Thierfelder Kolja M, Sommer Wieland H, Dietrich Olaf, Meinel Felix G, Theisen Daniel, Paprottka Philipp M, Strobl Frederik F, Pfeuffer Josef, Reiser Maximilian F, Nikolaou Konstantin
Department of Clinical Radiology, Ludwig-Maximilians-University of Munich Hospitals, Munich, Germany.
Department of Clinical Radiology, Ludwig-Maximilians-University of Munich Hospitals, Munich, Germany.
Eur J Radiol. 2014 Oct;83(10):1709-14. doi: 10.1016/j.ejrad.2014.06.006. Epub 2014 Jun 23.
To find out whether the use of accelerated 2D-selective parallel-transmit excitation MRI for diffusion-weighted EPI (pTX-EPI) offers advantages over conventional single-shot EPI (c-EPI) with respect to different aspects of image quality in the MRI of the pancreas.
The MRI examinations of 33 consecutive patients were evaluated in this prospective and IRB-approved study. PTX-EPI was performed with a reduced (zoomed) FOV of 230 × 118 mm(2). The 2D-RF pulse of pTX-EPI was accelerated, i.e. shortened by a factor of 1.7 (pTX-acceleration factor). C-EPI used a full-FOV of 380 × 285 mm(2). In a qualitative analysis, two experienced readers evaluated 3 different aspects of image quality on 3- to 5-point Likert scales. Additionally, apparent diffusion coefficients (ADCs) were determined in both c-EPI and pTX-EPI in normal-appearing pancreatic tissue using regions of interests (ROIs). Mean ADC values and standard deviations were compared between the two techniques.
The reduced-FOV pTX-EPI was superior to c-EPI with respect to overall image quality (p<0.0001) and identifiability of the pancreatic ducts (p<0.01). Artifacts were significantly less severe in pTX-EPI (p<0.01). The mean ADC values of c-EPI (1.29 ± 0.19 × 10(-3)mm(2)/s) and pTX-EPI (1.27 ± 0.17 × 10(-3)mm(2)/s) did not differ significantly between the two techniques (p=0.44). The variation within the ROIs as measured by the standard deviation was significantly lower in pTX-EPI (0.095 × 10(-3)mm(2)/s) than in c-EPI (0.135 × 10(-3)mm(2)/s), p<0.05.
PTX-accelerated EPI with spatially-selective excitation and reduced FOV leads to substantial improvements in DWI of the pancreas with respect to different aspects of image quality without significantly influencing the ADC values.
探讨在胰腺MRI中，采用加速二维选择性并行发射激发磁共振成像（pTX-EPI）进行扩散加权回波平面成像（DWI）相对于传统单次激发回波平面成像（c-EPI）在图像质量的不同方面是否具有优势。
在这项前瞻性且经机构审查委员会批准的研究中，对33例连续患者的MRI检查进行了评估。pTX-EPI采用缩小（缩放）视野，大小为230×118 mm²。pTX-EPI的二维射频脉冲被加速，即缩短了1.7倍（pTX加速因子）。c-EPI采用全视野380×285 mm²。在定性分析中，两位经验丰富的阅片者采用3至5分的李克特量表对图像质量的3个不同方面进行评估。此外，在c-EPI和pTX-EPI中，使用感兴趣区（ROI）在外观正常的胰腺组织中测定表观扩散系数（ADC）。比较了两种技术之间的平均ADC值和标准差。
在整体图像质量（p<0.0001）和胰管可识别性（p<0.01）方面，缩小视野的pTX-EPI优于c-EPI。pTX-EPI中的伪影明显较轻（p<0.01）。两种技术之间，c-EPI的平均ADC值（1.29±0.19×10⁻³mm²/s）和pTX-EPI的平均ADC值（1.27±0.17×10⁻³mm²/s）无显著差异（p=0.44）。pTX-EPI中通过标准差测量的ROI内的变异（0.095×10⁻³mm²/s）显著低于c-EPI（0.135×10⁻³mm²/s），p<0.05。
具有空间选择性激发和缩小视野的pTX加速EPI在胰腺DWI的图像质量不同方面带来显著改善，但对ADC值无显著影响。
