A model-based method for myocardium flow estimation.
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Animals↗
Biomedical subjects
A Benassi
Publications and source records attributed to A Benassi.
[Reconstructive surgery in a case of aneurysm of the ascending aorta and aortic valve insufficiency].
The authors report the case of a young patient with an aneurysm of the ascending aorta and moderate aortic incompetence, who underwent a conservative operation at our institution. Dilatation of the sinotubular junction, particularly at the level of the non-coronary sinus of the aortic valve with loss of coaptation between the corresponding leaflet and the two coronary leaflets, was identified at the time of surgery as major cause of valve insufficiency. During surgery, the dilated ascending aorta and pathologic aortic sinus were replaced with a 26 Hemashield prosthesis tailored according to the David guidelines. An intraoperative post-repair transesophageal echo exam showed that the aortic valve appeared to be working competently. The post-operative course was uneventful and at one year, an echographic check of the aortic valve showed that it was fully competent, with normal leaflet motion. Conservative surgery can be a good option in selected patients with ascending aortic aneurysm and aortic valve insufficiency.
Adult↗
Assessment of normal testis growth by quantitative texture analysis of 2-D echo images.
Six phases summarize the evolution of the healthy male gonad. Qualitative examination of two-dimensional echograms detects tonal differences at different ages of the testes. However, routine qualitative evaluation of the echograms is too subjective and dependent upon the scanner controls; on the other hand, simple morphology reports are not sufficient to establish the correct histologic and physiologic evolution. So far computer-assisted quantitative analysis of ultrasonic images has been successful in the characterization of tissues based on their echographic properties; thus this approach could be suitable for an accurate identification of the age of healthy testis. Sixty-two normal subjects, ranked in six groups according to age, underwent echographic examination in standard conditions. Echograms were digitized and analysed by means of well-established algorithms for first and second order statistics. Significant differences in tonal features were found able to discriminate among different ages, in agreement with the qualitative analysis and the histologic reports. Furthermore, some second order analysis features exhibit statistically significant alterations of the micro-structural organisation of the echo patterns consequent to changes of the configuration of the ultrasonic targets, that is, of the gonad's histology. In conclusion, quantitative analysis of echograms can provide a tool for a better assessment of normal testis evolution than the qualitative approach.
Adult↗
Flow quantitation by radio frequency analysis of contrast echocardiography.
Contrast echocardiography has the potential for measuring cardiac output and regional blood flow. However, accurate quantitation is limited both by the use of non-standard contrast agents and by the electronic signal distortion inherent to the echocardiographic instruments. Thus, the aim of this study is to quantify flow by combining a stable contrast agent and a modified echo equipment, able to sample the radio frequency (RF) signal from a region of interest (ROI) in the echo image. The contrast agent SHU-454 (0.8 ml) was bolus injected into an in vitro calf vein, at 23 flow rates (ranging from 376 to 3620 ml/min) but constant volume and pressure. The ROI was placed in the centre of the vein, the RF signal was processed in real time and transferred to a personal computer to generate time-intensity curves. In the absence of recirculation, contrast washout slope and mean transit time (MTT) of curves (1.11-8.52 seconds) yielded excellent correlations with flow: r = 0.93 and 0.95, respectively. To compare the accuracy of RF analysis with that of conventional image processing as to flow quantitation, conventional images were collected in the same flow model by two different scanners: a) the mechanical sector scanner used for RF analysis, and b) a conventional electronic sector scanner. These images were digitized off-line, mean videodensity inside an identical ROI was measured and time-intensity curves were built. MTT by RF was shorter than by videodensitometric analysis of the images generated by the same scanner (p < 0.001). In contrast, MTT by RF was longer than by the conventional scanner (p < 0.001). Significant differences in MTT were also found with changes in the gain setting controls of the conventional scanner. To study the stability of the contrast effect, 6 contrast injections (20 ml) were performed at a constant flow rate during recirculation: the spontaneous decay in RF signal intensity (t1/2 = 64 +/- 8 seconds) was too long to affect MTT significantly. In conclusion, the combination of a stable contrast agent and a modified echocardiographic instrument provides accurate quantitation of flow in an in vitro model; RF analysis is more accurate than conventional processing as to flow quantitation by contrast echocardiography.
