This paper presents a computational methodology for integrating techniques from protein image interpretation and protein sequence threading, applied to the problem of structure determination from experimental X-ray crystallographic electron density maps. In the proposed architecture, image interpretation of an electron density map produces candidate structural segments; threading is applied to evaluate these hypothesized segments and thus to constrain the set of possible image interpretations. We present the results of experiments designed to test ability of the threading module to discriminate between correct and incorrect alignments of protein sequences onto structural models derived from protein image interpretation. The long-term goal of this research is to improve our ability to determine protein structures from crystallographic data, and to further our understanding of the underlying relationship between sequence and structure.