反转时间对流动敏感性交互反转恢复序列脊柱骨髓灌注成像的影响

Effect of inversion time on flow-sensitive alternating inversion recovery perfusion imaging of spinal bone marrow

目的 探讨反转时间（TI）对流动敏感性交互反转恢复（FAIR）序列脊柱骨髓灌注成像的影响,并评价该技术测量脊柱骨髓血流量（BF）的可重复性.方法 前瞻性收集24名经临床和腰椎MRI检查除外全身疾病和腰椎病变的健康志愿者进行观察.前14名志愿者行脊柱骨髓FAIR序列TI值优化研究,后10名志愿者行脊柱骨髓BF的可重复性研究.14名健康志愿者从L1～ L5椎体内选取2个相邻椎体行横断而FAIR扫描,TI值分别为800、1 000、1 200、1 400、1 600 ms,计算不同TI时椎体骨髓灌注的信号强度变化值（△M）和信噪比（SNR）.10名健康志愿者选取L4或L5椎体行2次FAIR序列扫描,参数相同（TI值为1 200 ms）,测量同一椎体前后2次FAIR扫描生成的BF值,并采用配对t检验及重复性分析评价2次测量的可重复性.结果 14名志愿者采用FAIR序列共扫描28个椎体,TI值分别为800、1 000、1 200、1 400、1 600 ms时,△M值分别为20.8±9.0、29.0± 10.9、36.4± 12.5、26.2±10.2和23.8±11.5,SNR分别为2.0±1.0、2.3±0.8、2.4±1.0、2.3±0.8和2.0±0.7,脊柱骨髓灌注△M值及SNR值,随TI值升高而呈现先升高后下降的趋势,TI为1 200 ms时达到高峰.10名志愿者前后2次扫描所得的椎体骨髓灌注的血流量BF值分别为（108.9±4.6）和（109.2±4.6）ml·10Og-1·min-1,差异无统计学意义（t=-0.157,P=0.879）.前后2次扫描间个体间变异系数wCV为3.28％（3.57/109.06）,可重复性良好.结论 TI值为1 200 ms时,脊柱椎体骨髓△M最大,灌注图像SNR最高,测量脊柱骨髓BF的可重复性好.

Objective To investigate the effect of inversion time （TI） on flow-sensitive alternating inversion recovery （FAIR） perfusion imaging of spinal bone marrow （SBM）,and evaluate the reproducibility of blood flow （BF） measurements using this technique.Methods Twenty four healthy volunteers without lumbar and other disease with clinical and MR studies were prospectively included.The first 14 healthy volunteers were included to study the effect of TI on ASL perfusion imaging of SBM to get the optimized TI,the remaining 10 volunteers were included to investigate the reproducibility of the SBM arterial spin labeling （ASL） scan protocol.The optimized TI of FAIR spinal bone marrow perfusion experiment was carried out on 14 healthy volunteers on 3.0 T magnet,two adjacent vertebral bodies were orderly selected from each volunteer to measure the △M and the SNR of FAIR perfusion MRI with 5 different TIs （800,1 000,1 200,1 400,1 600 ms）,and the vertebral bodies selected order were determined by the order of the subjects enrolled.In addition,FAIR perfusion spinal vertebral BF measurements were repeated in last l0 healthy subjects on L4 or L5 by reposition immediately,paired t test and reproducibility statistics （included within-patient standard deviation （wSD） and within-patient coefficient of variation （WCV）） were used to analyze the test-retest experiment reproducibility.Result TI optimization experiments total included 28 vertebral bodies,when TI （ms） was chose as 800,1 000,1 200,1 400,1 600,ms respectively,the mean △M of spinal bone marrow were 20.8±9.0,29.0± 10.9,36.4± 12.5,26.2± 10.2 and 23.8± 11.5,and the mean SNR were 2.0± 1.0,2.3±0.8,2.4± 1.0,2.3±0.8 and 2.0±0.7.With TI increasing,AM and SNR increased first and then decrcascd,the maximum values of both were achieved when the TI near 1 200 ms.Test-retestexperimcnt were carried on 10 vertebral bodies eventually,and two measurements of spinal vertebral BF perfusion before and after were （108.9±4.6）and （109.2 ±4.6）ml · 100g-1· min 1,respectively,and no significant difference was found （t=-0.157,P=0.879）,wCV of the measurements was 3.28％ （3.57/109.06）.Conclusion The optimal TI was 1 200 ms for spinal bone marrow ASL perfusion image,at which the maximum AM,higher SNR,and good reproducibility for the FAIR spinal bone marrow perfusion imaging can be achieved.