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At least 847 records · Page 47Linked to original sources

PubMed1989

Pseudo-three-dimensional reconstruction of ultrasonic images of the tongue.

The purpose of the present investigation was to develop a method for the three-dimensional reconstruction of the surface of the tongue using serial ultrasonic images gathered during the production of the sustained fricative /s/. Using a phased linear array ultrasonic monitoring system, transducer position, subject position, and ultrasonic scan data were recorded simultaneously on composite video for off-line analysis. Reconstruction of a series of ultrasound images was completed using a microcomputer programmed to transform the ultrasonic image contours into three-dimensional space. Additional transformations converting the three-dimensional tongue contours into two dimensions for screen plotting were also developed. Results are discussed in light of previously reported models of the tongue surface.

Adult↗

PubMed1991

An ultrasonic method to measure human plasma coagulation time.

An ultrasonic method to measure coagulation time for prothrombin time (PT) is discussed. This method is based on the measurement of ultrasonic scattering from spherical glass particles of 200-microns diameter kept in motion, inside of a holder containing 0.1 ml of plasma, by ultrasonic energy. The incident wave (2.7 MHz) not only keeps the particle in motion but also is the source for the scattered waves. A receiving transducer captures part of the scattered wave and generates at its electrical output a signal containing amplitude and phase fluctuations. The motion of the particles are strongly influenced by the rheological changes during the process of coagulation. When the clot is formed, the amplitude of the motion of these particles is significantly reduced and so the fluctuations on the received signal stop. The time from the start of the coagulation process until the end of the fluctuations at the received signal is the coagulation time. Experimental results demonstrate that the ultrasonic method has precision and accuracy compatible to those provided by the manual tilt-tube method when PT is measured with normal and abnormal samples of human plasma.

Factor V Deficiency↗

PubMed1996

Anisotropy of the slope of ultrasonic attenuation in formalin fixed human myocardium.

Clinical implementation of quantitative ultrasonic tissue characterization is likely to require imaging the heart with sound propagating at varying angles relative to the fibers of the heart. Under these circumstances, the variation of the ultrasonic properties of myocardium with the angle of propagation relative to the myofibers may represent a significant source of potential misinterpretation. In the present study, the systematic approach of assessing the impact of anisotropy on quantitative myocardial tissue characterization is extended by reporting results of a recent in vitro study to measure the anisotropy of the slope of ultrasonic attenuation in specimens of formalin fixed human myocardium. Data obtained from regions of remote infarct are presented and compared to data acquired from regions identified to be free of infarct. The slope of attenuation for both regions exhibit a sinusoid-like dependence on angle that is approximately doubled for propagation parallel to the fibers as compared to perpendicular. These results are, in turn, compared to an earlier study from the laboratory that examined the effects of myocardial infarction on ultrasonic attenuation and interstitial collagen content in freshly excised canine hearts. Discussion regarding the analysis and interpretation of measurements of slope of attenuation is presented as well as a discussion of the possible influence of formalin fixation on our results.

Animals↗

PubMed1999

Volumetric imaging with ultrasonic spiral CT.

To examine the feasibility of implementing spiral computed tomography (CT) in ultrasonic imaging as a potential method for breast screening, an algorithm for x-ray spiral CT was applied to ultrasonic waves on a specially built ultrasonic tomographic system. Three-dimensional reconstructions of various phantoms were obtained. Spiral ultrasonic CT is feasible, and it may have clinical merit as a breast imaging method.

Algorithms↗

PubMed1989

Ultrasonic determination of the residual bladder volume.

In a clinical study the ultrasonic determination of the residual bladder volume is evaluated by applying several echographic methods described in the literature. 163 patients (age 3-89 years, 114 males and 49 females) and 13 students were examined. Only in the latter group the bladder volume was also determined by a planimetric method. The most practical method showed a good agreement (with a maximum deviation of 25%) between the ultrasonically measured volumes and the volumes measured by catheterization in 66% of the cases. This method makes use of the formula Vus = 0.5(Vt + Vl), where Vus = residual volume estimated by ultrasonography; Vt = volume measured by the computer using the largest transversal ultrasonic bladder section, and Vl = volume measured for the largest longitudinal section). Factors that influence image quality and accuracy because of changes in the form of the bladder were analyzed. The magnitude of the residual volume determined the image quality and the accuracy above all: lower volumes give worse images and are less accurate. Other factors seem to be relatively unimportant. To avoid discomfort, caused by urine tract infection and urethral strictures, ultrasonic determination of the residual urine is recommended for clinical application.

