Assessing tumor angiogenesis using macromolecular MR imaging contrast media

Area of Science:

• Oncology
• Radiology
• Biomedical Engineering

Background:

• Macromolecular contrast medium (MMCM)-enhanced MRI estimates tumor microvascular characteristics, correlating with histologic microvascular density.
• Vascular endothelial growth factor (VEGF) is a key stimulator of angiogenesis.
• MMCM-enhanced MRI can assess the acute effects of anti-VEGF therapy on tumor vasculature.

Purpose of the Study:

• To investigate the acute tumor microvascular effects of antibody-mediated inhibition of VEGF using MMCM-enhanced MRI.
• To quantify changes in tumor microvascular permeability and blood volume following anti-VEGF treatment.

Main Methods:

• Athymic rats with human breast carcinoma xenografts were imaged using MMCM-enhanced MRI (albumin-Gd-DTPA30).
• Imaging was performed before and 24 hours after a single dose of anti-VEGF antibody.
• A bidirectional two-compartment kinetic model analyzed changes in longitudinal relaxivity (ΔR1) to estimate fractional blood volume (fBV) and permeability-surface area product (PS).

Main Results:

• A significant decrease in tumor PS was observed 24 hours post-anti-VEGF antibody treatment (P < 0.05).
• No significant change in tumor fractional blood volume (fBV) was detected.
• MMCM-enhanced MRI successfully detected and quantified the suppression of tumor microvascular permeability induced by anti-VEGF antibody.

Conclusions:

• MMCM-enhanced MRI can effectively monitor the anti-angiogenic effects of VEGF inhibition by quantifying changes in tumor microvascular permeability.
• This MRI technique holds promise for clinical applications in grading tumor angiogenesis and monitoring anti-angiogenesis interventions.