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J Tieman

Publications and source records attributed to J Tieman.

83 records · Page 5Linked to original sources
PubMed1997

Semi-automated extraction of brain contours from MRI.

We compared brain volumes computed by trained operators using the BRAIN-MAP algorithm, which automatically extracts the contours of the brain from gradient-echo magnetic resonance images. The images of 19 subjects randomly selected from a group of normals and a group of patients with dementia were included. BRAIN-MAP found brain perimeters that were on the average ca. 3% tighter than those obtained by two experienced operators. Between-operator and within-operator reproducibility of the analyses were also estimated and found to be (-0.13 +/- 0.51)% and (-0.63 +/- 0.08)%, respectively. Replicate volume measurement by the computer alone provided a reproducibility of (0.44 +/- 0.46)%.

Adult↗
PubMed1994

Comparison of the precision of two standardized co-ordinate systems for the quantitation of brain anatomy: preliminary results.

We assessed reproducible definition of two standardized co-ordinate systems for intersubject analysis of brain images. The baselines in the two co-ordinate systems were a modification of the canthomeatal (mCM) line and the anterior-posterior commissural (AC-PC) line. Axial spin-echo MR images of four subjects at 1.5T were used. Operator error was computed from the replicate analyses of two operators. The mCM line was determined by the lens of the eye and the internal auditory canal, and the AC-PC line was determined by the intersection of AC and PC with the interhemispheric fissure. Reproducibility of the mCM markers (SD = 0.59 mm) did not differ significantly from that of the AC-PC line (SD = 0.68 mm). The measurement error of the angle of the baseline (delta alpha), however, was more than 7 times as large for the AC-PC line as for the mCM line. An additional error affecting the rostrocaudal rotation of the co-ordinate systems, attributable to the distance between the anatomic markers, was 2.1 and 3.6 degrees (3 mm and 5 mm slice thickness) for the mCM co-ordinate system and 8.2 and 11.0 degrees (3 mm and 5 mm slice thickness) for the AC-PC system. The AC-PC line based co-ordinate system is therefore, less reproducible than the mCM line based system. This could be improved if a combination of axial and sagittal images were used for the definition of the AC-PC line.

Brain↗
PubMed1993

Temporal lobe regions on magnetic resonance imaging identify patients with early Alzheimer's disease.

OBJECTIVE: The goal of the study was to examine the volume of selected brain regions in a group of mildly impaired patients with Alzheimer's disease (AD). Five regions were selected for analysis, all of which have been reported to show substantial change in the majority of patients with AD at some time in the course of disease. DESIGN: Case-control study with the experimenter "blinded." SETTING: Hospital-based magnetic resonance imaging center. PARTICIPANTS: Fifteen subjects, eight patients with the diagnosis of probable dementia of the Alzheimer type made in concordance with National Institute of Neurological and Communicative Diseases and Stroke/Alzheimer's Disease and Related Disorders Association criteria and seven age-matched healthy control subjects. RESULTS: Three of the volumetric measures were significantly different between patients with AD and controls: the hippocampus, the temporal horn of the lateral ventricles, and the temporal lobe. Two of the measures did not significantly differentiate patients with AD and controls: the amygdala and the basal forebrain. A discriminant function analysis demonstrated that a linear combination of the volumes of the hippocampus and the temporal horn of the lateral ventricles differentiated 100% of the patients and controls from one another. CONCLUSIONS: The results suggest that the hippocampus and the temporal horn of the lateral ventricles may be useful as antemortem markers of AD in mildly impaired patients.

Aged↗
PubMed1992

Comparative analysis of computed tomographic and magnetic resonance imaging scans in Alzheimer patients and controls.

Ten patients with Alzheimer's disease underwent computed tomography and magnetic resonance imaging at the same point in time. The mean Mini-Mental State examination score of the patients was 23, indicating that they were mildly impaired. Ten age-equivalent controls also obtained computed tomographic and magnetic resonance imaging scans. A semiautomated computer program analyzed nine comparable regions of interest on each set of scans. When regions of interest from both types of scans were combined in the same discriminant function analysis, the first two variables selected were from the magnetic resonance imaging data set, and they significantly differentiated 95% of the patients and controls.

Aged↗
PubMed1991

Application of automated MRI volumetric measurement techniques to the ventricular system in schizophrenics and normal controls.

As an initial approach to computer-automated segmentation of cerebral spinal fluid (CSF) vs. brain parenchyma in MR scans, and the transformation of these data sets into volumetric information and 3D display, we examined the ventricular system in a sample of ten chronic schizophrenics with primarily positive symptoms and 12 normal subjects. While no significant differences were noted between groups on volumetric measures of ventricular brain ratio or lateral ventricle size, normals showed a pattern of left greater than right lateral ventricular volume asymmetry not present in the schizophrenics. Within the schizophrenic group, departure from the normal left greater than right pattern was highly correlated with thought disorder.

Adult↗
PubMedDate not supplied

Rapid three-dimensional surface reconstruction of magnetic resonance images of large arteries and veins: a preliminary evaluation of clinical utility.

We have implemented a computerized system for relatively rapid (< 1 h) three-dimensional (3D) surface rendering of flow-sensitive (gradient refocused) magnetic resonance images. The method has been applied in 8 patients with six different clinical problems and was found to enhance understanding of normal and abnormal aortic, caval, and portosystemic venous anatomy. 3D images are useful for communicating complex anatomic information and may help with difficult diagnoses. Advantages and limitations of the present system are discussed.

Aortic Dissection↗