Computed and magnetic resonance imaging for osteomyelitis in children

Introduction. The frequency of osteomyelitis in pediatric population is approximately 1:5000, and the mortality rate is from 0.2% to 17.0%. In children, acute bone infection is most often of hematogenous origin. Transition from the classical radiography and radionuclide examination to computed tomography (CT) and magnetic resonance imaging (MRI) has been completed.

Purpose. To demonstrate potentials of CT and MRI in the diagnostics of osteomyelitis in children.

Material and methods. 238 children with osteomyelitis, aged 1-17 years (average 9.1 ± 4.9 years), were examined for the last ten years. There were 126 boys (53%) and 112 girls (47%). Depending on the disease nosology, patients were divided as follows: hematogenous osteomyelitis (n = 112 children, 47%), BCG-osteomyelitis (n = 20, 8.4%), post-traumatic osteomyelitis (n = 67, 28.2%). 138 children (58%) were treated surgically. CT scanning was performed in 174 patients using Brilliance 16 scanners. MRI was performed using Philips AchievadStream 3.0 T scanner to obtain multi-planar STIR, T1-, T2- and PD weighted images (SE and GE). In addition, new MRI methods were used: diffusion-weighted images (DWI), Dixon, dynamic MRI with contrast enhancement (DCE).

Results. CT examination, which was performed in 174 patients at the same terms as radiography, confirmed density decrease ( though not large). Periosteal changes were better visualized at CT examination in 107 out of 174 patients (61.5%) including those who had changes at the classical radiography. MRI was performed in 51 patients ( including those with intravenous contrast enchancement) on Day 2-3 since the disease onset. This examination was effective in all cases (sensitivity 100%). T2WI and STIR with fat suppression (FS) clearly revealed edema of the bone marrow and surrounding muscles as well as small changes.

Conclusion. MRI is the most informative diagnostic technique in acute osteomyelitis at its early period because main signs of the initial stage of this disease - edema of bone marrow, periosteum and soft tissues - are detected during the first days. In addition, MRI reveals details of bone and soft tissues damages, including abscess and sequester formation, especially in spinal and pelvic lesions. MRI sensitivity in osteomyelitis reaches up to 100%. Sequences with the fat suppression (FS) can better detect bone marrow edema and inflammation than radiography. MRI is a preferable technique in diagnostics of infectious lesions of the spine, pelvis, and limbs.