Lung function analysis method and apparatus

Abstract

A method for generating data indicative of lung function of a subject. The method comprises receiving first data which has been obtained from the subject, and inputting said first data to a model of lung function to generate said data indicative of lung function. The model of lung function comprises a first model component modelling transfer of gaseous oxygen from a gaseous space within the lung to biological material within the lung based upon quantitative data indicative of oxygen content in the inhaled gases and oxygen content in the biological material and a second model component modelling the transfer of oxygen from the lungs by oxygenation of venous blood to create oxygenated blood based upon quantitative data indicative of oxygen content in the venous blood.

1 - 38 . (canceled) 
     
     
         39 . A computer-implemented method for assessing a subject's lung, the method comprising:
 receiving, at a processor, first data which has been obtained from the subject by performing Oxygen-Enhanced Magnetic Resonance Imaging (OE-MRI);   determining, from the first data, a first time-varying input of a partial pressure of oxygen measured in tissue water;   receiving a second time varying input of a partial pressure of oxygen content in inhaled gases;   receiving a third time varying input of oxygen content in venous blood;   generating, by the processor, an output by fitting a model of lung function to said first time varying input, said second time varying input, and said third time varying input;   wherein the model of lung function comprises a first model component and a second model component, the first model component having a first input corresponding to said first time varying input of a partial pressure of oxygen measured in tissue water and a second input corresponding to said second time varying input of oxygen content in inhaled gases and modelling a transfer of gaseous oxygen from a gaseous space within the lung to a biological material within the lung, the second model component having an input corresponding to said third time varying input of oxygen content in venous blood and modelling a transfer of oxygen from the lungs by an oxygenation of the venous blood to create oxygenated blood; and   determining a measure of ventilation and perfusion within the subject's lung based upon said generated output.   
     
     
         40 . A method according to  claim 39 , wherein the second model component comprises a first parameter representing a volume of blood flow. 
     
     
         41 . A method according to  claim 40 , wherein the generated output includes at least one value for said first parameter representing a volume of blood flow. 
     
     
         42 . A method according to  claim 40 , wherein the first model component comprises a second parameter representing a volume of inhaled gases in at least part of the gaseous space. 
     
     
         43 . A method according to  claim 42 , wherein the generated output includes at least one value for said second parameter representing a volume of inhaled gases in at least part of the gaseous space. 
     
     
         44 . A method according to  claim 42 , further comprising generating, by the processor, data based upon said first parameter and second parameter. 
     
     
         45 . A method according to  claim 44 , wherein generating data based upon said first parameter and said second parameter comprises performing, by the processor, an arithmetic operation on a value of said first parameter and a value of said second parameter. 
     
     
         46 . A method according to  claim 39 , wherein said model of lung function models lung function in a part of a lung comprising a first portion comprising said gaseous space and a second portion comprising said biological material. 
     
     
         47 . A method according to  claim 46 , wherein the first model component comprises a second parameter representing a volume of inhaled gases in at least part of the gaseous space, and said first parameter represents a volume of blood flow thorough said second portion of said part of the lung. 
     
     
         48 . A method according to  claim 46 , wherein the first model component comprises a second parameter representing a volume of inhaled gases in at least part of the gaseous space, and said second parameter represents the volume of inhaled gasses in said first portion of said part of the lung. 
     
     
         49 . A method according to  claim 39 , wherein the third time varying input of oxygen content in the venous blood comprises a plurality of values each relating to oxygen content at a respective time. 
     
     
         50 . A method according to  claim 39 , wherein the method further comprises receiving, at the processor, quantitative data indicative of oxygen content in the venous blood having been obtained from the subject. 
     
     
         51 . A method according to  claim 39 , wherein the model includes a parameter representing a solubility of oxygen in blood. 
     
     
         52 . A method according to  claim 39 , wherein the first model component comprises a first part representing an amount of inhaled gases. 
     
     
         53 . A method according to  claim 52 , wherein the first model component further comprises a second part representing an amount of oxygen diffused into the biological material from the gaseous space. 
     
     
         54 . A method according to  claim 39 , wherein the second model component comprises a first part representing the amount of oxygen diffused into the biological material from the gaseous space. 
     
     
         55 . A method according to  claim 54 , wherein the second model component further comprises a second part representing the transfer of oxygen from the lungs by oxygenation of venous blood. 
     
     
         56 . A method according to  claim 39 , wherein the model is based upon an assumption that concentrations of oxygen in the gaseous space within the lung is substantially equal to a concentration of oxygen in the biological material. 
     
     
         57 . A method according to  claim 39 , wherein the model approximates saturation of oxygen in the blood using a linear function. 
     
     
         58 . A method according to  claim 46 , wherein said model comprises a parameter indicating a proportion of said part of the lung made up of one of said first and second portions. 
     
     
         59 . A method according to  claim 58 , further comprising receiving, at the processor, at least one value for the parameter as an input. 
     
     
         60 . A method according to  claim 59 , wherein the at least one value for the parameter has been obtained from the subject. 
     
     
         61 . A method  claim 58 , wherein said first and second components are combined together in the model according to said proportion. 
     
     
         62 . A method according to  claim 46  wherein the model has the form: 
       
         
           
             
               
                 
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         wherein PW O     2    is an input parameter representing the partial pressure of oxygen in the biological material in said part of the lung; FI O     2    is an input parameter representing the concentration of oxygen inhaled by the subject; C v   O     2    is an input parameter representing the concentration of oxygen present in the venous system of the subject; α′ O     2    is an input parameter which represents the solubility of oxygen in the biological material; β O     2    is an input parameter which represents the solubility coefficient of oxygen in the blood; Co is a scalar value; ν W  is a parameter representing the proportion of biological material in said part of the lung, 
         {dot over (V)}A is an output parameter for the model which represents the volume of inhaled gases within said gaseous space in said part of the lung; and {dot over (Q)} is an output parameter for the model which represents the volume of blood which passes through said part of the lung. 
       
