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Biomedical subjects

H E Melton

Publications and source records attributed to H E Melton.

5 recordsLinked to original sources
PubMed1992

Reproducibility of quantitative backscatter echocardiographic imaging in normal subjects.

Cyclic backscatter variation is useful in differentiating normal from ischemic and myopathic myocardium; however, there are few data on the reproducibility of clinical cyclic variation measurements. Therefore, a study using 2-dimensional and M-mode backscatter imaging was performed in 20 normal male subjects by 2 observers at an initial session and by 1 of the observers after 1 week. Cyclic variation on M-mode was calculated as the difference between the end-diastolic backscatter and the backscatter at the nadir. Two-dimensional determinations of backscatter were made using a single frame at end-diastole and one at end-systole. The cyclic change was the difference between backscatter measured in the end-diastolic and end-systolic frames. There were no statistically significant differences in analysis of variance among the grouped repeated measurements in either the interventricular septum or the posterior left ventricular wall. At the initial session, cyclic backscatter variation in the posterior wall using M-mode techniques was 5.9 +/- 1.8 dB (SD). The cyclic change in backscatter in the septal wall, using the 2-dimensional technique, was 4.3 +/- 2.4 dB. In the posterior wall, the cyclic change in backscatter was 5.7 +/- 1.7 dB. Pairwise observer correlations between repeated measurements ranged from -0.48 to 0.45. Thus, although there were no significant differences in group means on repeat measurements, repeated measurements in individual subjects were not reliably reproduced because of limited independent sampling of backscatter measurements at only 2 points in the heart cycle. Increased independent sampling and measurement from a backscatter waveform throughout the cardiac cycle may improve reproducibility of measurements.

Adult↗
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

Estimation of left ventricular cavity area with an on-line, semiautomated echocardiographic edge detection system.

BACKGROUND: Automated edge detection of endocardial borders in echocardiograms provides objective, reproducible estimation of cavity area; however, most methods have required off-line analysis. A recently developed prototype echocardiographic imaging system permits real-time automated edge detection during imaging and thus, the potential for measurement of cyclic changes in cavity area and the assessment of left ventricular function on-line. Our purpose was to compare measurements of endocardial area manually traced from conventional echocardiograms with those obtained with the real-time automated edge detection system in normal subjects. METHODS AND RESULTS: Two training sets of images were used to establish optimal methods of gain setting; the settings were then evaluated in a test set of images. In the high-gain training group (n = 8 subjects, 119 images), gain settings were adjusted sufficiently high to display at least 90% of the endocardial border. Manually drawn and real-time area measurements correlated at r = 0.92, but manually drawn areas were underestimated by computer. In the low-gain training group (n = 7 subjects, 104 images), gain settings were adjusted sufficiently low to avoid cavity clutter despite the presence of dropout of endocardial edges. Manually drawn and real-time areas again correlated (r = 0.79), but manually drawn areas were overestimated by computer. In the intermediate-gain test group (n = 7 subjects, 105 images), gain settings were balanced between maximal endocardial definition (greater than or equal to 90%) and minimal cavity clutter (less than or equal to 1 cm2). Manually drawn and real-time areas correlated at r = 0.91 for the group, and r ranged from 0.94 to 0.99 in individual subjects. Interobserver variability was 9.5% for manually traced areas and 10.6% for real-time area measurements. CONCLUSIONS: Real-time on-line automated edge detection provides accurate estimation of manually drawn cavity areas. Although the method is gain dependent, measurements are reproducible. The system should have clinical application in settings in which measurements of left ventricular function are important.

Adult↗
PubMedDate not supplied

Diagnosis of recent myocardial infarction with quantitative backscatter imaging: preliminary studies.

Acute myocardial ischemia and chronic myocardial infarction may be recognized with ultrasound tissue characterization techniques because of myocardial acoustic changes caused by reduced perfusion and/or collagen deposition. Our purpose was to study the acoustic properties of recent myocardial infarction when the predominating pathologic finding was myocardial edema and leukocytic infiltration. We used a new quantitative backscatter imaging system to study 18 patients 9 +/- 5 days after myocardial infarction (eight patients with anteroseptal myocardial infarction and 10 with inferior myocardial infarction) and 20 normal subjects. The cyclic variation of relative integrated backscatter (end-diastolic minus end-systolic) was calculated from on-line measurements. Standard parasternal long- and short-axis and apical four- and two-chamber views were obtained. In the anteroseptal myocardial infarction group, the cyclic variation of relative integrated backscatter was lower in the septum (1.5 +/- 1.6 dB) than in the posteroinferior wall (3.2 +/- 1.2 dB); however, the sample size of only three patients (of eight patients imaged) in the latter group prevented statistical comparison. The cyclic variation of relative integrated backscatter in the infarcted septum was less than the measurement obtained in the septum of the control group (4.3 +/- 2.4 dB, p less than 0.05). In the inferior infarction group, the cyclic variation of integrated backscatter in the posteroinferior wall (1.8 +/- 1.7 dB) was not significantly different from the measurement obtained in the septum (3.7 +/- 3.6 dB); however, the cyclic variation in the posteroinferior wall was significantly less than that obtained in the control group posteroinferior wall (5.7 +/- 1.7 dB, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Angiography↗