CT

COLONOGRAPH

Y

CRC TRENDS 1970-1990

Incidence decreased by 7% Mortality decreased by 20% Five year survival rates increased

by 12%

COLORECTAL CANCER

Lifetime risk for development 5% or 1:19

Lifetime risk for death : 2.5% Males slightly higher than

females 75% in average risk patients

LIMITED IMPACT

Only 37% of cases are diagnosed when the disease is localized

20% will have distant metastases at initial diagnosis

RISK FACTORS Age > 50 years ((90%) Familial factors: FAP, Gardner’s,

Ashkenazi Jews(APC gene), HNPCC

Racial group : African Personal or family hx : CRC 2-4x

or adenomatous polyp Personal hx: ovarian, endometrial

or breast cancer , chronic IBD > 10 years(UC>Crohn’s)

CRC RISK FACTORS

Low fiber, high fat diet High red meat consumption Inactivity, obesity Smoking Alcohol

CHEMO-PREVENTION OF CRC

Aspirin, NSAIDS Postmenopausal estrogen Calcium, Selenium Vitamins A, C, E and folic acid

ANATOMIC LOCATION OF CRC

Rectosigmoid: 52-61%

Ascending colon and cecum 19-24%

 

SCREENING TESTS FOR CRC

How accurate are they?

FIT ADVANTAGES

No dietary restrictions

Safe, non-invasive, no bowel prep

Inexpensive

Best study regarding impact on mortality

Fewer false positives from upper GI bleed

Sensitivity FIT vs gFOBT

82% vs 64% for colorectal cancer

30% vs 41% for adenomatous polyps 

FIT DISADVANTAGES

Most cancers bleed intermittently Most adenomas don’t bleed non-neoplastic : hemorrhoids,

NSAID

COLONOSCOPY

High sensitivity and specificity Sensitivity < 5 mm 73% 6-9 mm 87% > 10mm 94%

Gold standard for colon evaluation. For an average risk individual with a negative colonoscopy, further screening of any type is not required for 10 years.

COLONOSCOPY- LIMITATIONS

Variable patient compliance Requires IV sedation Costly Time-consuming Incomplete in 5-10% CRC localization accuracy 86%

INCOMPLETE COLONOSCOPY

Operator inexperience Poor bowel cleansing Redundant bowel Benign/malignant stricture Severe diverticulosis

COLONOSCOPY

COMPLICATIONS

Perforation dx 1/1000

tx 1/500 Bleeding 3/1000 Death 1-3/10 000

Death rate from colon cancer in 50-54 yo

is 1.8/10000

PERFORATION RATES

DCBE 1/25000

CTC 1/22000

FLEX SIGMOIDOSCOPY 1/10000

DIAG COLONOSCOPY 1/1000

THERAPEUTIC COLONOSCOPY 1/500

2009 ACR/CAR GUIDELINES

Indications

1) (screening) exam

2) surveillance exam

3) diagnostic exam

4) following incomplete colonoscopy

5) patients at risk for colonoscopy: sedation risk, anticoagulant therapy, prior incomplete colonoscopy , advanced age.

CTC PRO

minimally invasive low complication rate

(perforations 0.46 per 10,000) compared to colonoscopy24 

no sedation used usually effective where

colonoscopy is technically incomplete

also images extraluminal structures

CTC CON

discomfort radiation exposure reduced sensitivity for detection of flat

polyps and polyps <6 mm25  does not permit biopsy or polyp removal the accuracy depends on expertise of the

radiologist and adequacy of preparation there are currently no outcome studies

regarding CRC mortality prevention

RADIATION

Fixed KVp at 120kv but mA varies Linear relationship between mA

and patient dose Ultra - low dose ie 10-80mA

adequate for colon Symptomatic patients increase

mA for evaluation of extra-colonic findings

Colon ca staging use normal 220 mA for complete exam

2009 ACR GUIDELINES

ABSOLUTE CONTRA-INDICATIONS

1. routine f/u of IBD

2. hereditary polyposis or non-polyposis syndromes

3. evaluation of anal disease

4. pregnant patients

2009 ACR GUIDELINES

RELATIVE CONTRAINDICATIONS 1. symptomatic acute colitis

2. acute diarrhea

3. recent acute diverticulitis

4. symptomatic colon containing hernia

5. symptomatic or high grade SBO

6. recent colorectal surgery

7. deep biopsy or polypectomy

8. colon perforation

1

BOWEL PREP FOR CT COLONOGRAPHY PICOSALAX PREP

This preparation is for patients with normal or mildly impaired kidney function (GFR value of 30 or greater). If you are known to have serious kidney disease (GFR value of less than 30), have your doctor call the Medical Imaging Department for alternate preparation instructions.

