Colorectal cancer other imaging findings
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Saarah T. Alkhairy, M.D.
Overview
Other imaging tests that can be used for colorectal cancer are endoscopy, PET scan, barium study, and angiography.
Other Imaging Findings
Endoscopy
- A sigmoidoscopy checks for polyps and other abnormalities in the lower colon and rectum
- A colonoscopy checks for polyps and other abnormalities in the entire colon and rectum. A colonoscopy has the advantage that if polyps are found during the procedure they can be immediately removed, and the tissue can also be taken for biopsy. The American Society for Gastrointestinal Endoscopy has released quality indicators for screening colonoscopy, which include:[1]
- Documentation of prep quality
- Photo documentation of cecal intubation
- Withdrawal time of 6 minutes or more
- Adenoma detection rate of greater than 25% in males and 15% in females greater than 50 years old.
Virtual colonoscopy
This is also known as CT colonography. This replaces X-ray films in the double contrast barium enema (above) with a special computed tomography scan and requires special workstation software in order for the radiologist to interpret. This technique is approaching colonoscopy in sensitivity for polyps. However, any polyps found must still be removed by standard colonoscopy.
PET scan
Cancer cells in the body grow rapidly, so they absorb the radioactive sugar fluorodeoxyglucose or FDG used in positron emission tomography (PET). The location and extent of the tumor mass can be determined using a PET scan. Also, metastatic lesions and their locations can be assessed using a PET scan.
PET scans are evolving as a very useful modality for staging and assessment of colorectal cancers. PET-CT scan has the advantage tissue based resolution and is useful in detecting whole body metastasis.
Barium Study
First, an overnight preparation is taken to cleanse the colon. An enema containing barium sulfate is administered, then air is insufflated into the colon, distending it. The result is a thin layer of barium over the inner lining of the colon which is visible on X-ray films. A cancer or a precancerous polyp can be detected this way. This technique can miss the (less common) flat polyp. Barium study can be used to delineate the lesion preoperatively.
Angiography
A CT angiography or a MR angiography give information about the blood vessels in the liver without the need for a catheter.
References
- ↑ Rex DK, Petrini JL, Baron TH, Chak A, Cohen J, Deal SE; et al. (2006). "Quality indicators for colonoscopy". Am J Gastroenterol. 101 (4): 873–85. doi:10.1111/j.1572-0241.2006.00673.x. PMID 16635231.