Cardiac computed tomography (CT) is increasingly used in the evaluation of cardiomyopathies, particularly in patients who are not able to undergo other non-invasive imaging tests such as magnetic resonance imaging (MRI) due to the presence of MRI-incompatible pacemakers/defibrillators or other contraindications or due to extensive artifacts from indwelling metallic devices. Advances in scanner technology enable acquisition of CT images with high spatial resolution, good temporal resolution, wide field of view and multi-planar reconstruction capabilities. CT is useful in cardiomyopathies in several ways, particularly in the evaluation of coronary arteries, characterization of cardiomyopathy phenotype, quantification of cardiac volumes and function, treatment-planning, and post-treatment evaluation. In this article, we review the imaging techniques and specific applications of CT in the evaluation of cardiomyopathies.

/pdf/computed-tomography-of-cardiomyopathies-2fbe9kleww.pdf

Computed tomography of cardiomyopathies.

Nonischemic myocardial disease or cardiomyopathy can present as arrhythmia, palpitations, heart failure, dyspnea, lower extremity edema, ascites, syncope, and/or chest discomfort and can be classified as either systolic, diastolic, or a combination of both. Echocardiography is the mainstay of evaluating left ventricular function. However, cardiac magnetic resonance imaging (MRI) is now considered the reference standard imaging technique to assess myocardial anatomy, function, and viability. Advanced MRI techniques with delayed myocardial enhancement, especially, can provide information beyond echocardiography for tissue characterization in CM and can assist in determining specific etiology or in narrowing the differential. Often imaging enhancement patterns, signal characteristics, and morphology on MRI can lead to specific diagnoses such as amyloidosis, hypertrophic CM, or iron deposition. Cardiac computed tomography is usually used in excluding coronary artery disease but can also be used in some patients unable to undergo cardiac MRI to assess arrhythmogenic right ventricular dysplasia. Both 18-F-fluoro-2-deoxyglucose positron emission tomography and delayed contrast-enhanced MRI can be used to assess for cardiac sarcoidosis. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 3 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

ACR appropriateness criteria® nonischemic myocardial disease with clinical manifestations (ischemic cardiomyopathy already excluded).

Nonischemic cardiomyopathies encompass a broad spectrum of myocardial disorders with mechanical or electrical dysfunction without evidence of ischemia. There are five broad variants of nonischemic cardiomyopathies; hypertrophic cardiomyopathy (Variant 1), restrictive or infiltrative cardiomyopathy (Variant 2), dilated or unclassified cardiomyopathy (Variant 3), arrhythmogenic cardiomyopathy (Variant 4), and inflammatory cardiomyopathy (Variant 5). For variants 1, 3, and 4, resting transthoracic echocardiography, MRI heart function and morphology without and with contrast, and MRI heart function and morphology without contrast are the usually appropriate imaging modalities. For variants 2 and 5, resting transthoracic echocardiography and MRI heart function and morphology without and with contrast are the usually appropriate imaging modalities. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

ACR Appropriateness Criteria® Nonischemic Myocardial Disease with Clinical Manifestations (Ischemic Cardiomyopathy Already Excluded).

Background and Objectives: Digital heart atlases play important roles in computational cardiac simulation and medical image analysis. During the past decades, various heart anatomy models were developed, but they mostly focused on the ventricular part. Recently, a number of whole-heart atlases were developed but they rarely modelled the motion features. This study constructed a whole-heart atlas incorporating dynamic cardiac motion. Materials and Methods: The shape and motion features of the atlas were learnt from a training set of 57 dynamic computed tomographic angiography images including 20 cardiac phases. Inter-subject variations of the heart anatomy and motion were incorporated into the atlas using the statistical shape modelling approach. Clinically relevant physiological parameters (e.g., chamber volumes, ejection fraction, and percentage of systolic phase) were correlated with the shape and motion variations using the linear regression approach. The shape and motion pattern of the atlas can be adapted by adjusting the physiological parameters. Results: Quantitative experiments were conducted to measure the anatomical accuracy of the atlas for whole-heart shape reconstruction of different subjects, a mean Dice score of 0.89–0.93 and a mean surface distance of 1.02–1.91 mm were achieved for the four heart chambers, respectively. Conclusions: This atlas provides a novel computational tool with adjustable shape and motion parameters for cardiac simulation research. 

A dynamic statistical cardiac atlas with adjustable shape and motion features

Stress-induced cardiomyopathy, known as Takotsubo, is an increasingly recognized syndrome, characterized by transient apical or midventricular dysfunction, which mimics myocardial infarction in the absence of significant coronary artery disease, and is thought to be due to transient catecholamine overload. Multidetector computed tomography (MDCT) is a novel imaging approach increasingly recognized as a rapid, noninvasive diagnostic modality to assess coronary anatomy and cardiac function. Few reports have been published regarding its utility in the assessment of myocardial viability after myocardial infarction. We describe 2 patients with Takotsubo cardiomyopathy who underwent MDCT imaging. To our knowledge, this is the first report describing the utility of MDCT that shows the absence of delayed hyperenhancement in patients with Takotsubo cardiomyopathy.

Viability assessment by multidetector computed tomography in Takotsubo cardiomyopathy.

Stress-induced cardiomyopathy, also known as Broken Heart Syndrome or Takotsubo cardiomyopathy, is an increasingly recognized syndrome characterized by transient apical or midventricular dysfunction that mimics myocardial infarction in the absence of significant coronary artery disease. This disorder is much more common in women compared with men, with a mean age of 62–75 years. Different morphologic patterns of left ventricular dysfunction have been observed, with apical ballooning and hypercontracting basal segments being the most common and are observed in 60% of patients. The exact mechanism of this disorder is not well understood. Catecholamines may play an important role in the genesis of this disorder, as illustrated by a small case series demonstrating significantly increased plasma epinephrine and norepinephrine. Patients with stress-induced cardiomyopathy also tend to be prone to coronary vasospasm, induced by excess catecholamines. Typically, ionotropic agents are avoided in apical ballooning d...

/pdf/hemodynamics-of-cardiogenic-shock-in-a-broken-heart-syndrome-34kturkxvw.pdf

Zahid Virk

Papers

Viability assessment by multidetector computed tomography in Takotsubo cardiomyopathy.

Hemodynamics of cardiogenic shock in a Broken Heart Syndrome patient: paradoxical effect of ionotropic agents in apical ballooning