Example illustrating the comparison of segmental perfusion by CMR and microsphere techniques at rest. A single time frame of a perfusion study at 3 Tesla after occlusion of the LAD is shown at the upper left. The middle image (top row) shows the overlay with the microsphere distribution after transfer of the cryomicrotome images in the same coordinate space. Please note that this image provides a 2D representation of the overlaid 3D perfusion and microsphere volumes of interest as defined by the slice thickness of the perfusion CMR slices. There was good agreement between CMR and microsphere derived perfusion values without any clustering or clumping of the microspheres. Segmental microsphere quantification reveals the perfusion defect and the normal perfusion in remote myocardium (upper right corner). In the middle row segmentation of the perfusion image is displayed (left), as well as segmental signal intensity (SI) time curves during first pass of gadolinium (middle). Using the SI-time curves with different quantification algorithms delivers CMR based quantitative results [mL/min/g] depending on the algorithm used (lower row). In this example Fermi function deconvolution shows the closest agreement with the microspheres based results (lower left corner).