Romano Zannoli

A new integrated instrumental approach to autonomic nervous system assessment

BACKGROUND AND OBJECTIVESnThe autonomic nervous system (ANS) regulates involuntary body functions and is commonly evaluated by measuring reflex responses of systolic and diastolic blood pressure (BP) and heart rate (HR) to physiological and pharmacological stimuli. However, BP and HR values may not sufficient be to explain specific ANS events and other parameters like the electrocardiogram (ECG), BP waves, the respiratory rate and the electroencephalogram (EEG) are mandatory. Although ANS behaviour and its response to stimuli are well-known, their clinical evaluation is often based on individual medical training and experience. As a result, ANS laboratories have been customized, making it impossible to standardize procedures and share results with colleagues. The aim of our study was to build a powerful versatile instrument easy-to-use in clinical practice to standardize procedures and allow a cross-analysis of all the parameters of interest for ANS evaluation.nnnMETHODSnThe new ANScovery System developed by neurologists and technicians is a two-step device: (1) integrating physiological information from different already existing commercial modules, making it possible to cross-analyse, store and share data; (2) standardizing procedures by an innovative tutor monitor able to guide the patient throughout ANS testing.nnnRESULTS AND CONCLUSIONSnThe daily use of the new ANScovery System in clinical practice has proved it is a versatile easy to use instrument. Standardization of the manoeuvres and step-by-step guidance throughout the procedure avoid repetitions and allow intra and inter-patient data comparison.

Effect of intermediate ZrO2-CaO coatings deposited by cold thermal spraying on the titanium-porcelain bond in dental restorations.

STATEMENT OF PROBLEMnMetal ceramic systems are used for the majority of dental crowns and fixed dental prostheses. However, problems with porcelain bonding are encountered when titanium is used as the substrate.nnnPURPOSEnThe purpose of this study was to evaluate the effect of intermediate calcium oxide-stabilized zirconia (ZrO2-CaO) coatings deposited by cold thermal spraying on the titanium-porcelain bonding in dental restorations.nnnMATERIAL AND METHODSnTwo different types of ZrO2-CaO coatings obtained by oxyacetylene cold thermal spraying deposition were applied on commercially pure titanium bars before adding the porcelain layer. Type 1 was obtained by directly spraying the ZrO2-CaO powder on the titanium substrate. Type 2 was obtained by spraying a bond coat of nickel-aluminum-molybdenum alloy before spraying the ZrO2-CaO powder. Three-point bend tests according to International Organization of Standardization 9693-1:2012 were carried out to evaluate the debonding strength for the ZrO2-CaO-coated specimens (types 1 and 2) in comparison with a noncoated group (control), which received a traditional bonder-based adhesive technique. The results were compared with ANOVA, followed by the Student-Newman-Keuls test for pairwise comparisons. Scanning electron microscopy and energy dispersion spectroscopy were used to examine the interfacial properties and the failure mode of eachxa0group.nnnRESULTSnMean (±standard deviation) debonding strength values for type 1 coating (25.97 ±2.53 MPa) and control (23.51xa0±2.94 MPa) were near the acceptable lower limit of 25 MPa indicated by the International Organization of Standardization 9693-1:2012 and were not significantly different (Student-Newman-Keuls test, P>.05). Type 2 coating produced an improved titanium-porcelain bonding (debonding strength=39.47 ±4.12 MPa), significantly higher than both type 1 (Student-Newman-Keuls test, P<.05) and control (Student-Newman-Keuls test, P<.05). Scanning electron microscopy-energy dispersion spectroscopy analysis confirmed these findings, which revealed a predominant cohesive failure mode for typexa02.nnnCONCLUSIONSnAn intermediate coating layer of ZrO2-CaO plus a substrate of bonding nickel-aluminum-molybdenum alloyxa0applied by oxyacetylene cold thermal spraying deposition provided an improved titanium-porcelain bond.

MR Spectroscopy in Prostate Cancer: New Algorithms to Optimize Metabolite Quantification.

