Paraspinal Fat Stranding as an Unexpected Finding on Body Computed Tomography: A Key to Early Detection of Spinal Osteomyelitis

OBJECTIVE: At present, early detection of spinal osteomyelitis is a challenge. Patients may present with non-specific symptoms and diagnostic imaging studies may be obtained for seemingly unrelated complaints. Paraspinal fat stranding on body computed tomography (CT) as a sign of osteomyelitis is easily overlooked and has not been reported in the literature to our knowledge. The purpose of this study is to review findings on body CT that points to unsuspected spinal osteomyelitis. MATERIAL AND METHODS: A retrospective review of patients with spinal osteomyelitis who also had concomitant chest, abdominal, or pelvic CT scans between August 2013 and February 2017 yielded 10 patients who had confirmed osteomyelitis (ages between 51 and 75, mean age 64.8). Images and medical records were reviewed. RESULTS: The age of the patients ranged from 51 to 75 years (median value, 64). All patients had multiple underlying medical illnesses, and half of them had a known preceding infection such as sepsis or urinary tract infection. At presentation, three patients had a fever and two patients had neurologic deficits. Seven out of eight patients had elevated C-reactive protein and erythrocyte sedimentation rate, five patients had leukocytosis, and four patients had positive blood cultures. Paravertebral fat stranding and endplate erosions were observed in 9 and 6 cases, respectively, on initial body CT for unrelated indications, and subsequent magnetic resonance imaging confirmed osteomyelitis discitis. CONCLUSION: Clinically significant, but initially unsuspected, spinal pathology such as osteomyelitis may present on body CT scans. Earlier diagnosis of spinal osteomyelitis can be made by performing a focused evaluation of the paraspinal soft tissues and including osteomyelitis in the differential diagnosis, particularly in high-risk patients.