Community-Acquired Staphylococcal Musculoskeletal Infection in Infants and Young Children: Necessity of Contrast-Enhanced MRI for the Diagnosis of Growth Cartilage Involvement
Reference: Brown, L, Guillerman, R, Orth, R, Patel, J, Mason, E, Kaplan, S. Community-Acquired Staphylococcal Musculoskeletal Infection in Infants and Young Children: Necessity of Contrast-Enhanced MRI for the Diagnosis of Growth Cartilage Involvement. AJR 2012; 198: 194-199.
Scientific Literature Review
Reviewed by: Matthew H. Riordan, DPM
Residency Program: Cambridge Health Alliance, Cambridge, MA
Hematogenous and contiguous osteomyelitis in the pediatric population are seen in podiatric practices. This article highlights an important consideration for the appropriate choice of imaging modality in cases of suspected osteomyelitis in children with active growth centers.
A retrospective review of clinical charts and imaging studies in patients younger than 18 months of age with a diagnosis of community acquired S. aureus was conducted between 2001-2009. The inclusion criteria consisted of the age group above that had undergone an MRI with and without gadolinium contrast. Twenty-five patients were included in the study whose MRIs were reviewed by two staff musculoskeletal radiologists. The reviews of enhanced and unenhanced studies were performed separately to avoid bias. The recorded data included: the presence of skeletal involvement in unenhanced sequences, enhanced sequences, the location of the abnormality, the location and method of positive culture, and the presence of intra- and extraosseus fluid collections.
There were 34 sites of infection in the 25 patients with the femur being the most commonly affected (40 percent), followed by the tibia (26 percent), humerous (20 percent), radius and ulna (5 percent) and the tarsal bones (3 percent). The most commonly involved segment was the metaphysis or metadiaphysis. The sensitivity of the unenhanced MRI in these segments was 100 percent due to the lack of growth cartilage. In the areas involving growth cartilage, there were nine cases where both the unossified growth cartilage along with the adjacent metaphyseal bone were involved. Of these cases, four out of nine were detected with unenhanced sequences, and nine of nine were detected in the enhanced sequence. The affected cartilage in the enhanced sequence was shown as a focus of diminished enhancement. There were also nine cases where only the unossified growth cartilage was involved, of these cases the unenhanced sequences were positive in two of nine cases versus nine of nine in the enhanced sequences. These results were found to be statistically significant (p < 0.01).
The usefulness of gadolinium enhanced sequences in musculoskeletal infections has been challenged in recent literature. This study highlights the efficacy of the addition of gadolinium in the pediatric population with open epiphyseal growth plates and active primary growth centers. In this study, enhanced images of affected growth cartilage were found to have a sensitivity of 100 percent versus 40 percent in unenhanced images when the adjacent metaphyseal bone is involved and 20 percent with isolated growth center involvement. If there is a question of musculoskeletal infection in young children and infants, MRI with gadolinium contrast should be considered.