P. Bianchi et al., Different sites and modes of tracer injection for mapping the sentinel lymph node in patients with breast cancer, TUMORI, 86(4), 2000, pp. 307-308
Several studies have been published describing the techniques of identifica
tion of the "sentinel lymph node" (SN), There are marked differences In the
techniques used by different investigators. Although agreement exists abou
t the tracer particle size and the volume of injection, it is unknown what
is the best site where to inject the tracer or the vital dye. The aim of th
e present study was to define the influence of different sites of injection
on Imaging of the lymphatic ducts and their SNs, We performed a pilot stud
y in 30 consecutive patients with breast cancer who underwent SN biopsy by
means of radioguided surgery and vital blue dye mapping. The patients were
divided Into six groups of five patients each; each patient was given a sub
dermal (ID) or peritumoral (IP) injection of radiotracer (300 mu Ci in 150
mL of Tc-99m-HSA microcolloids; Albures, Amersham Sorin) above the tumor si
te in order to localize the SN. After the identification of the SN, a secon
d injection of radiotracer was performed, which was different in each patie
nt subset. In some cases more than one lymph node appeared on the lymphosci
ntigraphic scans after the second injection of radiotracer.
When the peritumoral route was used it took longer to visualize the lymphat
ic pathways. For the ID route, injection at the exact skin projection over
the tumor is optimal. Internal mammary lymph nodes were identified by both
IP (2) end ID (1) injection, irrespective of the quadrant in which the trac
er was injected.
Our findings support the hypothesis of a precise topographic correspondence
between the primary tumor and its specific SN. The subdermal route is more
accurate than the intraparenchymal route, as it allows faster identificati
on of the lymphatic vessels and SN, We believe these observations should be
taken into account for the proper selection of the injection site of eithe
r vital dye or radiopharmaceuticals.