Abstract:
A blood cell analyzer is provided with a first detection unit for electrically detecting blood cells in blood sample; a second detection unit for optically detecting blood cells in blood sample; a volume information obtainer for obtaining volume information of red blood cells based on the electrically detected blood cells; a scattered light intensity information obtainer for obtaining a scattered light intensity of red blood cells based on the optically detected blood cells; a first histogram preparer for preparing a first histogram of the volume information of each of red blood cells; a second histogram preparer for preparing a second histogram of the scattered light intensity information of each of red blood cells; a display unit; and a data processor for preparing a screen for displaying on the display unit, the screen including the first and second histograms.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority from Japanese Patent Application 2006-342228, filed on Dec. 20, 2006, the entire disclosure of which is incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention relates to a blood cell analyzer capable of measuring blood cells in a measurement sample, and outputting information useful for the diagnosis and treatment of blood diseases and the like, to a blood cell analyzing method, and to a computer program product thereof. 
     BACKGROUND 
     Anemia is a blood condition in which there is a reduction in number of red blood cells, and the amount of hemoglobin contained in the red blood cells is also reduced. Anemia is generally screened on the basis of measurement results of items such as the red blood cell count (RBC), amount of hemoglobin (HGB), hematocrit value (HCT), mean cell volume (MCV), mean cell hemoglobin (MCH), mean cell hemoglobin concentration (MCHC) and the like obtained from a blood cell analyzer. However, it is difficult to distinguish the type of anemia by such a screening examination even though the degree of anemia can be determined. Since there are various causes of anemia, a physician can not be sure of the precise treatment to pursue because the type of anemia can not be identified. 
     Iron deficiency anemia and β thalassemia, for example, are caused by blood disease. Both diseases are caused by impeded production of red blood cells, and exhibit low values for MCV and MCH. It is difficult to distinguish between iron deficiency anemia and β thalassemia because low hemoglobin is a characteristic of small cells. Furthermore, it is difficult to differentiate between mild (minor) cases of β thalassemia and iron deficiency anemia. 
     The following facts are known based on this background and experiments were performed to classify types of anemia based on information obtained from blood cell analyzers. 
     (1) U.S. Pat. No. 4,735,504 discloses art which provides information concerning erythrocytic disease and anemic conditions through the determination of individual red cell volume (V) and hemoglobin concentration (HC) by flowing a sample liquid containing blood cells through a flow cell and detecting and analyzing two types of light signals which are emitted from the particles at different angles. 
     (2) Japanese Laid-Open Patent Publication No. 11-326315 discloses art which discriminates between juvenile blood, iron deficiency anemia, and β thalassemia foremost by utilizing a predetermined method on a plurality of data obtained from a blood analyzer. 
     (3) U.S. Pat. No. 6,535,836 discloses art which determines blood anomalies by setting a lower limit value and an upper limit value determined from the particle size distribution of normal blood on a particle size distribution curve for red blood cells. 
     (4) U.S. Pat. No. 6,535,836 discloses art which determines iron metabolism anomalies by combining three parameters obtained from several types of clinical examinations as a method for identifying anemia. The parameters used include the percentage of low hemoglobin red blood cells (HRC %) and the hemoglobin content in reticulocytes (CHr). 
     (5) US Laid-Open Patent Publication No. 2005-0219527 discloses art which discriminates types of anemia by calculating the reticulocyte hemoglobin content (RET-He) and hemoglobin content in mature red blood cells (RBC-He) from the forward scatter light intensity and the side fluorescent light intensity coming from individual blood cells obtained from a blood analyzer. 
     Since several examinations are normally necessary to diagnose anemia, it would be extremely beneficial from the perspective of clinical examinations if suitable treatment could be provided at an early stage and at low cost using only a blood cell analyzer without performing a special examination to provide useful identification information. 