Animals↗
Flow quantitation by contrast echocardiography. Effects of intervening tissue and of the angle of incidence between flow and ultrasonic beam.
The combination of a standardized echographic contrast agent with the analysis of the ultrasonic radio frequency (RF) signal allowed in vitro flow quantitation in a circulation model. The purpose of this study was to investigate both the effects of biological tissues, intervening between probe and insonated structure, and the effects of the angle of incidence between flow and ultrasonic beam on RF flow quantitation. Thus, the contrast agent SHU 454 was intravenously injected (0.4 ml) as a bolus into a circulation model, at variable flow rates, while keeping the pressure and volume of the vessel constant. Injections were performed with saline interposed between probe and vessel and after the addition of the subcutaneous tissue of a pig; injections were also performed using the probe normal to the flow and with an angle of incidence of 45 degrees. Echographic data were recorded by a mechanical sector scanner, capable of sampling the RF signal from a region of interest positioned in the center of the vein. Contrast echo time-intensity curves were generated. As expected, both peak intensity and the area under the curves decreased with intervening tissue (-58 and -70% of baseline values, respectively, p < 0.001). Surprisingly, mean transit time also decreased with intervening tissue (from 1.12 +/- 0.25 seconds with saline, to 0.92 +/- 0.13 seconds with tissue, p < 0.001), thus producing a systematic overestimation of flow (21% on the average). To compensate for signal attenuation, contrast injections were repeated in the presence of tissue after increasing the electronic signal amplification (10 dB), and transit time did not significantly differ from control.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Cardiac metastasis of rectal adenocarcinoma. Surgical treatment.
The authors report a case of cardiac metastasis of a rectal adenocarcinoma that infiltrated the right ventricle and partially obstructed its outflow tract. Surgical treatment was performed because of syncopal attacks. The differential diagnosis between organized thrombi and intracardiac tumor is considered.
Adenocarcinoma↗
[Lipids and serum apoproteins in subjects with slight or mild coronary atherosclerosis evaluated with angiography].
In this study 126 subjects (91 males and 35 females, range of age 43-65 years) were studied by coronary angiography. We considered positive for coronary atherosclerosis also patients showing mild or moderate stenosis (> or = 25%). In all subjects we have evaluated serum lipid and apoprotein A-I, B, C-II, C-III and E levels; therefore also cholesterol concentrations in all lipoprotein fractions, separated by sequential ultracentrifugation (VLDL d < 1.006, LDL d 1.006-1.063, HDL d > 1.063 g/ml) and apoprotein B in LDL have been measured. Subjects with coronary atherosclerosis have shown significantly higher levels of total cholesterol, LDL-cholesterol, total cholesterol/HDL-cholesterol and LDL-cholesterol/HDL-cholesterol ratios than controls. Therefore, a lower apo A-I/apo B ratio in males and a higher LDL-apo B levels in females has been found in subjects with coronary atherosclerosis in comparison with controls. The stepwise multiple analysis has demonstrated that LDL-cholesterol levels is the parameter that best correlates with the presence of coronary atherosclerosis. These data confirm the importance of the reduction of LDL-cholesterol levels in primary and secondary prevention of coronary heart disease.
Apolipoproteins↗
Quantitative texture analysis in echocardiography: application to the diagnosis of myocarditis.
Altered myocardial texture associated with inflammatory infiltration or fibrosis of the myocardium has already been described using qualitative and subjective analysis of two-dimensional echocardiograms. The aim of this work is to test whether quantitative analysis of regional image texture in two-dimensional echocardiograms would be an accurate method to identify myocarditis and myocardial fibrosis. A set of 20 two-dimensional studies with endomyocardial biopsy evaluation was examined in 13 patients. Biopsy-proven myocarditis was present in 8 studies; myocarditis and fibrosis in 4; fibrosis in 3; healing/healed myocarditis in 5. A control group of 8 normal subjects was also studied by echocardiography. After quantitative texture analysis of the first order, entropy appeared to consistently differentiate myocarditis from controls. Among second-order parameters, patients affected by myocarditis or fibrosis showed a decreased entropy and higher angular second moment versus controls. We conclude that myocarditis and fibrosis induce similar image texture alterations in ultrasonic images, with increased spatial heterogeneity of the gray level distribution, which can be differentiated from normal structures with digital image analysis techniques.
