CT Based Assessment of Sarcopenia and Its Association With Biologic Treatment Outcomes in Inflammatory Bowel Disease Patients

Inflammatory bowel disease (IBD) has a relapsing-remitting course which necessitates frequent follow-up examinations to monitor disease activity. Disease management was previously guided by patient reported symptoms, and treatment targets were based on symptom control. However, the patient's symptoms do not necessarily correspond to inflammatory activity and current guidelines recommend that management should be based on objective evaluations. Due to reduced food intake, intestinal malabsorption, chronic protein loss through the feces, and increased energy demands from hypermetabolism , patients with IBD may suffer from malnutrition, and sarcopenia, even during remission. In 2014, the Asian Working Group forSarcopenia defined sarcopenia as an age-related decline in skeletal muscle mass as well as muscle function (defined by muscle strength or physical performance). Sarcopenia has been associated with older age, but it is also a known complication of various chronic diseases, such as cirrhosis, intestinal disorders, chronic kidney disease, neurodegenerative diseases, and malignant tumors . Sarcopenia affects the prognosis of IBD and is recognized as a risk factor for surgery, hospitalization, and postoperative complications in patients with IBD. Skeletal muscle mass can be assessed using various methods, including bioelectrical impedance analysis (BIA) , dual-energy X-ray absorptiometry (DXA), computed tomography (CT), and magnetic resonance imaging (MRI). However each technique exhibits considerable variability and lacks established reference standards. The total skeletal muscle area measured by CT or MRI at the L3-L4 lumbar spine levels is regarded as the gold standard for assessing skeletal muscle mass. CT enterography (CTE) is a routine diagnostic procedure for and can be utilized to evaluate their skeletal muscle mass without the need for additional tests.