Objective To determine Lho corresponding relations botween the positions of intracranial lesions and scalp surface signs by using Spiral CT and CT workstations. Methods With Lhe application of American GE CT and CT workstations( AW 4. 0 ), the data of the patients'head scan images were selected Lo reconstruct four images including three — dimensional position, horizontal position, sagittal position and coronal position. From Lhose images, tho three — dimensional coordinates figures of upper limbs of bilateral outer ears, upper front skin point of cheekbones on the lesion side( in Orbitomeatal Line, OML )and lesions demanding surgery were obtained for all 13 cases of patients who need surgical navigation. Command: WiLh Lho upper limb of outer ear on the lesion side as the origin, the upper front skin point of cheekbones on the lesion side was located in OML( x - axis ), and tho upper limb of contralateral outer ear in xoy plane,a new three -dimensional coordinaLe system was acquired by means of mathematical transformation of these three — dimensional coordinatcs figures with mathematical formula, and the new coordinates figures ( x, y, z ) were calculaLed in the new three — dimensional coordinate rnsystem, with " x:" on behalf of the longitudinal distance from the target to the upper limb of outer ear on the lesion side, " zx" on behalf of the vertical distance from the target to the upper limb of outer ear on the lesion side, "vj" on behalf of vertical depth of target. This method was applied in all 13 patients to verify the navigating accuracy of the method. Results All lesions of the patients were accurately navigated. Conclusion By using Spiral CT and CT workstation, the original three - dimensional coordinates figures of skull surface signs and intracranial targets were obtained, and a new three - dimensional coordinate system was established within which the origin was the upper limb of outer ear on the lesion side and the x - axis was the OML. A new three - dimensional coordinates figures of the target was acquired to locate the surface projection of intracranial lesions with the application of mathematical methods of coordinate transformation. This method is a novel, reliable, simple and practical way to locate the intracranial lesions.%目的 利用螺旋CT图像及其后处理工作站,结合颅外标志,寻找颅内病灶与头皮各点的对应位置关系.方法 使用美国GE公司的CT及后处理工作站(AW4.0),选择患者头颅CT扫描数据,进行三维立体、水平位、矢状位和冠状位等4种图像重建,从中获得双侧外耳门上缘、病灶侧颧弓上前缘皮肤点、手术靶点的原始三维坐标值.设病灶侧外耳门上缘为原点,颧弓上前缘皮肤点位于x轴,对侧的外耳门上缘位于xoy平面上,将原始坐标数据代入坐标转换数学公式,求出上述4个点在新坐标系的新三维坐标值x1,y1,z1,即x1值为靶点距原点外耳门上缘前(后)的距离,z1值代表靶点距原点外耳门上缘上(下)的距离,y1值代表靶点垂直深度距离.该法用于13例需手术定位患者,验证其准确性.结果 所有患者均能成功定位靶点.结论 利用螺旋CT和CT工作站,获得颅外体表标志以及颅内靶点的原始三维坐标值,建立以病灶侧外耳门上缘为原点,眶耳线为x轴的新三维坐标系,通过数学方法转化,获得靶点在新坐标系下的坐标值,实现对颅内靶点的体表定位.该方法实用可靠,是一种新的简易颅内病灶定位方法.
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