Our study aims to investigate the incidence of sarcopenia in Patients with IBD using CT-based body composition parameters, observe the interaction between sarcopenia and IBD treatment, and determine whether sarcopenia affects the response to biologic therapies

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.

Inclusion Criteria:

• Patient above age of 18 years old
• diagnosed to have IBD through: clinical features, endoscopic findings
• received biological therapy

Exclusion Criteria:

• Patients with UC who are under age of 18 years old.
• Pregnancy.
• Previous colectomy.
• Patient refuse to participate in the study

• Thorough medical history, anthropometric measurements (weight, height, waist circumference, BMI), and physical examination (general and abdominal) stressing on significant weight loss.
• Laboratory investigations (Complete blood picture, Liver function tests, C-reactive protein and ESR, Fecal calprotectin) and colonoscopy will done with assessment of severity .
• CT examination will performed following the standard imaging protocol. At the level of the third lumbar vertebra, the boundaries of skeletal muscles were manually outlined using Image J software version 1.54p. Throughout the study, the boundaries of skeletal muscles were determined by trained radiologists. Pre-defined radiation attenuation ranges are used to demarcate muscle (-29 Hounsfield units to +150 Hounsfield units). Calculate the skeletal muscle area (SMA) in square centimeters from the pixel count using ImageJ.