Prostate cancer (PCa) is the most common non-cutaneous cancer in male subjects and the second leading cause of cancer-related death in developed countries. The necessity of a non-invasive technique for the diagnosis of PCa in early stage has grown through years. Proton magnetic resonance spectroscopy (1H-MRS) and proton magnetic resonance spectroscopy imaging (1H-MRSI) are advanced magnetic resonance techniques that can mark the presence of metabolites such as citrate, choline, creatine and polyamines in a selected voxel, or in an array of voxels (in MRSI) inside prostatic tissue. Abundance or lack of these metabolites can discriminate between pathological and healthy tissue. Although the use of magnetic resonance spectroscopy (MRS) is well established in brain and liver with dedicated software for spectral analysis, quantification of metabolites in prostate can be very difficult to achieve, due to poor signal to noise ratio and strong J-coupling of the citrate. The aim of this work is to develop a software prototype for automatic quantification of citrate, choline and creatine in prostate. Its core is an original fitting routine that makes use of a fixed step gradient descent minimization algorithm (FSGD) and MRS simulations developed with the GAMMA libraries in C++. The accurate simulation of the citrate spin systems allows to predict the correct J-modulation under different NMR sequences and under different coupling parameters. The accuracy of the quantifications was tested on measurements performed on a Philips Ingenia 3T scanner using homemade phantoms. Some acquisitions in healthy volunteers have been also carried out to test the software performance in vivo.

Understanding the basic concepts of CO2 angiography

The diagnostic quality of carbon dioxide angiography depends both on optimal setting of radiological aspects (X-ray emission and image post-processing) and on the mechanical behavior of the injected gas bubbles. The gas behavior differs in large cavities (du2009>u200912u2009mm), medium sized vessels (du2009>u20096u2009mm), and small diameter vessels (du2009<u20096u2009mm): to optimize the result the operator has to adapt his action to the physical rules governing the phenomenon in the particular situation. In most cases, it is impossible to fill a vessel completely with gas, and to obtain an adequate angiogram, the gas volume and injection pressure must be properly selected, patients position must be adjusted and radiological image optimization algorithms, like Digital Subtraction Angiography (DSA) and stacking, must be applied. In this optimization process, the cultural and practical intervention of a medical physicist is fundamental. Obtaining a good quality CO2 angiogram is not only a matter of medical operator experience or radiologica...

CARBON DIOXIDE ANGIOGRAPHY: SIMULATION OF OPERATIVE CONDITIONS FOR DIAGNOSTIC IMAGE OPTIMIZATION

Carbon dioxide angiography is based on the visualization (i.e., the radiographic contrast) of gas bubbles injected in blood vessels. By using an experimental X-ray bench, the energy response of a flat panel detector has been measured (Varian CB4030) and, with a dedicated phantom and a software simulation, the image contrast of vessels is injected with Iodine and CO2. Moreover, the dynamical behavior of a moving gas bubble has been studied with the software simulator. The results show that the contrast generated by carbon dioxide is about one fourth of that obtained with iodine, demonstrating that CO2 angiography should use different radiological settings with respect to iodine angiography. In particular, a kVp increase has a lower reduction of contrast-to-noise-ratio (CNR) with carbon dioxide than with iodinated contrast medium (CM), suggesting possible technological improvements both on radiological emission and image enhancement methods.

Carbon dioxide coronary angiography: A mechanical feasibility study with a cardiovascular simulator

The aim of this study was to carry out a bench evaluation of the biomechanical feasibility of carbon dioxide (CO2) coronary arteriography. Many patients among the aging population of individuals requiring cardiac intervention have underlying renal insufficiency making them susceptible to contrast-induced nephropathy. To include those patients, it is imperative to find an alternative and safe technique to perform coronary imaging on cardiac ischemic patients. As CO2 angiography has no renal toxicity, it may be a possible solution offering good imaging with negligible collateral effects. Theoretically, by carefully controlling the gas injection process, new automatic injectors may avoid gas reflux into the aorta and possible cerebral damage. A feasibility study is mandatory. A mechanical mock of the coronary circulation was developed and employed. CO2 was injected into the coronary ostium with 2 catheters (2F and 6F) and optical images of bubbles flowing inside the vessels at different injection pressures w...

A simple and innovative way to measure ventricular volume in a mechanical mock of the left ventricle

Abstract Ongoing innovations in mechanical devices to improve the heart’s performance (e.g. left ventricular assist devices, LVAD) require numerical simulations and a bench validation before animal and clinical testing of the device. One of the major requirements of mechanical mocks of the cardiovascular system is the correct evaluation of the parameters of interest (pressure, volumes, flows). This paper presents a new optical method to measure the volume changes of a generic elastic camera through videos acquisition and analysis (using Simpson integration and Matlab software). We tested our proposal with a simple syringe mock of the cardiovascular system under different conditions of simulation dynamics and varying the stroke volumes (SV). We compared our results with those obtained with a standard electromagnetic flowmeter, in terms of instantaneous volume and total SV: the curves presented the same trends (squared Pearson’s coefficients greater than 0.9) with a mean difference less than 5%. The proposed optical method is simple and inexpensive and yields results comparable with those of a standard method.

