Abstract:
A method and apparatus to improve the efficiency of an MRI apparatus by allowing the controller of the MRI to be remotely reconfigured, allowing modification and upgrade of the hardware configuration of the controller. For complex or innovative pulse sequences, a customized hardware configuration of the controller may be necessary; for optimization of digital signal processing of the received data, reconfiguring the hardware configuration of the controller to perform the digital signal processing may be desirable.

Description:
This application claims the benefit of Provisional Application No. 60/317,450 filed Sep. 7, 2001. 
    
    
     TECHNICAL FIELD 
     The present invention is directed to magnetic resonance imaging (MRI) devices, and, particularly, to an improved technique for reconfiguring MRI devices. 
     BACKGROUND OF THE INVENTION 
     MRI technology permits the noninvasive imaging of internal details within an object, such as a living person. The scientific and diagnostic values of this technology are set forth in numerous prior art patents and articles, e.g., the many innovations of Dr. Raymond V. Damadian, the discoverer of this technology, as noted in the patent records. 
     Magnetic resonance imaging, also called nuclear magnetic resonance (NMR) imaging, is a non-destructive method for the analysis of materials and is used extensively in medical imaging. It is completely non-invasive and does not involve ionizing radiation. In very general terms, nuclear magnetic moments of individual atoms within a portion of a body are excited at specific spin precession frequencies which are proportional to the local magnetic field. The radio frequency (RF) signals resulting from the precession of these spins are received using pickup coils. By manipulating the magnetic fields, an array of signals is provided representing different regions of the volume. These are combined to produce a volumetric image which characterizes the nuclear spins within the body. 
     In MRI, a body is subjected to a constant magnetic field. Another magnetic field, in the form of electromagnetic (RF) pulses, is applied orthogonally to the constant magnetic field. The RF pulses have a particular frequency that is chosen to affect particular atoms (typically hydrogen) in the body. The RF pulses excite the atoms, increasing the energy state of the atoms. After the pulse, the atoms relax and release RF emissions, corresponding to the RF pulses, which are measured and displayed. 
     At the heart of an MRI device is a controller, which controls the pulse sequences, retrieves and stores the relaxation emissions, and sends this data to a computer which processes and displays the data. The controller may be a complex programmable logic device (CPLD), which includes a series of embedded array blocks (EABs) used to implement various memory and complex logic functions, as is understood to those skilled in the art. The respective EABs are physically configured in a desired manner to eliminate the need for discrete chips. The controller might also be another type of programmable logic device, such as a field programmable gate array (FPGA) or application specific integrated circuit (ASIC). It should also be understood that CPLD, FPGA, and ASIC boards are statically configured, ie., the board is so configured and stays so configured during the lifetime of use. 
     As noted, the hardware in present MRI systems is fixed. In particular, either the hardware is made of discrete logic or the respective CPLDs, FPGAs, ASICs, etc. that constitute the boards are physically configured and remain that way thereafter until obsolete. 
     Thus, in prior art techniques, the hardware is only designed to enable a generic MRI sequence run. Any newly-created sequence runs must, therefore, be designed to run on the generic configuration even if that configuration is inefficient or incorrect. 
     There is, therefore, a present need for an improved system and methodology for ameliorating or eliminating the inefficiencies in prior art MRI techniques, enabling MRI operators to readily reconfigure the hardware for a variety of potential sequences and hinder device obsolescence. 
