MRI method and apparatus with synchronized clock timing from the imaging pulse sequence

An imaging unit producing images, and a control unit controlling the imaging unit. The imaging device further comprises: a reference clock unit generating a reference clock; and a signal input/output unit provided between the imaging unit and the control unit and inputting and outputting signals in synchronization with the reference clock generated by the reference clock unit. The control unit comprises: generating unit generating a plurality of control signals; transmitting unit transmitting the plural control signals; receiving unit receiving measurement signals; and extraction unit extracting the measurement signal when the reception times of the measurement signals received by the receiving unit agrees with the extraction timing generated by the generating unit.

Not Applicable.

THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT

Not Applicable.

Not Applicable.

Not Applicable.

BACKGROUND OF THE INVENTION

Technical Field

The present invention relates to an imaging device and an imaging method, more specifically, an imaging device and an imaging method using the nuclear magnetic resonance imaging, which images in vivo information by using the nuclear magnetic resonance phenomenon.

Background Art

Recently, the MRI (Magnetic Resonance Imaging) device using the MRI, which images in vivo information by using the NMR (Nuclear Magnetic Resonance) phenomenon, is noted.

In the conventional MRI device, the pulse generator corresponding to a clock of the MRI measurement must generate stable and accurate pulses at high speed and, for this, special-purpose hardware such as a DSP (Digital Signal Processor), an FPGA (Field-Programmable Gate Array) or others, has been used (refer to Patent Reference 1 and 2).

PATENT REFERENCES

Patent Reference 1: Japanese Patent Application Unexamined Publication No. 09-173316

Patent Reference 2: Japanese Patent Application Unexamined Publication No. 10-213557

BRIEF SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

Such conventional MRI device has a problem that the pulse generator, which is special hardware, is not readily replaceable, and the capacity of the MRI device cannot meet requirements of the pulse sequences which advance day by day.

It has been tried to provide the pulse generator by a general-purpose personal computer, but the OS mounted on the general-purpose personal computer, specifically, the multi-task OS such as Windows (registered trademark) by Microsoft Corporation irregularly executes interruptions, which has made it difficult for the MRI device to generate stable and accurate RF pulses and gradient magnetic field pulses.

An object of the present invention is to provide an imaging device and an imaging method which can produce images by generating pulses of stable and accurate time resolution without using special-purpose hardware.

Means for Solving the Problem

The imaging device according to one aspect of the present invention is the imaging device including an imaging unit producing images, and a control unit controlling the imaging unit, further comprising: a reference clock unit generating a reference clock; and a signal input/output unit provided between the imaging unit and the control unit and inputting and outputting signals in synchronization with the reference clock generated by the reference clock unit, the control unit comprising: generating means generating a plurality of control signals for controlling the imaging unit and generating an extraction timing of extracting measurement signals from the imaging unit; transmitting means transmitting the plural control signals generated by the generating means to the imaging unit via the signal input/output unit in synchronization with the reference clock; receiving means receiving measurement signals from the imaging unit via the signal input/output unit in synchronization with the reference clock and counting reception times of the measurement signals; and extraction means extracting the measurement signal when the reception times of the measurement signals received by the receiving means agrees with the extraction timing generated by the generating means.

In the imaging device described above, it is possible that the generating means generates the plural control signals for controlling the imaging unit, based on a 1st pulse sequence for controlling the imaging unit, and extracts the measurement signal from the imaging unit, based on a 2nd pulse sequence for extracting the measurement signals from the imaging unit.

In the imaging device described above, it is possible that the reference clock includes a first reference clock, and a second reference clock which is different from the first reference clock in the frequency, the transmitting means transmits the plural control means to the imaging unit in synchronization with the first reference clock, and the receiving means receives the measurement signals in synchronization with the second reference clock.

In the imaging device described above, it is possible that the imaging unit is an MRI unit producing images by the nuclear magnetic resonance imaging, and the frequency of the reference clock is in the range of 0.1-2.0 MHz.

In the imaging device described above, it is possible that the imaging device further comprises an external synchronization clock unit generating an external synchronization clock, the control unit further comprising an external synchronization means controlling signal input/output by the signal input/output unit in synchronization with the external synchronization clock generated by the external synchronization clock unit.

