WO2010057564A1 - Ensemble de réception multicanaux pour irm - Google Patents

Ensemble de réception multicanaux pour irm Download PDF

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Publication number
WO2010057564A1
WO2010057564A1 PCT/EP2009/007718 EP2009007718W WO2010057564A1 WO 2010057564 A1 WO2010057564 A1 WO 2010057564A1 EP 2009007718 W EP2009007718 W EP 2009007718W WO 2010057564 A1 WO2010057564 A1 WO 2010057564A1
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WO
WIPO (PCT)
Prior art keywords
coils
coil
recording device
circuit
aufnahmeeinrichtung
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/EP2009/007718
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German (de)
English (en)
Inventor
Jörn EWALD
Florian Meise
Torsten Hertz
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LMT MEDICAL SYSTEMS GmbH
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LMT MEDICAL SYSTEMS GmbH
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Filing date
Publication date
Application filed by LMT MEDICAL SYSTEMS GmbH filed Critical LMT MEDICAL SYSTEMS GmbH
Publication of WO2010057564A1 publication Critical patent/WO2010057564A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
    • G01R33/32—Excitation or detection systems, e.g. using radio frequency signals
    • G01R33/34—Constructional details, e.g. resonators, specially adapted to MR
    • G01R33/341—Constructional details, e.g. resonators, specially adapted to MR comprising surface coils
    • G01R33/3415—Constructional details, e.g. resonators, specially adapted to MR comprising surface coils comprising arrays of sub-coils, i.e. phased-array coils with flexible receiver channels
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
    • G01R33/32—Excitation or detection systems, e.g. using radio frequency signals
    • G01R33/34—Constructional details, e.g. resonators, specially adapted to MR
    • G01R33/34084—Constructional details, e.g. resonators, specially adapted to MR implantable coils or coils being geometrically adaptable to the sample, e.g. flexible coils or coils comprising mutually movable parts

