Abstract: A radio-frequency coil (RF-coil) (19) for use in a magnetic-resonance imaging apparatus comprises a number of parallel bar-shaped electric conductors (37) arranged at regular intervals on an imaginary cylinder (39) and surrounded by a radio-frequency shield (RF-shield) (49). The bar-shaped conductors surround a measuring volume (11) and are interconnected at least at one of their end portions (41, 45) by an electric end conductor (43, 47) extending in a plane transverse to the bar-shaped conductors. A further electric end conductor (51, 53) is arranged near and parallel to the end conductor (43, 47), and is electrically connected to the RF-shield (49), preferably by a flange-shaped electric conductor (55, 57). The end conductor (43, 47) and the further end conductor (51, 53) together form a transmission line.

Abstract: A magnetic resonance imaging (“MRI”) system and method of correcting for the motion of a subject during an MRI scan. The motion of a subject in an MRI scan is corrected by acquiring nuclear magnetic resonance (“NMR”) spectra of an ordered material attached to a subject, wherein there is a dependence on the NMR spectra of the ordered material's orientation in a magnetic field, and determining an orientation of the subject. Correction information is then supplied to a primary spectrometer channel which is used to execute an MRI scan, and an imaging pulse sequence of the MRI scan is adjusted to correct the subject's orientation.

Abstract: A method of operating a magnetic resonance imaging system having a first coil and a second coil to achieve an imaging volume includes, in a first mode, achieving the imaging volume by using a sum field from both of the coils, and, in a second mode, achieving the imaging volume by using a difference field from both of the coils.

Abstract: A magnetic resonance imaging apparatus acquires magnetic resonance signals by the PI method using an RF coil unit having basic coils serving as surface coils which are arrayed with at least two coils along a static magnetic field direction (z direction) and at least two coils along each of two orthogonal x, y directions. The coils are divided into an upper unit and a lower unit. The upper unit and lower unit are fixed by a band or the like to allow them to be mounted on an object to be examined. The signals detected by the respective surface coils are sent to a data processing system through independent receiver units and formed into a magnetic resonance image.

Abstract: Nuclear magnetic resonance (NMR) signals are detected in microtesla fields. Prepolarization in millitesla fields is followed by detection with an untuned de superconducting quantum interference device (SQUID) magnetometer. Because the sensitivity of the SQUID is frequency independent, both signal-to-noise ratio (SNR) and spectral resolution are enhanced by detecting the NMR signal in extremely low magnetic fields, where the NMR lines become very narrow even for grossly inhomogeneous measurement fields. MRI in ultralow magnetic field is based on the NMR at ultralow fields. Gradient magnetic fields are applied, and images are constructed from the detected NMR signals.

Abstract: A restraining apparatus and method for limiting motion on the macro and micro scale during MRI and CT scans, by providing a custom fit, while also improving patient comfort. The restraining apparatus includes a disposable component, including castable and expandable sleeves used to fix the patient into a coil. The castable sleeve encircles the limb of a patient, and is filled with a quickly casting material. The cast material is patient compatible and preferably designed to augment imaging. The resulting cast is MRI compatible, safe and rapid setting, which will decrease the time to set up a patient for scanning, thereby further improving MRI productivity. The expandable sleeve encircles the castable sleeve and is inflatable such that the expandable sleeve conforms to the inner dimensions of a particular MRI coil, CT scanner, or other imaging device. Alternatively, the apparatus includes a castable sleeve for casting around a flex/wrap or surface coil.

Abstract: A system for combining electromagnetic position and orientation tracking with magnetic resonance scanner is provided. One embodiment includes a magnetic resonance scanner defining a reference coordinate system for scanning a target. Coupled to the magnetic resonance scanner is a magnetic field source which produces a magnetic field. The magnetic field is sensed by a magnetic field sensor which produces a signal proportional to the magnetic field. The magnetic field sensor has a location relative to the reference coordinate system. The location of the magnetic field sensor relative to the reference coordinate system of the magnetic resonance scanner is determined by a location tracking device using at least a line segment model of the magnetic field source and the signal from the magnetic field sensor.

