T1-weighted Volumetric Magnetic Resonance Imaging Research Articles

Increased sensitivity to pathological brain changes using co-registration of magnetic resonance imaging scans

To compare automatic software-based co-registration of serial magnetic resonance imaging (MRI) scans with conventional visual comparison, by expert neuroradiologists. Sixty-four patients who were referred to our epilepsy MRI unit for cerebral imaging were identified as having potentially, non-, or slow-growing lesions or cerebral atrophy and followed with sequential scans over a period of up to 8 years, resulting in a total of 92 pairs of scans. Scans were categorized as showing either lesions or atrophy. Each pair of scans was reviewed twice for the presence of change, with and without co-registration, performed using automated software. Co-registration and visual reporting without co-registration were discordant in the lesions group in nine out of 69 datasets (13%), and in 16 out of 23 pairs of scans in the atrophy group (69%). The most common cause of discordance was visual reporting not detecting changes apparent by co-registration. In three cases, changes detected visually were not detected following co-registration. In the group of patients studied, co-registration was more sensitive for detecting changes than visual comparison, particularly with respect to atrophic changes of the brain. With the increasing availability of sophisticated independent consoles attached to MRI scanners that may be used for image co-registration, we propose that serial T1-weighted volumetric MRI brain co-registration should be considered for integration into routine clinical practice to assess patients with suspected progressive disease.

Visual Assessment of Atrophy on Magnetic Resonance Imaging in the Diagnosis of Pathologically Confirmed Young-Onset Dementias

To investigate the diagnostic accuracy of visual inspection of magnetic resonance imaging (MRI) in a range of pathologically confirmed diseases causing young-onset dementia and to assess the sensitivity and specificity of atrophy patterns for Alzheimer disease (AD) and frontotemporal lobar degeneration (FTLD). Sixty-two patients with pathologically confirmed diseases that may present as young-onset dementia were selected from a biopsy and postmortem series. The first diagnostic T1-weighted volumetric MRI was obtained for each patient, together with images from 22 healthy control subjects. All MRIs were assessed for regional atrophy independently by 3 neuroradiologists, blinded to all clinical details except age. Observers were also asked to use their clinical judgment to form a diagnosis. Eighty-seven percent of dementia cases were distinguished from controls after visual inspection of MRI, and a correct pathologically confirmed diagnosis was given in 58% of cases. Hippocampal atrophy was noted in 92% of AD cases but was commonly seen in other dementias and controls. A bilateral symmetrical pattern of hippocampal atrophy discriminated AD from FTLD with 47% specificity, while posterior greater than anterior gradient of atrophy was 92% specific for AD. Atrophy of the anterior, inferior, and lateral temporal lobes was suggestive of FTLD pathology (> or =90% sensitivity), while anterior greater than posterior gradient of atrophy and hemispheric asymmetry of atrophy were each at least 85% specific for FTLD. Despite variation and overlap of atrophy patterns, visual inspection of regional atrophy on MRI may aid in discriminating AD and FTLD.

Effect of Leptin Replacement on Brain Structure in Genetically Leptin-Deficient Adults

The hormone leptin profoundly affects body weight and metabolism. Three human adults (two women, 35 and 40 yr old; one man, age 27) have been identified with a recessive mutation in the ob gene, which is homologous to the mutation in ob/ob mice, and produces leptin deficiency and morbid obesity. Because leptin replacement increases brain weight and changes brain protein and DNA content in ob/ob mice, we hypothesized that analogous treatment of leptin-deficient humans would alter brain tissue composition. Volumetric T1-weighted magnetic resonance images of the brain were acquired before and at 6 and 18 months after initiation of replacement therapy (daily sc injections of recombinant methionyl human leptin), which produced dramatic loss in body weight. We used voxel-based morphometry to test for increased gray matter tissue concentration after initiation of leptin replacement and detected increases at 6 months in the anterior cingulate gyrus, the inferior parietal lobule, and the cerebellum. These increases were maintained for over 18 months, with identical stereotaxic coordinates of the maxima for the effects. Our findings suggest that leptin can have sustained effects on tissue composition in the human brain and broaden the potential spectrum of leptin's influence beyond feeding behavior and endocrine function.

Statistical analyses of structural magnetic resonance imaging of the head of the caudate nucleus in Colombian children with attention-deficit hyperactivity disorder.

