Stereology (from Greek stereos = solid) was originally defined as `the spatial interpretation of sections’. It is an interdisciplinary field that is largely concerned with the three-dimensional interpretation of planar sections of materials or tissues. It provides practical techniques for extracting quantitative information about a three-dimensional material from measurements made on two-dimensional planar sections of the material. See the Examples below. Stereology is an important and efficient tool in many applications of microscopy (such as petrography, materials science, and biosciences including histology, bone and neuroanatomy). Stereology is a developing science with many important innovations being developed mainly in Europe. New innovations such as the proportionator continue to make important improvements in the efficiency of stereological procedures.
In addition to two-dimensional plane sections, stereology also applies to three-dimensional slabs (e.g. 3D microscope images), one-dimensional probes (e.g. needle biopsy), projected images, and other kinds of `sampling’. It is especially useful when the sample has a lower spatial dimension than the original material. Hence, stereology is often defined as the science of estimating higher dimensional information from lower dimensional samples.
Stereology is based on fundamental principles of geometry (e.g. Cavalieri’s principle) and statistics (mainly survey sampling inference). It is a completely different approach from computed tomography.
Classical applications of stereology include:
* calculating the volume fraction of quartz in a rock by measuring the area fraction of quartz on a typical polished plane section of rock (« Delesse principle »);
* calculating the surface area of pores per unit volume in a ceramic, by measuring the length of profiles of pore boundary per unit area on a typical plane section of the ceramic (multiplied by 4 / π);
* calculating the total length of ca
Stereology is not tomography
Stereology is a completely different enterprise from computed tomography or for DOT. A computed tomography algorithm effectively reconstructs the complete internal three-dimensional geometry of an object, given a complete set of all plane sections through it (or equivalent X-ray data). On the contrary, stereological techniques require only a few `representative’ plane sections, and statistically extrapolate from them to the three-dimensional material.
Stereology exploits the fact that some 3-D quantities can be determined without 3-D reconstruction: for example, the 3-D volume of any object can be determined from the 2-D areas of its plane sections, without reconstructing the object. (This means that stereology only works for certain quantities like volume, and not for other quantities).