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Magnetic Resonance Angiographic Evaluation of Circle of Willis in General Population: A Morphologic Study in 507 Cases



本研究之目的為利用未經顯影劑注射的三維航時磁振血管造影(Three-dimensional time-of-flight MR angiography, 3D-TOF-MRA)來評估以及描述威利氏環(Circle of Willis, Cow)的變異的型態及其盛行率。 實驗方式為回溯性的重新評估507位正常人的3D-TOF-MRA之威利氏環的影像。其中包括241位男性以及266位女性;年齡分佈在18-89歲之間。所有的檢查都是用同一台1.5T的磁振造影儀。威利氏環前方部分和後方部分的解剖學上的變異是利用最大強度投影(Maximal intensity projection)的影像來評估,同時也測量這些血管的主要部分的直徑。在這507個病人中,397(78.30%)個有完整的前方部份的威利氏環;129(25.44%)個病人有完整的後方部分的威利氏環;89(21.30%)位病人呈現出完整的威利氏環的結構。總共有十種前方及後方部分威利氏環的變異類型被確認出來。

Parallel abstracts

The purpose of this study is to evaluate and to describe the prevalence and pattern of circle of Willis (COW) arterial variants seen in non-contrasted three-dimensional time-of-flight MR angiography (3D-TOF-MRA) in a large series of patients. A review of the results of 507 consecutive normal subjects undergoing 3D-TOF- MRA of COW was performed retrospectively. There were 241 males and 266 females, aged from 18 to 89 years. A 1.5-T scanner was used in all these studies. The anatomic variants of anterior and posterior parts of the Circle of Willis were evaluated on maximal intensity projection (MIP) images and the diameters of its major constituents were measured. In these 507 cases, 397 (78.30%) cases have complete anterior parts of the COW; 129 (25.44%) cases have complete posterior parts of the COW and 89 (21.30%) cases demonstrate entire configuration of the Circle. Ten types of variations of anterior and posterior parts of the circle were recognized.