     SUMMARY 
     The present invention provides a method and apparatus to improve the efficiency of an MRI apparatus by allowing the controller of the MRI to be remotely reconfigured, allowing modification and upgrade of the hardware configuration of the controller. For complex or innovative pulse sequences, a customized hardware configuration of the controller may be necessary; for optimization of digital signal processing of the received data, reconfiguring the hardware configuration of the controller to perform the digital signal processing may be desirable. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings where: 
     FIG. 1 illustrates various components of an MRI machine; 
     FIG. 2 illustrates a flowchart showing the development of a new sequence for a statically-configured MRI controller; 
     FIG. 3 illustrates a flowchart showing the development of a new sequence for a reconfigurable MRI controller in accordance with an embodiment of the present invention; 
     FIG. 4 illustrates a flowchart showing the conventional operation of an MRI machine; 
     FIG. 5 illustrates a flowchart showing the conventional operation of an MRI machine performing digital signal processing; and 
     FIG. 6 illustrates a flowchart showing the operation of a reconfigurable MRI machine according to the principles of the present invention performing digital signal processing. 
    
    
     DETAILED DESCRIPTION 
     The following detailed description is presented to enable any person skilled in the art to make and use the invention. For purposes of explanation, specific nomenclature is set forth to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art that these specific details are not required to practice the invention. Descriptions of specific applications are provided only as representative examples. Various modifications to the preferred embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the scope of the invention. The present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest possible scope consistent with the principles and features disclosed herein. 
     A Magnetic Resonance Imaging (MRI) apparatus is shown in FIG. 1, and generally designated by the reference numeral  100 . The MRI apparatus  100  has a bed  102 , where the object being examined is placed. The object may be a physical culture, a person, an animal, or any other physical object, as is understood in the art. The bed  102  is surrounded by magnetic coils, generally designated by the reference numerals  104 , which generate the constant magnetic field, as described above. 
     With further reference to FIG. 1, there is illustrated an MRI controller  106  for controlling an RF signal generator  108  that creates the RF pulses that excite the atoms of the object being examined. As is understood in the art, the controller  106  receives and stores the information from an RF coil  110  that receives the relaxation RF signals from the atoms in the object. Typically, the atoms are hydrogen atoms, but, as is understood in the art, may be any other atom having appropriate characteristics. With further reference to FIG. 1, the MRI apparatus  100  is connected to a computer  112  processes the data received from the controller  106  and displays the information on a monitor  114 . 
     In a conventional MRI apparatus, the MRI controller  106 , which generates the pulse sequence, receives the relaxation signals, and sends the data to the computer  112  for processing and display of the information, is a system that consists of statically-configured logic devices, such as a CPLD, FPGA, ASIC, etc. 
     As noted, the prior art conventions and practices employ static hardware, and those utilizing such devices learn to work around the hardware configurations to achieve their objectives, if able. In the present invention, however, the MRI controller  106  is a reconfigurable logic device that may be reprogrammed remotely, without removal of the board from the physical MRI apparatus. This constitutes a paradigm shift in operating an MRI and fulfills a long-standing and long-felt need in this industry. The MRI controller  106  may, for example, be connected to the computer  112  by a cable  116  such that the user may load a new hardware configuration for the controller  106  onto the computer  112  and then later download the new hardware configuration onto the controller  106 . 
     With respect now to FIG. 2, a conventional method of developing a new sequence is illustrated, referring for reference to the MRI apparatus  100  shown in FIG. 1, in which the MRI apparatus  100  configuration is, in this instance, static. First, a new pulse sequence is developed that facilitates a more efficient MRI scanning technique (step  210 ). The pulse sequence may be designed to more effectively utilize a specific scanning technique, such as T1-weighted, T2-weighted, or balanced T1- and T2-weighted scanning, as are already well-known in the art, as well as other and more sophisticated pulse sequences made possible in this new paradigm of operation. 
     The pulse sequence may also be designed to more effectively utilize any scanning technique, such as by increasing the overall signal-to-noise ratio or by requiring less power. Next, the new pulse sequence is optimized to run on the existing MRI controller configuration (step  220 ). As discussed, innovative and complex pulse sequences may need to be significantly redesigned in order to run on an existing configuration that is geared for generic pulse sequences. In order to run optimally on such existing and statically-configured systems, the effectiveness of the new pulse sequence may be reduced, or the new pulse sequence may need to be modified to run incorrectly for purposes of compatibility. After the pulse sequence has been thus “optimized” for the hardware controller  106  of the MRI apparatus  100 , the new sequence is loaded onto the MRI apparatus  100  (step  230 ) and the new sequence is used in operation (step  240 ). 