     SUMMARY 
     The scope of the present invention is defined solely by the appended claims, and is not affected to any degree by the statements within this summary. A blood cell analyzer embodying features of the present invention includes: a first detection unit for electrically detecting blood cells in blood sample; a second detection unit for optically detecting blood cells in blood sample; a volume information obtainer for obtaining volume information of red blood cells based on the electrically detected blood cells by the first detection unit; a scattered light intensity information obtainer for obtaining a scattered light intensity of red blood cells based on the optically detected blood cells by the second detection unit; a first histogram preparer for preparing a first histogram of the volume information of each of red blood cells obtained by the volume information obtainer; a second histogram preparer for preparing a second histogram of the scattered light intensity information of each of red blood cells obtained by the scattered light intensity information obtainer; a display unit; and a data processor for preparing a screen for displaying on the display unit, the screen including the first and second histograms prepared by the first and second histogram preparer. 
     A blood cell analyzing method embodying features of the present invention includes steps of: electrically detecting blood cells in blood sample; optically detecting blood cells in blood sample; obtaining volume information of red blood cells based on the electrically detected blood cells; obtaining scattered light intensity information of red blood cells based on the detected optically blood cells; preparing a first histogram using as parameters the volume information of each of red blood cells; preparing a second histogram using as parameters the scattered light intensity information of each of red blood cells; and displaying a screen including the first and second histograms. 
     A computer program product for enabling a computer to execute a method of analyzing blood cells in a biological sample, the computer program product embodying features of the present invention includes: a computer readable medium; and software instructions, on the computer readable medium, for enabling the computer to perform predetermined operations comprising: electrically detecting blood cells in blood sample; optically detecting blood cells in blood sample; obtaining volume information of red blood cells based on the electrically detected blood cells; obtaining scattered light intensity information of red blood cells based on the detected optically blood cells; preparing a first histogram using as parameters the volume information of each of red blood cells; preparing a second histogram using as parameters the scattered light intensity information of each of red blood cells; and displaying a screen including the first and second histograms. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an external view of an embodiment of the blood cell analyzer of the present invention; 
         FIG. 2  is a block diagram of the fluid processing unit; 
         FIG. 3  is a schematic view of an example of an electrical resistance type detection unit; 
         FIG. 4  is a perspective view of an example of an optical type detection unit; 
         FIG. 5  is a block diagram of a measuring device; 
         FIG. 6  shows an example of a distribution map of red blood cells detected by an electrical resistance type detection unit; 
         FIG. 7  shows thresholds displayed in the distribution map of  FIG. 6 ; 
         FIG. 8  shows an example of a distribution map of red blood cells detected by an optical type detection unit; 
         FIG. 9  shows a distribution map of red blood cells detected by an optical type detection unit; 
         FIG. 10  shows an example of the flow of the analysis processing of data detected by the electrical resistance type detection unit; 
         FIG. 11  shows an example of the flow analysis processing of data detected by the optical type detection unit; and 
         FIG. 12  shows a display screen displaying the analysis results. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The embodiment of the blood cell analyzer of the present invention is described hereinafter with reference to the drawings. 
       FIG. 1  is an external view of an example of a blood cell analyzer. This apparatus is configured as a multifunction automatic blood cell analyzer, which has functions to measure a blood sample contained in a sample container (blood collection tube), and output the measurement results to a display or the like. The analyzer classifies and counts mature blood cells such as white blood cells, red blood cells, platelets and the like, as well as immature blood cells. 
     The blood cell analyzer  1  is configured by a measuring device  2  which is provided with a fluid processing unit for diluting blood in a sample with dilution fluid and reacting the blood with reagent, a detection unit for detecting particle signals of the prepared measurement sample, and a signal processing unit for processing the detected particle signals, the blood cell analyzer  1  is also provided with a data processing device  3  which processes and stores the data obtained by the measuring device  2  and outputs the measurement results. Although the blood cell analyzer  1  of the present embodiment is configured by the measuring device  2  and data processing device  3  which are separate devices, both may be integrated as a single apparatus. The measuring device  2  is provided with a display and operating unit  7 . The data processing device  3  is provided with a data processing unit  301 , display unit  302 , and input unit  303 . 
     Each part of the blood cell analyzer  1  is described in detail below. 
       FIG. 2  is a block diagram of a fluid processing unit  81  (refer to  FIG. 5 ). 
