A new imaging method, microwave-induced thermal imaging (MITI), was developed to differentiate tissue based on thermal and dielectric properties. Image contrast depends on temporal strain in tissue, which was determined by one-dimensional speckle tracking using a phase-sensitive, correlation-based technique. The underlying mechanisms were analyzed and experimental results on biologic tissue agreed well with theoretical predictions. Because of its strong contrast between water-bearing and lipid-bearing tissue, the technique may enhance existing intravascular ultrasound (IVUS) imaging systems to identify vulnerable arterial plaque.