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Biomedical subjects

J G Miller

Publications and source records attributed to J G Miller.

At least 19 recordsLinked to original sources
PubMed1992

Automated, on-line quantification of left ventricular dimensions and function by echocardiography with backscatter imaging and lateral gain compensation.

To provide on-line quantification of left ventricular cavity dimensions and function by echocardiography 60 control subjects and 10 patients with cardiac dysfunction were studied. A novel, ultrasound imaging system was used which was developed to detect and track, in real time, ventricular endocardial blood boundaries based on quantitative assessment of acoustic properties of tissue. In addition, lateral gain compensation, a robust and novel image enhancement procedure, was used to provide instantaneous measurement and display of cavity areas and functional indexes on a beat-by-beat basis within regions of interest drawn around the blood pool cavity. In control subjects, short-axis end-diastolic area averaged 13.1 +/- 3.7 cm2 (SD), end-systolic area 5.9 +/- 2.7 cm2, and fractional area change 55.6 +/- 11.2%. Apical views yielded corresponding values of 23.8 +/- 4.5 cm2, 15.5 +/- 3.4 cm2 and 34.7 +/- 7.8%. Instantaneous peak rate of cavity area change approximated 50 cm2/s in systole and 60 cm2/s in diastole in each view. Serial measurements of area and functional index were reproducible over intervals of 2 to 3 weeks. Patients with dilated ventricles exhibited average apical view area values of 49.1 +/- 6.1 cm2 and 43.1 +/- 4.9 cm2 in diastole and systole with a fractional area change of 12.2 +/- 3.0%. Thus, results with on-line echocardiographic backscatter imaging-assisted automated edge detection are reproducible and capable of delineating cardiac dysfunction conveniently, promptly and serially at the bedside.

Adult↗
PubMed1992

Quantitative ultrasonic imaging: tissue characterization and instantaneous quantification of cardiac function.

Quantitative myocardial tissue characterization is being developed to complement and expand conventional echocardiography by delineating the physical state of myocardium under diverse pathophysiologic conditions. Real-time quantitative integrated backscatter imaging has already been applied to patients with ischemic heart disease, hypertrophic cardiomyopathy, and cardiac allograft rejection in clinical investigations performed in the United States, Europe, and Japan. A recently introduced modification of imaging processing algorithms employed for characterization of tissue facilitates automatic detection of endocardial-blood interfaces and on-line quantification of ventricular size and function. Further progress and anticipated developments in quantitative ultrasonic imaging will undoubtedly augment the clinical applications of tissue characterizations based on myocardial integrated backscatter for improved diagnosis, elucidation of pathophysiology, and assessment of cardiac function.

Animals↗
PubMed1992

Long term follow-up of a case of Kasabach-Merritt syndrome successfully treated with radiotherapy and corticosteroids.

Kasabach-Merritt syndrome is the association of thrombocytopenia, spontaneous bleeding, and enlargement of a haemangioma. It is caused by an intense, self-perpetuating process of clot-formation and lysis within the abnormal vascular channels of the haemangioma, and results in consumption of platelets and clotting factors. Treatment involves ablation of the lesion with or without pharmacological manipulation of the coagulation and fibrinolytic systems. No single therapeutic modality is universally successful but a combination of radiotherapy and corticosteroids can result in a dramatic, immediate response with minimal long term complications.

Adrenal Cortex Hormones↗
PubMed1992

Differentiation of normal and ischemic right ventricular myocardium with quantitative two-dimensional integrated backscatter imaging.

We have previously shown that ultrasonic tissue characterization with two-dimensional (2D) guided M-Mode acquisition of integrated backscatter (IB) identifies ischemic and infarcted myocardium. However, there is no information regarding the applicability of IB in assessment of right ventricular (RV) myocardial acoustic properties. Thus, we performed IB imaging of the RV in a group of 45 consecutive patients and were successful in 16, all of whom had normal RV wall motion. This group was compared to 8 additional patients studied acutely with clinical criteria of RV infarction. Real-time IB from RV was obtained from parasternal long axis or subcostal views. Diastolic-to-systolic cyclic variation of IB in normals was 4.8 +/- 0.9 dB (+/- SD). No significant difference was observed between parasternal and subcostal views (5.2 +/- 0.8 and 4.5 +/- 0.9 dB). Mean value of delay (R wave to nadir of backscatter normalized to the electrocardiographic Q-T interval) was 0.85 +/- 0.07. Patients with RV infarction had significantly lower values averaging 3.2 +/- 0.8 dB (p less than 0.001 vs. normals); cyclic variation of IB was present in all despite severe hypokinesis in 4/8. Mean value of normalized delay was 0.80 +/- 0.04 and was not different from normals. Thus, tissue characterization provides quantitative information regarding RV myocardial structure and function. Preservation of IB cyclic variation in patients with RV infarction suggests residual RV myocardial viability.

