Magnetic-resonance morphometry: Image-analysis methodology development for affective disorder

Morphologic, distributional, volumetric, and intensity characterization of periventricular hyperintensities

BACKGROUND AND PURPOSE

White matter hyperintensities are characteristic of old age and identifiable on FLAIR and T2-weighted MR imaging. They are typically separated into periventricular or deep categories. It is unclear whether the innermost segment of periventricular white matter hyperintensities is truly abnormal or is imaging artifacts.

MATERIALS AND METHODS

We used FLAIR MR imaging from 665 community-dwelling subjects 72-73 years of age without dementia. Periventricular white matter hyperintensities were visually allocated into 4 categories: 1) thin white line; 2) thick rim; 3) penetrating toward or confluent with deep white matter hyperintensities; and 4) diffuse ill-defined, labeled as "subtle extended periventricular white matter hyperintensities." We measured the maximum intensity and width of the periventricular white matter hyperintensities, mapped all white matter hyperintensities in 3D, and investigated associations between each category and hypertension, stroke, diabetes, hypercholesterolemia, cardiovascular disease, and total white matter hyperintensity volume.

RESULTS

The intensity patterns and morphologic features were different for each periventricular white matter hyperintensity category. Both the widths (r = 0.61, P < .001) and intensities (r = 0.51, P < .001) correlated with total white matter hyperintensity volume and with each other (r = 0.55, P < .001) for all categories with the exception of subtle extended periventricular white matter hyperintensities, largely characterized by evidence of erratic, ill-defined, and fragmented pale white matter hyperintensities (width: r = 0.02, P = .11; intensity: r = 0.02, P = .84). The prevalence of hypertension, hypercholesterolemia, and neuroradiologic evidence of stroke increased from periventricular white matter hyperintensity categories 1 to 3. The mean periventricular white matter hyperintensity width was significantly larger in subjects with hypertension (mean difference = 0.5 mm, P = .029) or evidence of stroke (mean difference = 1 mm, P < .001). 3D mapping revealed that periventricular white matter hyperintensities were discontinuous with deep white matter hyperintensities in all categories, except only in particular regions in brains with category 3.

CONCLUSIONS

Periventricular white matter hyperintensity intensity levels, distribution, and association with risk factors and disease suggest that in old age, these are true tissue abnormalities and therefore should not be dismissed as artifacts. Dichotomizing periventricular and deep white matter hyperintensities by continuity from the ventricle edge toward the deep white matter is possible.

Hyperintense MRI lesions in bipolar disorder: A meta-analysis and review

BACKGROUND

Cortical and subcortical hyperintensities in magnetic resonance imaging (MRI) scans are thought to represent areas of ischemic damage to brain tissue. Researchers have focused on the possible role these lesions may have in psychiatric disorders, including bipolar disorder. In 1997, the proposed 'vascular mania' diagnosis suggested utilizing not only the presence of strokes, but also confluent hyperintensities in its diagnostic criteria. This study was conducted to use meta-analytic techniques to investigate the association of hyperintensities and bipolar illness and to evaluate the current state of the literature.

METHODS

Using the PubMed and MEDLINE databases, we conducted a systematic literature search of studies investigating hyperintensities in subjects with bipolar disorder and controls or other psychiatric illnesses. We identified 44 publications from which 35 studies were included for review and 27 were selected for meta-analysis. Summary statistics of the prevalence were estimated through odds-ratios and confidence interval. Heterogeneity of the results across studies was tested using Q-statistics.

RESULTS

Meta-analysis identified an odds ratio of 2.5 (95% CI 1.9, 3.3) for hyperintensities in bipolar subjects compared to controls; however, there was significant heterogeneity among the studies (Q-statistics = 32; p = 0.04). This finding was most prominent for adolescents and children where the odds ratio was 5.7 (95% CI 2.3, 13.7). Deep white matter hyperintensities (odd ratio 3.2; 95% CI 2.2, 4.5) and subcortical grey matter hyperintensities (odds ratio 2.7; 95% CI 1.3, 2.9) were more strongly associated with bipolar subjects. There were no differences between bipolar subjects and controls for perivascular hyperintensities (odds ratio 1.3; 95% CI 0.8, 1.9). Though hyperintensities were numerically greater in bipolar subjects, meta-analysis did not demonstrate any significant differences between bipolar subjects and unipolar depression subjects (OR 1.6; 95% CI 0.9, 2.7) nor subjects with schizophrenia (OR 1.5; 95% CI 0.9, 2.7).

