Objective: To evaluate the role of MRI in the early diagnosis and therapeutic assessment of pyomyositis.
Material and methods: We reviewed the cases of 11 patients with proven pyomyositis presenting from January 2002 to March 2006. We describe the characteristic findings at plain-film radiography, ultrasound, and MRI, as well as the clinical presentation and laboratory findings.
Results: The mean age of presentation was 10 years (range 3-14 years); there was a male predominance (7 cases). Only 4 patients had predisposing conditions. The most common clinical symptom was fever (9 cases). The most common laboratory findings were elevated erythrocyte sedimentation rate (10 cases) and leukocytosis (8 cases). Plain-film and US findings were nonspecific in all cases. Scintigraphy was positive in 4 cases. MRI showed osteomuscular involvement in all cases and enabled the abscesses to be identified.
Conclusions: Pyomyositis is a primary bacterial infection of skeletal muscle. In recent years pyomyositis has increasingly been diagnosed even in patients without predisposing factors. There is a male predominance. Imaging is essential for the diagnosis of the pyomyositis, and radiologists play a crucial role in the early diagnosis of this infection. MRI is the imaging method of choice for characterizing the infection.