Advanced Biology

Imaging Technology

Clinical Applications:

Imaging Technology

Why? • Imaging allows physicians to view

internal structures and diagnose diseases and conditions

• Technology has steadily improved throughout the 20th century

Background

•  X-Ray Technology – Discovered in 1895 by

Wilhelm Roentgen – X-rays are short wave,

high energy photons of light

– Have the ability to pass through solid objects

X-Rays

•  Bone, tissue and skin density determines how much energy is absorbed as X-rays pass through

•  A detector (or film) catches the X-rays and generates an image based on the level of x-ray absorption

Metal: absorbs most x-ray radiation

Bone and Teeth: absorbs a major portion of x-ray energy

Skin and Tissue: absorbs the least energy (hardest to see)

Um…did anybody see that extra pair of scissors…

Big Brain��� Small Brain

CT Scans

•  Computed Tomography •  Developed in early

1970s •  Utilizes X-ray

technology to view “slices” of internal structures

How CT works… •  Uses x-ray beams in a 360o rotation around the body to obtain 1mm slices of bone, tissue and blood vessels

•  Computers collect the individual slices and allows for manipulation on a computer screen

Special Features

•  Contrast agents (dyes) can be injected or introduced orally which will make specific tissues stand out on the CT film.

•  Radioactive substances are often used.

Common Dyes:

Iodine

Barium

This CT scan shows an adenocarcinoma, the most common form of lung cancer

Uses of CT Scans

Uses of CT Scans

This coronal CT scan shows the abdominopelvic cavity

M R I�Magnetic Resonance Imaging Developed in the early 1980s, MRI technology does not use harmful x-rays to generate an image of internal structures.

MRIs produce detailed internal images of bone, soft tissue, blood vessels and muscles.

How MRIs work…

•  Radio waves, stronger than the magnetic field of the earth, are sent through the body

•  The radio waves disrupts the nuclei of atoms causing them to emit their own radio waves

The water in cells is the source of radio waves in most tissues. The waves are captured and translated into an image by a computer.

MRI Images

Ultrasound •  Works by sending out high

frequency sound waves which are reflected off of internal body structures.

•  Reflected waves are received and analyzed by a computer to produce images on a screen.

•  Non-invasion, no side effects

Ultrasound Uses

•  This technology is most commonly used during pregnancy to view the developing fetus

It is also used to identify cysts and tumors in abdominal viscera

Olivia Morgan at 18 weeks

Echocardiogram •  Ultrasound of the heart •  Shows morphology of

the heart and how well blood flows through the heart

•  Used to diagnose malformed structures and inadequate blood supply

Nuclear Imaging Studies

Includes: •  Positron emission tomography (PET) •  Single photon emission computed tomography (SPECT) •  Cardiovascular imaging •  Bone scanning

•  Nuclear medicine uses radioactive substances to diagnose and treat disease

•  Uses gamma ray detectors and computers to generate images of the anatomy and physiology of the body

PET Scan •  Radioactive isotopes (carbon-11,

nitrogen-13, oxygen-15) are injected into the patient which emit gamma rays (give off positrons) when they decay

•  The gamma ray detector captures these rays, turns them into photons which are then translated into an image

•  Uses 360o rotational slices (like CT and MRI)

PET Scan Benefits of PET Scans: • Very detailed images • Can show function in real time –

demonstrate what occurs under different conditions

• No exposure to X-rays

Drawbacks: • Use of radioactive materials • Very expensive • Needs to be near a particle

accelerator to generate the short-lived radioactive isotopes I have no idea how this physics

s*** works – don’t even ask!)

Cardiovascular Imaging Nuclear Stress Test

• Uses imaging technology to view the heart at rest and under stress

•  Identifies changes in heart tissue when the heart is subject to stress

• Diagnoses cardiac disease, blocked arteries and abnormalities Uses radioactive thallium

•  The patient is give the radioactive tracer and images are taken while the patient is at rest (used as a control)

•  The patient exercises on a treadmill in a controlled environment while being watched by a doctor

•  The patient walks/runs at increasing speeds/elevations until they can no longer keep going

•  Heart rate and rhythm are recorded

•  Another set of images are then immediately taken to detect any changes in the workings of the heart

How it Works

Endoscopy Test that looks inside of the body with a long flexible tube that is swallowed.

The endoscope has a camera and a light that enables the doctor to look at the inside of the upper intestinal tract

Ooooh… a sphincter

The doctor takes biopsies of any abnormal looking tissues to study

Helps diagnose and treat ulcers, intestinal bleeding, esophagitis and heart burn, and gastritis.

Endoscopy

Bleeding Ulcer

Squamocellular cancer

Colonoscopy Examines the colon (large intestine) with a fiber optic camera on a flexible tube passed through the anus."

Indications for colonoscopy include gastrointestinal hemorrhage, unexplained changes in bowel habit or suspicion of malignancy. "

Often used to diagnose or rule out colon cancer, but is also frequently used to diagnose inflammatory bowel disease. "

Colonoscopy The Tools:"

• Colonoscope: long flexible tubular instrument which is inserted into the rectum. "• video visualization equipment: enables the physician to inspect the lining of the colon "

• Other instruments, such as biopsy forceps can be passed through the colonoscope to perform certain surgical procedures."