Abstract: A magnetic resonance imaging apparatus is provided for collecting magnetic resonance signals while applying a static magnetic field, a gradient magnetic field and an RF magnetic field to a subject to be imaged, and producing an image based on the magnetic resonance signals, the apparatus comprising: an RF coil for conducting at least one of the application of the RF magnetic field and reception of the magnetic resonance signals, in which RF coil, ratios of the electric currents flowing through a plurality of coil elements connected in parallel are adjusted by adjusting device.

Abstract: A local radio-frequency antenna for a magnetic resonance apparatus is fashioned for a region to be imaged in an edge region of and/or outside an imaging volume of the magnetic resonance apparatus, and the radio-frequency antenna has a passive shim device.

Abstract: The invention relates to an MR imaging method for representing and determining the position of a medical device inserted in an examination object, and to a medical device used in the method. In accordance with the invention, the device (11) comprises at least one passive oscillating circuit with an inductor (2a, 2b) and a capacitor (3a, 3b). The resonance frequency of this circuit substantially corresponds to the resonance frequency of the injected high-frequency radiation from the MR system. In this way, in a locally limited area situated inside or around the device, a modified signal answer is generated which is represented with spatial resolution.

Abstract: The invention relates to a method of imaging a vascular tree that yields additional information concerning the vascular tree. To this end, a sequence of clusters is determined from spatially coherent voxels in the three-dimensional image of the vascular tree, the sequence of said clusters corresponding to the flow direction of the blood or the contrast medium in said vascular tree.

Abstract: An assembly for shielding an implanted medical device from the effects of high-frequency radiation and for emitting magnetic resonance signals during magnetic resonance imaging. The assembly includes an implanted medical device and a magnetic shield comprised of nanomagnetic material disposed between the medical device and the high-frequency radiation. In one embodiment, the magnetic resonance signals are detected by a receiver, which is thus able to locate the implanted medical device within a biological organism.

Abstract: According to one embodiment of the invention, an apparatus for magnetic resonance imaging is provided. The apparatus includes a detection surface defined by a plurality of sensors. Each of the sensors is operable to receive image information concerning a particular portion of a target surface by substantially confining to the each of the sensors magnetic flux associated with the particular portion of the target surface. The detection surface is operable to acquire all image information for generating a magnetic resonance image resembling the target surface by receiving, at the each of the sensors, a single echo signal from the particular portion of the target surface that correspondingly underlies the each of the sensors. The magnetic resonance image has a resolution of at least sixty-four pixels by a number of pixels equal to M. M is an integer.

Abstract: The present invention provides an MFM or MRFM analytical device comprising a micro-dimensional probe that is capable of detecting single proton and single electron spin. Furthermore, it provides an MFM or MRFM device comprising a micro-dimensional probe, that is capable of detecting magnetic structures of size of order one nanometer. In particular, the present invention provides a micro-dimensional probe for an MFM or MRFM device that comprises a CNT cantilever that comprises a nanoscale ferromagnetic material. The CNT cantilever can be attached to an electrode as a component of a microscopic probe which is coupled with an electrical circuit as a component of a device for nanoscale MFM or MRFM micro-dimensional probes. The device comprising the probe and electrical circuit can be incorporated into an existing scanning probe microscope (SPM) apparatus having accommodation for electrical readout.

Abstract: An apparatus enables a patient to be positioned optimally for a scanning procedure during which images are to be obtained of the vasculature of the patient. The apparatus includes a lumbar support, a tray, and a leg support. The lumbar support allows the renal portion of the vasculature to be positioned predominately in a single plane. The tray allows the pelvic and femoral portions of the vasculature to be positioned substantially coplanar with each other and with the renal portion of the vasculature. The leg support allows the lower leg and feet portions of the vasculature to be positioned substantially coplanar with each other and with the pelvic and femoral portions of the vasculature. The substantial coplanar alignment of the portions of the vasculature enables the images thereof to be obtained with a smaller field of view and thus at least one of greater resolution and reduced scanning time.

Abstract: An imaging probe and method and an MRI system utilizing the same are presented. The probe comprises first and second magnetic field sources, and a receiver of NMR signals. The first magnetic field source creates a primary, substantially non-homogeneous, static magnetic field in a region of interest in a medium outside the probe. The second magnetic field source creates an external time-varying magnetic field, which when being applied to the region of the static magnetic field, is capable of exciting nuclei in an extended sub-region of this region and generating the NMR signals.

