Detection and Characterization of Sentinel Lymph Node by Ultrasound Molecular Imaging with B7-H3-Targeted Microbubbles in Orthotopic Breast Cancer Model in Mice

Mol Imaging Biol. 2022 Apr;24(2):333-340. doi: 10.1007/s11307-021-01680-3. Epub 2021 Nov 17.

Abstract

Purpose: Accurate identification and assessment of sentinel lymph node (SLN) using noninvasive imaging methods can play a vital role in tumor staging, surgical planning, and prognostic evaluation. In this study, we assessed the efficacy of B7-H3-targeted molecular-ultrasound imaging for the early SLN detection, and characterization in a mouse model of orthotopic breast cancer.

Procedures: We established a mouse breast cancer model with lymph node metastasis by injecting MAD-MB 231 cells which were engineered to express firefly luciferase reporter gene into the fat pad of the right 4th mammary gland in female BALB/c nude mice. The sole lymph node (LN) close to the tumor was regarded as the SLN for imaging investigation, which included metastatic and non-metastatic SLNs. The LN in the right 4th mammary gland from normal mice was used as normal control (normal mice LN). The commercially available preclinical streptavidin-coated, perfluorocarbon-containing lipid-shelled microbubbles (VisualSonics, Toronto, Canada) were used to generate B7-H3-targeted microbubbles (MBB7-H3) and control microbubbles (MBControl). Then, ultrasound molecular imaging (USMI) was performed using a high-resolution transducer (MS250; center frequency, 21 MHz; Vevo 2100; VisualSonics, Toronto, Canada) after intravenous injection of microbubbles.

Results: The SLN was clearly detected and located under conventional (B-mode) and contrast-enhanced ultrasonography with microbubble injection. The metastatic SLNs showed a markedly higher signal from B7-H3-targeted microbubbles (MBB7-H3) compared to the non-metastatic SLNs and normal LNs. The metastatic SLN was further confirmed by ex vivo bioluminescence imaging and eventually verified by histological analysis.

Conclusions: Our findings suggest the potential value of USMI using B7-H3 targeted microbubbles in breast cancer and establish an effective imaging method for the non-invasive detection and characterization of SLN.

Keywords: B7-H3; Breast cancer; Microbubbles; Molecular imaging; Sentinel lymph node; Ultrasound.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Breast Neoplasms* / diagnostic imaging
  • Breast Neoplasms* / pathology
  • Contrast Media / chemistry
  • Female
  • Humans
  • Lymph Nodes / diagnostic imaging
  • Lymph Nodes / pathology
  • Mice
  • Mice, Nude
  • Microbubbles
  • Molecular Imaging / methods
  • Sentinel Lymph Node Biopsy / methods
  • Sentinel Lymph Node* / diagnostic imaging
  • Sentinel Lymph Node* / pathology
  • Ultrasonography / methods

Substances

  • Contrast Media