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    PATENT APPLICATION NO 1200357-0 Brannstrom, Jansson, Marsal & Thuring1 (6) 1. Summary of the invention The invention is a non-invasive, standardized and objective method of characterizing the blood flow in blood vessels in the cardiovascular system. The invention is a specific signal processing algorithm applied to standardized Doppler ultrasound signals of blood flow rates. The invention uses the Fast Fourier Transform on a time window comprising at least one complete cardiac cycle (but at least two or more complete cardiac cycles) and extracts various spectral properties to characterize the Doppler signals. By using delta spectral content, the invention identifies the frequency band that contains a desired amount of spectral energy in the signal and the frequency band where this energy has fallen to a certain level. The invention offers a measure of blood flocculation which is more robust and easier to obtain than usual blood flow parameters.
    公开号:SE1200357A1
    申请号:SE1200357
    申请日:2012-06-13
    公开日:2013-12-14
    发明作者:Jonas Braennstroem；Tomas Jansson；Karel Marsal；Ann Thuring
    申请人:
    IPC主号:
    专利说明:

    PATENT APPLICATION NO 1200357-0 Brannstrom, Jansson, Marsal & Thuring1 (6) 1. Summary of the invention The invention is a non-invasive, standardized and objective method of characterizing the blood flow in blood vessels in the cardiovascular system. The invention is a specific signal processing algorithm applied to standardized Doppler ultrasound signals of blood flow rates. The invention uses the Fast Fourier Transform on a time window comprising at least one complete cardiac cycle (but at least two or more complete cardiac cycles) and extracts various spectral properties to characterize the Doppler signals. By using delta spectral content, the invention identifies the frequency band that contains a desired amount of spectral energy in the signal and the frequency band where this energy has fallen to a certain level. The invention offers a measure of blood flocculation which is more robust and easier to obtain than usual blood flow parameters.
    PATENT APPLICATION NO 1200357-0 Brannstrom, Jansson, Marsal & Thuring2 (6) 2. Description 2.1. General description The blood flow is characterized by its pulsation which is due to the pumping movement of the heart. This pulsation varies the blood flow rate, which can be detected by Doppler ultrasound warnings. The current methods for characterizing the blood flow are based on demanding reports, give imprecise results or results with poor resolution. The invention solves all these responsibilities and offers a simple and reliable method of feeding blood flow rate.
    The Doppler principle refers to the relationship between the speed of a reflector in motion and the change in frequency of the transmitted waveform - e.g. a sound wave. When the reflector moves towards the sound source, the reflected sound will be received at a higher frequency than the one that is sent out. Conversely, as the reflector moves away from the cold, the frequency of the received sound will be lower than that of the emitter. A similar effect also occurs when the kdllan moves in relation to a stationary reflector. The change in frequency is called the father Doppler shift and is described by the Doppler equation. In bloodstream feeds, the ultrasound is generated by a piezoelectric crystal at a given frequency, reflected by the red cells in motion in the vessel, and received at another frequency. The blood flow rate can be calculated when the angle of insonation is known. The ultrasonic frequency is usually 1 to 10 MHz; The Doppler shift caused by the blood flow is then within an audible range. The detected Doppler shift is a spectrum of frequencies rather than a single frequency, as it originates in red cells that move at different speeds in the lumen of the man. The appearance of the Doppler spectrum is related to the blood flow profile of the cross section of the vessel (Evans & McDicken, 2000).
    From the Doppler spectrum, both the maximum velocity (i.e. the spectrum contour) and the average velocity (i.e. the weighted average Doppler shift frequency) can be estimated. This spectrum is determined by using fixed Fourier transform (FFT) over a short period of time (10ms) and subsequent spectra allow the maximum or average velocity to be dropped during a speed stroke. The waveform recorded in this way has the maximum speed from which arteries can be further characterized by different indices. A number of page indices have been developed to characterize the vagrants mathematically. Most waveform indices express the degree of pulsatility in the velocity waveform. Some of them use only two points on the curve - e.g. resistance index (SI) according to Pourcelot (1974); some include the average maximum speed over the cardiac cycle in beralmingen - e.g. PASSENT APPLICATION NO 1200357-0 Brannstrom, Jansson, Marsal & Thuring3 (6) pulsatility index (PI) (Gosling et al., 1971). These indices eliminate the effect of the insonation angle by calculating a ratio. A time average velocity of the velocity (TAM) can be used when calculating volume flow. 2.2. Detailed Description and Application The invention is a non-invasive, standardized and objective method of characterizing the blood flow in blood vessels of the cardiovascular system. The invention is a specific signal processing algorithm applied to standardized Doppler ultrasound signals recorded from selected vessels, both arteries and veins. Today, fixed Fourier transform (FFT) is only applied at short time intervals to describe the distribution of blood velocities in the vessel, to calculate average or maximum velocity or to follow the velocity changes during the cardiac cycle. The latter is generally described with an index based on the measured maximum velocity waveform (pulsatility index). The invention applies FFT to a longer time window (at least one complete cycle, but at least two or more complete cardiac cycles) and different spectral properties are extracted to characterize the signal. By using this spectral content, the invention identifies the frequency band which contains the desired amount of spectral energy in the signal and the frequency band where the energy has fallen to a certain level. The advantage is that this method is easier to apply, more calculating efficient and more robust than current methods for assessing arterial flow (Thompson et al., 1986).