The measuring device described according to one aspect of the present invention is the measuring device including a measuring unit for measurement, and a control unit controlling the measuring unit, further comprising: a reference clock unit generating a reference clock; and a signal input/output unit provided between the measuring unit and the control unit and inputting and outputting signals in synchronization with the reference clock generated by the reference clock unit, the control unit comprising: generating means generating a plurality of control signals for controlling the measuring unit and generating an extraction timing of extracting measurement signals from the measuring unit; transmitting means transmitting the plural control signals generated by the generating means via the signal input/output unit in synchronization with the reference clock; receiving means measurement signals from the measuring unit via the signal input/output unit in synchronization with the reference clock and counting a reception numbers of the measurement signals; and extraction means extracting the measurement signal when the reception number of the measurement signals received by the receiving means agrees with the extraction timing generated by the generating means.

The imaging method according to one aspect to the present invention is the imaging method of producing images by an imaging unit comprising: generating a plurality of control signals for controlling the imaging unit; generating an extraction timing of extracting measurement signals from the imaging unit; transmitting the plural control signals to the imaging unit via a signal input/output unit in synchronization with a reference clock; receiving the measurement signals from the imaging unit via the signal input/output unit in synchronization with the reference clock; counting a reception number of the measurement signals from the start of the measurement; and extracting the measurement signal when the reception number of the measurement signals agrees with the extracting timing.

In the imaging device described above, it is possible that the reference clock includes a first reference clock, and a second reference clock which is different form the first reference clock in the frequency, the plural control signals are transmitted to the imaging unit in synchronization with the first reference clock, and the measurement signals are received in synchronization with the second reference clock.

In the imaging device described above, it is possible that the imaging unit is an MRI unit which produces images by nuclear magnetic resonance imaging, and the frequency of the reference clock is in the range of 0.1-2.0 MHz.

The measuring method according to one aspect of the present invention is the measuring method of measuring by a measuring unit comprising: generating a plurality of control signals for controlling the measuring unit; generating an extraction timing of extracting measurement signals from the measuring unit; transmitting the plural control signals to the measuring unit via a signal input/output unit in synchronization with a reference clock; receiving the measurement signals form the measuring unit via the signal input/output unit in synchronization with the reference clock; counting a reception number of the measurement signals from the start of the measurement; and extracting the measurement signal when the reception number of the measurement signals agrees with the extracting timing.

Effects of the Invention

As described above, according to the present invention, the imaging device includes an imaging unit producing images, and a control unit controlling the imaging unit, further comprises: a reference clock unit generating a reference clock; and a signal input/output unit provided between the imaging unit and the control unit and inputting and outputting signals in synchronization with the reference clock generated by the reference clock unit, the control unit comprising: generating means generating a plurality of control signals for controlling the imaging unit and generating an extraction timing of extracting measurement signals from the imaging unit; transmitting means transmitting the plural control signals generated by the generating means to the imaging unit via the signal input/output unit in synchronization with the reference clock; receiving means receiving measurement signals from the imaging unit via the signal input/output unit in synchronization with the reference clock and counting reception times of the measurement signals; and extraction means extracting the measurement signal when the reception times of the measurement signals received by the receiving means agrees with the extraction timing generated by the generating means, whereby images can be produced by generating pulses of stable and accurate time resolution without using special-purpose hardware.

DETAILED DESCRIPTION OF THE INVENTION

Mode for Carrying Out the Invention

One Embodiment

The imaging system according to one embodiment of the present invention will be described with reference to the drawings.FIG. 1is a block diagram of the physical connections of the imaging system according to the present embodiment, which shows the constitution of the imaging system.FIG. 2is a functional block diagram of the functional operation of the imaging system according to the present embodiment, which shows the operation of the imaging system. According to the principles of the imaging system according to one embodiment of the present invention,FIG. 1shows the physical connections andFIG. 2shows functional connections.

As shown inFIG. 1, the imaging system according to the present embodiment comprises an MRI (Magnetic Resonance Imaging) device100using the nuclear magnetic resonance (NMR) imaging (MRI) as a device to be controlled, and a general-purpose personal computer200as a control device for controlling the device to be controlled.

The MRI device100comprises: a digital receiver/transmitter102which transmits and receives digital signals, analog transmitted RF pulses and analog received signals; an XYZ gradient magnetic field power source and a gradient coil104which includes a power source and a coil for applying XYZ gradient magnetic field; a static magnetic field magnet106which applies a static magnetic field; a magnet temperature stabilizer108which stabilizes the magnet temperature; an Low noise RF signal amplifier110which amplifies RF micro signals; an RF power amplifier112which amplifies RF power; an RF coil114which receives and transmits RF signals; a bed for measurement object116which carries an object-to-be-imaged to a prescribed position; an electric injector118which injects a contrast medium in synchronization with pulse sequences; and other devices120such as other imaging modalities, devices which operate in the magnetic resonance imaging, etc.

