JP2002143117A - Method for photographing with contrast medium and mri equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sufficiently obtain the effect of a contrast medium for both of two slabs in the case of photographing a photographic area divided into the two slabs. SOLUTION: An operator makes a patient stop breathing, starts photographing with the contrast medium with MRI equipment and pours the contrast medium a period α later. The MRI equipment 3D-scans the first area with the trajectory of a YZ-K space as a reverse ECVO and is suspended in a period in which the patient can inhale a breath. Then, the equipment 3D-scans the second area with the trajectory of the YZ-K space as an ECVO. Consequently, both of a time difference between the timing when the contrast medium reaches the photographic area and the timing of collecting data near the center of the YZ-K space concerning the first area and a time difference between the timing when the contrast medium reaches the photographic area and the timing of collecting data near the center of the YZ-K space concerning the second area are small. Thus, the effect of the contrast medium can be obtained sufficiently for both of the slabs.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contrast agent imaging method and an MRI (Magnetic Resonance Imaging) apparatus, and more particularly, to a method in which an imaging region is divided into two slabs when imaging is performed. The present invention relates to a contrast agent imaging method and an MRI apparatus capable of sufficiently obtaining an effect.

[0002]

2. Description of the Related Art FIG. 6 shows an example of a pulse sequence of a 3D scan in an MRI apparatus. In this pulse sequence, the RF pulse R and the Z-direction phase axis pulse SL
To excite the imaging region, perform encoding in the YZ space by the Y-direction phase axis pulse PEy and the Z-direction phase axis pulse PEz, and sample the echo echo while performing frequency encoding in the X direction by the read axis pulse RD. Finally, rewinding in the YZ space is performed with the Y-direction phase axis pulse RWy and the Z-direction phase axis pulse RWz. This is Y
The encoding in the YZ space is repeated while being sequentially changed so as to fill the ZK space. Tr is the repetition time.

The trajectory of a data point on the K space in the order of changing the encoding in the YZ space is called a trajectory. 3
The trajectory in the YZ space in the D-scan is used to enhance the contrast effect. EllipticalCentric View Ordering
May be adopted. Hereinafter, “elliptical centric view ordering” is described as “ECVO”. FIG. 7 is a conceptual diagram showing ECVO. In ECVO, data is sequentially collected in a trajectory that spirals from the center of the K space to the outer periphery. For ECVO, refer to “Performance of an Elliptical Centric ViewOrd”.
er for Signal Enhancement and Motion Artifact Supp
ression in Breath-hold Three-Dimensional Gradient
Echo Imaging: Alan H. Wilman, Stephen J. Riederer: M
RM 38: 793-802 (1997) ".

FIG. 8 and FIG. 9 are explanatory views of a conventional one-slab contrast medium imaging method. As shown in FIG. 8, a contrast agent is injected into an injection site v on the upstream side of the blood flow toward the imaging region. Then, as shown in FIG. 9, the subject h is stopped from breathing at the timing when the contrast agent reaches the imaging region, and a 3D scan of the imaging region is performed. YZ- of this 3D scan
The trajectory of the K space is ECVO. The breath-holding time is limited to about 30 seconds.
It is necessary to end the D scan, and the length of the imaging area in the Z direction is limited.

FIGS. 10 and 11 are explanatory views of a conventional two-slab contrast medium imaging method. As shown in FIG.
The imaging region is divided into a first region and a second region, and a contrast agent is injected into an injection place v on the upstream side of the blood flow toward the imaging region. Then, as shown in FIG. 11, at the timing when the contrast agent reaches the imaging region, the subject h is stopped from breathing, and the 3D scan of the first region is performed. 3 of the first area within 30 seconds
After the D scan, the subject h is inhaled again. Then, the subject stops breathing again and performs a 3D scan of the second area. The trajectory of the 3D scan in the YZ-K space is
ECVO. The breath holding time is limited to about 30 seconds, and it is necessary to finish the 3D scanning within 30 seconds. However, since the breathing is performed again and the 3D scanning is repeated twice, the length of the imaging area in the Z direction is increased. I can do it.

[0006]

The contrast of an image is governed by data near the center of the K space. FIG.
In the 3D scan, since the timing at which the contrast agent arrives at the imaging region and the timing at which data near the center of the YZ-K space are collected are close to each other, the contrast agent effect sufficiently contributes to the contrast of the image, and there is no problem. However, the 3D of FIG.
In the scan, there is no problem for the first area, but the second area
For the region, the timing of arrival of the contrast agent and YZ-K
Since the timing of collecting data near the center of the space is far, there is a problem that the contrast agent effect does not sufficiently contribute to image contrast. Therefore, an object of the present invention is to provide a contrast agent imaging method and an MRI apparatus capable of sufficiently obtaining a contrast agent effect in both slabs when an imaging region is divided into two slabs of a first region and a second region. Is to provide.