    The news value lies in the fact that the quantification of the Doppler shift's spectral contains Ors over a longer period of time, which results in a more robust mean value mat than what has been achieved with current methods.
    For example, during pregnancy, this method can be used to frequently analyze and quantify blood flow in the umbilical cord to evaluate the hemodynamic conditions in the placenta and fetus. By placing the Doppler transducer on the mother's stomach directly over the uterus, signals can be recorded from the umbilical artery. Pulsed Doppler ultrasound in combination with color Doppler is used and the size of the sample volume is chosen so that it covers the entire cross section of the vessel. The high-pass filter should be stalled as far as possible. Today, the blood flow in the umbilical artery is characterized by its pulsation which is due to the pumping movement of the fetal heart. When the function of the placenta is impaired, the river resistance increases and the amplitude of the pulsations increases. This is traditionally described with indices based on the calculated maximum PATENT APPLICATION NO 1200357-0 Brannstrom, Jansson, Marsal & Thuring4 (6) the flow velocity waveform. These indices are calculated either on-line by the ultrasound machine or off-line using a computer or manual evaluation. For the purposes of the present invention, the Doppler spectrum is stored both on the hard disk of the ultrasonic equipment and on a digital VCR supplemented with Doppler audio signals for further off-line analysis. By using the total spectral content in the recording of the Doppler spectrum over several cardiac cycles, the invention can be used to identify the frequency band which contains the highest spectral energy in the signal and the frequency band where the energy has fallen by 15 dB. As shown in animal models, these two mats, the frequency band with the highest energy and the frequency band where the energy had fallen by 15dB, are strongly correlated to the average speed (TAM). However, in clinical practice, TAM as calculated today is less reliable due to the above-mentioned methodological responsibilities (Thompson et al., 1986). Every new method is easier to apply, more calculating efficient and robust than today's calculating methods.
    权利要求:
    Claims (5)
    [1]
    The invention is a non-invasive method for characterizing blood flow in blood vessels of the cardiovascular system. The invention is a specific signal processing algorithm applied to standardized Doppler ultrasound signals of blood flow rates. The invention uses the Fast Fourier Transform on a time window lasting at least one complete cycle, but at least two or more complete cardiac cycles, and various spectral characteristics (such as frequency, energy and phase) which are extracted to characterize Doppler ultrasound signals. By using this spectral content, the invention identifies the frequency band which contains a defined amount of spectral energy in the signal and the frequency band where this energy has fallen to a certain level.
    [2]
    2. The invention can be used to characterize blood flow in blood vessels (including the heart) in the cardiovascular system of both humans and animals.
    [3]
    3. The invention can be used to diagnose the function of the cardiovascular system in humans (adults, children, fetuses) and animals under normal, physiological and pathological conditions.
    [4]
    4. The invention can be used to significantly improve the method of recording Doppler signals, since it can identify the best (lowest) angle of incidence to the blood flow in the vessel of the cardiovascular system, as the spectral content of the ultrasound signal varies by angle.
    [5]
    The invention can be used to describe the hemodynamic function of the cardiovascular system before, during and after surgical, pharmaceutical or other intervention.
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    同族专利:
    公开号 | 公开日
    SE537453C2|2015-05-05|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    SE1200357A|SE537453C2|2012-06-13|2012-06-13|Acoustic analysis and quantification of Doppler flow signals from the cardiovascular system|SE1200357A| SE537453C2|2012-06-13|2012-06-13|Acoustic analysis and quantification of Doppler flow signals from the cardiovascular system|
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