Antonio Benassi

Quantitative texture analysis in two-dimensional echocardiography : application to the diagnosis of myocardial amyloidosis.

Qualitative and subjective analysis of two-dimensional echocardiographic images of the myocardial wall allows one to identify amyloid heart disease; the quantitative analysis of regional image texture might be an accurate method to differentiate normal from amyloid myocardial structures. To test this hypothesis, two-dimensional echocardiograms of nine normal subjects and six patients with histologically documented amyloid heart disease were evaluated. Quantitative texture measurements of the first order (mean gray level, skewness, kurtosis, energy and entropy) overlapped between the two groups. Among the second order statistics variables, entropy was significantly and consistently higher in amyloid versus normal patient data (septum in parasternal long-axis view: 6.3 +/- 0.3 versus 5.9 +/- 0.4; septum in apical four chamber view: 6.2 +/- 0.2 versus 5.8 +/- 0.3). Therefore, amyloid-involved myocardial walls show ultrasound image texture alterations that may be quantified with digital image analysis techniques.

Underwater study of arterial blood pressure in breath-hold divers

Knowledge regarding arterial blood pressure (ABP) values during breath-hold diving is scanty. It derives from a few reports of measurements performed at the waters surface, showing slight or no increase in ABP, and from a single study of two simulated deep breath-hold dives in a hyperbaric chamber. Simulated dives showed an increase in ABP to values considered life threatening by standard clinical criteria. For the first time, using a novel noninvasive subaquatic sphygmomanometer, we successfully measured ABP in 10 healthy elite breath-hold divers at a depth of 10 m of freshwater (mfw). ABP was measured in dry conditions, at the surface (head-out immersion), and twice at a depth of 10 mfw. Underwater measurements of ABP were obtained in all subjects. Each measurement lasted 50-60 s and was accomplished without any complications or diver discomfort. In the 10 subjects as a whole, mean ABP values were 124/93 mmHg at the surface and 123/94 mmHg at a depth of 10 mfw. No significant statistical differences were found when blood pressure measurements at the water surface were compared with breath-hold diving conditions at a depth of 10 mfw. No systolic blood pressure values >140 mmHg or diastolic blood pressure values >115 mmHg were recorded. In conclusion, direct measurements of ABP during apnea diving showed no or only mild increases in ABP. However, our results cannot be extended over environmental conditions different from those of the present study.

Study for a portable IR sensor to detect the blood temperature during coronary bypass implantation

The objective of this research was to investigate the possibility of using an infrared prototype device for the detection of the blood temperature during a surgical operation for coronary bypass implantation. The correlation between the fluid temperature time behavior and the fluid flow rate was demonstrated. Each blood vessel acts like a thermal wave emitter, so the amount of heat is proportional to the blood flow detected by the IR sensor. The idea was to design a low cost portable device with the advantage that it can be placed near the region of interest. We chose a pyroelectric sensor for its high-quality cost ratio. Because this kind of sensor detects only a variable infrared source, we used an electromechanical chopper for modulating the radiation. It consists of an electronic shutter whose opening speed is controlled by an astable multivibrator. The output signal was analyzed using a dedicated electronic circuit including a bandpass filter and an amplifier; then an acquisition board was employed f...

3D image reconstruction using Radon transform

Computed tomography as well as magnetic resonance or positron electron tomography is currently the most commonly used medical imaging modalities for the analysis of human body complex structures and organs, where diseases must be recognized and identified. The image reconstruction process used in these tomography techniques is usually based on the Radon transform (RT). In this paper, an algorithm based on Markov chain Monte Carlo methods for reconstruction of 2D–3D structures is introduced, including correction of noise directly from the RT sinograms. The 3D reconstruction is independent by the instrumental technique and can be applied to any RT-based medical imaging technologies.

