JP3209819B2 - MRI equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an MRI apparatus,
More specifically, the present invention relates to an MRI apparatus capable of efficiently performing another process performed before image reconstruction.

[0002]

2. Description of the Related Art FIG. 5 is a block diagram of a main part of a conventional MRI apparatus. In the MRI apparatus 51, the scanning processor 2 generates a gradient magnetic field with the gradient magnetic field coil 3 based on the stored sequence. Further, the RF signal is applied to the RF coil 5 via the amplifier 4. Further, information such as scan parameters is transmitted to each unit.
The NMR signal obtained by the RF coil 5 is amplified by an amplifier 6 and then converted into a digital value NM by an A / D converter 7.
The data is converted to R data and input to the data collection processor 58. The data collection processor 58 collects NMR data. Further, another processing before image reconstruction is performed. The image reconstruction processor 9 performs image reconstruction based on the NMR data stored in the data storage memory 10,
Generate image data.

[0005] Next, referring to a flow chart shown in FIG.
The operation of the I device 51 will be described. First, in step S1, the user sets scan parameters in the scan processor 2. In step S2, the scanning processor 2 starts scanning. In step S3,
As shown in the time chart of FIG. 7, the data collection processor 58 outputs the idle time T1 (data collection time Tacq
(From the shaded area to the next data collection time Tacq), another processing A1 in the processing time unit T2 is performed. However,
The last separate processing A2 is executed after the scan end P1. By performing the separate process T2 during the idle time T1, the time from the start of scanning P0 to the end of the image reconstruction RC is reduced. In step S4, the image reconstruction processor 9 performs image reconstruction to generate image data.

[0004]

In the above-described conventional MRI apparatus 51, the repetition time TR is sufficiently large.
Another process before image reconstruction is performed in the idle time T1 during which the data acquisition processor 58 acquires NMR data,
The whole process could be made more efficient. However, in recent years, when a high-speed pulse sequence has been developed and the repetition time TR has become shorter, there is no room for performing another process in the idle time T1, and as shown in FIG. A1 must be performed. But,
In this case, when a pulse sequence having a long repetition time TR is used, there is a problem that the idle time T1 is wasted. SUMMARY OF THE INVENTION It is an object of the present invention to provide an MRI apparatus capable of performing another process before image reconstruction most efficiently according to a pulse sequence used for scanning.

[0005]

According to the MRI apparatus of the present invention, the vacant time during which the data acquisition processor does not collect NMR data is T1, and the processing time unit of another process performed before image reconstruction is T2 or T3. M where (T2> T3)
In the RI device, the data collection processor performs another processing of the processing time unit T2 in the free time T1 if the free time T1 ≧ the processing time unit T2, and performs the processing time in the free time T1 if the free time T1 ≧ the processing time unit T3. If the free time T1 <the processing time unit T3, the separate process of the unit T3 is performed, and all the separate processes are performed after the scan in the order of priority described above.

[0006]

According to the MRI apparatus of the present invention, the vacant time T1 during which the data acquisition processor acquires NMR data is T1.
Is compared with a processing time unit T2 or T3 (T2> T3) of another processing performed before image reconstruction, and it is determined whether another processing can be performed in the idle time T1, and a priority is assigned to another processing. Execute For this reason, another process can be performed in the most efficient manner according to the pulse sequence, and the overall processing time can be reduced.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. It should be noted that the present invention is not limited by this.

FIG. 1 is a block diagram of a main part of an MRI apparatus according to the present invention. In the MRI apparatus 1, the scanning processor 2 performs, based on the stored sequence,
A gradient magnetic field is generated by the gradient magnetic field coil 3. Also, RF
The signal is applied to the RF coil 5 via the amplifier 4. Further, information such as scan parameters is transmitted to each unit. The NMR signal obtained by the RF coil 5 is amplified by an amplifier 6, converted into digital NMR data by an A / D converter 7, and input to a data collection processor 8. The data collection processor 8 collects NMR data. Further, another processing before image reconstruction is performed according to the determined processing method. The image reconstruction processor 9 includes:
Image reconstruction is performed based on the NMR data stored in the data storage memory 10 to generate image data.

Next, referring to the flow chart shown in FIG.
The operation of the RI device 1 will be described. First, in step ST1, the user sets scan parameters in the scan processor 2. If a numerical example of a scan parameter is given, a repetition time TR = 30 [ms] and the number of slices N
slc = 1, number of echoes Nch = 1, number of data in the depth direction during 3D scanning Ndpt = 64, number of samples Nsm
p = 512.

In step ST2, the data collection processor 8 determines another processing method according to the set scan parameters. The processing procedure will be described with reference to the flowchart of FIG. In step SU1, a scan parameter set by the user is received from the scan processor 2.

