Your healthcare provider may ask for a CT scan to look for tumors in your colon and rectum. They may also want the scan to look for tumors in other parts of your body, such as your lymph nodes, lungs, or liver. The scan takes X-rays of your body from many angles.
Computed tomography (CT or CAT) scan
This test can help tell if colorectal cancer has spread to nearby lymph nodes or to your liver, lungs, or other organs.
Colorectal cancer is the 3rd most common type of cancer and the 3rd leading cause of cancer death in the United States. Colonoscopies have long been the standard screening procedure for detecting growths in the colon, but CT Colonography is a comparably accurate, non-invasive alternative.
Rationale. F‑18 FDG PET‑CT staging after endoscopy and whole-body CT allows the more accurate detection of metastatic disease. This helps to determine whether the disease is suitable for radical treatment, or whether it is too advanced.
CT colonography is a computed tomography ( CT ) examination to look at the large bowel (colon). It is a method of diagnosing bowel cancer when it is still at an early stage. A CT machine uses x-rays and advanced computers to create detailed images. We then examine these images to check the health of your bowel.
Reasons for the Scan
CT scans are commonly used by gastroenterologists to verify the presence or absence of tumors, infections, abnormalities, or to evaluate changes in the body due to trauma.
CT scans utilize X-rays to form images of organs and tissues inside the body (for example, abdominal organs, brain, chest, lungs, heart) while colonoscopy is a procedure that can visualize only the inside surface of the colon.
Treatment response: Sometimes doctors order a scan to see whether a tumor is responding to treatment. Tool for monitoring for other diseases: CT scans may be necessary to look for other conditions that may or may not be related to cancer, including: Abnormal brain function.
This procedure is used to check for stomach cancer. An upper endoscopy—called endoscopic gastroduodenoscopy (EGD)—is a procedure that helps find most stomach cancers. During this test, a doctor looks inside your stomach with a thin, lighted tube called an endoscope.
Both procedures are relatively risk-free, though CT does expose you to radiation (at a safe level), and endoscopy carries the risk of bowel perforation and anesthesia drug allergies. If a medical professional uses IV contrast dye to enhance CT images, some patients may be allergic to it or risk kidney damage.
A CT scan will identify inflamed diverticula, bowel wall inflammation, pericolic fat stranding, and corresponding complications [9,10,11,83,87,88]. CT is capable of visualizing pericolonic and colonic complications which results in a more accurate diagnosis for the patient, along with better standard of care.
CT scan accurately localized colon tumors in 52/104 (50.0%) of cases, incorrectly localized tumors in 18/104 (17.3%) of cases, and did not detect known tumors in 34/104 (32.7%) of cases. Of the 21 tumors erroneously located by colonoscopy, 11 (52.4%) were accurately localized by CT scan.
Endoscopy – quick review: CT scans utilize X-rays to form images of organs and tissues inside the body (for example, abdominal organs, brain, chest, lungs, heart) while endoscopy is a procedure that can visualize only the inside surface of the upper gastrointestinal tract.
Even with an endoscope, it can be difficult to distinguish cancerous lesions from healthy or scarred stomach tissue. Ngamruengphong explains why: “When we perform a screening endoscopy, we don't see a large mass when cancer is present. Instead, we often see very small, very subtle lesions.”
What is a combined Upper GI endoscopy and colonoscopy? These combined procedures may help to find the cause of your symptoms. An upper GI Endoscopy is a test that allows the endoscopist to look directly at the lining of the gullet (oesophagus), stomach, and first part of the small intestine (duodenum).
A CT scan may be ordered if your doctor suspects you have a tumor or blood clot. These issues could be a symptom of a very serious problem; therefore the sooner they are discovered the better off the patient will be. These scans may also be used to look for signs of an infection or any excess fluid.
Usually the radiologist will send a report to your GP or the doctor who referred you for the CT scan. It can take several days, or even a week or two, for your results to come through.
A biopsy is the only way to diagnose most cancers. Imaging tests like CT scans and X-rays may be used to help identify abnormal areas, but they can't differentiate between cancerous and noncancerous cells.
In a number of studies, CT colonography has displayed results equivalent to colonoscopy in both cancer and polyp detection. CT colonography has been shown to rapidly and effectively examine the entire colon for lesions.
Conclusion: CTC using 64-row multidetector CT is useful for colon cancer screening to detect colorectal polyps while the detection of small, flat lesions is still challenging.
A CT coronary angiogram is mainly used to check for narrowed or blocked arteries in the heart (coronary artery disease). However, it can check for other heart conditions. A CT coronary angiogram differs from a standard coronary angiogram.
CT scans expose you to more radiation than regular x-rays. Many x-rays or CT scans over time may increase your risk for cancer. However, the risk from any one scan is small. Most modern scanners are able to reduce the radiation exposure.