Coronary Disease↗
PubMed1992

An algorithmic approach to the management of cutaneous burns.

An algorithm of fluid resuscitation for cutaneous burns is presented. The management of these cases entails an initial process of evaluation followed, when appropriate, by the administration of intravenous fluids. The fluid requirements are prospectively calculated and subsequently modified by using closed loop feedback with monitoring of urine output, plasma deficit, osmolality and vital signs. Three 'problem boxes' have been incorporated into the algorithm to outline the management of: 1. fluid deficit and excess; 2. acute renal failure; 3. the critically ill patient. An algorithm such as this can never be complete, but in its present form it provides both a teaching tool for junior staff as well as a valuable clinical aid for those involved in the acute management of burns patients.

Algorithms↗
PubMed1992

Abnormal myocardial acoustic properties in diabetic patients and their correlation with the severity of disease.

Although patients with diabetes mellitus may be afflicted by cardiomyopathy, its prevalence and nature are controversial. Studies have shown that fibrosis alters the acoustic properties of the heart in animals and humans and that the changes are detectable by cardiac tissue characterization with ultrasound. The present study was performed to characterize myocardial acoustic properties in patients with insulin-dependent diabetes to determine whether ultrasound tissue characterization could detect changes potentially indicative of occult cardiomyopathy. The magnitude of cyclic variation of myocardial ultrasound integrated backscatter and its phase delay with respect to the onset of the cardiac cycle in the septum and posterior wall of the left ventricle were measured in 54 patients with diabetes who had no overt cardiac disease. Conventional echocardiography documented normal ventricular systolic function in 96%. As compared with results in age-matched patients without diabetes studied previously, cyclic variation of integrated backscatter was reduced (4.6 +/- 0.8 vs. 3.6 +/- 1.4 dB; p less than 0.001). In addition, delay was significantly increased (0.86 +/- 0.09 vs. 0.99 +/- 0.15). The primary analysis of the data focused on differences among the diabetic patients. Reduction of cyclic variation of backscatter was greatest in patients with diabetes who had neuropathy (3.2 +/- 1.0 dB; p less than 0.001) as was the increase in delay (1.04 +/- 0.16, p less than 0.001 vs. values in patients without neuropathy). Retinopathy and nephropathy were associated with abnormal myocardial acoustic properties as well. Thus, abnormalities that may reflect fibrosis or other occult cardiomyopathic changes in diabetic patients without overt heart disease are readily detectable by myocardial tissue characterization with ultrasound and parallel the severity of noncardiac diabetic complications.

Cardiomyopathies↗
PubMed1992

On-line assessment of ventricular function by automatic boundary detection and ultrasonic backscatter imaging.

To provide an approach suitable for on-line analysis of ventricular function, a conventional two-dimensional ultrasound imaging system was modified to detect and track blood-tissue interfaces in real time based on their quantitative acoustic properties. This modification permitted on-line display of the left ventricular cavity area, fractional area change, volumes and ejection fraction on a beat by beat basis. Images were obtained from 54 patients and 12 normal subjects with broad ranges of ventricular dimensions and systolic function. On-line measurements of cavity areas were compared with off-line measurements of cavity areas (analysis of videotaped conventional images). Left ventricular cavity areas measured on-line from short-axis views correlated closely with off-line views as did areas from apical views. On-line fractional area change correlated well with ejection fraction calculated off-line. More than 70% of patients could be studied adequately with the approach developed. Thus, automatic boundary detection based on quantitative assessment of tissue acoustic properties permits on-line quantitation of ventricular cavity areas and indexes of function.

Algorithms↗
PubMed1992

Culture and moral judgment: how are conflicts between justice and interpersonal responsibilities resolved?

A 2-session study examined Indian and American adults' and children's (N = 140) reasoning about moral dilemmas involving conflicts between interpersonal and justice expectations. Most Indians gave priority to the interpersonal expectations, whereas most Americans gave priority to the justice expectations. Indians tended to categorize their conflict resolutions in moral terms. In contrast, when Americans gave priority to the interpersonal alternatives, they tended to categorize their resolutions in personal terms. Results imply that Indians possess a postconventional moral code in which interpersonal responsibilities are seen in as fully principled terms as justice obligations and may be accorded precedence over justice obligations. Findings also suggest that a personal morality of interpersonal responsiveness and caring is linked to highly rights-oriented cultural views, such as those emphasized in the United States.

Adolescent↗
PubMed1992

On-line quantification of ventricular function during dobutamine stress echocardiography.

