Magnetic Resonance Imaging Measurements of Optic Sheath to Optic Nerve Diameter Ratio for the Diagnosis of Idiopathic Intracranial Hypertension
SS Lingawi
Hong Kong J Radiol 2010;12:103-6
Objective: To evaluate the usefulness of optic sheath–optic nerve diameter ratio for the diagnosis of idiopathic intracranial hypertension.
Methods: This study included 45 patients with idiopathic intracranial hypertension and 19 healthy volunteers as a control population. Magnetic resonance imaging of the orbits was performed in a 1.5T magnetic resonance imaging system using a standard non-enhanced magnetic resonance imaging orbital protocol, including 3-mm axial, sagittal, and coronal T1- and T2-weighted images, with and without fat-saturation using a conventional coil. The optic sheath and optic nerve diameters were measured using the outer diameter of the subarachnoid space and nerve at the point of maximum optic sheath distension. Correlation with the respective lumbar puncture opening pressure was made for the patient population.
Results: Among the control group, 88.6% had optic sheath–optic nerve diameter ratios of <2:1 and 11.4% had optic sheath–optic nerve ratios ≥2.5:1. All patients with idiopathic intracranial hypertension had optic sheath– optic nerve ratios ≥2.5:1.
Conclusions: Optic sheath–optic nerve diameter ratio is useful for the diagnosis of idiopathic intracranial hypertension. Ratios ≥2.5:1 have a high correlation with increased intracranial pressure.
中文摘要
磁共振成像測量視神經鞘直徑與視神經直徑比值應用於診斷原發性顱內高壓
SS Lingawi
目的：探討視神經鞘直徑與視神經直徑比值在診斷原發性顱內高壓的價值。
方法：研究納入45例原發性顱內高壓患者，以及19例健康志願者作為對照組。所有研究對象均在 1.5T核磁掃描儀上行標准眼眶序列檢查；包括T1加權和T2加權成像，均含軸位，矢狀位及冠狀位； 序列檢查含脂肪抑制及無脂肪抑制技術；所有檢查均使用普通線圈，均未注射造影劑。在神經鞘直 徑最大處分別測量視神經鞘外蛛網膜下腔的直徑和視神經直徑。對每個研究對象的視神經鞘與視神 經直徑比值和腰穿測得的壓力進行相關性分析。
結果：在對照組，88.6%的研究對象視神經鞘與視神經直徑比值為2:1或更小，11.4%研究對象比值大於2.5:1。所有原發性顱內高壓患者此比值均大於或等於2.5:1。
結論：視神經鞘與視神經直徑比值在診斷原發性顱內高壓方面有應用價值。該值大於或等於2.5:1與 的顱內壓增高程度具有較高的相關性。