Sheppard S, Davis P C, Kater G, Peterson J E
Department of Radiology, Frederik Philips MR Research Center, Emory University School of Medicine, Atlanta, GA, USA.
AJNR Am J Neuroradiol. 1998 Feb;19(2):267-73.
A T1-weighted multishot inversion-recovery (IR) echo-planar MR imaging (EPI) sequence was developed to improve intracranial tissue differentiation; its diagnostic utility was compared with that of conventional axial T1-weighted spin-echo and axial T2-weighted turbo spin-echo sequences.
Eighteen patients with known or suspected primary or metastatic brain neoplasia were imaged in a 1.5-T unit with IR-EPI sequences. Three observers measured gray/white matter contrast-to-noise ratios and subjectively compared IR-EPI sequences with T1-weighted spin-echo and T2-weighted turbo spin-echo sequences for gray/white matter discrimination, visibility of intracranial and vascular structures, overall lesion conspicuity, size of lesion(s), and presence and severity of artifacts.
Twenty-four lesions (including neoplasia, infarction, treatment-associated encephalomalacia, nonneoplastic white matter signal abnormalities, and basilar artery dolichoectasia) were detected in 12 patients. Basilar artery dolichoectasia was not included in subsequent statistical analysis. Pulsatile flow artifacts were markedly reduced on IR-EPI sequences relative to those on T1-weighted spin-echo sequences. Gray/white matter contrast was greater on IR-EPI images than on T1-weighted spin-echo images. Periaqueductal gray matter, basal ganglia, optic tracts, cranial nerve V, and claustrum were seen better or as well on IR-EPI images as compared with T1-weighted spin-echo images. IR-EPI was more sensitive to magnetic sensitivity effects, with resultant decreased visibility of cranial nerves VII and VIII and the orbital portion of the optic nerves. For noncontrast sequences, lesion conspicuity was better on IR-EPI images than on T1-weighted spin-echo images in 16 (70%) of 23 lesions and was equal on the two sequences in seven (30%) of 23 lesions. Lesion size, including surrounding edema, was greater on IR-EPI images than on T2-weighted turbo spin-echo images in two (9%) of 23 cases and equal in 21 (91%) of 23 cases. Hyperintense foci of methemoglobin were more conspicuous on T1-weighted spin-echo images.
Multishot IR-EPI is superior to conventional T1-weighted spin-echo imaging for parenchymal tissue contrast and lesion conspicuity, and is equal to T2-weighted turbo spin-echo imaging in sensitivity to pathologic entities.
开发一种T1加权多激发反转恢复（IR）回波平面磁共振成像（EPI）序列以改善颅内组织的分辨能力；并将其诊断效用与传统的轴向T1加权自旋回波序列和轴向T2加权快速自旋回波序列进行比较。
18例已知或疑似原发性或转移性脑肿瘤的患者在1.5-T设备上采用IR-EPI序列进行成像。三名观察者测量灰质/白质对比噪声比，并主观地将IR-EPI序列与T1加权自旋回波序列和T2加权快速自旋回波序列进行比较，以评估灰质/白质的辨别能力、颅内和血管结构的可视性、整体病变的清晰度、病变大小以及伪影的存在和严重程度。
在12例患者中检测到24个病变（包括肿瘤、梗死、治疗相关的脑软化、非肿瘤性白质信号异常和基底动脉延长扩张）。基底动脉延长扩张未纳入后续统计分析。相对于T1加权自旋回波序列，IR-EPI序列上的搏动性血流伪影明显减少。IR-EPI图像上的灰质/白质对比大于T1加权自旋回波图像。与T1加权自旋回波图像相比，中脑导水管周围灰质、基底神经节、视束、三叉神经和屏状核在IR-EPI图像上显示得更好或相同。IR-EPI对磁敏感性效应更敏感，导致面神经VII和VIII以及视神经眶内部分的可视性降低。对于非增强序列，23个病变中有16个（70%）在IR-EPI图像上的病变清晰度优于T1加权自旋回波图像，23个病变中有7个（30%）在两种序列上相同。23例中有2例（9%）的病变大小（包括周围水肿）在IR-EPI图像上大于T2加权快速自旋回波图像，23例中有21例（91%）相同。高铁血红蛋白的高信号灶在T1加权自旋回波图像上更明显。
多激发IR-EPI在实质组织对比度和病变清晰度方面优于传统的T1加权自旋回波成像，在对病理实体的敏感性方面与T2加权快速自旋回波成像相当。
