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Reproducibility of in-vivo diffusion tensor cardiovascular magnetic resonance in hypertrophic cardiomyopathy

Laura-Ann McGill12, Tevfik F Ismail1, Sonia Nielles-Vallespin123, Pedro Ferreira12, Andrew D Scott12, Michael Roughton1, Philip J Kilner12, S Yen Ho12, Karen P McCarthy12, Peter D Gatehouse1, Ranil de Silva12, Peter Speier4, Thorsten Feiweier4, Choukkri Mekkaoui5, David E Sosnovik5, Sanjay K Prasad12, David N Firmin12* and Dudley J Pennell12

Author Affiliations

1 Cardiovascular Magnetic Resonance Unit, Royal Brompton Hospital, Sydney Street, London SW3 6NP, United Kingdom

2 National Heart and Lung Institute, Imperial College, London, UK

3 National Heart Lung and Blood Institute (NHLBI), National Institutes of Health (NIH), DHHS, Bethesda, MD, USA

4 MR R&D, Siemens AG Medical Solutions, Erlangen, Germany

5 Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA

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Journal of Cardiovascular Magnetic Resonance 2012, 14:86  doi:10.1186/1532-429X-14-86

Published: 24 December 2012

Abstract

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). Global MD was significantly higher in the septum than the reference lateral wall (0.784 ± 0.188 vs 0.750 ± 0.154 x10-3 mm2/s, p < 0.001). 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.

Keywords:
Hypertrophic cardiomyopathy; Diffusion tensor imaging; Diffusion weighted imaging; Cardiovascular magnetic resonance; Disarray