Biomedical subjects

R M Fleming

Publications and source records attributed to R M Fleming.

39 records · Page 3Linked to original sources

PubMedDate not supplied

A high-throughput search for electronic materials-thin-film dielectrics.

Parallel synthesis together with high-throughput screening was used to identify candidate materials for integrated circuit applications that demand a superior high permittivity dielectric thin film. Specifically, we developed a "continuous-composition spread" (CCS) technique to synthesize much of a pseudoternary oxide system in a single deposition and used this in conjunction with a high-throughput measurement protocol, thereby allowing each chemical system to be deposited and evaluated in about 24 h. This approach led to the identification of compositions in the Zr-Sn-Ti-O system with promising properties. The same technique was used to determine the optimum compositions as a function of processing parameters. Films with the composition Zr(.2)Sn(.2)Ti(.6)O(2) were then prepared using a conventional synthetic technique (on-axis sputtering) and were verified to have excellent properties. Thus, the CCS technique has demonstrated utility in rapidly identifying and developing a useful new material.

Combinatorial Chemistry Techniques↗

PubMedDate not supplied

Using quantitative coronary arteriography to redefine SPECT sensitivity and specificity.

Previous studies looking at the sensitivity, specificity, and predictive accuracy of single photon emission computed tomography (SPECT) have been based upon the results obtained by visual interpretation of coronary arteriograms. Since the results of visual and quantitative determination of percent diameter stenosis have been shown to be statistically different, the results obtained from SPECT imaging when compared to quantitative methods for assessing coronary artery disease would be expected to provide a more correct assessment of sensitivity, specificity, and predictive accuracy. To determine the "true" sensitivity, specificity, and predictive accuracy of SPECT in diagnosing coronary artery disease, this study compared the results obtained in 44 SPECT images (20 thallium and 24 teboroxime) with the results obtained when quantitative coronary arteriography was used to analyze the coronary arteriograms. These 44 cases were then compared against 8 different definitions of significant coronary artery disease, varying from 30 to 80%, to yield 352 comparisons. The maximum specificity and predictive accuracy was found when 45% diameter stenosis was used to define the presence or absence of significant disease. At 45% diameter stenosis, SPECT imaging demonstrated an 86% sensitivity, 78% specificity, and 94% predictive accuracy with only 6% false positives. In 100% of the cases where 45% diameter stenosis was used to define the presence of disease and exercise failed to demonstrate ST segment changes or angina, when SPECT imaging demonstrated a perfusion defect(s), quantitative coronary arteriography agreed with SPECT imaging results.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMedDate not supplied

Detecting coronary artery disease using SPECT imaging: a comparison of thallium-201 and teboroxime.

Thirty subjects underwent single photon emission computed tomography (SPECT) imaging with technetium-99m teboroxime (TEBO). Of these, 26 underwent thallium SPECT imaging and 25 underwent quantitative coronary arteriography (QCA). Twenty-one of the subjects underwent all three studies. SPECT images were reviewed by two independent observers blinded to the clinical data. Stenoses were considered significant if there was a greater than or equal to 50% diameter narrowing as defined by QCA analysis of the coronary arteriograms. The overall sensitivity and specificity was 78% and 78%, respectively, for thallium-201. The overall sensitivity and specificity for teboroxime was 72% and 80%, respectively. The results obtained for these two tracers were not statistically different. Some of the false-positive results obtained from teboroxime imaging appear to have been due to the 10-min acquisition protocol and can be reduced with the use of new software programs using a continuous 3-min acquisition and dipyridamole. Teboroxime's rapid biologic half-life allows completion of SPECT imaging within 60-90 min, compared with the minimum of 4 h required for thallium SPECT imaging.

Coronary Angiography↗