for dlROIs and mROIs, respectively. In 37,537 scans (91%), the absolute LVEF difference between dlROIs and mROIs was <5%.

CONCLUSIONS

Our 2-dimensional U-Net convolutional neural network architecture showed excellent performance in generating LV ROIs from equilibrium radionuclide angiography scans. It may enhance the convenience and reproducibility of LVEF measurements.

Tales from the future-nuclear cardio-oncology, from prediction to diagnosis and monitoring

Cancer and cardiovascular diseases (CVD) often share common risk factors, and patients with CVD who develop cancer are at high risk of experiencing major adverse cardiovascular events. Additionally, cancer treatment can induce short- and long-term adverse cardiovascular events. Given the improvement in oncological patients' prognosis, the burden in this vulnerable population is slowly shifting towards increased cardiovascular mortality. Consequently, the field of cardio-oncology is steadily expanding, prompting the need for new markers to stratify and monitor the cardiovascular risk in oncological patients before, during, and after the completion of treatment. Advanced non-invasive cardiac imaging has raised great interest in the early detection of CVD and cardiotoxicity in oncological patients. Nuclear medicine has long been a pivotal exam to robustly assess and monitor the cardiac function of patients undergoing potentially cardiotoxic chemotherapies. In addition, recent radiotracers have shown great interest in the early detection of cancer-treatment-related cardiotoxicity. In this review, we summarize the current and emerging nuclear cardiology tools that can help identify cardiotoxicity and assess the cardiovascular risk in patients undergoing cancer treatments and discuss the specific role of nuclear cardiology alongside other non-invasive imaging techniques.

Nuclear medicine in the assessment and prevention of cancer therapy-related cardiotoxicity: prospects and proposal of use by the European Association of Nuclear Medicine (EANM)

Cardiotoxicity may present as (pulmonary) hypertension, acute and chronic coronary syndromes, venous thromboembolism, cardiomyopathies/heart failure, arrhythmia, valvular heart disease, peripheral arterial disease, and myocarditis. Many of these disease entities can be diagnosed by established cardiovascular diagnostic pathways. Nuclear medicine, however, has proven promising in the diagnosis of cardiomyopathies/heart failure, and peri- and myocarditis as well as arterial inflammation. This article first outlines the spectrum of cardiotoxic cancer therapies and the potential side effects. This will be complemented by the definition of cardiotoxicity using non-nuclear cardiovascular imaging (echocardiography, CMR) and biomarkers. Available nuclear imaging techniques are then presented and specific suggestions are made for their application and potential role in the diagnosis of cardiotoxicity.

Shining Damaged Hearts: Immunotherapy-Related Cardiotoxicity in the Spotlight of Nuclear Cardiology

The emerging use of immunotherapies in cancer treatment increases the risk of immunotherapy-related cardiotoxicity. In contrast to conventional chemotherapy, these novel therapies have expanded the forms and presentations of cardiovascular damage to a broad spectrum from asymptomatic changes to fulminant short- and long-term complications in terms of cardiomyopathy, arrythmia, and vascular disease. In cancer patients and, particularly, cancer patients undergoing (immune-)therapy, cardio-oncological monitoring is a complex interplay between pretherapeutic risk assessment, identification of impending cardiotoxicity, and post-therapeutic surveillance. For these purposes, the cardio-oncologist can revert to a broad spectrum of nuclear cardiological diagnostic workup. The most promising commonly used nuclear medicine imaging techniques in relation to immunotherapy will be discussed in this review article with a special focus on the continuous development of highly specific molecular markers and steadily improving methods of image generation. The review closes with an outlook on possible new developments of molecular imaging and advanced image evaluation techniques in this exciting and increasingly growing field of immunotherapy-related cardiotoxicity.