Abstract: A restraining apparatus and method for limiting motion on the macro and micro scale during MRI and CT scans, by providing a custom fit, while also improving patient comfort. The restraining apparatus includes a disposable component, including castable and expandable sleeves used to fix the patient into a coil. The castable sleeve encircles the limb of a patient, and is filled with a quickly casting material. The cast material is patient compatible and preferably designed to augment imaging. The resulting cast is MRI compatible, safe and rapid setting, which will decrease the time to set up a patient for scanning, thereby further improving MRI productivity. The expandable sleeve encircles the castable sleeve and is inflatable such that the expandable sleeve conforms to the inner dimensions of a particular MRI coil, CT scanner, or other imaging device. Alternatively, the apparatus includes a castable sleeve for casting around a flex/wrap or surface coil.

Abstract: Microcoils can be used in medical devices to enhance RF response signals and to create fields to enhance imaging capability in MRI imaging systems. An improved microcoil design includes a device to be inserted into a patient comprising a solid body having at least one pair of radially opposed microcoils physically associated with the solid body, each microcoil having an outside microcoil diameter of 6 mm or less, individual windings of each microcoil together defining a geometric plane for each microcoil, and the plane of each microcoil being parallel to the plane of another microcoil in the pair of radially opposed microcoils.

Abstract: An improved intracorporeal device such as a guide wire or other guiding member for use within a patient's body that is at least in part visible under magnetic resonance imaging (MRI) but is not detrimentally affected by the imaging is disclosed. The intracorporeal device has a non-conductive proximal core section, an essentially non-magnetic metallic distal core section that is preferably more flexible than the proximal core section, and that has an MRI visible member or coil in the distal section.

Abstract: An enhancer for improving the clarity and resolution of magnetic resonance images of anatomical regions having limited or excess fat content, which consists of layer of plasticized polyvinyl chloride having a thickness of 0.5 cm to 4 cm. In use, said layer may take a variety of forms so long as the layer is placed in between the body of the patient being examined and the receiving coils of the magnetic resonance imaging system.

Abstract: An inherently de-coupled sandwiched solenoidal array coil (SSAC) is disclosed for use in receiving nuclear magnetic resonance (NMR) radio frequency (RF) signals in both horizontal and vertical-field magnetic resonance imaging (MRI) systems. In its most basic configuration, the SSAC comprises two coaxial RF receive coils. The first coil of the array has two solenoidal (or loop) sections that are separated from one another along a common axis. The two sections are electrically connected in series but the conductors in each section are wound in opposite directions so that a current through the coil sets up a magnetic field of opposite polarity in each section. The second coil of the SSAC is disposed (“sandwiched”) between the two separated solenoidal sections of the first coil in a region where the combined opposing magnetic fields cancel to become a null.

Abstract: A local radio-frequency antenna for a magnetic resonance apparatus is fashioned for a region to be imaged in an edge region of and/or outside an imaging volume of the magnetic resonance apparatus, and the radio-frequency antenna has a passive shim device.

Abstract: The invention relates to the administration of dynamic, particulate dispersion systems, e.g. gas-containing diagnostic contrast agents, more particularly to apparatus and a method for the controlled and substantially steady state administration of such gravity segregating dispersions by infusion. Controlled delivery of substantially homogeneous gravity segregating dispersion, e.g. gas-containing contrast agent, may be achieved by an infusion procedure in which the dispersion is delivered from a syringe or other preferably cylinder shaped reservoir, e.g. tubing, which is exposed to a thermal gradient across its body.

Abstract: Microcoil designs are provided that enable unique RF response Field profiles that are particularly useful in MRI imaging procedures, particularly where fields of view outside of the medical device are desirable. These devices are particulatly for use within an organism, the device comprising an element having at least one RF receiver, the coils of said microcoils defining a cross-section that lies in a plane oriented at 0 to 90 (or 0 to 80) degrees to the longest axis of the device. Another way of describing the device is as a device for use in an organism, the device comprising an element having at least one wound microcoil with at least three windings on the microcoil. Each winding has an aspect ratio of greater than one. The aspect ratio of each winding is measured as the ratio of longest to shortest dimension in a cross section situated approximately transverse to the winding axis of the coil windings, the winding axis also being transverse to the longest axis of said device.

