Glaucoma risk assessment using a non-linear multivariable regression method.

The present research investigates the relationship between the central corneal thickness (CCT), Heidelberg Retina Tomograph II (HRTII) structural measurements and intraocular pressure (IOP) using an innovative non-linear multivariable regression method in order to define the risk factors in future glaucoma development and patient management. The method is implemented to data from ninety-three open angle glaucoma eyes. The results show that in established glaucoma, CCT is significantly associated with HRTII structural measurements (maximum contour depression, cup volume inferotemporally) and IOP. They are also compared to those obtained from the application of standard linear regression methods, improving the coefficient determination R(2) by 35%, exhibiting thus the performance of the proposed methodology.

The inverse problem of a passive multiband microwave intracranial imaging method.

A novel Microwave Radiometry Imaging System (MiRaIS) has been developed and experimentally tested for feasible brain activation "remote" imaging via contactless measurements. The technique implemented, is focused microwave radiometry with the use of an ellipsoidal conductive wall cavity for focusing and a sensitive radiometric receiver for the detection of the brain conductivity and temperature variation. All system attributes in terms of spatial resolution and detection depth have been theoretically calculated. Phantom experimentation as well as human tests using single frequency receivers, have shown promising outcome concerning the potential clinical value of the proposed system, which seems to be able to pick-up brain activation, possibly caused by cortex conductivity changes. Following this research, a four-frequency radiometric receiver with a broadband antenna operating within the range 1.3-3.1GHz has been recently developed. In the present paper, a method for retrieving the conductivity variation profile detected in the above mentioned frequencies is discussed. The inverse problem solution is in detail addressed and indicative measurements are used for the validation of the solution in question. The latter represents the estimation of the conductivity variation of cortical areas, corresponding to the detection depth and spatial resolution predicted by the forward problem solution.

Experimental study of 3D contactless conductivity detection using microwave radiometry: a possible method for investigation of brain conductivity fluctuations.

The capability of detecting electrical conductivity variations using focused microwave radiometry, a method used in clinical applications for temperature distribution imaging of subcutaneous tissues, is discussed in the present study. A novel microwave radiometric system operating at 3.5 GHz, including an ellipsoidal conductive wall cavity, which provides the required beamforming and focusing, is developed. The system is capable of providing distribution measurements of the product of conductivity and temperature of any object being at a temperature above the absolute zero. The implemented experimental procedure is based on the results of an electromagnetic numerical analysis using a semianalytical method which was developed in order to compute the focusing properties of the ellipsoidal reflector. Each measurement is realized by placing the region of interest in the area of the first focus of the cavity and collecting the radiation converged at the second by an almost isotropic dipole antenna connected to a sensitive radiometer. Experimental data from cylindrical shaped saline or de-ionized water filled tank phantoms in which saline solutions of different concentrations were infused, provide promising results concerning the system's ability of detecting conductivity variations. Future research is needed in order to elucidate the potential of the proposed methodology to be used for brain conductivity measurements.