Cardiac Positron Emission Tomography-Magnetic Resonance Imaging: Current Status and Future Directions

Implications of uremic cardiomyopathy for the practicing clinician: an educational review

Studies over recent years have redeveloped our understanding of uremic cardiomyopathy, defined as left ventricular hypertrophy, congestive heart failure, and associated cardiac hypertrophy plus other abnormalities that result from chronic kidney disease and are often the cause of death in affected patients. Definitions of uremic cardiomyopathy have conflicted and overlapped over the decades, complicating the body of published evidence, and making comparison difficult. New and continuing research into potential risk factors, including uremic toxins, anemia, hypervolemia, oxidative stress, inflammation, and insulin resistance, indicates the increasing interest in illuminating the pathways that lead to UC and thereby identifying potential targets for intervention. Indeed, our developing understanding of the mechanisms of UC has opened new frontiers in research, promising novel approaches to diagnosis, prognosis, treatment, and management. This educational review highlights advances in the field of uremic cardiomyopathy and how they may become applicable in practice by clinicians. Pathways to optimal treatment with current modalities (with hemodialysis and angiotensin-converting enzyme inhibitors) will be described, along with proposed steps to be taken in research to allow evidence-based integration of developing investigational therapies.

Diagnosis and staging of cardiac masses: additional value of CMR with 18F-FDG-PET compared to CMR with CECT

PURPOSE

Characterization of malignant cardiac masses is usually performed with cardiac magnetic resonance (CMR) and staging with whole-body contrast-enhanced computed tomography (CECT). In this study, our objective was to evaluate the role of ¹⁸Fluor-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG-PET) with CMR for both characterization and staging of cardiac masses.

METHODS

Patients with cardiac masses who underwent CMR, CECT, and ¹⁸F-FDG-PET were retrospectively identified. For the characterization of cardiac masses, we calculated the respective performances of CMR alone, ¹⁸F-FDG-PET alone, and the combination of ¹⁸F-FDG-PET and CMR. For staging, we compared head-to-head the respective performances of ¹⁸F-FDG-PET and CECT. Histology served as gold standard for malignancy, and response to anticoagulation for thrombus.

RESULTS

In a total of 28 patients (median age 60.5 years, 60.7% women), CMR accurately distinguished malignant from benign masses with sensitivity (Se) of 86.7%, specificity (Sp) of 100%, positive predictive value (PPV) of 100%, negative predictive value (NPV) of 86.7%, and accuracy of 92.9%. ¹⁸F-FDG-PET demonstrated 93.3% Se, 84.6% Sp, 87.5% PPV, 91.7% NPV, and 89.3% accuracy. Combining CMR with ¹⁸F-FDG-PET allowed to benefit from the high sensitivity of ¹⁸F-FDG-PET (92.9%) and the excellent specificity of CMR (100%) for malignant diseases. For staging, ¹⁸F-FDG-PET outperformed CECT on per-patient (66.7% vs 55.6% correct diagnosis, respectively), per-organ (10 vs 7 organs, respectively), and per-lesion basis (> 29 vs > 25 lesions, respectively).

CONCLUSION

Combining ¹⁸F-FDG-PET with CMR improved the characterization of cardiac masses compared to each modality alone. Additionally, the diagnostic performance of ¹⁸F-FDG-PET was better than CECT for staging. This study suggests that the combination of CMR and ¹⁸F-FDG-PET is the most effective for the characterization of cardiac masses and the staging of these lesions.

Cardiac Imaging in Dialysis Patients

There is a well-established yet unexplained high prevalence of cardiovascular morbidity and mortality in individuals with end-stage kidney disease receiving dialysis. Potential causes include changes in cardiac structure and function, with increased left ventricular mass index as the best established cardiac structural change associated with this increase in mortality. However, in recent years, new echocardiographic and cardiac magnetic resonance imaging techniques have emerged that may provide novel markers that may better explain the mechanisms underlying the cardiovascular morbidity and mortality observed in end-stage kidney disease. This review outlines advances in cardiac imaging and the current status of imaging modalities, including echocardiography, cardiac magnetic resonance imaging, and cardiac positron emission tomography, to identify dialysis patients at high risk for cardiovascular mortality.

Imaging in Cardio-oncology: An Overview of an Emerging Medical Discipline

The world of cardio-oncology is an evolving field involving the assessment of cardiovascular disease in patients suffering from cancer. Cancer and cardiovascular diseases are the two leading causes of morbidity and mortality in the developed world. Globally, cancer is diagnosed in 12.7 million patients annually, and cancer incidence is projected to increase by 40% in high-income countries from 2008 to 2030. Chemotherapy is the main treatment for most cancers and improves survival, but is associated with significant cardiotoxicity. In recent years, the introduction of new biological anti-cancer treatments in addition to "classic" chemotherapy has further improved survival, but has also introduced new cardiovascular side effects beyond "pure" myocardial damage. The increasing number of patients with cancer and cancer survivors, and the growing complexity of cancer treatment and cardiovascular side effects, call for teamwork including cardiologists with specific training and expertise working in teams with oncologists, hematologists, and others. The purpose of this review was to describe the clinical background and importance of cardio-oncology, with an emphasis on the use of imaging in this clinical setting.

Strategies for targeting the cardiac sarcomere: avenues for novel drug discovery

Introduction: Heart failure remains one of the largest clinical challenges in the United States. Researchers have continually searched for more effective heart failure treatments that target the cardiac sarcomere but have found few successes despite numerous expensive cardiovascular clinical trials. Among many reasons, the high failure rate of cardiovascular clinical trials may be partly due to incomplete characterization of a drug candidate's complex interaction with cardiac physiology.Areas covered: In this review, the authors address the issue of preclinical cardiovascular studies of sarcomere-targeting heart failure therapies. The authors consider inherent tradeoffs made between mechanistic transparency and physiological fidelity for several relevant preclinical techniques at the atomic, molecular, heart muscle fiber, whole heart, and whole-organism levels. Thus, the authors suggest a comprehensive, bottom-up approach to preclinical cardiovascular studies that fosters scientific rigor and hypothesis-driven drug discovery.Expert opinion: In the authors' opinion, the implementation of hypothesis-driven drug discovery practices, such as the bottom-up approach to preclinical cardiovascular studies, will be imperative for the successful development of novel heart failure treatments. However, additional changes to clinical definitions of heart failure and current drug discovery culture must accompany the bottom-up approach to maximize the effectiveness of hypothesis-driven drug discovery.