Echo shape analysis and image size adjustment on the level of echoes: improvement of parameter-selective proton images.

Parameter-selective imaging for tissue characterization is performed at low magnetic fields (0.24-0.28 T) employing echo trains with a large number of echoes (less than or equal to 50), high-power pulses, and the projection reconstruction method. Preprocessing of the raw echoes is important for the quality of the echo images which are the bases for further evaluation and generation of parameter-selective images. Two new algorithms are implemented in the image preprocessing routine TOMIKON: Echo shape analysis and image size adjustment. Echo shape analysis allows the detection and the removal of spikes in the echo signals to avoid image artifacts. Image size adjustment is performed by expanding and contracting the time basis of the echoes resulting in a size normalization of the echo images, an indispensable condition for generating diffusion images.