Lee SJ, Kim JY, Choi YY, et al. - This study was attempted to assess if the lesion-to-background ratio (LBR) of the whole spinal column in ankylosing spondylitis (AS) patients based on baseline F-18-fluoride positron emission tomography/computed tomography (PET/CT) is correlated with treatment response. Researchers recruited a total of 28 male patients with a wide range of disease activity in this study. They visually assessed abnormal bone metabolic lesions on baseline F-18-fluoride PET/CT in three areas: anterior discovertebral units (DVUs) and posterior joints (cervical, thoracic, and lumbar facet joints, costovertebral joints, and costotransverse joints) of vertebrae and sacroiliac joints of the sacrum. The findings reveal that LBR of posterior joints of the spinal column on baseline PET/CT could be considered one of the potential surrogate markers for prognosticating treatment response in patients with AS.