Rice and perfluorocarbon liquid pads: comparison of fat suppression effects

With the chemical shift selective (CHESS) method, lingering fat signals remain because of the effects of nonuniformity in the magnetic field. One method to reduce this phenomenon is the use of pads filled with rice (rice pad), but the improvement in fat suppression effects with rice pads, as compared with conventional perfluorocarbon liquid pads, remains unclear.

To investigate whether rice pads are superior to perfluorocarbon liquid pads in improving fat suppression effects in magnetic resonance imaging (MRI) examination of the knee.

Subjects were 10 healthy volunteers (5 men, 5 women; aged 20-45 years), from whom images taken using the CHESS methods were collected. Two images were taken for each subject; one with a rice pad placed under the knee and the knee flexed, and the other with a perfluorocarbon liquid pad placed under the knee and the knee flexed. Images were visually assessed by one radiologist and one radiologic technologist. Kendall's W and Wilcoxon signed rank test were used for statistical comparisons.

Of the 20 evaluations made by the 2 observers, scores for images obtained with the rice pad were higher than those with the perfluorocarbon liquid pad in 18 cases, while the scores were equal in 2 cases. Images with the rice pad were not inferior in any cases. The mean score for visual assessment was 4.65 for the rice pad and 3.0 for the perfluorocarbon liquid pad. The rice pad was thus confirmed to be superior to the perfluorocarbon liquid pad (P=0.0039).

The rice pad exhibited better performance in improving the fat suppression effect. Thus, the rice pad is a superior product that is inexpensive and simple to use.