1. A method for detection of structure in ultrasound M-mode imaging, the method comprising: acquiring M-mode data representing a line within a patient over a range of time; identifying a first portion of the line as associated with a first anatomical structure of a heart of the patient as a rough estimate, the first portion comprising a first plurality of depths, the identifying being a function of the M-mode data; identifying constrained by the rough estimate a first location of the first anatomical structure within the first portion, a search for the identifying of the first location being limited to the first portion; and displaying information associated with the first location.