The digital receiver/transmitter102has the function of A/D converting MRI signals inputted via the Low noise RF signal amplifier110, and the A/D converted signals are sequentially transmitted to a second communication buffer236in synchronization with a reference clock of 0.1-2.0 MHz from a reference clock circuit230.

The MRI device100further comprises a communication interface122for the connection to other devices via USE, LAN, etc.

The general-purpose personal computer200comprises an MPU (Micro Processing Unit)202which is the main CPU; a memory204which is a buffer memory for temporarily storing programs and data necessary for the MPU202to make processing; a GPU (Graphic Processing Unit)206which makes graphic processing and an HDD (Hard Disk Drive)/SSD (Solid State Drive) memory208which stores programs and data. The MPU202, the memory204, the GPU206and the HDD/SSD memory208are mutually connected by a signal bus line210.

The CPU206comprises a computation core specialized for scientific computation to assist the computation processing of the MPU202and make computation processing of a measurement soft module having the priority of using the GPU206to thereby improve the operational stability of the general-purpose personal computer200as a whole.

In the general-purpose personal computer200, Windows (registered trademark) by Microsoft Corporation, for example, is mounted. The multi-task OS, such as Windows (registered trademark), irregularly executes interruption processing.

In the general-purpose personal computer200, an input/output interface212for connecting input and output devices, and a communication interface214for the connection with other devices by USB, LAN, etc. are further mounted. The input/output interface212and the communication interface214are connected to the signal bus line210.

To the input/output interface210, a monitor216, a key board218and a mouse220are connected. An operator operates the general-purpose personal computer200with the monitor216, the key board218and the mouse220.

The reference clock circuit230generates four (seeFIG. 1) reference clocks, at least one of which contains a reference for the synchronous control of the MRI device100. The reference clock circuit230generates a reference clock of a constant period with TCXO (Temperature Compensated Crystal Oscillator) or others. A reference clock of 0.01-100 MHz is generated.

The reference clock may not take the NMR (Nuclear Magnetic Resonance) frequency into consideration. The NMR center frequency is generated and oscillated with the same TCXO that generates the reference clock. The NMR center frequency is used in the digital receiver/transmitter102. In a case, however, that NMR center frequency is lower than 2 MHz, the reference clock and the NMR frequency are sometimes the same.

A first reference clock signal is preferably 1-100 MHz for the excitation RF pulse and 0.01-1 MHz for the gradient magnetic field pulse, and differs for the respective purposes.

The frequency of a second reference clock signal of the present embodiment is preferably above 0.01 MHz including 0.01 MHz, more preferably, in the range of 0.1-2.0 MHz, and further more preferably, 1.0 MHz.

From the view point of generating an idealistic pulse, it is preferable to increase the time-resolution ability, i.e., to realize 100 MHz which is the maximum frequency. However, when the frequency of the reference clock is higher, the processing quantity of the received/transmitted data is enormous. In a case that the pulse generation is simplified to the max, the MRI will be possible even with the reference clock of 0.01 MHz, but the pulse resolution ability becomes too low.

Then, the reference clock of 1 MHz which satisfies the requirement as the excitation RF pulse and the requirement as the gradient magnetic field pulse is preferable.

From the view point of the data processing quantity and the processing quality of the measurement signals, the reference clock is preferable in the range from 0.1 to 2.0 MHz. In this viewpoint as well, the reference clock of 1 MHz described above is in this range and preferable.

There is a possibility that owing to the development of the computer technology, the desirable reference clock will be raised to about 10 MHz in the near future.

In the general-purpose personal computer200, separate from the usual input/output interface212, a general-purpose digital I/O board232is provided. The general-purpose digital I/O board232is connected to the signal bus line210.

Into and from the general-purpose digital I/O board232, control signals for controlling the MRI device100are inputted and outputted in synchronization with the first reference clock signal. Into and from the general-purpose digital i/O board232, measurement signals from the MRI device100, etc. are inputted and outputted in synchronization with the second reference clock signal.

The digital I/O board232operates in synchronization with the reference clock signals as described herein and, when interruption processing takes place in Windows (registered trademark) mounted in the general-purpose personal computer200, is always stably operative without generating time delays and jitters in the inputted/outputted signals.

A first communication buffer234temporarily stores the transmitted data of the control signals transmitted from the digital I/O board232and received data of the measurement signals received by the digital I/O board232.

