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W R Janowitz

Publications and source records attributed to W R Janowitz.

At least 19 recordsLinked to original sources
PubMed2001

Current status of mechanical computed tomography in cardiac imaging.

Mechanical computed tomography (CT) scanners have undergone significant improvements in their ability to perform cardiac imaging. Previously limited by cardiac motion artifacts and slow acquisition speeds, newer-generation scanners are able to obtain multiple slices with a temporal resolution of <100 msec, minimizing motion artifacts to levels comparable to electron-beam computed tomography (EBCT). This is done using various approaches, including (1) prospective and retrospective electrocardiographic gating, (2) multislice detectors, and (3) partial and segmented reconstruction algorithms. The major CT manufacturers are putting significant resources into protocol optimization and cardiac applications development, including coronary calcium quantification, functional analysis, and coronary CT angiography. Given the rapid pace of development, higher in-plane and z-axis spatial resolution, and superior signal-to-noise ratio of mechanical scanners, it is evident that they will be capable of performing cardiac imaging with a quality approaching or possibly surpassing that of existing EBCT scanners. This article summarizes the current status of mechanical CT scanners in cardiac imaging.

Equipment Design↗
PubMed2001

CT imaging of coronary artery calcium as an indicator of atherosclerotic disease: an overview.

Quantification of coronary artery calcium by computed tomography is used to detect coronary atherosclerosis in both symptomatic and asymptomatic individuals. It correlates with the extent of atherosclerosis in individuals with obstructive and nonobstructive coronary artery disease. It is unique among the various noninvasive techniques available to assess coronary artery disease, which typically depend on the presence of flow-limiting lesions. It appears to be a better predictor of risk of future events than conventional risk factors because it is anatomical evidence of subclinical disease. To best use this technology, an understanding of the pathologic principles underlying coronary artery calcification and new concepts in the theory of atherosclerosis progression are necessary. These concepts are true whether helical or electron beam computed tomography is used to quantitate coronary artery calcium.

Calcinosis↗
PubMed1997

Coronary arteries: retrospective cardiac gating technique to reduce cardiac motion artifact at spiral CT.

Coronary artery calcification is a marker of atherosclerosis. Detection and quantification has previously been accomplished with electron-beam computed tomography (CT). Use of spiral CT for this application has been limited by cardiac motion. The authors evaluated a retrospective cardiac-gated postprocessing technique that necessitates no modification of scanner hardware or software. At spiral CT in 26 patients, motion artifact was reduced, coronary arteries were consistently visualized, and quantification of calcification could be performed in those patients with prominent deposits. Coronary artery calcification screening can therefore be offered in sites that have access to only spiral CT.

Algorithms↗
PubMed1996

Ultrafast computed tomography as a diagnostic modality in the detection of coronary artery disease: a multicenter study.

BACKGROUND: Ultrafast computed tomography (CT), by acquiring images of the proximal coronary arteries, detects coronary calcifications and has been demonstrated to be highly sensitive for the detection of coronary artery disease in many small studies. The aim of this study was to determine the relationship between ultrafast CT scanning and coronary angiography in a large number of symptomatic patients. METHODS AND RESULTS: The study population consisted of 710 patients from six participating centers. A multivariate logistic regression model was used to evaluate the individual contributions of age, number of calcified vessels, and the calcium score for the probability of angiographically significant disease. Of the 710 patients enrolled, 427 patients had significant angiographic disease, and coronary calcification was detected in 404, yielding a sensitivity of 95%. Of the 23 patients without calcifications, 19 (83%) had single-vessel disease at angiography. Of the 283 patients without angiographically significant disease, 124 had negative ultrafast CT coronary studies, for a specificity of 44%. An increasing number of vessels with calcification present on ultrafast CT was found to increase specificity for the presence of obstructive coronary artery disease in at least one vessel (P < .0001). As the log of the calcium score increases, the probability of multivessel obstructive disease increases (P < .0001). CONCLUSIONS: Ultrafast CT scanning is an noninvasive, non-exercise-dependent test with an excellent sensitivity for the detection of coronary artery disease. The presence of calcifications in multiple vessels and in younger populations correlates with higher specificities for obstructive disease, making ultrafast CT coronary scanning a very useful diagnostic test.

Adult↗
PubMed1993

Differences in prevalence and extent of coronary artery calcium detected by ultrafast computed tomography in asymptomatic men and women.