Adult↗
In vivo identification of mitral valve fibrosis and calcium by real-time quantitative ultrasonic analysis.
Conventional echocardiography provides fundamental information about mitral valve morphology and function but has a relatively low specificity in evaluating valve calcific deposits, which is critical information for the preoperative decision to perform commisurotomy or replacement. In vitro radiofrequency ultrasonic quantitative analysis of the mitral valve has been demonstrated to be a reliable tool in identifying normal, fibrotic and calcific valves. This study evaluates quantitative ultrasound characterization of the mitral valve in vivo. Thirty-three patients, scheduled to undergo mitral valve replacement, and 20 normal subjects (10 young and 10 older control subjects) were studied with a 2.25-MHz transducer. Radiofrequency signal was analyzed by a microprocessor system (used with an M-mode commercially available echocardiograph) for on-line evaluation of ultrasonic backscatter with 8 bits of amplitude resolution, 40-MHz sampling rate and a 1-microsecond acquisition gate. The integrated value of the rectified radiofrequency signal amplitude was deemed the integrated backscatter index. The highest value recorded with the ultrasonic analysis from each valve was taken as representative and expressed as the percent value with respect to the pericardial integrated backscatter index value of that subject. The 33 excised mitral valves underwent histologic examination. Four groups were identified: young controls (group I, n = 10); older controls age-matched with patients (group II, n = 10); patients with fibrotic mitral valves (group III, n = 13); and patients with calcific mitral valves (group IV, n = 20).(ABSTRACT TRUNCATED AT 250 WORDS)
Calcinosis↗
In vivo quantitative ultrasonic evaluation of myocardial fibrosis in humans.
The aim of this study was to assess in vivo whether the regional ultrasonic reflectivity, evaluated by a real-time integrated backscatter analysis, was related to the local content of connective tissue in human myocardium as estimated by quantitative histology of endomyocardial biopsies. Sixteen patients with presumptive diagnosis of cardiomyopathy were ultrasonically studied by means of an M-mode-based echocardiographic system with quantitative integrated backscatter analysis capabilities. A 2.25-MHz transducer was used. The integrated value of the rectified radiofrequency signal of the interventricular septum was taken as integrated backscatter index and expressed in percent normalized for the pericardial interface (assumed to be 100%). All patients also underwent multiple left ventricular endomyocardial biopsies, which were stained with Masson's trichrome and studied with the use of a computer-assisted image analysis system. The percent integrated backscatter index was significantly higher in the presence of connective tissue area greater than 20% (eight patients) versus less than 20% (eight patients): 51 +/- 25% versus 26 +/- 11%, p less than 0.05. A significant correlation (p less than 0.05, R = 0.55) was found between percent integrated backscatter index and percent connective tissue area. In vivo on-line quantitative ultrasound analysis is feasible in man and reliably identifies variations in the regional extent of fibrosis in human myocardium.
Adolescent↗
Oxidative stress in the rat heart, studies on low-level chemiluminescence.
Detection of ultraweak chemiluminescence (CL) emission from the surface of the organ is a sensitive and non-disruptive tool to evaluate the oxidative stress in rat heart. Indeed, an increased photon emission rate can be observed when cellular antioxidants such as glutathione or vitamin E are depleted, or when organic hydroperoxides are infused. We used CL recording to demonstrate in rat heart that: (i) different diets may lead to different heart sensitivity to an oxidative stress; and (ii) post-ischaemic reoxygenation induces an oxidative stress. CL emission induced by an oxidative stress is accompanied by an increased release of eicosanoids. However, while non-steroid anti-inflammatory drugs (aspirin, indomethacin and ibuprofen) prevented eicosanoid release, these compounds dramatically enhanced hydroperoxide-dependent CL. The nature of this phenomenon is still obscure, but the increase of steady-state concentration of excited species caused by anti-inflammatory drugs seems to be pathophysiologically relevant, since in all our experimental conditions tissue damage was proportional to CL emission rate.
Animals↗
Frequency domain analysis of contrast echocardiographic images.