     It should, of course, be understood that one skilled in the art of pulse sequence optimization may apply steps  210  and  220  simultaneously. Steps  210  to  240  are illustrative only of the complicated and time-consuming process of pulse sequence design. 
     According to a preferred embodiment of the present invention, the MRI apparatus has a remotely-reconfigurable MRI controller  106 . A method of developing a new pulse sequence for use on the reconfigurable MRI apparatus  100  is shown in FIG.  3 . First, a new pulse sequence is developed (step  310 ), as described above. Specifically, the pulse sequence may be designed to more effectively utilize a specific scanning technique, such as T1-weighted, T2-weighted, balanced T1- and T2-weighted scanning, or more sophisticated pulse sequence designs, or may be designed to more effectively utilize any scanning technique, such as by increasing the overall signal-to-noise ratio or by requiring less power. Next, the hardware configuration of the controller  106  is redesigned to optimally run the new pulse sequence (step  320 ). As discussed, complex or newly-designed pulse sequences may not operate efficiently or correctly on a generically-configured controller  106  and may require a custom design for the configuration of the controller  106 . The new pulse sequence, contoured to optimize operations, is loaded onto the MRI controller  106  and the new hardware configuration is downloaded to the MRI controller  106  (step  330 ). The download may be in response to a separate reconfigure command, or the reconfigure command may be the same as the download. The new sequence is then used in operation (step  340 ). 
     In another embodiment, the MRI controller  106  is optimally reconfigured to facilitate digital signal processing. Signal processing algorithms, such as filtering, decimation, summing, etc., may be performed on the MRI apparatus  100  by reconfiguring the hardware of the MRI controller  106 . The appropriate hardware configuration is loaded onto the MRI controller  106  before the MRI scan is started. With reference now to FIGS. 4 to  6  of the Drawings, the effect of reconfiguring the controller  106  to improve digital signal processing is shown. 
     The operation of an MRI apparatus  100  with a conventional, statically-configured controller  106  is shown in FIG. 4, and designated therein by reference numeral  400 . An initial generic hardware configuration A of the MRI controller is downloaded to the controller  106  (step  401 ). Alternately, the MRI controller  106  may be a statically-configured controller  106  already having the generic hardware configuration A. In either case, the generic configuration A is designed to perform the generic controller functions optimally. The generic configuration A is not designed to perform specialized functions such as digital signal processing on the received data. Also, a pulse sequence is loaded onto the MRI controller  106  (step  403 ). This pulse sequence may be any conventional or customized pulse sequence. It should, of course, be understood that different controllers have different generic hardware configurations pursuant to their manufacturer. 
     With reference again to FIG. 4 of the Drawings, after the hardware configuration and pulse sequence are loaded into the MRI controller, the MRI scan can begin. The controller  106  generates waveforms (step  405 ), and the signal generator  108  produces digitizing pulses therefrom. The data from the digitizing pulses, e.g., echo, spectroscopic, free induction decay and other signals, is received and sent to the MRI controller  106  for storage (step  407 ), then sent to the computer  112  (step  409 ). For illustrative purposes only, echo data is shown in FIG.  4 . On the computer  112 , software reconstruction of the echo or other data produces useful image data that reconstructs the physical information observed by the MRI machine (step  411 ) and displays the image data in a visual format on a display screen or monitor  114  (step  413 ). 
