1. A method for identifying a structure of interest within image data, comprising: receiving image data; receiving an initial point within the received image data; transforming the received image data into a scale-space; performing geometric fitting using prior-constrained mean shift on the scale-space image data to identify a structure candidate in a vicinity of the initial point; using the identified structure candidate to set up a prior constraint for subsequent iterations; presenting the identified structure candidate to a user and querying the user to determine whether the identified structure candidate is a structure of interest; and when the identified structure candidate is determined to not be a structure of interest, repeating the steps of performing geometric fitting using prior-constrained mean shift and presenting an identified structure candidate until it is determined that an identified structure candidate is a structure of interest, wherein the above steps are performed by a computer system.