Bioactive glass has high potential for bone regeneration due to its ability to bond to bone and stimulate osteogenesis whilst dissolving in the body. Although three-dimensional (3-D) bioactive glass scaffolds with favorable pore networks can be made from the sol-gel process, compositional and structural evolutions in their porous structures during degradation in vivo, or in vitro, have not been quantified. In this study, bioactive glass scaffolds were put in a simulated body fluid flow environment through a perfusion bioreactor. X-ray microtomography (mu CT) was used to non-destructively image the scaffolds at different degradation stages. A new 3-D image processing methodology was developed to quantify the scaffold's pore size, interconnect size and connectivity from mu CT images. The accurate measurement of individual interconnect size was made possible by a principal component analysis-based algorithm. During 28 days of dissolution, the modal interconnect size in the scaffold was reduced from 254 to 206 mu m due to the deposition of mineral phases. However, the pore size remained unchanged, with a mode of 682 mu M. The data presented are important for making bioactive glass scaffolds into clinical products. The technique described for imaging and quantifying scaffold pore structures as a function of degradation time is applicable to most scaffold systems. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.