Michaely Henrik J, Herrmann Karin A, Kramer Harald, Dietrich Olaf, Laub Gerhard, Reiser Maximilian F, Schoenberg Stefan O
Department of Clinical Radiology, University Hospitals-Grosshadern, Ludwig Maximilians University, Munich, Germany.
J Magn Reson Imaging. 2006 Jul;24(1):95-100. doi: 10.1002/jmri.20595.
To investigate the image quality and vessel depiction of renal MRA with integrated parallel imaging techniques (iPAT) using acceleration factors of 2 and 3.
In this prospective study renal MRA was performed on 14 and 12 patients with acceleration factors of 3 and 2, respectively. For the MRA a 3D-GRE sequence with an acquired spatial resolution of 0.9 x 0.8 x 1.0 mm(3) was applied (TR/TE = 3.79 msec/1.39 msec, FOV = 400 mm x 320 mm, acquired matrix = 512 x 384, flip angle = 25 degrees) on a 32-channel 1.5T MR scanner. The acquisition time was 26 seconds with iPAT 2, and 19 seconds with iPAT3. All parameters other than acquisition time and acceleration factor were kept constant. To assess the signal-to-noise ratio (SNR) we performed repetitive phantom measurements using iPAT 2 and 3. The images were rated by two radiologists in terms of noise, artifacts, and the quality of vessel depiction for the proximal, segmental, and subsegmental renal artery. A Mann-Whitney U-test and kappa-test were used for statistical analysis.
SNR decreased significantly with iPAT 3 in the phantom measurements. The two readers found no difference in noise, but significantly fewer artifacts with iPAT 3. The depiction of segmental vessels was significantly better for both readers with iPAT 3, and the subsegmental vessels were rated significantly better by one reader. iPAT 3 also resulted in a better interreader agreement.
The use of iPAT 3 for renal MRA enables a better depiction of the distal parts of the renal artery. The decrease in SNR is not diagnostically impairing.
研究采用加速因子为2和3的集成并行成像技术（iPAT）进行肾脏磁共振血管造影（MRA）时的图像质量和血管显示情况。
在这项前瞻性研究中，分别对14例和12例患者进行了加速因子为3和2的肾脏MRA检查。对于MRA，在一台32通道1.5T磁共振扫描仪上应用了三维梯度回波（3D-GRE）序列，采集空间分辨率为0.9×0.8×1.0 mm³（TR/TE = 3.79毫秒/1.39毫秒，视野 = 400毫米×320毫米，采集矩阵 = 512×384，翻转角 = 25度）。采用iPAT 2时采集时间为26秒，采用iPAT 3时为19秒。除采集时间和加速因子外，所有参数均保持不变。为评估信噪比（SNR），我们使用iPAT 2和3进行了重复性体模测量。两名放射科医生根据噪声、伪影以及肾动脉近端、节段性和亚节段性血管的显示质量对图像进行评分。采用Mann-Whitney U检验和kappa检验进行统计分析。
在体模测量中，采用iPAT 3时SNR显著降低。两位阅片者发现噪声无差异，但采用iPAT 3时伪影明显减少。对于两位阅片者而言，采用iPAT 3时节段性血管的显示明显更好，一位阅片者对亚节段性血管的评分也明显更高。iPAT 3还导致阅片者之间的一致性更好。
在肾脏MRA中使用iPAT 3能够更好地显示肾动脉的远端部分。SNR的降低在诊断上并无损害。