Definitions

  • the invention relates to a multi-channel recording device for magnetic resonance tomography (MRT) with a plurality of arrangements of partially overlapping rectangular coils, which are arranged on one or more coil carriers.
  • MRT magnetic resonance tomography
  • MR coils such recording devices are referred to as MR coils. If one brings such a coil arrangement in the vicinity of the patient to be examined - e.g. through surface contact - this is also known as local coils.
  • the nuclear magnetic resonance signals are picked up by nuclear magnetic cores (primarily protons, i.e., nuclei of hydrogen) upon excitation thereof by radio frequency. The frequency of these signals depends on the magnetic field strength.
  • a strong magnetic field typically 1.5 Tesla through one or more magnetic fields with gradients, the nuclear magnetic resonance signals can be measured at various points of the body and mosaically combined to form an overall image.
  • a local coil as a multiple coil (array antenna, US Pat. No. 4,825,162) is known. This consists of an arrangement of juxtaposed partially overlapping individual coils. By means of the individual coils, the nuclear magnetic resonance signals of different body regions can be recorded substantially separated from one another, which optionally results in an improved overall image or a shortened examination time (parallel imaging). By combining a plurality of relatively small area MR coils into an array, the benefits of a large field of view and a high signal-to-noise ratio are brought into coincidence.
  • the individual coils have a simple geometric and planar structure, for example as a loop or toroidal coil. The mutual influence of adjacent coils is greatly reduced, inter alia, by the partial overlap of adjacent coils.
  • the object of the invention is to provide a receiving device of the type mentioned, which is particularly suitable for infants and neonates (newborns).
  • the solution according to the invention is that it has at least two arrangements of partially overlapping rectangular coils which are curved.
  • At least one of the rectangular coils is flexible.
  • one of the arrangements of rectangular coils is attached to a coil support, which is designed as a slightly curved patient bed, while the other arrangement of rectangular coils is attached to a coil carrier, which can be adapted as a particular padded element to the body of the patient.
  • the trained as a patient bed base takes into account the desired imaging of the spine from the neck area to at least down to the rump.
  • the longitudinal axis of the patient couch corresponds to the z-axis and the orientation of the main magnetic field B 0 in the MRI.
  • the flexible other coil carrier the upper part, can be placed on the regions to be examined - the thorax or abdomen / pelvis of the patient. Due to the flexible structure which is flexible in the xy plane and padded as a cushion, the contour can be adapted to the patient in an advantageous manner and, if appropriate, be displaced in the z-direction into the desired field of vision.
  • Another advantageous embodiment is characterized in that the rectangular coils are arranged on a cylindrical coil carrier. Also in this case The rectangular coils enclose the child's body at a small distance.
  • this embodiment is particularly suitable for examining the child's head.
  • the compact design of the coil carriers and the coils creates the possibility of using the arrangement in an MR-compatible incubator.
  • more than one arrangement of rectangular coils are provided on at least one coil carrier, in particular on the couch formed.
  • adjacent coils are alternately provided on the front and the back of a printed circuit.
  • preamplifiers for the coils are each provided in the interior of the coils.
  • the space-saving positioning of the preamplifier on the inner surface of the coil, in addition to a compact design of the coil has the advantage of a very short lead for the signal to be amplified per channel.
  • preamplifiers of two adjacent coils are provided in pairs in the interior of each second coil, wherein the interior of each other second coil is transparent or air-permeable due to a corresponding recess of the coil carrier, for example, to facilitate breathing.
  • means are provided for detuning the resonant frequency of individual coils. It can thereby be achieved that the coil is not excited to resonance during the transmission phase of the MRI.
  • the coils have an overcurrent fuse, in particular a fuse.
  • This fuse protects in case of error - e.g. at very high current increase in the conductor of the coils, caused by an (unintentionally) uncoordinated coil during the transmission phase of the MRI - the patient from burns.
  • Sheath wave barriers are advantageously provided by which signals are suppressed which are generated by eddy currents generated in the transmission phase in lead shields.
  • FIG. 1a shows an arrangement according to the invention in the open position
  • FIG. 1b shows the arrangement of FIG. 1b in the operating position
  • FIG. Fig. 2a shows the topology of a configured as a shell
  • FIG. 5 shows an exemplary ring antenna with a downstream amplifier circuit
  • 6a is an illustration of a standing wave barrier
  • FIG. 6b a representation of a standing wave barrier according to an alternative concept to FIG. 6a;
  • FIG. 7 shows a circuit implementation of the block diagram from FIG. 5;
  • FIG. 8 shows the frequency response of the RF blocking filter (7.1) from FIG. 7;
  • Fig. Ia and Ib show the basic concept of the invention.
  • the multichannel body coil or its coil carrier is subdivided into an upper part (Ia.1) which is placed on the regions to be examined - the thorax or abdomen / pelvis of the patient (Ib.1). Due to the flexible construction, which is flexible in the xy plane and padded as a cushion, the contour can be adapted to the patient in an advantageous manner and optionally displaced in the z-direction into the desired field of vision.
  • the lower part (Ia.2) is shaped as a patient couch surface slightly curved in the xy plane, which favors use in the MR incubator.
  • the geometry of the base takes into account the desired imaging of the spine from the neck area down to at least the rump. It should be noted that the z-axis also represents the orientation of the main magnetic field B 0 in the MRI.
  • FIGS. 1a and 1b show the array geometries of the coils from which the two coil arrangements are constructed.
  • the brightly drawn coils are printed on the upper side of the board, corresponding to the dark drawn on the lower side of the board on which they are arranged. It is characteristic that the same geometry is used for all coil arrangements.
