MR Influence Of Different Field Strength And Different Scanner With Same Field On Quantitative For Lumbar Bone Marrow Fat Content With In-phase And Opposed-phase In Healthy Volunteers

Objective: To investigate the effect of quantitative analysis for lumbar vertebral bone marrow fat content in healthy volunteers by using in-phase and opposed-phase chemical shift imaging at 3.0 T vs 1.5 T、1.5 T of different scanners and at different scanning flip angle(FA).Materials and Methods: A total of 32 cases of healthy volunteers were examined with both traditional lumbar spine protocol(fast spin-echo [FSE] T1-weighted, T2-weighted sagittal) and in – phase and opposed – phase imaging by using Seimens 3.0T, GE 1.5T, Toshiba 1.5T MR scanners. 1.5 T MR flip angle choose 70 °, 3.0 T MR flip Angle respectively choose 10 °、30 °、50 °、70 °, the total 4 groups of different flip Angle.A rectangle region of interest measurement of the signal intensity was made on the central of vertebral on the in-phase as well as on the opposed-phase images. The signal intensity decrease in the lumbar vertebral on the opposed-phase to signal intensity was calculated by the formula: SII =[(SIIP – SIOP)/(SI IP)]×100%. The SII were compared between different magnetic field and different scanners on the same magnetic field and different FA.Results: The mean SII of lumbar vertebral at Seimens3.0T, GE1.5T and Toshiba1.5T were(70.9 + 5.4) %,(71.2 + 8.4) % and(71.5 + 8.1) % respectively. From the aspect of different field strength MR scanners, there were no significant differences in SII of lumbar vertebral(Siemens3.0T vs GE1.5T t = 0.498, P > 0.05, Siemens3.0T vs Toshiba1.5T t= 0.881, P>0.05). From the aspect of the same field of different scanners(Toshiba1.5T and GE1.5 T) there were no significant differences in SII of lumbar vertebral(t= 0.489, P > 0.489). The same anatomical level lumbar vertebral SII there was no significant difference in three different MR(P > 0.05),SII at different level lumbar vertebral were no significant differences(P > 0.05). Siemens 3.0 T showed the tendency of lumbar vertebral SII increasing with FA increasing, there were significant differences between different FA(F = 36.929, P﹤36.929), there were no significant differences between group 50 ° and group 70 °(P = 0.116 st13 0.05), there were significant differences between other groups(P﹤0.05).Conclusion:1. Quantitative analysis for lumbar vertebral fat content of healthy volunteers with in-phase and opposed-phase chemical shift imaging in different field MR and different scanners of the same field strength MR may be comparable.2. Different anatomical level lumbar vertebral bone marrow fat content of healthy volunteers has no obvious difference.3. scanning FA have a certain impact on lumbar vertebral marrow fat quantitative of healthy volunteers, big FA(50 °, 70 °) has better stability for lumbar vertebral bone marrow fat quantitative.