CN110558986A - Phase contrast imaging method suitable for magnetic resonance imaging - Google Patents
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Abstract
The invention relates to a phase contrast imaging method suitable for magnetic resonance imaging, which comprises the following steps: step one, applying flow velocity encoding gradient in three directions of a frequency encoding direction, a phase encoding direction and a frequency encoding direction. And step two, reconstructing the obtained phase difference value graphs in the three directions by adopting a subtraction method, and performing SOS processing. And step three, carrying out MIP projection and displaying the blood vessel image. Therefore, the data processing is simpler, and under the condition that the gradient applied in the three directions does not exceed the maximum limit of the system, the sizes of the bipolar coding gradients in the three directions only need to be calculated respectively, so that the display of each blood vessel is clearer, more uniform and more continuous, and meanwhile, the background signal is suppressed more thoroughly.
Description
Technical Field
The present invention relates to an imaging method, and more particularly, to a phase contrast imaging method suitable for magnetic resonance imaging.
Background
Magnetic Resonance Imaging (MRI) typically uses amplitude images, while phase information is discarded. Phase Contrast (PC) imaging does not, it uses the Phase change of the macroscopic transverse magnetization vector caused by the flow to suppress the background, highlight the vessel signal, by adding a flow-encoding gradient. Meanwhile, the defect that TOF imaging is limited by blood flow speed is overcome, slow blood flow is well presented, and the method is suitable for vein examination; the background tissue has good inhibition, and is beneficial to displaying small blood vessels, blood vessel stenosis and aneurysm.
The flow rate encoding gradient, i.e. the bipolar gradient, used, as shown in fig. 1, is two gradient fields of equal size and duration but opposite direction, and the gradient used is usually trapezoidal, and here is shown as a rectangle to simplify the illustration. The horizontal axis is the time axis and the vertical axis is the gradient magnitude, G0-bipolar gradient magnitude,T-gradient application duration, time difference of T-bipolar gradient application, a-single-step gradient area (for rectangular gradients in the figure, a = G0 ×)t）。
As shown in fig. 2, the horizontal axis is a time axis, the vertical axis represents the phase accumulation magnitude of protons under the bipolar gradient of fig. 1, the effect of the bipolar gradient field on the proton group of the stationary tissue can just be completely cancelled, the phase change of the transverse magnetization vector caused by the first gradient field is completely corrected by the second gradient field, so that the transverse magnetization vector phase of the stationary tissue at the time TE is changed to zero, and as shown by the solid line, the phase accumulation of protons at two positions x1 and x2 is zero after the bipolar gradient application is completed; however, the bipolar gradient field causes phase accumulation on the flowing proton groups, since the position of the flowing proton group changes when the gradient field is applied twice, the flowing proton group changes from the position x1 to the position x2, and cannot experience two gradient fields with the same strength and duration but opposite directions, the phase change of the transverse magnetization vector caused by the first gradient field cannot be completely corrected by the second gradient field, so the phase change of the transverse magnetization vector of the flowing proton group at the time TE is preserved, the phase difference existing between the flowing proton group and the stationary tissue forms a phase contrast, the gradient magnitude at the position x1 is smaller than that at the position x2 according to the slope of the proton phase accumulation slope lines at the positions x1 and x2, and the proton at the position x1 moves to the position x2 after the time T due to the motion, so that at this time, under the effect of the second gradient, the phase accumulation line of the proton at the position x2 is shown as a dotted line, after bipolar gradient application is complete, the phase accumulation is not zero.
fig. 3 is a typical PC sequence diagram, in which the RF axis represents the pulse application axis, SS the slice selection direction, PE the phase encoding direction, arrows indicate the direction in which the phase encoding gradient value changes, the former phase encoding gradient value decreases from a positive value, the latter phase encoding gradient value increases from a negative value, FE the frequency encoding direction, signal the signal axis, the solid line the sequence diagram in which no bipolar velocity encoding gradient is applied, and the dotted line represents the application of the bipolar velocity encoding gradient. At the same time, bipolar gradients are integrated with other gradients to reduce time. After rf pulse excitation, the bipolar gradient field is applied between the slice select gradient and the readout gradient, usually in only one direction at a time, and in sequence in three directions if arbitrary directional phase contrast maps are to be obtained.
