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@uky.campus.mci.net and
jmdurh1@pop.uky.edu
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