Female↗

PubMed1993

Ultrasonic testicular texture and size in 444 men from the general population: correlation to semen quality.

Scrotal ultrasonography was performed in 888 testes of 444 randomly selected men appearing before the medical board prior to military service (Mili group, 287 men, median age 18.8 years), and in employees from an industrial company (Empl group, 157 men, median age 35.6 years). The ultrasonic volume of each testis was calculated from 3 perpendicular measurements. The ultrasonic texture on sectional planes was scored using a scale from 1 to 5, 1 being very regular, 2 slightly irregular, 3 moderately irregular, 4 very irregular or with bright echogenic points, and 5 with demarcated tumor suspicious areas. Orchidometer measurements were performed in 258 men in Mili group, and semen samples were obtained from 121 men in Empl group. The ultrasonic volume of the right testis (median 14.1 ml, range 3.0-31.4 ml) was bigger than that of the left testis (median 13.0 ml, range 3.5-35.2). The volume was dependent on age for men under 20 years, but not for men aged 20 years or more. The subgroup of men with a history of cryptorchidism had a smaller average testicular volume (median 10.5 ml) compared with men with normal descent (median 14.1 ml). Ultrasonic volume was positively correlated to the total sperm count in the ejaculate, to sperm penetration in egg white, and to normal sperm morphology. The echo score distribution showed slightly higher scores in Empl for both the right and the left testis. Men in Empl group were older, and it could not be precluded that this difference was due to age.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed2003

Incremental value of ultrasonic tissue characterization (backscatter) in the evaluation of left ventricular myocardial structure and mechanics in essential arterial hypertension.

BACKGROUND: Ultrasonic backscatter parameters were analyzed in hypertensive patients and divided into groups according to both severity of left ventricular hypertrophy (LVH) (group A: no LVH [n=52]; B: mild to moderate LVH [n=55]; and C: severe LVH [n=10]) and left ventricular geometry (normal geometry [n=44]; concentric remodeling [n=8]; concentric hypertrophy [n=25]; and eccentric hypertrophy [n=40]). METHODS AND RESULTS: We studied 117 male, essential hypertensive patients and 19 normotensive, age-matched (40+/-5 years), healthy subjects who served as controls. Ambulatory and office blood pressure measurements were taken and 2-dimensional Doppler echocardiography and ultrasonic myocardial integrated backscatter (IBS) were performed. A group from the hypertensive study population (n=16) was observed after a period of pharmacological antihypertensive treatment to determine the behavior of backscatter parameters in relation to eventual regression of left ventricular mass (LVM). The cyclic variation index (CVIs) of the backscatter signal at the septum level was grouped according to each LVM level and was 29.4+/-9.3 (controls), 15+/-11 (group A), 9.5+/-10 (group B), and -1.5+/-8.6 (group C) (P<0.001). CVI septum values grouped according to left ventricular geometry were 15+/-11 (normal geometry), 12+/-7 (concentric remodeling), 7+/-11 (concentric hypertrophy), and 7.8+/-11 (eccentric hypertrophy) (P<0.01). Follow-up data demonstrate a significant reduction of LVM after therapy, as well as a significant increase in CVIs toward normal values. CONCLUSIONS: Hypertensive patients with higher LVM had the worst prognosis; in fact, those patients had the most significant CVI alterations. Regression of LVM subsequent to chronic pharmacological therapy induces a normalization of ultrasonic backscatter parameters. Ultrasonic tissue characterization (backscatter) analysis could allow early identification of patients at risk of developing complications of hypertensive cardiopathy.

Adult↗

PubMed1985

Assessment of fibrosis in infarcted human hearts by analysis of ultrasonic backscatter.

