In Vivo Small Animal Imaging: A Comparison to Gross and Histopathologic Observations in Animal Models

Few publications have compared noninvasive in vivo imaging to either gross findings or histopathology in rodent models. Many researchers are using either in vivo imaging or histology to test their hypotheses. In vivo imaging methods are ideal for longitudinal evaluations to follow disease progression or to probe different disease processes that histopathology does not address, but in most cases, imaging has been used in investigational toxicity studies rather than routine safety assessment. Evaluation of drugs for toxicity or efficacy typically uses gross pathology as an initial morphologic screening method followed by the gold standard, histopathology. Each of these methods has its own merits and, in most cases, can complement or validate each other. This chapter will focus on examples that utilize both imaging (in vivo or ex vivo) and postmortem pathologic analysis to compare and contrast the strengths and weaknesses of each morphological method.