Lymphoscintigraphy
What is Lymphoscintigraphy?
Lymphoscintigraphy is a imaging technique used in diagnosis of lymphedema,
or lymphatic spread from different types of cancer. Primary lymphedema
occurs without obvious cause and can present at different stages. Secondary
lymphedema is a fairly common condition in people with or being treated
for breast, prostate, bladder, uterine, skin, or lymphatic cancer. The
condition is debilitating through cosmetic abnormalities and other complications
that arise.
In lymphedema the flow of lymph is hindered or blocked. There
are no drugs currently available in the U.S. to treat this disorder. One
treatment that seems promising is Complete Decongestive Physiotherapy.
The treatment and presentation are discussed in the Prevention, Etiology,
and Treatment of Lymphedema link. The diagnosis and follow-up of the treatment
are both greatly aided by lymphoscintigraphy. This technique involves dosing
the patient with a radiopharmaceutical that will be taken up in the lymphatic
system and then imaging the distribution with a gamma-camera. Images, such
as the above and to the right, are of great clinical value, despite the
poor resolution. These images are so important because the flow of the
lymph can be traced which gives great insight to the condition of the vessels.
The agents used and the technique are briefly discussed below. For more
information on this subject refer to the links below.
Agents
NOTE: Agents must have a particle size of <50nm or they will stay at
the site of injection.
-
99mTc-Antimony trisulfide colloid (no longer available--was the previous
agent of choice)
-
99mTc-Sulfur Colloid (current agent of choice)
-
99mTc-Sulfur microcolloid (Tc-sulfur colloid that has been filtered--<.22
microns size)
-
99mTc-HSA (Human Serum Albumin)
Imaging Technique
The following technique was taken from the Case
Study #2 link below. This technique may vary for the other scans such
as melanoma, other examples involving different types of scans can be viewed
in case study #2 link.
Evaluation of extremity lymphedema -
-
0.05 cc injections of Tc-99m Sulfur Colloid (0.22 micrometer filtered,
0.5 mCi per injection) are performed intradermally. 2 injections are performed
on the dorsum of the foot or hand. Injection of the contralateral extremity
provides a useful comparison.
-
Patient ambulates (~ 2 flights of stairs) to aid lymphatic return.
-
For lower extremity lymphoscintigraphy, sweeps are performed, leaving the
injection sites just out of the field of view, up through the chest, in
anterior and posterior projections, at a rate of 8 cm per minute.
-
Full body sweep images are obtained every 30 minutes x three, followed
by another set of images at three hours, and then as needed.
-
The end point of a normal exam occurs when the clinical question is answered
and the liver is visualized.
Links to other sites on the Web
Description
of the Chemistry and Agent Used
Case
Study #1 (H. Lee Moffit Cancer Center and Research Institute)
Description
of the Technique (Victoria Hospital)
Description
of Lymphedema (Lymphedema Association of Australia)
Case
Study #2 (Harvard)
Images
of different Radiopharmaceutical scans (University of Kentucky)
Intraoperative
Lymphatic Mapping (University of Texas)
Etiology,
Prevention, and Treatment of Lymphedema (Lerner Lymphedema Services)
Dextran
Lymphoscintigraphy (Mahidol University)
A Typical Gamma Camera
This page was created by chadp@lex.infi.net
and jmdurh1@pop.uky.edu
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