WHAT A HEALTH PROVIDER SEES
M edical Im aging
edical images give health providers a look inside the patient for diag-
nostic purposes. There are many types of images, and we will look at a
few common ones:
A single burst of X-rays passes through an area of the body and gets captured
on sensitive film or digital imaging device. Dense structures (for example,
bones) scatter X-rays and appear white. X-rays pass through less dense
areas, which appear dark. Chemicals that create contrast can
be injected to image tubular structures (for example, Gl
tract, blood vessels, ureters).
Magnetic resonance imaging (MRI)
A highly magnetic field aligns the protons in body
fluids of the exposed area, a pulse of radio waves
reads the pattern, and a computer constructs the
image. MRI is good for imaging soft tissues but not
Computed tomography (CT)
An X-ray beam traces an arc around a section of the body. Detec-
tors read the scattering and feed the information to a computer, which constructs
a sectional image of the body, where differing tissue densities show as shades of
gray. Sections can be assembled to reveal three-dimensional images of soft tissues
High-frequency sound waves are passed through and reflected by
tissues within the exposed area. A detector reads the reflection,
and a computer constructs an image (a sonogram). This is a safe,
non-invasive imaging method used most commonly to show fetal
development, growths (for example, tumors, cysts, stones), and
organ blood flow (Doppler ultrasound).
Small cameras with fiber-optic cables can be inserted into the airways (bronchoscopy),
abdominal cavity (laparoscopy), joints (arthroscopy), stomach (endoscopy), and large
intestine (colonoscopy— image shown). The images are fed to a computer or TV screen
Images, depending upon the type, can be interpreted by many health professionals.
1. A football player is injured, cannot stand on his
right leg when w eigh t is ap plied , and com plains of
pain. W hich im agin g technique(s) w ould you use to
determ ine w hether he broke his leg or ankle?
2. You susp ect that a wom an has a cyst (a sac with
a distinct connective tissue wall, containing fluid
or som e other material) on her right ovary. W hich
im agin g technique(s) w ould you use to confirm
your diagnosis? W hy?