Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R33/00—Arrangements or instruments for measuring magnetic variables
  • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
  • G01R33/44—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
  • G01R33/48—NMR imaging systems
  • G01R33/483—NMR imaging systems with selection of signals or spectra from particular regions of the volume, e.g. in vivo spectroscopy
  • G01R33/4833—NMR imaging systems with selection of signals or spectra from particular regions of the volume, e.g. in vivo spectroscopy using spatially selective excitation of the volume of interest, e.g. selecting non-orthogonal or inclined slices
  • G01R33/4835—NMR imaging systems with selection of signals or spectra from particular regions of the volume, e.g. in vivo spectroscopy using spatially selective excitation of the volume of interest, e.g. selecting non-orthogonal or inclined slices of multiple slices

Definitions

• the present invention relates to an NM-R imaging device with an improved data acquisition device that helps to speed up image reconstruction.
• a conventional NMR imaging apparatus is configured such that a static magnetic field coil 2 which is energized by a power supply * driver 1 to form a uniform and stable static magnetic field and a power supply RF pulse is generated, and the NMR signal of the subject is detected and supplied to the preamplifier ⁇ detector 3 and supplied to the probe head (RF coil) 4, and the power supply ⁇ driver 1 activates X, y, z 3
• a gradient E magnetic field coil 5 that forms a linear gradient magnetic field in the direction and superimposes it on the static magnetic field
• an AZD converter ⁇ 4 that converts the output signal of the Preamplifier ⁇ Detector 3 and computer system 6 that controls AZD converter 14 and processes digital data supplied from AZD converter 14.
• the computer system 6 includes a central processing unit (CPU) 1, a sequence controller 8, an image display unit (CRT) 9, a memory (DISK) 10, an array processor (AP) 11 with high-speed memory, and an input / output device (1 No. 0) 12 are connected by a system bus 13, and an A / D converter 14 is connected to 1/102.
• CPU central processing unit
• sequence controller 8 an image display unit
• DISK memory
• AP array processor
• Fig. 5 shows a schematic diagram of the relationship between slices and views.
• 15 indicates the object
• m indicates the number of slices
• n indicates the number of views.
• k samples of data are collected in one measurement, and such measurements are performed j times on the weekly view to average the measurement data.
• the number of slices m is 2
• the number of views n is 256
• the number of sample data k is 256
• the number of measurements for averaging j it is assumed that the number of slices m is 32 and the number of measurements j for averaging is 8 in an actual apparatus.
• the sequence controller 6 drives the power supply ⁇ driver 1 at a certain timing based on the command from the CPU 7, the RF excitation of the probe head 4 and the current of the gradient magnetic field coil 5 required for NMR signal measurement are turned on ⁇ off. Is executed. Prior to this, it goes without saying that a uniform and stable static magnetic field is formed by the static magnetic field coil 2.
• the NMR signal received by the probe head 4 is base-band-converted to an audio frequency by a preamplifier ⁇ detector 3 and then supplied to an AZD converter 14.
• Fig. 6 (a), (b), (c) and (d) show the timing of the RF excitation of the probe head and the application of the gradient magnetic field in each of the X, y, and z directions.
• an NMR signal shown in FIG. 6 (e) for example, a free induction signal (FID signal) is detected.
• NMR signals E m (# n, j) is collected in FIG. 7 A ⁇ accordance sensible number of detected indicate the order is stored in the D ISK10 order parentheses.
• the measured value of the NMR signal E m (#n, j) consists of k sample data.
• the order of the data stored in DI SK10 is such that the first measurement data of a view is arranged in the order of slices, and then the second measurement data of the same view is arranged in the slice number. Is to be repeated for each view. As a result, the measurement data becomes complicated for the slice, and the data of the same slice does not exist as one.
• the CPU 7 uses the first data E ⁇ (# 1,1) and the second data ⁇ (# 1, 2) of slice 1 and view 1 for the data stored in this way, 1) + ⁇ ⁇ (# 1,2) ⁇ / 2 and restore the average value ⁇ (# 1) to DI SK 0 as raw data of view 1 of slice 1.
• the CPU 7 performs a similar averaging operation on all the views in each slice, and stores the average value in the DISK 10 secondarily. Therefore, the averaged raw data E (# 1), E 2 (#D. To E (# 256), E 2 (# 256) are restored in DI SK10 with the order shown in Fig. 7 B Even in this state, the data array is still complicated with respect to the slice.
• select c from the data stored in such a state.
• PU 7 collects the data E (# 1), ⁇ ( ⁇ , (# 256) for slice 1 if it collapses, as shown in column C of FIG. performing image reconstruction of the slice 1 Ri. when the reconstructed image to reconstruct the. image slices 2 to be displayed on CRT9 is one data ⁇ (# 1), ⁇ 2 (# 2), ⁇ For 2 (# 256), the CPU 7 and # 11 perform similar processing.
• measurement data is stored in a large-capacity memory in a complicated state with respect to slices in accordance with the collection reference, and such data is stored at the time of image reconstruction. Since the raw data for each slice is picked up from inside and image reconstruction is performed, the burden of ⁇ 117 is increased, and the speed of image reconstruction is reduced.
