Vincenzo Gemignani

Bio: Vincenzo Gemignani is an academic researcher from National Research Council. The author has contributed to research in topics: Central moment & Edge detection. The author has an hindex of 15, co-authored 50 publications receiving 954 citations. Previous affiliations of Vincenzo Gemignani include University of Brescia.

A System for Real-Time Measurement of the Brachial Artery Diameter in B -Mode Ultrasound Images

Abstract: The measurement of the brachial artery diameter is frequently used in clinical studies for evaluating the flow-mediated dilation and, in conjunction with the blood pressure value, for assessing arterial stiffness. This paper presents a system for computing the brachial artery diameter in real-time by analyzing B-mode ultrasound images. The method is based on a robust edge detection algorithm which is used to automatically locate the two walls of the vessel. The measure of the diameter is obtained with subpixel precision and with a temporal resolution of 25 samples/s, so that the small dilations induced by the cardiac cycle can also be retrieved. The algorithm is implemented on a standalone video processing board which acquires the analog video signal from the ultrasound equipment. Results are shown in real-time on a graphical user interface. The system was tested both on synthetic ultrasound images and in clinical studies of flow-mediated dilation. Accuracy, robustness, and intra/inter observer variability of the method were evaluated

Real-time Measurement System for Evaluation of the Carotid Intima-Media Thickness With a Robust Edge Operator

Abstract: Objective. The purpose of this report is to describe an automatic real-time system for evaluation of the carotid intima-media thickness (CIMT) characterized by 3 main features: minimal interobserver and intraobserver variability, real-time capabilities, and great robustness against noise. Methods. One hundred fifty carotid B-mode ultrasound images were used to validate the system. Two skilled operators were involved in the analysis. Agreement with the gold standard, defined as the mean of 2 manual measurements of a skilled operator, and the interobserver and intraobserver variability were quantitatively evaluated by regression analysis and Bland-Altman statistics. Results. The automatic measure of the CIMT showed a mean bias ± SD of 0.001 ± 0.035 mm toward the manual measurement. The intraobserver variability, evaluated with Bland-Altman plots, showed a bias that was not significantly different from 0, whereas the SD of the differences was greater in the manual analysis (0.038 mm) than in the automatic analysis (0.006 mm). For interobserver variability, the automatic measurement had a bias that was not significantly different from 0, with a satisfactory SD of the differences (0.01 mm), whereas in the manual measurement, a little bias was present (0.012 mm), and the SD of the differences was noticeably greater (0.044 mm). Conclusions. The CIMT has been accepted as a noninvasive marker of early vascular alteration. At present, the manual approach is largely used to estimate CIMT values. However, that method is highly operator dependent and time-consuming. For these reasons, we developed a new system for the CIMT measurement that conjugates precision with real-time analysis, thus providing considerable advantages in clinical practice. Key words: carotid artery; edge detection; intima-media thickness; real-time ultrasound imaging; thickness measurement.

Assessment of flow-mediated dilation reproducibility: a nationwide multicenter study

Abstract: Objective: Impaired flow-mediated dilation (FMD) isassociated with cardiovascular risk factors and providesprognostic information. Despite the noninvasive nature ofthis technique, a major limitation to its widespread use islow reproducibility. The aim of this study was to evaluateimpact of methodological standardization amongdifferent investigation sites on brachial artery FMDreproducibility.Methods: Seven Italian centers recruited 135 healthyvolunteers, aged 20–60 years. FMD was assessed byhigh-resolution ultrasound equipped with a stereotacticprobe-holding device. Certified sonographers recordedbrachial artery scans at baseline (day 1a), 1 h after (day1b), and 1 month later (day 30). Endothelium-independentvasodilation (EIVD) to sublingual glyceril-trinitrate wasrecorded at day 1 and day 30. FMD and EIVD were blindlyevaluated at the coordinating center by an automatededge detection system. The intra-session (day 1a versus1b) and inter-session (day 1a versus 30) coefficients ofvariation were calculated.Results: FMD was not significantly (P¼0.91) differentat day 1a, day 1b and day 30 (6.52 2.9, 6.42 3.1,6.57 2.8%, respectively). The FMD intra-sessioncoefficient of variation was 9.9 8.4% (from 7.6 to11.9% across centers). The FMD inter-session coefficient ofvariation was 12.9 11.6% (from 11.6 to 16.1% acrosscenters). Inter-session coefficient of variation for EIDV was19.7 16.8%.Conclusions: This study shows a homogeneous coefficientof variation for FMD among different centers. The inter-session coefficient of variation was similar to the intra-session coefficient of variation, representing the intrinsicFMD variability. We demonstrate for the first time thatrigorous and standardized procedure may providereproducible FMD assessment to study endothelial functionin multicenter clinical trials.Keywords: endothelial function, flow-mediated dilation,multicenter study, reproducibilityAbbreviations: ANOVA, analysis of variance; BP, bloodpressure; CI, confidence intervals; EIDV, endothelium-independent vasodilation; FMD, flow mediated dilation;GTN, glyceril trinitrate; SD, standard deviation

