前瞻性3.0TMRI梯度多回波序列参数优化可行性研究

目的探讨缩短首回波(Minimum TE,TEmin)及扫描时间(Scan Time,ST)的3.0 T梯度多回波序列参数优化可行性。材料与方法在3.0 T扫描仪上,优化梯度多回波序列参数作为研究,与常规序列对照,分别扫描MR专用水模(含0~3.2 m M氯化锰盐酸混合液小瓶15只)、45例志愿者肝脏(包括重度铁沉积10例和非重度铁沉积35例),记录两序列TEmin和ST并由接受过良好培训的影像医师利用专业软件测算水模、肝T2*或R2*值。应用配对样本t检验或两相关样本非参数检验分析组间T2*值、TEmin和ST差异性,P0.05为差异有统计学意义;采用两变量相关分析与曲线拟合探讨水模R2*与其浓度相关性。结果 (1)水模、志愿者肝扫描两序列TEmin和ST组间差异有统计学意义(P=0.000),研究序列TEmin和ST分别为(0.62±0.02)ms、(9.3±0.8)s,与对照序列相比分别减少约53.0%、45.0%;(2)水模或志愿者肝扫描两序列间T2*差异在非重度铁沉积组无统计学意义(P水模/肝=0.814/0.201),而在重度铁沉积组有统计学差异(P=0.001),研究序列对重度铁沉积肝T2*检测可信度较高;(3)研究序列、重复及次月扫描水模各小瓶T2*值三组间差异无统计学意义(P=0.584),水模R2*与浓度(Ph C)高度线性相关(r=0.986,P=0.000),通过直线回归分析,得到Ph C与R2*拟合直线斜率和截距分别为7.008,0.036。结论在一定铁沉积浓度范围内,3.0 T MRI梯度多回波优化序列对活体肝扫描具有可行性,并提高重度铁过载检测可信度。

Feasibility of multiple-echo GRE with parameters optimized protocol at 3.0 T MRI

Objective: To explore the feasibility of 12-echo GRE with parameter optimized protocol at 3.0 T MRI by shortening minimum TE (TEmin) and scan time (ST). Materials and Methods:A MR special model which includes iffteen vials containing 0—3.2 mM manganese chloride in hydrochloric acid solution, 45 volunteer livers of 10 severe and 35 non-severe iron-overloaded patients were included in the study. 12-echo GRE sequence with parameter optimized at 3.0 Tesla unit was performed in our study and conventional protocol was executed in control group. T2* or R2* were quantiifed by a well-trained physician using a CMR tools or combining with EXCEL after MRI, TEmin and ST obtained from these two protocols were recorded respectively as well. Difference of values in T2*, TEmin and ST between the two groups were analyzed with SPSS 16.0 (Paired-Samplet test or Two Related Sample Test).P<0.05 has statistic significance. The correlation between R2* and phantom concentration (PhC) was analyzed by two-correlative-variable and curve-fitting.Results: Statistic differences were found for TEmin and ST value between the two groups (P=0.000), TEmin and ST value obtained from study protocol were (0.62±0.02) ms and (9.3±0.8) s, reduced by 53.0%, 45.0% comparing to control groups, respectively. For phantom and non-severe iron deposit livers, no statistic differences were found for T2* value between the two groups (Pphantom/liver=0.814/0.201). However, for severe iron deposit group, there was statistic difference between these two groups (P=0.001), also quantitativereliability of T2* value from study protocol was much better than control sequence. No statistic difference was found for T2* value among study sequence scan on phantoms, protocol repeating and next month scan (P=0.584). Phantom R2* was linearly correlated with its PhC (r=0.986,P=0.000). Through the regressions procedure, a slope of 7.008 and an intercept of 0.036 were found. Conclusions: Within a certain range of iron deposits, 12-echo GRE protocol with parameters optimized is feasible at 3.0 T MRI for both phantoms and in vivo livers. For severe hepatic iron deposit, measurement by 3.0 T MRI showed a better reliability.