A second communication buffer236temporarily stores the transmitted data of the control signals transmitted from the first communication buffer234and the received data of the measurement signals received by the first communication buffer234.

The second communication buffer236is connected to the digital receiver/transmitter102, the XYZ gradient magnetic field power source and the gradient coil104, and receives and transmits signals from and to the digital receiver/transmitter102, and transmits control signals to the XYZ gradient magnetic power source and the gradient coil104.

The reference clock from the reference clock circuit230is supplied to the digital I/O board232, the first communication buffer234, the second communication buffer236and the digital receiver/transmitter102to operate them in synchronization with the reference clock.

An external synchronization clock circuit240receives analog inputs, as of heart rates, respirations, the power source clock, etc., and digitally generates a relatively low external synchronization clock, for example, the external synchronization clock of 0.1-60 Hz.

For the heart rates of often a mouse or a man, an external synchronization clock of 0.5-10 Hz is generated, based on inputs from an electrocardiographic monitor, a heart rate meter using infrared radiation.

For the respiration of often a mouse or a man, an external synchronization clock of 0.1-5 Hz is generated, based on the inputs from a pressure sensor using a balloon or others.

For the power source clock, an external synchronization clock of 50 Hz or 60 Hz is generated, based on the inputs from a circuit which digitizes a source AC frequency.

Such interruption processing has the priority over the repetition time TR of the pulse sequence shown in the 11-th row inFIG. 3. By using this function, the repetition time TR can be renewed without changing the pulse sequence file300. Simply, the same clock as the repetition time TR designated by the pulse sequence in the 11-th row inFIG. 3may be inputted.

However, it is also possible that said external synchronization clock240is judged in real time, and an irregular external synchronization may be generated as when the external synchronization clock240is generated for 8 heart rate signals inputted after a one-second blank from the start of a subject patient's respiration.

In the general-purpose personal computer200, separate from the usual input/output interface212, a general-purpose digital I/O board242is further provided. The general-purpose digital i/O board242is connected to the signal bus line210.

The general-purpose digital I/O board242controls the input/output of the signals by the digital I/O board232in synchronization with the external synchronization clock240. This synchronization with the external synchronization clock corresponding to heart rate signal of a man-to-be-detected, measurement signals from the MRI device100are inputted and outputted into and from the general-purpose digital I/O board242.

In the imaging system according to the present embodiment, another general-purpose personal computer250is further provided. The general-purpose personal computer250is connected to the MRI device100and the general-purpose personal computer200via a communication interface252by USB, LAN, etc.

The general-purpose personal computer250reconstructs an image, based on measurement data.

In the present embodiment described above, the reference clock circuit230generates one reference clock, and, in synchronization with the reference clock, signals are inputted and outputted into and from the digital I/O board232, but this is not essential.

The reference clock circuit230generates the first reference clock signal and the second reference clock signal which are different from each other in the frequency, whereby the first reference clock signal of 1-10 MHz excitation and the second reference clock signal of 0.1-2.0 MHz gradient are generated.

When control signals for controlling the MRI device100are transmitted, the control signals are transmitted in synchronization with the first reference clock, and when measurement signals are received from the MRI device100, the measurement signals are received in synchronization with the second reference clock.

(Operation of the Imaging System)

Next, the operation of the imaging system according to the present embodiment will be described with reference to the functional diagram ofFIG. 2.

In the imaging system according to the present embodiment, images are produced by the MRI device100, based on a measurement program. To execute the measurement program, a pulse sequence file300of pulse sequences described in the text format is prepared.

As shown inFIG. 3, the pulse sequence file300is formed of a plurality of pulse sequences described in the text format.

At the top of the pulse sequence file300, pulse sequences for the initial setting for imaging by the MRI device100are arranged.

For example, they are the pulse sequences in the 1st row to the 11th rows ofFIG. 3.

The 1st row pulse sequence (:NX 1) stipulates a number of accumulations.

The 2nd row pulse sequence (:DW 5) stipulates a receiver sampling rate (microsecond).

The 3rd row pulse sequence (:NR 2048) stipulates a number of receiver sampling points.

The 4th row pulse sequence (:N0 1) stipulates a number of a phase encode 0.

The 5th row pulse sequence (:N1 128) stipulates a number of a phase encode 1.

The 6th row pulse sequence (:N2 16) stipulates a number of a phase encode 2.

The 7th row pulse sequence (:S0 0) stipulates a step size of the phase encode 0.

