Page 6 - The Diastolic Shell - part 1
This is a short axis MRI of a normal left ventricle. In the diastolic frame on the left, the myocardium has been tinted blue and the cavity pink.
In the systolic frame on the right, the outline of the diastolic epicardial position has been added. This is quite easy to do with basic image processing software, as in the normal the axes of the heart hardly move at all during the cardiac cycle and the outline just has to be superimposed on the systolic frame keeping the margins co-incident. You will see that the epicardium has moved inwards in all areas, as it must. The gap between the systolic epicardial border and its diastolic "shell" has been tinted with green.
These images show how the myocardium seems to thicken a lot despite relatively little movement in the epicardial outline, seemingly adding to the conundrum of cell versus wall thickening that we met on page 1. The explanation begins to become clear when the same is done to the images of the long axis, in the next page.