Abstract: A self-localizing receive coil system for use with a Magnetic Resonance Imaging (MRI) system comprises at least one surface coil assembly for placement adjacent to a region of interest to be imaged and a plurality of tracking devices attached to the surface coil assembly for use in indicating location and orientation of the surface coil assembly during imaging.

Abstract: A procedure and apparatus are provided which allow rapid positional change in the patient centering in order to facilitate the imaging of blood vessels in a series of different views. This procedure and apparatus can also facilitate the imaging of other tissues of the body at different spatial locations as well. The procedure and apparatus reduce the time required for obtaining the necessary images for a medical imaging examination using a single injection of an MRI or iodinated contrast agent.

Abstract: A coil for receiving and/or transmitting radio-frequency signals for magnetic resonance imaging of the chest, and particularly for ventilation studies of the lungs, is supported in a flexible vest having arm holes locating the coil elements about the patient.

Abstract: System and method for actively canceling the acoustic noise generated by changes in the electric current within the gradient coils of a magnetic resonance imager based on the finding that the acoustic noise in the magnetic resonance imager is highly periodic but that the period of the magnetic resonance imager noise changes substantially during a scan. The acoustic noise signal is measured at the ears of a patient undergoing a magnetic resonance imaging, delayed by a variable number of samples and the resulting signal is subtracted from the acoustic noise signal. Magnetic resonance imaging noise cancellation occurs at the level of 20 decibels or more.

Abstract: A flexible peripheral coil for magnetic resonance imaging provides a tapered volume conforming to a patient through the use of multiple flexible leaves of decreasing combined length which enclose progressively smaller cylindrical areas while maintaining correct coil orientation. A freestanding foot coil may be placed over the patient's foot with toes passing through an aperture in the coil to complete the scanning coverage area. Straps allow the various coil leaves to accommodate different body sizes effectively varying the taper of the coil.

Abstract: A magnetic resonance imaging (MRI) system is provided with an interventional instrument with an indicator element which influences, for example locally disturbs, the magnetic resonance image. The position of the interventional instrument within the patient to be examined is derived from the local disturbances in the image as caused by the interventional instrument. The degree of influencing of the magnetic resonance image is adjustable notably by rotation of the interventional instrument with the indicator element relative to the direction of the steady magnetic field of the magnetic resonance imaging system. For example, the indicator element is a paramagnetic strip which may include several segments of different magnetic susceptibility.

Abstract: A system for determining displacement of an osseous target underlaying soft tissue assists in the diagnosis of disorders of the musculoskeletal system. The system includes an untrasonic transducer/indenter which is used to compress the target tissue while concurrently obtaining ultrasound data. The displacement of the osseous target is determined by subtracting soft tissue compression from the overall displacement of the transducer/indenter. The transducer/indenter may be mechanically actuated or manually actuated.

Abstract: A method of transesophageal magnetic resonance analysis of a patient, such as an animal or human, includes providing a loopless antenna formed from a flexible coaxial cable having an extended center conductor at the distal end thereof. A distal portion of the loopless antenna is secured within a Levin-type gastric tube. The gastric tube which receives the loopless antenna is inserted in the esophagus of the patient. A tuning, matching and decoupling circuit for the loopless antenna is employed external to the patient. The tuning, matching and decoupling circuit is electrically connected to a magnetic resonance imaging scanner. The magnetic resonance imaging scanner is employed to display an image of the aorta of the patient.

Abstract: A method for creating improved homogeneity in magnetic flux density in a radio frequency resonator for magnetic resonance imaging and spectroscopy of the human head. A tapered birdcage resonator is also provided. The tapered birdcage resonator includes two electrically conductive rings and a plurality of rods or conductor legs. The first electrically conductive ring forms an inferior end of the coil. The plurality of legs extends from the first electrically conductive ring. Each of the plurality of legs has a linear portion and a tapered portion. The second electrically conductive ring forms a superior end of the coil and is connected to the tapered portion of the plurality of legs.

