Patent Publication Number: US-2012035455-A1

Title: Initiating a Scan in a Medical Imaging System

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority from a U.S. Provisional Patent Application No. 60/843,469 filed on Sep. 7, 2006. The disclosure of that application is incorporated herein by reference. 
    
    
     BACKGROUND 
     This disclosure relates to a communication device for use in a medical imaging system. 
     During magnetic resonance imaging (MRI) and computed tomography (CT) scanning procedures, it is often necessary to provide the patient in an MRI or CT machine with instructions or information regarding a scan procedure. For example, in certain circumstances, it is desirable to instruct a patient to hold their breath and remain still so that acceptable scans can be obtained. To facilitate this, some machines utilize software driven voice command systems which audibly instruct patients to hold their breath for precisely timed periods in preparation for one or more scans. Following delivery of the instruction, the automated system initializes the scan. However, it is often the case that a patient is not ready once the scan begins. Subsequently, motion artifacts may appear in the resulting scan image, thus requiring the scan to be repeated. Repeating scans is time-consuming and results in increased hospital costs as well as increased patient stress. 
     SUMMARY 
     Various aspects of the invention are set forth in the claims. 
     For example, in one aspect, an apparatus for use in a medical imaging system includes a magnetically and radiographically inert communication device, a sensor coupled to the communication device and a processor coupled to the sensor. The processor is operable to initiate a scan by the medical imaging system upon activation of the communication device. 
     In another aspect, a method of initiating a scan in a medical imaging device includes detecting a patient-ready signal from a magnetically and radiographically inert communication device and automatically initiating the scan upon detecting the patient-ready signal. 
     Some implementations include one or more of the following features. For example, the communication device can be hand-held. In some cases, the sensor is operable to detect a patient-ready signal that is generated by the communication device. 
     In some implementations, the detection of the patient-ready signal includes detecting a change in air pressure or an absolute pressure level. The communication device can include a pneumatic actuation device. In addition, the apparatus can include a pneumatic coupler coupled to the communication device and to the sensor. In some cases, the sensor includes a pressure sensor that can detect a change in pressure or an absolute pressure level. 
     In some implementations, detection of the patient-ready signal includes detecting an optical signal or a change in an optical signal. For example, the optical signal can include a polarization state of the optical signal or a change in light intensity. The communication device can include an optical switch. Alternatively or in addition, the communication device may include a polarizer. In another example, the apparatus includes an optical waveguide, in which the optical waveguide is coupled to the communication device and the sensor. In some cases, the apparatus includes an optical transmitter and/or an optical detector which can detect changes in light intensity. In some cases, the optical detector can detect a change in a polarization state of light. 
     In some implementations, automatically initiating the scan includes modifying the patient-ready signal to be compatible with the medical imaging device and transmitting the modified patient-ready signal to the medical imaging device. Other features and advantages will be apparent from the detailed description and drawings, and from the claims. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  illustrates an example of an imaging system. 
         FIG. 2  illustrates an example of a hand-held communication device. 
         FIG. 3  illustrates an example of a hand-held communication device. 
     
    
    