How to transform a fixed stroke alternating syringe ventricle into an adjustable elastance ventricle

Most devices used for bench simulation of the cardiovascular system are based either on a syringe-like alternating pump or an elastic chamber inside a fluid-filled rigid box. In these devices, it is very difficult to control the ventricular elastance and simulate pathologies related to the mechanical mismatch between the ventricle and arterial load (i.e., heart failure). This work presents a possible solution to transforming a syringe-like pump with a fixed ventricle into a ventricle with variable elastance. Our proposal was tested in two steps: (1) fixing the ventricle and the aorta and changing the peripheral resistance (PHR); (2) fixing the aorta and changing the ventricular elastance and the PHR. The signals of interest were acquired to build the ventricular pressure-volume (P-V) loops describing the different physiological conditions, and the end-systolic pressure-volume relationships (ESPVRs) were calculated with linear interpolation. The results obtained show a good physiological behavior of our mock for both steps. (1) Since the ventricle is the same, the systolic pressures increase and the stroke volumes decrease with the PHR: the ESPVR, obtained by interpolating the pressure and volume values at end-systolic phases, is linear. (2) Each ventricle presents ESPVR with different slopes depending on the ventricle elastance with a very good linear behavior. In conclusion, this paper demonstrates that a fixed stroke alternating syringe ventricle can be transformed into an adjustable elastance ventricle.

A Portable Optical Recording Device Simulating CO2 Angiography for Training Purposes

The last decade has seen a growing interest in the use of carbon dioxide (CO2) as contrast medium for angiography due to the clinical need to avoid nephrotoxic iodine contrast agents and the availability of safer manual injectors and automatic devices [1–6]. Automatic injectors control gas pressures and volumes during injection, allowing vascular surgeons and interventional radiologists to work under safe, controlled and repeatable conditions [5–7]. To avoid potential cerebral ischaemia due to gas embolism, CO2 injection is currently limited to the arteries in the lower body (from the abdominal arteries to the lower extremities) but can be safely injected in veins in all the body since they do not supply the cerebral vasculature [1, 2, 7, 8]. Moreover, the rapid CO2 clearance through the lungs means CO2 angiography can be employed safely not only in patients with renal failure but in virtually all patients. Iodine and CO2 have completely different radiological profiles. Iodine mixes with blood, increasing the linear absorption coefficient of X-Ray and producing a contrast between vessels and tissues in the radiological image. Instead, CO2 produces a contrast between vessels and tissues by displacing the blood from the vessel and not by direct X-ray adsorption. The result is a lower contrast of the radiological image and the need for specific algorithms (subtraction, stacking) to enhance visualization of the vessels [9–11]. The mechanical behaviour of the gas in different size vessels at different injection pressures is currently under investigation and requires a special attention by practitioners performing CO2 angiography [12, 13]. For these reasons, CO2 angiography practitioners require extensive training to optimize the technique. Since training cannot be done on patients and simulators could be difficult to use with radiological equipment, we developed and built a portable mechanical cardiovascular simulator allowing CO2injection in different anatomical and physiological conditions (arterial pressure, heart rate) and concomitant acquisition of optical images by a standard video camera to record the movement of the gas bubbles inside the vessels. By interposing gray transparent films, the optical images are similar to the radiological acquisitions providing information on the accuracy of the injection procedure and the efficiency of different algorithms to yield an optimal final image without the need for X-Ray devices or patients. This paper describes the prototype.

Wavelet analysis of the Valsalva maneuver: Methodology validation and application to pathological subjects

Abstract The autonomic nervous system (ANS) regulates physiologic processes occurring without conscious control through the sympathetic and the parasympathetic systems. Since the ANS is one of the major determinants of heart rate (HR), evaluation of HR variability is a powerful instrument to quantify sympathetic and parasympathetic activations. Traditional techniques in the frequency domain are not applicable to short non-stationary signals like the RR intervals during the Valsalva maneuver (VM). The aim of this work was to validate the wavelet approach in analyzing the VM: 14 healthy subjects and 9 with autonomic failure underwent two or more VMs for a total of 68 tests. A Daubechies-16 form mother wavelet and the powers associated with the sympathetic (LF band) and parasympathetic (HF) activities were calculated. Each VM performed by the same healthy subject presented similar morphologies for the RR series and LF and HF powers. The inter-subject comparison showed a good agreement in morphology with a greater variability in sympathetic and parasympathetic activations. Pathological subjects presented a good RR series repeatability without any correlation in LF and HF powers. The wavelet approach is a good methodology to discriminate normal from pathological subjects and further longitudinal evaluation are required.