Folds Haustral

Non-specific abnormalities can be seen on plain films in patients with PMC. These findings include bowel dilatation, haustral fold thickening, thumbprinting, small bowel and colonic ileus. Rare complications of the disease can be seen and include toxic megacolon and perforation (Merine et al. 1987 Ros et al. 1996). 

Specific sonographic findings related to PMC include pronounced colic wall thickening related to oedema of the haustral folds and giving the accor-... 

Fig. 13.2. Pseudomembranous colitis affecting the right colon. Transverse view on B-mode imaging shows the accordion sign related to oedema of the haustral folds...

Fig. 13.4. A CT scan of the abdomen in a case of pseudomembranous colitis shows the accordion sign , due to contrast trapping between thickened haustral folds. In this case, pericolic fat stranding and ascites are also visible...

Studies have shown that most of the false-positives detected by CAD tend to exhibit polyp-like shapes, and the major causes of CAD false-positives are thickened haustral folds and retained stool (PiCKHARDT 2004 Yoshida et al. 2002a Yoshida et al. 2002b), which is similar to the cause of false-positives by human readers (Pickhardt 2004). An example of the breakdown of the false-positive sources is the following Approximately half (45%) of the false-positives are caused by folds or flexural pseudotumors. They consist of sharp folds at the sigmoid colon, folds prominent on the colonic wall, two converging folds, ends of folds in the tortuous colon, and folds in the not-well-distended colon. One fifth (20%) are caused by solid stool, which is often a major source of error for radiologists as well. Approximately 15% are caused by residual materials inside the small bowel and stomach, and 10% are... 

Fig. 3.1. a Coronal multiplanar reformat demonstrates a well-cleansed transverse colon with no layering fluid or residual solid stool, b Three-dimensional endoluminal view from the same patient showing normal haustral folds which are easily evaluated because of the absence of residual material... 

Fig. 5.1. A poorly distended sigmoid colon (arrows) resulting in bulbous haustral folds on this supine scan demonstrates how inadequate distension can thwart confident and time efficient interpretation. Subsequent optical colonoscopy was unremarkable...

A thickened fold in an otherwise well distended colon might therefore point to the correct diagnosis of a sessile polyp on a haustral fold (Fidler et al. 2004) (see also Fig. 8.18). 

Fig.8.11a,b. Sessile polyp located between a haustral fold. Polyps located between normal haustral folds are easy to detect on a axial 2D image arrow), and b corresponding endoluminal 3D image (arrow)... 

If the lesions are located between haustral folds, they appear as a small flat protuberance if they are located on haustral folds, or near haustral folds, they are associated with minimal fold irregularity if they arise from a haustral fold, they project into the lumen, creating a cigar-like appearance. 

The first 3D visualization method for CT colonogra-phy was adopted from conventional endoscopy, and has a similar disadvantage areas behind haustral folds are not easily visualized. As a consequence, in conventional 3D methods the colon needs to be evaluated in both antegrade and retrograde directions in order to visualize sufficient colonic surface. With a fly-through in one direction substantial parts of the colonic wall and therefore polyps will be obscured... 

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