The 8th row pulse sequence (:S1 64) stipulates a step size of the phase encode 1.

The 9th row pulse sequence (:S2 64) stipulates a step size of the phase encode 2.

The 10th row pulse sequence (:DU 10) stipulates a number of dummy pulses.

The 11th row pulse sequence (:TR 100) stipulates a repetition time TR [mille second].

Pulse sequences of the imaging are arranged, following the pulse sequences of the initial setting. For example, they are the pulse sequences in the 12th row and the row following the 12th row, ofFIG. 3.

The 12th row pulse sequence (00009400 RF 0002) stipulates the transmission of the second RF pulse 9,940 microseconds later from the measurement start.

The 13th row pulse sequence (00010600 GY 8000<-e5) stipulates the renewal and output of a gradient magnetic field GY axis control signal 10,160 microseconds later from the measurement start.

The 14th row pulse sequence (000102200 GX 6E40) stipulates the output of 6E40 to the gradient magnetic field GX axis control signal 10,220 microseconds later from the measurement start.

The 15th row pulse sequence (000102600 GZ 8000<-e6) stipulates the renewal and output of the gradient magnetic field GZ axis control signal 10,260 microseconds later from the measurement start.

The 16th row pulse sequence (000120320 GZ 8000) stipulates the output of 8000 to the gradient magnetic field GZ axis control signal 12,032 microseconds later from the measurement start.

The 17th row pulse sequence (000128260 GY 8000) stipulates the output of 8000 to the gradient magnetic field GY axis control signal 12,826 microseconds later from the measurement start.

The 18th row pulse sequence (000133800 GX 88D4) stipulates the output of 88D4 to the gradient magnetic field GX axis control signal 13,380 microseconds later from the measurement start.

The 19th row pulse sequence (000148800 AD 0000) stipulates the start of receipt by A/D conversion of received signals 14,880 microseconds later from the measurement start.

The 20th row pulse sequence (000302400 GX 8000) stipulates the output of 8000 to the gradient magnetic field GX axis control signal 30,240 microseconds later from the measurement start.

The pulse sequences in from the 12th row to the 18th row, and the 20th row are for operating the MRI device100which is to be controlled.

The pulse sequence in the 19th row stipulates the extraction timing of extracting measurement signals from the MRI device100which is to be controlled.

In the conventional imaging system, as the extraction timing of extracting measurement signals from the MRI device100, an actuation signal is transmitted to an A/D converter (not shown) provided in the MRI device100via a control line separately provided. The pulse sequence in the 19th row indicates the transmission timing of the actuation signal to such A/D converter (not shown).

In the imaging system according to the present embodiment, the A/D converter (not shown) of the MRI device100is kept on, and no control line for the actuation is separately provided. The pulse sequence film ofFIG. 3is for the conventional imaging system. To the contrary, in the present embodiment, the pulse sequence in the 19th row stipulates the extraction timing of extracting a measurement signal form the MRI device100, which is a control device to be controlled.

A pulse sequence generator302which is also referred to herein as pulse signal generator302develops control signals from the pulse sequence file300, and generates a time of starting the extraction of a measurement signal. The pulse signal generator302generates an extraction start time timetable that provides times when measurement signals from the imaging unit of the MRI device are extracted, each of the extraction start, times in the extraction start time timetable being an amount of time that has elapsed from a start of a transmission of the control signals.

(Transmission of Control Signal)

First, the transmission of the control signals will be described.

The pulse sequence generator302develops pulse sequences of the pulse sequence file300stipulating the control of the MRI device100. Control signals are applied for a fixed time interval based on the reference clock and are stored in the control signal buffer304which is the buffer of the timetable of the transmission events.

For example, when the reference clock is 1.0 MHz, as shown inFIGS. 4 and 5, the pulse sequences are developed into control signals of every 1 (one) microsecond (.mu.sec).

To the developed control signals, data number “0” is applied at the start of a measurement operation, i.e., at the start of the transmission of the control signals, and thereafter sequential data numbers “1”, “2”, “3”, . . . are applied. The data numbers of the control signals correspond to a counter N which will be described later.

For example, as shown inFIG. 4, the control signal of data number “0” is “4E18,0000,0000,0000,0000,0000,0000,0000”, the control signal of data number “1” is “4E18,0000,0000,0000,0000,0000,0000,0000”, and the control signal of data number “2” is “4E18,0000,0000,0000,0000,0000,0000,0000”, . . . and the sequentially following control signals are generated.

