Nael K, Meshksar A, Ellingson B, Pirastehfar M, Salamon N, Finn P, Liebeskind D S, Villablanca J P
From the Department of Medical Imaging (K.N., A.M.), University of Arizona, Tucson, Arizona
From the Department of Medical Imaging (K.N., A.M.), University of Arizona, Tucson, Arizona.
AJNR Am J Neuroradiol. 2014 Jun;35(6):1078-84. doi: 10.3174/ajnr.A3848. Epub 2014 Feb 6.
There is need to improve image acquisition speed for MR imaging in evaluation of patients with acute ischemic stroke. The purpose of this study was to evaluate the feasibility of a 3T MR stroke protocol that combines low-dose contrast-enhanced MRA and dynamic susceptibility contrast perfusion, without additional contrast.
Thirty patients with acute stroke who underwent 3T MR imaging followed by DSA were retrospectively enrolled. TOF-MRA of the neck and brain and 3D contrast-enhanced MRA of the craniocervical arteries were obtained. A total of 0.1 mmol/kg of gadolinium was used for both contrast-enhanced MRA (0.05 mmol/kg) and dynamic susceptibility contrast perfusion (0.05 mmol/kg) (referred to as half-dose). An age-matched control stroke population underwent TOF-MRA and full-dose (0.1 mmol/kg) dynamic susceptibility contrast perfusion. The cervicocranial arteries were divided into 25 segments. Degree of arterial stenosis on contrast-enhanced MRA and TOF-MRA was compared with DSA. Time-to-maximum maps (>6 seconds) were evaluated for image quality and hypoperfusion. Quantitative analysis of arterial input function curves, SNR, and maximum T2* effects were compared between half- and full-dose groups.
The intermodality agreements (k) for arterial stenosis were 0.89 for DSA/contrast-enhanced MRA and 0.63 for DSA/TOF-MRA. Detection specificity of >50% arterial stenosis was lower for TOF-MRA (89%) versus contrast-enhanced MRA (97%) as the result of overestimation of 10% (39/410) of segments by TOF-MRA. The DWI-perfusion mismatch was identified in both groups with high interobserver agreement (r = 1). There was no significant difference between full width at half maximum of the arterial input function curves (P = .14) or the SNR values (0.6) between the half-dose and full-dose groups.
In patients with acute stroke, combined low-dose contrast-enhanced MRA and dynamic susceptibility contrast perfusion at 3T is feasible and results in significant scan time and contrast dose reductions.
在评估急性缺血性脑卒中患者时，需要提高磁共振成像（MR）的图像采集速度。本研究的目的是评估一种3T MR卒中检查方案的可行性，该方案结合了低剂量对比增强磁共振血管造影（MRA）和不使用额外对比剂的动态磁敏感对比灌注成像。
回顾性纳入30例接受3T MR成像检查并随后进行数字减影血管造影（DSA）的急性脑卒中患者。获取颈部和脑部的时间飞跃法（TOF）-MRA以及颅颈动脉的三维对比增强MRA。对比增强MRA（0.05 mmol/kg）和动态磁敏感对比灌注成像（0.05 mmol/kg）均使用总共0.1 mmol/kg的钆剂（称为半剂量）。年龄匹配的对照卒中人群接受TOF-MRA和全剂量（0.1 mmol/kg）动态磁敏感对比灌注成像。将颈颅动脉分为25段。对比增强MRA和TOF-MRA上的动脉狭窄程度与DSA进行比较。评估最大时间图（>6秒）的图像质量和灌注不足情况。比较半剂量组和全剂量组之间动脉输入函数曲线、信噪比（SNR）和最大T2*效应的定量分析结果。
动脉狭窄的不同检查方法间一致性（k值），DSA/对比增强MRA为0.89，DSA/TOF-MRA为0.63。由于TOF-MRA高估了10%（39/410）的节段，TOF-MRA检测>50%动脉狭窄的特异性（89%）低于对比增强MRA（97%）。两组均识别出弥散加权成像（DWI）-灌注不匹配，观察者间一致性较高（r = 1）。半剂量组和全剂量组之间动脉输入函数曲线的半高宽（P = 0.14）或SNR值（0.6）无显著差异。
在急性脑卒中患者中，3T下联合低剂量对比增强MRA和动态磁敏感对比灌注成像可行，可显著减少扫描时间和对比剂剂量。