  • the coil arrangement consists of four coils 1 to 4 overlapping in the x-direction.
  • Each coil constitutes a conductor loop with a self-inductance L A predetermined by its geometry.
  • Fig. 3 illustrates these relationships in detail, namely the details in the areas of the overlap ⁇ and overlap area A of two adjacent coils.
  • the light-colored conductor segments are printed on the upper side of the circuit board, corresponding to the shaded areas on the lower side of the circuit board.
  • FIG. 2b shows the structure of the lower, rigid arrangement of coils 5 to 12.
  • the sub-array of Fig. 2a is used twice - each offset in the z-direction. Also in this direction, the decoupling of pairs opposite coils is achieved by the overlap ⁇ .
  • FIG. 4 shows how the signal respectively received by the coils (4.1) and (4.2) via the symmetrical connection (4.4) resp. (4.5) is fed into the common double preamplifier board (4.3).
  • This board has a point-symmetrical structure with regard to the components as the preamplifier (4.6) resp. (4.7) and standing wave barriers (4.8) resp. (4.9).
  • the supply lines (DC and RX from FIG. 5) are connected to the two short sides of the board (4.3).
  • the pairwise combination of the preamplifier boards is advantageous because the now free inner surface of the loop antenna (4.2) can be cut out and thus a light and air-permeable window to the patient is created.
  • Fig. 5 the structure of a channel of the preamplifier board is shown on the level of function blocks.
  • the final received signal to the MRI is RX; With the control signal DC coming from the MRT, the coil can be deliberately detuned and thus switched off.
  • the coil (5.1) is supplemented by a tuning circuit (5.2), which is realized in the simplest case with a capacitor C A. This forms in series with the two series-connected capacitors in the balancing circuit (5.3) C s, the capacitive component to the inductively embossed part L A of the conductor loop of the coil.
  • the resonance frequency can thus be represented as follows:
  • the C s are fixed and set the entire coil by means of C A by adjustment or targeted value selection to the resonant frequency.
  • the fuse (5.8) protects the patient from burns, for example when there is a very strong current increase in the conductor of the coil caused by an (unintentionally) unsanctioned antenna during the transmission phase of the MRI.
  • the balanced signal applied to the coil is asymmetrically decoupled by means of the balancing circuit (5.3), ie related to ground.
  • This signal is fed into the preamplifier (5.6), but via a decoupling circuit (5.5) located in its input path.
  • this is a capacitive component -j / ⁇ C with which the coupling-active component + jc ⁇ M ( (caused by the remaining interaction M 'between adjacent ring antennas) is completely compensated.
  • the preamplifier itself is a modular component with a fixed voltage gain v. This is dimensioned so that the signal received by the antenna on the from the
  • the structure of the standing wave barrier (5.7) is shown in Fig. 6a.
  • the signal coming from the preamp output is shielded signal cable (6a.1) is wound on a toroidal winding body (6a.2) made of Teflon (in real about 18 turns).
  • the shielding is effective as inductance L MWS .
  • the screen is bridged by a tunable capacitor C MWS (6a.4) and hereby a blocking filter for f 0 is realized via this parallel resonant circuit.
  • the signal is thus conducted via the inner conductor (6a.4) of the coaxial cable (6a.1) wound on the toroidal body (6a.2).
  • the braided screen is bridged with an adjustable capacitor (6a.3).
  • the blocking frequency is adjusted to f o and thus the sheath current is effectively suppressed, which is caused by eddy currents generated in the shield during the transmission phase by the radiated high frequency.
  • FIG. 6b An alternative construction of the standing wave barrier is shown in FIG. 6b.
  • the coaxial cable (6b.1) is wound on a cylindrical winding body (6b.2) instead of a toroidal body.
  • the winding body is hollow on the inside and takes up a copper core (6b.5) whose immersion depth is e.g. is adjustable via a thread.
  • the capacitor (6b.3) can therefore be provided as a fixed value CMWS; the resulting resonance frequency f 0 is again calculated according to the above formula.
  • the detuning circuit (5.4) is explained in more detail by circuit diagram Fig. 7.
  • a DC control current coming from the MRT (approx. 100mA) is conducted via an HF cut-off filter (7.1) via the current path formed by the PIN diode (7.2) and the detuning inductance (7.3) to ground.
  • the PIN diode In the forward direction, the PIN diode is virtually a closed switch due to its very low differential internal resistance, which makes the detuning inductance (7.3) act in the resonant circuit of the coil.
  • the resonance frequency is shifted from f 0 to £ ⁇ . Since the MRI system registers only resonances and signals near f 0 , the respective tuned channel is invisible to MRT.
  • the Verstimminduktivitat (7.3) can for example be designed so that it corresponds to the inductance L A of the coil. In the case of detuning, the total inductance is thus 2L A , which implies:
  • the detuning frequency fi is thus far enough away from the actual MRT resonance frequency f 0 .
  • the RF rejection filter (7.1) prevents short circuiting of the high frequency signals from the coil's point of view through the DC source of the MRI; From the point of view of the MRI, (7.1) prevents the coupling of high-frequency signals; its frequency response is shown in Fig. 8.
  • the lower tap thus represents the now asymmetric (ground related) output of the otherwise symmetric coil.
  • FIG. 9 shows a coil configuration which is based on the arrangement of FIG. 2a.
  • the arrangement extended in the x-direction to 8 individual coils is rolled up to form a cylindrical outer surface, so that the first and last individual coil again overlap with ⁇ , thus resulting in a rotationally symmetrical structure.
  • Such a hollow cylinder can be advantageously, e.g. placing the head of a newborn, which combines the benefits of high image resolution, high signal-to-noise ratio, and the potential for parallel imaging.
  • 10 shows the advantageous arrangement a) of the amplifier boards (10.1, four boards according to FIG. 4) in the region of the individual coils 2, 3, 6 and 7 and b) of the viewing windows (10.2) in the region of the individual coils 1, 4, 5 and 8th.
  • the proximity of the amplifier boards to the individual coils has an advantageous effect on the signal quality.

