Multi-pinhole single photon SPECT myocardial blood flow absolute quantification method and application

Multi-pinhole single photon SPECT myocardial blood flow absolute quantification method and application

  • CN 105,997,125 B
  • Filed: 06/15/2016
  • Issued: 09/17/2021
  • Est. Priority Date: 06/15/2016
  • Status: Active Grant
First Claim
Patent Images

1. A method for quantitative reconstruction of dynamic images and absolute quantitative measurement of myocardial blood flow of multi-pinhole SPECT or SPECT/CT removes interference of physical factors on the dynamic images through quantitative reconstruction of the images to obtain a time activity curve between a blood pool and myocardium, wherein the concentration of radioactivity is expressed in a unit Bq/ml;

  • using the blood pool and the myocardial activity curve to perform absolute quantitative calculation of myocardial blood flow, the method comprises the following steps;

    a nuclide physical decay correction step, which is carried out according to the starting time point, the acquisition time length and the acquired time of the dynamic SPECT99mHalf-life of Tc nuclide, calculating nuclide attenuation correction coefficient of each dynamic time point, thereby re-correcting radioactivity count which should be possessed in the original projection image;

    a patient movement correction step in scanning, wherein the dynamic SPECT images of each dynamic time point are used, the heart center is used as an origin, the boundary of a blood pool and cardiac muscle is found out through coordinate conversion, line tracking and geometric shape approximation, and the patient movement in scanning is corrected by obtaining a vector for correcting the patient movement by utilizing the maximum correlation;

    a scattering correction step, calculating the scattering component in the image by using a scattering energy window, and subtracting the scattering component image to obtain a scattering correction image;

    a geometric distortion correction step, wherein according to the geometric position of the pinhole and the probe corresponding to the center of the reconstructed image, in iterative reconstruction, the translation and coordinate conversion operation is carried out on the two forward rays through a front projection step and a back projection step so as to determine the correct position of the oblique rays on the probe and the reconstructed image, thereby correcting the geometric distortion of the reconstructed image caused by the oblique rays;

    a data truncation compensation step, wherein in the iterative image reconstruction process, the truncated area of the original projection image is estimated through the field range expansion and projection steps of the reconstructed image, the truncated area in the projection image of the reconstructed image is used for counting and butting the original image so as to expand the field range of the original image, and through the iterative process, the original image of the expanded field range is used as input to expand the range of the reconstructed image to be converged so as to compensate the artifact caused by data truncation;

    a tissue attenuation image generation step, converting the CT image into a tissue attenuation image, calculating an attenuation value of each ray by using a pinhole to irradiate the probe to create a tissue attenuation matrix, and correcting the underestimation of the drug uptake activity and the activity of other parts except the heart of the heart caused by the tissue attenuation by using the tissue attenuation matrix in iterative reconstruction so as to correct the tissue attenuation in the image;

    the image spatial resolution recovery step includes calculating the distance between a pixel of a reconstructed image and a pinhole according to a ray track according to rays from a probe penetrating the pinhole to the reconstructed image, establishing a diffusion function matrix according to the pinhole, and recovering the spatial resolution of pinhole imaging again by using the diffusion function matrix in iterative image reconstruction;

    a noise removing step, which is used in iterative image reconstruction through a wavelet filter to remove noise in the SPECT image;

    a pixel value conversion step of filling the prosthesis into the known one99mTc activity concentration of99mThe Tc decay process is subjected to multiple data acquisition and image reconstruction through the nuclide physical decay correction step, the patient movement correction step in scanning, the scattering correction step, the geometric distortion correction step, the data truncation compensation step, the tissue attenuation image generation step, the image spatial resolution recovery step and the noise removal step, and data analysis to obtain pixel values and absolute values99mThe linear relation of Tc activity concentration, and then convert the pixel value to the unit Bq/ml with physical meaning, thus obtain quantitative SPECT image;

    a myocardial blood flow quantitative calculation step;

    the quantitative multi-pinhole dynamic SPECT image is used for further carrying out dynamic activity measurement on blood pool and myocardial partObtaining a blood pool activity curve and a myocardial activity curve, and performing linear anastomosis on the curves through a physiological mathematical model with a single chamber to obtain three kinetic parameters of K1, K2 and K3, wherein the unit of K1 is ml/min/g, the unit of K2 is ml/min, the unit of K3 is ml/min, the rate of the drug entering myocardial cells is known from K1, and the rate of the drug entering the myocardial cells is obtained through the linear anastomosis of the curves through a physiological mathematical model with a single chamber99mThe uptake fraction of the Tc-labeled imaging drug was converted to K1 to obtain the absolute blood flow value, the cardiomyocyte rate of the imaging drug was obtained from K2, and the rate of the interaction of the imaging drug with the cardiomyocytes was known from K3.

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