Myocardial strain imaging in Duchenne muscular dystrophy

Abstract

Cardiomyopathy (CM) is the leading cause of death for individuals with Duchenne muscular dystrophy (DMD). While DMD CM progresses rapidly and fatally for some in teenage years, others can live relatively symptom-free into their thirties or forties. Because CM progression is variable, there is a critical need for biomarkers to detect early onset and rapid progression. Despite recent advances in imaging and analysis, there are still no reliable methods to detect the onset or progression rate of DMD CM. Cardiac strain imaging is a promising technique that has proven valuable in DMD CM assessment, though much more work has been done in adult CM patients. In this review, we address the role of strain imaging in DMD, the mechanical and functional parameters used for clinical assessment, and discuss the gaps where emerging imaging techniques could help better characterize CM progression in DMD. Prominent among these emerging techniques are strain assessment from 3D imaging and development of deep learning algorithms for automated strain assessment. Improved techniques in tracking the progression of CM may help to bridge a crucial gap in optimizing clinical treatment for this devastating disease and pave the way for future research and innovation through the definition of robust imaging biomarkers and clinical trial endpoints.

Keywords: cardiac imaging; cardiac magnetic resonance; duchenne muscular dystrophy; echocardiography; pediatric cardiology; strain; strain imaging.

Figure 1

Example Cardiac Strain Imaging Techniques. 2D speckle tracking Transthoracic echocardiogram (TTE) image in the 4-chamber (A) and mid-ventricular short-axis (B)[adapted from Mele et al. (33)]. 3D speckle tracking TTE images in the 4-chamber (C) and short-axis (D)[adapted from Maffessanti et al. (34)]. Tissue Doppler imaging TTE images in the 2-chamber long-axis (E) and short axis (F) in a DMD patient. Velocity vector TTE images in the 4-chamber (G) and short axis (H) in a DMD patient. Cardiovascular magnetic resonance (CMR) strain method depicting myocardial tagging in the 4-chamber (I) and mid-ventricular short-axis (J) views in a DMD patient. CMR feature tracking example images in the 4-chamber (K) and short axis (L) views. Displacement Encoding with Stimulated Echoes (DENSE) example images in the 4-chamber (M) and short-axis (N) views [adapted from Cao et al. (35)]. Strain Encoded example images in the 4-chamber (O) and short-axis (P) view plane in a DMD patient. Multiple visualizations are available for each technique and the images presented here are only representative.