To develop an approach for on-line quantification of left ventricular size and function during pharmacological stress testing we employed echocardiographic automatic edge detection via integrated backscatter imaging during dobutamine infusion in 27 patients. Ventricular cavity areas, fractional area change and rate of cavity area change were obtained on-line with instantaneous graphic display of the data. When compared to baseline image data, patients with a normal response exhibited modest (15%) reduction in end-diastolic cavity areas at peak dobutamine level, but marked (33%) reduction in systolic areas yielding a 52% increase in fractional area change (n = 13; P < 0.001). The second group of patients (n = 14) had an abnormal response characterized by limited changes in measured parameters of ventricular function and reduced fractional area change (P < 0.05). On-line quantification during pharmacological stress echocardiography is a promising addition to the test for surveillance and objective instantaneous evaluation of global cardiac responses.

Adult↗
PubMed1992

Identification of human myocardial infarction in vitro based on the frequency dependence of ultrasonic backscatter.

It has been reported previously that acute and mature myocardial infarction in dogs can be differentiated in vitro and in vivo by ultrasonic tissue characterization based on measurement of the frequency dependence of ultrasonic backscatter. To characterize human infarction with an index of the frequency dependence of backscatter that could be obtained in patients, cylindrical biopsy specimens from 7 normal regions and 12 regions of infarction of 6 fixed, explanted human hearts in 2-deg steps around their entire circumference with a 5-MHz broadband transducer were insonified. One to six consecutive transmural levels were studied for each specimen. The dependence of apparent (uncompensated for attenuation or beam width) backscatter, /B(f)/2, on frequency (f) was computed from spectral analyses of radio-frequency data as /B(f)/2 = afn, where from theoretical considerations the magnitude of n decreases as scatterer size increases. Apparent integrated backscatter was computed as the average of /B(f)/2 from 3 to 7 MHz. The average value for n for normal tissue (0.9 +/- 0.1) exceeded that for tissue from regions of infarction (0.6 +/- 0.1; p less than 0.05). Infarct manifested a significant decrease of n from epicardial to endocardial levels (epi----mid----endo: 0.9----0.7----0.2; p less than 0.05) whereas normal tissue manifested similar values for n at each transmural level (0.8----1.1----0.9; p = NS). Average integrated backscatter across all transmural levels for infarct was significantly greater than for normal tissue (-48.3 +/- 0.5 vs -53.4 +/- 0.4 dB, infarct versus normal; p less than 0.05). The presence of fibrosis was associated with smaller values of n and greater integrated backscatter.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed1992

Anisotropy of ultrasonic velocity and elastic properties in normal human myocardium.

Measurements of ultrasonic quasilongitudinal velocity were made in the muscle fiber plane of excised human myocardium. Multiple adjacent planes across the left ventricular wall were interrogated to assess the transmural dependence of velocity. For each measurement plane, data were obtained in 2-deg increments through the full 360 deg relative to the myofibers. An approximate 1.3% magnitude of anisotropy was observed with maximum velocity along the muscle fibers and minimum velocity perpendicular to the muscle fibers. The known transmural shift in myofiber orientation was evidenced in the anisotropy of velocity as angular shifts between plots obtained from adjacent transmural planes within the same specimen. Measured values of velocity and density were used to estimate the effective C33 and C11 elastic constants of a thin layer of normal myocardium.

Anisotropy↗
PubMed1992

Quantification of atherosclerotic plaque composition in cholesterol-fed rabbits with 50-MHz acoustic microscopy.

To determine whether high-frequency ultrasound could distinguish normal from pathological vascular structure and to elucidate the determinants of ultrasonic backscatter in different layers of normal and atherosclerotic arteries, high-resolution acoustic microscopy at 50 MHz was used to characterize aortic plaque in six New Zealand White rabbits fed a 2% cholesterol diet for 3.5 months. Four rabbits were fed a standard diet for 3.5 months to provide normal control data. Segments of aortas were excised, fixed in formalin, opened longitudinally, and mounted flat for insonification. For each specimen, backscattered radio frequency (rf) data were acquired from 30 to 100 independent sites separated by 500 microns. Portions of rf data were gated from discrete layers of the vessel wall for computation of integrated backscatter. Results of histological and immunocytochemical analyses of vessel wall thickness and composition were compared with those of ultrasonic analysis. Normal aortas manifested prominent but homogeneous backscatter (average integrated backscatter, -28.5 +/- 2.9 dB) throughout the vessel wall, with no clear distinction between intimal and medial layers. The atherosclerotic aortas manifested substantially reduced integrated backscatter from the thickened intima (-47.5 +/- 3.2 dB, p < 0.0001) but relatively normal integrated backscatter from the media (-31.2 +/- 1.6 dB; p = NS versus normal aortas). The thickness of the media for both normal and atherosclerotic rabbits was approximately 300 microns. Histological characteristics of atherosclerotic aortas confirmed the presence of substantial intimal thickening, with prominent foam cell and lipid infiltration abutting a more normal medial layer.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
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↗
PubMed1992

Detection of unique transmural architecture of human idiopathic cardiomyopathy by ultrasonic tissue characterization.