Assessment of carotid stiffness and intima-media thickness from ultrasound data: comparison between two methods.

Abstract: Objective. Increased arterial stiffness and carotid intima-media thickness (IMT) are considered independent predictors of cardiovascular events. The aim of this study was to compare a system recently developed in our laboratory for automatic assessment of these parameters from ultrasound image sequences to a reference radio frequency (RF) echo-tracking system. Methods. Common carotid artery scans of 21 patients with cardiovascular risk factors and 12 healthy volunteers were analyzed by both devices for the assessment of diameter (D), IMT, and distension (ΔD). In the healthy volunteers, analyses were repeated twice to evaluate intraobserver variability. Agreement was evaluated by Bland-Altman analysis, whereas reproducibility was expressed as a coefficient of variation (CV). Results. Regarding the agreement between the two systems, bias values ± SD were 0.060 ± 0.110 mm for D, –0.006 ± 0.039 mm for IMT, and –0.016 ± 0.039 mm for ΔD. Intraobserver CVs were 2% ± 2% for D, 5% ± 5% for IMT, and 6% ± 6% for ΔD with the RF echo-tracking system and 2% ± 1% for D, 6% ± 6% for IMT, and 8% ± 6% for ΔD with our automated system. Conclusions. Although B-mode-based devices are less precise than RF-based ones, our automated system has good agreement with the reference method and comparable reproducibility, at least when high-quality images are analyzed. Hence, this study suggests that the presented system based on image processing from standard ultrasound scans is a suitable device for measuring IMT and local arterial stiffness parameters in clinical studies. Key words: B-mode; carotid stiffness; intima-media thickness; radio frequency echo tracking; ultrasound.

Diastolic time – frequency relation in the stress echo lab: filling timing and flow at different heart rates

Abstract: A cutaneous force-frequency relation recording system based on first heart sound amplitude vibrations has been recently validated. Second heart sound can be simultaneously recorded in order to quantify both systole and diastole duration. 1- To assess the feasibility and extra-value of operator-independent, force sensor-based, diastolic time recording during stress. We enrolled 161 patients referred for stress echocardiography (exercise 115, dipyridamole 40, pacing 6 patients). The sensor was fastened in the precordial region by a standard ECG electrode. The acceleration signal was converted into digital and recorded together with ECG signal. Both systolic and diastolic times were acquired continuously during stress and were displayed by plotting times vs. heart rate. Diastolic filling rate was calculated as echo-measured mitral filling volume/sensor-monitored diastolic time. Diastolic time decreased during stress more markedly than systolic time. At peak stress 62 of the 161 pts showed reversal of the systolic/diastolic ratio with the duration of systole longer than diastole. In the exercise group, at 100 bpm HR, systolic/diastolic time ratio was lower in the 17 controls (0.74 ± 0.12) than in patients (0.86 ± 0.10, p < 0.05 vs. controls). Diastolic filling rate increased from 101 ± 36 (rest) to 219 ± 92 ml/m2* s-1 at peak stress (p < 0.5 vs. rest). Cardiological systolic and diastolic duration can be monitored during stress by using an acceleration force sensor. Simultaneous calculation of stroke volume allows monitoring diastolic filling rate. Stress-induced "systolic-diastolic mismatch" can be easily quantified and is associated to several cardiac diseases, possibly expanding the spectrum of information obtainable during stress.

