The present invention pertains to methods of determining where, on the skin, a diagnostic, therapeutic, or cosmetic agent is likely to be most effectively applied (e.g., injected), and to methods for monitoring a patient after such an agent has been administered. The monitoring can produce information useful in determining whether a diagnostic, therapeutic (e.g., surgical), or cosmetic regime should be initiated, continued, continued in a modified fashion, or terminated (e.g., for a brief or prolonged period of time). The methods can be repeated periodically and use a non-invasive, in vivo form of digital image speckle correlation (DISC) to track deformation of the skin.
