Acute hematogenous osteomyelitis of children: assessment of skeletal scintigraphy-based diagnosis in the era of MRI.

UNLABELLED The emergence of MRI has challenged the long-standing primacy of skeletal scintigraphy in pediatric cases of suspected acute hematogenous osteomyelitis (AHO) with nondiagnostic radiographs. This study evaluated a strategy in which skeletal scintigraphy is the primary and MRI a supplemental test. METHODS We reviewed the records of 213 children (age range, 8 mo-18 y; mean age, 67 mo) with musculoskeletal symptoms and nondiagnostic radiographs who were referred for skeletal scintigraphy because of the possibility of AHO. MRI was performed when diagnostic uncertainty persisted after skeletal scintigraphy or when abscess was suspected. RESULTS Diagnosis was made using skeletal scintigraphy without referral for MRI in 179 (84%) of the children, including 79 (92%) of 86 with a final diagnosis of AHO. In no instance was the diagnosis of AHO indicated only by MRI. Treatment and diagnosis were accomplished without referral for MRI in 146 (69%) of all cases and 46 (53%) of the AHO cases. Abscesses that required drainage were found in 3 (6%) of 48 cases of major-long-bone AHO. Each of these 3 had exhibited a slow therapeutic response before MRI. Drainable abscesses were found in 5 (20%) of 25 cases affecting the pelvis, which was the other preponderant location of AHO. These were found with pelvic foci both when MRI was performed at diagnosis and when MRI was performed during treatment. CONCLUSION An imaging strategy in which skeletal scintigraphy is the first test used when AHO is suspected but radiographs are negative remains highly effective. This approach can be most strongly advocated when symptoms are poorly localized or are localized to major long bones. MRI should be performed after skeletal scintigraphy shows major-long-bone AHO if treatment response is slow. Skeletal scintigraphy is also an appropriate first test for suspected radiographically occult pelvic AHO. Because of the association of abscesses with pelvic AHO, however, the use of MRI should be strongly considered after pelvic AHO is detected, and MRI might be substituted diagnostically for skeletal scintigraphy when symptoms are well localized to the pelvis.