MRI evaluation of multifidus muscles in adolescent idiopathic scoliosis.
BACKGROUND
The role of the multifidus muscles in the initiation and progression of curve in adolescent idiopathic scoliosis is not fully understood and controversy exists as to the side of the abnormality.


OBJECTIVE
To evaluate on MRI the multifidus muscles at the apex of the major curve in adolescent idiopathic scoliosis to ascertain if the multifidus muscles on the convex or concave side are abnormal and the relationship to curve severity.


METHODS
Forty-six patients with adolescent idiopathic scoliosis, separated into two groups, were studied using a 1.5-T MR scanner with the synergy spine coil, employing a modified STIR (short tau inversion recovery) axial sequence obtained at the apex of the major scoliotic curve.


RESULTS
No hyperintense signal change was demonstrated in the convex side multifidus muscles in any patient. In group I, 16 of 18 patients with severe or rapidly progressive curve showed increase in signal intensity in the multifidus muscle on the concave side of the apex of the curve. In group II, of the 15 patients with mild curve (Cobb angle 10-30 degrees), 4 had increased signal intensity in the multifidus muscle on the concave side; of the 13 with more severe curve (Cobb angle greater than 30 degrees), 10 had increase in multifidus signal intensity on the concave side.


CONCLUSIONS
The concave-side multifidus muscle at the apex of a scoliotic curve was morphologically abnormal. A significant association between abnormal signal change and curve severity was also established.
Chan
Y L
YL
Department of Diagnostic Radiology & Organ Imaging, Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong.
Cheng
J C
JC
Guo
X
X
King
A D
AD
Griffith
J F
JF
Metreweli
C
C
D000293:Adolescent; D000328:Adult; D002648:Child; D003430:Cross-Sectional Studies; D018450:Disease Progression; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D018482:Muscle, Skeletal / Q000473:pathology*; D011446:Prospective Studies; D015203:Reproducibility of Results; D012600:Scoliosis / Q000175:diagnosis*; D012720:Severity of Illness Index