source: American Academy of Neurology
Ami Mankodi, W. Patricia Bandettini, William Kovacs, Alexander Hanna, Hirity Shimellis, Chioma Nnamdi-Emetarom, Lasya Gaur, Kenneth Fischbeck, Jianhua Yao, Andrew Arai
To simultaneously assess the magnetic resonance imaging (MRI) biomarkers of disease activity in the upper arm and chest wall skeletal muscles, diaphragm, and myocardium of patients with Duchenne muscular dystrophy (DMD).
There is a need for biomarkers to assess disease activity and treatment response in DMD. Outcome measures targeting the lower limb function may not be applicable to patients who lose their independent mobility during the duration of the trial. Cardiomyopathy and restrictive lung disease cause early morbidity and mortality in patients with DMD.
We analyzed quantitative maps of T1 and T2 relaxation times and muscle fat fraction (FF) measurements in the MRI of the upper arm skeletal muscles and heart in ambulatory boys with DMD and age matched healthy volunteer boys. The chest wall and diaphragm motion and right lung area were assessed during deep breathing in the cineBreathing MRI in both groups.
The upper arm skeletal muscle FF and T2 values were increased in DMD boys than healthy volunteers. Myocardial FF was similar between the groups. Myocardial T1 and T2 values were shortened in DMD participants than healthy volunteers. The chest wall movement was reduced in DMD boys, whereas the diaphragm movement was similar to healthy volunteers. Right lung area was reduced during maximum inspiration and expiration in DMD boys compared to healthy volunteers.
We detected fatty degeneration and edema in the upper arm skeletal muscles but not the myocardium in DMD boys who had normal ejection fraction. There was early involvement of the chest wall skeletal muscles but not diaphragm in DMD patients who had normal pulmonary function test. Imaging the heart and skeletal muscle using the same MRI methods may be useful in assessing relative disease status and therapeutic response in clinical trials of DMD.
National Institutes of Health, USA