Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Structural MRI”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 793 records · Page 44Linked to original sources
PubMed1985

Presentation of bilateral thalamic infarction on CT, MRI and PET.

Paramedian thalamic structures and part of the upper midbrain are frequently supplied by posterior thalamoperforating arteries originating from one common trunk. Local impairment of flow entails a bilateral more or less symmetric thalamic infarction with varying involvement of the midbrain. Diagnosis usually can neither be firmly established on clinical grounds nor by angiography alone. In the present series of four patients the two cases observed before the CT era were diagnosed correctly only at autopsy. Only one patient presented the classical syndrome of hypersomnia, thalamic dementia, and oculomotor nerve paralysis, while in the others clinical signs were probably masked by serious impairment of consciousness. In two cases X-ray computed tomography and magnetic resonance tomography (one case) afforded precise definition of infarct localization and size. Infarction in the described terminal vascular supply territory may be detected more often by these modern diagnostic techniques than anticipated from previous clinico-pathological experience as the underlying cause of coma in the elderly-a group of patients at particular risk for low-flow states. Positron emission tomography repeat studies with 18F-2-fluorodeoxyglucose (one case) revealed complex disturbances of brain energy metabolism; correlative analysis of clinical function and metabolic patterns during the course of the disease may not only advance individual prognostication but also contribute to the understanding and localization of brain function.

Adult↗
PubMed2002

Concentric structure of thalamic lesions in acute necrotizing encephalopathy.

Acute necrotizing encephalopathy of childhood (ANE) is characterized by multiple, symmetrical brain lesions affecting the bilateral thalami, putamina and cerebral white matter, which often show a concentric structure on CT and MRI. To reveal the pathological substrate of this finding, comparison was made between CT and necropsy findings of three fatal cases of ANE. Cranial CT demonstrated a concentric structure of the thalamocerebral lesions in one patient who died 3.5 days after the onset of encephalopathy, but not in the other two patients who died within 30 h. Neuropathological examination of postmortem brains revealed laminar changes of vascular and parenchymal pathology in all the cases. Excessive permeability of blood vessels and resultant vasogenic edema became more prominent with increasing depth from the cerebral surface. The deep portion of the lesions showed severe perivascular hemorrhage, accounting for the central high density on the CT images of one patient.

Child Welfare↗
PubMed2004

Localized volume reduction in prefrontal, temporolimbic, and paralimbic regions in schizophrenia: an MRI parcellation study.

Functional and structural abnormalities of the anterior cingulate gyrus (ACG) in patients with schizophrenia have been repeatedly reported. However, one remaining issue is whether gray matter volume reduction in ACG exists to an extent comparable with, or even in excess of, that in other prefrontal and temporolimbic regions. High-spatial-resolution magnetic resonance imaging was performed on patients with schizophrenia (n=27) and on age-, gender-, and parental socioeconomic-status-matched healthy control subjects (n=27). After the gray and white matter were semiautomatically segmented, whole prefrontal and temporal lobes were manually parceled into 15 subregions-by-two hemispheres (30 regions of interest) constituting seven prefrontal gray matter regions, six temporal gray matter regions, the prefrontal white matter, and the temporal white matter. Compared with healthy subjects, schizophrenic patients showed significant gray matter volume reduction in the bilateral ACG, this being the largest effect size (left, 0.84; right, 0.56) among all the regions examined. There were also significant gray matter volume reductions in the bilateral posterior STG, bilateral inferior frontal gyrus, left posterior amygdala-hippocampal complex (mostly hippocampus), and the left insula. These results suggest that gray matter volume reductions in the ACG are prominent among prefrontal and temporolimbic regions in patients with schizophrenia. These findings indicate the importance of ACG abnormalities in the pathophysiology of schizophrenia.

Adult↗
PubMed2000

Apolipoprotein E genotype and hippocampal asymmetry in Alzheimer's disease: a volumetric MRI study.

Asymmetry of brain structures is common to many species and is even present in utero. Some developmental, pathological, and dementing diseases are associated with alterations in normal anatomical asymmetries. Anatomical asymmetries, however, have been only superficially studied in Alzheimer's disease. Recent evidence indicates that the allele epsilon4 of the apolipoprotein E (ApoE), a well known risk factor for Alzheimer's disease, might play a part in determining some brain morphological changes both in normal carriers and in patients with Alzheimer's disease. This study evaluated the effect of the ApoE genotype on hippocampal asymmetry in patients with Alzheimer's disease carrying 0, 1, and 2 copies of the allele. Volumetric right-left differences of the hippocampi were computed in 28 right handed patients with Alzheimer's disease (14 -/-, 9 epsilon4/-, and 5 epsilon4/4) and 30 controls without detectable cognitive deficit. In controls, the right hippocampus was larger than the left, whereas in patients with Alzheimer's disease this asymmetry was progressively reduced with increasing gene dose of the epsilon4 allele, and the asymmetry was reversed in the epsilon4/4 Alzheimer's disease group. The mean right-left volume differences were: 1.2, 0.7, 0.2, and -1.0 in controls, -/-, epsilon4/-, and epsilon4/4 patients, respectively (sex adjusted p for trend=0.017). The data indicate a dose dependent effect of the ApoE epsilon4 allele on hippocampal volume asymmetry in Alzheimer's disease.

Aged↗
PubMed2005

A wavelet-based statistical analysis of FMRI data: I. motivation and data distribution modeling.