In animal hearts, the magnitude of integrated ultrasonic backscatter is increased in fibrotic myocardium. Our purpose in this study was to quantitate the relationship between ultrasonic backscatter and collagen deposition in 10 excised human hearts with old infarcts. A 2.25 MHz, 50% fractional bandwidth transducer was positioned at the transducer focal distance from the epicardium of each specimen. The radio frequency backscatter signal was digitized, squared, and integrated to yield the integrated ultrasonic backscatter, which was referenced to the backscatter from a water/steel interface. The interrogated myocardium was then excised and divided into two portions. One portion was assayed for hydroxyproline, a marker for collagen. A second portion was sectioned, stained with Masson's trichrome, and studied with the use of a computer-assisted image analysis system. There was a linear correlation between the magnitude of integrated backscatter and myocardial collagen content estimated by hydroxyproline assay (r = .78). Quantitative histologic analysis revealed a variable relationship between the transmural distribution of collagen and the corresponding transmural pattern of the backscatter signal. In two specimens exhibiting a discrete layer of subendocardial fibrosis, the backscatter amplitude was also increased in the subendocardial region. In specimens with other patterns of fibrosis, the local backscatter amplitude did not correspond to the transmural pattern of collagen distribution. We conclude that the quantitative analysis of ultrasonic backscatter shows promise for the noninvasive evaluation of myocardial fibrosis after infarction.

Collagen↗

PubMed1987

Quantitative ultrasonic tissue characterization with real-time integrated backscatter imaging in normal human subjects and in patients with dilated cardiomyopathy.

We have shown previously that the physical properties of myocardium in dogs can be characterized with quantitative ultrasonic integrated backscatter and that interrogation of the tissue with ultrasound can delineate cardiac cycle-dependent changes in ultrasonic backscatter in normal tissue that disappear with ischemia and reappear with reperfusion if functional integrity is restorable. To determine whether this approach can be applied to man, we implemented an automatic gain compensation and continuous data acquisition system to characterize myocardium with quantitative ultrasonic backscatter and to detect cardiac cycle-dependent changes in real time. We developed a two-dimensional echocardiographic system with quantitative integrated backscatter imaging capabilities for use in human subjects that can automatically differentiate ultrasonic signals from blood as opposed to those obtained from tissue and adjust the slope of the gain compensation appropriately. Real-time images were formed from a continuous signal proportional to the logarithm of the integrated backscatter along each A-line. In our initial investigation, 15 normal volunteers (ages 17 to 40 years, heart rates 44 to 88 beats/min) and five patients with dilated cardiomyopathy (ages 22 to 52, heart rates 82 to 120 beats/min) were studied with conventional parasternal long-axis echocardiographic views. Diastolic-to-systolic variation of integrated backscatter in the interventricular septum and left ventricular posterior wall was seen in each of the normal subjects averaging 4.6 +/- 1.4 dB (SD) and 5.3 +/- 1.5 dB (n = 127 sites), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1992

Structural remodeling of human myocardial tissue after infarction. Quantification with ultrasonic backscatter.