     DETAILED DESCRIPTION 
     MRI imaging and CT scans are useful diagnostic tools that enable non-invasive analysis of internal structures and flows within a patient&#39;s body. Generally, MRI entails the application of radio frequency waves to a patient&#39;s body in a region of changing magnetic field such that the molecules within the patient&#39;s body resonate at detectable frequencies. The detected frequencies are processed to enable imaging of internal and external structures. CT scanning entails the generation of a three-dimensional image of a patient&#39;s internal structures from a large series of two-dimensional X-ray images taken around a single axis of rotation. 
     One common application of MRI and CT scanning is in breath-hold imaging studies, which can be very important in medicine and medical research. Breath-hold imaging is a technique in which the patient holds his breath during one or more imaging scans. By holding his breath, the patient minimizes respiratory movement that can cause image artifacts in abdomen and thoracic imaging procedures. Breath-hold imaging requires the full cooperation of the patient as the scan time can extend from  15  to  20  seconds in duration. In some cases, it is necessary for a patient to practice breath holding outside the scanner so that they can improve their response during the examination. However, in many instances, image degradation due to respiratory motion or movement from the patient remains a significant problem because of the length of time necessary to acquire image data. These problems are exacerbated in automated imaging systems that begin scanning when a patient is not ready or is still moving. 
       FIG. 1  shows an example of an imaging system  1  which includes a communication device  5  to allow a patient  9  to signal readiness for a scanning procedure to begin. The system  1  includes a MRI machine  3  into which the patient  9  enters. In some implementations, a CT scan machine is used in place of the MRI machine  3 . After entering the machine  3 , an automated program within the system  1  audibly or visually may request the patient  9  to indicate that they are prepared for the scanning to begin. When the patient  9  is ready, the patient activates the device  5  in response to the request such that a patient-ready signal is sent to a sensor  7  coupled with the device  5 . Upon receiving and detecting the patient-ready signal, the sensor  7  outputs a data signal to the MRI machine  3  to activate the scanning procedure. The output of the sensor  7  can be any data signal that is compatible with a scanning device. For example, in some cases, the sensor  7  modifies the patient-ready signal such the data signal output by the sensor  7  corresponds to an ASCII text data, a TTL voltage signal, or an optical signal. Other signal formats and types may be used as well. 
     Preferably, the communication device  5  is a hand-held device with a simple activation mechanism  6  such as, for example, a push-button or switch. In addition, the device  5  should be formed from non-ferrous, magnetically inert and radiographically inert materials that do not interact with the high magnetic fields of the MRI machine  3  or the X-rays of a CT scanner. Similarly, the patient-ready signals generated by the communication device  5  also should not interact with the high magnetic fields generated by the MRI machine  3  or X-rays generated by a CT scanner. 
       FIG. 2  shows an example of a hand-held communication device  5  in a first embodiment that utilizes pneumatic action. The device  5  includes as the activation mechanism  6  a pliable mushroom cap that, when depressed, causes a change in air pressure within the device  5 . The device  5  is coupled to a conduit  11 , such as a pneumatic tube, that transfers the change in air pressure to a pneumatic sensor  13 . The pneumatic sensor  13  can be any type of pressure sensor or pressure-differential sensor that is able to detect absolute pressure or changes in air pressure caused by activation of the device  5 . The sensor  13  is coupled to a processor  15  which is responsible for initiating the image scanning and activation of the machine  3 . Upon detecting the change in air pressure or upon detecting a desired air pressure level, the sensor  13  generates and sends a signal, such as an electric potential or current, to the processor  15 . After receiving the signal, the processor  15  then activates the image scanning procedure. In some implementations, the pneumatic sensor  13  is combined with the processor  15  as part of a computer. Alternatively, the sensor  13  is a separate component which can be coupled to or removed from a computer that includes the processor  15 . In some cases, the sensor  13  is directly coupled to the machine  3  such that the signal provided by the sensor  13  initiates the scan. 
     Other mechanisms for generating a change in air pressure also may be used. For example, the pliable mushroom cap can be replaced with a plunger mechanism that, when depressed, increases the pressure within the device  5 . This increase in pressure then can be transmitted along the pneumatic tube  11  to the sensor  13 . 
     In another embodiment, the hand-held communication device  5  generates a patient-ready signal by interrupting an optical communication link as shown, for example, in  FIG. 3 . In that example, a transceiver  17  generates an optical signal that is transmitted along an optical path to the communication device  5  by means of a waveguide  21 , such as an optical fiber. The optical signal then travels back from the device  5 , also by means of the waveguide  21 , and is detected by the transceiver  17 . The optical signal can be generated using components such as a light emitting diode or laser diode whereas detection can be accomplished using components such as a photodiode or solar cell. Other components for optical generation and detection may be used as well. The optical generation and detection components can be integrated on a single device or used as separate discrete devices. Furthermore, the optical waveguide  21  can include either a single waveguide or separate waveguides for transmission and detection of the optical signal. 
     When the communication device  5  is in an inactive state, there is no interruption in the optical path and the transceiver  17  outputs a signal to the processor  15  indicating that the patient is not ready for the scan to begin. The signal sent to the processor  15  can include, for example, a fixed voltage or electric current. Upon activation of the device  5 , however, the optical path is interrupted and the transceiver  17  no longer detects light from the waveguide  21 . Accordingly, the output signal from the transceiver  17  changes state to indicate that the patient is ready for the scan to begin. The output signal from the transceiver  17  can include, for example, a voltage or current level that is substantially different from the signal output by the transceiver  17  when the device has not been activated. The processor  15  coupled to the transceiver  17  detects the change in output signal and initiates the scan. Alternatively, the transceiver  17  can be coupled directly to the machine  3  such that the transceiver output signal initiates the scan. 
     In another implementation, the optical path can be restored upon activation of the communication device  5 . For example, when the device  5  is in an inactive state, it may block transmission of light to the receiver portion of the transceiver  17 . When the patient activates the device  5 , however, the optical path is restored and an optical signal is delivered to the transceiver  17 . 
     Various different mechanisms can be used to interrupt the optical path. In some implementations, the communication device  5  includes a mechanical optical switch that, depending on activation or deactivation of the device  5 , deflects or absorbs the light in the optical path. For example, the device  5  can include a lens in the optical path that translates or rotates to a different position when the patient depresses the push button  6  on the device  5 . Depending on the direction of translation/rotation, the optical signal will either travel through the waveguide  21  and return to the transceiver  17  or will be refracted away from the transceiver  17 . Similarly, the lens can be replaced with a mirror that also can be translated or rotated. For example, when the device  5  is inactive, the mirror, in a first state, is operable to reflect incoming light back to the transceiver  17 . Upon activation of the device  5 , the mirror can be rotated or repositioned to a second state such the light is no longer reflected back to the transceiver  17 . 
     In another implementation, activation of the communication device  5  alters the state of the optical signal as opposed to interrupting the optical path. For example, the communication device  5  can include a polarizer that, upon activation of the device  5 , changes the polarization of the light traveling along the optical path. Upon detection of the change in polarization, the transceiver  17  outputs a signal indicating that the patient is prepared for the scan to begin. 
     A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other implementations are within the scope of the claims.