Frydrychowicz Alex, Bley Thorsten A, Winterer Jan T, Harloff Andreas, Langer Mathias, Hennig Jürgen, Markl Michael
Department of Diagnostic Radiology and Medical Physics, University Hospital Freiburg, Hugstetter Str. 55, 79106 Freiburg, Germany.
MAGMA. 2006 Sep;19(4):187-95. doi: 10.1007/s10334-006-0046-y. Epub 2006 Aug 26.
To evaluate whether time-resolved 3D MR-angiography at 3T with a net acceleration factor of eight is applicable in clinical routine and to evaluate whether good image quality and a low artifact level can be achieved with a temporal update rate that allows for additional information on pathologies.
Thirty-one consecutive patients underwent time-resolved 3D contrast-enhanced MR-angiography on a 3T system. Imaging consisted of accelerated 3D gradient echo sequences combining parallel imaging with an acceleration factor of four, partial Fourier acquisition along phase and slice encoding direction, and twofold temporal acceleration using view sharing. Data volumes representing the arterial and venous contrast phases were independently evaluated by two experienced radiologists by grading of image quality and artifact level on a 0-3 scale.
Time-resolved MR-angiography was successfully performed in all subjects without the need for contrast agent bolus timing. Excellent arterial (average score = 2.65 +/- 0.32) and good venous (average score = 2.56 +/- 0.28) diagnostic image quality and little image degrading due to artifacts (average score = 2.20 +/- 0.16) were confirmed by both independent readers (agreement in 65.2% of all evaluations). In 14 patients vascular pathologies were identified in the arterial phases. In eight examinations temporal resolution and depiction of contrast agent dynamics provided additional information about pathology.
Without the necessity for additional bolus timing, time-resolved 3D contrast-enhanced MR-angiography with imaging acceleration along both the spatial encoding direction and temporal domain revealed excellent diagnostic image quality in neurovascular and thoracic imaging. Despite the limited spatial resolution as compared to high-resolution imaging of the carotid artery bifurcation, the results demonstrate the applicability of contrast-enhanced MR-angiography in thoracic and abdominal MRA as well as cervical imaging with a temporal update rate allowing for additional information on pathologies. Future studies may include an evaluation of optimal trade-offs between spatial and temporal resolution, different acceleration factors and a comparison to the gold-standard for accuracy.
评估在3T场强下采用8倍净加速因子的时间分辨三维磁共振血管造影（MR - angiography）是否适用于临床常规检查，并评估在允许获取病变额外信息的时间更新率下，能否实现良好的图像质量和低伪影水平。
31例连续患者在3T系统上接受时间分辨三维对比增强磁共振血管造影检查。成像采用加速三维梯度回波序列，结合并行成像（加速因子为4）、沿相位和层面编码方向的部分傅里叶采集以及使用视图共享的两倍时间加速。两名经验丰富的放射科医生独立评估代表动脉期和静脉期对比剂增强的数据集，根据图像质量和伪影水平在0 - 3分的范围内进行评分。
所有受试者均成功完成时间分辨磁共振血管造影，无需对比剂团注定时。两位独立阅片者均证实动脉期诊断图像质量优异（平均评分 = 2.65 ± 0.32），静脉期良好（平均评分 = 2.56 ± 0.28），且伪影导致的图像质量下降较小（平均评分 = 2.20 ± 0.16）（在所有评估中一致性为65.2%）。14例患者在动脉期发现血管病变。在8次检查中，时间分辨率和对比剂动态显示为病变提供了额外信息。
无需额外的团注定时操作，沿空间编码方向和时间域进行成像加速的时间分辨三维对比增强磁共振血管造影在神经血管和胸部成像中显示出优异的诊断图像质量。尽管与颈动脉分叉的高分辨率成像相比空间分辨率有限，但结果表明对比增强磁共振血管造影在胸腹部磁共振血管造影以及颈部成像中的适用性，其时间更新率能够提供病变的额外信息。未来的研究可能包括评估空间和时间分辨率之间的最佳权衡、不同的加速因子以及与准确性金标准的比较。
