CN103185877A - Double-layer radio frequency receiving coil for magnetic resonance imaging system - Google Patents
Double-layer radio frequency receiving coil for magnetic resonance imaging system Download PDFInfo
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- CN103185877A CN103185877A CN2011104553289A CN201110455328A CN103185877A CN 103185877 A CN103185877 A CN 103185877A CN 2011104553289 A CN2011104553289 A CN 2011104553289A CN 201110455328 A CN201110455328 A CN 201110455328A CN 103185877 A CN103185877 A CN 103185877A
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Abstract
The invention discloses a double-layer radio frequency receiving coil for a magnetic resonance imaging system. The double-layer radio frequency receiving coil for the magnetic resonance imaging system comprises a cylindrical birdcage coil. A cylindrical multichannel phased-array coil or a surface coil array which is combined into a cylindrical shape is sleeved in the birdcage coil in a wrapped mode. The double-layer radio frequency receiving coil for the magnetic resonance imaging system has the advantages of being high in signal to noise ratio of received signals, small in noise relevance of the received signals, and good in receptivity of resonance radio frequency signals.
Description
Technical field
The present invention relates to magnetic resonance imaging system, be specifically related to a kind of RF receiving coil for magnetic resonance imaging system.
Background technology
In magnetic resonance imaging system, RF receiving coil is the detector that receives the hydrogen atom resonance radiofrequency signal of tested tissue.But because received signal is very weak, be subjected to the influence of noise (coming self-checking body and coil itself) bigger, (Signal-to-Noise Ratio, SNR) (the most important index of decision systems image quality) is very restricted to make its signal to noise ratio (S/N ratio).Design by coil and improve that to improve signal to noise ratio (S/N ratio) be one of important research and development field, magnetic resonance imaging field.From the surface coils of monocycle, to the quadrature volume coil, to phased-array coil, MRI receiving coil is over 30 years, and along with the mr imaging technique development, its diversity and technical advance also obtain significant progress.
The RF receiving coil classification is more, can classify by modes such as the scope of application, function and polarity.If by scope of application classification, coil can roughly be divided into three major types such as surface coils, volume coil and phased-array coil.
Surface coils is the single receiving coil of being close to the imaging position, and its structure is flat or slightly crooked single annular (loop).The received field of this coil is extremely inhomogeneous, shows as the closer to the coil radio-frequency field more by force, can sharply descend apart from increasing radio-frequency field with coil surface.Because this receives the shallow deficiency in the visual field, so only be applicable to shallow regional imaging among a small circle.Its imaging region scope and the degree of depth can increase and increase along with coil dimension, but simultaneously owing to the noise of the more multizone that is arrived, its signal to noise ratio (S/N ratio) also can reduce.
Volume coil refers to entirely to contain or to wrap up the cylindrical coil at certain imaging position.This coil has reception and launching site comparatively uniformly in a constant volume, be mainly used in large volume and get imaging on a large scale.But because its size is bigger, its signal to noise ratio (S/N ratio) can be very not high yet.It is most typical to be birdcage coil, is present in its volume at the both direction of xsect quadrature Circular Polarisation radio-frequency field of the same size.
Phased-array coil is the coil array that has two or more unit (as single surface coils) to form.These coils are adjacent one another are, form between a big imaging area.Along with the development of nearly ten years parallel acquisition techniques, and in the clinical practice to the demand day by day of specific region high s/n ratio imaging, this kind coil has become the most popular and state-of-the-art Coil technique.Its maximum characteristics are that the hyperchannel unit carries out synchronous signal acquisition, and magnetic resonance receiving system makes the coil signal to noise ratio (S/N ratio) for individual unit or volume coil significant raising be arranged by these signals being rebuild and being synthesized.Signal to noise ratio (S/N ratio) is more high, just the image taking speed of the resolution of more favourable increase image or raising system.
