Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Heidelberg University, Mannheim, Germany.
Invest Radiol. 2011 Nov;46(11):678-85. doi: 10.1097/RLI.0b013e31822428ad.
Comparison of 3 optimized pulse sequences for thoracoabdominal contrast-enhanced magnetic-resonance angiography by signal-to-noise measurements and time-dependent T1 mapping in the steady state after injection of 0.03 mmol/kg BW gadofosveset.
After institutional review board approval, 15 healthy volunteers (19-46 years, mean age: 31.5 years) were included in this prospective, intraindividual comparison study. All examinations were performed at 1.5 T. Three pulse sequences: volume interpolated breath-hold examination (VIBE) sequences as VIBESEMI (echo time [TE]: 1.64 milliseconds, repetition time [TR]: 3.77 milliseconds, FA: 15 degrees, voxel size: 1.2 × 1.2 × 1.2 mm) with short TR, VIBEOPT (TE: 2.2 milliseconds, TR: 5.2, FA: 15 degree, voxel size: 1.2 × 1.2 × 1.2 mm) with long TR, and a typical 3-dimensional fast low angle shot (FLASH) sequence (TE: 1.39 milliseconds, TR: 3.77 milliseconds, FA: 25 degree, voxel size: 1.0 × 0.8 × 1.0 mm) were repeated 10, 20, 30, and 40 minutes after the injection of 0.03 mmol/kg BW gadofosveset (mean dose: 9.7 mL). Mean signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were computed for the aorta and the inferior vena cava (IVC). Three-dimensional gradient echo sequences with variable flip angles were performed for T1 mapping 0 to 50 minutes postinjection (p.i.). Additional phantom measurements were performed to compare the sequences.
Significantly higher SNR values of the FLASH were found at every point compared with VIBEOPT (P = 0.002-P = 0.004), but only 10, respectively, 20 minutes p.i. to VIBESEMI. No significant differences of SNR were obtained between VIBESEMI and VIBEOPT. In the aorta, the maximal percentage gain of SNR was 29.2% for 3D-FLASH compared with VIBESEMI. Similar, but mostly not significant, results were obtained regarding the SNR in the IVC with the 3D-FLASH sequence yielding higher SNR versus both comparators (P = 0.007-P = 0.466). Except 10 minutes p.i., CNR analysis yielded higher values for the VIBESEMI versus both comparators in the aorta as well as in the IVC. No statistical significant difference was found for the VIBESEMI versus the 3D-FLASH sequence in all comparisons. Regarding the phantom measurements, statistically significant higher SNR was found for the VIBESEMI versus the 3D-FLASH. The T1 time in the aorta decreased p.i. from 1227 ± 383 milliseconds to 141 ± 27 milliseconds and showed over the time a slow reincrease to 175 ± 29 milliseconds at 50 minutes p.i.
Ten to 30 minutes after injection of gadofosveset, a relatively constant longitudinal relaxation is given. In this steady state, no additional improvements were obtained by theoretically optimized sequence parameters in the VIBEOPT with a longer TR.
通过注射 0.03mmol/kgBW 钆佛塞酯后稳态下的信号-噪声测量和时间依赖性 T1 映射比较 3 种优化的胸腹对比增强磁共振血管造影脉冲序列。
经机构审查委员会批准，15 名健康志愿者（19-46 岁，平均年龄：31.5 岁）参与了这项前瞻性、个体内比较研究。所有检查均在 1.5T 进行。三种脉冲序列：容积内插呼吸暂停检查（VIBE）序列，即 VIBESEMI（回波时间 [TE]：1.64 毫秒，重复时间 [TR]：3.77 毫秒，翻转角 [FA]：15 度，体素大小：1.2×1.2×1.2mm）具有较短的 TR、VIBEOPT（TE：2.2 毫秒，TR：5.2，FA：15 度，体素大小：1.2×1.2×1.2mm）具有较长的 TR，以及典型的三维快速低角度激发（FLASH）序列（TE：1.39 毫秒，TR：3.77 毫秒，FA：25 度，体素大小：1.0×0.8×1.0mm）在注射 0.03mmol/kgBW 钆佛塞酯后 10、20、30 和 40 分钟重复（平均剂量：9.7ml）。计算主动脉和下腔静脉（IVC）的平均信噪比（SNR）和对比噪声比（CNR）。在注射后 0 至 50 分钟（p.i.）进行三维梯度回波序列的可变翻转角 T1 映射。还进行了额外的体模测量，以比较序列。
与 VIBEOPT 相比，FLASH 的 SNR 值在每个时间点都显著升高（P=0.002-P=0.004），但只有 10 分钟和 20 分钟 p.i.时与 VIBESEMI 相比。VIBESEMI 和 VIBEOPT 之间没有得到显著的 SNR 差异。在主动脉中，与 VIBESEMI 相比，3D-FLASH 的 SNR 最大增益为 29.2%。在 IVC 中也获得了类似的，但大多不显著的 SNR 结果，与 VIBESEMI 相比，3D-FLASH 序列产生了更高的 SNR（P=0.007-P=0.466）。除了 10 分钟 p.i.外，在主动脉和 IVC 中，VIBESEMI 与两个比较器相比，CNR 分析的结果均显示出更高的 CNR 值。在所有比较中，VIBESEMI 与 3D-FLASH 序列之间均未发现统计学显著差异。关于体模测量，VIBESEMI 与 3D-FLASH 相比，SNR 统计学上更高。主动脉的 T1 时间从注射后 1227±383 毫秒下降到 141±27 毫秒，并在 50 分钟 p.i.时缓慢回升至 175±29 毫秒。
注射钆佛塞酯后 10-30 分钟，纵向弛豫时间相对稳定。在此稳定状态下，理论上优化的 VIBEOPT 序列参数具有较长的 TR，并没有获得额外的改善。
