Low R N, Francis I R, Herfkens R J, Jeffrey R B, Glazer G M, Foo T K, Shimakawa A, Pelc N J
Department of Diagnostic Radiology and Nuclear Medicine, Stanford University Medical Center, CA 94305.
AJR Am J Roentgenol. 1993 Mar;160(3):501-9. doi: 10.2214/ajr.160.3.8381572.
The purpose of this study was to optimize a new rapid-acquisition MR pulse sequence, called fast multiplanar spoiled gradient-recalled (FMPSPGR) imaging, for breath-hold imaging of the liver and to compare unenhanced and contrast-enhanced FMPSPGR with standard spin-echo imaging in detecting liver tumors.
The pulse sequence was optimized at 1.5 T with a healthy volunteer. Various scanning parameters were evaluated, and liver-spleen signal difference/noise measurements were used to estimate lesion contrast-to-noise ratios. We examined 24 patients with hepatic masses using the optimized sequence with spin-echo T1-weighted and T2-weighted imaging as well as unenhanced and gadopentetate dimeglumine-enhanced FMPSPGR imaging. The contrast-to-noise ratio for the hepatic tumors was determined for each sequence. Three radiologists who did not know the biopsy or test results reviewed all images for lesion conspicuity, lesion tissue specificity, and overall image quality.
A comparison of unenhanced FMPSPGR images with spin-echo T1-weighted images showed a 40% improvement in mean contrast-to-noise ratio and a 70% improvement in liver signal-to-noise ratio for the FMPSPGR images. A comparison of gadopentetate dimeglumine-enhanced FMPSPGR images with spin-echo T1- and T2-weighted images showed a superior contrast-to-noise ratio for the enhanced FMPSPGR images in 17 (68%) of 25 hepatic lesions, which included all hepatic cysts (n = 3) and all hepatomas (n = 6), and in six of 12 patients with other liver tumors. The results of contrast-to-noise ratio for four patients with hemangiomas were mixed. For the remaining eight lesions, the contrast-to-noise ratio for spin-echo T1- and T2-weighted images predominated in three and five cases, respectively. Contrast-enhanced FMPSPGR images revealed a 40% and 300% increase in contrast-to-noise ratio compared with T2- and T1-weighted images, respectively. All three radiologists preferred the contrast-enhanced FMPSPGR images for overall image quality. For lesion conspicuity and specificity, however, the three radiologists differed, with a preference for the FMPSPGR images in 52%, 80%, and 40% of cases for lesion conspicuity and in 68%, 40%, and 60% of cases for lesion specificity.
FMPSPGR is a new, ultrafast MR sequence that provides T1-weighted images of the liver during suspended respiration. Contrast-to-noise ratio and liver signal-to-noise ratio are significantly improved over those on conventional spin-echo T1-weighted images. The combination of breath-hold FMPSPGR with gadopentetate dimeglumine is an excellent technique that can be used to rapidly evaluate the liver with superior overall image quality. Contrast-to-noise ratios are generally superior to T2-weighted spin-echo images, making this technique a useful adjunct to conventional spin-echo MR imaging.
本研究的目的是优化一种新的快速采集磁共振脉冲序列，即快速多平面扰相梯度回波（FMPSPGR）成像，用于肝脏屏气成像，并在检测肝脏肿瘤方面将未增强和对比增强的FMPSPGR与标准自旋回波成像进行比较。
使用一名健康志愿者在1.5T下对脉冲序列进行优化。评估了各种扫描参数，并使用肝脾信号差异/噪声测量来估计病变的对比噪声比。我们对24例肝脏肿块患者进行了检查，使用了优化后的序列以及自旋回波T1加权和T2加权成像，还有未增强和钆喷酸葡胺增强的FMPSPGR成像。确定了每个序列中肝脏肿瘤的对比噪声比。三位不知道活检或检测结果的放射科医生对所有图像进行了病变清晰度、病变组织特异性和整体图像质量的评估。
未增强的FMPSPGR图像与自旋回波T1加权图像相比，FMPSPGR图像的平均对比噪声比提高了40%，肝脏信噪比提高了70%。钆喷酸葡胺增强的FMPSPGR图像与自旋回波T1加权和T2加权图像相比，在25个肝脏病变中的17个（68%）中，增强的FMPSPGR图像具有更高的对比噪声比，其中包括所有肝囊肿（n = 3）和所有肝癌（n = 6），以及12例其他肝脏肿瘤患者中的6例。4例血管瘤患者的对比噪声比结果不一。对于其余8个病变，自旋回波T1加权和T2加权图像的对比噪声比在3例和5例中分别占优势。对比增强的FMPSPGR图像与T2加权和T1加权图像相比，对比噪声比分别提高了40%和300%。所有三位放射科医生在整体图像质量方面都更喜欢对比增强的FMPSPGR图像。然而，在病变清晰度和特异性方面，三位放射科医生存在差异，在病变清晰度方面，分别有52%、80%和40%的病例更喜欢FMPSPGR图像，在病变特异性方面，分别有68%、40%和60%的病例更喜欢FMPSPGR图像。
FMPSPGR是一种新的超快速磁共振序列，可在屏气期间提供肝脏的T1加权图像。与传统自旋回波T1加权图像相比，对比噪声比和肝脏信噪比显著提高。屏气FMPSPGR与钆喷酸葡胺的联合应用是一种优秀的技术，可用于快速评估肝脏，整体图像质量优异。对比噪声比通常优于T2加权自旋回波图像，使该技术成为传统自旋回波磁共振成像的有用辅助手段。