The phase change of the flowing proton group accumulated in the period of applying the bipolar gradient field is related to the flow velocity, the faster the flow velocity is, the more obvious the phase change is, the relationship of the phase and the velocity of the flowing proton group accumulated in the bipolar gradient field is given by formula (1),For the magnetic rotation ratio, a is the area of the unipolar gradient field, i.e. the integral over time of the gradient G0, as in fig. 1, a = G0 for a simplified rectangular gradientT, T is the time difference of bipolar gradient field application, v is the blood flow velocity, and the phase difference is obtainedTo display the blood vessel image, so as to obtain a PC-MRA image。
The maximum phase change reflected by the PC-MRA is 180 degrees, if the phase exceeds 180 degrees, the phase change is mistaken as the reverse change of the phase, so the false image of reverse blood flow is caused, therefore, a velocity encoding (Venc) needs to be set, under the application of a bipolar gradient, the corresponding accumulated phase change of the velocity is 180 degrees, and the amplitude G0 and the duration of the bipolar gradient needing to be applied are calculated by setting the Venc valueT and the application time difference T value. For blood flow with high flow speed, selecting a large speed coding value, such as Venc of 80-200cm/s, so as to prevent blood vessel signals from generating reverse black low signals after the blood flow speed is larger than the Venc value; venc is 40-80cm/s for medium-speed blood flow; whereas for slow blood flow Venc a smaller value is often chosen, about 10cm/s, if a high Venc value is chosen for slow blood flow, the phase accumulation caused by the blood flow is not large enough to clearly display the vessel signal, making the vessel indistinguishable from the background tissue. Therefore, the proper Venc value is selected for blood flows with different flow rates, so that the blood vessels can be distinguished from background tissues and have contrast on the final display, namely the PC-MRA imaging effect is better.
Disclosure of Invention
the present invention is directed to solving the above problems in the prior art, and provides a phase contrast imaging method suitable for magnetic resonance imaging.
The technical scheme of the invention is as follows: a phase contrast imaging method suitable for magnetic resonance imaging, comprising the steps of: step one, applying flow velocity encoding gradient in three directions of a frequency encoding direction, a phase encoding direction and a frequency encoding direction; reconstructing the obtained phase difference graphs in the three directions by adopting a subtraction method, and performing SOS treatment; and step three, carrying out MIP projection and displaying the blood vessel image.
The phase contrast imaging method suitable for magnetic resonance imaging described above, wherein: the flow rate encoding gradient is that the exact same pair is applied to three directions by defaultAnd polar gradients, namely FE, PE and SS are adopted to respectively represent a frequency encoding direction, a phase encoding direction and a slice selection direction in turn. Setting Venc values in three directions to be a value within an interval of 10-100cm/s manually, and applying bipolar velocity encoding gradients in the three directions respectively in sequence, wherein the same bipolar gradient amplitude G0 is used in the three directions for the durationT and the value of the application time difference T and the echo time TE, saidAnd when T =0, the value range of T is 3-10ms, and the value range of TE is 10-17 ms.
Further, the above phase contrast imaging method suitable for magnetic resonance imaging, wherein: the Venc value is expressed as Venc-FE, Venc-PE and Venc-SS according to the frequency coding direction, the phase coding direction and the layer selection direction, and is set to Venc-SS =75cm/s, Venc-FE =60cm/s and Venc-PE =55 cm/s. With the set Venc-FE, Venc-PE and Venc-SS values and known durationsT and the value of the application time difference T according to the formulaRespectively correspondingly calculating the amplitudes of the bipolar gradients in three directions to obtain G0-FE，G0-PEAnd G0-SS。
Still further, the phase contrast imaging method suitable for magnetic resonance imaging described above, wherein: in the second step, a phase-difference method or a complete-difference method is adopted for subtraction. The phase-difference method comprises the steps of sequentially applying bipolar flow velocity encoding gradients to three directions in an image domain to obtain phases of images, respectively subtracting the phases of reference image images from voxels to obtain a phase difference value map of the three directions, wherein the phase difference value is in direct proportion to flow velocity, and the relation is shown as a formulaAs shown, the SOS mode is that the sum of squares of phase contrast images in three directions is subjected to the root sign, and the displayed image reflects the blood flow velocity in any direction. The Complex-difference method comprises the steps of sequentially applying bipolar flow rate coding gradients in three directions in an image domain, directly carrying out voxel-by-voxel Complex subtraction on an obtained Complex image and a reference image, then taking a module value to obtain phase contrast images in the three directions, and obtaining a phase contrast image reflecting blood flow velocity in any direction in an SOS mode.
