Septic arthritis versus transient synovitis of the hip: gadolinium-enhanced MRI finding of decreased perfusion at the femoral epiphysis.
OBJECTIVE
The purpose of this study was to identify differences in the MRI findings of septic arthritis and transient synovitis in patients with nontraumatic acute hip pain and hip effusion.


METHODS
The MRI findings in nine patients with septic arthritis and 11 with transient synovitis were reviewed retrospectively. This study was approved by our institutional review board. The diagnoses were based on findings at physical examination, laboratory studies, and joint aspiration and bacteriologic study. The MRI findings were analyzed with emphasis on the grade of joint effusion, alterations in signal intensity in the soft tissues and bone marrow, and the presence of decreased perfusion at the femoral head.


RESULTS
Low signal intensity on fat-suppressed gadolinium-enhanced T1-weighted coronal MRI suggesting decreased perfusion at the femoral head of the affected hip joint was seen in eight of nine patients with septic arthritis and in two of 11 patients with transient synovitis. Statistically reliable differences (p = 0.005) were found between the two groups. Alterations in signal intensity in the bone marrow were seen in three patients with septic arthritis but in none of the patients with transient synovitis. Decreased perfusion on fat-suppressed gadolinium-enhanced coronal T1-weighted MRI was seen in the six patients with septic arthritis who did not have alterations in signal intensity involving the bone marrow.


CONCLUSIONS
Decreased perfusion at the femoral epiphysis on fat-suppressed gadolinium-enhanced coronal T1-weighted MRI is useful for differentiating septic arthritis from transient synovitis.
Kwack
Kyu-Sung
KS
Department of Radiology, Ajou University Medical Center, Wonchun Dong, Yongtong Gu, Suwon 442-721, Republic of Korea.
Cho
Jae Hyun
JH
Lee
Jei Hee
JH
Cho
Jae Ho
JH
Oh
Ki Keun
KK
Kim
Sun Yong
SY
D000293:Adolescent; D000328:Adult; D001170:Arthritis, Infectious / Q000175:diagnosis* / Q000473:pathology; D002648:Child; D002675:Child, Preschool; D003287:Contrast Media; D003937:Diagnosis, Differential; D004838:Epiphyses / Q000473:pathology; D005260:Female; D005270:Femur Head / Q000473:pathology; D019786:Gadolinium DTPA; D006621:Hip Joint / Q000473:pathology*; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D018709:Statistics, Nonparametric; D013585:Synovitis / Q000175:diagnosis* / Q000473:pathology
D003287:Contrast Media; D019786:Gadolinium DTPA