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D Farina

Publications and source records attributed to D Farina.

80 records · Page 5Linked to original sources
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Compensation of the effect of sub-cutaneous tissue layers on surface EMG: a simulation study.

A mathematical model of a four-layer medium (muscle+fat+skin+air) is investigated. The system is studied in cartesian coordinates with the hypotheses of muscle anisotropy and isotropy of the fat and skin layers, assuming the fat to be less conductive than the skin. Determination of the potential distribution over the skin, due to sources in the muscle, is based on the solution of the Poisson equation in the spatial frequency domain in the different media. The arbitrary constants are determined imposing the boundary conditions. In this way the transfer function of the fat and skin layers is found and can be used to compute the potential distribution of the muscle-fat interface. The physiological parameters were obtained from literature. The results of simulation studies are proposed; it is clear that the subcutaneous tissue layers produce an attenuation and widening of the potential distribution present at the muscle surface. These effects can be partially compensated using high-pass spatial filters as proposed in the literature. A new class of bidimensional spatial filters is proposed; the filters are defined on the basis of the information about the isotropic layers rather than being general filters. An approximation of the ideal inverse transfer function of the sub-cutaneous layers is proposed as a discrete spatial filter that can be implemented with matrices with a small number of electrodes (maximum of 25 electrodes) and practicable interelectrode distance. A simulated evaluation of the new filter and the limitations of the approach are presented.

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[Multislice TC in the planning of abdominal aortic aneurysms].

PURPOSE: To assess the effectiveness of routine MSCT in the planning of endovascular and open surgery of AAA. PATIENTS AND METHODS: A series of 42 consecutive patients was prospectively examined by MSCT (Siemens Sensation 16, arterial phase, bolus tracking threshold=200 HU, 75 mm collimation) for AAA surgery planning. MPR, MIP and VRT reconstructions were routinely obtained. In four cases previous DSA was available for comparison. RESULTS: AAA was classified infrarenal (28/42), juxtarenal (10/42), pararenal (2/42) and thoraco-abdominal (Crawford type IV (2/42). In 27/42 AAA maximum diameter was greater than 45 mm; involvement of a single iliac artery (6/42) or both (7/42) was also observed. Vascular anomalies were detected in 54.8% of patients. Overall, 22 accessory renal arteries, 4 visceral aneurysms (2 renal arteries, 1 celiac trunk, 1 SMA) and 1 retroaortic renal vein were detected. Patency of IMA was demonstrated in 25/42 AAA. Based on MSCT data 11 patients were treated (7 by open surgery, 4 by endovascular approach). No discrepancy was observed concerning the planned infrarenal clamping, all accessory renal arteries were identified at surgery. In all AAA, endovascular treatment planning matched the actual geometry of vessels. CONCLUSIONS: Although this series is limited, information provided by axial images, MPR, MIP and VRT reconstructions fulfilled all requirements for routine planning of both open and endovascular treatment of AAA. Moreover, VRT reconstructions enable a more precise assessment of accessory renal arteries origin and course and spatial orientation of AAA neck.

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