Examination of abdominal CT images obtained due to bowel disease in patients under follow-up at the ibd outpati̇ent clinic for osteoporosis

Aim: To determine the appropriate HU cut-off values for osteoporosis, osteopenia and normal BMD by comparing the HU values of L1-L4 vertebrae obtained from abdominal CT images with DXA T-score/Bone Mineral Density (BMD) in individuals with IBD follow-up, and to determine the frequency of decreased BMD in the whole group by this method. Materials and Methods: The imaging and laboratory results of 93 patients who underwent both DXA and abdominal CT scans with no more than a one-year interval between 2018 and 2022 were retrospectively analyzed through the electronic hospital system. Inflammatory Bowel Disease (IBD) parameters and demographic characteristics were obtained from outpatient clinic follow-up files. Results: When DXA and CT results were compared, a directly proportional relationship was found between BMD and L1-L4 mean HU values. It was observed that the average HU values of the lumbar vertebrae in individuals with osteoporosis and osteopenia were significantly lower than in individuals with normal BMD. L1-L4 mean HU ≤ 155 was associated with a 72.1 times increase in the risk of osteoporosis and had a sensitivity of 95.5%, specificity of 76.1%, and a negative predictive value of 98.2%. Mean HU ≥ 175 was found to have 91.7% sensitivity and 75.4% specificity, 70.2% positive predictive value, and 93% negative predictive value for normal BMD. Conclusion: HU values of lumbar vertebrae have high sensitivity and specificity in terms of BMD evaluation of individuals. By using this method in the diagnosis and follow-up process of inflammatory bowel diseases, we can reduce morbidities by early diagnosing low BMD through abdominal CT scans and decrease medical expenses by requiring fewer DXA scans. Keywords: Inflammatory Bowel Disease (IBD), Osteoporosis (OP), Osteopenia, Hounsfield unit (HU)