CONCLUSIONS

This meta-analysis continues to support the association of bipolar disorder and hyperintensities, especially in the deep white matter and subcortical grey matter. It also highlights the increased incidence in children and adolescence with bipolar disorder. However, hyperintensities are not specific to bipolar disorder, but appear at similar rates in unipolar depression and schizophrenia. Thus, the role of hyperintensities in the pathogenesis, pathophysiology, and treatment of bipolar disorder remains unclear. Further studies are required that are large enough to decrease the heterogeneity of the samples and MRI techniques, assess size and location of hyperintensities, and the impact on treatment response. Coordination with newer imaging techniques, such as diffusion tensor imaging (DTI) may be especially helpful in understanding the pathology of these lesions.

Frontal signal hyperintensities in mania in old age

OBJECTIVE

Signal hyperintensities (SH) on magnetic resonance (MR) imaging have been associated with increased age and with mood disorders. Frontal and subcortical neuropathology has been implicated in the pathophysiology of mania and bipolar disorders. The authors assessed frontal and subcortical SH in elderly bipolar manic patients and the comparison group, and hypothesized that SH scores would be greater in the patient group.

METHOD

MR imaging was performed in patients aged > or = 60 years with bipolar disorder, mania, and in a same-aged community comparison group. SH were rated blindly using the Boyko system. Frontal deep white matter and basal ganglia SH were assessed in the left and right hemispheres.

RESULTS

SH scores were significantly greater in patients (N = 40) than the comparison group (N = 15) in frontal deep white matter (left: p = 0.003; right: p = 0.023) based on Mann-Whitney two-sample exact tests. The SH scores in the subcortical gray regions overlapped in these groups. In patients, higher right frontal SH scores were associated with later age at onset of mania.

CONCLUSIONS

Frontal deep white matter SH may be increased in elders with bipolar disorder. Further study of the relationship of SH to age at onset in elders is warranted.

Hypofrontality and microvascular dysregulation in remitted late-onset depression assessed by functional near-infrared spectroscopy

Accumulated evidence suggests the involvement of vascular factors in late-onset depression. Late-onset depression has characteristics of poor outcome, cognitive decline, and high prevalence rather than early-onset depression. The aim of the present study was to determine whether or not the functional hypofrontality--that is, hypoperfusion and hypometabolism in the frontal lobes-seen in late-onset depression is a trait-dependent abnormality of microvascular regulation. This study was conducted on 10 patients with remitted late-onset major depressive disorder (MDD) and 10 healthy volunteers matched for vascular factors and subcortical, or white matter, hyperintensities (WMH). Using near-infrared spectroscopy combined with magnetic resonance imaging, we investigated the microvascular reactivity in the prefrontal cortex during a cognitive task and during carbon dioxide (CO(2)) inhalation. Activation of the prefrontal cortex during the cognitive task was significantly less in patients as compared with controls, although task performance was not significantly different between the two groups. In the patients, a tendency of negative correlation between the reduced prefrontal activation during a cognitive task and the severity of hyperintensity in periventricular region was observed. Vasomotor reactivity to CO(2) inhalation was significantly lower in the patients than in the controls. Although there was no significant association between the activation during the cognitive and that during the CO(2) inhalation task, the present results suggest that prefrontal microvascular dysregulation as shown by NIRS is involved in the pathophysiological basis of functional hypofrontality in late-onset depression. This finding will provide a new framework for the development of diagnostic methods, treatments, and preventive strategies against late-onset depression.

Biological and social predictors of long-term geriatric depression outcome

OBJECTIVE

In this study, we examined 204 older depressed individuals for up to 64 months to determine factors related to depression outcome. We hypothesized that both presence of vascular brain lesions seen on baseline magnetic resonance imaging (MRI) scans and lower baseline social support measures would be related to worse depression outcome.

METHOD

At study entry, all subjects were at least 59 years old, had a diagnosis of major depression, and were free of other major psychiatric illness and primary neurological illness, including dementia and stroke. Depression was diagnosed via structured interview and clinical assessment by a geriatric psychiatrist who completed a Montgomery Asberg Depression Rating Scale (MADRS) to determine severity of depression. Subjects provided self-report data on social support variables and ability to perform basic and instrumental activities of daily living (ADL, IADL). All subjects agreed to have a baseline standardized MRI brain scan. Ratings of severity of hyperintensities were determined for the periventricular white matter, deep white matter, and subcortical gray matter by two readers who decided by consensus. Treatment was provided by geropsychiatrists following clinical guidelines. Using mixed models to analyze the data, we determined the effect of a variety of demographic, social and imaging variables on the trajectory of MADRS score, the outcome variable of interest.

