Although some studies have shown no significant difference in sensitivity and specificity in the diagnosis of osteomyelitis or septic arthritis with or without the use of gadolinium-based contrast agents, IV contrast has been shown to improve detection of abscesses [32,33]. Decreased femoral head enhancement on early postcontrast imaging has been noted as a reliable feature of septic arthritis not seen in transient synovitis, and diminished femoral head enhancement on MRI has been noted in the setting of septic arthritis in children under 12 months of age correlated with development of secondary osteomyelitis [34,35]. Contrast has been shown to markedly improve detection of infection of unossified growth cartilage (chondritis) in children <6 years of age, in which the cartilage most commonly appeared normal on unenhanced sequences; hypoenhancement was more commonly noted with infection [36,37]. In one study of children <18 months of age with community acquired S aureus infection of the unossified epiphyseal cartilage, 7 of 9 cases demonstrated normal cartilage signal on noncontrast sequences; hypoenhancement or nonenhancement of involved foci was used for diagnosis [36]. In another study of children <6 years of age, focal or global cartilage nonenhancement was demonstrated in 71% of 14 patients with surgically confirmed epiphyseal osteomyelitis, compared with 21% of controls [37]. Global enhancement defects were more sensitive, noted in 43% of cases but not seen in any control cases. Repeat MRI of the area of interest performed for worsening or persistent symptoms resulted in clinical management changes in 21% of patients [64]. In one study on septic elbow arthritis, 40% of patients did not respond to antibiotic therapy and were noted on subsequent elbow MRI to have concurrent osteomyelitis [60].
Osteomyelitis or Septic Arthritis Child Excluding Axial Skeleton PCAs. Although some studies have shown no significant difference in sensitivity and specificity in the diagnosis of osteomyelitis or septic arthritis with or without the use of gadolinium-based contrast agents, IV contrast has been shown to improve detection of abscesses [32,33]. Decreased femoral head enhancement on early postcontrast imaging has been noted as a reliable feature of septic arthritis not seen in transient synovitis, and diminished femoral head enhancement on MRI has been noted in the setting of septic arthritis in children under 12 months of age correlated with development of secondary osteomyelitis [34,35]. Contrast has been shown to markedly improve detection of infection of unossified growth cartilage (chondritis) in children <6 years of age, in which the cartilage most commonly appeared normal on unenhanced sequences; hypoenhancement was more commonly noted with infection [36,37]. In one study of children <18 months of age with community acquired S aureus infection of the unossified epiphyseal cartilage, 7 of 9 cases demonstrated normal cartilage signal on noncontrast sequences; hypoenhancement or nonenhancement of involved foci was used for diagnosis [36]. In another study of children <6 years of age, focal or global cartilage nonenhancement was demonstrated in 71% of 14 patients with surgically confirmed epiphyseal osteomyelitis, compared with 21% of controls [37]. Global enhancement defects were more sensitive, noted in 43% of cases but not seen in any control cases. Repeat MRI of the area of interest performed for worsening or persistent symptoms resulted in clinical management changes in 21% of patients [64]. In one study on septic elbow arthritis, 40% of patients did not respond to antibiotic therapy and were noted on subsequent elbow MRI to have concurrent osteomyelitis [60].