The number of data points collected in one, two or all three directions. Normally used for the 2D in plane sampling. The display matrix may be different from the acquisition matrix, although the latter determines the resolution. Measurement time may be saved by not acquiring raw data lines corresponding to high resolution. Not measured rows are filled with zeroes prior to the image calculation. A square image is the result of an interpolation in phase encoding direction. See also Zero Filling.

The chosen matrix size effects scan time, resolution and SNR. Reduced measurement matrixes decrease the scan time and the resolution by increased SNR.

Resolution is a function of slice thickness, field of view (FOV) and matrix size. The resolution in plane is a function of FOV / matrix size.

A method of interpolating image data by zero filling the high spatial-frequency components of the raw data so that after Fourier transformation the image matrix size has been increased. This method can significantly improve the image display.

Substitution of zeroes for unmeasured data points in order to increase the matrix size of the new data prior to Fourier transformation of MR data. This can be equivalent to performing an interpolation (ZIP - zero fill interpolation processing) in the transformed data, resulting in pixels smaller than the actual resolution of the image.

From Hitachi Medical Systems America, Inc.;
the AIRIS made its debut in 1995. Hitachi followed up with the AIRIS II system, which has proven equally successfully. 'All told, Hitachi has installed more than 1,000 MRI systems in the U.S., holding more than 17 percent of the total U.S. MRI installed base, and more than half of the installed base of open MR systems,' says Antonio Garcia, Frost and Sullivan industry research analyst. Now Altaire employs a blend of innovative Hitachi features called VOSI™ technology, optimizing each sub-system's performance in concert with the other sub-systems, to give the seamless mix of high-field performance and the patient comfort, especially for claustrophobic patients, of open MR systems.