     The blood, that is, the sample, within the test tube is aspirated by set dosage pump (not shown in the drawing) and introduced to a sampling valve  91 . Measurement samples are prepared by collecting fixed quantities of sample in the sampling valve  91 , and mixing the collected fixed quantity samples  92   a  through  92   f  with reagents which are supplied fixed quantities of dilution fluid and reagents by dosage pumps  93   a  through  93   f,  in reaction chambers  95   a  through  95   f.    
     The fixed quantity sample  92   f  collected in the sampling valve  91  is supplied to the reaction chamber  95   f  together with a fixed quantity of dilution fluid supplied by a dosage pump  93   f.  A fixed quantity of stain is also supplied to the reaction chamber  95   f  by a dosage pump  94   f.  Measurement samples are prepared for four types of white blood cells (4DIFF) by combining the sample  92   f,  dilution fluid, and stain in the reaction chamber  95   f.    
     The fixed quantity sample  92   e  collected in the sampling valve  91  is supplied to the reaction chamber  95   e  together with a fixed quantity of dilute hemolytic agent supplied by the dosage pump  93   e.  A fixed quantity of stain is also supplied to the reaction chamber  95   e  by a dosage pump  94   e.  A measurement sample for nucleated red blood cells (NRBC) is prepared by combining the sample  92   e,  dilute hemolytic agent, and stain in the reaction chamber  95   e.    
     The fixed quantity sample  92   d  collected in the sampling valve  91  is supplied to the reaction chamber  95   d  together with a fixed quantity of dilution fluid supplied by the dosage pump  93   d.  A fixed quantity of stain is also supplied to the reaction chamber  95   d  by a dosage pump  94   d.  A measurement sample for reticulocytes (RET) is prepared by combining the sample  92   d,  dilution fluid, and stain in the reaction chamber  95   d.  The reagent kit “RET search II” which is manufactured by Sysmex Corporation is suitable for use as the dilution fluid and stain. The stain in this reagent kit contains ethylene glycol and polymethene dyestuff, and is capable of staining erythrocytes, reticulocytes, and platelets. 
     The fixed quantity sample  92   c  collected in the sampling valve  91  is supplied to reaction chamber  95   c  together with a fixed quantity of dilute hemolytic agent supplied by the dosage pump  93   c.  A measurement sample for white blood cells and basophils (WBC/BASO) is prepared by combining the sample  92   c  and dilute hemolytic agent in the reaction chamber  95   c.    
     The fixed quantity sample  92   a  collected in the sampling valve  91  is supplied to the reaction chamber  95   a  together with a fixed quantity of dilution fluid supplied by the dosage pump  93   a.  A measurement sample for red blood cells and platelets (RBC/PLT) (hereinafter referred to as “RBC sample”) is prepared by combining the sample  92   a  and dilution fluid in the reaction chamber  95   a.    
     The hemoglobin (HGB) measurement sample, which is a mixture of the fixed quantity sample  92   b  collected by the sampling valve  91  and the fixed quantity dilute hemolytic agent supplied by the dosage pump  92   b,  is supplied to a hemoglobin detection unit  42 . The hemoglobin detection unit  42  measures the absorption light of the hemoglobin (HGB) measurement sample. 
     The NRBC sample in the reaction chamber  95   e,  the WBC/BASO sample in the reaction chamber  95   c,  the 4DIFF sample in the reaction chamber  95   f,  and the RET sample in the reaction chamber  95   d  are sequentially introduced to an optical type detection unit  43  by a dosage syringe  97 . The block  94   h  is a means for supplying sheath liquid to the detection unit  43 . 
     The RBC sample in the reaction chamber  95   a,  however, is introduced to an electrical resistance type detection unit  41  by a dosage syringe  96 . The block  94   g  is a means for supplying sheath liquid to the detection unit  41 . 
     Thus, the detection unit  4  is provided with an electrical resistance type detection unit  41  for measuring red blood cells, s hemoglobin detection unit  42  for detection the amount of hemoglobin in blood cells, and an optical type detection unit  43  for detecting white blood cells and reticulocytes. 
     The detection units  41  and  43  are described in detail below. 