BACKGROUND: Remodeling of myocardial tissue after infarction may culminate in the development of either a well-healed scar or a thin, expanded heart wall segment that predisposes to ventricular aneurysm formation, congestive heart failure, or ventricular tachycardia. The three-dimensional architecture of mature human infarct tissue and the mechanisms that determine it have not been elucidated. We have previously shown that quantitative ultrasonic backscatter can be used to define the transmural organization of human myofibers in the normal ventricular wall by measuring the dependence of backscatter on the angle of insonification, or ultrasonic anisotropy. We propose that measurement of ultrasonic anisotropy of backscatter may permit quantitative characterization of the transmural architecture of tissue from areas of myocardial infarction and facilitate identification of fundamental mechanisms of remodeling of the ventricular wall. METHODS AND RESULTS: We measured integrated backscatter in 33 transmural sections from 12 cylindrical biopsy specimens (1.4-cm diameter) sampled from central regions of mature infarction in six explanted fixed human hearts. Tissue samples were insonified in two-degree steps around their entire circumference at successive transmural levels with a 5-MHz broad-band piezoelectric transducer. Backscatter radio frequency data were gated from the center of each specimen, and spectral analysis was performed on the gated radio frequency for the computation of integrated backscatter. Histological morphometric analysis was performed on each specimen for determination of the predominant fiber orientation and the percentage of tissue infarcted at consecutive transmural levels. The average percentage of tissue infarcted for all transmural levels was 49 +/- 3% (range, 13-80%). Histological attributes varied from patchy fibrosis to extensive confluent zones of scar tissue. The angle-averaged integrated backscatter for all transmural levels in infarct tissue was approximately 5 dB greater than that previously measured in normal tissue in our laboratory (-48.3 +/- 0.5 versus -53.4 +/- 0.4 dB, infarct versus normal). Marked anisotropy of backscatter was observed in tissue from areas of infarction and was characterized by a sinusoid-like dependence on the angle of insonification at each transmural level. Insonification perpendicular to infarct fibers yielded values for integrated backscatter 14.8 +/- 0.5 dB greater than those for insonification parallel to these fibers. Juxtaposition of the sinusoid-like anisotropy functions from all consecutive transmural levels demonstrated a progressive shift in the orientation of scar tissue elements from epicardial to endocardial levels of 14.6 +/- 1.5 degrees/mm of tissue. The transmural shift in fiber orientation per millimeter of tissue from the area of infarction exceeded that previously measured for normal tissue (9.2 +/- 0.7 degrees/mm) by 59%. This marked augmentation in angular shift per millimeter of tissue results from a generalized structural rearrangement (or reorientation) of fibers across the entire ventricular wall in the infarct zone that we hypothesize is determined in part by dynamic mechanical forces, imposed by the surrounding functional normal tissue, that tether the "infarcted" tissue. CONCLUSIONS: Myocardial tissue from areas of myocardial infarction manifests substantial anisotropy of ultrasonic scattering that may be useful for quantitative characterization of the alignment and overall three-dimensional anatomic organization of mature infarct scars.

Biopsy↗

PubMed2002

Carotid plaque ultrasonic heterogeneity and severity of stenosis.

BACKGROUND AND PURPOSE: Several studies have reported on the correlation of ultrasonic carotid plaque morphology, cerebrovascular symptoms, and intraplaque hemorrhage. This study correlates ultrasonic carotid plaque morphology with the degree of carotid stenosis. METHODS: Carotid arteries (n=2460) were examined by using color duplex ultrasound during a 1-year period. Carotid stenoses were classified into <50%, 50% to <60%, 60% to <70%, and >70% to 99%. Ultrasonic plaque morphology was characterized as either heterogeneous (mixed hyperechoic, hypoechoic, and isoechoic) or homogeneous. RESULTS: Heterogeneous plaques were noted in 138 of 794 arteries with <50% stenosis, in 191 of 564 arteries with 50% to <60% stenosis, in 301 of 487 arteries with 60% to <70% stenosis, and in 496 of 615 arteries with 70% to 99% stenosis. The higher the degree of stenosis, the more likely it is to be associated with heterogeneous plaques. Heterogeneous plaques were present in 59% of the arteries with > or =50% stenoses versus 17% of the arteries with <50% stenoses, in 72% of the arteries with > or =60% stenoses versus 24% of the arteries with <60% stenosis, and in 80% of the arteries with > or =70% stenoses versus 34% of the arteries with <70% stenoses (P<0.0001 and odds ratios of 6.9, 8.1, and 8.0, respectively). Heterogeneous plaques were associated with an incidence of symptoms that was higher than that for homogeneous plaques for all grades of stenoses; percentages were, respectively, as follows: 68% versus 16% for <50% stenosis; 76% versus 21% for 50% to <60% stenosis; 79% versus 23% for 60% to <70% stenosis, and 86% versus 31% for > or =70% to 99% stenosis (P<0.0001 and odds ratios of 8.9, 11.9, 12.6, and 13.7, respectively). Heterogeneity of plaques was more positively correlated with symptoms than with any degree of stenosis (regardless of plaque structure). Eighty percent of all heterogeneous plaques were symptomatic versus 58% for all stenoses > or =50%, 68% for all stenoses > or =60%, and 75% for all stenoses > or =70% (P<0.0001, P<0.0001, and P=0.02, respectively). CONCLUSIONS: The higher the degree of carotid stenosis, the more likely it is to be associated with ultrasonic heterogeneous plaque and cerebrovascular symptoms. Heterogeneity of the plaque was more positively correlated with symptoms than with any degree of stenosis. These findings suggest that plaque heterogeneity should be considered in selecting patients for carotid endarterectomy.

