[1] Univ London Imperial Coll Sci Technol & Med, Hammersmith Hosp, MRC, Clin Sci Ctr,Muscle Cell Biol Grp, London W12 0NN, England
[2] Univ London Imperial Coll Sci Technol & Med, Hammersmith Hosp, Imaging Sci Dept, London W12 0NN, England
[3] Shanxi Med Univ, Hosp 2, Imaging Sci Dept, Taiyuan, Peoples R China
[4] Bristol Royal Infirm & Gen Hosp, Dept Med Phys & Bioengn, Bristol BS2 8HW, Avon, England
[5] Peoples Liberat Army Gen Hosp, Dept Ultrasound, Beijing, Peoples R China
[6] Carolinas Med Ctr, Neuromuscular ALS Ctr, Charlotte, NC 28203 USA