Leach J L, Jones B V, Tomsick T A, Stewart C A, Balko M G
Department of Radiology, University of Cincinnati (Ohio) Hospital, USA.
AJNR Am J Neuroradiol. 1996 Sep;17(8):1523-32.
To determine the imaging appearance and frequency with which arachnoid granulations are seen on contrast-enhanced CT and MR studies of the brain.
We retrospectively reviewed 573 contrast-enhanced CT scans and 100 contrast-enhanced MR studies of the brain for the presence of discrete filling defects within the venous sinuses. An anatomic study of the dural sinuses of 29 cadavers was performed, and the location, appearance, and histologic findings of focal protrusions into the dural sinus lumen (arachnoid granulations) were assessed and compared with the imaging findings.
Discrete filling defects within the dural sinuses were found on 138 (24%) of the contrast-enhanced CT examinations. A total of 168 defects were found, the majority (92%) within the transverse sinuses. One third were isodense and two thirds were hypodense relative to brain parenchyma. Patients with filling defects were older than patients without filling defects (mean age, 46 years versus 40 years). Discrete intrasinus signal foci were noted on 13 (13%) of the contrast-enhanced MR studies. The foci followed the same distribution as the filling defects seen on CT scans and were isointense to hypointense on T1-weighted images, variable in signal on balanced images, and hyperintense on T2-weighted images. Transverse sinus arachnoid granulations were noted adjacent to venous entrance sites in 62% and 85% of the CT and MR examinations, respectively. Arachnoid granulations were found in 19 (66%) of the cadaveric specimens, in a similar distribution as that seen on the imaging studies.
Discrete filling defects, consistent with arachnoid granulations, may be seen in the dural sinuses on 24% of contrast-enhanced CT scans and on 13% of MR studies. They are focal, well-defined, and typically located within the lateral transverse sinuses adjacent to venous entrance sites. They should not be mistaken for sinus thrombosis or intrasinus tumor, but recognized as normal structures.
确定在脑部增强CT和MR研究中蛛网膜颗粒的影像表现及出现频率。
我们回顾性分析了573例脑部增强CT扫描和100例脑部增强MR研究，以观察静脉窦内是否存在离散性充盈缺损。对29具尸体的硬脑膜窦进行了解剖学研究，并评估了硬膜窦腔内局灶性突出（蛛网膜颗粒）的位置、表现和组织学发现，并与影像学结果进行比较。
在138例（24%）增强CT检查中发现硬脑膜窦内有离散性充盈缺损。共发现168个缺损，大多数（92%）位于横窦内。相对于脑实质，三分之一为等密度，三分之二为低密度。有充盈缺损的患者比无充盈缺损的患者年龄大（平均年龄，46岁对40岁）。在13例（13%）增强MR研究中发现了离散性窦内信号灶。这些病灶的分布与CT扫描上的充盈缺损相同，在T1加权图像上呈等信号至低信号，在平衡图像上信号可变，在T2加权图像上呈高信号。在CT和MR检查中，分别有62%和85%的横窦蛛网膜颗粒位于静脉入口部位附近。在19例（66%）尸体标本中发现了蛛网膜颗粒，其分布与影像学研究相似。
在24%的增强CT扫描和13%的MR研究中，硬脑膜窦内可出现与蛛网膜颗粒一致的离散性充盈缺损。它们是局灶性的，边界清晰，通常位于外侧横窦内靠近静脉入口部位。不应将它们误诊为窦血栓形成或窦内肿瘤，而应视为正常结构。
