Figure 5a. Anisotropic and isotropic data. (a) Single–detector row CT performed with a nominal section thickness of 5 mm and a 512 x 512 matrix results in reconstructed data that are anisotropic, consisting of voxels with a facing pixel size of approximately 0.625 mm but a depth of 5 mm. This data set provides satisfactory axial images but has limited potential for secondary data reconstruction. (b) Sixteen-channel CT performed with wide collimation results in reconstructed data that are anisotropic, with a z-axis dimension (1.25 mm) approximately twice the size of the facing pixel (0.625 mm). By overlapping the reconstruction interval (which is not limited by section collimation), this data set provides excellent reformatted and volume-rendered images for many applications. (c) Sixteen-channel CT performed with narrow collimation results in reconstructed data that are isotropic, consisting of voxels that are relatively symmetric in all dimensions (0.625 mm). This data set provides exquisite data for multiplanar and 3D applications.