Claudia Godi MD, Presenter: Nothing to Disclose

Alessandro Ambrosi, Abstract Co-Author: Nothing to Disclose

Corrado Santarosa, Abstract Co-Author: Nothing to Disclose

Sara Napolitano, Abstract Co-Author: Nothing to Disclose

Antonella Iadanza, Abstract Co-Author: Nothing to Disclose

Letterio Salvatore Politi MD, Abstract Co-Author: Nothing to Disclose

Francesca Nicastro, Abstract Co-Author: Nothing to Disclose

Marina Scarlato, Abstract Co-Author: Nothing to Disclose

Stefano Previtali, Abstract Co-Author: Nothing to Disclose

Fabio Ciceri, Abstract Co-Author: Nothing to Disclose

Giulio Cossu, Abstract Co-Author: Nothing to Disclose

Yvan Torrente, Abstract Co-Author: Nothing to Disclose

i) Quantitative and semiquantitative assessment of fat infiltration (FI) and muscle volume loss in lower limbs of children with Duchenne Muscular Dystrophy (DMD) by Magnetic Resonance Imaging (MRI); ii) computation of time-related quantitative curves of FI increase and MVI decay (Muscle Volume Index, a residual-to-total muscle volume ratio) in a cohort of DMD patients aged 6 to 14; iii) establishment of a morpho-functional relationship between MRI values and functional outcomes.

26 male children with DMD (baseline age: 6-12 years) were longitudinally assessed by lower limb 3T MRI and functional tests (Gowers, 10-meter time, North Star, 6-minute walking test). 5 age-matched controls were also examined. A total of 85 MRI studies were performed. FI, atrophy and hypertrophy were visually scored on hips, thighs and calves. T1 Signal Intensity Ratio (SIR) of muscle and nearby fat was used to quantify FI. Muscle volume was measured by applying thresholds on T1-weighted images, and results were normalized for the whole muscle volume to obtain a MVI. Permutation and regression analyses according to both age and functional tests were calculated. P-values <0.05 were considered significant.

FI was present on glutei and adductor magnus in all patients since the age of 6, with a proximal-to-distal progression in the lower limb and selective sparing of sartorius and gracilis. Atrophy was almost parallel to the FI pattern, whereas hypertrophy was observed in sartorius, gracilis and calf muscles. SIRs and MVIs were significantly different from the control values, except for SIRs of sartorius and gracilis. Age-related curves with percentile values were calculated for SIRs and MVIs, to provide a reference background for future experimental therapy trials. SIRs and MVIs significantly correlated with all clinical measures, and could reliably predict functional outcomes in a linear or exponential fashion.

SIRs and MVIs are objective predictors of functional outcomes, which can improve the staging of DMD patients. MRI-based curves display the multistep muscle involvement over time and can provide reference values of FI and muscle volume loss for both clinical and research settings.

MR-based indexes of fat infiltration and muscle volume can track the progression of DMD in lower limbs, providing background reference data for patients potentially involved in future therapy trials

Godi, C, Ambrosi, A, Santarosa, C, Napolitano, S, Iadanza, A, Politi, L, Nicastro, F, Scarlato, M, Previtali, S, Ciceri, F, Cossu, G, Torrente, Y, Reference Values of Fat Infiltration and Muscle Volume Loss for Morpho-functional Predictive Behaviour in Duchenne Muscular Dystrophy: A Longitudinal MRI Study.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14015213.html