Model to quantify lymph node enhancement on indirect sonographic lymphography.
OBJECTIVE
Our goal was to develop a reliable technique that has minimal operator dependence for quantifying lymph node enhancement to test and optimize new sonography contrast formulations.


METHODS
Twenty healthy rabbits were studied using five agents, labeled A-G. Agents D and E were the same agent and agents F and G were Imagent, studied blindly to test reproducibility. One milliliter of contrast agent was injected into each hind footpad. A 13-MHz transducer was fixed over the popliteal node, which was imaged at a 4.8-MHz central transmit frequency using phase-inversion technology at 100% power and one frame per second. Immediately after each injection, the footpad was massaged 12 times for 30 sec each time and then imaged after each massage to assess the number of times the node could be refilled from each injection. Lymph node video intensity was measured, and the degree of enhancement was evaluated using analysis of variance with the massage number and the agent used as independent variables.


RESULTS
Lymph node enhancement was observed after the first massage with all agents. Degree of enhancement was least with agents A and B, intermediate with agents D and F, and greatest with agent C. Agent A was effective after the first two massages, agent B after the first four, agent C after all 12, agent D after the first eight, and agent F after the first nine. Performance of agents D and F was similar to that of their duplicates, E and G.


CONCLUSIONS
We established a reproducible technique to quantify lymph node enhancement that can distinguish between different agents. The differences in performance suggest that it is possible to optimize agent formulation for indirect sonographic lymphography.
Department of Radiology, University of California, San Diego, 200 W Arbor Dr., San Diego, CA 92103, USA.
Sang-Hee
SH
Choi
Yuko
Y
Kono
Jacqueline
J
Corbeil
Olivier
O
Lucidarme
Robert F
RF
Mattrey
D000704:Analysis of Variance; D000818:Animals; D003287:Contrast Media / Q000008:administration & dosage*; D005260:Female; D008198:Lymph Nodes / Q000000981:diagnostic imaging*; D011817:Rabbits; D015203:Reproducibility of Results; D014463:Ultrasonography
D003287:Contrast Media