Chemical exchange saturation transfer effect in blood.

Purpose: In this report, the feasibility of using blood as an agent for Chemical Exchange Saturation Transfer (CEST) effect is investigated.

Methods: The CEST effect of porcine blood samples was investigated on a 3.0 T MRI scanner using various power levels and on a 14.1 T NMR spectrometer. As a proof-of-concept that CEST can be used to image blood in vivo, the technique was applied in two locations of healthy human volunteers, namely, the femoral artery and the M1-segment of the middle cerebral artery.

Results: The blood sample experiments showed that maximum CEST Magnetization Transfer Ratio asymmetry (MTRasym) values of ∼ 12% were achieved, with likely contributions from multiple blood components. These findings were confirmed during the in vivo experiments where CEST signal of blood was clearly greater than surrounding muscular (2%) and brain tissue (3%).

Conclusion: Ex vivo and in vivo results show that blood is a suitable CEST agent that generates sufficient CEST contrast relative to surrounding tissue.