Utility of late gadolinium enhancement in Duchenne muscular dystrophy (RF_TH_202)

Late gadolinium enhancement (LGE) using cardiovascular magnetic resonance imaging (CMR) indicates myocyte death and replacement by fibrofatty tissue. Early onset of cardiac myocardial fibrosis as indicated by LGE on CMR is associated with earlier progression of cardiomyopathic changes including LV systolic dysfunction. Dilated cardiomyopathy is the inevitable complication and common cause of death in Duchenne muscular dystrophy (DMD) - presumably secondary to myocardial fibrosis. Detecting the earliest changes of this disease may help us understand the impact of treatments.

Methods: All children with DMD imaged in a single tertiary Centre between January 2021 and May 2024 were identified from our institutional database. Demographic data and retrospective data of all CMR parameters including ventricular volumes and ejection fraction were collected along with echocardiographic ejection fraction. Presence of LGE was independently assessed by two experienced cardiac imagers using three post gadolinium sequences: 3-dimensional, inversion recovery, fast low angle shot sequence (3D IR FLASH), standard single shot inversion recovery sequence (standard LGE) and T1 scout (Look-Locker) sequence. The quality of each sequence was also independently graded. A small proportion of cases (12/60) with discordant LGE findings were jointly re-assessed later by both reviewers to provide a final interpretation.


Results:

We included 60 patients (age 15±3 years, 100% male) in the final analysis after excluding 2 patients who did not tolerate the CMR and had incomplete imaging. 35/60 (58%) patients were decisively ‘positive for LGE’ after final interpretation, 4 (7%) remained ‘suspicious for LGE’ even after a second ‘joint’ review while 1 study was interpreted as ‘non-diagnostic’ on all three sequences. The predominant site of LGE was subepicardial and the most common segment was the basal inferolateral wall. 7 (19%) of 35 LGE-positive patients showed normal biventricular volumes and function on CMR while 22/35 (68%) had normal function on ECHO. 
Standard LGE and TI scout were performed in all patients while 3D IR FLASH was not performed in 3/60 (8%). 3D IR FLASH showed poor image quality in 17/60 (28%) patients but, when acquired properly, showed LGE more convincingly when compared to the other two sequences. Standard LGE was least susceptible to image degradation with only 2/60 (3%) showing poor image quality. TI scout was more useful as a problem-solving tool when findings were doubtful in the other two sequences. Kappa analysis showed substantial to almost perfect interobserver agreement on the study quality and image interpretation. 



Conclusion: A significant proportion of childhood DMD patients have myocyte death. Cardiomyopathic changes occur before ECHO-based functional deterioration suggesting that LGE is an important prognostic indicator. Baseline CMR with contrast is recommended for all DMD patients as soon as they can tolerate the scan.