Optical Imaging - Correction Techniques in Emission Tomography - page 271

(a)StandardEM,TransversalView (b)4DEM,TransversalView
(c)StandardEM,CoronalView (d)4DEM,CoronalView
(e)StandardEM,SagittalView (f)4DEM,SagittalView
FIGURE9.2: Two exemplary H 2 15 O reconstructions, acquired with the stan-
dalone Siemens PET Scanner ECAT EXACT (model 921). It should be no-
ticed that with this type of scanner image acquisition can be done only slice-
by-slice. The images on the left-hand side show standard EM reconstructions
of a slice of the seventh frame in transversal, coronal and sagittal view. The re-
constructions have been smoothed by additional Gauss filtering between each
EM iteration. The images on the right-hand side show the same views of the
same slice but computed via the described 4D-EM reconstruction method.
Again, after each EM iteration Gauss filtering has been applied to ensure
spatial smoothness. The images on the right-hand side have a much higher
signal-to-noise ratio than those derived from the frame-independent standard
EM reconstructions.