Certain Investigation Titles on the Segmentation of Colon and Removal of Opacified Fluid for Virtual Colonoscopy

Introduction

Colorectal Cancer (CRC) is a type of cancerous growth that develops in the colon or in the rectum, as shown in Figure 1. The Gastrointestinal (GI) system composed of colon and rectum are important parts of the digestive system. The probability of the occurrence of the cancer in the small intestine (bowels) is minimal when compared to the large intestine (colon), a muscular tube approximately 5 feet long in the region or in the rectum. The structure of the colon is comprised of four portions,

Figure 1.

Detailed Anatomy of the colon and rectum

• 1.

  Ascending colon is located between a pouch called the cecum where the undigested food enters and the transverse colon. This branch of colon will extend upwards and terminate at a right colic flexure on the right side of the abdomen as shown in the Figure 1.

• 2.

  The transverse colon which is the longest part will bend downwards as it traverses from right to left for a short distance and it will bend upwards to form a U shaped curve. This part of the curve will finish below the spleen to form another flexure called splenic or left colic flexure.

• 3.

  The above section will be continued by the descending colon. As its name implies, this segment will descend from the splenic flexure to the lower level on the left side.

• 4.

  The fourth part is called the sigmoid colon for the reason that this segment will be of “S” shape; the sigmoid colon joins the rectum, which in turn will connect to the anus.

Different radiological procedures and imaging modalities widely used to identify CRC are computed tomography (CT), virtual computed tomography colonoscopy, endorectal ultrasound, and magnetic resonance imaging (MRI).Among these techniques CT has been preferred due to following reasons:

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  CT is a preferred examination technique for investigation of abdominal organs for elderly patients even if they have an implanted medical device of any kind.

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  It causes less pain for the complete assessment of the large bowels and small bowels where air or carbon dioxide is injected in the rectum via thin catheter. It is accurate, non-invasive, less sensitive to patient movement, fast and simple.

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  The results of this screening technique can be diagnosed by an experienced radiologist with very high accuracy so the patients can be guided for further treatment and this technique eliminates the need for additional diagnostic procedures such as needle biopsies, exploratory surgery and surgical biopsy.

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  If a large growth is identified during colonoscopy, then CT colonography (CTC) can be recommended on the same day for a detailed analysis of the colon.

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  The cost of CTC is significantly when compared to other investigation techniques.

Cad Techniques To Investigate The Polyp (Growth) In Ctc

The segmentation of colon is one of the imperative step in the CAD techniques for the identification of polyps or growth in CTC. The size of a detected polyp is a significant norm for future diagnosis and decision making (John & Bond, 2000; Richardson et al., 2011). Polyps were classified as small (≤ 5 mm), medium (6-9 mm) and large (≥10 mm).Polyp size measurement from 6mm to 10 mm is to be considered. CAD is fundamentally based on highly complex pattern recognition. In recent years a number of prototype Colon CAD schemes with CTC have been proposed for detecting polyps to reduce the False Positive (FP) polyps (Bevilacqua et al., 2013; Bernal et al., 2012).The various CAD schemes that requires the segmentation of colon to be accurate are listed below for the identification of polyps