Evaluation of suspected musculoskeletal infection in children over 2 years of age using only fluid-sensitive sequences at MRI.

purposeThis study was conducted in order to evaluate whether an MRI protocol with only fluid-sensitive sequences can be used to evaluate for musculoskeletal (MSK) infection of the pelvis and limbs in children. MATERIALS AND

methodsThis retrospective study analyzed 90 contrast-enhanced (CE) MRI studies from 88 consecutive patients (52 boys and 36 girls; mean age 9 ± 4.3 years; range 2-17) that were performed for the clinical suspicion of MSK infection. Two radiologists reviewed each study twice. The initial study review included only the fluid-sensitive sequences (fluid-sensitive study); the second review, performed at least 1 month later, included all sequences of the contrast-enhanced study (CE study). At each review, anatomic sites of abnormal signal and overall suspicion for infection were recorded. Cohen's kappa and percent agreement were performed to compare agreement between readers, types of studies, and clinical diagnoses.

resultsInterreader agreement for both types of studies had kappa values between 0.86 and 1. For the assessment of MSK infection, the fluid-sensitive study had 100% sensitivity and 61.3% specificity, with 84.8% interreader agreement; and the CE study had 100% sensitivity and 71.0% specificity, with 88.6% interreader agreement. All cases of septic arthritis (13 cases) and osteomyelitis (25 cases) were identified as possible infection or infection until proven otherwise (negative predictive value 100%) with 100% interreader agreement on fluid-sensitive sequences.

conclusionAn abbreviated MRI study using only fluid-sensitive sequences has the same high degree of sensitivity as a CE study to identify MSK infection in children and could be used to exclude septic arthritis and osteomyelitis. KEY POINTS: • MRI with only fluid-sensitive sequences can be used to evaluate for musculoskeletal infection in children.