Abstract: A probe 1, for use with magnetic resonance imaging apparatus, which is designed to be inserted into and removed from a patient and which comprises a former 2 upon which an r.f. coil 3 is mounted is characterised in that the former also carries at least one transducer or sensor 6-9 by which the targeting of energy relating to an interventional procedure to an area in the vicinity of the transducer may be controlled both as to position and strength.

Abstract: A transportable magnetic resonance imaging apparatus, said apparatus comprising a transportable platform, provided with a casing made of ferromagnetic metal, and a magnetic resonance imaging system mounted onto said transportable platform, said magnetic resonance imaging system comprising a front end and a back end, the front end comprising a magnetic structure for the provision of a magnetic field, at least two gradient coils, RF transmit coil, and RF receive coil, and the back end comprising a host computer as a central processing unit, at least two gradient amplifiers, RF amplifier, MRI spectrometer, MRI controller and display unit, wherein said apparatus is provided with a positioning assembly for moving and positioning said magnetic structure between a first position and a second position, said first position being such that a patient's body part is positioned between said magnetic field, and said second position being such that said pair of magnets is positioned inside said casing, when not in use,

Abstract: A double-resonance coil for use in MRI having a coil element, a first input/output terminal coupled to the coil element, and a second input/output terminal coupled to the coil element. A first resonance means is coupled between the coil element and the first input/output terminal to cause the MRI coil to resonate at a first MRI frequency, and a second resonance means is coupled between the coil element and the second input/output terminal to cause the MRI coil to resonate at a second MRI frequency substantially different than the first MRI frequency. The double resonance coil includes a first frequency-blocking means coupled to the coil element for substantially preventing the second MRI frequency from being detected at the first input/output terminal and a second frequency-blocking means coupled to the coil element for substantially preventing the first MRI frequency from being detected at the second input/output terminal.

Abstract: An antenna array for magnetic resonance examinations has array elements that are decoupled from each other and that are independent, the array elements being arranged in two adjacent rows. Each array elements is formed by two antenna elements whose respective sensitivity axes reside perpendicular to one another.

Abstract: Sound energy of a proximally arranged sound source 30 and laser radiation of a therapeutic laser 17 are simultaneously transmitted with an endoscopic instrument via flexible waveguides 3 into the body interior. The sound energy is in a power and frequency range adequate for the cutting tissue 16 and the therapeutic laser 7 operates preferably in the near infrared. The waveguides are quartz glass fibers 3 which can transmit sound energy as well as also light energy.

Abstract: The design and construction of a novel phased array echoplanar receiver system for magnetic resonance imaging for use with a standard clinical EPI system is described, and in vivo results showing increased SNR are presented.

Abstract: A family of NMR coils based on Litz foil conductor groups is disclosed. The simplest embodiment is a two-element Litz foil coil. The foils are joined at node (1) and node (2) and are electrically insulated at crossover (3). When the coil is positioned in a plane perpendicular to a uniform magnetic field, the areas (A) defining two flux sub-windows must be equal.

Abstract: A magnetic resonance imaging apparatus includes a main magnet (12) for generating a main magnetic field in an examination region (14) and a radio frequency coil assembly. The radio frequency coil assembly transmits radio frequency pulses into the examination region (14) to induce magnetic resonance in selected dipoles disposed therein. The radio frequency coil assembly also receives signals from selected resonating dipoles. The radio frequency coil assembly includes a birdcage coil (60) having a plurality of conductive elements (64) constructed on a dielectric form positioned about the examination region (14). The birdcage coil (60) includes a plurality of capacitors (C1-C24) and corresponding plurality of series connected diode inductor pairs connected in parallel with each capacitor to form resonant trap circuits.

Abstract: Electromagnetic shielding device for nuclear magnetic resonance apparati, having a cavity (5) with at least one or more openings for introducing the body (K) or the part thereof under examination, which cavity (5) is defined by at least one magnet (1) for generating a static field, one or more coils for generating a magnetic field gradient (2), one or more coils (3) for generating spin-exciting radio-frequency pulses, and one or more coils (4) for receiving echo signals. The transmitting (3) and receiving coils (4) are contained in an electromagnetic shielding structure (7, 7', 7"), at the openings of the detection cavity (5), whereat the shielding structure may be closed by removable shielding elements (9, 10, 18, 20), electrically connectable thereto.