       FIG. 3  shows an example of the electrical resistance type detection unit  41  using a sheath flow. The RBC sample containing red blood cells is extracted from a nozzle  101  at a constant speed by a dosage syringe  96  and encapsulated by a surrounding front sheath liquid  102  before passing through an orifice  103 . After passing through the orifice, the measurement sample is collected together with a back sheath  104  in a recovery tube  105 . Electrodes (not shown in the drawing) are disposed so as to have the orifice  103  interposed therebetween, and the peak values of particle signals, which are proportional to the volume of the particle, are detected for each particle flowing through the orifice  103 . 
       FIG. 4  shows the detection unit  43  for optically measuring particles. The measurement samples prepared in the reaction chambers  95   e,    95   c,    95   f,  and  95   d  are extracted from nozzles at constant speed by a dosage syringe  47  and encapsulated by a surrounding sheath liquid before flowing through the orifice of the sheath flow cell  403 . A laser beam emitted from a laser diode  401  irradiates the orifice area of the sheath flow cell  403  through a collimator lens  402 . The forward scattered light from blood cells passing through the region of the orifice irradiated by the laser beam enter a photodiode  406  through a collective lens  404  which is provided with a beam stopper, and a pin hole plate  405 . Among the lateral light from the blood cells passing through the region of the orifice irradiated by the leaser beam, the side scattered light enters the a photomultiplier tube (hereinafter referred to as “photomultiplier”)  412  through a collective lens  407  and a dichroic mirror  408 , and the side fluorescent light enters an optical filter  409  via the dichroic mirror  408 , then enters a photomultiplier  411  through a pinhole plate  410 . 
     The forward scattered light signal from the photodiode  406  is subjected to various types of signal processing by a detection circuit  51 , and thereafter send to a digital signal processing unit  6 . The side scattered light signal from the photomultiplier  412  is subjected to various types of signal processing by a detection circuit  53 , and thereafter sent to the digital signal processing unit  6 . The side fluorescent light signal from the photomultiplier  411  is subjected to various types of signal processing by a detection circuit  52 , and thereafter sent to the digital signal processing unit  6 . 
     The signal processing and data processing are described in detail below. 
       FIG. 5  shows an example of a block diagram of the measuring device  2  of the analyzer. 
     The particle signals detected by the detection unit  4  are subjected to signal processing by a signal processing unit  5  which performs analog signal processing, and subjected to data processing and analysis by a digital signal processing unit  6  which performs digital signal processing, then the resulting signals are sent to a data processing device  3  which displays and stores the results. A mechanism and fluid unit  8  is provided with a fluid processing unit  81 . The operation and display unit  7 , which is provided in the measuring device  2 , is provided with a touch panel type liquid crystal panel  71 . 
     The forward scattered light signals, side scattered light signals, and side fluorescent light signals from the optical type detection unit  43  are detected and amplified by the respective detection circuits  51 ,  53 , and  52 . The signals from the electrical resistance type detection unit  41  are input to a detection circuit  54  and subjected to red blood cell signal processing and platelet signal processing, and respectively output. The signals from the hemoglobin detection unit  42  are detected and amplified by a detection circuit  55 . 
     The signals from the detection circuits  51  through  54  are respectively subjected to waveform processing in waveform processing circuits  56  and  57  to eliminate noise and facilitate signal processing. The signals from the detection circuit  55  pass through a conversion circuit  58 , and hemoglobin concentration data are determined by a counting circuit  63 . After waveform processing, each particle signal is sequentially subjected to A/D conversion by A/D conversion circuits  61  and  62 , and the A/D converted data are input to the distribution data generating units  64  and  65  and stored therein, and the final particle distribution data are generated. 
     When the distribution data are generated in the distribution generating units  64  and  65 , a control processor  72  obtains the distribution data through an interface  66  and a bus  68 , and the data are then sent to an analysis processor  74  through an interface  73 . The analysis processor  74  analyzes clustering and the like in the distribution data. The analysis results are sent to an external data processing device  3  through an interface  75 , and the data processing device  3  executes processes for screen display and storage of the data. 
     Details of the blood cell analysis are described below. The methods for performing particle analysis of the target red blood cells and providing information useful for the diagnosis and treatment of anemia are described below. Primary distribution data (histogram data) generated using as parameters the volume information obtained by measuring the RBC sample in the sheath flow electrical resistance type detection unit, and secondary distribution data (scattergram data) generating using as parameters the forward scattered light intensity and side fluorescent light intensity obtained by measuring the RET sample in the optical type detection unit are used. New information is obtained by analyzing the distribution data in the analysis processor. 
