The concept of model-based imaging provides a possibility of integration of both structural and functional information obtained by imaging and nonimaging sources of diagnostically relevant information. Merging information of different origin and nature in a simulated computer patient-specific three-dimensional (3-D) model is important for multimodal imaging approaches to medical diagnostics. The work of F. L. Lizzi on life-like imaging done nearly 20 years ago was the first successful attempt of patient-specific 3-D computer modeling using conventional ultrasonography data. He demonstrated the applications of such 3-D models, which incorporated acoustic, optical and thermal properties of imaged tissue, in physiologic studies, in planning and monitoring ultrasonic hyperthermia and ablation. However, numerous obstacles hinder the wide use of the model-based imaging concept. Using the example of model-based imaging of prostate, the advantages and limitation on the applicability of the concept are discussed. Attempts of implementing the model-based imaging concept in the mechanical imaging technology--imaging with the use of measurements of stress pattern on the surface of tissue--are described. It is shown that composing a patient-specific 3-D model requires well-defined and carefully validated algorithms for translating features of the object assessed by an imaging modality into the quantitative anatomic and histopathologic parameters.