The respective control signals are segmented, and in the examples ofFIGS. 4 and 5, “4E18” indicates the start of the respective segmented control signals.

The developed control signals are stored in the control signal buffer304. The control signal buffer304is, e.g., the first communication buffer234inFIG. 1.

Based on the data number of each control signal, the time from the start of the transmission of the control signal when the control signal is to be transmitted can be known. For example, as shown inFIG. 4, the control signal having data number “43” is to be transmitted 43 microseconds later after the start of the transmission of the control signal. For example, as shown inFIG. 5, the control signal of data number “14860” is to be transmitted 14860 microseconds later, i.e., 14.86 milliseconds later from the start of the transmission of the control signal.

The control signals stored in the control signal buffer304are sequentially transmitted to the MRI device100, which is the device to be controlled, in synchronization with the reference clock.

Thus, the MRI device100, which is the device to be controlled, is controlled, based on the respective pulse sequence activation of control signal timing of the pulse sequence file300.

Low speed control signals which need not be transmitted via the digital I/O board232are generated by the pulse sequence generator302, stored in the control signal buffer304, decided by a timing judging logic322and transmitted to the MRI device100, which is the device to be controlled.

The general-purpose personal computer200and the computer250can know via the communication interfaces the control signals and also status of all the components of the MRI device100.

The low speed control signals which need not be transmitted via the digital I/O board232are, e.g., a signal that turns on lamps, a signal that changes the transmission/reception gains of the digital transmitter/receiver102, a signal that changes one of filter commands to a lower speed one thereof, and a signal for the control value command of a temperature stabilizer of the magnet, etc.

Between the control signal buffer304and the digital I/O board232, there is a valve324configured for opening and closing with respect to the transmission/reception of the signals.

The valve324is opened and closed by a trigger judging logic326. The trigger judging logic326opens and closes the valve324, taking into account the external synchronization clock circuit240such as heart rate signals, respirations, the power source lock, etc. received via the digital I/O board242, and an external synchronization clock circuit reception timing received from the pulse sequence generator302.

The operation of the valve324is commanded by trigger judging logic326. For example, the command signal data point (000312400 EX 0000) for commanding the operation of the valve324stipulates the closure of the valve32431,240 microseconds later from the start of a measurement and the operation of opening the valve324in accordance with the command of the trigger judging logic326100,000 microseconds later. In this case, the valve324is closed 131,240 microseconds later from the start of the measurement.

A transmitter is configured to transmit the plurality of control signals generated by the pulse signal generator302to the imaging unit of the MRI device via the digital signal input/output in synchronization with the first reference clock signal.

A first storage unit is configured to store the time elapsed from the start of the transmission of the control signals.

Then, the extraction of the measurement signals will be described.

The pulse sequence generator302generates a time of starting the extraction of measurement signals, based on the pulse sequences stipulating the times of extracting measurement signals from the MRI device100of the pulse sequence file300, and stores the times in an extraction start timetable306. The extraction start timetable306is formed by, e.g., the first communication buffer234inFIG. 1.

For example, based on the pulse sequence (000148800 AD 0000) in the 18th row, “14,880 microseconds” is generated as the extraction start time of the measurement signals and, as shown inFIG. 6, is stored in the 1st row of the extraction start timetable306.

In the same way, based on the pulse sequences stipulating the extraction times of extracting measurement signals, times of starting the extraction of the measurement signals are generated and sequentially stored in the extracted start timetable306. Resultantly, the extraction start timetable as exemplified inFIG. 6is generated.

As shown inFIG. 2, the measurement signals from the MRI device100are received by the digital receiver308via the digital I/O board232in synchronization with the reference clock and stored in the measurement signal buffer310.

For example, when the reference clock is 1.0 MHz, as shown inFIGS. 7 and 8, the measurement signals are received every 1 (one) microsecond.

The data number “0” is applied to the measurement signal at the start of the measurement operation, i.e., at the start of the reception of the measurement signals, and thereafter data numbers “1”, “2” and “3”, . . . are sequentially applied to the measurement signals. The data numbers of the measurement signals correspond to a counter “M” is which will be described later.

As exemplified inFIG. 7, the measurement signal of data number “0” is “B1E7,0000,−54,−26,0,1,0000,0000”, and the measurement signal of data number “1” is “B1E7,0000,−54,−21,0,2,0000,0000”, the measurement signal of data number “2” is “B1E7,0000,−54,−16,0,3,0000,0000”. Such sequentially following measurement signals are stored in the measurement signal buffer310.