From the principle, phased-array coil is based on the surface coils composition.But because distinctive signal and the noise synthesis mechanism of magnetic resonance parallel acquisition technique make it have the characteristics that are better than surface coils.This machine-processed simple principle is: when two or more unit of phased-array coil carry out signal when synthetic, signal can addition.For example, tissue regions pair is consistent with it at a distance of the signal that two unit that equate send, and composite signal is exactly 2 times.Simultaneously also can addition (this can cause synthetic back signal to noise ratio (S/N ratio) to reduce) from the noise of these two unit.And the synthetic degree of noise is determined by the distance between these two unit and the noise source and relative direction, generally all less than two direct additive values of noise.When for example the mutually orthogonal one-tenth 90 of noise signal that detects of these two unit is spent, can think when their noise is uncorrelated that synthetic noise just only is original individual unit
Doubly; This is that synthetic signal to noise ratio (S/N ratio) is just brought up to individual unit so
Doubly.And another kind of limiting case, noise is correlated with fully, and so at this moment He Cheng noise also only is original 2 times.Signal to noise ratio (S/N ratio) just with synthetic preceding the same, does not improve.The condition that satisfies this situation is the noise signal that two unit receive suitable same-phase and amplitude, and is overlapping fully as two coils.
In actual applications, in order to utilize the signal plus of signal surface coil, and avoid noise relevant, the phased array sufacing, use general surface coils (circular or square) not have overlapping or the similar grid cell form of definite part area overlapping (as eighth area) is only arranged, the probe field direction of avoiding them and zone have too much consistent, organize shape and zone to put according to required detection again.Allow same interested search coverage, by a plurality of passages of less single surface coils (the more little signal to noise ratio (S/N ratio) of coil is just high), carry out parallel acquisition.So to the imaging region of same size, if the port number of parcel is more many, sum signal is just many so, adds that Noise Correlation is again little, and its overall signal to noise ratio (S/N ratio) also can be along with increase.
But the how single channel size in passage limit diminishes and can bring another negative effect, and the size decreases of individual unit can allow its imaging visual field become littler, and the penetration length of received field shortens.The signal to noise ratio (S/N ratio) of subregion far away of adjusting the distance can not be improved.Most typical problem is exactly the comparison of many people having a common goal phased array head coil and birdcage head coil.General phased array head coil is designed to a plurality of passages (if any 8,16,32,96 passages etc.) and is wrapped on the cylindrical wall equably.Much studies show that, (length is 25 centimetres to the head coil of a typical sizes, diameter is 25 centimetres cylindrical), though add along with port number is whole, the signal to noise ratio (S/N ratio) of overall transversal section can increase, but zone (be 5 cm section as middle radius) SNR increases with port number hardly any change takes place therebetween.But port number is whole doubling whenever, its realization its hardware design and technology are realized difficulty whole adding greatly just.Significantly improve and the benefit that it brings only is the nearer regional SNR in each unit of coil, to the signal to noise ratio (S/N ratio) of head zone line without any raising.Like this, just the homogeneity of these coils is counted increase and is become poorer on the contrary along with coil channel.Therefore, how making the signal to noise ratio (S/N ratio) of coil zone line also along with the unit number of phased-array coil increases and improves, thereby improve its homogeneity simultaneously in the overall signal to noise ratio (S/N ratio) of raising, is the insurmountable technical matters of prior art.
Summary of the invention
The technical problem to be solved in the present invention provides a kind of snr of received signal height, receive the signal noise good double-deck RF receiving coil that is used for magnetic resonance imaging system of radiofrequency signal receptivity that turns down mutually, resonates.
For solving the problems of the technologies described above, the technical solution used in the present invention is:
A kind of double-deck RF receiving coil for magnetic resonance imaging system comprises being birdcage coil cylindraceous, wraps up in the described birdcage coil to be with to be hyperchannel phased-array coil cylindraceous or to be combined into surface coils matrix cylindraceous.
As further improvement in the technical proposal of the present invention:
Described surface coils matrix is made up of a plurality of body coils, and described a plurality of body coils adopt sphere of movements for the elephants shape, " mouth " font or " zero " glyph group synthetic cylindric.Perhaps, described surface coils matrix is made up of a plurality of heart coils, and described a plurality of heart coils adopt sphere of movements for the elephants shape, " mouth " font or " zero " glyph group synthetic cylindric.
