Dr. Cynthia Walsh Department of Radiology

 To learn the imaging modality best to SCREEN for Colon Cancer  To learn the imaging modality best to SCREEN for colon polyps  To learn the imaging modality best to STAGE Colon Cancer

1. Three test questions “pre talk” 2. Overview of imaging modalities for colon cancer and colon polyps 3. Double contrast barium enema 4. CT Colonograpy 5. CT for extracolonic pathology 6. Three test questions “post talk”

A 70 year old male has iron deficiency anemia is anticoagulated because of prior strokes. Colonoscopy requires discontinuation of anticoagulation. The neurologist does not feel that the anticoagulation should be discontinued due to the risk profile. The most appropriate imaging modality to SCREEN for colon cancer or polyps would be: 1. Double Contrast Barium Enema 2. CT with IV and Oral Contrast 3. CT Colonography 4. Radiologist supervised ultrasound with attention to the colon.

An advantage of CT Colonography (CTC) over Double Contrast Barium Enema (DCBE) is: 1. CTC does not require a bowel preparation 2. CTC does not use ionizing radiation 3. As colon distension is not required for CTC, it can be used in the setting of acute colitis. 4. CTC has better sensitivity and specificity for colon polyps compared to DCBE

A 65 year old female undergoes colonoscopy which reveals a colon cancer in the distal descending colon. The colonoscopy is incomplete as it cannot get past the mass (i.e. the colon proximal to the mass is not visualized). The most appropriate next management step is: 1. Surgical Consult for resection of the colon cancer. 2. CT with IV contrast to exclude metastases 3. CT Colonography (if so…why?) 4. Ultrasound to exclude liver metastases

Colon Cancer and colon polyps Imaging Modality Recommended: SCREENING -CT Colonography (if colonoscopy is incomplete, contraindicated or not possible) -CT Colonography is a specialized CT which focuses on the bowel. -Requires a bowel prep and colon distension - Barium Enema nearly obsolete STAGING of known colon cancer -Routine CT with IV Contrast

Double Contrast Barium Enema: Double Contrast Barium Enema: pedunculated polyps Polyp head Polyp stalk

Double Contrast Barium Enema: - Double Contrast Barium Enema: - sessile polyps

 CT which focuses on the colon  How is CTC done? 1. Requires a bowel preparation (the same as colonoscopy)  Often the most difficult part of the exam 2. Rectal tube placed in rectum 3. Colon distended with room air or CO2  Contraindicated in acute colitis 4. Do a CT scan in TWO positions (Routine CT uses only one position)  PRO’s 1. CTC is superior to Barium Enema  Better sensitivity and specificity 2. Identifies extracolonic pathology (lymphadenopathy, liver metastases)  CON : Uses ionizing radiation

Routine CT  No distension of the colon  No bowel preparation  NOT sensitive for identifying polyps and relatively poor for colon cancer. Therefore, Routine CT is NOT sufficient to exclude colon polyps or cancer.

CT Colonography has largely replaced Double Contrast Barium Enema for evaluation of colon neoplasia ( polyps and cancer )  Practices vary between institutions.  At TOH, Barium Enema is no longer performed to diagnose colonic neoplasia except under special circumstances.

CT Colonography Computer software traces a line through the dilated colon

CT Colonography Computer software traces a line through the dilated colon 3D endoluminal views

CT Colonography Computer software traces a line through the dilated colon 3D endoluminal views 2D images

Endoluminal View Polyp on CT Colonography

CT Colonography - Polyp on 3D views CT ColonographyColonoscopy

Colon cancer Invading the right kidney

Obstructing Cancer in the transverse colon with a liver metastasis  CT Colonography can show colonic and extracolonic pathology liver metastasis Transverse colon cancer

A 70 year old male has iron deficiency anemia is anticoagulated because of prior strokes. Colonoscopy requires discontinuation of anticoagulation. The neurologist does not feel that the anticoagulation should be discontinued due to the risk profile. The most appropriate imaging modality to SCREEN for colon cancer or polyps would be: 1. Double Contrast Barium Enema 2. CT with IV and Oral Contrast 3. CT Colonography 4. Radiologist supervised ultrasound with attention to the colon.

An advantage of CT Colonography (CTC) over Double Contrast Barium Enema (DCBE) is: 1. CTC does not require a bowel preparation 2. CTC does not use ionizing radiation 3. As colon distension is not required for CTC, it can be used in the setting of acute colitis. 4. CTC has better sensitivity and specificity for colon polyps compared to DCBE

A 65 year old female undergoes colonoscopy which reveals a colon cancer in the distal descending colon. The colonoscopy is incomplete as it cannot get past the mass (i.e. the colon proximal to the mass is not visualized). The most appropriate next management step is: 1. Surgical Consult for resection of the colon cancer. 2. CT with IV contrast to exclude metastases 3. CT Colonography (if so…why?) 4. Ultrasound to exclude liver metastases

A 65 year old female undergoes colonoscopy which reveals a colon cancer in the distal descending colon. The colonoscopy is incomplete as it cannot get past the mass (i.e. the colon proximal to the mass is not visualized). The most appropriate next management step is: CT Colonography (if so…why?) -This single test will complete screening of the colon proximal to the obstruction (i.e. exclude synchronous cancer or polyps) AND stage the malignancy (liver and nodal metastases).

 To learn the imaging modality best to screen for Colon Cancer  CT Colonography (has almost replaced Double Contrast Barium Enema)  To learn the imaging modality best to screen for colon polyps  CT Colonography (has almost replaced Double Contrast Barium Enema)  To learn the imaging modality best to stage Colon Cancer  CT with IV contrast