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  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Magnetic Resonance Imaging Apparatus (AREA)

Abstract

L'invention concerne un ensemble de réception utilisé pour l'imagerie par résonance magnétique (IRM) et comprenant plusieurs ensembles de bobines rectangulaires (1-8) qui se chevauchent partiellement, qui sont disposées sur au moins un support de bobine. L'invention est caractérisée en ce que l'ensemble comporte au moins deux ensembles convexes de bobines rectangulaires (1-8) qui se chevauchent au moins partiellement.
PCT/EP2009/007718 2008-11-18 2009-10-28 Ensemble de réception multicanaux pour irm Ceased WO2010057564A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE200820015239 DE202008015239U1 (de) 2008-11-18 2008-11-18 Mehrkanalige Aufnahmeeinrichtung zur MR-Bildgebung
DE202008015239.9 2008-11-18

Publications (1)

Publication Number Publication Date
WO2010057564A1 true WO2010057564A1 (fr) 2010-05-27

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PCT/EP2009/007718 Ceased WO2010057564A1 (fr) 2008-11-18 2009-10-28 Ensemble de réception multicanaux pour irm

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9461350B2 (en) 2013-02-01 2016-10-04 Siemens Aktiengesellschaft Coaxial cable arrangement with a standing wave trap comprised of an adjustable dielectric resonator device
US10613164B2 (en) 2016-11-17 2020-04-07 Siemens Healthcare Gmbh Magnetic resonance coil arrangement having a flexible local coil and a rigid local coil

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997026548A1 (fr) * 1996-01-19 1997-07-24 Philips Electronics N.V. Circuit de combinaison pour systeme de bobines de mesure rf permettant de detecter des signaux de resonnance magnetique
DE102004052943A1 (de) * 2003-11-04 2005-06-23 General Electric Co. Integrierte Zervikal-Thorakal-Lumbar-Wirbelsäulen-MRI-Array-Spule
DE102005020025A1 (de) * 2004-05-14 2005-12-01 General Electric Co. HF-Spulenarray für Mehrkanal MRI
US20060267586A1 (en) * 2004-11-16 2006-11-30 Kabushiki Kaisha Toshiba Radio frequency coil assembly and magnetic resonance imaging apparatus
EP1875862A1 (fr) * 2005-04-25 2008-01-09 Hitachi, Ltd. Équipement d'inspection employant la résonance magnétique

Family Cites Families (1)

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US4825162A (en) 1987-12-07 1989-04-25 General Electric Company Nuclear magnetic resonance (NMR) imaging with multiple surface coils

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997026548A1 (fr) * 1996-01-19 1997-07-24 Philips Electronics N.V. Circuit de combinaison pour systeme de bobines de mesure rf permettant de detecter des signaux de resonnance magnetique
DE102004052943A1 (de) * 2003-11-04 2005-06-23 General Electric Co. Integrierte Zervikal-Thorakal-Lumbar-Wirbelsäulen-MRI-Array-Spule
DE102005020025A1 (de) * 2004-05-14 2005-12-01 General Electric Co. HF-Spulenarray für Mehrkanal MRI
US20060267586A1 (en) * 2004-11-16 2006-11-30 Kabushiki Kaisha Toshiba Radio frequency coil assembly and magnetic resonance imaging apparatus
EP1875862A1 (fr) * 2005-04-25 2008-01-09 Hitachi, Ltd. Équipement d'inspection employant la résonance magnétique

Non-Patent Citations (6)

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Title
D.HERLIHY ET AL.: "A clover leaf coil array for neonatal cardiac imaging at 3T", PROC.INTL.SOC.MAG.RESON.MED. 14, 2006, pages 2586, XP002561029 *
HAYES C E ET AL: "VOLUME IMAGING WITH MR PHASED ARRAYS", MAGNETIC RESONANCE IN MEDICINE, ACADEMIC PRESS, DULUTH, MN, US, vol. 18, no. 2, 1 April 1991 (1991-04-01), pages 309 - 319, XP000209845, ISSN: 0740-3194 *
K.NAEL ET AL.: "Multistation Whole-Body High-Spatial-Resolution MR Angiography Using a 32-Channel MR System", AJR, vol. 188, 2007, pages 529 - 539, XP002561028 *
RADIOLOGY ONESOURCE: "Pediatric Array", 2007, XP002561032, Retrieved from the Internet <URL:http://www.scanmed.com/content/pds_pediatric.pdf> [retrieved on 20091217] *
SIEMENS MEDICAL SOLUTIONS: "Small Pediatric Coil - Avanto 1.5T", 2005, XP002561031, Retrieved from the Internet <URL:http://www.saegeling-mt.de/radiologie/produkte/spulen_pdfs/datenblatt/800211_PED_Avanto.pdf> [retrieved on 20091217] *
T.GRAFENDORFER ET AL.: "An 8-Channel Array Adapted for Pediatric Cardiac Imaging", PROC.INTL.SOC.MAG.RESON.MED. 16, May 2008 (2008-05-01), pages 439, XP002561030 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9461350B2 (en) 2013-02-01 2016-10-04 Siemens Aktiengesellschaft Coaxial cable arrangement with a standing wave trap comprised of an adjustable dielectric resonator device
US10613164B2 (en) 2016-11-17 2020-04-07 Siemens Healthcare Gmbh Magnetic resonance coil arrangement having a flexible local coil and a rigid local coil

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