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Imaging Techniques

tiple lymph nodes [11]. Statman and Guiliano cite

their use of scintigraphy for selected inner qua-

drant breast tumours to establish the presence

of drainage to the internal mammary node chain

[12]; if this is seen they then perform interopera-

tive lymphatic mapping to identify and biopsy the

internal mammary sentinel node. Pre-operative

marking of the location of the sentinel node can

assist in guiding the site of incision for biopsy,and

a number of standard techniques exist to facilitate

accurate localisation of the sentinel node from

the image data acquired. A clinical benefit to the

patient then ensues, and it is stated that the effi-

ciency of the technique is increased [13].

Scintigraphic visualisation of the sentinel node

is technically straightforward and is a highly

sensitive procedure if meticulous technique is

observed. Specific guidelines are detailed later.The

image data can be easily and relatively rapidly

acquired. All lymph node basins under suspicion

as potential pathways for drainage of the radio-

labelled tracer from the primary tumour site may

be investigated, thereby revealing the total popula-

tion of functioning sentinel nodes.A sensitivity of

94% has been reported by Uren and co-workers in

imaging 209 patients with melanoma [14]. Pijpers

et al. reported the visualisation of sentinel nodes

in all of 135 patients with melanoma [10], and

Kapteijn et al. observed at least one sentinel node

in 59 of 60 patients (98 %) [15]. In their investiga-

tion of the sentinel node technique in breast

cancer, Veronesi et al. [16] indicated successful

identification of the sentinel node in 160 of 163

patients with breast cancer (98%) and Borgstein et

al.reported that the sentinel node was successfully

demonstrated in 116 of 130 patients (89%) [11].

Dynamic imaging also allows a more careful

interpretation through study of the kinetics of the

colloidal tracer immediately after administration,

Introduction

Wo rldwide a number of groups are currently eval-

uating, refining and establishing the sentinel node

biopsy technique as clinical practice. The pioneer-

ing work of Morton introduced intra-operative

lymphatic mapping by injection of a vital blue dye

into tissue surrounding the tumour, thereby en-

abling detection of the sentinel node visually by

dissection along the blue-stained afferent lym-

phatic vessel to the first draining node [1]. An

alternative approach was developed by Krag and

co-workers [2–4], who detected the sentinel node

after the injection of a radiolabelled colloid by

means of a hand-held surgical gamma detecting

probe. The pattern of lymphatic drainage of a

radiocolloidal tracer in melanoma has been im-

aged pre-operatively both as an initial step in the

radionuclide-guided detection of the sentinel

node [5, 6] and as a complement to the technique

of intra-operative lymphatic mapping [1, 7].

Sentinel node imaging is regarded by a number

of workers as an essential component of the

sentinel node technique, being fundamental to

achieving the highest possible sensitivity for

detection of sentinel nodes in both melanoma and

breast cancer. Reintgen and colleagues [8], Uren

and co-workers [7, 9] and Pijpers and group [10]

have all stressed the critical role of imaging in the

successful identification of functional sentinel

nodes in melanoma, this being due to its ability

both to fully demonstrate lymphatic drainage

patterns and to permit the accurate pre-operative

localisation of all sentinel nodes visualised. Knowl-

edge of these lymphatic drainage patterns has

been found to predict difficulties in identifying the

sentinel node and to assist in the prevention of

false-negative biopsies in breast cancer by the

incorrect interpretation of tracer uptake in mul-

chapter