ByDr/ Mahmoud Elshamy MD

INTRODUCTIONColorectal carcinoma (CRC) is the Second

most common cancer in United States and second leading

cause of cancer related death

KentuckyAfrican Americans Caucasians

Inci

denc

e

64.4 53.1 61.2

Mor

talit

y

28.4 19.8 23

Colorectal Cancer Incidence & Mortality 2000-2003

Per

100

,000

United States

INTRODUCTIONThe benign colorectal polyp is the core of

colorectal cancer

HISTOLOGIC CLASSIFICATIONOF POLYPSAdenomas are one histologic subtype of

colorectal polyps.Other histologic subtypes include mucosal

polyps, hyperplastic/ serrated polyps, juvenile polyps, and inflammatory polyps.

In addition, certain types of polyps can arise from layers deeper than the mucosa, including lipomas, carcinoid tumors, gastrointestinal stromal tumors (GIST), and serosal lesions.

HISTOLOGIC CLASSIFICATIONOF POLYPS.Adenomas constitute approximately half of

colorectal polyps; hyperplastic and serrated lesions make up about one third or more; and mucosal polyps make up approximately 10%. The remaining histologic subtypes constitute only a tiny percentage.

The histologic classification of polyps cannot be reliably determined by gross evaluation either at endoscopy or at CTC; they require pathologic examination for final diagnosis.

POLYP MORPHOLOGY.Polyps measuring 3 cm are generally divided

into three major morphologic categories: sessile, pedunculated, and flat.

Invasive masses are generally bulky annular or semiannular tumors.

The ideal target for screening and prevention of colorectal cancer is the “advanced adenoma,” which is defined as an adenoma that is large (10 mm) and/or contains histologic findings of either high-grade dysplasia or a prominent villous component

Methods for ScreeningColonoscopyAir contrast barium enemaCT colonoscopy

Clinical Indications for Performing CTCSCREENING INDICATIONSAsymptomatic adults at average riskAsymptomatic patients with positive family history Asymptomatic patients at increased risk for colonoscopy DIAGNOSTIC INDICATIONSFollowing incomplete optical colonoscopyEvaluation of suspected submucosal lesionsSurveillance of unresected 6-9-mm polyps detected at

previous CTCUnexplained GI bleeding, iron deficiency anemia, or other GI

symptomsSymptomatic patients at increased risk for colonoscopySurveillance following resection of polyps or cancer

CTC TECHNICAL CONSIDERATIONSThe technique for CTC involves the following

steps: (1) Bowel preperation.(2) Colon insufflation. (3) Image acquisition.(4) Image processing and interpretation.

IMAGE PROCESSING AND INTERPRETATION

Large fl at hyperplasticpolyp detected at CTC screening. 3D endoluminal (A) and 2D transverse (B) CTC images show a large but relatively subtle 15-mm nonpolypypoid lesion (arrowheads) within the transverse colon. A central depressionis suggested on the 3D view. Thelesion was confirmed at same-day OC(C) and proved to be hyperplastic.

3D RECONSTRUCTION

3 D VIRTUAL Recontruction

3D RECONSTRUCTION

Detection RatesColonoscopy: Sensitivity of 88.2 (>10mm)

Sensitivity of 90.0 (<6mm)

CT colonoscopy: Sensitivity of 92.2 (>10mm) Sensitivity of 85.7 (<6mm)

Air contrast barium enema: failed to identify up to 50% of polyps greater than 10mm in diameter

Virtual vs. Optical ColonoscopyPatients reported less discomfort with virtual

colonoscopyShorter examination time with VC72.3% of patients preferred VC as screening

technique compared to 5% preferred CC as screening technique

More patients were willing to repeat a VC at shorter intervals than CC.

Benefits Of CT Virtual ColonographyFaster examination time and this is a non

invasive test. It provides three-dimensional images that

can depict many polyps and other lesions as clearly as when they are directly seen by optical Colonoscopy.

Reduced patient risk, CT Colonography has a markedly lower risk of perforating the colon than conventional Colonoscopy.

Limitations of CT VirtualColonographyCT Virtual Colonography is strictly a

diagnostic procedure. If any significant polyps are found, they will have to be removed by conventional colonoscopy.

The immediate risks of CTC include a small rate of perforation related to gas distension, which is lower than the risk from colonoscopy.

Potential long-term risk from radiation exposure.

Thank youDr/ Mahmoud Elshamy MD