RESULTS

MADRS scores decreased steadily over time. In a final HLM model, in which time since entry, a baseline time indicator, age, gender, education and Mini-mental State Examination score were controlled, subjective social support, instrumental ADL impairment, subcortical gray matter severity, and the interactions of time with social network and with subcortical gray matter lesions remained significantly associated with MADRS score.

CONCLUSIONS

Both social and biological factors at baseline are associated with longitudinal depression severity in geriatric depression.

Establishing diagnostic criteria for vascular depression

We have proposed a subtype of vascular depression with two key elements: (1) presence of major depression and (2) presence of cerebrovascular disease on neuroimaging. Future studies are needed to refine these diagnostic criteria. There must be a consensus as to whether requiring major depression criteria is acceptable, or possibly too stringent. There are several methodological issues regarding cerebrovascular disease, including defining severity and thresholds, importance of location and system of assessment. Once agreement is reached on a working diagnosis of vascular depression, researchers will be in a position to estimate prevalence of the disorder, determine conditions that represent risk factors, and examine important outcomes in patients with vascular depression.

Regional cerebral blood flow in depressed patients with white matter magnetic resonance hyperintensity

BACKGROUND

Functional neuroimaging studies have consistently demonstrated decreased regional cerebral blood flow (rCBF) or metabolism in the frontal lobe, temporal lobe, or anterior cingulate gyrus of depressed patients. On the other hand, white matter hyperintensity as defined by magnetic resonance imaging (MRI) has been the most consistently replicated finding in structural neuroimaging studies on depression; however, these functional and structural neuroimaging findings of depression have not been well integrated. We aimed to clarify the possible associations of MRI-defined subcortical hyperintensities with rCBF changes in depressed patients.

METHODS

Twelve depressed patients with subcortical hyperintensities defined by MRI, 11 depressed patients without MRI hyperintensities, and 25 healthy volunteers underwent 99mTc ECD SPECT. Group comparisons of their rCBF and correlation analysis between MRI hyperintensity and rCBF in patients were performed with a voxel-based analysis using statistical parametric mapping (SPM) software.

RESULTS

Depressed patients showed decreased rCBF compared with control subjects in the frontal lobe, temporal lobe, and anterior cingulate gyrus whether subcortical hyperintensity existed or not; however, the patients with MRI hyperintensity showed decreased rCBF in the thalamus, basal ganglia, and brainstem in addition to cortical areas. Further, the score for white matter hyperintensity correlated negatively with rCBF in subcortical brain structures, including the thalamus and right basal ganglia.

CONCLUSION

Our study indicates that depressed patients with MRI hyperintensities may have dysfunction in subcortical brain structures in addition to dysfunction in the fronto-temporal cortical structures.

Development of a semi-automated method for quantification of MRI gray and white matter lesions in geriatric subjects

Brain magnetic resonance imaging (MRI) allows for quantitative assessment of hyperintense foci, which are seen with aging and various diseases. These foci, considered to represent lesions, are important in the study of various psychiatric illnesses, including depression. Few quantitative measures have been developed for such research. The goal of the current study was to develop a reliable and efficient method for quantifying the volumes of gray and white matter lesions in MRI scans of the elderly. Interrater reliability was determined by repeat lesion measures on 16 scans. Semi-automated segmentation was performed that identified potential lesions, and then lesions were manually selected based upon detailed anatomic criteria. The lesion quantification procedure took between 25 and 45 min per scan. Reliability intraclass correlation coefficients (ICCs) were 0.99 for both gray and white matter lesions. Volumetric results were found to be moderately correlated with previous lesion ratings (r-values between 0.37 and 0.62, P<0.0001). Among the 700 scans processed with this method, lesion volumes ranged from 0 to 7.3 ml for gray matter, and from 0.4 to 96.8 ml for white matter. Our method proved to be efficient and reliable for quantifying lesions in MRI scans of the elderly.

