Biomedical subjects
Publications and source records attributed to J A Rafael.
In this paper some basic concepts of Digital Image processing are presented, such as image enhancement and segmentation, and some of the activities in Medical Imaging of the Image Processing group of the University of Aveiro/INESC are described.
A new method of ventilation and perfusion display onto a single image is presented. From the data on regions of interest of the lungs, three-dimensional histograms are created, containing as parameters X and Y for the position of the pixels, Z for the perfusion and colour for local ventilation. The perfusion value is supplied by sets of curves having Z proportional to the local perfusion count rate. Ventilation modulates colour. Four perspective views of the histogram are simultaneously displayed to allow visualization of the entire organ. Information about the normal ranges for both ventilation and perfusion is also provided in the histograms.
A method for the study of the dynamics of the perfusion of the compliant vascular tree of the lungs using in vivo labelled 99mTc red cells and ECG gating is presented. Following blood pool labelling, posterior, ECG gated gamma camera images were acquired in time intervals of about 40 ms for 1,000-2,000 cardiac cycles. The images show the lungs plus the heart and great vessels. The image sequence containing the periodic variation of the blood activity in the lungs during the cardiac cycle is analyzed to obtain volume curves and functional images of the amplitude and phase of the lung perfusion. The interference of the heart and great vessels with the left lung can be avoided by excluding the superimposed areas in the ROIs with the sacrifice of part of the left lung. This technique allows dynamic visualization of the perfusion process in the compliant arterial and venous vascular trees of the lungs. The results obtained with this method in normals and some pathologies are discussed.