Coronary artery calcium is a marker of atherosclerosis in asymptomatic subjects. Ultrafast computed tomography (CT) can detect and quantify coronary calcium, simply and noninvasively, with greater sensitivity than can other techniques. The prevalence and extent of coronary calcium in a large population of asymptomatic men and women were measured and compared. Coronary calcium studies were performed in an asymptomatic population of 1,396 male and 502 female subjects (age range 14 to 88 years). The prevalence of calcium, and the distribution of total calcium scores (which reflect the amount of calcium present) were determined and compared for men and women at 5- and 10-year intervals. The prevalence of calcium in women was half that of men, until the age of 60 years when the difference diminished. The mean total calcium score distributions of men between the ages of 40 and 69 years were virtually identical to those of women between the ages of 50 and 79. The quantitative data obtained by Ultrafast CT showed very close agreement with autopsy studies of coronary calcium. Ultrafast CT is a sensitive technique to measure coronary calcium in both men and women. The differences in prevalence and extent of coronary calcium appear to be parallel to those observed in the clinical incidence of coronary artery disease in men and women. Ultrafast CT may have a greater impact on the treatment of women than of men, because it can be used to provide objective evidence of coronary atherosclerosis.

Adolescent↗
PubMed1993

Coronary artery diameter and coronary risk factors: a study with ultrafast computed tomography.

Coronary artery dilation has been described as an early effect of atherosclerosis. No noninvasive technique has been available to measure coronary size. In this study coronary diameters were measured in 100 asymptomatic subjects (89 men and 11 women, mean age 40 +/- 6 years) by means of ultrafast computed tomography (UFCT), with 3 mm thick ECG gated scans. Subjects without evidence of coronary calcium were studied. The diameter of the left main (LD) and right (RD) coronary arteries were measured. Total coronary diameter, TD = LD + RD, was determined, and univariate analysis was performed with respect to total, high-density lipoprotein and low-density lipoprotein cholesterol, mean blood pressure, age, body surface area, and triglycerides. Mean LD was 4.23 +/- 0.85 mm, and mean RD was 3.06 +/- 1.08 mm. TD increased with body surface area (p < 0.001). No other variable showed any significant effect on TD in this group without evidence of atherosclerosis. UFCT can be used to noninvasively measure coronary artery diameters and may be a useful technique to detect early changes of atherosclerosis in individual patients and in population studies.

Adult↗
PubMed1991

Comparison of serial quantitative evaluation of calcified coronary artery plaque by ultrafast computed tomography in persons with and without obstructive coronary artery disease.

Coronary artery calcium indicates atherosclerosis. Ultrafast computed tomography (CT) can noninvasively visualize and quantify coronary calcium, permitting the natural history of calcified plaque to be studied. This pilot study evaluates the ability of ultrafast CT to follow the progression of calcified plaque within the coronary arteries in patients with and without obstructive coronary artery disease (CAD). Twenty-five subjects had serial ultrafast CT scans of the coronary arteries a mean of 406 days apart. Changes in the number of calcific deposits, calcified plaque area and volume, calcium density and total calcium score were measured. In the 20 patients with calcium on the first study, there were statistically significant increases in mean peak CT number, total calcified plaque volume, total calcified plaque area and total calcium score (p less than 0.0001 for all). Subjects with proved obstructive CAD (n = 10) on angiography had a 48% increase in calcified plaque volume compared with 22% in asymptomatic subjects (n = 10). Comparison of serial studies showed that smaller calcific deposits often coalesced into single larger calcific deposits. Ninety-eight percent (235 of 241) of deposits identified on the first study were accounted for on the second study. Patients with obstructive CAD had a higher number of new calcific deposits than did those in the asymptomatic group (55 vs 18, p = 0.058). Serial ultrafast CT accurately tracks the progression of coronary artery calcium. It is a useful technique for assessing changes in calcified plaque formation in both asymptomatic subjects and in patients with obstructive CAD. It may be useful for studying the natural history of CAD and the effects of intervention on the course of CAD.

Adult↗
PubMed1990

Quantification of coronary artery calcium using ultrafast computed tomography.

Ultrafast computed tomography was used to detect and quantify coronary artery calcium levels in 584 subjects (mean age 48 +/- 10 years) with (n = 109) and without (n = 475) clinical coronary artery disease. Fifty patients who underwent fluoroscopy and ultrafast computed tomography were also evaluated. Twenty contiguous 3 mm slices were obtained of the proximal coronary arteries. Total calcium scores were calculated based on the number, areas and peak Hounsfield computed tomographic numbers of the calcific lesions detected. In 88 subjects scored by two readers independently, interobserver agreement was excellent with identical total scores obtained in 70. Ultrafast computed tomography was more sensitive than fluoroscopy, detecting coronary calcium in 90% versus 52% of patients. There were significant differences (p less than 0.0001) in mean total calcium scores for those with versus those without clinical coronary artery disease by decade: 5 versus 132, age 30 to 39 years; 27 versus 291, age 40 to 49 years; 83 versus 462, age 50 to 59 years; and 187 versus 786, age 60 to 69 years. Sensitivity, specificity and predictive values for clinical coronary artery disease were calculated for several total calcium scores in each decade. For age groups 40 to 49 and 50 to 59 years, a total score of 50 resulted in a sensitivity of 71% and 74% and a specificity of 91% and 70%, respectively. For age group 60 to 69 years, a total score of 300 gave a sensitivity of 74% and a specificity of 81%. The negative predictive value of a 0 score was 98%, 94% and 100% for age groups 40 to 49, 50 to 59 and 60 to 69 years, respectively. Ultrafast computed tomography is an excellent tool for detecting and quantifying coronary artery calcium.

