Cardiac receptor imaging

Molecular imaging has been focused in the field of cardiovascular medicine. With use of suitable radiopharmaceuticals, neuronal function in the cardiovascular system has been assessed in vivo. Of particular, positron emission tomography(PET) plays an important role for in vivo quantification of various neurotransmitter and receptor functions. We have recently developed 11C-labeled CGP12177, hydrophilic beta-adrenoreceptor antagonist, to measure myocardial beta-receptor density(Bmax) in vivo. The basic study showed high uptake in the lung and myocardium which was significantly suppressed by propranolol pretreatment in the rat model, suggesting specific binding of this ligand in the beta-receptors. Bmax was significantly reduced in patients with congestive heart failure. In addition, Bmax was inversely correlated with washout rate of 123I-MIBG from the myocardium in these patients. These new imaging technique has a potential role for assessing severity of heart failure and providing appropriate treatment strategy.     

Cardiac MR imaging of nonischemic cardiomyopathies

Cardiomyopathies, diseases of the myocardium associated with cardiac dysfunction, include hypertrophic, restrictive, and dilated forms and rare entities, such as arrhythmogenic right ventricular dysplasia, ventricular noncompaction, and apical ballooning syndrome. Many have similar presentations, but the underlying condition determines prognoses and treatment. Cardiac MR imaging plays a role in characterizing the range of entities and is crucial for evaluation and management. In addition, delayed enhanced imaging can allow differentiation among the forms of cardiomyopathy and offer prognostic information. As the speed and technical ease of cardiac imaging improve, MR imaging will assume an increasing role in the care of patients who have cardiomyopathy.     

Cardiac magnetic resonance imaging at 3.0 T

Cardiovascular magnetic resonance imaging (MRI) has gained widespread acceptance for the assessment of cardiovascular disease. Cardiac MRI requires fast data acquisition schemes because of constraints imposed by physiological motion of cardiac structures and blood flow, which dictate the suitable window of data acquisition. The ongoing improvement of MRI hardware and the development of tailored imaging techniques have been the cornerstones for rapid progress in cardiac MRI. Cardiac MRI at 3.0 T holds the promise to overcome some of the signal-to-noise (SNR) limitations, especially for techniques with borderline SNR at 1.5 T (eg, myocardial perfusion, assessment of viability, or imaging of coronary arteries). The improved SNR at 3.0 T can be used to increase the spatial resolution and/or reduce imaging time. It was shown that all applications of cardiac imaging at 1.5 T seem feasible also at 3.0 T and predominantly provide similar or improved image quality. Although specific absorption rate limitations and susceptibility effects remain a primary concern, the combination of high-field strength examinations with parallel imaging has increased the performance of techniques such as steady-state free-precession at 3.0 T. Therefore, the signal-to-noise and the contrast-to-noise ratios advantages at 3.0 T and the resulting potential benefit for an improved diagnostic value will constantly fuel further developments in this area and pave the way for novel, promising imaging techniques.     

Cardiac BMIPP imaging in acute myocardial infarction

Fatty acid metabolism functions as a major energy-producing system under aerobic conditions, but it is impaired immediately after myocardial ischaemia. This imaging can provide intracellular information which cannot be obtained by angiographical, perfusional or functional analysis. 123I-BMIPP and perfusion imagings in patients with acute myocardial infarction have demonstrated three different correlations between myocardial perfusion and fatty acid metabolism: concordant defects of perfusion and BMIPP which represent scar or non-viable tissue; lower BMIPP uptake relative to perfusion (perfusion–BMIPP mismatch) which implicates metabolically damaged, often dysynergic, but viable myocardium; and equivalently normal uptakes of perfusion and BMIPP in completely salvaged myocardium. Identification of these perfusion–metabolism correlations contributes to the detection of ischaemia-related myocardial injury in viable and non-viable myocardium, to the prediction of post-ischaemic or post-interventional functional recovery and to the identification of patients who have myocardium at ischaemic risk. Further clinical investigations might reveal more clearly the pathophysiological and prognostic implications of cardiac BMIPP imaging in patients with acute myocardial infarction.     

