Figure 5c. HARP image analysis. The HARP technique enables measurement of motion from a series of tagged MR images (such as that in a) by filtering selected peaks in the k-space representation of the image (circle in b). The resulting image can be decomposed into a harmonic magnitude image (c) or a HARP image (d). The magnitude image shows anatomic detail and can be used for segmentation. In contrast, the HARP image contains myocardial motion information. Because the value of a material point on a HARP image is invariant over time, this technique can be used to track the trajectory of a given point or points and to compute either lagrangian or eulerian measurements of strain.