Interstitial MR lymphangiography for the detection of sentinel lymph nodes.
OBJECTIVE
The challenge for implementation of sentinel lymph node biopsy is to develop a reliable minimally invasive technique that identifies all possible sentinel nodes with high temporal and spatial resolution. This study evaluated the use of a magnetic resonance imaging (MRI) contrast agent (USPIO) for preoperative sentinel node detection.


METHODS
Anesthetized pigs received interstitial or intradermal injections of ultra small superparamagnetic of iron oxide (USPIO) (0.2 or 5 mg Fe) in the L/R posterior tongue and stifles (knee) respectively. MRI was done before, during injection and at 0.25, 0.5, 1, 2, 4, 6, 24, and 48 hr after which isosulfan blue sentinel node mapping was done.


RESULTS
In the tongue, both doses of USPIO identified the sentinel node in the early images. No additional nodes were detected by MR at 24 or 48 hr. In the hind limb, sentinel nodes identified on the early MR images were also identified by the isosulfan blue. In both locations, the higher dose also identified secondary nodes some of which were also identified by the isosulfan blue. All sentinel nodes that were identified by USPIO on MRI were noted to be stained brown at the time of dissection.


CONCLUSIONS
Interstitial MR lymphangiography is a useful technique for the detection of sentinel lymph nodes. This method provides excellent simultaneous temporal and spatial resolution, is minimally invasive, and can be performed preoperatively.
Torchia
M G
MG
Department of Surgery, The University of Manitoba, Winnipeg, Manitoba, Canada. Mark_Torchia@sbrc.mb.ca
Nason
R
R
Danzinger
R
R
Lewis
J M
JM
Thliveris
J A
JA
D000818:Animals; D005260:Female; D008198:Lymph Nodes / Q000473:pathology* / Q000648:ultrastructure; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008854:Microscopy, Electron; D012394:Rosaniline Dyes; D021701:Sentinel Lymph Node Biopsy; D013552:Swine
D012394:Rosaniline Dyes; C025484:iso-sulfan blue