Fondazione G Monasterio CNR-Regione Toscana and Institute of Clinical Physiology, Pisa, Italy.
Magn Reson Med. 2011 Dec;66(6):1731-8. doi: 10.1002/mrm.22969. Epub 2011 Jun 23.
Myocardial perfusion images can be affected by the dark rim artifact. This study aimed to evaluate the effects of the spatial resolution and heart rate on the transmural extent of the artifact. Six pigs under anesthesia were scanned at 1.5T using an echo-planar imaging/fast gradient echo sequence with a nonselective saturation preparation pulse. Three short-axis slices were acquired every heart beat during the first pass of a contrast agent bolus. Two different in-plane spatial resolutions (2.65 and 3.75 mm) and two different heart rates (normal and tachycardia) were used, generating a set of four perfusion scans. The percentage drop of signal in the subendocardium compared to the epicardium and the transmural extent of the artifact were extracted. Additionally, the signal-to-noise and the contrast-to-noise ratios were evaluated. The signal drop as well as the width of the dark rim artifact increased with decreased spatial resolution and with increased heart rates. No significant slice-to-slice variability was detected for signal drop and width of the rim within the four considered groups. signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) ratios decreased with increasing spatial resolution. In conclusion, low spatial and temporal resolution could be correlated with increased extent of the dark-rim artifact and with lower SNR and CNR.
心肌灌注图像可能会受到暗边伪影的影响。本研究旨在评估空间分辨率和心率对伪影贯穿程度的影响。六头麻醉猪在 1.5T 下使用回波平面成像/快速梯度回波序列进行扫描，采用非选择性饱和准备脉冲。在对比剂团注的第一次通过期间，每搏采集三个短轴切片。使用两种不同的平面内空间分辨率（2.65 和 3.75mm）和两种不同的心率（正常和心动过速），生成一组四个灌注扫描。提取心内膜下信号与心外膜信号的百分比下降以及伪影的贯穿程度。此外，还评估了信号噪声比和对比噪声比。随着空间分辨率的降低和心率的增加，信号下降以及暗边伪影的宽度增加。在四个考虑的组内，未检测到信号下降和边缘宽度的切片间变异性。信号噪声比（SNR）和对比噪声比（CNR）随着空间分辨率的增加而降低。总之，低空间和时间分辨率可能与暗边伪影的范围增加以及 SNR 和 CNR 降低有关。
