The status of blood vessel walls plays a central roll in cardiovascular physiology. However, standard MR scanning techniques, such as magnetic resonance angiography (MRA) generally provide information about the content of the blood vessels – the blood – but not the tissue itself. Recently we introduced a novel spectroscopic MRI method for displaying distinct tissue layers of large blood vessel wall as well as measuring their mechanical strain. The method is based on the observation of the deuterium double-quantum-filtered (DQF) NMR signal, which is indicative for the presence of motional anisotropy of water in the tissue. We have found that 2H DQF NMR spectral line shapes of water molecules inside large blood vessel walls are highly sensitive to the composition of tissue layers as well as the strain exerted on the vessel wall.
MRI of deuterium nuclei suffers from low sensitivity due to their low gyromagnetic ratio and low concentrations in biological tissues. Thus, the advantage of the 1H nucleus for in vivo NMR applications is apparent. Residual dipolar interaction between two protons can also give rise to DQF NMR signals. We propose to apply the 1HDQF spectroscopic technique to imaging of blood vessel walls and create a new contrast based on the degree of order in the tissue. By adjusting the parameters of the DQF imaging pulse sequence, one can modify the contrast and enhance the images of specific compartments within the organ. Research so far indicates that while imaging pulse sequence and its parameters have not yet been optimized, DQF MRI may enable better assessment of abnormalities and injuries in blood vessel walls and monitoring of their recovery.
