Abstract:
This method for analysing the sounds of body fluid flows includes:—simultaneously acquiring ( 2 ) sounds from various locations of a body;—identifying ( 6 ) the points of maximum sound intensity (PMIs) of the acquired sounds for each acquisition instant;—determining ( 10 ) the source locations of the acquired sounds; and—determining ( 12, 14 ) the sound radiation patterns of the acquired sounds. A corresponding device, system and program perform this method.

Description:
FIELD OF THE INVENTION 
     The present invention concerns a method, a device and a system for analysing the sounds of body fluid flows. 
     In several organs of bodies, such as the human body, the fluid flows have distinctive sounds characteristics and the knowledge of those sounds characteristics provides important information to physicians for establishing diagnosis. 
     For example, heart murmurs or abnormal heart sounds are caused by turbulent blood flow through narrow or abnormally functioning valves. 
     BACKGROUND OF THE INVENTION 
     Several existing techniques allow to acquire sounds from various locations of the body and to analyse them. This is the case for example in the patent document U.S. Pat. No. 6,699,204-B1 
     However, the existing techniques focus on identifying the location of the origins of sound but fail to analyse other important distinctive characteristics. 
     More precisely, an important sound characteristic is the radiation of the sounds. To illustrate, a murmur of aortic stenosis would originate in the second interspace on the right of the sternum and may radiate to the carotid arteries. A murmur of mitral valve prolapse may radiate into the left axilla. 
     Today, the physicians must identify the sound radiation by manual auscultation using stethoscopes. Identifying the sound radiations is time consuming, leaves no medical record and depends essentially on the abilities and skills of the physician. 
     Accordingly, there is a need for a technique that would allow a better analysis of the sounds of the body fluid flows. 
     SUMMARY OF THE INVENTION 
     To solve this problem, the invention relates to a method for analysing the sounds of body fluid flows comprising simultaneously acquiring sounds from various locations of a body and determining characteristics of the fluid flows wherein determining characteristics comprises identifying the points of maximum sound intensity of the acquired sounds for each acquisition instant determining the source locations of the acquired sounds, and determining the sound radiation patterns of the acquired sounds. 
     The invention also relates to a device for analysing the sound of body fluid flows comprising an input unit for receiving data corresponding to sounds simultaneously acquired from various locations of a body and an analysing unit for determining fluid flows characteristics wherein said analysing unit comprises means for identifying the points of maximum sound intensity for each acquisition instant, means for determining the source locations of the acquired sounds, and means for determining the sounds radiation patterns of the acquired sounds. 
     The invention also relates to a computer program performing said method and to a system including said device. 
     The invention provides a non invasive solution to analyse characteristics of the body fluid flows in more detail than the existing solutions and especially the sound radiation pattern. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Those and other features and advantages of the invention will become apparent upon reading the following description given only by the way of non limiting example, and offered with reference to the annexed figures in which: 
         FIG. 1  represents a general flow chart of the process of the invention; and 
         FIG. 2  represents a schematic of the system of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The embodiment of the example relates to the acquisition of acoustic heart signals from the entire chest region of a human body, that is to say the analysis of the chest sounds. 
     The method of the invention will now described with reference to  FIG. 1 . 
     The method starts by a simultaneous acquisition  2  of the sounds of body flows by an adapted array of sensors set on specific monitored areas of the body. For each acquisition instant, the sound level for each sensor is recorded. 
     The acquisition is followed by a processing step  4  during which the acquired signals are transformed in order to provide digital signals corresponding to the acquired sounds. In the described example, the output of the processing step is a table referencing the characteristics of the acquired sound for each sensor and for each acquisition instant. 
     Acquisition and processing of acoustic signals for body fluid flows is a well documented technique and will not be described in details. 
     The method then comprises identifying  6  the locations of the maximum sound intensity for each acquisition instant. Accordingly, through the array of sensors, a mapping of the locations of the points of maximal intensity (PMIs) is obtained for each acquisition instant. 
     Advantageously, the method comprises a calibration  8  during which radiation flows cycles and body regions are defined. 
     More precisely, in certain cases, such as for blood flows, body fluid flows present cyclic patterns. This is detected during the calibration by analysing several acquisition instants and identifying said cycles. 
     Similarly, body regions can be defined by the analysis of several acquisition instants by considering the repetitions of the PMIs. In the described example of heart sounds monitoring, four primary regions of acquisition are defined, namely the aortic area, the pulmonic area, the mitral area and the tricuspid area. 
     The method then comprises determining  10  the locations of the sound sources. This sources locations determination is performed by processing several acquisition instants and the location of the maximum of several PMIs is determined as a source location. 
     Advantageously, a source location is determined for each body region. 
     From a practical point of view, in the embodiment described, the calibration and the determination of the source locations are performed simultaneously by use of a loop classification algorithm applied to the PMIs and converging over several acquisition instants. 
     The process then comprises creating  12  an instantaneous sound record with the source locations and the points of maximal intensity. 