The present invention has following advantage:
Double-deck RF receiving coil of the present invention comprises and is birdcage coil cylindraceous, employing is by wrapping up in the mode that is hyperchannel phased-array coil cylindraceous or is combined into surface coils matrix cylindraceous that is with in the birdcage coil that belongs to volume coil, utilize the superior homogeneity of birdcage coil and the optimizable Noise Correlation between birdcage coil and the phased-array coil, make the signal to noise ratio (S/N ratio) in the synthetic whole zone of coil and homogeneity obtain simultaneously increasing and being improved along with port number, have the snr of received signal height, receiving signal noise turns down mutually, the good advantage of resonance radiofrequency signal receptivity.
Description of drawings
Fig. 1 is the structural representation of the embodiment of the invention.
Fig. 2 is the signal to noise ratio (S/N ratio) contrast synoptic diagram of the embodiment of the invention.
Embodiment
As shown in Figure 1, the double-deck RF receiving coil that the embodiment of the invention is used for magnetic resonance imaging system comprises and is birdcage coil 1 cylindraceous, wraps up in the birdcage coil 1 to be with to be hyperchannel phased-array coil 2 cylindraceous.Hyperchannel phased-array coil 2 is 8 passage phased-array coils in the present embodiment, and birdcage coil has a pair of orthogonal modes that can export separately, therefore can regard the coil of 2 passages as.Therefore this combination just has 10 passages, forms the RF receiving coil of 10 passages.
Adopt the equivalent noise resistance matrix method to calculate each interchannel Noise Correlation in the present embodiment.We have supposed that mutual inductance obtains good restraining by the mode that certain regulates isolation between birdcage coil 1 and the hyperchannel phased-array coil 2 in the calculating, and are negligible by the noise that the coil coupling brings.Also hyperchannel phased-array coil 2 and birdcage coil 1 mode of operation are optimized in calculating in addition.General each passage can be found out pattern that a forward current flow is arranged and the pattern of a reverse current flows, and the direction of the electromagnetic field that these two patterns produce is opposite, and the Noise Correlation of they and other passages is also just different so.A plurality of passages just have a plurality of various combinations that form by the different electric current relative directions of each interchannel together the time.Therefore each combination is exactly a kind of mode of operation.The effect noise resistance matrix difference of every kind of pattern, therefore the received field that calculates distributes also just different with signal to noise ratio (S/N ratio).The result has adopted the synthetic pattern to the influence on signal-to-noise ratio (SNR) minimum of noise among the figure.
As shown in Figure 2, under the identical situation of other conditions, the whole signal to noise ratio (S/N ratio) ratio of birdcage coil (birdcage), 8 passage phased-array coils (8 passage phased array), 10 passage phased-array coils (10 passage phased array) and present embodiment (birdcage+8 passage phased arrays) is: 1.0: 2.0: 2.2: 3.0.And uniformity coefficient is (1-(signal to noise ratio (S/N ratio) maximal value-signal to noise ratio (S/N ratio) minimum value)/(signal to noise ratio (S/N ratio) maximal value+signal to noise ratio (S/N ratio) minimum value)), is respectively 1,59%, 39% and 75%.This shows that present embodiment is compared with the traditional phased-array coil that is 10 passages equally with synthetic 8 preceding passage phased-array coils, signal to noise ratio (S/N ratio) and uniformity coefficient all improve a lot.
In addition, hyperchannel phased-array coil 2 also can adopt and be combined into surface coils matrix cylindraceous and substitute.The surface coils matrix then can adopt a plurality of body coils or a plurality of heart coil, and is synthetic cylindric by adopting sphere of movements for the elephants shape, " mouth " font or " zero " glyph group.The signal that even signal by birdcage coil 1 whole imaging region and the decay of phased-array coil unit are fast is synthetic, make originally from the regional signal to noise ratio (S/N ratio) of each cell distance of phased array away from and be improved significantly, simultaneously by selecting the relevant minimum mode of operation of noise, equally also can make whole signal to noise ratio (S/N ratio) also can obtain to a certain degree raising, thereby improve the performance of phased-array coil comprehensively.
The above only is preferred implementation of the present invention, and protection scope of the present invention is not limited in above-mentioned embodiment, and every technical scheme that belongs to the principle of the invention all belongs to protection scope of the present invention.For a person skilled in the art, some improvements and modifications of under the prerequisite that does not break away from principle of the present invention, carrying out, these improvements and modifications also should be considered as protection scope of the present invention.