Abstract: A scan using an NMR imaging system is carried out while applying an oscillating stress to the object being imaged. An alternating magnetic field gradient synchronized with the applied stress is employed in the NMR imaging pulse sequence to detect and measure synchronous spin motion throughout the field of view. The direction of the alternating gradient and/or the applied stress may be changed to measure and image the elastic properties of the object.

Abstract: The invention provides a device for correlating the internal location of an anatomical point of a human or animal patient with a location on the external body contours of the patient.

Abstract: Electromagnetic body coil for magnetic resonance tomographic measurements, whereby the body coil has a three-dimensional coil shape and is assembled from at least two partial coils which are capable of being brought into a state of detachable plug-in connection with one another by means of an electrical plug-in connection arrangement and whereby a first partial coil is located inside a cushion, that serves as a patient resting aid, and the second partial coil is located outside this cushion.

Abstract: Annular portions are arranged on mutually confronting surfaces at circumferential edge portions of low-temperature containers, the annular portions forming annular containing portions whose cross section is rectangular. Not only a side coil among a group of coils forming a collective coil body is disposed inside the containing portion, but also a gradient magnetic field unit, a radio-frequency transmission coil, and a reception coil are disposed inside a recessed portion so as to be integrated with one another into a single body, the recessed portion being formed so as to be surrounded by the corresponding annular portion. The side coil supplies more than half a designed magnetomotive force. Since a distance J of the mutually confronting low-temperature containers, i.e.

Abstract: An MRI apparatus for imaging an object includes a base, a pair of magnets, and a transceiver unit. The magnets are mounted on the base with the North pole face of one magnet facing the South pole face of the other magnet. The North pole face and the South pole face are each substantially arcuate, and are positioned on the base to establish a magnetic field in a substantially U-shaped region between the North pole face and the South pole face. Importantly, imaging is performed in a nonhomogeneous portion of this magnetic field. This portion is characterized by substantially parallel surfaces having mutually different constant magnetic field magnitudes. Importantly, the space between the magnets at the top of the U-shaped region creates an access into the U-shaped region. To image an object, the object is placed through the access and into the portion of the magnetic field having surfaces of constant magnetic field magnitude.

Abstract: The invention relates to A method for imaging jointed movable parts of an object by magnetic resonance, where a third part of the object moves along a trajectory near a pivot between a first and a second part of the object, and where the position of the third part is dependent, in conformity with a predetermined relation, on an orientation of the first and the second part relative to the pivot. The method is used, for example for forming a series of images of the patella during the movement of the knee of a human body. According to the method, the measuring zone is adjusted to the instantaneous position of the patella in order to generate imaging pulse sequences. An angle formed by the orientations of the lower leg and the upper leg with respect to one another is measured in order to determine the instantaneous position of the patella. The angle can be determined from the position of RF coils fastened to the lower leg and the upper leg.

Abstract: A magnetic resonance device has a main field magnet system which generates a steady magnetic field in an examination zone. The main field magnet system includes a yoke structure which consists of two yoke plates and a yoke wall interconnecting the two yoke plates, a pole block which is arranged inside the yoke device, and below an examination zone, and a coil which is arranged within the yoke system and above the examination zone. In order to ensure that a patient present in the examination zone can also undergo further treatments and is freely accessible during an MR examination, the inner space of the coil as well as the space between the coil and the examination zone remains free from components of the magnet system, the coil being constructed so as to be ring-shaped and encloses the examination zone essentially in such a manner that the patient is freely accessible from above and from the sides.

Abstract: In a method for determining the time curve of the basic field of a nuclear magnetic resonance tomography apparatus under switched gradients, a phase-encoding gradient Gvx is prefixed to a readout gradient Gox. The time position of the signal maximum of a nuclear magnetic resonance signal S under the readout gradient Gox is determined. This is repeated n times with different gradient time surfaces of the phase-encoding gradient. The curve of the phase position over the temporal position of the signal maxima yields the phase error that occurs due to fluctuations of the basic magnetic field.