The technical scheme of the invention has the advantages that: the data processing is simpler, and under the condition that the gradient applied in three directions does not exceed the maximum limit of the system, the sizes of bipolar coding gradients in the three directions are only required to be calculated respectively, so that the display of each blood vessel is clearer, more uniform and more continuous, and meanwhile, the background signal is suppressed more thoroughly.
Drawings
Fig. 1 is a bipolar gradient field schematic.
Fig. 2 is a schematic diagram of phase accumulation.
Fig. 3 is a typical PC sequence diagram.
FIG. 4 is a graph of Venc value of 75cm/s versus bipolar gradient.
Fig. 5 is a graph of the Venc values Venc-FE =60cm/s, Venc-PE =55cm/s, Venc-SS =75cm/s, respectively, versus bipolar gradient.
fig. 6 is a craniocerebral sagittal blood vessel map of Venc =75 cm/s.
fig. 7 is a cranio-sagittal blood vessel map of Venc-FE =60cm/s, Venc-PE =55cm/s, Venc-SS =75 cm/s.
Fig. 8 is a cranio-sagittal blood vessel map of Venc-FE =50cm/s, Venc-PE =40cm/s, Venc-SS =75 cm/s.
Detailed Description
The phase contrast imaging method suitable for magnetic resonance imaging as shown in fig. 1 to 7 is distinctive in that it comprises the following steps:
Step one, applying flow velocity encoding gradient in three directions of a frequency encoding direction, a phase encoding direction and a frequency encoding direction. Specifically, the flow rate encoding gradient is a bipolar gradient which is applied by default in three directions and is completely the same, namely, FE, PE and SS are adopted to respectively represent the frequency encoding direction, the phase encoding direction and the slice selection direction in turn. During this period, the Venc values in the three directions are manually set to the same value, and the value range is generally 10-100cm/s (since the Venc value =75cm/s is generally selected in the conventional PC artery vessel imaging at present, and the Venc value =10cm/s is generally selected in the PC vein vessel imaging).
In combination with practical implementation, the Venc value needs to be set according to the actual speed of blood flow, and a proper Venc value is selected, so that the PC-MRA imaging effect is better, the contrast between blood vessels and background tissues is more obvious, and the appearance of small blood vessels, vascular stenosis, aneurysms and the like is more facilitated. At the same time, the phase cannot be accumulated due to blood flow perpendicular to the bipolar velocity encoding direction. For this reason, only one Venc value setting is given for each manufacturer's PC sequence interface setting, i.e., by default, exactly the same bipolar gradient is applied to all three directions, as shown in FIG. 4. Then, the bipolar velocity encoding gradient is applied in three directions in sequence, and the same bipolar gradient amplitude G0 is used in all three directions for the same durationT and the value of the application time difference T and the echo time TE.And when T =0, the value range of T is 3-10ms, and the value range of TE is 10-17 ms.
in practice, the main blood flow direction of a human body such as the head is along the head and foot directions, so the Venc value in the direction can be properly large, but the blood flow speed in the left-right direction and the front-back direction is relatively slow, for example, the same Venc value is set: if Venc value is large, the blood accumulation phase in the direction of slow blood flow velocity is not large enough, so that the blood vessel and the background tissue are not obviously contrasted. After the SOS processing, the information of the background tissue of partial degree contained in the left-right direction and the front-back direction phase difference map is also added into the final image, which will certainly affect the display effect of the whole head blood vessel. If Venc is small, the phase of blood accumulation in the direction of fast blood flow rate is far beyond 180 °, which may cause the artifact of reverse blood flow, and the blood flow rate is fast at the turn of the blood vessel, which may also cause the discontinuity of the blood vessel display.
for this reason, as shown in fig. 5, the Venc values used in the present invention can be expressed as Venc-FE, Venc-PE, and Venc-SS according to the frequency encoding direction, the phase encoding direction, and the layer selection direction. For example, the SS direction is the head and foot direction, and the blood flow velocity in the direction can even reach 100 cm/s. Venc-SS =75cm/s may be set, and the blood flow velocities in the other two directions (front-back direction and left-right direction) are small, Venc-FE =60cm/s and Venc-PE =55cm/s may be set. In actual scanning, different Venc values can be set for three directions respectively according to actual conditions, and then different bipolar velocity encoding gradients are applied, so that the blood vessel-background tissue contrast in the three directions is strongest to the greatest extent.
