Magnetic resonance (MR) active invasive devices for the generation of selective MR angiograms

摘要

A magnetic resonance (MR) active invasive device system employs a radio-frequency (RF) coil embedded in an invasive device for the purpose of generating MR angiograms of a selected blood vessels. A subject is first placed in a polarizing magnetic field. The invasive device is then placed into a selected blood vessel of the subject such that the RF coil of the invasive device is located at or near the root of a vessel tree desired to be imaged. The RF coil is then used to alter the nuclear spin magnetization of blood flowing within the vessel. This is done by employing an RF excitation signal to the coil at the Larmor frequency of the blood. The nutation of spin magnetization can change the amount of longitudinal spin magnetization or the Amount of magnetization in the transverse plane. Because the size of the radio-frequency coil in the invasive device is small, the change in spin magnetization is limited to blood flowing by the invasive device. An MR imaging pulse sequence is then applied to the subject to obtain image information from the region containing the desired vessel tree. The MR imaging pulse sequence is designed to selectively detect the blood whose spin magnetization has been changed by the MR-active invasive device. Since only blood which the magnetization has modified is detected with the imaging sequence, the vessel tree is imaged.