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19

NCCN Guidelines for Patients

®

:

Colon Cancer, Version 1.2017

2

Treatment planning

Needle biopsy

Some imaging tests use contrast. Contrast is a dye

that will be injected into your bloodstream. It makes

the pictures clearer. Some people have an allergic

reaction to the dye. Tell your doctor if you’ve had

problems with contrast in the past.

CT with contrast

CT (

c

omputed

t

omography) takes many pictures of

a body part using x-rays. A computer combines the

x-rays to make one detailed picture. The picture is

saved for later viewing by the radiologist.

CT is advised if the cancer has spread beyond the

second layer of your colon wall. Get scans of your

chest, abdomen, and pelvis. Contrast should be

used. The radiologist will look for cancer in nearby

and distant sites.

During the scan, you will need to lie face up on a

table. The table will move through the machine. As

the machine takes pictures, you may hear buzzing,

clicking, or whirring sounds.

You will be alone in the room during the test. In

a nearby room, the technician will operate the

machine. He or she will be able to see, hear, and

speak with you at all times. One scan is completed in

about 30 seconds. You will likely be able to resume

your activities right away unless you took a sedative.

MRI

MRI (

m

agnetic

r

esonance

i

maging) uses a magnetic

field and radio waves to make pictures. It is not

often used to plan treatment for colon cancer.

Your doctor may order an MRI if the CT scan was

unclear. Contrast should be used. For stages II or

III, CT without contrast may also be done if you can’t

receive CT contrast.

Getting MRI is much like getting CT. Except, you will

need to wear a coil device. The device covers your

body from below your chest to the top of your legs.

It sends and receives radio waves. Straps may be

used to help you stay in place. MRI may cause your

body to feel a bit warm.

PET/CT

Sometimes CT is combined with PET (

p

ositron

e

mission

t

omography). When used together, they

are called a PET/CT scan. PET/CT scan is not often

used to plan treatment for colon cancer.

There are three reasons why you may have a

PET/CT scan. PET/CT can show how big a tumor

is if you have metastases. PET/CT can also find

metastases other than in the liver that would exclude

surgery. Last, PET/CT may be an option if you can’t

receive contrast dye for CT or MRI.

PET/CT may be done with one or two machines

depending on the cancer center. For PET, a sugar

radiotracer will first be injected into your body. The

radiotracer is detected with a special camera during

the scan. Cancer cells appear brighter than normal

cells because they use sugar more quickly. PET can

show even small amounts of cancer.

Needle biopsy

Samples of tissue or fluid can sometimes be

removed from the body with a needle. This procedure

is called a needle biopsy. The methods of obtaining

samples with a needle differ based on the body

site. If your doctor suspects metastases, a needle

biopsy may be done. The samples will be sent to a

pathologist for cancer testing.