With the set Venc-FE, Venc-PE and Venc-SS values and known durationsT and the value of the application time difference T according to the formulaRespectively correspondingly calculating the amplitudes of the bipolar gradients in three directions to obtain G0-FE，G0-PEAnd G0-SS。
And step two, reconstructing the obtained phase difference value graphs in the three directions by adopting a subtraction method, and performing SOS processing. The subtraction can be performed by using phase-difference or complete-difference method to remove the background tissue signal and highlight the blood vessel signal, so as to present a clear image.
Specifically, the phase-difference method is a method in which bipolar flow rate encoding gradients are sequentially applied to three directions in an image domain to obtain phases of an image, and the phases of a reference image are subtracted voxel by voxel to obtain a phase difference map in the three directions. The phase difference is proportional to the flow rate, as expressed by the equationAs shown. And then, the phase contrast images in the three directions are subjected to an SOS mode of square summation and root opening, so that the displayed image reflects the blood flow velocity in any direction.
The Complex-difference method is that in an image domain, bipolar flow rate coding gradients are sequentially applied to three directions, an obtained Complex image and a reference image are directly subjected to voxel-by-voxel Complex subtraction, and then a modulus value is taken to obtain phase contrast images in the three directions. And finally, obtaining a phase contrast map reflecting the blood flow velocity in any direction by an SOS mode.
And step three, carrying out MIP projection and displaying the blood vessel image.
in view of practical use of the present invention, since a lower Venc value needs to be set in a direction where the blood flow velocity is slow, a larger gradient value needs to be used in a case where the gradient time is not changed, and if Venc =10cm/s and TE is set around 10ms, the amplitude of the bipolar gradient can reach approximately 40mT/m, which is a great test for system hardware.
at the same time, the delay time between bipolar gradients cannot be lengthened too much, nor can the application duration be lengthened too much to relieve the pressure of the system gradients. Only if a shorter TE is guaranteed, can our final image have a higher signal-to-noise ratio.
Therefore, in the case of no compatibility, a trade-off is made between the two, both to shorten TE as much as possible to ensure a higher signal-to-noise ratio, and to use as much as possible a maximum gradient value that is allowed by the gradient amplifier that does not exceed its limit.
In combination with practical implementation, as shown in fig. 6 to 8, three blood vessel images are obtained by acquiring a NEX from a PC2D sequence, and fig. 6 is a craniocerebral sagittal blood vessel image with the same velocity code applied in three directions (Venc =75 cm/s), and it can be seen that the blood vessel with the faster upper and lower blood vessel flow velocity shows more obviously.
Fig. 7 is a diagram of a cranio-sagittal vessel with different velocity codes applied in three directions (Venc-FE =60cm/s, Venc-PE =55cm/s, Venc-SS =75 cm/s), showing that vessels with relatively slow flow velocity before and after and to the left and right appear more than in fig. 6.
Fig. 8 is a cranio-sagittal blood vessel map of three directions with different velocity codes applied (Venc-FE =50cm/s, Venc-PE =40cm/s, Venc-SS =75 cm/s), showing that intracranial blood vessels are more uniformly intense and the blood vessels are more continuous.
It can be seen from the above description that, after the present invention is adopted, data processing is simpler, and under the condition of ensuring that the gradients applied in the three directions do not exceed the maximum limit of the system, the sizes of the bipolar coding gradients in the three directions only need to be calculated respectively, but each blood vessel can be displayed more clearly, uniformly and continuously, and meanwhile, the background signal is suppressed more thoroughly.
Claims (4)
1. A phase contrast imaging method suitable for magnetic resonance imaging, characterized by comprising the steps of:
Step one, applying flow velocity encoding gradient in three directions of a frequency encoding direction, a phase encoding direction and a frequency encoding direction;
Reconstructing the obtained phase difference graphs in the three directions by adopting a subtraction method, and performing SOS treatment;
And step three, carrying out MIP projection and displaying the blood vessel image.
2. A phase contrast imaging method suitable for magnetic resonance imaging according to claim 1, characterized in that: the flow rate encoding gradient is a bipolar gradient which is applied to three directions in a default way and is completely the same, namely FE, PE and SS are adopted to respectively represent a frequency encoding direction, a phase encoding direction and a layer selection direction in turn,
Setting Venc values in three directions to be a value within an interval of 10-100cm/s manually, and applying bipolar velocity encoding gradients in the three directions respectively in sequence, wherein the same bipolar gradient amplitude G0 is used in the three directions for the durationT and the value of the application time difference T and the echo time TE, saidAnd when T =0, the value range of T is 3-10ms, and the value range of TE is 10-17 ms.
