Recent MR Techniques in Non-ischemic cardiomyopathy

Abstract

NonischemicCardiomyopathies are myocardial diseases associated withcardiac dysfunction. They are divided into primary and secondary cardiomyopathies .Management and prognosis frequently dependson the etiology of the cardiomyopathy involved. For the accurate diagnosisof theetiology of cardiomyopathy, the role of CMR is increasingly recognized and emphasized. There is no doubt that the gold standard method for etiological diagnosis is histological confirmation and the first-line imaging modality in patients under suspicion for myocardial disease is echocardiography. However, a comprehensive CMR protocol including cine, LGE, and other specific techniques can provide etiological diagnosis and prognostic implications. Cardiac MR is a valuable noninvasive imaging technique withits highspatial and temporal resolution, detailed three-dimensional (3D)images of cardiac and thoracic anatomy can be obtained. It is the goldstandard for quantification, accurate and reproducible assessmentof biventricular cardiac volumes and function, and can have profoundimplications regarding medical management.

Uniquely, it affordsthe opportunity for noninvasive tissue characterization thatreadily distinguishes edema, fat, thrombus, and fibrosis.Fibrotic remodeling can herald adverse out¬comes related to systolic and diastolic dysfunction, and arrhythmogenesis. Cardiac MRI provides a noninvasive modality for accurate and easy detection, localization and quantifi¬cation of myocardial fibrosis.Late-gadolinium enhancement imaging can be used to identify the presence, pattern, and size of replacement or focal fibrosis, and has proven independent prognostic capacity.

T1 mapping, a newer technique allows measuring the extracellular volume fraction (ECV) and accurate quantitation of diffuse and infiltrative interstitial fibrosis, and has tremendous prognostic potential in a wide variety of nonischemiccardiomyopathies . Mapping can noninvasively represent a “sample” of tissue from the entire myocardium and can supplement or potentially replace invasive myocardial biopsy. At a minimum, T1 mapping may help identify the most appropriate location for biopsy, if biopsy is deemed clinically necessary. Quan¬tifying the degree of fibrosis may guide treatment with regard to revascularization, device implanta¬tion, and medical therapy.