Biomedical Engineering Reference
In-Depth Information
the anatomy. Tissues with different densities will exhibit
varying degrees of X-ray absorption. This is the most
common form of imaging technique used in clinical
practice.
MRA
Magnetic resonance angiography (MRA) is a noninvasive
method of vascular imaging and determination of internal
anatomy without injection of contrast media or radiation
exposure. The technique is used especially in cerebral
angiography, the radiography of the vascular system of
the brain, as well as for studies of other vascular
structures.
Angiography
Angiography is a radiographic technique where a radio-
opaque (i.e., visible on an X-ray) contrast material is
injected into a blood vessel for the purpose of identifying
its anatomy on X-ray. This technique is used to image
arteries in the brain, heart, kidneys, gastrointestinal tract,
aorta, neck (carotids), chest,
Ultrasound
limb, and pulmonary
Ultrasound imaging is technique in which high-frequency
sound waves are reflected from internal organs, and the
echo pattern is converted into a two-dimensional picture
of the structures beneath the transducer.
circuit.
Fluoroscopy
Minimally invasive surgical devices
Fluoroscopy is a form of diagnostic radiology that enables
the radiologist, with the aid of a contrast agent, to visu-
alize an organ or the area of concern in motion, via X-ray.
This contrast agent allows the image to be viewed clearly
on a television monitor or screen. Contrast agents, also
known as ''contrast media,'' can be introduced into the
body by injection, swallowing, or enema.
For many surgical procedures, the method of choice has
shifted from traditional open surgery to the use of less-
invasive means. Minimally invasive surgery is performed
with the aid of a viewing scope and specially designed
surgical instruments (Garrett HMS, 1994). The scope
allows the surgeon to perform major surgery through
several tiny openings without making a large incision.
These minimally invasive alternatives usually result in
decreased pain, scarring, and recovery time for the pa-
tient, as well as reduced health care costs.
Endoscopy is an examination of the interior organs and
body cavities, through a natural body opening or a surgical
incision, using a light and a rigid or flexible viewing in-
strument called an endoscope. The viewing component of
an endoscope is made up of hundreds of light-transmitting
glass fibers bundled tightly together.
Laparoscopy has become a common surgical tech-
nique in the OR (Brooks, 1994). This procedure is the
examination of the interior of the abdomen with a slen-
der endoscope, called a laparoscope. The laparoscope is
inserted through an incision in the abdominal wall in
order to perform surgery. Laparoscopic techniques are
performed to remove gall bladders, to perform antireflux
operations on the esophagus, and to remove organs such
as the adrenal glands. Although minimally invasive sur-
gery is beneficial for the patient, it is technologically
more demanding than traditional surgery. Special training
is required for clinicians, and the associated medical
technology is more advanced. A laparoscopic procedure
is usually performed with a mobile cart that is outfitted
with equipment for visualization, instruments for expo-
sure and manipulation, and equipment and instruments
for cutting and coagulation.
The equipment for viewing internal tissues and organs
include a light source with fiber-optics to transmit the
Computed tomography
Computed tomography is a diagnostic technique that uses
X-rays to acquire detailed information of soft tissue
structures, muscles, bones, and organs. It uses an X-ray
source that revolves around the object to be imaged. The
detector captures the rays (raw data) that penetrate
through the organs. The raw information is processed and
reconstructed using a computer algorithm to form images.
The images are in the form of cross-sectional slices. This
technology is particularly useful for producing images of
the brain.
MRI
Magnetic resonance imaging (MRI) is a noninvasive
method of imaging structures and soft tissues inside the
body. MRI imaging is very detailed and provides a high
degree of diagnostic accuracy, as compared to othermodes
of imaging. It is based on the principle that hydrogen
nuclei in a strong magnetic field absorb pulses of radio-
frequency energy and emit themas radiowaves, which can
be reconstructed into computerized images. The images
produced are of a high quality and give a good indication of
the properties of internal body parts. MRI is widely uti-
lized by many surgical specialties. It is particularly valu-
able for imaging soft tissue, the brain and spinal cord,
joints, and the abdomen.
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