and classical anatomical patterns of lymphatic
drainage for melanomas of the head, neck and
trunk. The authors therefore recommend scinti-
graphy prior to biopsy or elective lymph node dis-
section for melanomas sited in these regions.
Further experience over a number of studies has
led to the recommendation that pre-operative
scintigraphy be performed for all patients
referred
for sentinel node biopsy [21].
Uren and co-workers have also investigated the
role of scintigraphy in melanoma in a number of
studies using
99m
Tc-antimony sulphide colloid
tracer injected intradermally; they encountered
significant variability in lymphatic drainage be-
tween individuals [14] and a number of new and
unexpected lymphatic drainage patterns contra-
dicting classical anatomical theory [14, 22 –25].
They report particular difficulties in the correct
interpretation of lymph node drainage from the
distal lower limb to multiple nodes in the groin,
and advocate the need for early imaging to
identify
the first draining node(s) only as true sentinel
nodes [7]. This finding is in agreement with that
reported by Taylor et al. [17].
Pijpers and group performed dynamic imaging
using intradermally administered technetium-
99m colloidal albumin (nanocolloid). They re-
ported that 39 of 41 patients (95%) demonstrated
uptake of tracer into the sentinel node within
20 min of injection [13] and together with other
workers define the first persisting focus of
tracer
accumulation to represent the true sentinel node,
ignoring any later foci. Rapid tracer uptake and
persisting retention are reported and are advocat-
ed as an advantageous feature of the particle size
range for the colloidal albumin used [10]. Some
spillover into satellite nodes is reported but is
not
felt to hinder correct interpretation when dynamic
image data are available to assist in
interpretation.
Sentinel Node Imaging in Breast Cancer
Ve ronesi and co-workers recently published a
series of 163 patients with breast cancer to whom
tracer was injected subdermally [16]. The kinetics
for this route of administration are known to
be more rapid, and the protocol included static
imaging between 15 min and 3 h post-injection.
The reported sensitivity in this study for
detection
and
this is particularly relevant in melanoma. It
can
readily demonstrate patterns of drainage,
revealing pathways taken by the tracer in its
migra-
tion from the injection site through the afferent
lymphatic vessels to the true sentinel node(s),
and
has proven useful in eliminating the possible con-
fusion caused by a second-echelon node concen-
trating tracer due to spillover from the true sen-
tinel node,and located more closely to the primary
tumour than the sentinel node [17].
A
significant additional advantage of sentinel
node imaging is its capability to demonstrate
nodes potentially undetectable with the gamma
detecting probe alone.This includes those sentinel
nodes sited very close to, or actually underlying,
the injection site [18],sentinel nodes located out
of
the expected lymph node basins and therefore
beyond defined investigative boundaries for intra-
operative probing,and finally those sentinel nodes
situated very deep to the skin surface and/or
demonstrating very low levels of tracer uptake.
The reproducibility of sentinel node imaging in
melanoma has been shown to be acceptable. Uren
and colleagues reported inter-observer agreement
for 83 of the 84 (99%) node groups visualised in
51
patients [14]. The reproducibility between re-
peated scintigraphic studies has been investigated
by
Mudun and co-workers [6], who found agree-
ment in 85% of 13 studies, and Kapteijn et al.
[19],
who reported agreement in 88% of 25 patients
investigated.
Sentinel Node Imaging in Malignant Melanoma
Reintgen et al. have stated that sentinel node
imaging acts as an indispensible “road map” for
the sentinel node technique, and is required to
identify all nodal basins at risk for metastatic
disease, to identify both the location and the
number of sentinel nodes, and to detect the pre-
sence of any in-transit nodes, where such nodes
are considered to represent sentinel nodes in
them-
selves [8]. Such in-transit nodes have been found
to
occur in 5% of patients studied [5]. Initial ex-
perience with the sentinel node technique in 82
pa-
tients with melanoma [20] revealed a 59% discor-
dance between scintigraphic findings illustrating
the drainage pathways for an intradermal
admin-
99m
Tc-sulphur colloid tracer
chapter
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