MEDICAL INTERVENTIONSMRS. STEWART

CENTRAL MAGNET SCHOOL

Diagnostic Imaging

X-Ray

Noninvasive medical test used to produce images of the inside of the body to help diagnose medical conditions.

X-rays are a form of electromagnetic radiation that is sent through the body.

Structures that are dense, such as bone, will block most of the X-ray particles and appear white.

Metal and contrast media, a special dye used to highlight areas of the body, will appear white.

Structures containing air will appear black and muscle, fat, and fluid will appear gray.

X-Ray

Produces two-dimensional images.

Examines bones, teeth, lungs, breasts, heart, blood vessels, and the digestive tract.

Uses ionizing radiation which can increase risk of developing cancer.

©iStockphoto.com

X-Ray – The Procedure

X-ray is performed by a machine that sends individual X-ray particles, called photons, through the body. The photons pass

through the body and the resulting images are recorded on a computer or special film. ©iStockphoto.com

Advantages and Disadvantages

Advantages Quick, painless,

noninvasive test Relatively inexpensive

Cheaper than a CT or MRI – cheapest test that takes pictures of the body

Disadvantages Small amount of

radiation exposure Contrast materials

sometimes used might produce an allergic reaction

CT Scan – Computerized Tomography

Also called Computerized Axial Tomography (CAT Scan).

Noninvasive medical test used to produce images of the inside of the body to help diagnose and treat medical conditions.

A series of X-ray views taken from many different angles are combined to produce cross-sectional images of the bones and soft tissues inside your body.

CT Scan

Produces cross-sectional images of the body.

Examines the chest, abdomen, pelvis, spine, and other skeletal structures.

Uses ionizing radiation which can increase your risk of developing cancer.

©iStockphoto.com

CT Scan – The Procedure

CT scan is performed inside a large tube that looks like a large doughnut standing on its side, and the person lies on the table in the center. The X-ray tube rotates

around the body. The table slowly moves

through the inside of the machine.

Each rotation yields several images of thin slices of the body.

©iStockphoto.com

Advantages and Disadvantages

Advantages Painless, noninvasive,

and accurate test that is fast and simple

Able to image bone, soft tissue, and blood vessels all at the same time

Can be performed if patient has an implanted medical device of any kind

Disadvantages Small amount of

ionizing radiation exposure

Contrast materials sometimes used might produce an allergic reaction

MRI – Magnetic Resonance Imaging

Noninvasive medical test used to produce images of the inside of the body to help diagnose and treat medical conditions.

Unlike X-rays and CT scans, which use radiation, MRI uses powerful magnets and radio waves.

Detailed images produced of soft tissue, (versus X-rays and CT scans, which produce images of hard tissues such as bones and teeth).

MRI

Produces cross-sectional images of the body.

Used to examine the brain, spine, joint, abdomen, blood vessels, and pelvis.

Is very safe as the magnetic field itself does not hurt people (unless they have certain types of metal implanted in their body).

MRI brain scan

MRI – The Procedure

MRI scan is performed inside a large magnet, and the person lies on the table in the center. The machine scans the

body by turning small magnets on and off.

Radio waves are sent into the body.

The machine then receives returning radio waves and uses a computer to create pictures of the part of the body being scanned.

©iStockphoto.com

Advantages and Disadvantages

Advantages Noninvasive test that poses

almost no risk when safety guidelines are followed

Does not involve exposure to ionizing radiation

Images of the soft tissue structures of the body are more likely to identify and accurately characterize diseases than other imaging methods

Contrast materials sometimes used less likely to produce an allergic reaction than those used in x-rays and CT scans

Disadvantages Implanted medical devices

that contain metal may malfunction or cause problems during an MRI exam

Very slight risk of an allergic reaction if contrast material is injected

Confined space may induce panic or feelings of claustrophobia in some patients

CT vs. MRI

Both provide a cross-sectional view creating a 3D image

CT is faster and less expensive

MRI provides a more detailed view than a CT for soft tissue

Cross – section view

CT vs. MRI vs. XRay

Xray is least expensive of the 3MRI is more expensive than a CT

CT is safest to use on patients when medical history is unknown

CT is quicker than an MRIMRI provides a better/more detailed

picture than a CT

Xray is 2D; CT and MRI provide 3D images

Bone Scan

Noninvasive medical test used to produce images of the bones that help diagnose and track several types of bone disease.

Bone scan is a nuclear imaging test.

Bone Scan

Produces 2D images of the entire skeleton.

Used to detect abnormalities.

Tiny amounts of radioactive tracers (radionuclides) are injected into the body These will be absorbed by

bone cells that are doing the most growth and metabolism

These tracers will cause dark spots on the scan where they are absorbed most

©iStockphoto.com

Notice how the darkest areas are those experiencing the most growth in this adolescent – right on the growth plates

Bone Scan Identifying a Tumor on Shoulder

Bone Scan – The Procedure

An injection of tracers is administered to the patient and allowed to circulate and be absorbed by the bones.

Once absorbed, the patient lies on a table while a machine passes a gamma camera over the body to record the pattern of tracer absorption by the bones.

Radiologists look for abnormal bone metabolism on the scan, areas that show up as darker or lighter where tracers have or have not accumulated.

Advantages and Disadvantages

Advantages Noninvasive Extremely sensitive

to abnormalities and variations in bone metabolism

Can scan the entire skeleton

Disadvantages Cannot determine

cause of bone metabolism abnormalities

Tracers used produce a small amount of radiation exposure

PET Scan

A positron emission tomography (PET) scan is an imaging test that uses a radioactive substance called a tracer to look for disease in the body.

A PET scan shows how organs and tissues are working.

Sugar and radioactive tracers are injected together.

A PET scan can reveal the size, shape, position, and some function of organs.

This test can be used to: Check brain function Diagnose cancer, heart

problems, and brain disorders

See how far cancer has spread

Show areas in which there is poor blood flow to the heart

PET Scan

Application Questions

A patient enters a hospital after hitting her head in a car accident. She is diagnosed with a fractured skull but has other symptoms that she is suffering from brain damage. What technology should be used to confirm this diagnosis? Does it make a difference if I tell you this patient has

screws in her left knee after a bad break as a kid?

Application Questions

Design a patient situation where it would be inappropriate to use an MRI scan as a diagnostic tool

Application Questions

Evaluate the Dr’s reason for using a combination of X-rays, CT scans, bone scans and MRI scans when diagnosing Mike’s osteosarcoma (bone cancer).

Application Questions

Why do you think patient’s are often fearful of having an MRI or CT scan?

Application Questions

MRI

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