Lymphoscintigraphy

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Lymphoscintigraphy

• SLN (Sentinel Lymph Node)
• And Breast (cancer)

2

• Flow Primary Exam defines the flow of the
  radiocolloid through the lymph chains which can
  reveal the following results
• Lymphedema
• Obstruction
• Leak
• Mapping determines the following
• Solid Epithelial Tumors
• SLN
• Selective lymphad Enctomy

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Early Lymphatic Research

• The following individuals were involved with
  initial lymphatic research
• 1653 T. Bartholin
• 1685-1770 H.F. LeDran
• 1890 Halstead

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SLN - Breast

• The SLN was defined in breast cancer by the
  following individuals
• 1907 Jaimseon and Dobson
• 1960 Gould Sentinal Node
• 1977 Cabanas
• 1977 Norton
• 1977 Ege

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Selective Lymphadenectomy

• In the lymphatic system cancer spreads through
  the lymph chains and usually resides in what is
  known as the sentinel node. Removal of this
  node can result in the following
• Improved Staging
• Decreased Surgical Morbidity
• Reduced Number Radical LN Dissections

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The Concept

• Lymphatic spread of cancer is not only orderly,
  but also predictable
• The histological status of the SLN is predictive
  of the status of the distant Lymph node basin
• Skip metastases practically do not exist and
  metastatic spread can be discovered via the SLN

7
The above diagram shows the SLN which
contains The cancerous cells. These cells then
spread down The lymphatic channels to other lymph
nodes (second, Third tiers)
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Patient Population

• Early Breast Cancer will have the following
• Clinically Negative Axilla
• Tier 1 less than 2 cm
• 75 will be lymph node negative, beyond the SLN

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Adjuvant Therapy

• Removal of the SLN

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Lymphatic Anatomy

• Accompany blood supply
• Ectoderm mammary gland is organ of
• skin - biologic unit
• Mammary lymph flow parallels lymph flow from skin

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Lymphatic Anatomy

• Subcutaneous plexus common drainage location
  does not predict basin
• Important for injection site

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Radipharmaceuticals

• Visualize lymphatic channels from site of
  intestinal administration to first LN encountered
• Biologic Trap
• Active phagocytes by macrophages

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Left Red dots idenfity radiocolloid migrating
into the afferent lymph from an intersitial
injection where they are trapped by the
macrophages Within the sinusoid spaces. Right
Magnification of a histoautoradiographh of the
sentinel node Black dots show retention of the
radioactive agent in the sinusoid spaces.
Defines the ability to use radiocolloid to
define the sentinel lymph node.
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Radiopharmacenticals

• Particle size
• Number of Particles (few)
• Specific Activity (high)
• Decrease heating time
• Too much clumping of the particles occurs after
  two hours of preparation

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Approximate Ranges of Particles Size For Various
Radiocolloids Estimates
Particle size varies in the different agents used
for this procedure. The next side discusses ideal
particle size.
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Ideal Drug

• Radiocolloid between 100 200 nanometer
• This is not currently available
• Radiocolloid not used is
• Tc 99m DTPA mannosyl dextrin
• Rapid clearance
• Low secondary LN accumulation

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Preferred Radiocolloid

• Filtered Tc99m sulfur colloid
• Filter allows for particles that are lt 30nm
• If unfiltered colloid is used the particles will
  not travel as well through the system
• It is also suggested that the colloid be no more
  than 2 hours post preparation

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Tc99m sulfur colloid

• Not FDA approved
• Filtered 220 nanometer
• 50 200 nanometer particle
• Not considered the ideal agent because of its size

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Technique

• Techniques that must be considered in this
  procedure are
• Site of the injection most important
• Volume limited mL
• Dose to be discussed
• Timing relative to surgery after injecting the
  agent and imaging the SLN the patient must be
  sent to surgery for removal of the radioactive
  node

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Site

• Types of injection that could be done
• Intratumeral Not acceptable
• Peritumeral IM LNs (not acceptable
• Intradermal Subremal Preferred
• The ideal injection is done just below skin which
  is then picked up by the lymphatic system
• Injections are done around the tumor site

