Longitudinal MRI quantification of muscle degeneration in Duchenne muscular dystrophy.
The aim of this study was to evaluate the usefulness of magnetic resonance imaging (MRI) in detecting the progression of Duchenne muscular dystrophy (DMD) by quantification of fat infiltration (FI) and muscle volume index (MVI, a residual-to-total muscle volume ratio).



Twenty-six patients (baseline age: 5-12 years) with genetically proven DMD were longitudinally analyzed with lower limb 3T MRI, force measurements, and functional tests (Gowers, 10-m time, North Star Ambulatory Assessment, 6-min walking test). Five age-matched controls were also examined, with a total of 85 MRI studies. Semiquantitative (scores) and quantitative MRI (qMRI) analyses (signal intensity ratio - SIR, lower limb MVI, and individual muscle MVI) were carried out. Permutation and regression analyses according to both age and functional test-outcomes were calculated. Age-related quantitative reference curves of SIRs and MVIs were generated.



FI was present on glutei and adductor magnus in all patients since the age of 5, with a proximal-to-distal progression and selective sparing of sartorius and gracilis. Patients' qMRI measures were significantly different from controls' and among age classes. qMRI were more sensitive than force measurements and functional tests in assessing disease progression, allowing quantification also after loss of ambulation. 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 and loss of ambulation.



qMRI-based indexes are sensitive measures that can track the progression of DMD and represent a valuable tool for follow-up and clinical studies.
Neuroradiology Department Neuroradiology Research Group and CERMAC San Raffaele Scientific Institute and Vita-Salute San Raffaele University Milan Italy.
Claudia
0000-0003-1330-1673
C
Godi
CUSSB University Centre for Biomedical Sciences Vita-Salute San Raffaele University Milan Italy.
Alessandro
0000-0003-1976-5663
A
Ambrosi
Laboratory of Analysis and Rehabilitation of Motor Function Division of Neuroscience San Raffaele Scientific Institute Milan Italy.
Francesca
F
Nicastro
Division of Neuroscience Institute of Experimental Neurology (INSpe) San Raffaele Scientific Institute Milan Italy.
Stefano C
SC
Previtali
Neuroradiology Department Neuroradiology Research Group and CERMAC San Raffaele Scientific Institute and Vita-Salute San Raffaele University Milan Italy.
Corrado
C
Santarosa
San Raffaele Telethon Institute for Gene Therapy (HSR-TIGET) and Pediatric Immunohematology and Bone Marrow Transplantation Unit San Raffaele Scientific Institute Milan Italy.
Sara
S
Napolitano
Neuroradiology Department Neuroradiology Research Group and CERMAC San Raffaele Scientific Institute and Vita-Salute San Raffaele University Milan Italy.
Antonella
A
Iadanza
Division of Neuroscience Institute of Experimental Neurology (INSpe) San Raffaele Scientific Institute Milan Italy.
Marina
M
Scarlato
Division of Neuroscience Institute of Experimental Neurology (INSpe) San Raffaele Scientific Institute Milan Italy.
Maria Grazia
MG
Natali Sora
Laboratory of Analysis and Rehabilitation of Motor Function Division of Neuroscience San Raffaele Scientific Institute Milan Italy.
Andrea
A
Tettamanti
Neuroradiology Department Neuroradiology Research Group and CERMAC San Raffaele Scientific Institute and Vita-Salute San Raffaele University Milan Italy.
Simonetta
S
Gerevini
San Raffaele Telethon Institute for Gene Therapy (HSR-TIGET) and Pediatric Immunohematology and Bone Marrow Transplantation Unit San Raffaele Scientific Institute Milan Italy.
Maria Pia
MP
Cicalese
Stem Cell Laboratory Department of Pathophysiology and Transplantation Universitá degli Studi di Milano Fondazione IRCCS Cá Granda Ospedale Maggiore Policlinico Centro Dino Ferrari, Milan Italy.
Clementina
C
Sitzia
Radiology Department San Raffaele Scientific Institute and Vita-Salute San Raffaele University Milan Italy.
Massimo
M
Venturini
Neuroradiology Department Neuroradiology Research Group and CERMAC San Raffaele Scientific Institute and Vita-Salute San Raffaele University Milan Italy.
Andrea
A
Falini
Laboratory of Analysis and Rehabilitation of Motor Function Division of Neuroscience San Raffaele Scientific Institute Milan Italy.
Roberto
R
Gatti
Hematology and BMT Unit San Raffaele Scientific Institute and Vita-Salute San Raffaele University Milan Italy.
Fabio
F
Ciceri
Institute of Inflammation and Repair University of Manchester Manchester United Kingdom.
Giulio
G
Cossu
Stem Cell Laboratory Department of Pathophysiology and Transplantation Universitá degli Studi di Milano Fondazione IRCCS Cá Granda Ospedale Maggiore Policlinico Centro Dino Ferrari, Milan Italy.
Yvan
Y
Torrente
Neuroradiology Department Neuroradiology Research Group and CERMAC San Raffaele Scientific Institute and Vita-Salute San Raffaele University Milan Italy; Neuroimaging Research Division of Hematology/Oncology Boston Children's Hospital Boston MA USA; Department of Pediatrics Harvard Medical School Boston MA USA; University of Massachusetts Memorial Medical Center and University of Massachusetts Medical School Worcester MA USA.
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