MRI inter-slice reconstruction using super-resolution.

MRI reconstruction using super-resolution is presented and shown to improve spatial resolution in cases when spatially-selective RF pulses are used for localization. In 2-D multislice MRI, the resolution in the slice direction is often lower than the in-plane resolution. For certain diagnostic imaging applications, isotropic resolution is necessary but true 3-D acquisition methods are not practical. In this case, if the imaging volume is acquired two or more times, with small spatial shifts between acquisitions, combination of the data sets using an iterative super-resolution algorithm gives improved resolution and better edge definition in the slice-select direction. Resolution augmentation in MRI is important for visualization and early diagnosis. The method also improves the signal-to-noise efficiency of the data acquisition.

A computer-based method for the assessment of body-image distortions in anorexia-nervosa patients.

A computer-based method for the assessment of body-image distortions in anorexia nervosa and other eating-disorder patients is presented in this paper. At the core of the method is a realistic pictorial simulation of lifelike weight changes, applied to a real source image of the patient. The patients, using a graphical user interface, adjust their body shapes until they meet their self-perceived appearance. Measuring the extent of virtual fattening or slimming of a body with respect to its real shape and size allows direct quantitative evaluation of the cognitive distortion in body image. In a preliminary experiment involving 33 anorexia-nervosa patients, 70% of the subjects chose an image with simulated visual weight gain between 8%-16% as their "real" body image, while only one of them recognized the original body image. In a second experiment involving 30 healthy participants, the quality of the weight modified images was evaluated by pairwise selection trials. Over a weight change range from -16% to +28%, in about 30% of the trials, artificially modified images were mistakenly taken as "original" images, thus demonstrating the quality of the artificial images. The method presented is currently in a clinical validation phase, toward application in the research, diagnosis, evaluation, and treatment of eating disorders.

Polarization and statistical analysis of scenes containing a semireflector.

We present an approach to recover scenes deteriorated by reflections off a semireflecting medium (e.g., a glass window). The method, based on imaging through a polarizer at two or more orientations, separates the reflected and transmitted scenes and determines which is which. We analyze the polarization effects, taking into account internal reflections within the medium. The scene reconstruction requires the estimation of the orientation (inclination and tilt angles) of the transparent (invisible) surface. The inclination angle is estimated by seeking the value that leads to the minimal mutual information of the estimated scenes. The limitations and the consequences of noise and angle error are discussed, including a fundamental ambiguity in the determination of the plane of incidence. Experimental results demonstrate the success of angle estimation and consequent scene separation and labeling.

Vision through semireflecting media: polarization analysis.

We present an approach to recovering scenes deteriorated by reflections off a semi-reflecting medium. The approach is based on imaging through a polarizer at two different orientations. We analyze the image-formation process, taking into account changes in reflection and polarization properties owing to internal reflections within the medium. Reconstruction by inverting this process requires estimation of the incidence angle (the inclination of the transparent medium). We estimate this angle by seeking the value that leads to decorrelation of the estimated scenes that are automatically and uniquely labeled reflected-transmitted.

The description of rat drug-induced behavior: kinematics versus response categories.

The study of rat drug-induced locomotor behavior is largely based on the assumption that behavior consists of a sequence of response categories performed by the whole animal one at a time. By analysing this behavior under (+)-amphetamine (5 mg/kg), we illustrate how even a precise definition of such categories may not be sufficient for the establishment of behavioral variables that have a "physiological reality." We describe the changes of relation between the parts of the rat's body in reference to selected coordinate systems, and show that a great variety of locomotor patterns observed under amphetamine can be reduced to as few as 3 descriptive component-variables. These continuous and relatively independent variables, which behave predictably in the course of drug action, operate simultaneously. Variations in their relative timing of onset and termination account for the apparent variability in observed behavior. The economy and generality of a description based on these variables suggest the existence of corresponding central mechanisms of control.