Abstract: The invention is an MRI imaging system that seamlessly switches between a fast imaging fluoro-mode and a diagnostic imaging mode. The fluoro-mode is used to quickly obtain an image which provides confirmation that the selection of MR imaging parameters are proper and to provide an opportunity to adjust these selections. After the selections have been confirmed and adjusted, the system is switched to a normal diagnostic image mode using the parameter selects as modified during fluoro-mode imaging.

Abstract: Continuously updated real-time magnetic resonance imaging processes are used to display an MR image volume to an operator and/or patient co-located with the MRI magnet, viewing console and other elements of an MRI system within the same shielded gantry room. A CRT display may be used for lower field MRI systems while liquid crystal displays may be necessary for higher field MRI systems since the viewing console is to be co-located within the shielded gantry room near the MRI magnet assembly. Suitable RF shielding is provided to RF-isolate the viewing console and its related power and video signal cables from the MRI RF coils being used to monitor relatively weak NMR signals emanating from the image volume within the magnet assembly.

Abstract: Positioning of interventional devices within the patient image volume of an MRI system is performed while viewing real-time fluoroscopic MR images of such devices superimposed upon a saved prior image ("ghost") of patient anatomy that was earlier located within the same image volume. After such interventional medical procedure is thoroughly planned using the earlier acquired three-dimensional ghost image, the patient anatomy is relocated within the image volume and the final selected trajectory for the interventional device or medical procedure is then performed (preferably while real time MRI fluoroscopy is used to monitor the actual interventional procedure within the real patient anatomy).

Abstract: In a phase encoded chemical shift imaging (CSI) system, phase shifting in k space is used to shift voxels so as to translate them in one or more dimensions so that one or more voxels maximally encloses an object of interest. The position of a structure of interest is located via a 1H "scout" image, and the Shift Theorem for finite Fourier transforms is applied to shift voxel boundaries in one, two or three dimensions so as to maximally enclose the structure in a minimal number of voxels. Voxel shifts thus may be accomplished computationally by minimal manipulation of the raw data--after the patient has left the imaging facility. The resulting spectral data corresponding to the structure of interest is not as subject to dilution by spectrum of the surrounding tissue.

Abstract: An automated magnetic field shimming process for magnetic resonance spectroscopic imaging (MRSI) uses doubly phase encoded NMR spin echo responses in conjunction with multiple fourier transformation to derive a spectroscopic plot for each voxel in a three-dimensional array of voxels in an image volume (including portions of a living subject) which is to be subsequently subjected to MRSI using NMR FID or spin echo responses. The thus derived hydrogen peak frequency is taken as a measurement of existing static magnetic field intensity within that voxel and adjusted shim coil currents are calculated so as to reduce or minimize nonuniformity of the static magnetic field. A nonexistent pseudo shim coil having an assumed uniform shim contribution may enhance the resulting field homogeneity. The auto shimming procedure may be applied iteratively as required to achieve the predetermined degree of field uniformity.