Amplitude remapping as a step towards standardizing the analysis of MR-images

We investigate the utility of amplitude remapping of magnetic resonance (MR)-images for making the analysis of such images more independent of the MR-device, the selected sequence, and its parameters. To this end, we analyze the morphological structure of trabecular bones using weighted scaling indices and Minkowski functionals in the context of osteoporosis. After remapping the amplitude distribution of MR-images onto a normal distribution with zero mean and unit variance, we study how the diagnostic performance of the structure measures is affected by this remapping. The diagnostic performance of the scaling index method is stable under the remapping for both spin echo (SE) and gradient echo (GE) sequences: The area under curve (AUC) value from the ROC analysis changes only slightly from 0.76 (original image) to 0.74 (remapped image) for the SE sequence and from 0.78 to 0.77 for the GE sequence. For the Minkowski functionals, the diagnostic performance suffers significantly for the SE sequence, whereas it is much more robust for the GE sequence. Therefore, the scaling index method should be the method of choice when analyzing MR-images after amplitude remapping. We also find that in the scaling index analysis, the remapping makes the results much more consistent between the SE and the GE sequence by bringing the histograms of the scaling indices closer together. Thus, the amplitude remapping can be used as a first step to standardize the scaling index analysis between different sequences of an MRI device.     «

We investigate the utility of amplitude remapping of magnetic resonance (MR)-images for making the analysis of such images more independent of the MR-device, the selected sequence, and its parameters. To this end, we analyze the morphological structure of trabecular bones using weighted scaling indices and Minkowski functionals in the context of osteoporosis. After remapping the amplitude distribution of MR-images onto a normal distribution with zero mean and unit variance, we study how the diag...     »