A navigation tool that provides a side-by-side display of two temporally related medical images of the same region of a patient. A plurality of lines extend between the images, at least a first line beginning at a feature at a first location in a first image and ending at a corresponding feature at a corresponding location in the second image and at least a second line extending from a feature found at a second location in one of the images toward a corresponding second location in the other image and indicating a feature found in one image but not the other. Preferably, the navigational tool also includes a scroll bar alongside the display of medical images. On the scroll bar are a series of markers, each marker corresponding to one of the plurality of lines that extend between the images and preferably being aligned with that line.