—In this paper, we present an advanced image processing sequence to perform nondestructive inspection from 3-D terahertz (THz) images. We develop all the steps starting from a 3-D tomographic reconstruction of a sample from radiographs acquired with a monochromatic millimeter-wave imaging system to an automated segmentation, extracting the different volumes of interest (VOI) composing the sample. This leads to 3-D visualiza-tion and dimensional measurements. This inspection is completed by a skeletonization and caliber analysis providing an accurate assessment of the structure, geometry, and morphology of the acquired object. Overall sequence is implemented onto an unique software and validated through different sample analysis.