Electromagnetic method for sample-induced resistance calculation of magnetic resonance coils

Signal-to-Noise Ratio (SNR) calculation in Magnetic Resonance (MR) experiments requires the knowledge of biological sample-induced resistance value. Many authors studied sample?coil interaction by using quasi-static approach, with very simple coil and sample geometries; such method fails at high-field Magnetic Resonance Imaging (MRI). In this paper, we propose a theoretical algorithm for sample-induced resistance estimation, which uses a numerical solver based on Finite-Difference Time-Domain (FDTD) method for simulating MR systems. Comparison with experimental data demonstrated the great accuracy of the developed algorithm. The proposed method can be used as a tool to estimate sample-induced resistance values for more complex geometries.

Radiofrequency measurement of liquid sample dielectric properties for magnetic resonance applications

Specific Absorption Rate (SAR) is the dosimetric parameter currently used as a standard in the safety recommendation reports for Magnetic Resonance Imaging (MRI) procedures. In this paper, a coil-based system for liquid sample dielectric property measurements in the RF range is proposed, characterised by the non-contact between the sample and the measurement electrodes. The measurement system is described, tests of conventional liquid dielectric properties are reported and, finally, saline solution conductivity measurements used for the preparation of MR phantoms are reported and discussed.

Computerized radio-frequency analysis of concentration and 'decay' of echo-contrast agents

The linear relationship between dose of contrast agent and radio-frequency (RF) signal constitutes a means of noninvasive evaluation of intracardiac flows by contrast echocardiography. To assess the concentration of echo-contrast agents by ultrasound, a commercially available echocardiographic instrument was modified. The RF signal (unprocessed backscattered signal) corresponding to a region of interest inside the 2-D echo image was sampled in real time and transferred online to a personal computer. The relationship between different doses of contrast agent and RF signal was tested in an in vitro system of circulation. In the range of doses between 0.25 and 1.5 ml of contrast a linear correlation was found between dose and RF (r=0.92). At higher doses (1.75-2.0) ml, the dynamic converter used in this modified echo instrument produced a significant distortion of the signal. The system also made it possible to study the spontaneous decay of the echo contrast agent. The spontaneous T/sub 1/2/ (68 s) is long enough to allow flow evaluation.<<ETX>>

Computerized analysis of the transmural distribution of myocardial echo-contrast effect

The authors describe a method for the automatic analysis of the transmural distribution of the myocardial echo contrast effect. In anesthetized open-chest dogs the contrast agent SHU-454 was bolus-injected into the aortic root during short-axis 2-D echo, both at baseline and during coronary stenosis. End-diastolic echo images were digitized offline. In the first image of the sequence, the left-ventricular (LV) inner and outer myocardial edges were digitized. From the gravity center of the LV cavity a grid was automatically drawn to divide the myocardium into 16 equal sectors, and each sector into three layers. For each layer, the mean video density and the area were measured, sorted by sector and layer, and transferred online to a personal computer for further analysis. This system allows an automatic analysis of the distribution of the myocardial echo contrast effect, both in the space and in the time domain. Since the spatial distribution of the contrast effect parallels the distribution of coronary blood flow, this method might be a tool for studying the transmural distribution of coronary blood in vivo.<<ETX>>

Information systems for the management of clinical, administrative and government data of clinical imaging laboratories

From its first implementation, the integrated clinical and healthcare information system, developed at the CNR Clinical Physiology Institute, undergoes to updated and upgraded procedures and protocols, by solving problems of: harmonization of instrumentation of different brands; management of multimedial data provided by different medical imaging labs; satisfaction of both clinical and research needs as well as legal and economical requirements; user-friendship of the provided tools. Peculiar attention has been paid to the management of the laboratories devoted to biomedical imaging: medical and healthcare operators have coworked with engineers, to get a system able to guarantee coordinated activity, higher efficiency, simplified procedures, major concentration onto the medical decision-making issues, by supporting conventional techniques as well as new hybrid imaging technologies.

Quantitative Ultrasonic Imaging of the Atherosclerotic Plaque: In Vitro and Preliminary in Vivo Findings

Ultrasonic tissue characterization of atherosclerosis has been attempted in several studies in vitro1–6. Conventional ultrasound offers morphologic information, and some clue to the identification of plaque structure. However, there is greater potential in ultrasound for the characterization of plaque composition.