• a raw data memory (18) that can store raw data for a maximum number of slices collected in one scan, which is different from a computer-based memory, is sequentially provided according to a sequence of a multi-slice multi-echo method.
• the raw data memory ( ⁇ 8) It is characterized in that a data block is formed for each slice.
• FIG. 1 is a configuration diagram showing one embodiment of the present invention
• FIG. 2A shows a measurement sequence of an NMR signal in one embodiment of the present invention
• FIGS. 2B and 3 show a memory map showing the storage state of raw data
• FIG. 4 is a configuration diagram showing a conventional example
• FIG. 5 is an illustration of data collection by the multi-slice method
• FIG. 6 is a diagram illustrating a sequence of NMR signal measurement by the multi-slice method
• FIG. 5 is an illustration of data collection by the multi-slice method
• FIG. 6 is a diagram illustrating a sequence of NMR signal measurement by the multi-slice method
• FIG. 6 is a diagram illustrating a sequence of NMR signal measurement by the multi-slice method
• FIG. 1 is a configuration diagram showing one embodiment of the present invention.
• Reference numeral 16 denotes a data collection device including an A / D converter 14, an averager 17 for averaging the output data of the AZD converter 14, a raw data memory 8 to which the output data of the averager 17 is given, and And an address converter 19 for providing an address signal to the averager 17 and the raw data memory 18.
• the address converter 19 converts an address for storing the output data of the AZD converter 14 in the raw data memory 18 so that the data arriving in a complicated state with respect to the slice is stored in the raw data memory 18.
• the data is stored in the provided area for each slice according to the slice number of the data.
• the AZD converter 14, averager 17, and address converter 19 are controlled by the sequence controller 8.
• the data in the raw data memory 18 is transferred to DISK10 through IZ012.
• the number of slices m in the subject is 2
• the number of views ⁇ is 256
• the number of sample data k is 256
• the number of measurements j for averaging is 2 as in the case of FIG.
• the sequence controller 8 drives the power supply ⁇ driver 1 in the same manner as in the conventional example. That is, the following operations (a) to (e) are performed.
• the above operation generates an NMR signal as shown in FIG.
• the detected NMR signal is digitized by the AZD converter 14.
• the data sequence is converted into the data sequence shown in Fig. 2A (b), that is, E (# 1,1), E 2 (# 1,1), E 1 (# 1,2), Eo (# 1,2 ) ... is given to the averager 17.
• the averager 17 outputs the data as it is when the first measurement data for averaging is acquired and writes it to the raw data memory 18.
• the measured data is read out from the raw data memory 18, and the average is calculated and output.
• Such an operation of the averaging device 17 is executed under the control of the sequence controller 8.
• the address for writing and reading the measurement data is provided from the address converter 19. Therefore, when the data E (# 1,1) and E 2 (# 1,1) are taken into the class averager 17 by the operations (a) and (b), they are output as they are. is based on the address which the address converter 17 specifies, as Figure 2B, one data ⁇ in the data area for the slice 1 for the data area in the data E ⁇ (# 1) address and slice 2 (# 1) are stored in the respective addresses.
• the averaging unit 17 periodically fetches the data from each region.
• previous data ⁇ ⁇ (# 1,1) and E n (# 1,1) uptake also, ⁇ E ⁇ (# 1, D + E 1 (# 1,2) ⁇ 2 and, ⁇ E 2 (# 1,1) + E 2 (# 1,2) ⁇ Average calculation of 2 and outputs the result, and based on the address specified by the address converter ⁇ 9, these output data are used for slice 1.
• the raw data memory 18 does not need to have a storage area for each of the plurality of measurement data for averaging. It is only necessary to have a capacity capable of storing data for the scan.
• the data in the raw data memory 18 is transferred to and stored in the DISK 10 after the completion of one scan, while maintaining the data array organized for each slice as described above.
• the AP 11 reads out data necessary for image reconstruction from an area where data relating to a desired slice is stored, and performs predetermined processing. The reading of data at this time is efficiently executed because the data necessary for image reconstruction is scattered in the area of each slice, and thereby the image reconstruction can be performed at high speed.
• the present invention does not limit the number of views, the number of slices, and the order of data collection to those described above.

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• Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Spectroscopy & Molecular Physics (AREA)
• High Energy & Nuclear Physics (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• General Physics & Mathematics (AREA)
• Magnetic Resonance Imaging Apparatus (AREA)
• Image Processing (AREA)
• Controls And Circuits For Display Device (AREA)
• Image Analysis (AREA)
• Medical Treatment And Welfare Office Work (AREA)

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• 1985
  • 1985-06-13 JP JP60128896A patent/JPS61286741A/ja active Granted
• 1986
  • 1986-06-12 DE DE8686903595T patent/DE3687218T2/de not_active Expired - Fee Related
  • 1986-06-12 WO PCT/JP1986/000294 patent/WO1986007460A1/ja not_active Ceased
  • 1986-06-12 US US07/023,558 patent/US4733187A/en not_active Expired - Fee Related
  • 1986-06-12 EP EP86903595A patent/EP0224597B1/en not_active Expired - Lifetime

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