Claims (3)
1. a double-deck RF receiving coil that is used for magnetic resonance imaging system comprises being birdcage coil cylindraceous, it is characterized in that: wrap up in the described birdcage coil to be with and be hyperchannel phased-array coil cylindraceous or be combined into surface coils matrix cylindraceous.
2. the double-deck RF receiving coil for magnetic resonance imaging system according to claim 1, it is characterized in that: described surface coils matrix is made up of a plurality of body coils, and described a plurality of body coils adopt sphere of movements for the elephants shape, " mouth " font or " zero " glyph group synthetic cylindric.
3. the double-deck RF receiving coil for magnetic resonance imaging system according to claim 1, it is characterized in that: described surface coils matrix is made up of a plurality of heart coils, and described a plurality of heart coils adopt sphere of movements for the elephants shape, " mouth " font or " zero " glyph group synthetic cylindric.
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103645452A (en) * | 2013-12-09 | 2014-03-19 | 深圳市特深电气有限公司 | Multi-channel radio frequency coil device and magnetic resonance imaging system using the device |
| CN105223525A (en) * | 2015-10-23 | 2016-01-06 | 广东电网有限责任公司东莞供电局 | A kind of double-deck circulating type radio-frequency coil measured for composite insulator umbrella skirt aging |
| CN105242224A (en) * | 2015-10-23 | 2016-01-13 | 广东电网有限责任公司东莞供电局 | Close-contact type double layer plane radio frequency coil used for composite insulator detection |
| CN110301916A (en) * | 2019-07-10 | 2019-10-08 | 中国科学院武汉物理与数学研究所 | A kind of MRI coil device for guided focused ultrasonic diagnosis and treatment encephalopathy |
| CN113552515A (en) * | 2021-06-29 | 2021-10-26 | 上海辰光医疗科技股份有限公司 | Dual-core imaging method for animal magnetic resonance imaging |
| CN117054940A (en) * | 2023-08-15 | 2023-11-14 | 浙江大学 | Multi-core detection coil assembly for magnetic resonance imaging |
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| US20060033497A1 (en) * | 2002-11-27 | 2006-02-16 | Thomas Chmielewski | Degenerate birdcage coil and transmit/receive apparatus and method for same |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103645452A (en) * | 2013-12-09 | 2014-03-19 | 深圳市特深电气有限公司 | Multi-channel radio frequency coil device and magnetic resonance imaging system using the device |
| CN105223525A (en) * | 2015-10-23 | 2016-01-06 | 广东电网有限责任公司东莞供电局 | A kind of double-deck circulating type radio-frequency coil measured for composite insulator umbrella skirt aging |
| CN105242224A (en) * | 2015-10-23 | 2016-01-13 | 广东电网有限责任公司东莞供电局 | Close-contact type double layer plane radio frequency coil used for composite insulator detection |
| CN105223525B (en) * | 2015-10-23 | 2017-03-22 | 广东电网有限责任公司东莞供电局 | Double-layer surrounding type radio frequency coil for aging measurement of composite insulator umbrella skirt |
| CN110301916A (en) * | 2019-07-10 | 2019-10-08 | 中国科学院武汉物理与数学研究所 | A kind of MRI coil device for guided focused ultrasonic diagnosis and treatment encephalopathy |
| CN110301916B (en) * | 2019-07-10 | 2020-09-18 | 中国科学院武汉物理与数学研究所 | Magnetic resonance imaging coil device for guiding focused ultrasound to diagnose and treat encephalopathy |
| CN113552515A (en) * | 2021-06-29 | 2021-10-26 | 上海辰光医疗科技股份有限公司 | Dual-core imaging method for animal magnetic resonance imaging |
| CN117054940A (en) * | 2023-08-15 | 2023-11-14 | 浙江大学 | Multi-core detection coil assembly for magnetic resonance imaging |
| CN117054940B (en) * | 2023-08-15 | 2024-03-26 | 浙江大学 | Multi-core detection coil assembly for magnetic resonance imaging |
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| CN103185877B (en) | 2016-05-11 |
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