The respective measurement signals are segmented, and in the examples ofFIGS. 7 and 8, “B1E7” indicates the start of the segmented measurement signals.

Based on the data numbers of the measurement signals, the times of the reception of the measurement signals from the start of the reception of the measurement signals can be known. For example, as shown inFIG. 7, the measurement number (B1E7,0000,−11,−40,0,44,0000,0000” of data number “43” is the measurement signal received after 43 microseconds from the start of the measurement signal reception. For example, as shown inFIG. 8, the measurement signal “B1E7,0000,−6,−30,0,14861,00000000” of data number “14860”, i.e., 14.86 milliseconds is the measurement signal received after 14860 microseconds from the measurement signal reception start.

The filter312shown inFIG. 2extracts measurement signals necessary for the MRI from the measurement signals stored in the measurement signal buffer310, based on the extraction start time stored in the extraction start timetable306, and stores the measurement signal in a measurement data memory314.

For example, in the case of the extraction start timetable306ofFIG. 6, “14,880 microseconds” is stored in the 1st row, the data numbers of the measurement signals stored in the measurement signal buffer310are scanned, and when the data number becomes “14880”, the extraction of the measurement signal starts. Measurement signals are extracted for a certain period of time from the extraction start time “14,880 microseconds”, i.e., up to data number “25115” which is after 5 microseconds.times.2048 points-5 microseconds=10,235 microseconds. That is, when measurement signals have the data numbers from “14880” to “25115”, the measurement signals are extracted.

Subsequently, for “114,880 microseconds” stored in the second row of the extraction start timetable306, the data numbers of the measurement signals stored in the measurement signal buffer310are scanned, and when the data number becomes “114880”, the extraction of the measurement signal is started. And, the measurement signals for a certain period of time from the extraction start time, i.e., after “114,880 microseconds”, i.e., up to data number “125115”. That is, when measurement signals have data numbers “114880”-“125115”, the measurement signal are extracted.

In the same way, based on the extraction start times indicated in the extraction start timetable306, measurement signals are sequentially extracted.

Resultantly, as exemplified inFIG. 9, the measurement data of a certain period of time, e.g., 10,235 microseconds, from the extraction start time “14,880 microseconds”, corresponding to the extraction start times of the extraction start timetable306ofFIG. 6, are extracted. The measurement data of a certain period of time, e.g., 10,235 microseconds, from the extraction start time “114,880 microseconds”, corresponding to the extraction start times of the extraction start timetable306ofFIG. 6, are extracted.

The measurement data stored in the measurement data memory314are subjected to processing of noise removal, image reconstruction, etc. are stored as stored data318in the HDD/SSD memory208or are displayed as an data display320on the personal computer250.

As shown inFIG. 2, into the pulse sequence generator302and the filter312, user's command values can be suitably inputted from the outside.

For example, user's command values are inputted into the pulse sequence generator302from the outside thereby to give information prior to the pulse sequence file300, to command whether or not the external synchronization clock circuit is used, or to command 3-axes rotation angles of the XYZ axes outputs of the gradient magnetic field pulses.

User's command values are inputted from outside into the filter312thereby to command a tap number of the FIR filter, or to command a cut-off frequency, and command other signal processing.

A filter is configured to extract measurement signals with times within a predetermined period of time from when the time of the measurement signal agrees with the time of the extraction start time stored in the extraction start time timetable.

(Measurement Operation Flow of the Imaging System)

Next, the measurement operation flow of the imaging system according to the present embodiment will be described with reference to the flow chart ofFIG. 10.

When a measurement of the imaging system is started, as the initial setting, the counter N and the counter M are reset at 0 (Step S01). The counter N corresponds to the data number of a control signal, and the counter M corresponds to the data number of a measurement signal.

First, it is judged whether or not a control signal transmitted from the control signal buffer304to the digital I/O board232is a measurement finishing signal (Step S02). In the present embodiment, the measurement finishing signal for finishing a measurement is prepared as one control signal.

In Step S02, when the control signal is judged to be the measurement finishing signal, the measurement is immediately finished.

In Step S02, when the control signal is judged not to be the measurement finishing signal, said control signal is transmitted to the MRI device100, which is a device to be controlled (Step S03), and 1 is added to the counter N.

Then, it is judged whether the received signal the digital I/O port232from the MRI device100is a measurement signal (Step S06). The measurement signals are segmented, and “B1E7” indicates the start of the respective segmented measurement signals, and when “B1E7” is detected, said received signal is judged to be a measurement signal.