3. A phase contrast imaging method suitable for magnetic resonance imaging according to claim 2, characterized in that: the Venc value is expressed as Venc-FE, Venc-PE and Venc-SS according to the frequency coding direction, the phase coding direction and the layer selection direction, and is set as Venc-SS =75cm/s, Venc-FE =60cm/s and Venc-PE =55cm/s,
With the set Venc-FE, Venc-PE and Venc-SS values and known durationst and the value of the application time difference T according to the formulaRespectively correspondingly calculating the amplitudes of the bipolar gradients in three directions to obtain G0-FE，G0-PEAnd G0-SS。
4. A phase contrast imaging method suitable for magnetic resonance imaging according to claim 1, characterized in that: in the second step, the subtraction is performed by using a phase-difference method or a complete-difference method,
The phase-difference method comprises the steps of sequentially applying bipolar flow velocity encoding gradients to three directions in an image domain to obtain phases of images, respectively subtracting the phases of reference image images from voxels to obtain a phase difference value map of the three directions, wherein the phase difference value is in direct proportion to flow velocity, and the relation is shown as a formulaIn the SOS mode, the sum of squares of phase contrast images in three directions is carried out, and the root is opened, so that the displayed image reflects the blood flow velocity in any direction;
The Complex-difference method comprises the steps of sequentially applying bipolar flow rate coding gradients in three directions in an image domain, directly carrying out voxel-by-voxel Complex subtraction on an obtained Complex image and a reference image, then taking a module value to obtain phase contrast images in the three directions, and obtaining a phase contrast image reflecting blood flow velocity in any direction in an SOS mode.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112118392A (en) * | 2020-10-09 | 2020-12-22 | 中山北方晶华精密光学有限公司 | An integrated optical device focusing and zooming control system |
| CN113900056A (en) * | 2021-10-18 | 2022-01-07 | 国家纳米科学中心 | Flow velocity measurement method, device and storage medium |
| CN116369894A (en) * | 2023-04-17 | 2023-07-04 | 复旦大学附属中山医院 | Foot magnetic resonance angiography system based on physical heating |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5897496A (en) * | 1996-09-03 | 1999-04-27 | Hitachi Medical Corporation | Method and apparatus for producing magnetic resonance angiogram |
| JP2001070279A (en) * | 1999-09-06 | 2001-03-21 | Hitachi Medical Corp | Magnetic resonance imaging instrument |
| JP2006130116A (en) * | 2004-11-08 | 2006-05-25 | Hitachi Medical Corp | Magnetic resonance imaging equipment |
| US20110064294A1 (en) * | 2008-05-22 | 2011-03-17 | Takayuki Abe | Magnetic resonance imaging apparatus and blood vessel image acquiring method |
| US20120268125A1 (en) * | 2011-04-21 | 2012-10-25 | Andreas Greiser | Dynamic adaptation of a dephasing gradient pair |
| CN103675739A (en) * | 2012-09-25 | 2014-03-26 | 西门子公司 | Magnetic resonance phase contrast angiography with rotating coding gradients |
-
2019
- 2019-08-27 CN CN201910796541.2A patent/CN110558986A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5897496A (en) * | 1996-09-03 | 1999-04-27 | Hitachi Medical Corporation | Method and apparatus for producing magnetic resonance angiogram |
| JP2001070279A (en) * | 1999-09-06 | 2001-03-21 | Hitachi Medical Corp | Magnetic resonance imaging instrument |
| JP2006130116A (en) * | 2004-11-08 | 2006-05-25 | Hitachi Medical Corp | Magnetic resonance imaging equipment |
| US20110064294A1 (en) * | 2008-05-22 | 2011-03-17 | Takayuki Abe | Magnetic resonance imaging apparatus and blood vessel image acquiring method |
| US20120268125A1 (en) * | 2011-04-21 | 2012-10-25 | Andreas Greiser | Dynamic adaptation of a dephasing gradient pair |
| CN103675739A (en) * | 2012-09-25 | 2014-03-26 | 西门子公司 | Magnetic resonance phase contrast angiography with rotating coding gradients |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112118392A (en) * | 2020-10-09 | 2020-12-22 | 中山北方晶华精密光学有限公司 | An integrated optical device focusing and zooming control system |
| CN113900056A (en) * | 2021-10-18 | 2022-01-07 | 国家纳米科学中心 | Flow velocity measurement method, device and storage medium |
| CN116369894A (en) * | 2023-04-17 | 2023-07-04 | 复旦大学附属中山医院 | Foot magnetic resonance angiography system based on physical heating |
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Application publication date: 20191213 |