[Application of the ubiquicidin 29-41 scan in the diagnosis of pyogenic vertebral osteomyelitis].

Background: The non-invasive diagnosis of vertebral osteomyelitis is a difficult one. Studies confirm MRI as the gold standard with 92% sensitivity and 94% specificity. Scintigraphy combined with Tc99-Ga67 used to be the procedure of choice before the advent of PET with labeled glucose, which has a high sensitivity and specificity, but cannot distinguish a focus of infection from inflammation. Scintigraphy with UBI29-41 is an infection-specific study that was recently described in the literature. There are no studies showing its value in the diagnosis of vertebral osteomyelitis.
Objective: The purpose of the study is to show that the Tc99-UBI29-41 scan has 99% sensitivity for vertebral osteomyelitis.
Methods: This is a study of a diagnostic test. The case series was composed of the records of UBI scans performed at the Nuclear Medicine Department, HcHMAE. The scans were interpreted in a blind and independent fashion by 2 experienced observers. The final diagnosis was obtained with the histopathologic study or a microbiologic culture or with the clinical findings after a follow-up of at least 6 months. The sensitivity, specificity, positive and negative predictive values, and the positive and negative probability ratio were determined, always using a 95% confidence interval (CI). The sample size necessary to show 99% sensitivity with a 95% CI and a statistical power of 80% was 15 patients. The concordance with the kappa index was determined.
Results: Twenty-seven patients with suspected vertebral osteomyelitis were included; 15 males and 12 females, with a mean age of 50 years (SD = 16). Fourteen patients had a history of surgery and 12 had metallic implants. Nine patients had a history if spinal infiltrations. The number of patients with a positive scan was 20. The sensitivity for detecting pyogenic vertebral osteomyelitis was 100% (CI: 0.901-1) and the specificity was 87.5% (CI: 0.647-0.875). The positive predictive value was 0.95 (CI: 0.859-0.950), and the negative predictive value was 1 (CI: 0.739-1). The intra- and interobserver kappa value was 1.
Conclusions: The UBI scan showed 100% sensitivity and 88% specificity for vertebral osteomyelitis. Although the role of this method in the diagnostic protocol of the patient with suspected vertebral osteomyelitis has not yet been defined, the scan was useful in this group of patients to arrive at a certain diagnosis.