Trial of Signal-to-noise Ratio Adjustment by Repetition Time in Magnetic Resonance Imaging

Abstract

The purpose of this study was to find an equation between signal-to-noise ratio(SNR.) and repetition time (TR) in order to adjust SNR by changing TR in magnetic resonance imaging(MRl)examinations. Using a phantom for SNR measurement, according to NEMA MS 1-1988, measurement of SNR was performed by spin-echo pulse sequences for various TR values. An equation of SNR and scanning parameters include- ing TR were obtained from these results. In order to determine the range of TR where the images showed contrast suitable for diagnosis, the contrast-to-noise ratio(CNR) was measured for various TR values. CNR measurement was performed by scanning a brain phantom, and CNR was defined as the contrast of white matter and gray matter divided by noise. Scanning of a resolution phantom was carried out with various scanning parameters, and the usefulness of the equation obtained was determined by whether or not pins in the phantom were visible. The reliability of the equation was confirmed from this verification. Results showed that TR can be used for the adjustment of SNR using the equation obtained in this study.