Part 1 looked at various uses of X-ray technology as well as ultrasound imaging. Cameras are an essential part of many medical diagnostics as well.
The lining of the esophagus, stomach, and first part of the small intestine are examined using Esophagogastroduodenoscopy (EGD). In this procedure, the scope (a video camera with light) is inserted through the esophagus (food pipe) to the stomach and duodenum (the first part of the small intestine).
In contrast, a lower gastrointestinal (GI) tract radiography, also called a lower GI or barium enema, uses X-ray with a barium contrast agent for a fluoroscopic examination of the large intestine.
Similar to the EGD, colonoscopy and sigmoidoscopy are screening tests that use a thin flexible tube with a camera at the end to look at the colon but differ in the areas they can see. The lower GI colonoscopy examines the entire colon, while a sigmoidoscopy covers only the lower part of the colon, also known as the rectum and sigmoid colon.
The sigmoidoscopy is a less invasive screening test but it only looks at part of the colon, so any cancers or polyps farther into the colon cannot be detected.
Beyond an upper and lower endoscopy, the PillCam, a vitamin-sized capsule with a video camera and light source, can directly visualize the small bowel and detect small bowel ulcerations that other imaging tests may miss. When swallowed, it passes through the patient to provide visual images of its journey.
Magnetic resonance imaging (MRI) is another alternative to X-ray-based analysis. Used since the late 1970s, MRI provides a clearer image of many body parts compared to an X-ray. An MRI machine uses a magnetic field and pulses of radio wave energy to make a computerized map of the part of the body being scanned.
An extension of this technology is functional magnetic resonance imaging, or fMRI, which identifies brain activity by analyzing oxygen-rich blood in the active part of the brain that shows up as a stronger signal on the scan image.