Anatomic location and laterality of MRI signal hyperintensities in late-life depression

OBJECTIVES

Evidence is mounting linking cerebrovascular disease with the development of major depression in the elderly. Lesions in both white and gray matter have been associated with geriatric depression. In addition, the literature on poststroke depression suggests that left-sided lesions are associated with depression. We sought to examine the severity and location of white- and gray-matter lesions in a group of elderly depressives and nondepressed control subjects.

METHOD

115 depressed patients (69 with late onset, 46 with early onset) and 37 controls, all over age 45, received magnetic resonance imaging (MRI). Semiquantitative severity ratings and quantitative measurements of number and size of MRI hyperintensities were obtained, and groups were compared using Cochran-Mantel-Haenszel (CMH) analyses and repeated-measures analyses of covariance adjusting for age.

RESULTS

Late-onset depressed patients had more severe hyperintensity ratings in deep white matter than early-onset patients and controls. Late- and early-onset patients had more severe subcortical gray-matter hyperintensities (particularly in the putamen) compared with controls. Left-sided white-matter lesions were significantly associated with older age of depression onset, whereas right-anterior white matter and left-subcortical lesions (particularly in the putamen) were associated with melancholia in the depressed group.

CONCLUSION

These findings extend previous reports of an association between cerebrovascular disease and depression, as well as recent studies showing lateralized lesion involvement in geriatric depression. Such vascular pathology may disrupt neural pathways involved in affective processing and the maintenance of a normal mood and psychomotor state.

A controlled study of MRI signal hyperintensities in older depressed patients with and without hypertension

OBJECTIVES

To compare the frequency/severity of signal hyperintensities--likely markers of cerebrovascular disease--in the subcortical gray and deep white matter on magnetic resonance imaging (MRI) scans of brains of hypertensive and normotensive older depressed and nondepressed comparison subjects.

DESIGN

Between-groups comparison of cross-sectional MRI data employing analyses of covariance controlling for the effects of age, gender, and height.

SETTING

A comprehensive inpatient-outpatient geriatric psychiatry service in a university hospital.

PARTICIPANTS

Nondemented older depressed (n = 81) and nondepressed comparison (n = 70) subjects divided into four groups (hypertensive depressed (n = 40), hypertensive normals (n = 21), normotensive depressed (n = 41), normotensive normals (n = 49)).

MEASUREMENTS

Signal hyperintensities were rated on T-2 weighted MRI scans blind to patient diagnoses employing two standardized hyperintensity rating systems (Fazekas, Boyko).

RESULTS

Hypertensive depressives had significantly more- severe hyperintensity ratings in both subcortical gray and deep white matter than did normotensive depressives and controls (P < .05) and significantly more-severe hyperintensity ratings only in subcortical gray matter (P < .05) than did hypertensive controls. Hypertensive controls had significantly more-severe ratings in deep white matter than either normotensive group (P < .05).

CONCLUSIONS

Findings suggest a relationship between deep white matter hyperintensities and hypertension (regardless of depressive state), and a particular role of subcortical gray matter hyperintensities (possibly interacting with more-severe deep white matter lesions) in older depressed hypertensives, as compared with older depressed normotensives of similar ages and severity of depression. These data support possible heterogeneous pathogenic contributions in late-life depression subgroups, one of which appears to be influenced by cerebrovascular disease.

A magnetic resonance imaging study of thalamic area in adolescent patients with either schizophrenia or bipolar disorder as compared to healthy controls

The purpose of this study was to compare thalamic size in adolescent patients with either schizophrenia or bipolar disorder and healthy controls. T2-weighted axial magnetic resonance images were used to manually define the area of the thalamus for 20 schizophrenia patients, 15 bipolar patients and 16 normal control subjects, all of whom were adolescents. Two orthogonal planned contrasts were tested: Contrast 1, patients with schizophrenia vs. patients with bipolar disorder; and Contrast 2, both patient groups taken as a single group compared to controls. Contrast 1 was not statistically significant for right or left thalamic area. Contrast 2 was statistically significant and indicated reductions in thalamic area in the patients as compared to controls. The same pattern of results emerged after adjustment for total brain volume. Our results indicate that thalamic abnormalities reported in adult schizophrenic and bipolar patients are also observed in adolescent patients. Our findings also add to the evidence implicating the thalamus in the pathophysiology of schizophrenia and bipolar disorder.

