210 results about "Surface coil" patented technology

A system and method for using magnetic resonance imaging to increase the accuracy of electrophysiologic procedures is disclosed. The system in its preferred embodiment provides an invasive combined electrophysiology and imaging antenna catheter which includes an RF antenna for receiving magnetic resonance signals and diagnostic electrodes for receiving electrical potentials. The combined electrophysiology and imaging antenna catheter is used in combination with a magnetic resonance imaging scanner to guide and provide visualization during electrophysiologic diagnostic or therapeutic procedures. The invention is particularly applicable to catheter ablation, e.g., ablation of atrial fibrillation. In embodiments which are useful for catheter ablation, the combined electrophysiology and imaging antenna catheter may further include an ablation tip, and such embodiment may be used as an intracardiac device to both deliver energy to selected areas of tissue and visualize the resulting ablation lesions, thereby greatly simplifying production of continuous linear lesions. The invention further includes embodiments useful for guiding electrophysiologic diagnostic and therapeutic procedures other than ablation. Imaging of ablation lesions may be further enhanced by use of MR contrast agents. The antenna utilized in the combined electrophysiology and imaging catheter for receiving MR signals is preferably of the coaxial or “loopless” type. High-resolution images from the antenna may be combined with low-resolution images from surface coils of the MR scanner to produce a composite image. The invention further provides a system for eliminating the pickup of RF energy in which intracardiac wires are detuned by filtering so that they become very inefficient antennas. An RF filtering system is provided for suppressing the MR imaging signal while not attenuating the RF ablative current. Steering means may be provided for steering the invasive catheter under MR guidance. Other ablative methods can be used such as laser, ultrasound, and low temperatures.

An RF coil assembly for use in a multiple receive-channel MRI system is provided. The RF coil assembly is configured as a multi-turn-element RF coil assembly to operate as a surface-coil array in cooperation with the MRI system which is configured to operate in a multiple-channel receive mode.

A magnetic resonance imaging method employs sub-sampled signal acquisition from a number of receiver coils such as surface coils. A full field-of-view magnetic resonance image is reconstructed on the basis of the sensitivity profiles of the receiver coils, for example on the basis of the SENSE technique. The reconstruction is carried out mathematically as an optimization, for example, requiring a minimum noise level in the magnetic resonance image. According to the invention, a priori information is also involved in the reconstruction and the a priori information is taken into account especially as a constraint in optimization.

An RF coil having at least three different resonance frequencies, wherein one of the resonance frequencies is adjusted to be a frequency fA of a magnetic resonance signal generated by a test subject, and the coil is adjusted so that ratio of difference between the frequency fA and a first frequency fB lower than fA and nearest to fA among the resonance frequencies (fA−fB), and difference between the frequency fA and a second resonance frequency fC higher than fA and nearest to the frequency fA among the resonance frequencies (fC−fA), should be from 0.5 to 2.0. There is provided a technique for receiving magnetic resonance signals always with high detection efficiency by an RF coil of an MRI apparatus even if significant loss is caused in the RF coil, or test subject is changed.

A method for calculating a sensitivity distribution of a receive coil and taking a tomographic image of a subject, based on magnetic resonance signals received by a surface coil in an imaging sequence with a plurality of different echo times TE1 and TE2 in a reference scan, a plurality of reference images are produced by a first reference image producing section; and based on the plurality of reference images, a T2 relaxation time is calculated by a T2 relaxation time calculating section. Then, based on the calculated T2 relaxation time, a T2-weighted image at the echo time TE2 is calculated by a T2-weighted image calculating section, and thereafter, based on the reference image and T2-weighted image at the echo time TE2, a sensitivity distribution is calculated by a sensitivity distribution calculating section. Based on the sensitivity distribution, a tomographic image by an actual scan is corrected by a correcting section.