Biomedical subjects

T J Doyle

Publications and source records attributed to T J Doyle.

39 records · Page 3Linked to original sources

PubMedDate not supplied

Short TE hydrogen-1 spectroscopic MR imaging of normal human brain: reproducibility studies.

Studies have been performed to evaluate the reproducibility of longitudinal acquisitions with short TE spectroscopic magnetic resonance (MR) imaging of human brain. In healthy volunteers, the ratios of N-acetyl-aspartate (NAA) and choline (Cho) with respect to total creatine (Cr) (creatine and phosphocreatine) have been examined in terms of voxel-to-voxel, acquisition-to-acquisition, and subject-to-subject variation. Overall coefficients of variation for NAA/Cr ratios and Cho/Cr ratios were 18% and 16%, respectively. The interacquisition variation was not statistically significant (P = .05) for either ratio. In terms of F ratios, the dominant source of variation in the NAA/Cr ratio was intersubject variability, whereas for the Cho/Cr ratio the dominant source of variation was intervoxel variability. Consequences of spectroscopic processing with spatial apodization and postacquisition water suppression and resolution enhancement were also examined. Such reproducibility studies are crucial if longitudinal spectroscopic evaluations are to be performed in a clinical setting to follow the natural course of disease states or the effects of therapy.

Adult↗

PubMedDate not supplied

Accuracy and reproducibility in volumetric analysis of multiple sclerosis lesions.

The accuracy and reproducibility of dual-contrast segmentation based on nonparametric feature map analysis have been investigated in a multicomponent gelatin phantom. The root mean square errors in volume ranged from 0.02 cm3 for small volumes to 3.8 cm3 for larger volumes, with a mean error of 0.97 cm3. Average inter- and intraobserver coefficients of variation were found to be < 7% for all compartments. To evaluate the reproducibility of segmentation of clinical image data, volumes of total brain, CSF, and multiple sclerosis (MS) lesions were obtained from five image sets of MS patients. Inter- and intraobserver coefficients of variations were computed for the patient data and were found to be < 5% for brain, 17% for CSF, and 20% for MS lesions. Such variations were found to be reduced by appropriate preprocessing of the images.

Adult↗

PubMedDate not supplied

Using remotely sensed data to identify areas at risk for hantavirus pulmonary syndrome.

The 1993 U.S. hantavirus pulmonary syndrome (HPS) outbreak was attributed to environmental conditions and increased rodent populations caused by unusual weather in 1991- 92. In a case-control study to test this hypothesis, we estimated precipitation at 28 HPS and 170 control sites during the springs of 1992 and 1993 and compared it with precipitation during the previous 6 years by using rainfall patterns at 196 weather stations. We also used elevation data and Landsat Thematic Mapper satellite imagery collected the year before the outbreak to estimate HPS risk by logistic regression analysis. Rainfall at case sites was not higher during 1992-93 than in previous years. However, elevation, as well as satellite data, showed association between environmental conditions and HPS risk the following year. Repeated analysis using satellite imagery from 1995 showed substantial decrease in medium- to high-risk areas. Only one case of HPS was identified in 1996.

Animals↗