Cardiac arrest: long-term cognitive and imaging analysis

BACKGROUND: Neurological and cognitive sequelae resulting from cardiac arrest (CA), despite their potential personal and social impact, are usually not considered as major outcome measures in long-term analysis of survivors. The aim of this study is to analyze the contribution of neuropsychological testing and cerebral imaging to the development of a long-term classification of neurological impairment. PATIENTS AND METHODS: A total of 19 patients admitted over a 3 years period in an eight-bed intensive care unit of a tertiary care hospital with a diagnosis of CA were alive and attended a 6-month follow-up consultation. Eleven of these patients agreed to participate in this study carried out between 1 and 3 years after CA. Patients were classified using the Cerebral Performance Categories (CPC), neurological examination, detailed cognitive testing and computerized tomography (CT) scan with qualitative and quantitative imaging analysis. RESULTS: Six of the 11 patients had good cerebral performance. Verbal and visuo-spatial short-term memory scores were associated with CPC. All patients with at least moderate cerebral disability had abnormal verbal memory test results compared with only one survivor with CPC 1; visuo-spatial short-term memory was abnormal in four moderately affected survivors and normal in those with CPC 1. The bicaudate ratio evaluated in the CT scan was correlated with the verbal memory score while the III ventricle diameter correlated with the executive functions score, suggesting involvement of different brain areas in these functions. CONCLUSIONS: Neuropsychological and CT scan measurements are proxy measures of long-term impairment of CA survivors, providing a dichotomized global evaluation of CA survivors in close agreement with CPC.     

Cardiac imaging in patients with chronic liver disease

Cirrhotic cardiomyopathy (CCM) is characterized by an impaired contractile response to stress, diastolic dysfunction and the presence of electrophysiological abnormalities, and it may be diagnosed at rest in some patients or demasked by physiological or pharmacological stress. CCM seems to be involved in the development of hepatic nephropathy and is associated with an impaired survival. In the field of cardiac imaging, CCM is not yet a well‐characterized entity, hence various modalities of cardiac imaging have been applied. Stress testing with either physiologically or pharmacologically induced circulatory stress has been used to assess systolic dysfunction. Whereas echocardiography with tissue Doppler is by far the most preferred method to detect diastolic dysfunction with measurement of E/A‐ and E/E′‐ratio. In addition, echocardiography may also possess the potential to evaluate systolic dysfunction at rest by application of new myocardial strain techniques. Experience with other modalities such as cardiac magnetic resonance imaging and cardiac computed tomography is limited. Future studies exploring these imaging modalities are necessary to characterize and monitor the cardiac changes in cirrhotic patients.     

Cardiac myxoma: a contemporary multimodality imaging review

Cardiac myxoma (CM) is by far the most common primary benign cardiac tumor, typically arising in the left atrium with an attachment point in the fossa ovalis region. Although the etiology of CM remains unclear, we know that this endocardial-based mass originates from undifferentiated mesenchymal cells. Continuous technical improvements in the field of echocardiography since the 1960s has profoundly changed the diagnostic approach by allowing a good tumor detection as well as the preoperative planning by providing crucial information concerning the attachment point location. However, echocardiography has its limitations among which lack of tissue characterization and restricted field of view can arise diagnosis difficulties in atypical presentations. With the widespread and routine use of echocardiography and chest computed tomography (CT), incidental detection of CM is not infrequent. As a consequence, it has become mandatory for cardiologists and radiologists evolving in a multimodality imaging world to be familiar with the wide range of presentations of this tumor. The authors present here a review of the common and less common aspects of CM using the main imaging modalities available: echocardiography, cardiovascular magnetic resonance imaging, CT, positron emission tomography and coronary angiography.     

