Skeletal muscle quantitative nuclear magnetic resonance imaging follow-up of adult Pompe patients

Adult late-onset Pompe disease is most often a slowly progressive limb-girdle and spine extensor muscle dystrophy, due to defective lysosomal acid maltase. With the exception of the few patients who present with a dramatically accelerated clinical course, standard diagnostic imaging fail to detect and evaluate disease progression between two successive visits. In muscle dystrophy of very rapid evolution, like the Duchenne disease, quantitative NMR imaging has successfully demonstrated its capacity to objectivate both disease activity and degenerative changes progression over short follow-up periods. The purpose of this retrospective monocentric open-label study was to investigate whether quantitative NMR imaging can monitor disease progression in adult Pompe patients despite its very slow nature. Quantitative imaging of Pompe patients succeeded in demonstrating that muscle fatty infiltration increased on average by 0.9 %/year, with the hamstring and adductor muscles showing the fastest degradation. Muscle water T2 mapping revealed that 32 % of all muscles had abnormally high T2 in at least one of two successive examinations. When muscle water T2 was abnormal, fatty degenerative changes were further increased by 0.61 %/year. Enzyme replacement therapy resulted in 0.68 %/year slowdown of the muscle fatty infiltration, in both muscles with normal and high T2s.