The value of multi-source RF-transmission in balanced fast field echo cardiac cine imaging at 3.0 T magnetic resonance imaging / 中华放射学杂志

ABSTRACT

Objective To assess the advantages of multi-source RF transmission(MT) for balanced fast field echo(BFFE) cardiac cine imaging.Methods Fifteen volunteers were scanned on a clinical 3.0 T MR system equipped with MT.Acquisition of B1 maps with and without MT were followed by axial and four chambers BFFE cine imaging for all subjects with different transmission modes[single source RF transmission (ST),MT and MT with allowable shortest TR(MTS)].The B1 field uniformity and contrast to noise ratio (CNR) were quantitatively analyzed.The B1 field uniformity was evaluated by the pixel values within the ROI and was compared with Student t test.CNR was defined as follows(SIblood-SImyocardium)/ 0.5 ×(SDblood + SDmyocardium).CNR were tested with one-way ANOVA for three groups comparision and with LSD for inter-group comparison.Image qualities were blindly assessed by 2 readers with a 4-score scale.Global image quality scores were tested for statistical significance by using the nonparametric paired sample Friedman rank test for three groups and the Wilcoxon signed rank test for further inter-group comparison.The Kappa statistics was used to assess interreader agreement.Results B1 homogeneity was significantly improved for images with MT compared with ST under the condition of other parameters unchanged (t =21.632,P ＜0.01).In left ventricular,CNR of blood and myocardium was improved from 10.8 ±2.2 for ST to 14.4 ± 2.4 for MT and 14.1 ± 2.2 for MTS.In fight ventricular,it was improved from 7.7 ± 1.2 for ST to 12.2 ± 1.4 for MT and 12.0 ± 1.2 for MTS.The differences were statistically significant (F =11.617,61.472,P ＜0.01).The images of MT and MTS groups demonstrated greater CNR versus the ST images.There was no statistical difference between latter two groups.The image scores of Reader 1 and 2 were 4.60 ± 1.18 and 4.73 ± 1.10 for ST,6.53 ± 1.19 and 6.67 ± 1.29 for MT and 6.73 ± 1.03 and 6.73 ± 0.88 for MTS respectively.There were statistically differences among three groups (x2 =23.577,24.275,P ＜ 0.01).The image quality was improved on BFFE images using MT and MTS technology compared to ST technology,and there were also significant differences.The interreader agreement between two readers was good [K=0.643,0.722 and 0.814(P ＜0.05) for ST,MT,and MTS group respectively].Conclusions MT technology significantly improves B1 field uniformity,increases CNR and reduces artifact on BFFE cardiac cine images.The TR is decreased within the normal SAR ranges,and thus scanning speed is increased.