目的:体积各向同性同时交错的亮血和黑血检查(VISIBLE)可以同时获取血管信号抑制的图像(黑血图像)和无抑制的图像(亮血图像)。我们旨在通过调整k空间填充和使用启动回波来改善明亮的血液图像。
方法:常规可见中的亮血图像的k空间排列遵循从低到高频率的顺序,而在提议的可见序列中,顺序相反,并添加了启动回声。使用体模评估了启动回波对信噪比(SNR)的影响,考虑白质(WM)和对比后的血液。使用两个VISIBLE序列的常规方法和建议方法,以一维傅立叶变换模式从硫酸铜体模中获取数据。评价每个序列的信号行为。该研究包括14例患者,总共21例转移。对于每个病人来说,在施用造影剂后连续获得常规方法和建议方法的可见图像。使用临床图像,我们对肿瘤的信噪比和对比噪声比(CNR)进行了比较,正常WM,和血管之间的常规和建议的可见序列。
结果:传统序列和具有不同启动回波数量的拟议序列之间的黑血和亮血图像的SNR没有显着差异,然而,所提出的序列的SNR随着黑色和明亮图像中启动回波数量的增加而降低。当启动回波超过20时,亮血图像的信号行为达到“稳定状态”。亮血图像中血管的SNR在常规和提议的可见序列之间没有显着差异。在传统序列中,亮血图像中WM的SNR明显大于所提出的序列。在所提出的序列中,明亮血液图像中肿瘤的SNR明显大于常规序列。肿瘤和WM之间的CNR,在建议的序列中,明亮血液图像中的血管和WM明显高于常规序列。
结论:启动回波与高低频k空间排序方法的结合使用导致VISIBLE序列中明亮血液图像的CNR得到改善。
OBJECTIVE: A volume isotropic simultaneous interleaved bright- and black-blood examination (VISIBLE) can simultaneously acquire images with suppressed vascular signals (black-blood images) and images without suppression (bright-blood images). We aimed to improve of the bright-blood images by adjusting the k-space filling and using startup echo.
METHODS: The k-space arrangement of bright-blood images in the conventional VISIBLE followed a low-to-high frequency order, whereas that in the proposed VISIBLE sequence was in the reversed order, and a startup echo was added. The effects of startup echo on the signal-to-noise ratio (SNR) were evaluated using phantoms, considering both white matter (WM) and post-contrast blood. Data from copper sulfate phantoms were acquired in 1D Fourier transform mode using both the conventional and proposed methods of the two VISIBLE sequences. The signal behavior with each sequence was evaluated. Fourteen patients with a total of 21 metastases were included in the study. For each patient, VISIBLE images of both conventional and proposed methods were obtained consecutively after the contrast agent administration. Using clinical images, we conducted a comparison of the SNR and contrast-to-noise ratio (CNR) for tumors, normal WM, and blood vessels between the conventional and proposed VISIBLE sequences.
RESULTS: There was no significant difference in SNRs for both black- and bright-blood images between the conventional sequence and the proposed sequence with different number of startup echoes, however, the SNR of the proposed sequence decreased with increasing number of startup echoes in both black- and bright-images. The signal behavior of the bright-blood image reached a \"steady state\" when the startup echo exceeded 20. The SNRs of blood vessels in the bright-blood images did not differ significantly between conventional and proposed VISIBLE sequences. The SNRs of WM in the bright-blood images was significantly larger in the conventional sequence than in the proposed sequence. The SNRs of tumors in bright blood images was significantly larger in the proposed sequence than in the conventional sequence. The CNRs between tumors and WM, vessels and WM in the bright-blood images were significantly higher in the proposed sequence than in the conventional sequence.
CONCLUSIONS: The use of the startup echo in combination with the high-to-low frequency k-space ordering method resulted in improved CNR of the bright-blood images in the VISIBLE sequence.