Twenty-one patients were diagnosed with PM in our institution from September 2006 to August 2012.
Two patients were excluded,
one who had not received MDCT and one without PM criteria.
Remaining nineteen patients had PM criteria; clinical data of 19 patients and contrast-enhanced-MDCT images were retrospectively analyzed.
The 19 patients were comprised of 14 male patients and 5 female patients with ages from 42 to 85 years (mean,
69.8 years) (See Table 1,
microbiology and laboratory data for each patient were collected to analyze (See Table 2 ).
MDCT scans were obtained using a 16-slice CT scanner and in all patients were performed with use of iodinated contrast material.
Pyomyositis was classified in three stages,
(1) invasive stage which causes the muscle to become edematous and painful,
(2) suppurative phase is characterized by formation of an abscess.
(3) The last stage involves systemic spread of the infection,
leading to septicemia,
multifocal or extensive abscesses,
In stage 1 ( Fig. 3),
subcutaneous changes; enlargement,
decreased attenuation and extension of the affected muscles were reviewed.
Fig. 3: Case 2. Pyomyositis of bilateral paraspinal and both thighs at its invasive or early stage (no abscess formation. Contrast-enhanced coronal CT.
In stages 2 (Fig. 15 ) and 3 (Fig. 11,
Fig. 12 ),
the size of the abscesses was quantified by measuring the maximal diameters in three dimensions.
The extension of the abscesses was also analyzed according to the involvement of more than one muscle bundle,
joints or bone.
Fig. 15: Case 9. Pyomyositis of right iliopsoas at its suppurative phase, with abscess formation. Cultured microorganism Staphylococcus epidermidis. Contrast-enhanced axial CT.
Fig. 11: Case 5. Pyomyositis of right thigh at its suppurative phase, multifocal abscess formation and involvement of right knee. Cultured microorganism Staphylococcus aureus. Contrast-enhanced axial CT.
Fig. 12: Case 5. Pyomyositis of right thigh at its suppurative phase, multifocal abscess formation and involvement of right knee. Cultured microorganism Staphylococcus aureus. Contrast-enhanced coronal CT.
Sixteen received surgical intervention or image-guided drainage/aspiration (Fig. 8 ) of the abscess along with administration of antibiotics,
while remaining three were promptly treated solely with antibiotics.
Fig. 8: Case 3. Pyomyositis of bilateral iliopsoas at its suppurative phase and multifocal abscess formation. Drainage on the left side. Cultured microorganism Bacteroides distasonis Contrast-enhanced coronal CT.