Determinants of pulse wave velocity in healthy people and in the presence of cardiovascular risk factors

Abstract: Aims Carotid–femoral pulse wave velocity (PWV), a direct measure of aortic stiffness, has become increasingly important for total cardiovascular (CV) risk estimation. Its application as a routine tool for clinical patient evaluation has been hampered by the absence of reference values. The aim of the present study is to establish reference and normal values for PWV based on a large European population. Methods and results We gathered data from 16 867 subjects and patients from 13 different centres across eight European countries, in which PWV and basic clinical parameters were measured. Of these, 11 092 individuals were free from overt CV disease, non-diabetic and untreated by either anti-hypertensive or lipid-lowering drugs and constituted the reference value population, of which the subset with optimal/normal blood pressures (BPs) (n = 1455) is the normal value population. Prior to data pooling, PWV values were converted to a common standard using established conversion formulae. Subjects were categorized by age decade and further subdivided according to BP categories. Pulse wave velocity increased with age and BP category; the increase with age being more pronounced for higher BP categories and the increase with BP being more important for older subjects. The distribution of PWV with age and BP category is described and reference values for PWV are established. Normal values are proposed based on the PWV values observed in the non-hypertensive subpopulation who had no additional CV risk factors. Conclusion The present study is the first to establish reference and normal values for PWV, combining a sizeable European population after standardizing results for different methods of PWV measurement.

Recommendations for Improving and Standardizing Vascular Research on Arterial Stiffness: A Scientific Statement From the American Heart Association

Abstract: Much has been published in the past 20 years on the use of measurements of arterial stiffness in animal and human research studies. This summary statement was commissioned by the American Heart Association to address issues concerning the nomenclature, methodologies, utility, limitations, and gaps in knowledge in this rapidly evolving field. The following represents an executive version of the larger online-only Data Supplement and is intended to give the reader a sense of why arterial stiffness is important, how it is measured, the situations in which it has been useful, its limitations, and questions that remain to be addressed in this field. Throughout the document, pulse-wave velocity (PWV; measured in meters per second) and variations such as carotid-femoral PWV (cfPWV; measured in meters per second) are used. PWV without modification is used in the general sense of arterial stiffness. The addition of lowercase modifiers such as “cf” is used when speaking of specific segments of the arterial circulation. The ability to measure arterial stiffness has been present for many years, but the measurement was invasive in the early times. The improvement in technologies to enable repeated, minimal-risk, reproducible measures of this aspect of circulatory physiology led to its incorporation into longitudinal cohort studies spanning a variety of clinical populations, including those at extreme cardiovascular risk (patients on dialysis), those with comorbidities such as diabetes mellitus (DM) and hypertension, healthy elders, and general populations. In the ≈3 decades of clinical use of PWV measures in humans, we have learned much about the importance of this parameter. PWV has proven to have independent predictive utility when evaluated in conjunction with standard risk factors for death and cardiovascular disease (CVD). However, the field of arterial stiffness investigation, which has exploded over the past 20 years, has proliferated without logistical guidance for clinical and …

Expert consensus and evidence-based recommendations for the assessment of flow-mediated dilation in humans

Abstract: Endothelial dysfunction is involved in the development of atherosclerosis, which precedes asymptomatic structural vascular alterations as well as clinical manifestations of cardiovascular disease (CVD). Endothelial function can be assessed non-invasively using the flow-mediated dilation (FMD) technique. Flow-mediated dilation represents an endothelium-dependent, largely nitric oxide (NO)-mediated dilatation of conduit arteries in response to an imposed increase in blood flow and shear stress. Flow-mediated dilation is affected by cardiovascular (CV) risk factors, relates to coronary artery endothelial function, and independently predicts CVD outcome. Accordingly, FMD is a tool for examining the pathophysiology of CVD and possibly identifying subjects at increased risk for future CV events. Moreover, it has merit in examining the acute and long-term impact of physiological and pharmacological interventions in humans. Despite concerns about its reproducibility, the available evidence shows that highly reliable FMD measurements can be achieved when specialized laboratories follow standardized protocols. For this purpose, updated expert consensus guidelines for the performance of FMD are presented, which are based on critical appraisal of novel technical approaches, development of analysis software, and studies exploring the physiological principles underlying the technique. Uniformity in FMD performance will (i) improve comparability between studies, (ii) contribute to construction of reference values, and (iii) offer an easy accessible and early marker of atherosclerosis that could complement clinical symptoms of structural arterial disease and facilitate early diagnosis and prediction of CVD outcomes.