When the received signal is judged not to be a measurement signal in Step S05, the step is returned to Step S02.

When the received signal is judged to be a measurement signal in Step S05, said received signal is received as a measurement signal (Step S06), and 1 is added to the counter M.

Next, it is judged whether or not the counter M is a measurement signal extraction timing (Step S08).

When the counter M is judged not to be a measurement signal extraction timing in Step S08, the step is returned to Step S02.

When the counter M is judged to a measurement signal extraction timing in Step S08, said measurement signal is extracted (Step S09), and the step is returned to Step S02.

In Step S08, a timing of extracting data from the extraction start timetable306, i.e., a period of time from the measurement start time, and the counter M judges whether or not it is a measurement signal extraction timing.

For example, in the extraction start timetable306ofFIG. 6, as described above, the counter M is from “14880” to “25115”, based on “14,880 microseconds” in the 1st row, the measurement signals are extracted. Based on “14,880 microseconds” in the 2nd row, the counter M is from “114880” to “125115”, the measurement signals are extracted. In the same way, measurement signals are sequentially extracted based on the extraction start times in the extraction start timetable306.

The above-described processing is repeated, and the counter N counts a number of controls signals transmitted to the MRI device100, the counter M counts a number of measurement signals received from the MRI device100, and based on the counter M, the measurement signals are extracted.

As described above, a number of measurement signals from the measurement start time is counted, whereby measurement data can be extracted from measurement signals without separately providing a control line for actuating the A/D converter (not shown) in the MRI device100.

In the present embodiment, the counter N, which counts a number of control signals, and the counter M, which counts a number of measurement signals are separately provided, whereby the count of the control signals and the count of the measurement signals are independently made. This produces the following advantage.

For example, when no measurement signal is detected in Step S05, the counter M is counted up. In this case, a count value of the counter M is smaller than a count value of the counter N, but the processing is correctly carried on.

The reference clock circuit230generates a first reference clock and a second reference clock which are different from each other in the frequency. In synchronization with the first reference clock, control signals are transmitted to the MRI device100. In synchronization with the second reference clock, measurement signals from the MRI device100are received. The counter N counts a number of control signals transmitted in synchronization with the first reference clock. The counter M counts a number of measurement signals received in synchronization with the second reference clock.

The measurement processing of the imaging system of the flow chart described above is one example and is not essential. For example, it is possible that Step S03, Step S06and Step S09are multitasked or multithreaded without obstructing the operation of the measurement to independently operate. Especially, in Step S06, by using vast data stored in Step S06, even after an experiment, data may be collected retrospectively from a time when the experiment finishes to be analyzed. It is possible that a timing of the counter M is changed after an experiment has finished, and measurement signals are extracted. In Step S06, live data of measurement signals may be discarded or preserved.

A receiver is configured to receive measurement signals from the imaging unit of the MRI device via the digital signal input/output unit in synchronization with the second reference clock signal.

A second storage unit is configured to store the measurement signals received in synchronization with the second reference clock signal by the receiver, with a time elapsed from a start of a reception of the measurement signals.

A third storage unit is configured to store the measurement signals within the predetermined period of time extracted by the filter.

EXAMPLE

Sections of an apple were imaged by the imaging system according to the present embodiment. The result of imaging the apple is shown inFIG. 11. As shown inFIG. 11, the present embodiment could provide good images.

The present invention is not limited to the above-described embodiment and can cover other various modifications.

In the present embodiment, the present invention is applied to the imaging system using the MRI device, but this is not essential. For example, the present invention may be applied to imaging systems using X-ray CT devices, supersonic CT devices, PET-CT devices, etc. The present invention may be applied not only to the imaging systems but also to any measuring system, such as semiconductor device steppers, food manufacturing devices, advanced testing devices, machine tools such as NC lathes, etc., configuration shaping measuring devices, 3-dimensional configuration mapping devices, configuration measuring devices, resonance measuring devices, distribution measuring devices, physical measuring devices, distribution observation devices, etc.

In the above-described embodiment, a user prepares the pulse sequence file in advance, but this is not essential. For example, the data processing unit316automatically generates a pulse sequence file to realize an optimum operational state of the device100to be controlled. In this case, the application scope of the present invention is not limited to the devices described above. The present invention may be applied to the automatic driving devices of cars, aircraft, etc.

In the specification of the present application, “measurement” includes any measurement, such as imaging objects, measurement of configurations of objects, detection of objects, measurement and detection of characteristics of objects, measurement of physical quantities, detection of physical quantities, etc.

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