Alyassin A M, Lancaster J L, Downs J H, Fox P T
Department of Radiology, University of Texas Health Science Center at San Antonio 78284-6240.
Med Phys. 1994 Jun;21(6):741-52. doi: 10.1118/1.597333.
The maximum unit normal component (MUNC) method used for surface area measurement and the divergence theorem algorithm (DTA) used for volume measurement were evaluated. The accuracy and precision of these methods were investigated at varying signal-to-noise ratios (SNRs), sampling, spatial averaging, and orientation. The accuracy of the MUNC measured surface area, as indicated by the mean error, was 2.0% for seven spherical samples, with SNRs ranging from 5:1 to 39:1. The precision, as indicated by the percent coefficient of variation (% CV) for these samples, was less than 3.0%. Likewise, the accuracy and precision of the DTA measured volume for these samples were both less than 1.0%. MUNC surface area measurement from 23 samples of a computed tomography (CT) image of a wooden sphere (51.44-mm diameter) with x,y voxel size ranging from 1 to 10 mm and z voxel size ranging from 2 to 14 mm yielded an accuracy of 1.3% and a precision of 2.2%. The DTA volume measurements from 18 samples of the wooden sphere with x,y vowel size ranging from 1 to 8 mm and z size ranging from 2 to 14 mm provided an accuracy of 1.2% and a precision of 1.8%. Measurement of surface area for a cylindrical rod scanned by CT in five different orientations, ranging from along each axis to between all three axes, yielded an accuracy of 3.7% and a precision of 2.0%. The volume of the cylindrical rod measured by the DTA method for these orientations produced an accuracy of 4.0% and a precision of 3.7%. The volume measured by DTA compared well with the volume measured by a modified voxel counting method. The MUNC surface area method was superior to counting surface voxels. The accuracy and precision for five interactive surface area and volume measurements, using paired cut planes to select subsets of a computer-generated sphere with radius 25 pixels, were both less than 1.0%.
对用于表面积测量的最大单位法向分量（MUNC）方法和用于体积测量的散度定理算法（DTA）进行了评估。在不同的信噪比（SNR）、采样、空间平均和方向条件下，研究了这些方法的准确性和精密度。七个球形样本的MUNC测量表面积的准确性（以平均误差表示）为2.0%，SNR范围为5:1至39:1。这些样本的精密度（以变异系数百分比（%CV）表示）小于3.0%。同样，这些样本的DTA测量体积的准确性和精密度均小于1.0%。对一个直径51.44毫米的木球计算机断层扫描（CT）图像的23个样本进行MUNC表面积测量，其中x、y体素大小范围为1至10毫米，z体素大小范围为2至14毫米，得到的准确性为1.3%，精密度为2.2%。对该木球的18个样本进行DTA体积测量，其中x、y体素大小范围为1至8毫米，z体素大小范围为2至14毫米，得到的准确性为1.2%，精密度为1.8%。对一根圆柱形杆进行CT扫描，在从沿每个轴到三个轴之间的五个不同方向上测量表面积，得到的准确性为3.7%，精密度为2.0%。通过DTA方法对这些方向上的圆柱形杆体积进行测量，得到的准确性为4.0%，精密度为3.7%。DTA测量的体积与通过改进的体素计数方法测量的体积相比效果良好。MUNC表面积方法优于计算表面体素。使用成对切割平面选择半径为25像素的计算机生成球体的子集进行五次交互式表面积和体积测量，其准确性和精密度均小于1.0%。
