Contrast-enhanced sonographic imaging of lymphatic channels and sentinel lymph nodes.
OBJECTIVE
The purpose of this study was to determine whether lymphatic channels (LCs) and sentinel lymph nodes (SLNs) could be detected on sonographic imaging after subcutaneous, submucosal, or parenchymal injections of a sonographic contrast agent (ie, lymphosonography) in a variety of anatomic locations in several animal models.


METHODS
Eight swine, 7 canines, 4 rabbits, and a monkey were used for these evaluations. Gray scale pulse inversion harmonic imaging of the LCs and the SLNs was performed after subcutaneous (n = 58), submucosal (n = 14), or parenchymal (n = 8) injections of a tissue-specific sonographic contrast agent (Sonazoid; GE Healthcare, Oslo, Norway). In many instances, blue dye was injected into the same locations as Sonazoid, and surgical dissection of the SLNs and LCs was performed for comparison. Scanning electron microscopy (SEM) of contrast-enhanced and control lymph nodes from 2 rabbits was performed to determine the mechanism of contrast agent uptake and retention within SLNs.


RESULTS
After subcutaneous, submucosal, or parenchymal contrast agent injections, gray scale pulse inversion harmonic imaging could be used to identify the number and location(s) of LCs and SLNs. After subcutaneous, submucosal, or parenchymal contrast agent injections, Sonazoid was confined to the SLNs (ie, contrast enhancement was not detected in the second-echelon nodes). There was good agreement between the results of lymphosonography and blue dye with surgical dissection in identifying the regional LCs and SLNs. Scanning electron microscopy identified vacuoles representing intact contrast microbubbles within contrast-enhanced SLN macrophages, which were not present in the control lymph nodes.


CONCLUSIONS
Lymphosonography can be used to detect lymphatic drainage pathways and SLNs in a variety of animal models.
The Jefferson Ultrasound Research and Education Institute, Department of Radiology, Thomas Jefferson University Hospital, Philadelphia, PA 19107, USA.
Barry B
BB
Goldberg
Daniel A
DA
Merton
Ji-Bin
JB
Liu
George
G
Murphy
Flemming
F
Forsberg
D000005:Abdomen / Q000000981:diagnostic imaging; D000818:Animals; D003287:Contrast Media / Q000008:administration & dosage* / Q000493:pharmacokinetics; D004285:Dogs; D005290:Ferric Compounds / Q000008:administration & dosage* / Q000493:pharmacokinetics; D041981:Gastrointestinal Tract / Q000000981:diagnostic imaging; D000882:Haplorhini; D007089:Image Enhancement / Q000379:methods*; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D007267:Injections / Q000379:methods; D007279:Injections, Subcutaneous / Q000379:methods; D007501:Iron / Q000008:administration & dosage* / Q000493:pharmacokinetics; D008197:Lymph Node Excision / Q000379:methods; D008198:Lymph Nodes / Q000000981:diagnostic imaging* / Q000601:surgery; D042601:Lymphatic Vessels / Q000000981:diagnostic imaging* / Q000601:surgery; D008297:Male; D008855:Microscopy, Electron, Scanning / Q000379:methods; D023421:Models, Animal; D010087:Oxides / Q000008:administration & dosage* / Q000493:pharmacokinetics; D011467:Prostate / Q000000981:diagnostic imaging; D011817:Rabbits; D021701:Sentinel Lymph Node Biopsy / Q000379:methods; D013552:Swine; D013737:Testis / Q000000981:diagnostic imaging; D018615:Ultrasonography, Doppler, Color / Q000379:methods
D003287:Contrast Media; D005290:Ferric Compounds; D010087:Oxides; C069727:Sonazoid; D007501:Iron