Baumgartner R W, Mattle H P, Aaslid R
Department of Neurology, University of Bern, Inselspital, Switzerland.
J Clin Ultrasound. 1995 Feb;23(2):89-111. doi: 10.1002/jcu.1870230205.
Transcranial color-coded duplex sonography (TCCD), magnetic resonance angiography (MRA), and computed tomography angiography (CTA) are novel noninvasive or minimally invasive techniques for the study of the intracranial circulation. TCCD is relatively inexpensive and permits bedside examination. It improves the accuracy and reliability of conventional transcranial Doppler studies. The main limitation of TCCD are the ultrasonic windows. They restrict the area of insonation to the major cerebral arteries and the proximal part of its branches, lower the spatial resolution, and may prevent transtemporal insonation. Using MRA, both large and small intracranial arteries and veins can be imaged by selecting the appropriate imaging parameters. MRA provides morphologic information about the cerebral vessels, relying on blood flow as the physical basis for generating contrast between stationary tissues and moving spins. MRA is highly sensitive for the detection of occlusive disease in large intracranial arteries. However, with bright blood techniques the degree of stenosis tends to be exaggerated. Flow direction, eg, in collaterals, can be determined by selective or phase-contrast MRA. Perfusion imaging techniques provide information about blood flow at the capillary level. Diffusion imaging depicts molecular motion. TCCD and MRA used in combination or alone may eliminate the need for intra-arterial digital subtraction angiography (DSA) in most patients studied for occlusive cerebrovascular disease. DSA may be reserved for those patients where there is disagreement among the noninvasive techniques, and for the diagnosis of cerebral aneurysms and arteriovenous malformations. CTA relies on spiral CT technology and intravenous contrast injection. To date, intracranial use has been predominantly for the diagnosis of aneurysms. The role of CTA for the detection of nonaneurysmal intracranial vascular disease has yet to be established.
经颅彩色编码双功超声检查（TCCD）、磁共振血管造影（MRA）和计算机断层血管造影（CTA）是用于研究颅内循环的新型非侵入性或微创技术。TCCD相对便宜，可在床边进行检查。它提高了传统经颅多普勒研究的准确性和可靠性。TCCD的主要局限性在于超声窗。它们将超声探测区域限制在大脑主要动脉及其分支的近端部分，降低了空间分辨率，并且可能妨碍经颞骨探测。使用MRA时，通过选择合适的成像参数，可以对颅内大、小动脉和静脉进行成像。MRA依靠血流作为在静止组织和移动自旋之间产生对比的物理基础，提供有关脑血管的形态学信息。MRA对检测颅内大动脉闭塞性疾病高度敏感。然而，使用亮血技术时，狭窄程度往往会被夸大。血流方向，例如侧支循环中的血流方向，可以通过选择性或相位对比MRA来确定。灌注成像技术提供有关毛细血管水平血流的信息。扩散成像描绘分子运动。在大多数研究闭塞性脑血管疾病的患者中，联合使用或单独使用TCCD和MRA可能无需进行动脉内数字减影血管造影（DSA）。DSA可保留用于那些非侵入性技术结果存在分歧的患者，以及用于诊断脑动脉瘤和动静脉畸形。CTA依靠螺旋CT技术和静脉注射造影剂。迄今为止，颅内CTA主要用于动脉瘤的诊断。CTA在检测非动脉瘤性颅内血管疾病中的作用尚未确立。