       FIG. 6  is a red blood cell histogram (RBC histogram) measured from the RBC sample, and  FIG. 7  is a histogram displaying demarcation lines M 1  and M 2  in the histogram of  FIG. 6 . The horizontal axis of the histograms of  FIGS. 6 and 7  (RBC histogram) is volume information (fL), and the vertical axis is the relative number (%).  FIG. 10  is a flow chart of the analysis process. 
     The analysis processor  74  generates an RBC histogram shown in  FIG. 6  when the distribution data obtained from the RBC sample is received from the distribution data generating unit  65  (step S 11 ). The analysis processor  74  reads and displays the demarcation line (threshold value) M 1  set for the small region and the demarcation line (threshold value) M 2  set for the large region of the RBC histogram shown in  FIG. 7  from memory (step S 12 ). The demarcation line M 1  is a value equivalent to 70 fL, and the demarcation line M 2  is a value equivalent to 110 fL. Next, the analysis processor  74  calculates the percentage (MicroR) of red blood cells in the region below the demarcation line M 1  relative to the total number of red blood cells in the RBC histogram, and calculates the percentage (MacroR) of red blood cells in the region above the demarcation line M 2  relative to the total number of red blood cells (step S 13 ). The analysis processor  74  then displays a display screen that includes the RBC histogram which uses the volume of red blood cells as a parameter, and the MicroR and MacroR on the display unit of the data processing unit (step S 14 ). 
       FIG. 8  shows a scattergram obtained by measuring the RET sample (the vertical axis denotes forward scattered light intensity, and the horizontal axis denotes side fluorescent light intensity), and  FIG. 9  shows a histogram obtained from the mature red blood cells Rb in the scattergram of  FIG. 8  (the vertical axis denotes relative number, and the horizontal axis denotes forward scattered light intensity).  FIG. 11  is a flow chart of the analysis process. In the scattergram of  FIG. 8 , Rb refers to mature the red blood cell distribution, Re refers to the reticulocyte distribution, and Pt refers to platelet distribution. 
     The analysis processor  74  generates the scattergram shown in  FIG. 8  when distribution data obtained from the RET sample are received from the distribution generating unit  64  (step S 21 ). The analysis processor  74  executes clustering analysis of the distribution data received from the distribution data generating unit  64  based on the scattered light intensity and fluorescent light intensity, and identifies the particles related to mature red blood cells Rb (step S 22 ). The analysis processor  74  then generates a histogram using as parameters the forward scattered light of each particle identified as a mature red blood cell Rb (referred to as “RBC-Y histogram below”) (step S 23 ). 
     Next, the analysis processor  74  reads from memory and displays the demarcation line (threshold value) L 1  set for the small region, and the demarcation line (threshold value) L 2  set for the large region of the RBC-Y histogram shown in  FIG. 9 . The scattered light intensity of the red blood cells is a parameter which reflects the amount of hemoglobin contained in the red blood cells, the demarcation line L 1  is a scattered light intensity which is equivalent to 27 pg of hemoglobin, and the demarcation line L 2  is a scattered light intensity which is equivalent to 33 pg of hemoglobin. The analysis processor  74  calculates the percentage of red blood cells (LScRBC) in the region below the demarcation line L 1  relative to the total number of red blood cells, and calculates the percentage of red blood cells (HScRBC) in the region above the demarcation line L 2  in the RBC-Y histogram (step S 25 ). The analysis processor  74  displays a display screen which includes the RBC-Y histogram generated using the forward scattered light intensity of red blood cells as a parameter, the LScRBC, and the HScRBC on the display unit of the data processing unit  2 . Furthermore, the analysis processor  74  displays the RBC histogram side by side with the RBC-Y histogram on the display screen. 
       FIG. 12  shows an example of a display screen  200 . 