     The operation of the MRI apparatus  100  with the generic hardware configuration of the controller  106  (as shown in FIG. 4) and with additional signal processing done in software is shown in FIG. 5, the steps for which being designated by reference numeral  500 . Similar to the operation shown in FIG. 4, a generic hardware configuration A is downloaded to the MRI controller  106  (step  501 ). Again, the hardware configuration A may alternately be pre-existing on the MRI controller  106 , rather than downloaded to the controller  106 . The pulse sequence is also loaded onto the MRI controller  106  (step  503 ). As above, the pulse sequence may be any conventional or customized pulse sequence. 
     Similar to the operation shown in FIG. 4, after the hardware configuration and pulse sequence are loaded into the MRI controller  106 , the MRI scan can begin, and the controller  106  generates waveforms (step  505 ), and the signal generator  108  produces the requisite digitizing pulses. First echo data  1  from the digitizing pulses is received and sent to the MRI controller  106  for storage (step  507 ), and second echo data  2 , from a different set of scanning parameters is received and sent to the MRI controller  106  for storage (step  509 ). The echo data  1  and  2  are then sent to the computer  112  (step  511 ). As discussed, spectroscopic, free induction decay and other data may alternatively be utilized. 
     On the computer  112 , the echo data  1  and  2  are summed in a software application (step  513 ). After the data is digitally processed, the echo data is reconstructed in software to produce useful image data that reconstructs the physical information observed by the MRI machine (step  515 ). This image data is then displayed in a visual format on a display screen or monitor  114  (step  517 ). 
     The operation of an MRI apparatus  100  reconfigured to perform signal processing is shown in FIG.  6  and designated therein by reference numeral  600 . An initial custom hardware configuration B of the MRI controller  106  is downloaded to the controller  106  (step  601 ). The custom hardware configuration B may be designed to optimally run a particular pulse sequence, or may be generically designed to run a variety of pulse sequences. The hardware configuration B is optimally designed to perform digital signal processing on the received data. In this case, the hardware configuration B is designed to perform a summing function on the received data, but the hardware configuration may be designed to perform any digital signal combination, singly or in combination, including decimation, filtering, etc. A pulse sequence, which may be a particular pulse sequence optimized by the MRI controller  106  or may be any pulse sequence, is loaded onto the MRI controller  106  (step  603 ). 
     Similar to the operation shown in FIG. 5, after the hardware configuration and pulse sequence are loaded into the MRI controller  106 , the MRI scan can begin, the controller  106  generates waveforms (step  605 ), and the signal generator  108  produces digitizing pulses. First echo data  1  from the digitizing pulses is received and sent to the MRI controller  106  for storage (step  607 ), and second echo data  2 , from a different set of scanning parameters is also received and sent to the MRI controller for  106  storage (step  609 ). When both echo data  1  and echo data  2  are received at the MRI controller  106 , the MRI controller  106  performs a digital signal processing function on the received data (step  611 ). In this example, the echo data  1  and the echo data  2  are summed on the MRI controller  106 , before the resultant data is then sent to the computer  112  (step  613 ). 
     As in the operation shown in FIGS. 4 and 5, after the data is digitally processed, the echo data is reconstructed in software to produce useful image data that reconstructs the physical information observed by the MRI machine (step  615 ). This image data may then be displayed in a visual format on a display screen or monitor  114  (step  617 ). 
     As discussed, echo data has been used illustratively, and other types of data may be employed, as are well understood to those skilled in the art. 
     Performing the digital signal processing function on the MRI controller  106  rather than in a software application has several advantages. When the data is summed on the computer  112  rather than the controller  106 , twice as much data is sent to the computer  112  than if the data is summed on the controller  106  before sending the data to the computer  112 . Also, when the data is summed on the computer  112 , the summation cannot begin until all echo data is received on the computer  112 , which is slower than performing the summation with only part of the data received. 
     The foregoing description of the present invention provides illustration and description, but is not intended to be exhaustive or to limit the invention to the precise one disclosed. Modifications and variations are possible consistent with the above teachings or may be acquired from practice of the invention. Thus, it is noted that the scope of the invention is defined by the claims and their equivalents.