BACKGROUND: Noninvasive approaches to the evaluation of idiopathic cardiomyopathy are limited. Recent work from our laboratory has used quantitative ultrasound to define the three-dimensional structure of normal human myocardium and the myocardial remodeling associated with infarction. Our goal was to define the role of ultrasonic tissue characterization for detection of specific alterations in the three-dimensional transmural architecture of idiopathic dilated cardiomyopathy. METHODS AND RESULTS: We measured frequency-dependent backscatter from 22 cylindrical biopsy specimens from nine explanted fixed hearts of patients who underwent heart transplantation for idiopathic cardiomyopathy, seven specimens from normal portions, and 12 specimens of infarcted tissue from six explanted fixed human hearts. Consecutive transmural levels from each specimen were insonified with a 5-MHz broadband transducer. The dependence of apparent (uncompensated for attenuation) backscatter, B(f), on frequency (f) was computed from radiofrequency (rf) data as: magnitude of B(f)2 = afn, where n is an index that reflects in part the size of the dominant scatterers in myocardial tissue. Myofiber diameter and percentage fibrosis were determined at each transmural level for each specimen. For cardiomyopathic tissue, the frequency dependence of backscatter (n) increased progressively from epicardial to endocardial (0.02 +/- 0.37 to 1.01 +/- 0.12, p less than 0.05) levels in conjunction with a progressive decrease in myofiber diameter (29.5 +/- 0.9 to 21.4 +/- 0.6 microns, p less than 0.0001). In contrast, in tissue from areas of infarction, the frequency dependence decreased progressively from epicardium to endocardium (0.91 +/- 0.20 to 0.23 +/- 0.21, p less than 0.05) in conjunction with a progressive increase in the percentage of fibrosis (23.5 +/- 9.4% to 54.5 +/- 4.9%, p less than 0.005). Normal tissue exhibited no significant transmural trend for frequency dependence, myofiber diameter, or percentage fibrosis. CONCLUSIONS: These data indicate the presence of a heterogenous transmural distribution of scattering structures associated with human idiopathic cardiomyopathy and myocardial infarction that may be detected by ultrasonic tissue characterization. The divergence of these transmural trends for frequency dependence of backscatter reflects distinct mechanisms of structural heterogeneity for different pathological processes that comprise a transmural gradation of cell size and fibrosis for idiopathic cardiomyopathy and infarction, respectively.

Cardiomyopathies↗
PubMed1992

ATLAS-plus: multimedia instruction in embryology, gross anatomy, and histology.

ATLAS-plus [Advanced Tools for Learning Anatomical Structure] is a multimedia program used to assist in the teaching of anatomy at the University of Michigan Medical School. ATLAS-plus contains three courses: Histology, Embryology, and Gross Anatomy. In addition to the three courses, a glossary containing terms from the three courses is available. All three courses and the glossary are accessible in the ATLAS-plus environment. The ATLAS-plus environment provides a consistent set of tools and options so that the user can navigate easily and intelligently in and between the various courses and modules in the ATLAS-plus world. The program is a collaboration between anatomy and cell biology faculty, medical students, graphic artists, systems analysts, and instructional designers.

Anatomy↗
PubMed1992

On mitigating professional arrogance in the treatment of sex offenders.

This article suggests that the adversarial approach of the criminal justice system towards handling of the paraphilias ultimately does more harm than good. The acceptance by helping professionals of the criminal justice model into their diagnostic consideration and treatment procedures is discussed, along with a discussion of some of the debilitating ethical and scientific implications of such an alignment. Historical, political and professional factors which have contributed to these disturbing trends are discussed and proposals are made as to how helping professionals might reclaim and reassert their traditional roles in service of their clientele.

Attitude↗
PubMed1991

A living systems analysis of organizational pathology.

Organizations have essentially the same subsystem processes as living systems at other levels. All of them adjust subsystem variables to changing environmental and internal circumstances. Pathology exists in any system when a subsystem variable remains out of its steady-state range for an extended period. The same classes of pathology can be found at all levels. This article analyzes the various forms of pathology that exist in living systems at the level of organizations and describes living systems process analysis. Studies of several types of organizations including U.S. Army battalions, a corporation, a hospital, and a possible space station or lunar base, are discussed.

Animals↗