     An attribute display region  201  for displaying sample or patient attributes is provided at the top of the screen  200 , and specifically, the sample number, patient name, sex, date of birth, ward, attending physician, date of measurement, time of measurement, comment and the like are displayed therein. A measurement result display region for displaying the results of a measurement is provided at the bottom of the attribute display region  201 . Reference number  202  refers to tabs for switching the display content of the measurement result display region; there are a plurality of tabs which correspond to various items such as main menu, graph screen and the like.  FIG. 12  shows the condition when the research (RBC related) tab is selected. A text display region for displaying numerical values and flags is provided in the left half of the measurement result display region, and a distribution map display region for displaying distribution maps is provided on the right half. Provided in the measurement result display region are a display region  203  for displaying the results of measurement items such as RBC, HGB, HCT, HFR and the like, a display region  204  for displaying flagging results related to RBC or RET, and a display region  205  for displaying research items such as RBC-O, RET-He, RBC-He, NRBC % and the like. A display region  76  is also provided for displaying the values of the four items of LScRBC, HScRBC, MicroR, and MacroR among the research items in the display region  205 . 
     In this example, five distribution maps are displayed in the distribution map display region. The five distribution maps include an RET sample scattergram  77  in which the vertical axis denotes forward scattered light intensity and the horizontal axis denotes the side fluorescent light intensity, a scattergram  206  in which the scale of the horizontal axis of the scattergram  77  is changed in the display, an NRB sample scattergram  207  in which the vertical axis denotes the forward scattered light intensity and the horizontal axis denotes the side fluorescent light intensity, an RBC histogram  78 , and an RBC-Y histogram  79 . The RBC histogram,  78  and the RBC-Y histogram  79  are displayed side by side. Thus, Differences in the distributions of the histograms can be readily understood since the RBC histogram  78  and the RBC-Y histogram  79  are displayed side by side. 
     Furthermore, the demarcation lines M 1  and M 2  may be displayed in the RBC histogram  78 , and the demarcation lines L 1  and L 2  may be respectively displayed in the RBC-Y histogram  79 . Thus, differences in the distribution patterns can be readily understood by displaying the demarcation lines in the distribution maps. In the present embodiment, the demarcation lines L 1  and L 2  are displayed in the RBC-Y histogram. 
     The scattered light intensity which is used as a parameter for the RBC-Y histogram is information that reflects the size of the red blood cell, and also reflects the hemoglobin concentration in the red blood cell since it is measured optically. However, the RBC histogram uses the red blood cell volume as a parameter. β thalassemia characteristically has a low value for MicroR and a high value for LScRBC. Therefore, a physician can readily understand that a patient has β thalassemia by displaying the RBC histogram and RBC-Y histogram side by side. 
     Furthermore, iron deficiency anemia and β thalassemia can be differentiated using the four indices. For example, three groups which include normal, iron deficiency anemia, and β thalassemia can be differentiated by performing multi group differentiation analysis of the four indices obtained from the measurement of the blood sample. That is, if one has, beforehand, the four indices information obtained by measuring a plurality of samples of normal blood, and blood of patients with iron deficiency anemia, and blood of patients with β thalassemia, then it is possible to determine to which group a blood sample belongs based on the indices obtained by measuring the blood sample. Easily understandable and useful information can be obtained by this differentiation analysis. 
     Although the functions and structure related to analysis and output performed by the blood cell analyzer of the present embodiment has been described in terms of being provided to the blood cell analyzer beforehand, the same functions may also be realized by a computer program, such that the functions of the present embodiment can be realized in a conventional blood cell analyzer by installing the computer program in the conventional blood cell analyzer. 
     Although a scattered light intensity histogram for mature red blood cells Rb generated from a scattergram obtained by measuring a RET sample is used as the RBC-Y histogram in the present embodiment, it is to be noted that a scattered light intensity histogram of reticulocytes Re and mature red blood cells Rb in the scattergram may also be used for the purpose. 
     Since the blood cell analyzer of the present invention calculates and analyzes a plurality of distribution data for target blood cells obtained by different particle detection principles as described above, information useful for the diagnosis and treatment of diseases can be obtained at low cost by comparing the distribution maps. Moreover, easily understandable information can be effectively obtained by outputting the distribution maps in the same format, and outputting the distribution maps together with the indices related to the distributions.