Bowel wall thickening at CT: simplifying the diagnosis

Abstract

ObjectiveIn this article we present a simplified algorithm-based approach to the thickening of the small and large bowel wall detected on routine computed tomography (CT) of the abdomen.BackgroundThickening of the small or large bowel wall may be caused by neoplastic, inflammatory, infectious, or ischaemic conditions. First, distinction should be made between focal and segmental or diffuse wall thickening. In cases of focal thickening further analysis of the wall symmetry and perienteric anomalies allows distinguishing between neoplasms and inflammatory conditions. In cases of segmental or diffuse thickening, the pattern of attenuation in light of clinical findings helps narrowing the differential diagnosis.ConclusionFocal bowel wall thickening may be caused by tumours or inflammatory conditions. Bowel tumours may appear as either regular and symmetric or irregular or asymmetric thickening. When fat stranding is disproportionately more severe than the degree of wall thickening, inflammatory conditions are more likely. With the exception of lymphoma, segmental or diffuse wall thickening is usually caused by benign conditions, such as ischaemic, infectious and inflammatory diseases.Key points• Thickening of the bowel wall may be focal (<5 cm) and segmental or diffuse (6-40 cm or >40 cm) in extension.• Focal, irregular and asymmetrical thickening of the bowel wall suggests a malignancy.• Perienteric fat stranding disproportionally more severe than the degree of wall thickening suggests an inflammatory condition.• Regular, symmetric and homogeneous wall thickening is more frequently due to benign conditions, but can also be caused by neoplasms such as well-differentiated adenocarcinoma and lymphoma.• Segmental or diffuse bowel wall thickening is usually caused by ischaemic, inflammatory or infectious conditions and the attenuation pattern is helpful in narrowing the differential diagnosis.

Evaluation of Bowel Wall Thickening by Computed Tomography to Differentiate Benign from Malignant Lesions

“…The mucosa is the most intensely enhancing layer of the bowel wall and when enhanced may appear as a distinct layer. In contrast, the submucosa is less vascularised and is seldom seen as a separate structure on CT scans unless it is oedematous, haemorrhagic or infiltrated by fat [8,2]. If the bowel wall is enhanced to a degree that is equal to or greater than that of venous opacification in the same scan, it should be classified in the white attenuation pattern [9] [Table/ Fig-4].…”

“…The GI tract can be difficult to evaluate because it is actively peristalting [1]. Multidetector CT (MDCT) makes possible the acquisition of isotropic data and affords the capability of performing high resolution multiplanar reconstructions [2]. 3-D interactive workstations and advanced software have considerably improved lesion conspicuity and even provide virtual endoscopy of bowel.…”

“…CT cannot demonstrate subtle superficial mucosal changes revealed on barium studies, but is a highly sensitive method for detection of intramural disease and extramural extension of colonic disease [4]. In particular, CT enterography acquired after luminal distension through the administration of high volumes of neutral contrast material (1,500-2,000ml of water, watermethylcellulose solution, polyethylene glycol electrolyte solution or low-concentration barium) is helpful in displaying the thickness and enhancement of the small bowel wall [2,5]. Presently, CT is considered a first-line modality for evaluation of a variety of small bowel diseases [3].…”

The Diagnostic Significance of Bowel Wall Thickening for Inflammatory Bowel Disease

“…BBT'deki ince barsak duvar kalınlığı 3 mm'yi, kolon duvar kalınlığı lüminal distansiyon mevcutken 1-2 mm, distansiyon yokken 5 mm'yi geçtiğinde BDK artmış olarak kabul edildi. 7 …”

“…Bunun nedeni; barsak lümen distansiyonu, alınan oral kontrastın lümeni homojen doldurmaması veya lü-mende birikmiş gıda parçaları, feçes, hava veya sı-vıya bağlı nedenlerden dolayı yalancı duvar kalınlaşması olabilir. 7 Bu hastaların klinik izlemlerinde patolojik bir bulguya rastlanmamıştır.…”