Figure 8.

(taken from the Oxford Handbook of CMR, OUP) Mechanism for potential underestimation of aortic regurgitation. The gap between the valve and the image plane for flow mapping expands in systole from a combination of movement of the aortic valve towards the apex and elastic expansion of the aortic sinuses and root. Blood entering this space in systole (grey stippled area) returns to the LV in diastole (via a regurgitant valve) without passing through the image plane (dashed lines), and thus may not be measured.