Candidate neuroanatomic substrates of psychosis in old-aged depression

1. The authors investigated the candidate neuroanatomic substrates underlying delusional thought disorder in old-aged depressed patients by using magnetic resonance imaging (MRI), and examined the relationship between volumes for individual brain structures and clinical correlates of particular relevance to depression: executive cognitive impairment and global severity of depression. 2. MR morphometry was performed on nineteen deluded depressed patients and 26 non-deluded depressed patients, all older than 55 years of age. Subjects were administered a neuropsychological test battery and measures of depression. 3. The absolute volume of prefrontal cortex (PFC) was smaller in the deluded depressed group than in non-deluded depressed group (131.79 +/- 37.26 ml vs. 152.65 +/- 26.13 ml, p = 0.03); a difference that was statistically significant even after adjusting for the effect of whole brain volume (p = 0.01). No group differences were observed in the volumes of the basal ganglia, the temporal lobes, the superior temporal gyri, the amygdala-hippocampal complex, the lateral ventricles, or whole brain. The relative volume of PFC correlated inversely and significantly with the index of Wisconsin Card Sorting Test (WCST) performance (r = -0.76, p < 0.01) in depressed patients. 4. PFC may be one of the candidate neuroanatomic substrates underlying delusional thought disorder in old-aged depression.

Hyperintense lesions on magnetic resonance images in bipolar disorder

BACKGROUND

To examine the magnetic resonance (MR) images of bipolar patients across a wide age range for the presence of hyperintense lesions compared to age- and gender-matched control subjects.

METHODS

Consecutive admissions to a mood disorders unit over a 2-year period were evaluated retrospectively for the presence of bipolar disorder by DSM-III-R criteria and whether they received an MR scan. Bipolar patients (n = 70, mean age = 49.9 +/- 19.7 years) were age- and gender-matched to control subjects (n = 70, mean age = 53.2 +/- 18.1 years) and the MR scans were rated to assess for the presence of hyperintensites.

RESULTS

Compared to control subjects, the bipolar patients demonstrated hyperintense lesions in the subependymal region, subcortical gray nuclei, and the deep white matter.

CONCLUSIONS

Hyperintense lesions in bipolar patients are found in both the subcortical white matter and gray nuclei and may play an important role in the etiology of bipolar illness.

Neuropsychological functioning and MRI signal hyperintensities in geriatric depression

OBJECTIVE

The purpose of this study was to examine the relationship between signal hyperintensities--a probable marker of underlying pathology--on T2-weighted magnetic resonance brain scans and neuropsychological test findings in elderly depressed and normal subjects.

METHOD

Elderly subjects with a DSM-III-R diagnosis of major depression (N=41) and normal elderly comparison subjects (N=38) participated in a magnetic resonance imaging study (1.0-T) of signal hyperintensities in periventricular, deep white matter, and subcortical gray matter. Hard copies of scans were rated in random order by research psychiatrists blind to diagnosis; the modified Fazekas hyperintensity rating scale was used. Cognitive performance was independently assessed with a comprehensive neuropsychological battery. Clinical and demographic differences between groups were assessed by t tests and chi-square analysis. Relationships between neuropsychological performance and diagnosis and hyperintensities and their interaction were analyzed by using analysis of covariance, with adjustment for age and education.

RESULTS

Elderly depressed subjects manifested poorer cognitive performance on several tests than normal comparison subjects. A significant interaction between hyperintensity location/severity and presence/absence of depression on cognitive performance was found: depressed patients with moderate-to-severe deep white matter hyperintensities demonstrated worse performance on general and delayed recall memory indices, executive functioning and language testing than depressed patients without such lesions and normal elderly subjects with or without deep white matter changes.

CONCLUSIONS

Findings validate cognitive performance decrements in geriatric depression and suggest possible neuroanatomic vulnerabilities to developing particular neuropsychological dysfunction in depressed subjects.

On the efficiency of stereologic volumetry as commonly implemented for three-dimensional digital images

The aim of the study was to demonstrate, for certain ideal shapes (right cylinders) and for representative neuroanatomical images, that stereologic volumetry of three-dimensional images is more efficient when the sampling grid is placed randomly on each cross-section rather than identically across sections. As an example, the special case of mathematical right cylinders is presented, and an informal proof is provided. For neuroanatomical images, a custom computer program estimated volume with either the fixed- or random-grid method, using the same cross-sectional slices and first-slice test grid position for each method. The slice spacing, grid size, and starting grid position were randomly varied within practical constraints for 100,000 trials in each image. For right cylinders, the random-grid method is always more efficient than the fixed-grid method. For the neuroanatomic images tested, relative variance was up to three times higher for the fixed-grid method than for the random-grid method, especially for test grids with few grid intersections ('hits') per section. With the random-grid method, relative variance is primarily dependent on the total number of hits rather than on the distribution of hits per section. Implementation of the random-grid method for stereologic volumetry in three-dimensional images should in general improve sampling efficiency.

