IMAGING TECHNIQUES
IMAGING THE BODY
Over the past two decades many
methods of imaging the body have
been developed and are now widely
used. These techniques have made it
possible to visualize internal structures
in a variety of ways. Today, in addition
to conventional X-rays (which primarily
show bones), techniques such as CT
scanning, radionuclide scanning,
ultrasound scanning, MRI, and PET
scanning are used to provide detailed
diagnostic pictures of soft tissues and
organs. The examples given here show
some of the different ways in which
the kidneys can be imaged.
X-RAYS
Radiopaque contrast media may be utilized to give distinct X-ray images of soft
tissues, as in intravenous urography, which is used to give clear images of the
kidneys and urinary tract.
L e ft u r e t e r
R i g h t r e n a l
p e l v i s
S t o n e
R i g h t u r e t e r
B l a d d e r
Intravenous urogram
This intravenous urogram
shows the renal pelvises
(urine-collecting areas ofthe
kidneys) and the ureters,
which have been filled with
contrast medium. In the right-
hand renal pelvis and ureter
(on the left ofthe urogram),
the medium has been
retained due to a kidney
stone blocking the ureter; the
stone appears as a small gap
in the ureter.
Others, such as ultrasound scanning and radionuclide
scanning, can produce images without the need ofa
computer for image processing, although one maybe
used for image enhancement.
SCANNING TECHNIQUES
The body, particularlythe soft tissues, can be imaged using
a variety ofmodern techniques. Some ofthese techniques,
such as CT scanning and MRI, rely on computers to process
the raw imaging data and produce the actual image.
L e f t k i d n e y
M e d u ll a o f
k i d n e y
C o r t e x o f
k i d n e y
R i g h t k i d n e
Radionuclide scanning
A radioactive substance is introduced into
the body, and the radiation emitted is
detected by a gamma camera, which then
converts it into an image. Active or overactive
cells will take up more ofthe substance, and
will appear brighter, than underactive cells.
This scan (taken from the back) shows healthy
kidneys. In each kidney, the medulla (central
part) has absorbed more ofthe radioactive
substance than the cortex (outer part).
K i d n e y
C y st
Ultrasound scanning
Ultra-high-frequency sound waves reflected from
tissues in the body are converted into an image
by special electronic equipment. This scan shows
a fluid-filled cyst inside a kidney; the cyst
appears as a dark area on the image.
L iv e r
R i g h t k i d n e y
( w ith t u m o u r )
S p l e e n
L e f t k i d n e y
C y s t i n l e f t
k i d n e y
S p i n e
CT scanning and MRI
These techniques produce cross-sectional images
(slices) or three-dimensional images of body structures.
This CT scan shows a cross-section through the body,
as seen from below; the front ofthe body is at the top
ofthe image. The right kidney (shown on the left of
the image) is enlarged and distorted by a tumour. The
left kidney has a cyst.
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