Image of tumor metastasis and inflammatory lymph node enlargement by contrast-enhanced ultrasonography.
OBJECTIVE
To compare the difference between tumor-induced lymph node enlargement and inflammation-induced lymph node enlargement by contrast-enhanced ultrasonography and pathological findings.


METHODS
A model of tumor-induced lymph node metastasis was prepared by embedding a VX2 tumor into the hind paws of white rabbits. A model of inflammation-induced enlargement was prepared by injecting a suspension of Escherichia coli into separate hind paws of white rabbits. Then, a solution of Sonazoid™ (GE Healthcare, Oslo, Norway) was injected subcutaneously in the proximity of the lesion followed by contrast-enhanced ultrasonography of the enlarged popliteal lymph nodes.


RESULTS
In the contrast-enhanced ultrasonography of the tumor-induced metastasis model, the sentinel lymph node was imaged. An area of filling defect was observed in that enlarged lymph node. In the histology examination, the area of filling defect corresponded to the metastatic lesion of the tumor. Contrast-enhanced ultrasonography of the model on inflammation-induced lymph node enlargement, and that of the acute inflammation model performed 3-7 d later, revealed dense staining that was comparatively uniform. The pathological findings showed acute lymphadenitis mainly due to infiltration of inflammatory cells. Contrast-enhanced ultrasonography that was performed 28 d post-infection in the acute inflammation model showed speckled staining. Inflammation-induced cell infiltration and fiberization, which are findings of chronic lymphadenitis, were seen in the pathological findings.


CONCLUSIONS
Sentinel lymph node imaging was made possible by subcutaneous injection of Sonazoid™. Contrast-enhanced ultrasonography was suggested to be useful in differentiating tumor-induced enlargement and inflammation-induced enlargement of lymph nodes.
Takaya Aoki, Fuminori Moriyasu, Kei Yamamoto, Masafumi Shimizu, Masahiko Yamada, Yasuharu Imai, Department of Gastroenterology and Hepatology, Tokyo Medical University, 6-7-1, Nishishinjuku, Shinjyuku-ku, Tokyo 160-0023, Japan.
Takaya
T
Aoki
Fuminori
F
Moriyasu
Kei
K
Yamamoto
Masafumi
M
Shimizu
Masahiko
M
Yamada
Yasuharu
Y
Imai