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G Zavattini

Publications and source records attributed to G Zavattini.

23 records · Page 2Linked to original sources
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Quality of life in chronic diseases of the aged: the importance of cognitive deterioration.

The interference of a chronic disease on the aging process reduces patients efficiency in confronting everyday life events and their Quality of Life (QOL). The purpose of this study was to examine the interaction between cognitive problems and emotional difficulties as related to several chronic diseases commonly present among aged patients in contributing to their QOL reduction. Diseases considered were: chronic cerebro-vascular disorders non-insulin dependent diabetes mellitus and hypertension. Memory characteristics and subjective evaluation of several areas of daily living where problems could be present were assessed. Severity of cognitive and behavioral deterioration emerged as a major component independent from type of disease, contributing to reduction of QOL. Disease type determined the different risk of presence of an objective reduction of memory efficiency. The QOL of aged patients was identified as a multidimensional array of different components among which cognitive deterioration assumes a primary role. These results, together with analogous findings from previous studies, underline the importance of considering cognitive efficiency in aged patients even with chronic diseases not directly affecting CNS in order to evaluate their needs.

Journal Article↗
PubMedDate not supplied

Use of a fast EM algorithm for 3D image reconstruction with the YAP-PET tomograph.

OBJECTIVE: We would like to improve the image reconstructions for both signal-to-noise ratio (SNR) and spatial resolution characteristics for the small animal positron emission tomograph YAP-PET, built at the Department of Physics of Ferrara University. The three-dimensional (3D) filtered backprojection (FBP) algorithm, usually used for image reconstruction, has a limited angle restriction due to the tomograph geometry, which causes a serious loss in sensitivity. METHODS: We implemented a 3D iterative reconstruction program using the symmetry and sparse properties of the 'probability matrix', which correlates the emission from each voxel to the detector within a coincidence tube. A fraction only of matrix elements are calculated before the reconstruction and stored on disk: this allows us to avoid on-line computation. A depth dependent function differentiates the voxels in a coincidence tube. Three experimental phantoms with no background were reconstructed by using the program, in comparison with traditionally used FBP. RESULTS: The adopted method allowed us to reduce the computation time significantly. Furthermore, the simple depth dependent function improved the spatial resolution. With 64 x 64 x 20 voxels of 0.625 x 0.625 x 2.0 mm(3) in the field of view, the computation time was less than 4 min per iteration on a Sparc Ultra 450 Workstation, and less than 6 min per iteration on a Mac-PPC G3 300 MHz: the spatial resolution measured with a 0.8 mm diameter 18F-FDG filled capillary reconstructed in this way was 2.0 mm FWHM. By decreasing the voxel size to 0.3125 x 0.3125 x 2.0 mm(3) per voxel the transaxial FWHM was 1.7 mm with a computation time of 15 min per iteration on a Sparc Ultra 450. By using all the acquired data, the SNR improves from 1.3 to 6.0 in the worst measured case, a pair of 0.8mm diameter 18F-FDG filled capillaries, which are 2.5 mm apart each other. CONCLUSION: The adoption of iterative reconstruction allowed us to overcome the loss in sensitivity of previously used FBP: this improved the SNR. The studies of symmetry and sparse properties avoided a severe increase of the reconstruction time and of storing space on disk. This fast EM Algorithm is now routinely used for the image reconstruction with the YAP-PET tomograph.

Algorithms↗