Magnetic-resonance morphometry in patients with major depression

Magnetic-resonance morphometry performed on 72 patients with major depression compared with 38 control subjects replicated previously reported, statistically significant reductions in the volumes of the caudate (P < 0.03) and putamen (P < 0.05) in depressed patients. Borderline statistical significance was observed for whole-brain (P < 0.07) and frontal volume (P < 0.10) in a subsample of 32 patients matched on age and sex with 32 control subjects, whereas statistical significance was observed for the full sample (P < 0.007 and P < 0.03, respectively). Chronological age was related to volume of the frontal lobes (P < 0.0002), caudate (P < 0.0001), putamen (P < 0.008), thalamus (P < 0.002), cerebellum (P < 0.007), lateral ventricles (P < 0.0001), and ratios of [whole brain]/[whole brain + cerebrospinal fluid (CSF)] (P < 0.0001) and [frontal]/[frontal + CSF] (P < 0.0001). Age of first depressive episode was related to putamen volume after accounting for chronological age (R2= 0.16, P < 0.005), and a correlation of 0.26 (P < 0.04) was observed between caudate volume and global mental status. Results are in accord with previous reports of basal-ganglia abnormalities in depressed patients and support the role of subcortical structures in mediating affective disorder.

Depression in the elderly: a review

Although there is a plethora of literature regarding depression in the elderly, recognition of its existence remains a primary problem. Recognizing depression is paramount in the elderly. There is significant mortality and morbidity associated with elderly depression. The assumption that depression is a normal aging process must be changed. This should be done by educating the public and the practitioner. Appropriate screening tools should be administered on a regular basis regardless of the reason the elderly person is seeking care. These would include the Mini-Mental State Examination and a depression scale of the practitioner's choice. Baseline information should be gathered in order to provide data for further examination and continuity of care. This would be beneficial to determine the presence of a decline in either mental or cognitive states. There is evidence of gaps in the research related to depression in the elderly. Studies related to cognition and depression have contradictory results. Various limitations in the studies, such as sample size and the presence of cognitive impairment prior to the study, could account for this. Replication of these studies and further research in cognition and depression in the elderly is warranted.

Volumetric analysis of white matter, gray matter, and CSF using fractional volume analysis

Quantitative cerebral tissue volumes may be useful for an objective assessment of pathological changes in brain. Accurate determination of tissue volumes is complicated, however, by the partial volume averaging (PVA) effect. We have, therefore, developed a new pulse sequence that minimizes the PVA through the use of inversion-recovery (IR) and double inversion-recovery (DIR) techniques. This pulse sequence simultaneously acquires four different sets of images to provide the necessary information for volumetric analysis and reduces potential spatial misregistration of images due to patient motion. The image sets acquired from the proposed pulse sequence are 1) gray matter visible, 2) white matter visible, 3) FLAIR, and 4) fast spin-echo proton-density weighted images. An algorithm has been implemented to correct for differential T1-weighting and for tissue quantitation.

Metabolic brain mapping in Alzheimer's disease using proton magnetic resonance spectroscopy

Alzheimer's disease (AD) is a progressive disorder associated with disruption of neuronal function and neuronal loss. N-acetylaspartate (NAA) is a marker of neuronal content and can be assessed using proton (1H) magnetic resonance spectroscopy (MRS). We utilized 1H-MRS (two-dimensional chemical-shift imaging) to assess amplitudes and areas of NAA, as well as choline moieties (Cho), creatine (Cr) and myo-inositol (mI), in 15 AD patients compared with 14 control subjects. Voxels were classified as predominantly cortical gray matter (CGM), subcortical gray matter (SGM), or white matter (WM). Compared with control subjects, AD patients exhibited decreased NAA/Cho and NAA/Cr amplitudes, whereas an increase was observed in Cho/Cr and in amplitude ratios involving mI. Area ratios were significant in the same direction for NAA/Cho, NAA/Cr, mI/Cr and mI/NAA. No significant effects of tissue type were observed; however, significant group x tissue type interactions were noted for Cho/Cr and mI/Cr amplitudes. Our study confirms that 1H-MRS can identify distinct physicochemical alterations in AD patients, reflecting membrane changes and diminished neuronal function. These alterations can be used as longitudinal markers for the disease.

