Magnetic resonance imaging of muscle in amyotrophic lateral sclerosis.
OBJECTIVE
To characterize leg muscle abnormalities in patients with ALS using MRI, and to correlate MRI with standard neurologic measures of motor neuron dysfunction.


METHODS
Eleven ALS patients were studied twice (once at baseline and again after 4 months) and compared with eight normal control subjects. MRI data of the lower extremities were compared with tibialis anterior compound muscle action potential amplitude (CMAPa) and foot dorsiflexion maximal voluntary isometric contraction (MVIC).


RESULTS
Muscle MRI was abnormal by visual inspection in six of 11 patients. The mean muscle T1 time and muscle volume were not different in patients compared with normal control subjects (p > 0.1). However, the mean T2 times were increased in the patients compared with normal control subjects (p = 0.009). T1 times did not correlate with CMAPa or MVIC. Muscle volume correlated with MVIC (r = 0.73 to 0.78, p < 0.02) but not with CMAPa (p > 0.05). There was a strong negative correlation (r < -0.8, p < or = 0.01) between muscle T2 time and MVIC and CMAPa. Also, the change in T2 relaxation time correlated with the change in CMAPa as the disease progressed (r = -0.63, p = 0.037).


CONCLUSIONS
Of the MRI characteristics studied, T2 relaxation time was the best indicator of motor neuron dysfunction and may have a role in objective evaluation of motor neuron dysfunction.
Department of Neurology, The University of Texas Southwestern Medical Center at Dallas, 75235-8897, USA.
W W
WW
Bryan
J S
JS
Reisch
G
G
McDonald
L L
LL
Herbelin
R J
RJ
Barohn
J L
JL
Fleckenstein
D000200:Action Potentials / Q000502:physiology; D000328:Adult; D000690:Amyotrophic Lateral Sclerosis / Q000175:diagnosis* / Q000503:physiopathology*; D003711:Demyelinating Diseases / Q000473:pathology / Q000503:physiopathology; D005260:Female; D005528:Foot / Q000502:physiology; D006801:Humans; D007537:Isometric Contraction; D008279:Magnetic Resonance Imaging; D008297:Male; D008648:Mesoderm / Q000473:pathology; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000294:innervation / Q000473:pathology / Q000503:physiopathology*; D009431:Neural Conduction / Q000502:physiology; D011237:Predictive Value of Tests