Magnetic resonance imaging of the pancreas at 3.0 tesla - Qualitative and quantitative comparison with 7.5 tesla
Magnetic resonance imaging of the pancreas at 3.0 tesla - Qualitative and quantitative comparison with 7.5 tesla
复制标题
DOI：
10.1097/01.rli.0000195880.69880.6c
复制
发表时间：
2006-02-01
影响因子：
6.7
通讯作者：
Vu, A
中科院分区：
文献类型：
--
作者：
Edelman, RR;Salanitri, G;Vu, A
目的：我们试图进行初步比较的信噪比（SNR）和图像质量的磁共振成像（MRI）的胰腺在1.5和3 T。材料和方法：两个成像队列进行了研究，使用T2加权，单次快速自旋回波脉冲序列和T1加权，滤波抑制三维梯度回波脉冲序列。在第一个队列中，4名受试者在1.5和3.0 T的造影剂给药前后使用相同的成像参数进行成像。量化胰腺以及肝脏、脾脏和肌肉的SNR。在第二组12名受试者中，根据场强调整接收器带宽，进行SNR测量和图像质量的定性排名。在两种磁场强度下使用相同成像参数的研究队列中，胰腺、肝脏、脾脏、肌肉的平均值分别为1.63（0.39）、1.82（0.39）、1.45（0.18）、2.01（0.16）。对于对比前脂肪抑制3D梯度回波序列，相应的比率为1.28（0.29）、1.26（0.30）、1.16（0.27）和1.76（0.45），动脉期相应比值为2.02（0.28）、1.60（0.42）、1.47（0.26）和1.94（0.32）;对比后延迟期的相应比值分别为1.63（0.51）、2.01（0.25）、1.66（0.06）和2.31（0.47）。对比增强时，3.0 T的SNR优势明显大于非对比T1加权3D梯度回波图像。在第二个研究队列中，3.0 T时的SNR上级，尽管在1.5 T时使用降低的读出带宽大大降低了更高场系统的优势。通过对2种磁场强度下获得的图像进行定性比较，优选在3.0 T下获得的脂肪抑制3D梯度回波图像，而优选在1.5 T下获得的单次激发快速自旋回波图像，因为其信号均匀性更好。我们的结果在一小群志愿者和患者中显示，与1.5 T相比，3.0 T的SNR有显著改善当使用相同的成像参数时（在某些情况下为2倍）。3.0 T时的SNR优势有所减弱，但当接收器带宽针对磁场强度进行调整时，SNR优势仍然存在。结果表明，3.0 T可能为改善身体MRI提供了希望，尽管在实现其全部潜力之前需要进一步的技术开发以优化SNR并改善信号均匀性。
Objectives: We sought to perform a preliminary comparison of signal-to-noise ratio (SNR) and image quality for magnetic resonance imaging (MRI) of the pancreas at 1.5 and 3 T.Materials and Methods: Two imaging cohorts were Studied using a T2-weighted, single-shot fast spin-echo pulse sequence and a T1-weighted, filt-suppressed 3D gradient-echo pulse sequence. In the first cohort, 4 subjects were imaged using identical imaging parameters before and after contrast administration at 1.5 and 3.0 T. The SNR was quantified for the pancreas as well as for the liver, spleen, and muscle. In a second cohort of 12 Subjects in whom the receiver bandwidth was adjusted for field strength, SNR measurements and qualitative rankings of image quality were performed.Results: In the study cohort using identical imaging parameters at both magnetic field strengths, the mean (SID) ratios of SNR at 3.0 to 1.5 T of the single-shot flast spin-echo images for the pancreas, liver, spleen, and muscle were 1.63 (0.39), 1.82 (0.39), 1.45 (0.18), 2.01 (0.16), respectively. For the precontrast fat-suppressed 3D gradient-echo sequence, the corresponding ratios were 1.28 (0.29), 1.26 (0.30), 1.16 (0.27), and 1.76 (0.45), respectively; for the arterial phase, the corresponding ratios were 2.02 (0.28), 1.60 (0.42), 1.47 (0.26), and 1.94 (0.32), respectively; and for the delayed postcontrast phase, the corresponding ratios were 1.63 (0.5 1), 2.01 (0.25), 1.66 (0.06), and 2.31 (0.47), respectively. The SNR benefit of 3.0 T was significantly greater on contrast-enhanced as compared with noncontrast T1-weighted 3D gradient-echo images. In the second Study cohort, SNR was superior at 3.0 T, although the use of a reduced readout bandwidth at 1.5 T substantially diminished the advantage of the higher field system. With qualitative comparison of images obtained at the 2 magnetic field strengths, the fat-suppressed 3D gradient-echo images obtained at 3.0 T were preferred, whereas the single shot fast spin-echo images obtained at 1.5 T were preferred because of better signal homogeneity.Conclusions: Our results ill a small cohort of volunteers and patients demonstrate a marked improvement in SNR at 3.0 T compared with 1.5 T (by a factor of 2 in some cases) when identical imaging parameters were used. The SNR advantage at 3.0 T is diminished but persists when the receiver bandwidth is adjusted for magnetic field strength. The results suggest that 3.0 T may offer promise for improved body MRI, although further technical development to optimize SNR and improve signal homogeneity will be needed before its full potential call be achieved.