Clinical indications for repeat MRI in children with acute hematogenous osteomyelitis. 
At our center and at others, some children with acute hematogenous osteomyelitis (AHO) are evaluated with multiple magnetic resonance imagings (MRIs) during their treatment.  Do these serial MRI studies have a role in the management of AHO?  We examine several clinical indications for ordering a repeat MRI and whether the imaging study resulted in a change in management.  A total of 59 children (60 cases) with AHO were imaged with more than 1 MRI.  We retrospectively reviewed the MRI studies and hospital records to investigate whether the results of the MRIs prompted a change in clinical management (surgical exploration or drainage, biopsy, change in the course of antibiotics).  We investigated several clinical indicators including C-reactive protein (CRP) levels, time since index study, anatomic location of infection, and blood cultures.  Differences in the proportion of patients with specified clinical characteristics, whose repeat MRI resulted in a change in management, were assessed by the use of χ² analysis.  The median age of our patient population was 8.4 years; a total of 104 repeat MRI studies were undertaken on 59 children.  Eleven (10.6%) of these studies prompted a change in patient treatment.  Statistically significant indications for repeat MRI in changing clinical management included failure to improve clinically in 10 studies (21%, P<0.001), persistently elevated or increasing CRP levels in 11 MRI studies (52%, P<0.001), and the repeat study occurring within 14 days of the diagnostic MRI in 8 studies (29%, P=0.003).  The results of our study showed that additional MRI studies provide information that affected patient management in only a limited number of cases.  Although repeat MRI does not have a role in routine surveillance in children with AHO undergoing treatment, it can be a useful adjunct to clinical evaluation in patients who do not respond to therapy or who have a persistently elevated CRP level.  Level IV, Therapeutic Study.