Fast magnetic resonance imaging techniques for guiding coronary interventions

The use of magnetic resonance (MR) imaging for guiding coronary interventions is in its infancy. For MR guided coronary interventions to be feasible, a fluoroscopy-type sequence technology should be available that allows near real-time demonstration of all manipulations performed with high spatial resolution in order to reduce the risks of the intervention. In this work, we proposed several fast magnetic resonance imaging techniques that could be applied for guiding coronary interventions.; One of the unique features of MRI in guiding interventions is the ability to collect oblique three dimensional (3D) or multislice images. Since full 3D imaging is slow, we proposed an acquisition scheme termed V&barbelow;olumetric I&barbelow;maging with in&barbelow;terleaved A&barbelow;cquisition of intra-o&barbelow;blique S&barbelow;lices (VINAOS) which collects temporally and spatially matched composing planes for dynamic imaging of an area of interest. This approach interleaves the collected individual slices in order to acquire the same k-space segments of all slices during almost the same time window to minimize or even eliminate the spatial mismatch error of the depicted structures.; Visualization of a specific segment or a branch of a vessel maybe sufficient for certain situations, such as guiding a vascular intervention with MRI. With contrast enhanced vessels and suitable background suppression, STAKSE (S&barbelow;tructure T&barbelow;argeting k&barbelow; s&barbelow;pace Selection) was developed to selectively collect the augmented keyhole k-space that corresponds to this segment or branch of the vessel. That way, high spatial and high temporal resolution can be achieved together with limited blurring of the targeted portion of the vessel.; Projection MR Angiography (MRA) of contrast enhanced (CE) coronary vessels, with intra-arterial (IA) infusion of T1-shortening Gd based agents, has been used for fast coronary MRA. For improved vessel contrast-to-noise (CNR), magnetization driven preparation sequences using a Saturation followed by Multiple Inversion Recoveries (SMIR) have shown good background suppression. To reduce the duration of the SMIR preparation to less than 200 ms, an objective function optimization method was implemented on SMIR schemes to optimize the intra-pulse delays according to the number of preparation pulses. The optimized preparation schemes were validated with phantom studies and evaluated for fast imaging of the coronary arteries during intra-arterial infusion of MR contrast agent.; In conclusion, the proposed dynamic volume imaging with interleaved acquisition of intra-oblique slices, fast MR angiography with structure targeting k-space selection, and magnetization driven preparation technique with optimized saturation and multiple inversion recoveries could be applied for guiding coronary interventions.