Structural changes in the brain of patients with bipolar affective disorder by MRI: a review of the literature

1. Current literature was searched to evaluate the use of magnetic resonance imaging in patients with bipolar disorder. 2. The presence of white matter hyperintensities, differences in temporal lobe and hippocampal structures, and ventricular enlargement in patients with bipolar disorder was assessed. 3. Further use of MRI in patients with bipolar disorder is reviewed.

The anatomy of mood disorders--review of structural neuroimaging studies

The structural neuroimaging findings in mood disorders were reviewed, to evaluate evidence for a neuroanatomic model of pathophysiology, involving the prefrontal cortex, the basal ganglia, the amygdala-hippocampus complex, thalamus, and connections among these structures. Global atrophy is not consistently found. The best replicated finding is an increased rate of white matter and periventricular hyperintensities. A smaller frontal lobe, cerebellum, caudate, and putamen appear present in unipolar depression. A larger third ventricle, and smaller cerebellum and perhaps temporal lobe appear present in bipolar disorder. These localized structural changes involve regions that may be critical in the pathogenesis of mood disorders. Generalized and localized anatomic alterations may be related to age or vascular disease. The clinical and biological correlates of these changes need to be investigated to allow development of a more complete model of pathophysiology of mood disorders.

Magnetic resonance imaging of Alzheimer's disease

1. Although dementia is caused by a heterogeneous group of diseases and pathologic states, Alzheimer's disease is the largest cause, estimated to account for 50 to 75% of all dementias. 2. Unfortunately, confirmation of Alzheimer's disease (AD) requires postmortem histologic confirmation; clinical diagnosis prior to death remains one of exclusion. 3. A large number of structural and volumetric MRI studies have noted anatomic and structural changes accompanying AD, including variable degrees of general cortical atrophy. 4. A classic feature reported by many MRI studies is hippocampal and temporal lobe atrophy. 5. White matter hyperintensities on MRI are common, especially in late onset AD although their significance is still controversial. 6. This article reviews the contribution of magnetic resonance to imaging the neuropathologic changes of AD, discussing both advantages and limitations, and summarizing the major findings.

MRI changes in schizophrenia in late life: a preliminary controlled study

The aim of this pilot study was to compare cerebral changes on magnetic resonance imaging (MRI) scans in elderly schizophrenic subjects with those in psychiatric and normal control subjects. We compared the MRIs of 19 subjects with schizophrenia, 19 age- and gender-matched subjects with recurrent major depression, and 19 age- and gender-matched nonpsychiatric control subjects. Deep white matter hyperintensities (DWMH) in right posterior regions were significantly more prominent in the schizophrenic group than in the two comparison groups. Total ratings of MRI abnormalities were significantly related to age in both the normal control and schizophrenic groups, but not in the depressive group. Age of onset was positively associated with total ratings in the depressive group, but not in the schizophrenic group. Thus, a subset of elderly patients with schizophrenia appear to have cerebral white matter abnormalities; such abnormalities may not be confined to late-onset schizophrenia. Systematic MRI studies of early- and late-onset schizophrenia in late life are needed to resolve this question.

Relative accuracy and reproducibility of regional MRI brain volumes for point-counting methods

Volumetric magnetic resonance imaging (MRI) methods for the measurement of various neuroanatomical regions are of great interest in studies of neuropsychiatric disorders. Both manual and semiautomated methods have been developed. Manual methods include tracing and point counting. Point counting methods are widely used in post-mortem and microscopy studies. Point counting has been well validated for these purposes. In this article, we report in a series of separate studies the accuracy and reproducibility of point-counting methods. Absolute accuracy was evaluated with a spherical phantom. Accuracy and time efficiency were subsequently assessed with an anatomically realistic phantom and various size grids. The point-counting method was also compared to a tracing method. Finally, the reproducibility of the point-counting method for the caudate and putamen was evaluated on four subjects in a test-retest experiment. These studies provide an estimate of the accuracy and time efficiency of point-counting methods. The test-retest reliability was also high for both caudate and putamen. Findings suggest that point counting is a reliable and efficient method for estimating volumes.