[0007]

According to a first aspect of the present invention, a contrast medium is injected into a subject, and a Y-axis is used as a lead axis in the X direction.
A contrast agent imaging method in which an imaging area is 3D scanned with the direction and the Z direction as phase axes, the imaging area is divided into a first area and a second area in the Z direction, the first area is imaged, and a pause is inserted. Then, when photographing the second area, the first
The timing of the photographing time and the pause time is determined so that the contrast agent reaches the photographing region during the second half of the photographing time of the region and the photographing time of the second region. In the photographing of the first region, the YZ-K space is used. Data is collected sequentially in a trajectory that spirals from the outer circumference to the center of the YZ-K space, while data is sequentially collected in a trajectory that spirals from the center of the YZ-K space to the outer circumference in imaging of the second region. Provided is a contrast agent imaging method. In the contrast agent imaging method according to the first aspect, a 3D scan is performed on the first area before the timing and a 3D scan is performed on the second area after the timing with the timing when the contrast agent reaches the imaging area. I made it. Furthermore, 3 of the first area
In the D scan, the order of trajectories spirals from the outer periphery of the YZ-K space to the center, and in the 3D scan of the second region, the order of trajectories spirals from the center of the YZ-K space to the outer periphery. As a result, the timing at which the contrast agent arrives at the imaging region and the timing at which data near the center of the YZ-K space are collected are close to both the first region and the second region. A sufficient contrast agent effect can be obtained.

According to a second aspect of the present invention, in the contrast agent imaging method having the above structure, the trajectory at the time of imaging of the first area is in accordance with inverse elliptical centric view ordering, and the trajectory at the time of imaging of the first area is elliptical. A contrast agent imaging method is provided, which obeys optical centric view ordering. In the contrast agent imaging method according to the second aspect, the trajectory of the first area is set to inverse ECVO, and the trajectory of the second area is set to ECVO, so that the contrast agent imaging method according to the first aspect can be suitably performed.

According to a third aspect, the present invention collects data in a trajectory which spirals from the outer periphery of the YZ-K space to the center with the X direction as a lead axis, the Y direction and the Z direction as phase axes, and sequentially collects data. A first region photographing means for photographing one region, and after a pause time, data is sequentially stored in a trajectory spirally extending from the center of the YZ-K space to the outer periphery with the X direction as the lead axis, the Y direction and the Z direction as the phase axes. And a second region photographing means for photographing the second region by collecting the second region. In the MRI apparatus according to the third aspect, the contrast agent imaging method according to the first aspect can be suitably implemented.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to the embodiments shown in the drawings. Note that the present invention is not limited by this.

FIG. 1 shows an MR according to an embodiment of the present invention.
It is a block diagram which shows I apparatus. This MRI apparatus 100
, The magnet assembly 1 has a space portion (bore) for inserting the subject therein, and a static magnetic field coil 1p for applying a constant static magnetic field to the subject so as to surround the space portion; A gradient magnetic field coil 1g for generating a gradient magnetic field of the X, Y, and Z axes (a slice gradient axis, a read gradient axis, and a phase encode gradient axis are formed by a combination of the X, Y, and Z axes); A transmission coil 1t for applying an RF pulse for exciting spins of nuclei in the subject and a receiving coil 1r for detecting an NMR signal from the subject are arranged. The static magnetic field coil 1p, the gradient magnetic field coil 1g, the transmitting coil 1t, and the receiving coil 1r are connected to a static magnetic field power supply 2, a gradient magnetic field driving circuit 3, an RF power amplifier 4, and a preamplifier 5, respectively.

The sequence storage circuit 6 responds to a command from the computer 7 and, based on the stored pulse sequence (for example, the pulse sequence in FIG. 6), drives the gradient magnetic field drive circuit 3
To generate a gradient magnetic field from the gradient magnetic field coil 1g of the magnet assembly 1 and operate the gate modulation circuit 8 to convert the carrier output signal of the RF oscillation circuit 9 into a pulse signal having a predetermined timing and a predetermined envelope shape. Modulate,
It is applied to the RF power amplifier 4 as an RF pulse,
After the power is amplified by the power amplifier 4, the power is applied to the transmission coil 1t of the magnet assembly 1 to selectively excite a desired imaging region.

The preamplifier 5 includes a magnet assembly 1
, And amplifies the NMR signal from the subject detected by the receiving coil 1 r and inputs the amplified signal to the phase detector 10. Phase detector 10
Uses the carrier output signal of the RF oscillation circuit 9 as a reference signal,
Phase detection of the NMR signal from the preamplifier 5 and A / D
It is given to the converter 11. The A / D converter 11 converts the analog signal after phase detection into digital data,
To enter.

The computer 7 reads digital data from the A / D converter 11 and performs an image reconstruction operation to generate an MR image. Further, the computer 7 is responsible for overall control such as receiving information input from the operation console 12. The display device 13 displays an MR image and the like.

FIG. 2 shows the above M when the contrast region is photographed by dividing the photographing region into two slabs of a first region and a second region.
6 is a flowchart of a contrast agent imaging process by the RI device 100. In Step P1, the first area is 3D scanned. The trajectory in the YZ-K space is an inverse ECVO. FIG. 4 shows the trajectory of the inverse ECVO. In Step P2, the subject h is paused for a time period during which the subject h can breathe again. In Step P3, the second area is scanned in 3D. The trajectory in the YZ-K space is ECVO.
FIG. 5 shows a trajectory of ECVO.

