Biomedical subjects

W G Staal

Publications and source records attributed to W G Staal.

6 recordsLinked to original sources

PubMed2001

Automated separation of gray and white matter from MR images of the human brain.

A simple automatic procedure for segmentation of gray and white matter in high resolution 1.5T T1-weighted MR human brain images was developed and validated. The algorithm is based on histogram shape analysis of MR images that were corrected for scanner nonuniformity. Calibration and validation was done on a set of 80 MR images of human brains. The automatic method's values for the gray and white matter volumes were compared with the values from thresholds set twice by the best three of six raters. The automatic procedure was shown to perform as good as the best rater, where the average result of the best three raters was taken as reference. The method was also compared with two other histogram-based threshold methods, which yielded comparable results. The conclusion of the study thus is that automated threshold based methods can separate gray and white matter from MR brain images as reliably as human raters using a thresholding procedure.

Adult↗

PubMed2001

Structural brain abnormalities in chronic schizophrenia at the extremes of the outcome spectrum.

OBJECTIVE: This study investigated the relationship between outcome and structural brain abnormalities in schizophrenia. METHOD: Intracranial volume and volumes of the cerebrum, gray and white matter, lateral and third ventricles, frontal lobes, thalamus, and cerebellum were measured in 20 patients with a poor outcome, 25 with a favorable outcome, and 23 healthy comparison subjects with magnetic resonance imaging. RESULTS: Thalamic volume was significantly smaller both in poor-outcome patients and good-outcome patients. In contrast, only poor-outcome patients displayed significantly smaller cerebral gray matter, particularly prefrontal, and enlargement of the lateral and third ventricles. No significant differences were found for intracranial, cerebellar, or cortical CSF volumes. CONCLUSIONS: Smaller thalamic volumes in schizophrenia may reflect a greater susceptibility for the disorder and seem unrelated to outcome. In contrast, gray matter volume loss of the cerebrum, particularly in the frontal lobes, and lateral and third ventricular enlargement appear related to outcome in schizophrenia.

Age of Onset↗

PubMed2000

Neuropsychological dysfunctions in siblings discordant for schizophrenia.

Although cognitive impairments are well recognized in patients with schizophrenia, it is unclear which impairments are due to a genetic predisposition and which are caused by secondary disease effects or phenotype. The aim of this study is to investigate the possible relationship between genetic vulnerability to schizophrenia and cognitive functioning. Three groups of subjects were compared: 14 patients with schizophrenia, 15 healthy siblings and 32 healthy control subjects. All subjects were tested neuropsychologically. The raw test data were rescaled to standard equivalents (z-scores). Subjects' z scores on tests assessing the same cognitive domain were clustered and analyzed. Differences in cognitive functioning were found in the domains of abstraction, attention, executive functioning, spatial memory, and sensory-motor functioning. The schizophrenic probands were impaired on all these five domains whereas the healthy probands showed impairments on executive functioning and partially on sensory-motor functioning. Furthermore, for spatial memory the significant finding could mainly be attributed to impaired functioning in the patients, but not healthy siblings or control subjects, whereas for executive functioning patients and healthy siblings seemed equally impaired as compared to control subjects. The planning time of the Tower of London (TOL) and the initiation time of the Motor Planning Task (MPT) were used for measures of executive functioning, while the 'time to move of the Motor Planning Task' was used as measures of sensory motor functioning. These results suggest that the cognitive abnormalities in schizophrenia that may be related to genotype are represented in the domain of executive functioning and to some extent in the domain of sensory-motor functioning.

Adult↗

PubMed2000

Structural brain abnormalities in patients with schizophrenia and their healthy siblings.

OBJECTIVE: The authors sought to investigate the contribution of genotype on structural brain abnormalities in schizophrenia. METHOD: Intracranial volumes and volumes of the cerebrum, white and gray matter, lateral and third ventricles, frontal lobes, caudate nucleus, amygdala, hippocampus, parahippocampal gyrus, and the cerebellum were measured in 32 same-sex siblings discordant for schizophrenia and 32 matched comparison subjects by means of magnetic resonance imaging. RESULTS: Third ventricle volumes did not differ between the schizophrenic patients and their healthy siblings. However, both had higher third ventricle volumes than did the comparison subjects. The schizophrenic patients had lower cerebrum volumes than did the comparison subjects, whereas the cerebrum volume of the healthy siblings did not significantly differ from the patients or comparison subjects. Additionally, patients with schizophrenia displayed a volume reduction of the frontal lobe gray matter and a volume increase of the caudate nuclei and lateral ventricles compared to both their healthy siblings and comparison subjects. Intracranial volume, CSF volume, or volumes of the cerebellum, amygdala, hippocampus, or the parahippocampal gyrus did not significantly differ among the patients, siblings, and comparison subjects. CONCLUSIONS: Healthy siblings share third ventricle enlargement with their affected relatives and may partially display a reduction in cerebral volume. These findings suggest that third ventricular enlargement, and to some extent cerebral volume decrease, may be related to genetic defects that produce a susceptibility to schizophrenia.

Adult↗

PubMed1999

Outcome of schizophrenia in relation to brain abnormalities.

This article reviews the 21 studies that investigated possible relationships between structural brain abnormalities and outcome in schizophrenia. Fifteen studies used computer tomography to visualize brain morphology. In these studies, images were obtained of the ventricles but not of specific brain regions. The remaining six studies used magnetic resonance imaging, examining possible relationships between outcome, ventricular size, and specific brain regions. One out of two studies found relationships between brain structure and outcome. The data suggest that the extent of ventricular enlargement in patients with schizophrenia may be related to outcome. No clear relationship between outcome and changes in specific brain regions was found. Apart from considerations about the methodology of measuring different brain regions, the procedure used to measure outcome is important. Outcome, as it is assessed at various points during the course of illness, may be variable and seems to fluctuate during the first 10 to 15 years of disease. Significantly, to date no studies relating outcome to brain structure have used patient samples with a duration of illness longer than 15 years.

Adult↗

PubMed1998

Partial volume decrease of the thalamus in relatives of patients with schizophrenia.

OBJECTIVE: The authors' goal was to compare the thalamic, total brain, and intracranial volumes of patients with schizophrenia, their healthy siblings, and normal comparison subjects. METHOD: Magnetic resonance imaging (MRI) brain scans were obtained for 32 same-sex siblings who were discordant for schizophrenia and 32 matched normal comparison subjects. RESULTS: Mean total thalamic volume, corrected for total brain volume, was significantly different among affected siblings, unaffected siblings, and comparison subjects. Thalamic volume was smallest in the patients; thalamic volume in their siblings was smaller than that of comparison subjects but larger than that of the patients with schizophrenia. CONCLUSIONS: These results suggest that healthy siblings of patients with schizophrenia partially share the thalamic abnormalities of their affected relatives.

Brain↗