Adult↗
PubMed1988

The effects of morbid obesity and the Garren-Edwards gastric bubble on solid phase gastric emptying.

Rapid solid phase gastric emptying (SPGE) resulting in decreased satiety is postulated to be a contributing factor to obesity. Twenty-six morbidly obese patients with a weight range of 189-523 lb were entered into the Garren-Edwards gastric bubble program. SPGE studies were performed pre-bubble implantation and repeated within 2 wk after bubble implant. There was no significant difference between study patients pre-bubble insertion emptying time and the normal population curve. Emptying time was found to be significantly increased, post-bubble implant, compared with pre-bubble implant over five time periods of testing. The Garren-Edwards gastric bubble has been used as a method for inducing early satiety for the morbidly obese patient. It has been postulated that delay of SPGE would be associated with satiety. Our patients experienced satiety despite their more rapid SPGE. Thus, the satiety which was experienced by our subjects was not on the basis of delayed SPGE, as previously thought.

Adolescent↗
PubMed1982

Quantitation of left ventricular regurgitant fraction by first pass radionuclide angiocardiography.

A new technique for quantitating left ventricular regurgitant fraction from first pass radionuclide angiocardiographic studies is described. The technique involves measurement of the total number of counts ejected from the right and left ventricles (CR and CL, respectively). In the absence of any valve insufficiency and equal counting efficiency from each ventricle, CR/CL = 1. In the presence of mitral or aortic insufficiency, or both, the regurgitant fraction can be calculated as (CL -- CR)/CL, if no right ventricular regurgitation is present. In this report the theoretical derivation of the method and practical aspects of measuring CL and CR are presented. The technique was tried in a small group of 5 normal volunteers, 7 patients studied with cardiac catheterization without regurgitation and 22 patients with mitral or aortic insufficiency, or both. Excellent correlation was found with cardiac catheterization data in the latter group (r = 0.86, n = 22). This method appears to be a simple and accurate technique for measuring left ventricular regurgitant fraction due to mitral or aortic valve disease, or both.

Adult↗
PubMed1981

The role of biliary scintigraphy and ultrasonography in the diagnosis of cholecystitis.

The scintigraphic and sonographic findings in 70 patients with pathologically confirmed gallbladder disease are described. Fifty-two patients were found to have had acute cholecystitis. All 52 patients (100%) had non-visualized of the gallbladder on scintigraphy. Of these patients, 71% had abnormal ultrasound examinations and 29% had normal ultrasound examination. Eighteen patients were proven to have chronic cholecystitis. All 18 (100%) had an abnormal ultrasound examination. Four patients (22%) had non-visualization of the gallbladder on scintigraphy producing a false-positive incidence of approximately 6% for acute cholecystitis. The predictive value of scintigraphy in the patient with suspected acute cholecystitis was 94%. A combination of ultrasound and scintigraphy yielded a sensitivity of 100% in the detection of gallbladder disease in the 70 patients.

Cholecystitis↗
PubMed1980

Ultrasound of the whole breast utilizing a dedicated automated breast scanner.

Innovations in design of a dedicated breast scanner resulted in automation of the scanning process, the production of high resolution images of the whole breast and an efficient mode of image review. The results of clinical evaluation of the prototype of this breast scanner investigating normal breasts as well as benign and malignant breast lesions are presented.

Adenocarcinoma, Scirrhous↗
PubMed1979

Evaluation of segmental left ventricular wall motion by equilibrium gated radionuclide ventriculography.

The ability of equilibrium gated radionuclide ventriculography to detect segmental left ventricular (LV) wall motion abnormalities was determined in 26 patients undergoing cardiac catheterization. Multiple gated studies obtained in 30 degrees right anterior oblique and 45 degrees left anterior oblique projections, played back in a movie format, were compared to the corresponding LV ventriculograms. The LV wall in the two projections was divided into eight segments. Each segment was graded as normal, hypokinetic, akinetic, dyskinetic, or indeterminate. Thirteen percent of the segments in the gated images were indeterminate; 24 out of 27 of these were proximal or distal inferior wall segments. There was exact agreement in 86% of the remaining segments. The sensitivity of the radionuclide technique for detecting normal versus any abnormal wall motion was 71%, with a specificity of 99%. Equilibrium gated ventriculography is an excellent noninvasive technique for evaluating segmental LV wall motion. It is least reliable in assessing the proximal inferior wall and interventricular septum.

Adult↗