| 摘要 |
The present invention provides a technique for obtaining a high-quality image at high speed in DKI analysis. In the DKI analysis, upon estimating a parameter relating to diffusion in an application direction of an MPG pulse, a least square fitting is separated from a constraint processing, and only a value of the pixel that does not meet the constraint condition in the least square fitting is targeted for the correction. Then, with regard to this pixel, a diffusion-related parameter is re-estimated using the pixel value after the correction, and a parameter image is generated by using the diffusion-related parameter thus obtained. |
| 主权项 |
1. A magnetic resonance imaging apparatus comprising,
an imager configured to perform measurement according to a pulse sequence being predetermined, and reconstruct an image, and an image processor configured to subject the image being reconstructed to an arithmetic processing, and obtain a parameter image, the pulse sequence being a diffusion weighted imaging sequence that applies an MPG (motion probing gradient) pulse, the MPG pulse being configured to add signal variation along with diffusion as a gradient magnetic field to a nuclear magnetic resonance signal, wherein, the imager executes the pulse sequence with varying an application direction and a b-value of the MPG pulse so as to acquire plural images, and the image processor comprises, an ROI setter configured to set a region of interest on the image, a parameter estimator configured to estimate a diffusion parameter being a diffusion-related parameter with respect to each pixel, by using a value of the pixel in the region of interest of the plural images obtained by executing the pulse sequence, setting the application direction of the MPG pulse to be identical and varying the b-value, a discriminator configured to make a determination whether or not the diffusion parameter being estimated is within a predetermined range, a pixel value corrector configured to perform correction on the value of the pixel as to which the a result of the determination indicates the diffusion parameter is out of the range, and an image generator configured to generate the parameter image by using the diffusion parameter for each pixel, wherein, the parameter estimator estimates the diffusion parameter according to a least square fitting without a constraint condition, and re-estimates the diffusion parameter by using the value of the pixel after the correction for the pixel as to which the result of the determination indicates the diffusion parameter is out of the range, and the image generator uses the diffusion parameter being re-estimated for the pixel the value of which is corrected. |