     
     
         63 . A method according to  claim 39 , wherein said first time varying input of a partial pressure of oxygen measured in tissue water is magnetic resonance data. 
     
     
         64 . A method according to  claim 39 , wherein said generating the output comprises application of the Levenberg Marquardt non-linear least squares fitting algorithm to the model so as to fit said model to said first data. 
     
     
         65 . A computer-implemented method for assessing a subject's lung, the method comprising:
 receiving, by a processor, first data obtained from the subject;   determining, from the first data, a first time varying input of a partial pressure of oxygen measured in tissue water;   receiving a second time varying input of a partial pressure of oxygen content in inhaled gases;   receiving a third time varying input of oxygen content in venous blood;   generating, by the processor, an output by fitting a model of lung function to said first time-varying input, said second time-varying input, and said third time varying input, wherein the model of lung function comprises a first model component and a second model component, the first model component having a first input corresponding to said first time varying input of a partial pressure of oxygen measured in tissue water and a second input corresponding to said second time varying input of oxygen content in inhaled gases and modelling a transfer of gaseous oxygen from a gaseous space within the lung to a biological material within the lung, the second model component having an input corresponding to said third time varying input of oxygen content in venous blood and modelling a transfer of oxygen from the lungs by an oxygenation of the venous blood to create oxygenated blood;   determining a first measure of ventilation and perfusion within the subject's lungs while the subject inhales gases comprising a first concentration of oxygen based upon said generated output;   obtaining, by the processor, a second measure of ventilation within the subject's lung and perfusion within the subject's lung while the subject inhales gases comprising a second concentration of oxygen;   generating, by the processor, second data based upon the first measure and the second measure; and   determining, by the processor, a quantitative measure of ventilation within the subject's lung and perfusion within the subject's lung based upon the second data.   
     
     
         66 . A method according to  claim 65  wherein the first concentration of oxygen is approximately 21% and/or the second concentration of oxygen is approximately 100%. 
     
     
         67 . A method according to  claim 65 , wherein obtaining the first data includes obtaining the first data by performing-magnetic resonance imaging. 
     
     
         68 . A method according to  claim 65 , wherein determining the quantitative measure of ventilation within the subject's lung and perfusion within the subject's lung comprises processing, by the processor, the second data using a mathematical model. 
     
     
         69 . A method according to  claim 68  wherein the processing comprises determining, by the processor, at least one value of a parameter of the mathematical model based upon said second data. 
     
     
         70 . A method according to  claim 68 , wherein the mathematical model comprises a first model component modelling transfer of a gaseous oxygen from a gaseous space within the lung to a biological material within the lung based upon a first quantitative data indicative of oxygen content in inhaled gases and oxygen content in the biological material and a second model component modelling a transfer of oxygen from the lungs by an oxygenation of venous blood to create an oxygenated blood based upon a second quantitative data indicative of oxygen content in the venous blood. 
     
     
         71 . A computer program adapted to implement a method for assessing a subject's lung, the computer program carried by a computer readable medium, the computer program comprising:
 computer readable instructions arranged to cause a computer to
 receive first data obtained from the subject; 
 determine, from the first data, a first time varying input of a partial pressure of oxygen measured in tissue water; 
 receive a second time varying input of a partial pressure of oxygen content in inhaled gases; 
 receive a third time varying input of oxygen content in venous blood; 
 generate an output by fitting a model of lung function to said first time varying input, said second time varying input, and second third time varying input, 
 wherein the model of lung function comprises a first model component and a second model component, the first model component having a first input corresponding to said first time varying input of a partial pressure of oxygen measured in tissue water and a second input corresponding to said second time varying input of oxygen content in inhaled gases and modelling a transfer of a gaseous oxygen from a gaseous space within the lung to a biological material within the lung, the second model component having an input corresponding to third time varying input of oxygen content in venous blood and modelling a transfer of oxygen from the lungs by an oxygenation of the venous blood to create an oxygenated blood; and 
 determining a measure of ventilation and perfusion within the subject's lung based upon said generated output. 
   
     
     
         72 . An apparatus for assessing a subject's lung, the apparatus comprising:
 a memory storing processor readable instructions; and   a processor arranged to read and execute instructions stored in said program memory;   wherein said processor readable instructions comprise instructions arranged to cause the processor to   receive first data obtained from the subject;   determine, from the first data, a first time varying input of a partial pressure of oxygen measured in tissue water;   receive a second time varying input of a partial pressure of oxygen content in inhaled gases;   receive a third time varying input of oxygen content in venous blood;   generate an output by fitting a model of lung function to said first time varying input, said second time varying input, and said third time varying input,   wherein the model of lung function comprises a first model component and a second model component, the first model component having a first input corresponding to said first time varying input of a partial pressure of oxygen measured in tissue water and a second input corresponding to said second time varying input of oxygen content in inhaled gases and modelling a transfer of a gaseous oxygen from a gaseous space within the lung to a biological material within the lung, the second model component having an input corresponding to said third time varying input of oxygen content in venous blood and modelling a transfer of oxygen from the lungs by an oxygenation of the venous blood to create an oxygenated blood; and   determine a measure of ventilation and perfusion within the subject's lung based upon said generated output.