Barry B. Goldberg MD, Presenter: Nothing to Disclose

Daniel Arthur Merton, Abstract Co-Author: Nothing to Disclose

Ji-Bin Liu MD, Abstract Co-Author: Research grant, Hospira, Inc

Adam Berger MD, Abstract Co-Author: Nothing to Disclose

Agnieszka Witkiewicz MD, Abstract Co-Author: Nothing to Disclose

John Robery Eisenbrey PhD, Abstract Co-Author: Nothing to Disclose

Flemming Forsberg PhD, Abstract Co-Author: Equipment support, Toshiba Corporation Equipment support, Siemens AG Research collaboration, General Electric Company Research collaboration, Ultrasonix Medical Corporation Research collaboration, Toshiba Corporation Advisory Board, Siemens AG Advisory Board, Toshiba Corporation

To determine if CEUS can be used to localize secondary lymph nodes (2LNs) in swine with naturally-occurring melanoma and to compare the detection of metastases in 2LNs identified by CEUS to lymph nodes (LNs) removed by radical resection.

Twenty-one swine received peritumoral injections (dose 1.0 ml) of Sonazoid (GE Healthcare, Oslo, Norway) to enhance sentinel lymph nodes (SLNs). Sonazoid was then injected under US guidance into the enhanced SLNs (dose 0.2-0.5 ml) to detect contrast-enhanced efferent lymphatic channels and 2LNs. After peritumoral blue dye injections, a radical LN resection was performed by a surgeon blinded to the CEUS results. The surgeon removed all dye-stained LNs and other LNs he considered 2LNs. Each 2LN identified by CEUS or LN removed by the surgeon was assessed by pathology (the reference standard for the presence of metastases). The benefit of CEUS-directed 2LN resection over radical LN resection was calculated by a clustered conditional logistic regression analysis of correlated proportions. An odds ratio (OR) for correct detection of 2LNs was calculated (i.e., malignant LNs detected and benign LNs not detected were counted as a correct result for a given technique). A 2-sided McNemar’s test was used to compare the number of 2LNs identified by CEUS that had metastases to LNs removed by radical resection on per-swine and per-LN bases.

Metastases in the 2LNs was detected in 16 of 21 swine (76.2%). One hundred ninety-four LNs were resected, of which 35 (18%) were positive for metastases. Thirty-three of 186 (17.7%) LNs identified by the surgeon had metastases compared to 23 of 63 (36.5%) 2LNs identified by CEUS. Two LNs identified by CEUS were over 6-times more likely to have metastases than LNs identified by surgery (OR= 6.3; p<0.001). The number of swine diagnosed correctly as having 2LN metastases based on CEUS compared to surgery was not significant, but on a per 2LN basis CEUS was significantly better than surgery (p<0.0001).

Preliminary results demonstrate that 2LNs can be detected following direct injection of Sonazoid into SLNs. 2LNs identified by CEUS are significantly more likely to contain metastases than those removed by radical surgical resection.

CEUS has the potential to improve 2LN resection by reducing the degree of sugical exploration compared to the currently utilized radical LN resection approach.

Goldberg, B, Merton, D, Liu, J, Berger, A, Witkiewicz, A, Eisenbrey, J, Forsberg, F, Contrast-enhanced Ultrasound Imaging (CEUS) Detection of Secondary Lymph Nodes Compared to Radical Lymph Node Resection.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11015778.html