In-vivo cardiac diffusion tensor imaging demonstrated good interstudy reproducibility in patients with hypertrophic cardiomyopathy, with a coefficient of variation of 7.2% for fractional anisotropy.
Observational (n=10)
Does in-vivo cardiac diffusion tensor imaging provide reproducible measurements of fractional anisotropy, mean diffusivity, and helix angle in patients with hypertrophic cardiomyopathy?
In-vivo cardiac diffusion tensor imaging provides reproducible measurements of myocardial architecture in hypertrophic cardiomyopathy, demonstrating potential clinical value for assessing myocardial disarray.
BACKGROUND: Myocardial disarray is an important histological feature of hypertrophic cardiomyopathy (HCM) which has been studied post-mortem, but its in-vivo prevalence and extent is unknown. Cardiac Diffusion Tensor Imaging (cDTI) provides information on mean intravoxel myocyte orientation and potentially myocardial disarray. Recent technical advances have improved in-vivo cDTI, and the aim of this study was to assess the interstudy reproducibility of quantitative in-vivo cDTI in patients with HCM. METHODS AND RESULTS: A stimulated-echo single-shot-EPI sequence with zonal excitation and parallel imaging was implemented. Ten patients with HCM were each scanned on 2 different days. For each scan 3 short axis mid-ventricular slices were acquired with cDTI at end systole. Fractional anisotropy (FA), mean diffusivity (MD), and helix angle (HA) maps were created using a cDTI post-processing platform developed in-house. The mean ± SD global FA was 0.613 ± 0.044, MD was 0.750 ± 0.154 × 10-3 mm2/s and HA was epicardium -34.3 ± 7.6°, mesocardium 3.5 ± 6.9° and endocardium 38.9 ± 8.1°. Comparison of initial and repeat studies showed global interstudy reproducibility for FA (SD = ± 0.045, Coefficient of Variation (CoV) = 7.2%), MD (SD = ± 0.135 × 10-3 mm2/s, CoV = 18.6%) and HA (epicardium SD = ± 4.8°; mesocardium SD = ± 3.4°; endocardium SD = ± 2.9°). Reproducibility of FA was superior to MD (p = 0.003). MD was significantly higher in the septum than the reference lateral wall (0.784 ±0.188 vs 0.714 ±0.155 ×10-3 mm2/s, p <0.001) corrected. Septal HA was significantly lower than the reference lateral wall in all 3 transmural layers (from -8.3° to -10.4°, all p < 0.001). CONCLUSIONS: To the best of our knowledge, this is the first study to assess the interstudy reproducibility of DTI in the human HCM heart in-vivo and the largest cDTI study in HCM to date. Our results show good reproducibility of FA, MD and HA which indicates that current technology yields robust in-vivo measurements that have potential clinical value. The interpretation of regional differences in the septum requires further investigation.
McGill et al. (Sun,) conducted a observational in Hypertrophic cardiomyopathy (n=10). Cardiac Diffusion Tensor Imaging (cDTI) vs. Repeat scan was evaluated on Interstudy reproducibility of fractional anisotropy (FA), mean diffusivity (MD), and helix angle (HA). In-vivo cardiac diffusion tensor imaging demonstrated good interstudy reproducibility in patients with hypertrophic cardiomyopathy, with a coefficient of variation of 7.2% for fractional anisotropy.
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