Morelli John, Porter David, Ai Fei, Gerdes Clint, Saettele Megan, Feiweier Thorsten, Padua Abraham, Dix James, Marra Michael, Rangaswamy Rajesh, Runge Val
Scott & White Memorial Hospital/Texas A&M Health Sciences Center, Radiology, Temple, TX, USA.
Acta Radiol. 2013 Apr 1;54(3):299-306. doi: 10.1258/ar.2012.120541. Epub 2013 Jan 14.
Diffusion-weighted imaging (DWI) magnetic resonance imaging (MRI) is most commonly performed utilizing a single-shot echo-planar imaging technique (ss-EPI). Susceptibility artifact and image blur are severe when this sequence is utilized at 3 T.
To evaluate a readout-segmented approach to DWI MR in comparison with single-shot echo planar imaging for brain MRI.
Eleven healthy volunteers and 14 patients with acute and early subacute infarctions underwent DWI MR examinations at 1.5 and 3T with ss-EPI and readout-segmented echo-planar (rs-EPI) DWI at equal nominal spatial resolutions. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) calculations were made, and two blinded readers ranked the scans in terms of high signal intensity bulk susceptibility artifact, spatial distortions, image blur, overall preference, and motion artifact.
SNR and CNR were greatest with rs-EPI (8.1 ± 0.2 SNR vs. 6.0 ± 0.2; P <10(-4) at 3T). Spatial distortions were greater with single-shot (0.23 ± 0.03 at 3T; P <0.001) than with rs-EPI (0.12 ± 0.02 at 3T). Combined with blur and artifact reduction, this resulted in a qualitative preference for the readout-segmented scans overall.
Substantial image quality improvements are possible with readout-segmented vs. single-shot EPI - the current clinical standard for DWI - regardless of field strength (1.5 or 3 T). This results in improved image quality secondary to greater real spatial resolution and reduced artifacts from susceptibility in MR imaging of the brain.
扩散加权成像（DWI）磁共振成像（MRI）最常采用单次激发回波平面成像技术（ss-EPI）进行。当在3T使用该序列时，磁敏感伪影和图像模糊很严重。
与单次激发回波平面成像相比，评估一种读出分段方法用于脑部MRI的DWI MR。
11名健康志愿者和14名急性及早期亚急性梗死患者在1.5T和3T下接受DWI MR检查，采用ss-EPI和读出分段回波平面（rs-EPI）DWI，两者具有相同的标称空间分辨率。计算信噪比（SNR）和对比噪声比（CNR），两名盲法阅片者根据高信号强度的整体磁敏感伪影、空间畸变、图像模糊、总体偏好和运动伪影对扫描图像进行排序。
rs-EPI的SNR和CNR最高（3T时SNR为8.1±0.2，而单次激发为6.0±0.2；P<10⁻⁴）。单次激发的空间畸变（3T时为0.23±0.03；P<0.001）比rs-EPI（3T时为0.12±0.02）更大。结合模糊和伪影减少，总体上导致对读出分段扫描的定性偏好。
与单次激发EPI（目前DWI的临床标准）相比，读出分段可显著提高图像质量，无论场强是1.5T还是3T。这导致图像质量提高，这是由于更高的实际空间分辨率以及脑部MR成像中磁敏感伪影减少。
