NMR imaging of changes in vascular morphology due to tumor angiogenesis

✍ Scribed by Joelle Dennie; Joseph B. Mandeville; Jerrold L. Boxerman; Scott D. Packard; Bruce R. Rosen; Robert M. Weisskoff

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 778 KB
• Volume: 40
• Category: Article
• ISSN: 0740-3194
• DOI: 10.1002/mrm.1910400602

✦ Synopsis

Abstract

Tumor‐sprouted vessels are greater in both number and diameter in comparison to their healthy counterparts. A novel technique based on magnetic susceptibility contrast mechanisms that are sensitive to varying sizes of blood vessels is presented to measure differences between the relaxation rates (1/T~2~ and 1/T) in a rat glioma model and normal cerebral cortex. ΔR2 and ΔR2*, the differences between relaxation rates precontrast and postcontrast agent injection, were measured for an intravascular equilibrium contrast agent (MION) at various echo times. Since ΔR2*/ΔR2 increases as vessel size increases, this ratio can be used as a measure of the average vessel size within an ROI or a voxel. The stability and longevity of the contrast agent within the vasculature were verified (n = 2 trials), and the ratio of ΔR2*/ΔR2 between the tumor and normal cortex was measured to be 1.9 ± 0.2 (n = 4, echo time = 20 ms, and susceptibility difference (Δχ) ≈︁ 10^−6^). This ratio compared favorably to a predicted ratio determined using histologically determined vessel sizes and theoretical Monte Carlo modeling results (1.9 ± 0.1). Maps of the ratio of ΔR2*/ΔR2 were also made on a pixel‐by‐pixel basis. These techniques support the hypothesis that susceptibility contrast MRI can provide useful quantitative metrics of in vivo tumor vascular morphology.