The norm of the small bowel on computed tomography

Purpose of the study. Determination of normal thickness and contrast of the wall of the small bowel (SB) depending on the phase of digestion on computed tomography (CT).

Material and methods. We examined 358 patients aged 20 to 88 years. According to the results of the survey, patients are divided into two groups. The main group consisted of patients examined on an empty stomach (n = 329), and an additional group consisted of patients examined after eating (n = 29). A CT scan of the abdomen was performed with a cut-off thickness of not more than 2 mm and a bolus contrast enhancement (CE) with a nonionic contrast medium. The results of measurements of the wall thickness of the SB and the intensity of its contrast were subjected to grouping and statistical processing.

Results and discussion. According to the results of our study, the average value of the wall thickness of the SB is normally 3.1 ± 1.2 mm, with a tendency to decrease this indicator in the distal direction. The regularities of changes in the thickness and intensity of contrasting of the wall of the SB in the norm depending on the age and the last meal were determined. With increasing age, diffuse thinning of the SB wall occurs. Normally, after eating, there is a thickening of the SB wall to 4.6 ± 1.8 mm and an increase in the intensity of contrast, mediated by an increase in blood supply, with a density gradient of + 10%. After CE, the proximal sections of the SB are contrasting brighter than the distal. The gradient of contrastion of the proximal and distal parts of the SB increases after meals, is maximum in young patients and decreases with age.

Conclusion. In order to reliably differentiate the pathological thickening and change the contrasting of the SB wall from the physiological one, it is imperative to ascertain the time and nature of the last meal and to take into account the age of the patient. In "non-contact" patients, an indirect orientation is possible according to the degree of filling of the stomach and SB.

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