Left ventricular T2 distribution in Duchenne Muscular Dystrophy
Although previous studies have helped define the natural history of Duchenne Muscular Dystrophy (DMD)-associated cardiomyopathy, the myocardial pathobiology associated with functional impairment in DMD is not yet known.The objective of this study was to assess the distribution of transverse relaxation time (T2) in the left ventricle (LV) of DMD patients, and to determine the association of myocardial T2 heterogeneity to the severity of cardiac dysfunction. DMD patients (n=26) and normal control subjects (n=13) were studied by Cardiovascular Magnetic Resonance (CMR).
DMD subject data was stratified based on subject age and LV Ejection Fraction (EF) into the following groups: A (<12 years old, n=12); B ([greater than or equal to]12 years old, EF >55%, n=8) and C ([greater than or equal to]12 years old, EF [less than or equal to] 55%, n=6). Controls were also stratified by age into Groups N1 (<12 years, n=6) and N2 (>12 years, n=5).
LV mid-slice circumferential myocardial strain (epsiloncc) was calculated using tagged CMR imaging. T2 maps of the LV were generated for all subjects using a black blood dual spin echo method at two echo times.
The Full Width at Half Maximum (FWHM) was calculated from a histogram of LV T2 distribution constructed for each subject.
Results: In DMD subject groups, FWHM of the T2 histogram rose progressively with age and decreasing EF (Group A FWHM= 25.3+/-3.8 ms; Group B FWHM= 30.9+/-5.3 ms; Group C FWHM= 33.0+/-6.4ms). Further, FWHM was significantly higher in those with reduced circumferential strain (|epsiloncc|[less than or equal to]12%) (Group B, and C) than those with |epsiloncc|>12% (Group A).
Group A FWHM was not different from the two normal groups (N1 FWHM = 25.3+/-3.5 ms; N2 FWHM= 24.0+/-7.3ms).
Conclusion: Reduced EF and epsiloncc correlates well with increased T2 heterogeneity quantified by FWHM, indicating that subclinical functional impairments could be associated with pre-existing abnormalities in tissue structure in young DMD patients.
Author: Janaka WansapuraKan HorWojciech MazurRobert FleckSean HagenbuchD Woodrow BensonWilliam Gottliebson
Credits/Source: Journal of Cardiovascular Magnetic Resonance 2010, 12:14
Published on: 2010-03-18
Copyright by the authors listed above - made available via BioMedCentral (Open Access). Please
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