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Introduction: An increasing number of multimodal images represent a valuable increase in available image information, but at the same time it complicates the extraction of diagnostic information across the images. Multispectral analysis (MSA) has the potential to simplify this problem substantially as unlimited number of images can be combined, and tissue properties across the images can be extracted automatically., Materials and Methods: We have developed a software solution for MSA containing two algorithms for unsupervised classification, an EM-algorithm finding multinormal class descriptions and the k-means clustering algorithm, and two for supervised classification, a Bayesian classifier using multinormal class descriptions and a kNN-algorithm. The software has an efficient user interface for the creation and manipulation of class descriptions, and it has proper tools for displaying the results., Results: The software has been tested on different sets of images. One application is to segment cross-sectional images of brain tissue (T1- and T2-weighted MR images) into its main normal tissues and brain tumors. Another interesting set of images are the perfusion maps and diffusion maps, derived images from raw MR images. The software returns segmentations that seem to be sensible., Discussion: The MSA software appears to be a valuable tool for image analysis with multimodal images at hand. It readily gives a segmentation of image volumes that visually seems to be sensible. However, to really learn how to use MSA, it will be necessary to gain more insight into what tissues the different segments contain, and the upcoming work will therefore be focused on examining the tissues through for example histological sections.

Monte Carlo simulations of a time-of-flight Positron Emission Tomography front end readout system (TOF-PET) are performed to investigate obtainable timing resolution at different ADC sample times using LYSO scintillators. Results from simulations with different combinations of ADC sample times and analog filter time constants are presented. To determine the coincidence resolving time (CRT), a trigger system based on a digital constant fraction zero crossing discriminator (CFD) is investigated. Such a trigger system would be suitable for running real time in a field-programmable gate array (FPGA). It is seen that below a certain sample time, the time resolution is limited by the scintillator and MPPC combination, and not the readout system. [ABSTRACT FROM PUBLISHER]