Nederkoorn Paul J, van der Graaf Yolanda, Eikelboom Bert C, van der Lugt Aad, Bartels Lambertus W, Mali Willem P T M
Julius Center for Patient Oriented Research, University Medical Center Utrecht, the Netherlands.
AJNR Am J Neuroradiol. 2002 Nov-Dec;23(10):1779-84.
Time-of-flight (TOF) magnetic resonance angiography (MRA) is commonly used to visualize the carotid arteries; however, flow void artifacts can appear. Our purpose was to determine the frequency and diagnostic meaning of flow voids by using real patient data, as part of a larger study of MRA compared with the criterion standard, digital subtraction angiography (DSA).
In 1997-2000, 390 consecutive patients with sonographic findings suggestive of carotid artery stenosis were included in this study. All patients subsequently underwent three-dimensional (3D) TOF MRA and conventional DSA. The frequency of flow void artifacts on 3D TOF MRA images were compared with stenosis measurements on DSA images.
We recorded 107 flow voids (16%) during 3D TOF MRA of 662 carotid arteries. DSA images were available for comparison in 102 cases. The median percentage of stenosis in this subgroup of flow voids on MRA images was 80%, compared with measurements on DSA images according to the North American Symptomatic Carotid Endarterectomy Trial (NASCET) criteria. Stenoses ranged from 36% to 100% (occlusion). Three flow voids (2.9%) were in the 0-49% range; 11 (10.8%), in the 50-69% range; and 86 (84.3%), in the 70-99% range. Two flow voids (2.0%) represented occlusions. The positive predictive value of a flow void artifact for the presence of severe (70-99%) stenosis was 84.3% (95% CI: 77.3%, 91.4%).
Flow void artifacts represented severe stenosis in most of the arteries. According to our data, the assumption that flow voids on 3D TOF MRA images represent severe stenosis is justified.
时间飞跃法（TOF）磁共振血管造影（MRA）常用于可视化颈动脉；然而，可能会出现血流空洞伪影。我们的目的是通过使用真实患者数据来确定血流空洞的频率和诊断意义，这是一项将MRA与标准对照数字减影血管造影（DSA）进行比较的大型研究的一部分。
在1997 - 2000年期间，本研究纳入了390例连续的经超声检查发现提示颈动脉狭窄的患者。所有患者随后均接受了三维（3D）TOF MRA和传统DSA检查。将3D TOF MRA图像上血流空洞伪影的频率与DSA图像上的狭窄测量结果进行比较。
在对662条颈动脉进行3D TOF MRA检查期间，我们记录到107个血流空洞（16%）。102例患者有可供比较的DSA图像。根据北美症状性颈动脉内膜切除术试验（NASCET）标准，在这一血流空洞亚组中，MRA图像上狭窄的中位数百分比为80%，与DSA图像上的测量结果相比。狭窄范围为36%至100%（闭塞）。三个血流空洞（2.9%）在0 - 49%范围内；11个（10.8%）在50 - 69%范围内；86个（84.3%）在70 - 99%范围内。两个血流空洞（2.0%）代表闭塞。血流空洞伪影对于存在严重（70 - 99%）狭窄的阳性预测值为84.3%（95% CI：77.3%，91.4%）。
血流空洞伪影在大多数动脉中代表严重狭窄。根据我们的数据，3D TOF MRA图像上的血流空洞代表严重狭窄这一假设是合理的。