Please follow the instructions in this brochure very carefully. The instructions have been tested to ensure they minimize discomfort while producing a clean bowel. An incompletely clean bowel may mean that the test will have to be repeated. More importantly, if the bowel is not clean, remaining stool can hide serious conditions that may be present.

1-2 weeks prior to your appointment, at a pharmacy purchase:

1. One box of PICOSALAX (may have to ask for this from pharmacist but it does not require a prescription). Ignore package insert and follow instructions below:

2. Two 10 mg BISACODYL rectal suppositories

3. Adult wet wipes which are more gentle than toilet paper (not hand wipes which are not designed for toilet use)

4. Straws

From Diagnostic Imaging at EKH, KGH, KBH, CDH, KLH, BDH pick up:

1. Oral Barium solution (approximately 200 ml in one bottle taken in two drinks). Ignore instructions on bottle.

2. Oral Telebrix/Gastrografin solution (total of 30 ml taken in one drink)

Clear Fluids List: water; juices without pulp such as white grape juice, cranberry or cranapple; decaffeinated coffee; decaffeinated soft drinks; popsicles and weak tea without milk or cream; broth; bouillon and juice based high calorie beverage (Boost – except chocolate).Avoid all milk products. Do not drink just water as you may feel faint.

Medications: You may continue to take all regular medications through out the preparation time. If you are on insulin, ask your physician about dose modifications.

Two Days Before The Test:

Have normal evening meal. After dinner have only items from the clear fluid list. Place Barium and Telebrix in the refrigerator.

Day Before Test:

Breakfast:

1. Dissolve first package of Picosalax in a glass of cold water stirring constantly for 2-3 minutes until all dissolved. If the solution heats while stirring, let it cool or add more cold water before drinking. Drink this glass followed by an equal or larger glass of juice. Drink 4 or 5 more glasses of clear fluid over the next hour. You will experience frequent bowel movements which may occur within an hour. Stay close to a washroom. Wet wipes are easier than toilet paper.

2. Take first 100 ml of Readi-Cat 1 hour after taking Picosalax. Easier to drink with a straw.

3. You can have other clear fluids listed previously.

Snack:

Popsicle or decaffeinated soft drink.

Lunch:

Broth, Bouillon or Boost (except chocolate).

Take remaining 100 ml of Readi-Cat.

Snack:

Popsicle or decaffeinated soft drink.

Dinner about 5 or 6 PM:

1. Take second package of Picosalax exactly as per breakfast instructions. If the solution heats while stirring, let it cool or add more cold water before drinking. Drink 4 or 5 glasses of clear fluid over the next hour. You will experience frequent bowel movements which may occur within an hour. Stay close to a washroom.

2. Can have other clear fluids as desired.

At 8 PM:

1. Mix all of Telebrix/Gastrografin with 8 ounces of clear fluid. Easier to drink with a straw.

2. Insert the first rectal suppository. This should empty your bowel of any residual fluid.

3. No fluids after midnight except sips of fluid for any medication in the AM.

Day of Test:

In AM about 2 hrs before test:

1. Insert second rectal suppository.

2. Sips of fluid for any normal medications as directed.

3. Try to empty bowel one last time just before the test to ensure little fluid is left before the test.

TECHNIQUE

Supine and prone imaging

Sometimes decubitus

IV buscopan

Co2 insufflation

BUSCOPAN CONTRA-INDICATIONS

Myastenia gravis Untreated narrow angle glaucoma Prostate hypertrophy with urinary

retention Stenotic lesions of the GI tract

Megacolon MI within past 6 months Tachycardia and angina

Congestive cardiac failure

The primary goal of CTC is to detect the precursor lesion of colorectal malignancy

POLYPS

4 types

Benign neoplastic ie adenoma

Non- neoplastic ie hyperplastic ,inflammatory, hamartomatous

Only 3% of adenomas will progress to malignancy

30-40% develop an adenoma by 60 yrs

ADENOMATOUS POLYPS

Dysplasia- mild, moderate, severe or high grade

3 histologic types:

Tubular 85% , < 10mm

Tubulovillous 10% , >10mm

Villous 5% , 10x increased chance malignancy than tubular, 75%>20mm

ADENOMA-CA PATHWAY

Ca risk increases with increasing size of polyp

<1% 6-9mm polyp

10% 10-20 mm polyp

10-50% >20mm polyp

RECOMMENDATIONS BCRS>10mm size - 10% chance malignancy

>20mm - 50% chance of malignancy

= colonoscopy

6-9mm - f/u CTC in 3 years, 0.7% cancer risk (not warranting colonoscopy/biopsy)

if 3 polyps found between 6-9mm size, risk malignancy is equivalent to 10mm polyp ie 10% needs colonoscopy

polyps less than 6mm size should not be reported, <0.1% risk malignancy

TUBULOVILLOUS ADENOMA. (A) ENDOLUMINAL 3D VIEW FROM CT COLONOGRAPHY SHOWS A 10-MM PEDUNCULATED POLYP WITH A WELL-DEFINED STALK. (B) AXIAL 2D VIEW SHOWS THE SAME PEDUNCULATED POLYP (ARROWHEAD). UNLIKE MOST OTHER PEDUNCULATED LESIONS, WHICH ARE MORE EASILY RECOGNIZED AS SUCH ON 3D VIEWS, THE STALK AND POLYP IN THIS CASE HAPPEN TO BE ALIGNED IN A STANDARD 2D PLANE.

TUBULOVILLOUS ADENOMA. (A) ENDOLUMINAL 3D VIEW FROM CT COLONOGRAPHY SHOWS A SESSILE, LOBULATED 20-MM POLYP EXTENDING FROM A COLONIC FOLD. (B) DIGITAL PHOTOGRAPH FROM OPTICAL COLONOSCOPY SHOWS THE SAME LOBULATED LESION.

VILLOUS ADENOMA. (A) ENDOLUMINAL 3D VIEW FROM CT COLONOGRAPHY SHOWS A 5-CM IRREGULAR CECAL MASS. THIS PAPILLARY APPEARANCE IS HIGHLY SUGGESTIVE OF A VILLOUS TUMOR. (B) AXIAL 2D IMAGE (WITHOUT ELECTRONIC CLEANSING OF OPACIFIED FLUID) SHOWS THE SAME IRREGULAR CECAL MASS (ARROWHEADS). (C) DIGITAL PHOTOGRAPH FROM OPTICAL COLONOSCOPY SHOWS THE PAPILLARY, FRONDLIKE NATURE OF THE MASS TO GREATER ADVANTAGE. THE LESION WAS NOT MALIGNANT DESPITE ITS LARGE SIZE.

MALIGNANT POLYP. ENDOLUMINAL 3D VIEW FROM CT COLONOGRAPHY IN A SYMPTOMATIC PATIENT SHOWS A LARGE SESSILE MASS, WHICH PROVED TO BE MALIGNANT.

INVASIVE ADENOCARCINOMA. (A) CONTRAST MATERIAL-ENHANCED 2D CURVED REFORMATTED IMAGE WITH SOFT-TISSUE WINDOWING SHOWS AN ANNULAR-CONSTRICTING MASS WITH SHOULDERING (ARROWHEADS) INVOLVING THE SIGMOID COLON. CROSS-SECTIONAL 2D VIEWS ARE MUCH MORE EFFECTIVE THAN ENDOLUMINAL DISPLAYS FOR DEPICTING INVASIVE MASS LESIONS. (B) DIGITAL PHOTOGRAPH FROM OPTICAL COLONOSCOPY SHOWS THE PROXIMAL ASPECT OF THE MASS.

HYPERPLASTIC POLYP. (A) ENDOLUMINAL 3D VIEW FROM CT COLONOGRAPHY SHOWS A 7-MM SESSILE SOFT-TISSUE LESION, WHICH IS INDISTINGUISHABLE FROM AN ADENOMATOUS POLYP. (B) DIGITAL PHOTOGRAPH FROM OPTICAL COLONOSCOPY SHOWS THE SAME SESSILE POLYP. RELIABLE DISTINCTION FROM AN ADENOMATOUS POLYP REQUIRES HISTOLOGIC ANALYSIS.

INTERNAL HEMORRHOIDS. (A) ENDOLUMINAL 3D VIEW FROM CT COLONOGRAPHY SHOWS A LARGE, CIRCUMFERENTIAL MASS AT THE ANORECTAL JUNCTION THAT SURROUNDS THE RECTAL CATHETER. (B) DIGITAL PHOTOGRAPH FROM OPTICAL COLONOSCOPY SHOWS INTERNAL HEMORRHOIDS, WHICH ARE AT LEAST PARTIALLY THROMBOSED, SURROUNDING THE COLONOSCOPE.

SIDE-BY-SIDE COMPARISON OF (INWARD) POLYP AND (OUTWARD) DIVERTICULUM. ENDOLUMINAL 3D VIEW FROM CT COLONOGRAPHY SHOWS A 16-MM TUBULAR ADENOMA (ARROW) ADJACENT TO A WIDE-MOUTH DIVERTICULUM (ARROWHEAD). THE VOLUME RENDERING AND LIGHTING DISPLAY USED HERE ALLOW FOR EASY DISTINCTION.