Vessel size imaging using dual contrast agent injections.

Area of Science:

• Neuroimaging
• Medical Physics
• Oncology

Background:

• Accurate assessment of tumor vascularity is crucial for diagnosis and treatment planning.
• Microvascular changes, including caliber, are key indicators of tumor biology.
• Existing imaging techniques may have limitations in precisely quantifying microvessel size.

Purpose of the Study:

• To evaluate the feasibility of a novel vessel size imaging (VSI) technique using separate contrast agent injections.
• To assess the accuracy of VSI for measuring vessel caliber in normal brain tissues and brain tumors.

Main Methods:

• Computer simulations were conducted to determine potential errors from time shifts between dual contrast injections.
• Dynamic susceptibility contrast MRI with gradient echo (GE) and spin echo (SE) sequences was performed on eight brain tumor patients.
• Vessel caliber maps were generated and analyzed in regions of interest, including gray matter, white matter, thalamus, and tumors.

Main Results:

• Computer simulations indicated less than 5% error in vessel caliber estimation with a 1-second time shift between injections.
• VSI accurately measured vessel calibers in normal tissues (GM: 37.4±12.9 µm, thalamus: 20.7±8.8 µm, WM: 15.0±5.1 µm).
• All brain tumors exhibited significantly larger mean vessel diameters compared to normal-appearing tissues.

Conclusions:

• Vessel size imaging (VSI) with a dual contrast injection method is a feasible technique for clinical application.
• This VSI approach enables reliable estimation of microvascular calibers in both normal brain structures and tumors.
• The technique clearly demonstrates differences in vascular size between normal tissue and brain tumors.