FIG. 3 is a timing chart in a case where the imaging region is divided into two slabs of a first region and a second region and a contrast agent is photographed. Injection location v of subject h shown in FIG.
The time from the injection of the contrast agent into the imaging region until the contrast agent reaches the imaging region is T, the pause time is τr, the time of one 3D scan is τ, and the contrast agent extends from the start of the pause time to the imaging region. Is the time it takes for the first slab to reach 3
When the time from the start of the D scan to the injection of the contrast agent into the injection location v of the subject h is α, there is a relationship α = τ + β−T. Therefore, the operator may cause the subject h to hold his / her breath, start the contrast agent imaging process of FIG. 2, and inject the contrast agent α hours later.

According to the above-described MRI apparatus 100, the timing at which the contrast agent arrives at the imaging region and the first region
The time difference between the timing at which data near the center of the ZK space is collected is about β, and the timing at which the contrast agent arrives at the imaging region and the timing at which data around the center of the YZ-K space are collected for the second region. Is about (τr-
β), and for both the first region and the second region,
It will be a short time. Therefore, a sufficient contrast agent effect can be obtained with both slabs.

[0018]

According to the contrast agent imaging method and the MRI apparatus of the present invention, the timing at which the contrast agent arrives at the imaging region and the timing at which data near the center of the YZ-K space are collected are also determined for the first region. , And also for the second area,
Since the distances are close to each other, a sufficient contrast agent effect can be obtained with both slabs.

[Brief description of the drawings]

FIG. 1 is a block diagram of an MRI apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart of a contrast agent imaging process according to an embodiment of the present invention in a case where an imaging region is divided into two slabs of a first region and a second region and imaging is performed.

FIG. 3 is a timing chart of a contrast agent photographing process according to an embodiment of the present invention in a case where a contrast region is photographed while dividing a photographing region into two slabs of a first region and a second region.

FIG. 4 is a conceptual diagram showing a trajectory of inverse ECVO.

FIG. 5 is a conceptual diagram showing a trajectory of ECVO.

FIG. 6 is an exemplary diagram of a pulse sequence of a 3D scan.

FIG. 7 is a conceptual diagram showing a trajectory of ECVO.

FIG. 8 is an explanatory diagram in a case where a contrast agent is photographed in a photographing region of one slab.

FIG. 9 is a timing chart in a case where a contrast agent is photographed in a photographing region of one slab.

FIG. 10 is an explanatory diagram in a case where a contrast agent is photographed while dividing a photographing region into two slabs of a first region and a second region.

FIG. 11 is a timing chart in a case where a contrast agent is photographed while dividing the photographing region into two slabs of a first region and a second region.

[Explanation of symbols]

 6 Sequence storage circuit 7 Computer 100 MRI apparatus

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hiroshi Sato 127 Gee Yokogawa Medical System Co., Ltd., 4-7, Asahigaoka, Hino City, Tokyo (72) Inventor Koichi Kato 4-7 Asahigaoka, Hino City, Tokyo No.127 GE Yokogawa Medical System Co., Ltd. (72) Inventor Akihisa Yamazaki 1-36F, Amanuma 3-chome, Suginami-ku, Tokyo 4C096 AA11 AB04 AD06 AD07 AD27 BA13 BA18 BB05 BB18 BB28 DA01 DA19

Claims (3)

[Claims] 1. A contrast agent imaging method for injecting a contrast agent into a subject and performing 3D scanning of an imaging region with the X direction as a lead axis and the Y and Z directions as phase axes, wherein the imaging region is positioned in the Z direction. When the first area is photographed, a pause is inserted, and then the second area is photographed, the second area is photographed from the latter half of the photographing time of the first area to the photographing time of the second area. The timing of the imaging time and the pause time is determined so that the contrast agent reaches the imaging area during the imaging, and data is sequentially collected in the trajectory that spirals from the outer periphery of the YZ-K space to the center in the imaging of the first area. And
On the other hand, in the imaging of the second area, a contrast agent imaging method characterized in that data is sequentially collected in a trajectory spiraling from the center to the outer periphery of the YZ-K space. 2. The contrast agent imaging method according to claim 1, wherein the trajectory at the time of imaging of the first area is in accordance with inverse elliptical centric view ordering, and the trajectory at the time of imaging of the first area is elliptical centric view ordering. A contrast agent imaging method characterized by following. 3. A first area for photographing a first area by sequentially collecting data in a trajectory spiraling from the outer periphery of the YZ-K space to the center with the X direction as a lead axis and the Y and Z directions as phase axes. X after shooting means and pause
Direction as a lead axis, Y direction and Z direction as phase axes, and Y
An MRI apparatus comprising: a second region photographing means for sequentially acquiring data in a trajectory spiraling from the center of the ZK space to the outer periphery to photograph a second region.