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Magnetic resonance imaging of pyomyositis in 43 cases
R Soler1, E Rodríguez, C Aguilera
1Department of Radiology, Hospital Juan Canalejo, Xubias de Arriba, 84, 15006, La Coruña, Spain. r.soler@teleline.es
Purpose:
To describe the magnetic resonance imaging (MRI) findings in pyomyositis.
Methods And Materials:
Forty-three patients with proven muscle infection (30 males, 13 females) ranging in age from 14 to 86 years (mean 42 years) were studied with MRI. The initial clinical diagnose were soft tissue infection (n=27), neoplasm (n=12), thrombophlebitis (n=3), and lymphedema (n=1). Spin-echo T1- and T2-weighted images were obtained in all cases and STIR sequence in 6. Spin-echo T1-weighted images after Gd-DTPA injection were obtained in 16 cases. The signal intensity findings, the extent of the abnormalities in the soft tissue (muscle, fascial and subcutaneous involvement), the presence of fluid collections, and the involvement of neighbouring bone and joint were reviewed retrospectively.
Results:
A hyperintense signal on T2-weighted and STIR images were detected in all patients. Fluid collections were seen in 21 cases as localized areas of hypointensity on the T1-weighted images, and highly hyperintense areas on the T2-weighted images. In four patients a rim of high signal intensity was seen around the fluid collection on the T1-weighted images. On contrast-enhanced T1-weighted images there was diffuse enhancement in the patients without fluid collections that was heterogeneous in seven and homogeneous in two. After Gd-DTPA all fluid collections showed a central area without enhancement and a well-defined enhancing peripheral rim. Involvement of adjacent structures included subcutaneous tissue (n=25), bone marrow (n=14), fascial planes (n=15) and joints (n=11).
Conclusion:
MRI is useful in the assessment of pyomyositis and in determining the location and extension. A hyperintense rim on unenhanced T1-weighted images and peripheral enhancement after Gd-DTPA are useful for identifying the number, size, and location of soft-tissue abscesses.
Insights
Magnetic resonance imaging (MRI) effectively assesses pyomyositis, a muscle infection. MRI findings, including hyperintense rims and peripheral enhancement, help identify abscesses and determine the infection's extent.
Area of Science:
- Radiology
- Musculoskeletal Imaging
- Infectious Disease Imaging
Background:
- Pyomyositis is a primary bacterial infection of muscle, often presenting with non-specific symptoms.
- Accurate diagnosis and assessment of pyomyositis extent are crucial for effective management.
- Magnetic resonance imaging (MRI) offers detailed visualization of soft tissues, aiding in the diagnosis of musculoskeletal conditions.
Purpose of the Study:
- To characterize the magnetic resonance imaging (MRI) findings associated with pyomyositis.
- To evaluate MRI's utility in assessing the extent and identifying complications of muscle infections.
Main Methods:
- Retrospective review of MRI scans from 43 patients diagnosed with pyomyositis.
- Utilized spin-echo T1- and T2-weighted sequences, STIR sequences, and post-contrast Gd-DTPA enhanced T1-weighted images.
- Analyzed signal intensities, extent of soft tissue involvement (muscle, fascial, subcutaneous), fluid collections, and adjacent bone/joint involvement.
Main Results:
- All patients demonstrated hyperintense signals on T2-weighted and STIR images.
- Fluid collections (abscesses) were identified in 21 cases, appearing as hypointense on T1 and hyperintense on T2-weighted images.
- Contrast-enhanced MRI revealed diffuse enhancement in patients without abscesses and a characteristic peripheral enhancing rim around abscesses.
Conclusions:
- MRI is a valuable tool for diagnosing pyomyositis and delineating its anatomical extent.
- Specific MRI features, such as hyperintense rims on unenhanced T1 images and peripheral enhancement post-Gd-DTPA, are key indicators of soft-tissue abscesses.
- MRI aids in determining the number, size, and precise location of abscesses, guiding clinical management.