Improving stereological estimates for the volume of structures identified in three-dimensional arrays of spatial data

Investigators frequently measure the volumes of anatomic structures. These volumes can answer important scientific questions such as whether a structure differs between two groups, which structures a disease affects, or how the size of a structure relates to its function. Magnetic resonance (MR) imaging, X-ray computed tomography and confocal microscopy are used more and more frequently in anatomic studies; each yields information that is spatially organized as a three-dimensional array. We describe how to improve an efficient stereological technique for estimating the volumes of structures that are identifiable in these arrays. As an example, we apply the technique to measuring brain volumes by MR imaging. We then show how the results of the technique may be used for solving a typical problem in experimental design. This technique is applicable to a wide range of experimental problems. We discuss its limitations and offer some suggestions and observations relating to its use.