Ultrasound-induced blood stasis was demonstrated thirty years ago. Most of the literature has been focused on methods employed to prevent stasis from occurring during ultrasound imaging. The current work discusses some of the theory behind this phenomenon. It also demonstrates ultrasound-induced blood stasis in murine tumor and muscle tissue, observed through noninvasive measurements of optical spectroscopy, and discusses possible diagnostic uses. We demonstrate that, using optical spectroscopy, effects of ultrasound can be used to noninvasively differentiate tumor from muscle tissue in mice, and that we can quantitatively differentiate tumor from muscle with maximum specificity 0.83, maximum sensitivity 0.79, and area under ROC curve 0.90, using a simple algorithm.