Carotid Arteries↗

PubMed1988

Ultrasonically guided needle biopsy in the diagnosis of mediastinal masses.

The value of ultrasonic examination and ultrasonically guided needle biopsy (UGNB) of mediastinal masses was investigated in 45 patients. Fifteen of the masses were malignant and 30 were benign. The diagnoses were histologically confirmed by examination of surgical or autopsy specimens. Only teratoma could be confidently diagnosed by ultrasonography alone. Diagnosis of other types of mediastinal masses required examination of tissue samples. Using ultrasonically guided aspiration biopsy (UGAB), we were able to diagnose 13 of 15 malignant tumors and 18 of 27 benign mediastinal masses. Ultrasonically guided cutting biopsy was performed in conjunction with UGAB in 11 patients, and the diagnosis was histologically confirmed in 9 cases. Complications with UGNB occurred in only 1 case. Our results indicate that UGNB is a safe, simple technique that can be applied to most of the mediastinal masses. We believe that it is the method of choice in such cases.

Biopsy, Needle↗

PubMed2005

A randomised controlled trial to explore attitudes to routine scale and polish and compare manual versus ultrasonic scaling in the general dental service in Scotland [ISRCTN99609795].

BACKGROUND: To investigate, within general dental practice, patients' and vocational dental practitioners' (VDP) attitudes towards the benefits and costs of a simple scale and polish and to compare the experience of using manual versus ultrasonic instruments to scale teeth. METHODS: 28 VDPs and 420 patients participated. Patients were randomly allocated to either group. Patients' and VDPs' attitudes towards, and experience of, the scale and polish were elicited by means of self-administered questionnaires. RESULTS: The majority of patients (99%) believed a scale and polish was beneficial. VDPs considered ultrasonic treatment to be appropriate on significantly more occasions than they did for manual scale and polish (P < 0.001). Patient discomfort: with ultrasonic scaling 69.2% felt 'a little uncomfortable' or worse compared with 60% of those undergoing manual treatment (P = 0.072). VDPs considered treatment charges were appropriate for 77% of patients. CONCLUSION: Routine scaling and polishing is considered beneficial by both patients and vocational trainees. The majority of patients, regardless of treatment method, experience some degree of discomfort when undergoing a scale and polish. VDPs showed a preference for the ultrasonic treatment method.

Journal Article↗

PubMed1998

Ultrasonic evaluation of ultra-high molecular weight polyethylene used in medical prostheses.

An ultrasonic non-destructive evaluation process is established to observe cracks and delaminations that occur below the surface of retrieved ultra-high molecular weight polyethylene joints. The result from the ultrasonic evaluation is compared with destructive (optical) test results of the actual cracks. Feasibility of characterizing different grades of bulk polyethylene is also established by means of ultrasonic attenuation measurements in the materials. This ultrasonic data can be used to give a better understanding of the failure mechanisms in the UHMWPE material.

Humans↗

PubMed1985

Excision biopsy of the spleen by ultrasonic guidance.

Excision biopsy of the spleen was performed in 32 patients, using a recently invented instrument, which consists of a spring-trigger system for firing the two parts of a Tru-Cut needle. The biopsies were carried out under the guidance of an ultrasonic scanner. This technique yields sufficient material of high quality for a proper evaluation both of individual cells and the internal structure of the spleen. Eight patients had parenchymal abnormalities found by ultrasonic scanning: five had multiple abnormalities whereas three had a single abnormal area. Seven of these eight patients had a pathological spleen biopsy, consisting of Hodgkin's disease (four patients), "high-grade" malignant non-Hodgkin's lymphoma (two patients) or tuberculosis (one patient). In the other 24 patients with a normal ultrasonic picture of the splenic parenchyma five biopsies were pathological (3 cases of hairy-cell leukaemia, 1 of Gaucher's disease and 1 of Hodgkin's disease). Side-effects were: slight to moderate pain (16/32 patients) and bleeding requiring transfusion (4/32 patients). In one of these patients splenectomy was performed because of the bleeding. Two of the patients with bleeding complications suffered from hairy-cell leukaemia. It is concluded from this study that excision biopsy of the spleen is a diagnostic method which in some patients can replace splenectomy. The method seems to be valuable especially in patients with parenchymal abnormalities shown by ultrasonic scanning.

