1. A method of analyzing image data comprising a 3-dimensional representation of a brain collected with an imaging device, the method comprising: with at least one processor: obtaining an indication of a position of a first anatomical landmark in a 3-dimensional representation of a brain collected during a first imaging session and an indication of a position of a second anatomical landmark in the 3-dimensional representation of the brain collected during the first imaging session; and computing, from the 3-dimensional representation of the brain collected during the first imaging session, a first slice with an orientation in the 3-dimensions, wherein the orientation of the first slice is selected based on the obtained position of the first anatomical landmark and the obtained position of the second anatomical landmark such that the orientation of the first slice is not constrained by an orientation of the imaging device and the first slice encompasses: a position selected based on at least the position of the first anatomical landmark and a position selected based on at least the position of the second anatomical landmark; obtaining an indication of a position of the first anatomical landmark in a 3-dimensional representation of a brain collected during a second imaging session and an indication of a position of a second anatomical landmark in the 3-dimensional representation of the brain collected during the second imaging session; computing, from the 3-dimensional representation of the brain collected during the second imaging session, a second slice with an orientation in the 3-dimensions, wherein the orientation of the second slice is selected based on the obtained position of the first anatomical landmark and the obtained position of the second anatomical landmark such that the orientation of the second slice is not constrained by an orientation of the imaging device, wherein the orientation of the second slice with respect to the orientation of the imaging device is different than the orientation of the first slice with respect to the orientation of the imaging device, and wherein the second slice encompasses: a position selected based on at least the position of the first anatomical landmark and a position selected based on at least the position of the second anatomical landmark; and measuring a change in a characteristic of an anatomical feature based on a comparison of information from the first slice to information from the second slice to track the change in the characteristic of the anatomical feature over time.