Lymphoscintigraphy

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Lymphoscintigraphy

• Stephen M. Karesh, PhD
• Loyola University Medical Center
• Maywood IL

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Lymphoscintigraphy What is It?

• Scintigraphic visualization of lymphatic
  drainage of a specific body site following
  intradermal injection of a radiolabeled colloid

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Lymphoscintigraphy Why Do It?

• Due to anomalous drainage patterns, it is
  impossible to simply look at the patient and know
  drainage patterns. Lympho-scintigraphy guides the
  surgeon to lymph nodes draining the area around
  the lesion- permits biopsy of correct nodes.

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LymphoscintigraphyHow does it work?

• 6-8 bubbles of Tc-99m colloid are injected
  intradermally around periphery of lesion. Each
  bubble contains 100 mCi in 100 ml, equivalent to
  1 mCi/ml

excised melanoma
100 mCi
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Lymphoscintigraphy of Malignant Melanoma

• Migration of colloid in lymphatics is often
  seen as early as 15 min post injection imaging
  is performed at various times post injection out
  to 24 hr if necessary.

lesion
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Lymphoscintigraphy of Breast Carcinoma
Migration of colloid in lymphatics to the
SENTINEL lymph node is often seen as early as 15
min post injection.
lesion
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Lymphoscintigraphy of Breast Carcinoma

• Deep vs Intradermal Injection
• Intradermal may be more painful
• More failures with deep
• Deep may show internal nodes better

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Lymphoscintigraphy ofInternal Mammary Node Chain

• Visualization of Tc-99m radiocolloid in
  internal mammary node chain following deep
  interstitial injection is optimal 2 hr post
  injection.

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Rationale for UsingTc-99m Sulfur Colloid

• For past 8 years, Tc-99m antimony trisulfide
  colloid (Tc-ATC) has been unavailable
  commercially. No other product can adequately
  assess lymphatic drainage in patients with
  malignant melanoma and other diseases involving
  lymphatic spread

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Difficulty in Using Tc-99m SC

• Successful lymphoscintigraphy requires only
  the very smallest colloid particles (lt0.1 mm).
  Tc-99m SC prepared by conventional methods
  results in unfavorable particle distribution-
  most particles are in range of 0.5-2.0 mm.

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Preparation Methods

• boiling water bath for 5-10 min
• microwave oven for 15-30 sec
• room temperature incubation for 1 hr

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Particle Size as f (Preparation Method)

• boiling water mostly larger particles
• microwave oven wide range of particles, many
  small
• room temp (1 hr) mostly larger particles

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Optimal Parameters for Routine Preparation for
Tc-99m SC

• in microwave oven, RCP gt 98 routinely obtained
  with 28 sec heating cycle at 1/2 power (275
  watts)
• in boiling water bath, RCP gt 98 routinely
  obtained with 5 min heating cycle at 100oC
• Our in-house specification RCP gt 96

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General Preparation Methodof Filtered Tc-99m SC

• reaction mixture heated in microwave oven with 28
  sec heating cycle at 1/2 power (275 watts) OR in
  boiling water bath with 5 min heating cycle at
  100oC
• reaction mixture buffered, cooled 5-10 min
• Tc-99m SC drawn into 10 ml syringe and filtered
  through a 0.2 mm terminal filter into a sterile
  evacuated vial.
• Filtration step is repeated to remove particles
  missed by first filtration

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Preparation Methods Removal of Large Particles

• Preferred method terminal filtration through
  a 0.2 mm disposable filter. Manufacturers Burron
  Medical, Gelman, Millipore

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Removal of Tc-99m SC Particles by Filtration

• filter pore size removed
• 0.05 mm 99
• 0.1 mm 99
• 0.2 mm 40-80

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Filter Setup
0.2 mm filter
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Evaluation of Microwave Oven Preparation Method
Parameters 28 sec at 1/2 power (275 watts)

• Initially after 1st filtration
  after 2nd filtration
• RCP RCP in filtrate RCP
  in filtrate 98.7 98.5 35
  98.0 30
• of total activity filtered

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Evaluation of Boiling Water Bath Preparation
Method
Parameters 5 min at 100oC n6

• initially after 1st filtration after 2nd
  filtration
• RCP RCP in filtrate RCP in
  filtrate
• 98.7 98.5 15 98.0 13
• of total activity filtered

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Graphic Representation of Filtration Data
Microwave oven Boiling Water Bath
Particles gt0.2 mm
Particles lt0.2 mm
Particles lt0.2 mm
Particles gt0.2 mm
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Optimal Preparation of 99mTc-SC for
Lymphoscintigraphy

• 1. microwave 5 ml of reaction mixture containing
  25 mCi 99mTcO4- for 28 sec at 1/2 power (275
  watts)
• 2. Add 1 ml of buffer, then cool for 5-10 min
• 3. Draw 99mTc-SC into 10 ml syringe
• 4. Filter through 0.2 mm filter into sterile evac
  vial
• 5. Repeat filtration step to remove residual
  large
• particles

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Clinical Study Patient WW
Patient History - 23 y/o male - melanoma on
right back, T2 level - injected with 5 x 100 mCi
of filtered Tc-99m SC
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Clinical Study Patient RC

• Patient History
• - 44 y/o male
• - malignant melanoma, left chest wall
• - 2 mCi of Tc-99m SC injected intradermally

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Clinical Study Patient RM

• Patient History
• - 72 y/o male
• - melanoma, lower right back, L1 level
• - 0.5 mCi of Tc-99m SC injected intradermally

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Clinical Study Patient JH
Patient History - 35 y/o female - melanoma,
lower right back - 0.5 mCi of Tc-99m SC injected
intradermally
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Sentinel Lymph Node Detection

• requires use of intraoperative probe
• can reduce OR time
• may help to stage cancer patients
• may reduce unnecessary surgery
• may reduce morbidity

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Summary and Conclusions
1. A simple, rapid, reliable method of preparing
Tc-99m SC suitable for performing high quality
lymphoscintigraphy studies has been
described. 2. This preparation can be performed
in any laboratory with readily available
materials and equipment. Capital equipment
investment is 100 for dedicated microwave oven.
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Summary and Conclusions

• 3. Clinical results using the double-filtered
  Tc-99m SC compares very favorably with studies
  performed with Tc-99m ATC
• 4. This easily prepared replacement for Tc-99m
  ATC enables every Nuclear Medicine Department to
  offer lymphoscintigraphy at minimal cost to
  surgeons and clinicians