Hierarchical Cluster Analysis to Aid Diagnostic Image Data Visualization of MS and Other Medical Imaging Modalities.

Perceiving abnormal regions in the images of different medical modalities plays a crucial role in diagnosis and subsequent treatment planning. In medical images to visually perceive abnormalities' extent and boundaries requires substantial experience. Consequently, manually drawn region of interest (ROI) to outline boundaries of abnormalities suffers from limitations of human perception leading to inter-observer variability. As an alternative to human drawn ROI, it is proposed the use of a computer-based segmentation algorithm to segment digital medical image data.Hierarchical Clustering-based Segmentation (HCS) process is a generic unsupervised segmentation process that can be used to segment dissimilar regions in digital images. HCS process generates a hierarchy of segmented images by partitioning an image into its constituent regions at hierarchical levels of allowable dissimilarity between its different regions. The hierarchy represents the continuous merging of similar, spatially adjacent, and/or disjoint regions as the allowable threshold value of dissimilarity between regions, for merging, is gradually increased.This chapter discusses in detail first the implementation of the HCS process, second the implementation details of how the HCS process is used for the presentation of multi-modal imaging data (MALDI and MRI) of a biological sample, third the implementation details of how the process is used as a perception aid for X-ray mammogram readers, and finally the implementation details of how it is used as an interpretation aid for the interpretation of Multi-parametric Magnetic Resonance Imaging (mpMRI) of the Prostate.

Identification and characterization of somatosensory off responses.

Event-related potentials (ERPs) have been recorded in response to the offset of sensory stimulation in both the auditory and visual modalities. The present experiment employed vibratory stimulation to characterize somatosensory ERPs in response to different duration stimuli. In two separate experiments, we recorded attended and unattended somatosensory ERPs to 70 Hz, sine wave stimuli using the following durations: 20 ms, 50 ms, 70 ms, 150 ms, 170 ms, 250 ms and 1000 ms. An oscillating coil delivered stimuli through a 'T-bar' to digits 2 and 3 of the right hand. The amplitude and latency measurements of P50, P100 and a later negative component (No1) were analyzed using MANOVA. There was no significant difference in the latency values of the P50 and P100, but as the duration increased, there was a significant increase (P < 0.01) in the latency of No1. No1 appeared 130 ms +/- 9 ms following the offset of the stimulus. Amplitude values of the P50 and P100 components decreased as the stimulus duration increased and this effect became significant (P < 0.05) as the duration difference increased. Stimuli of 150 ms or greater evoked a negative baseline shift that persisted for the duration of the stimulus and area measurements in 7 out of the 10 subjects showed a significant increase in amplitude when the stimulus was attended. An intracranial case study supported these findings. The characteristics of the No1 component indicate it is a somatosensory off response, and it, in conjunction with the P50 and sustained potential, may reflect activity of a neural system that is responsive to changes in the tactile environment.