Method and related system for measuring intracranial pressure

Abstract

A method for measuring intracranial pressure in an intracranial area filled with micro-bubbles formed by an injected contrast agent includes: (1) emitting an ultrasound signal having a bandwidth to the intracranial area, (2) receiving an echoed signal from a micro-bubble, (3) performing a spectral analysis on the echoed signal to extract a low-frequency response, which is close to a DC component, (4) calculating a resonant frequency of the micro-bubbles according to the bandwidth and strength of the low-frequency response, the bandwidth of the low-frequency response similar to the bandwidth of the ultrasound signal, (5) calculating a size of the micro-bubble according to the resonant frequency and a property of the contrast agent, and (6) calculating the intracranial pressure.

1 . A method for measuring intracranial pressure in an intracranial area filled with micro-bubbles formed by an injected contrast agent, the method comprising: 
 (a) emitting an ultrasound signal having a bandwidth to the intracranial area;    (b) receiving an echoed signal from a micro-bubble;    (c) performing a spectral analysis on the echoed signal and extracting a low-frequency response, the bandwidth of the low-frequency response similar to the bandwidth of the ultrasound signal;    (d) calculating a resonant frequency of the micro-bubble according to the low-frequency response; and    (e) calculating a size of the micro-bubble and a pressure of the intracranial area according to the resonant frequency and a property of the contrast agent.    
   
   
       2 . The method of  claim 1  wherein step (d) comprises deriving a parameter from the bandwidth and a parameter from the strength of the low-frequency response and using an empirical equation to calculate the resonant frequency of the micro-bubble.  
   
   
       3 . The method of  claim 2  wherein the bandwidth parameter is normalized by dividing the bandwidth of the low-frequency response by a central frequency of the ultrasound signal, and the strength parameter is normalized by dividing the strength of the low-frequency response by a maximum strength of the ultrasound signal.  
   
   
       4 . The method of  claim 1  wherein step (e) comprises calculating the micro-bubble size according to a correlation between sizes of micro-bubbles and the resonant frequency of micro-bubbles, the correlation depending on the property of the contrast agent.  
   
   
       5 . The method of  claim 4  wherein the product of the resonant frequency and a diameter of the micro-bubble is a constant value.  
   
   
       6 . A system for measuring intracranial pressure in an intracranial area filled with micro-bubbles formed by an injected contrast agent, the system comprising: 
 a transmitter module for emitting an ultrasound signal having a bandwidth to the intracranial area;    a receiver module for receiving an echoed signal from a micro-bubble; and    a signal processing module connected to the receiver module, the signal processing module comprising:    a low-frequency capture unit for performing a spectral analysis on the echoed signal and extracting a low-frequency response, the bandwidth of the low-frequency response similar to the bandwidth of the ultrasound signal;    a resonant frequency calculation unit for calculating a resonant frequency of the micro-bubble according to the low-frequency response; and    a pressure calculation unit for calculating a size of the micro-bubble according to the resonant frequency and a property of the contrast agent, and further calculating a pressure of the intracranial area.    
   
   
       7 . The system of  claim 6  wherein the resonant frequency calculation unit derives a parameter from the bandwidth and a parameter from the strength of the low-frequency response and uses an empirical equation to calculate the resonant frequency of the micro-bubble.  
   
   
       8 . The system of  claim 7  wherein the bandwidth parameter is normalized by dividing the bandwidth of the low-frequency response by a central frequency of the ultrasound signal, and the strength parameter is normalized by dividing the strength of the low-frequency response by a maximum strength of the ultrasound signal.  
   
   
       9 . The system of  claim 6  wherein the pressure calculation unit calculates the micro-bubble size according to a correlation between sizes of micro-bubbles and the resonant frequency of micro-bubbles, the correlation depending on the property of the contrast agent.  
   
   
       10 . The system of  claim 9  wherein the product of the resonant frequency and a diameter of the micro-bubble is a constant value.  
   
   
       11 . A method of using an ultrasound contrast agent to measure pressure in a target area filled with micro-bubbles formed by the injected contrast agent, the method comprising: 
 (a) emitting an ultrasound signal having a bandwidth to the target area;    (b) receiving an echoed signal from a micro-bubble;    (c) performing a spectral analysis on the echoed signal and extracting a low-frequency response, the bandwidth of the low-frequency response similar to the bandwidth of the ultrasound signal;    (d) calculating a resonant frequency of the micro-bubble according to the low-frequency response; and    (e) calculating a size of the micro-bubble and a pressure of the target area according to the resonant frequency and a property of the contrast agent.    
   
   
       12 . The method of  claim 11  wherein step (d) comprises deriving a parameter from the bandwidth and a parameter from the strength of the low-frequency response and using an empirical equation to calculate the resonant frequency of the micro-bubble.  
   
   
       13 . The method of  claim 12  wherein the bandwidth parameter is normalized by dividing the bandwidth of the low-frequency response by a central frequency of the ultrasound signal, and the strength parameter is normalized by dividing the strength of the low-frequency response by a maximum strength of the ultrasound signal.  
   
   
       14 . The method of  claim 11  wherein step (e) comprises calculating the micro-bubble size according to a correlation between sizes of micro-bubbles and the resonant frequency of the micro-bubbles, the correlation depending on the property of the contrast agent.  
   
   
       15 . The method of  claim 14  wherein the product of the resonant frequency and a diameter of the micro-bubble is a constant value.  
   
   
       16 . A system of using an ultrasound contrast agent to measure pressure in a target area filled with micro-bubbles formed by the injected contrast agent, the system comprising: 
 a transmitter module for emitting an ultrasound signal having a bandwidth to the target area;    a receiver module for receiving an echoed signal from a micro-bubble; and    a signal processing module connected to the receiver module, the signal processing module comprising:    a low-frequency capture unit for performing a spectral analysis on the echoed signal and extracting a low-frequency response, the bandwidth of the low-frequency response similar to the bandwidth of the ultrasound signal;    a resonant frequency calculation unit for calculating a resonant frequency of the micro-bubble according to the low-frequency response; and    a pressure calculation unit for calculating a size of the micro-bubble according to the resonant frequency and a property of the contrast agent, and further calculating a pressure of the target area.    
   
   
       17 . The system of  claim 16  wherein the resonant frequency calculation unit derives a parameter from the bandwidth and a parameter from the strength of the low-frequency response and uses an empirical equation to calculate the resonant frequency of the micro-bubble.  
   
   
       18 . The system of  claim 1   7  wherein the bandwidth parameter is normalized by dividing the bandwidth of the low-frequency response by a central frequency of the ultrasound signal, and the strength parameter is normalized by dividing the strength of the low-frequency response by a maximum strength of the ultrasound signal.  
   
   
       19 . The system of  claim 16  wherein the pressure calculation unit calculates the micro-bubble size according to a correlation between sizes of micro-bubbles and the resonant frequency of the micro-bubbles, the correlation depending on the property of the contrast agent.  
   
   
       20 . The system of  claim 19  wherein the product of the resonant frequency and a diameter of the micro-bubble is a constant value.