     In the embodiment described, this record is formed as a digital image, also called snapshot or frame, graphically representing the source locations of the sounds and the points of maximal intensity. Advantageously other sound characteristics such as frequency, amplitude, duration or the like are also part of this image. 
     The method then comprises determining  14  the radiation pattern for the acquired sounds. In the embodiment described, this is performed by applying a tracking algorithm between consecutive images. Each image containing a distribution of the intensity of sounds, the processor computes how and where the sounds of each source radiate using image tracking algorithms applied to the PMIs associated with that source. 
     Advantageously, the heuristic that the acoustic signals usually radiate in particular patterns is used to refine and guide the tracking system to determine the radiation pattern of the acquired sounds. Reference radiation patterns are used to improve the determination. 
     At that stage, the process of the invention is able to provide both an instantaneous view of the source locations and points of maximum sound intensity as well as radiation patterns tracked over several consecutive images. In the embodiment described those elements are graphically provided to a physician through a display screen. 
     In the embodiment described, the method of the invention also comprises comparing  16  the acquired sounds and determined radiation patterns to references in an attempt to match the acquired sounds and radiation patterns to existing conditions. For example, the output of the comparison system is a correlation percentage identifying the match between the characteristics of the acquired sounds and the references. 
     The comparison allows a categorization of the etiology of the radiation by comparing its location, timing, duration and other characteristics to existing references. 
     This comparison provides a physician with a helpful insight on the diagnosis and assists the physician or the operator in the decision process. Furthermore, the information obtained does not depend upon the skills or abilities of the operator or of the physician and can be recorded for later use. 
     Accordingly, the invention describes a non invasive method for analysing the radiation patterns of body fluid flows and providing help for the diagnosis of medical conditions. 
     With reference to  FIG. 2 , a system according to an embodiment of the invention is now described. 
     The system first comprises a sensor assembly  18  comprising an array of sound sensors which are, in the example, set on an inflatable wearable vest. The inflatable vest also comprises pressure means which are not represented. Those pressure means are used to apply, through the inflatable vest, a similar pressure to each sensor and to press the sensors towards the chest of the human body. 
     For example, the sensors are microphones or piezo-electric sensors. The distribution of the sensors is arranged so that the entire chest region is optimally covered. 
     The sensor assembly  18  performs the simultaneous acquisition  2  of sounds from the body fluid flows as described previously with reference to  FIG. 1 . The sensor assembly  18  is connected to an analysing apparatus  20  which, in the example, is a dedicated device. In another embodiment, this analysing apparatus can be implemented as a mix of software and hardware in another electronic apparatus, such as for example a computer. 
     The analysing apparatus  20  first comprises an input stage  22  with appropriate amplifiers, band-pass filters, and analog to digital converters. Of course, the input stage  22  is adapted to the actual sensors used in the sensor assembly  18 . The input stage  22  performs the processing step  4  as described with reference to  FIG. 1 . 
     The digital signals corresponding to the acquired sounds are then analysed by a processor  24 . 
     The processor  24  first comprises a unit  26  for determining the points of maximum sound intensity or PMIs, as described with reference to step  6  of  FIG. 1 . The processor  24  also comprises a unit  28  for determining the locations of the sources of the acquired sounds. As indicated with reference to  FIG. 1 , in the embodiment described, the calibration  8  is performed through a converging determination  10  of the source locations. Accordingly, unit  28  performs both steps  8  and  10  as described with reference to  FIG. 1 . 
     The output of units  28  and  26  are provided to an image determination unit  30 . As described with reference to step  12 , this image determination unit  30  provides digital images featuring the source locations of the sounds and the points of maximum sound intensity to a radiation pattern determination unit  32 . The radiation pattern determination unit  32  performs the determination step  14  by tracking the points of maximum sound intensity for each source location over several frames. 
     Advantageously, the processor  24  also comprises a pattern comparing unit  34  for performing the comparison step  16  as described with reference to  FIG. 1 . 
     Finally, in the described example, the processor  24  also comprises a display interface  36  for controlling a display screen  40  and displaying the frames, the radiation patterns and the results of the comparing unit to a physician or an operator. 
     Generally speaking the processor  24  is also connected to a memory unit  42  for storing the acquired sounds, the image data, the radiation patterns and any other final or intermediate result. 
     Of course many other embodiments of this system can be realized and the sensors, input stage, processing units, memory and display can be spread over several apparatus or combined. 
     In one embodiment, the sensors are digital wireless sensors connected to a wireless computer running a software program and using the computer screen and memory unit. 
     In such an embodiment, the method described above is performed by a computer program comprising instructions which are executed by a processor of a computer. This program is formed on a computer software medium. 
     In another embodiment, the sensors transmit their data to the processor through a telecommunication network such as the Internet to allow remote monitoring. 
     Of course, the invention can be used for other bodies than the human body and other fluid flows than the blood flows. 
     The invention has been described with reference to the preferred embodiments. Modifications and alterations may occur to others upon reading and understanding the preceding detailed description. It is intended that the invention be constructed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.