Adolescent↗

PubMed1993

Needle aspiration biopsy of malignant lung masses with necrotic centers. Improved sensitivity with ultrasonic guidance.

False-negative results from transthoracic needle aspiration biopsy of malignant lung masses may occur if a central necrotic area is present and is the source of the biopsy material. The purpose of this study is to determine if the use of ultrasonic guidance can improve the sensitivity of lung needle biopsies in this circumstance. Sixty patients with malignant lung masses underwent ultrasonic examination in an 18-month period. In 14 cases, ultrasound showed that the mass had a large central necrotic area that was at least half the diameter of the tumor. Under ultrasonic guidance, needle biopsy specimens were taken from the central necrotic area and from the tumor wall in each case. Adequate biopsy specimens were obtained in all 14 patients. In all cases, the mural biopsy material was diagnostic for malignant tumor, while the biopsy specimen from the necrotic center was nondiagnostic in 10 of 14 patients. No complications occurred. We conclude that ultrasonically guided lung biopsy is a useful and safe tool to avoid false-negative needle biopsy specimens in malignant lung tumors with necrotic centers.

Adenocarcinoma↗

PubMed1986

Comparison of bronchial responses to ultrasonically nebulized distilled water, exercise, and methacholine in asthma.

We compared the responses to inhaled methacholine, ultrasonically nebulized distilled water, and exercise in 25 subjects with atopic asthma. The methacholine inhalation test and challenges with distilled water and exercise were performed on three separate days 48 hours apart. Bronchial responsiveness to methacholine and ultrasonically nebulized distilled water was measured as the concentration of methacholine (PC20M) and the volume output of the ultrasonic nebulizer (PO20 UNDW) producing a 20 percent fall in the forced expiratory volume in one second (FEV1). The response to exercise was expressed as the percentage of fall in FEV1 from the value before exercise. Seventeen subjects showed a fall in FEV1 of more than 20 percent after exercise. Eight subjects had a stimulus-response curve to distilled water that was flat up to the maximal volume output from the nebulizer, but only four of them also showed no significant response to exercise. The response to exercise correlated better with PO20 UNDW (r = -0.66; p less than 0.01) than with PC20M (r = -0.19; p greater than 0.5) in those responding to distilled water. In all of the tested subjects, exercise-induced bronchoconstriction correlated with PC20M (r = -0.61; p less than 0.01). The mean PC20M was significantly lower in the subjects with a significant response to distilled water and exercise (p less than 0.001 and p less than 0.0001, respectively). We concluded that ultrasonically nebulized distilled water and exercise provoke significant bronchoconstriction in the subjects with more severe nonspecific bronchial hyperresponsiveness. The correlation found between the two stimuli supports the hypothesis that they act by similar mechanisms.

Adolescent↗

PubMed1989

Development of an ultrasonic system for three-dimensional reconstruction of the fetus.

The ultrasonic diagnostic devices available at present can only represent one section of the fetus. We have developed a system for three-dimensional reconstruction of the ultrasonic fetal image in order to facilitate the understanding of the 3-D structure of the fetus and also to make 3-D recordings of this image. Either a real-time linear array probe or a convex array probe of the ultrasonic scanner was mounted on a position sensing arm of a manual compound scanner in order to detect the position of the probe. A microcomputer was used to convert the positional information to a recording of a visual image of videotape. This image was superimposed onto the ultrasonic tomographic image simultaneously using a superimposer and was recorded on the video tape, thereafter, being recalled by the image processing minicomputer. The minicomputer VAX11/780 (DEC) system was used for 3-D reconstruction and 3-D display. In the memory system the image of the anterior uterine wall was identified and subsequently excluded in order to visualise the fetus more clearly. The threshold of brightness was set to a high level so that the fetus could be separated from the amniotic fluid. The fetus was displayed three-dimensionally using computer graphics. Using this system, we have made it possible to observe the whole image of the fetus in utero non-invasively. This system offers a method for easier understanding of the 3-D structure of the fetus in utero and also makes 3-D recording possible. In the future, we confidently expect that this system will be used for screening for fetal anomalies and abnormalities of fetal growth.

Equipment Design↗