"MR corner sign": value for predicting presence of ankylosing spondylitis.
OBJECTIVE
The purpose of this study was to evaluate the MRI features of the "MR corner sign" and to determine its diagnostic usefulness in ankylosing spondylitis. We reviewed the spinal MR images of 52 patients with ankylosing spondylitis and compared these images with those of 52 age- and sex-matched control subjects.


CONCLUSIONS
The MR corner sign was defined as a triangular and sharply marginated corner abnormality in a vertebral body unassociated with osteophytes or Schmorl's node. MR corner lesions were significantly more common in the ankylosing spondylitis group than in the control group (Fisher's exact test, p < 0.001). The sensitivity, specificity, and positive and negative predictive values of the MR corner sign were 44%, 96%, 92%, and 63%, respectively. The most frequent feature of signal intensity was a Modic type II change (77%). In patients with ankylosing spondylitis, the MR corner sign was fre quently seen at the thoracolumbar junction, whereas degenerative corner lesions were commonly seen in the lower lumbar spine. When the MR corner sign is detected on spinal MR images in daily practice, it should not be overlooked because it suggests the possibility of ankylosing spondylitis, which should then be further evaluated.
Department of Radiology and Institute of Radiation Medicine, Seoul National University College of Medicine, 28, Yongon-dong, Chongno-gu, Seoul 110-744, Korea.
Na Ra
NR
Kim
Ja-Young
JY
Choi
Sung Hwan
SH
Hong
Woo Sun
WS
Jun
Joon Woo
JW
Lee
Jung-Ah
JA
Choi
Heung Sik
HS
Kang
D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013167:Spondylitis, Ankylosing / Q000473:pathology*