Magnetic resonance imaging (MRI) studies of the caudate nucleus have reported reversal asymmetry and alterations of its size, suggesting a striate cortical disorder related to attention-deficit hyperactivity disorder (ADHD). The objective was to evaluate whether alterations of the asymmetry and size of the caudate nucleus head exist in a sample of well-controlled 7- to 11-year-old Colombian children, with different types of ADHD. Two groups of cases-ADHD of the combined type and ADHD of the inattentive type-and one control group, were selected. Multiple methods for assessing ADHD (rating scales, psychologic.interview, neurologic history and examination, and neuropsychologic evaluation) were used to confirm the diagnoses. Participants with a history of language disorder, learning disabilities, depression, and other major neurologic and psychiatric conditions were excluded. Finally all groups had 15 children, matched by sex (7 male, 8 female), age, socioeconomic status, and grade. Height, weight, head circumference, and encephalic index were statistically controlled. Three T1-weighted volumetric (three-dimensional) MRI slides of the caudate nucleus head were obtained with a 1.5-Tesla Gyroscan apparatus. The control group had a significantly higher Wechsler Full-Scale IQ than the groups with ADHD of the combined type and ADHD of the inattentive type (P < .001). Volumes from the left caudate nucleus head were significantly larger than volumes from the right in all groups (P < .001). There were no group differences when volumes were compared between groups. All of the groups had left caudate nucleus head volumes significantly higher than right, although there were no between-group differences. The results in relation to previous studies are discussed.

Superior temporal gyral volumes and laterality correlates of auditory hallucinations in schizophrenia

Background: Previous studies have reported significant correlations, indicating an emerging relationship, between severity of auditory hallucinations and reduced size of temporal lobe cortical regions implicated in language processing. The present study used high-resolution magnetic resonance imaging (MRI) scanning, along with assessment of functional lateralization via a dichotic listening task (DLT), to extend these findings. Methods: Thirty patients with schizophrenia and a history of auditory hallucinations participated in the study. All were completely right-handed. Eleven subjects were currently hallucinating at the time of the study. Volumetric T1-weighted MRI scans were obtained and regions of interest were manually traced using the BRAINS package (Andreasen et al 1993). Whole brain, bilateral temporal lobe, and anterior superior temporal gyrus volumes were calculated. Subjects completed a binaural consonant–vowel DLT. Results: Increased severity of hallucinatory experience was significantly associated with smaller left anterior superior temporal gyrus volumes. Current hallucinators demonstrated a reduction in right ear advantage on the DLT. Conclusions: The results suggest that auditory hallucinations are subserved by a trait-like dysfunction in language-related neural networks, of which the superior temporal cortex forms one component. The findings are also consistent with theories proposing abnormal lateralization in the etiology of auditory hallucinations.

Gyri of the human neocortex: an MRI-based analysis of volume and variance.

This magnetic resonance imaging (MRI)-based morphometric analysis of cortical topography in the human brain is based upon the segmentation and parcellation of volumetric T1-weighted MRI data for a set of 20 young adult brains including 10 males and 10 females. For the most part, each parcellation unit (PU) of the neocortex corresponds to a single or a portion of a single gyrus. The volumes of each PU were computed for each brain. Subsets of PUs were also grouped so as to represent the neocortex for the frontal, temporal, parietal and occipital lobes. The coefficient of variation of the mean volume of total neocortex and that of the neocortex assigned to individual lobes cluster around 10%, whereas that of neocortex assigned to the individual gyri (PU) is more than twice that value. Approximately 80% of the total variance in gyral volume arises from determinants interactive for individual and specific gyri, while only approximately 10% of the total variance appears to be a reflection of uniform scaling to total neocortical volume. Sexual dimorphism contributes a pervasive though relatively small component of this variance. These results have implications for the study of structure-function correlation, and the proper statistical methods of handling volumetric data in morphometric studies. In addition, the nature of the covariance structure of the data will lead to future hypotheses regarding the relationships between the various potential genetic and epigenetic gyral influencing factors.

Superior temporal gyral volumes and laterality correlates of auditory hallucinations in schizophrenia

Abstract Background: Previous studies have reported significant correlations, indicating an emerging relationship, between severity of auditory hallucinations and reduced size of temporal lobe cortical regions implicated in language processing. The present study used high-resolution magnetic resonance imaging (MRI) scanning, along with assessment of functional lateralization via a dichotic listening task (DLT), to extend these findings. Methods: Thirty patients with schizophrenia and a history of auditory hallucinations participated in the study. All were completely right-handed. Eleven subjects were currently hallucinating at the time of the study. Volumetric T1-weighted MRI scans were obtained and regions of interest were manually traced using the BRAINS package (Andreasen et al 1993) . Whole brain, bilateral temporal lobe, and anterior superior temporal gyrus volumes were calculated. Subjects completed a binaural consonant–vowel DLT. Results: Increased severity of hallucinatory experience was significantly associated with smaller left anterior superior temporal gyrus volumes. Current hallucinators demonstrated a reduction in right ear advantage on the DLT. Conclusions: The results suggest that auditory hallucinations are subserved by a trait-like dysfunction in language-related neural networks, of which the superior temporal cortex forms one component. The findings are also consistent with theories proposing abnormal lateralization in the etiology of auditory hallucinations.