Sequences of echocontrastographic images of the dog's myocardium are analysed in the frequency domain for the identification of underperfused areas. Owing to the fact that echo images are contaminated by noise and artifacts, we have applied filtering techniques based on Fourier's methods in sequences of raw frames recorded during perfusion with a contrast agent. Thus we have been able to assess correctly the spatial and temporal distribution of the contrast, i.e. the agent kinetics which parallel the distribution of coronary blood flow, in terms of the time necessary for the flow gradient to reach its maximum value, and to describe such a distribution by a functional image obtained by means of an original procedure.
Algorithms↗
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.
Adult↗
Time domain echo pattern evaluations from normal and atherosclerotic arterial walls: a study in vitro.
The aim of this study in vitro of human fresh specimens was to quantitatively evaluate the contribution of the aqueous phase-intima interface (the first 400 msec of the reflected signal) in normal and atherosclerotic arterial walls. Seventy-five samples were studied, 15 normal, 15 fatty, 15 fibrofatty, 15 fibrous, and 15 calcific. A broadband transducer (4 to 14 MHz) was used. The aqueous phase-intima reflection (expressed in dB, mean +/- SD) was lowest in the fatty plaques (-35.3 +/- 2.5), differing in a highly significant way from that in all other groups: normal (-13.2 +/- 8.8), fibrofatty (-20.4 +/- 8.3), fibrous (-13.0 +/- 9.7), calcific (-5.9 +/- 3.4). The echo coming from the intima-media transition was of relatively low amplitude in normal and in fatty samples; typically, strong reflections from the intima-media transitions were present in the other pathologic subsets. In conclusion, the time domain echo pattern of the arterial wall may provide a useful clue to the structure of the plaque.
Aorta↗
Effect of dietary fats on hydroperoxide-induced chemiluminescence emission and eicosanoid release in the rat heart.
The effect of diets supplemented with three different fats (olive oil, sunflower oil, pork fat) on the susceptibility of the rat heart to oxidative stress and on the rate of eicosanoid release were studied. Our results show that when fatty-acid unsaturation of heart lipids is increased or vitamin E is decreased, even to a low degree, a marked enhancement of the susceptibility to hydroperoxide-induced oxidative stress (measured by chemiluminescence emission) occurs, which is associated with an increase of eicosanoid release from the heart.
Animals↗
On-line two-dimensional evaluation of ultrasonic integrated backscatter.
We describe an apparatus for the on-line evaluation of integrated backscatter from areas of tissue. The equipment is fully integrated into a B-mode ultrasonic system; there are therefore no new operating procedures to be learned. It provides a simultaneous display of conventional information, together with parameters of tissue characterization. The apparatus is fast and, over a broad diagnostic frequency range, may be used in conjunction with conventional equipment employing transducers.
Humans↗
[Recording of signals in ambulatory electrocardiography].
The different techniques for the acquisition of electrocardiographic signal in ambulatory monitoring are described in this paper. Direct and, frequency modulation systems are explained in details with their relative advantages and disadvantages. The basis of digital sampling and real time analysis of ECG signals are also explained.
Electrocardiography↗
[Technical ambulatory ECG innovations in performance evaluation].
Evaluating the performances of the instrumentation for Ambulatory ECG (AECG) analysis is a need largely recognized by both manufacturers and users. The most generally accepted method is the beat-by-beat comparison with annotated data bases, representing the different ECG abnormalities. Available data bases are aimed at arrhythmias detection evaluation, while it is recognized that the AECG ST-T changes detection has a great relevance in the analysis of ischemic heart disease. A concerted action of the European Community on Ambulatory Monitoring has been approved for achieving a comprehensive reference standard for assessing the quality of AECG instrumentation. The European project has been concentrated on the problem of ST-T analysis. An annotated data base is being developed with the contribution of european experts. A pilot study has been performed for establishing the criteria related to the development and annotation; particularly the definition of significant ST-T changes has been established. The data base will include 2-hour double channel AECG records, which contain at least one ST-T episode. Each record is annotated beat by beat according to the established scheme, identifying arrhythmic beats, rhythm changes, ST-T changes and noisy segments. A coordinating center has been established for interacting with the participating groups and for performing the operations related to the generation and management of the data base. For the time being 14 Groups of 8 Countries are participating to the annotation of the data base. A minimum number of 100 records is planned within June 1988.
Algorithms↗