How Doctors Look Inside The Body

Ruzanna Harutyunyan's picture
How Doctors Look Inside The Body

When questions-and-answers and a physical exam aren't enough, your doctor may send you for an imaging procedure to have a "look" inside your body. Because the array of imaging techniques can seem like an unintelligible string of alphabets, Beaumont radiologist Shashin Doshi, M.D., offers the following primer:

METHOD: MRI (magnetic resonance imaging)
HOW IT WORKS: magnetic waves interact with the water in your body to produce images
USED FOR: soft tissues throughout the body
LIMITATION: patient has to lie still for long periods
NEWER USES: gauge success of treatment for fibroids in the uterus; assess the heart muscle in people with unstable angina (chest pain); evaluation of hip joints; breast cancer detection and post-therapy evaluation
DID YOU KNOW?: after a stroke, MRI can show what parts of and to what extent a person's brain is damaged as well as how recently the stroke occurred


METHOD: CT (computed tomography)
HOW IT WORKS: a series of X-rays are stacked to create a 2-D or 3-D image
USED FOR: bone and soft tissues
LIMITATION: uses ionizing radiation
NEWER USES: virtual colonography (often incorrectly referred to as "colonoscopy") to detect pre-cancerous polyps non-invasively; assessing the nature of plaque in the arteries for the likelihood they'll rupture and cause a heart attack
DID YOU KNOW?: CT is often used for forensic, or investigative, purposes. For instance, it was used to clear five bats in the National Baseball Hall of Fame from homerun superstar Sammy Sosa after he shattered another bat during a game, revealing cork inside.

METHOD: ultrasound
HOW IT WORKS: sound waves produce echoes to evaluate the internal characteristics of various tissues and organs
USED FOR: soft tissues; obstetrical and fatal imaging; vascular studies
LIMITATION: not useful for the evaluation of bones
NEWER USES: guiding breast biopsy; wound healing; evaluating artificial hip joints
DID YOU KNOW?: Ultrasound uses the principles of sonar, which was developed for ships at sea.

METHOD: PET, positron emission tomography
HOW IT WORKS: sugar is "tagged" with a radioactive element and injected into the body to study the function of tumors or the function of the heart and brain
USED FOR: cancer, brain and heart evaluations
LIMITATION: use for each patient must be individually planned to ensure the best information to aid in his care. Uses radiation
NEWER USES: research at Beaumont and around the world increasingly uses PET to study the body at a molecular level
DID YOU KNOW?: the radioactive agents used in PET are made in a cyclotron

HOW IT WORKS: ionizing radiation passes through soft tissues and bone at varying degrees, exposing film to different amounts that show up as light and dark areas
USED FOR: bones and limited soft tissues
LIMITATION: uses ionizing radiation
NEWER USES: evaluation of stents placed in blood vessels in the legs, hips, lower abdomen and pelvis
DID YOU KNOW?: X-ray scanners are commonly used at airports and post offices to assess the safety of the contents of a package.