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ROI 1 Shows the injection site ROI 2
Indicates the flow of the colloid through the
lymphatic channel ROI 3 indicates the sentinel
Node Graph displays the radiocolloid traveling
through the lymphatic system over time.
22
This slide shows the difference between colloid
size and its ability to flow through the
infected system. Note that as the size of the
particle increases, the amount of nodes that
light up decrease. Hence, smaller colloid size
is preferred when diagnosing disease.
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Procedure

• 0.2 ml preferred volume
• 0.5 mCi dose
• Injection is done just underneath the skin with
  numerous injections around the tumor site, in a
  circular pattern
• Massage breast after injection
• 90 Arm Abduction location of arm
• Dynamic /Static Dynamic process with static
  images are acquired
• ANT/LAO - images
• Mark patient mark the SLN when it is identified
• 2 Hours total time

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Other Components

• Vital Dye can also be used along with the
  radiocolloid
• Gamma probe is used in the OR to determine
  which nodes are radioactive. Those that are are
  then removed

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Success Rate

• Fraction of patients in whom this procedure has
  been preformed identify 97 99 of the SNL
• False Negative 1 4

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Cases
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• These images illustrate variable patterns of
  lymphatic drainage. Imaging times occurred
  between 31 to 60 min post intradermal injection
  of 99mTc-HSA nanocolloid
• (A) RAO view shows single lymphatic vessel
  leading to single sentinel lymph node, with
  serial visualization of subsequent tier nodes
• (B) LAO view shows 2 separate lymphatics leading
  through widely diverging pathways, to 2 separate
  but adjacent sentinel node and tier nodes
• (C) LAO view shows 3 separate lymphatics leading,
  through widely diverging pathways
• (D) RAO view shows multiple lymphatics leading
  from site of infection in outer upper quadrant to
  at least 3 separate sentinel nodes and subsequent
  tier nodes

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• This procedure done at UofL Hospital shows
• The injection site covered with a lead shield
• Over time the lymph chain is noted
• Sentinel node is defined

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• The first image (L) shows the injection site
  that is located
• POST. Because of the excessive activity this
  injection site it can be seen in the ANT image.
  Note that slightly distal from the injection site
  the SNL.
• Imaging is improved when (second image) A)
  the injection site is extracts and B) A
  transmission image is take with the Co-57 flood.
  
• In the last image (R) a transmission scan is
  done in the groin region to assure that there is
  no additional SNL.

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Melanoma Upper Back

• 40 year old male presented with superficial
  spreading malignant melanoma of the left upper
  back.
• On dynamic images there is tracer uptake inferior
  and lateral to the melanoma site. The intense
  focus is activity at the injection sites around
  the melanoma

Posterior Projection
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Melanoma Upper Back (Cont)

• Image on the left includes activity from a
  transmission source which helps to outline the
  body.
• There are 3 discrete foci of tracer uptake (shown
  by arrows) anterior, inferior and lateral to the
  injection sites (shown by arrowhead).
• Micrometatses were found in one of the marked
  lesions.

Anterior Projection Static Images
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Melanoma Left Cheek

• A lateral static image from patient who had a
  left cheek melanoma (arrowhead shows sites of
  injection) demonstrates tracer uptake in the
  submandibular and posterior cervical lymph nodes
  (shown by arrows).

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Pre-Operative Lymphatic Mapping Breast Cancer

• Cancer was on the lower side of the breast and
  was injected with the radiocolloid (the dark
  black area on the bottom of the breast). You can
  easily see that there are two lymphatics which
  leave the breast (labeled with blue L) and go to
  two distinct sentinel lymph nodes (SLN).

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Mapping

• The picture on the left shows a sentinel lymph
  node (N) which is tinted blue because it has
  taken up the blue dye which was injected around
  the breast cancer.
• The blue dye got there by traveling through the
  lymphatics which leave the breast and connect to
  the SLN. This picture shows the lymphatic vessel
  (L) with blue dye in it.

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Breast Lymphoscintigraphy

• Mapping of the breast is done in order to
  surgically remove the SLN
• This can be done with blue dye
• This can be done with radiocolloid and a gamma
  knife
• Usually both are done at the same time

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Other Applications

• This procedure may also be useful with the
  following cancers
• Malignant melanoma
• Breast CA
• Cervical CA/Vulval CA
• Colorectal CA
• Head and Neck CA
• Thyroid CA
• Gastrial/Esophageal CA
• Penile CA