Cardiac magnetic resonance imaging in valvular heart disease

Cardiac magnetic resonance imaging (CMR) has rapidly gained acceptance as an accurate, reproducible and non‐invasive imaging method for assessment of a wide range of cardiovascular diseases. However, CMR has not been used widely for diagnostic purposes in valvular heart disease (VHD). Unlike echocardiography it has no body habitus‐related limitations and can thus be used to complement echocardiography. It is an especially good alternative for clinical follow‐up in patients with VHD, as it allows accurate measurement of valvular dysfunction and related ventricular burden. Additionally, CMR is an ideal method for evaluating complex congenital heart disease and determining the significance of its components. It can also be used to study the physiological course of valvular dysfunction and response to therapeutic interventions. In this review, we present a basic introduction to CMR methodology, including its advantages and potential problems, and the physiology and quantification in VHD. We also discuss clinical applications of CMR in VHD. Furthermore, we describe how a CMR study statement should be structured in order to increase clinical use of this valuable methodology in cardiology.     

Cardiac magnetic resonance imaging safety following percutaneous coronary intervention

In the first 8 weeks after percutaneous coronary intervention (PCI), possible negative interactions exist between the cardiac magnetic resonance (CMR) imaging environment and the weakly ferromagnetic material in coronary stents. There are circumstances when CMR would be indicated shortly following PCI, such as acute myocardial infarction (AMI). The purpose of this study is to demonstrate CMR safety shortly following stent PCI in AMI patients. We performed a retrospective analysis of safety data in AMI patients with recently placed coronary artery stents enrolled in a multi-center phase II trial for gadoversetamide. Patients underwent 1.5T CMR within 16 days of PCI. Vital signs (blood pressure, heart rate, respiratory rate, and body temperature) and ECGs were taken pre-CMR, 1, 2, and 24 h post-CMR. Any major adverse cardiac event (MACE) or other serious adverse events in the first 24 h after MRI were recorded. There were 258 stents in 211 AMI patients. The mean delay to CMR following PCI was 6.5 ± 4 days, with 62 patients (29 %) receiving CMR within 3 days and 132 patients (63 %) within 1 week. Patients showed no significant vital sign changes following CMR. Ten patients (4.7 %) showed mild, transient ECG changes. Within the 24-h follow-up group, 4 patients (1.9 %) had moderate to severe events, including chest pain (1) and elevated cardiac enzymes (1), resolving in 24 h; heart failure (1) and ischemic stroke (1). There were no deaths. This study demonstrates fewer MACE in AMI patients undergoing 1.5T CMR within 16 days of stent placement in comparison to post-stent event rate reported in the literature. This study adds to the CMR after stent PCI safety profile suggested by previous studies and is the largest and first study that uses multicenter data to assess stent safety following CMR examination.     

Cardiac myocardial perfusion imaging using dual source computed tomography

Purpose of this study was the evaluation of the thoracic aortic wall thickness as a potential identifier of patients at increased risk for future cardiac events. Thoracic aortic wall thickness was measured with MDCT in 160 patients. The CT-scans were implemented as non-invasive coronary angiography studies. Relationships between aortic wall thickness, sex, age, major risk factors and atherosclerotic plaque burden of the coronary arteries were explored. Higher values of maximum aortic wall thickness of the descending aorta (women P = 0.02, men P = 0.01) were found in patients with coronary atherosclerosis, compared to patients with same gender but excluded atherosclerosis. Aortic wall thickness of the mid-portion of the descending aorta of 3.0 mm is associated with coronary artery disease (CAD) with a specificity of 96.6% (sensitivity 27.5%) and a positive predictive value (PPV) of 93.3%. For patients with two or more major risk factors and a maximum wall thickness of equal or more than 2.6 mm we found a PPV of 100%. We conclude that measurements of maximum wall thickness of the descending aorta are a potential tool for detecting patients with coronary atherosclerosis. The potential effect of combining measurements of aortic wall thickness at routine chest CT studies with a possible cardiovascular screening is substantial and merits further study.