In step SU2, a free time T1 during which NMR data is collected is calculated. For this purpose, the following operation, Tscn = TR / (Nslc * Nech), is performed to calculate the scan time Tscn per frame, and data collection per frame is performed using a predetermined function, Tacq = f (Nsmp). The time Tacq may be calculated, and the following calculation, T1 = Tscn−Tacq, may be performed to calculate the idle time T1. Specifically, using the above numerical example, the scan time Tscn = 30 / (1 * 1) = 30 [m
s] Data collection time Tacq = f (512) = 5 [ms] Free time T1 = 30−5 = 25 [ms].

In step SU3, a processing time unit T2 of another processing is calculated. For example, assuming that the processing time unit T2 is the time required for the DFT in the depth direction between frames, the processing time unit T2 is calculated by a predetermined function: T2 = g (Ndpt, Nsmp). T2 = g (64,512) = 20 [ms] if specifically shown using the above numerical example.

In step SU4, if free time T1 ≧ processing time unit T2, the process proceeds to step SU5, where free time T
If 1 <processing time unit T2, the process proceeds to step SU6. For example, according to the above numerical example, the idle time T1 = 25 [m
s] ≧ processing time unit T2 = 20 [ms], so the process proceeds to step SU5.

In step SU5, the processing method of another processing is determined as the processing method. As shown in the time chart of FIG. 4A, the processing method is based on the idle time T1 (data collection time Tacq (shaded area) to the next data collection time Tacq).
During the period up to acq), another processing A1 of the processing time unit T2 is performed. However, the last separate processing A2 is executed after the scan end P1. In this processing method, the time from the start of scanning P0 to the end of the image reconstruction RC can be reduced.

In step SU6, another process in the processing time unit T2 is divided into another process in the processing time unit T3 (<T2). For example, the processing time unit T3 is calculated by the following operation: T3 = T2 / N (N: number of divisions). The number of divisions N
Is preferably determined in consideration of the processing speed of another process after division. For example, using the above numerical example with the number of divisions N = 8, T3 = 20/8 = 2.5 [ms].

In step SU7, if idle time T1 ≧ processing time unit T3, the process proceeds to step SU8, where idle time T
If 1 <processing time unit T3, the process proceeds to step SU9.

In step SU8, a processing method of another processing is determined as a processing method. As shown in the time chart of FIG. 4B, the processing method performs another processing A2 in the processing time unit T3 during the idle time T1. Then, after the scan end P1, the remaining separate processing A2 is performed. In this processing method, the time from the scan start P0 to the end of the image reconstruction RC is slightly longer than the processing method.

At step SU9, the processing method of another processing is determined as the processing method. In the processing method, as shown in the time chart of FIG. 4C, no separate processing is performed during the idle time T1, and all the separate processing A1 is performed after the scan end P1. In this processing method, the scan start P
The time from 0 to the end of the image reconstruction RC is longer than the processing method.

That is, comparing the efficiencies of the above processing methods, the processing method is the highest, the processing method is the next highest, and the processing method is the lowest.

Returning to FIG. 2, in step ST3, the scanning processor 2 starts scanning. Step S
In T4, the data collection processor 8 performs another process according to the processing method determined in step ST2. In step ST5, the image reconstruction processor 9 performs image reconstruction to generate image data.

[0021]

According to the MRI apparatus of the present invention, the idle time during which the data collection processor collects NMR data is effectively used as another processing time, and the image reconstruction is completed from the start of scanning. Processing time up to

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a main part of an MRI apparatus according to the present invention.

FIG. 2 is a flowchart showing an operation of the MRI apparatus of FIG. 1;

FIG. 3 is a flowchart showing a processing procedure of a data collection processor.

FIG. 4 is a time chart showing the operation of the data collection processor.

FIG. 5 is a configuration diagram of a main part of a conventional MRI apparatus.

6 is a flowchart showing the operation of the MRI apparatus of FIG.

FIG. 7 is another time chart showing the operation of the data collection processor.

FIG. 8 is still another time chart showing the operation of the data collection processor.

[Explanation of symbols]

 1,51 MRI apparatus 2 Scanning processor 3 Gradient magnetic field coil 4 Amplifier 5 RF coil 6 Amplifier 7 A / D converter 8,58 Data collection processor 9 Image reconstruction processor 10 Data storage memory

──────────────────────────────────────────────────続 き Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) A61B 5/055 JICST file (JOIS)

Claims (1)

(57) [Claims] An empty time during which the data acquisition processor does not collect NMR data is T1, and the processing time unit of another processing performed before image reconstruction is T2 or T3 (T2> T2).
3) In the MRI apparatus, the data collection processor performs another processing of the processing time unit T2 in the free time T1 if the free time T1 ≧ the processing time unit T2, and the free time if the free time T1 ≧ the processing time unit T3. An MRI apparatus, wherein another processing of the processing time unit T3 is performed at T1, and if the free time T1 <the processing time unit T3, all the different processing is performed after the scanning in the above-mentioned priority order.