We propose a new method for statistical analysis of functional magnetic resonance imaging (fMRI) data. The discrete wavelet transformation is employed as a tool for efficient and robust signal representation. We use structural magnetic resonance imaging (MRI) and fMRI to empirically estimate the distribution of the wavelet coefficients of the data both across individuals and spatial locations. An anatomical subvolume probabilistic atlas is used to tessellate the structural and functional signals into smaller regions each of which is processed separately. A frequency-adaptive wavelet shrinkage scheme is employed to obtain essentially optimal estimations of the signals in the wavelet space. The empirical distributions of the signals on all the regions are computed in a compressed wavelet space. These are modeled by heavy-tail distributions because their histograms exhibit slower tail decay than the Gaussian. We discovered that the Cauchy, Bessel K Forms, and Pareto distributions provide the most accurate asymptotic models for the distribution of the wavelet coefficients of the data. Finally, we propose a new model for statistical analysis of functional MRI data using this atlas-based wavelet space representation. In the second part of our investigation, we will apply this technique to analyze a large fMRI dataset involving repeated presentation of sensory-motor response stimuli in young, elderly, and demented subjects.

Adult↗
PubMed2002

Ex vivo high-resolution magnetic resonance imaging of the brain in Joubert's syndrome.

This study employs ex vivo high-resolution magnetic resonance imaging (MRI) to examine anatomic structures in an intact brain of a child with Joubert's syndrome. Several of the specific hindbrain malformations associated with Joubert's syndrome are well resolved with ex vivo MRI, including the "molar tooth sign," which arises from enlarged and maloriented superior cerebellar peduncles, hypoplastic vermis, and deepening of the interpeduncular fossa. Superior resolution was achieved compared with that of in vivo MRI and included visualization of the inferior olives. One high-resolution study also showed that the decreased width of the brainstem isthmus is probably caused by failure of superior cerebellar peduncles to cross the midline at that level. The results of this study suggest that high-resolution MRI may be useful in screening the brainstem for malformations that can be studied histologically in a much more targeted fashion.

Child, Preschool↗
PubMed2006

Reduced hypothalamic gray matter in narcolepsy with cataplexy.

OBJECTIVES: Narcolepsy with cataplexy is associated with a loss of hypocretin. The question is, if there is an autoimmune or neurodegenerative process selectively killing the hypothalamic hypocretin-containing neurons or if these cells survive but fail to produce hypocretin. To support one of these hypothesis we aimed to detect structural changes in the hypothalamus of narcoletic patients. MATERIALS AND METHODS: Nineteen narcoleptic patients were compared to 16 healthy controls. We used voxel-based morphometry (VBM), an unbiased MRI morphometric method with a high sensitivity for subtle changes in gray and white matter volumes to investigate hypothalamic region in this condition. RESULTS: Classical MRI protocol revealed no structural abnormalities, but using VBM we found significant reduction in hypothalamic gray matter volumes between patients and controls. CONCLUSIONS: VBM showed hypothalamic gray matter loss in narcolepsy with cataplexy. This suggest that functional abnormalities of hypocretin neurons in narcolepsy are associated with structural changes of hypothalamus.

Adult↗
PubMed2004

MR visualization of the inner ear structures: comparison of 1.5 Tesla and 3 Tesla images.

AIM OF THE STUDY: To compare high resolution MRI examinations of inner ear structures at 1.5 T and at 3 T. METHOD: Temporal bones were measured bilaterally in 3 healthy volunteers in a 1.5 T and in a 3 T MR-scanner using the respective one channel head coil (quadrature detection) of the manufacturer. The same steady-state gradient echo sequence (3D-CISS) was employed at a voxel size of 0.4 x 0.4 x 0.4 mm(3). The signal-to-noise ratio (SNR) was determined quantitatively. RESULTS: An SNR of 8 could be achieved for the measurements at 3 T in 7:37 min. The SNR at 3 T was, on average, a factor of 1.34 higher than that at 1.5 T despite the fact that the excitation angle had to be drastically reduced (alpha = 42 degrees instead of alpha = 70 degrees at 1.5 T) due to the limit of the specific absorption rate (SAR). DISCUSSION: The MR representation of the inner ear is clearly improved at 3 T. To obtain the same SNR at 1.5 T approximately the double measuring time would be required, connected with reduced patient comfort and an increased risk for a displacement of the head during the high resolution measurement.

Cochlea↗
PubMedDate not supplied

Magnetic resonance of the temporomandibular joint: experience at an Italian university center.

AIM: The aim of this investigation was to suggest criteria in order to evaluate magnetic resonance imaging (MRI) of the temporomandibular joint (TMJ). Such criteria have been discussed on the basis of our experience at the Section of Prosthetic Dentistry, Department of Neurosciences, University of Pisa. METHODS: The study sample was constituted by 135 patients. All subjects underwent bilateral MRI of the TMJs to evaluate disc structure and position, bony structure abnormalities, joint effusion localization and entity. RESULTS: MRI allowed depiction of the articular disc in 98.9% of the TMJs, showing a normal disc structure in 91.1% of the cases and abnormal in 7.7%. The disc-condyle relationship was normal in 46.6% TMJs, while a disc displacement with reduction was revealed in 35.5% cases, a disc displacement without reduction in 16.7% and a posterior disc displacement in 1.5% joints. In the coronal images, the disc was positioned lateral to the condyle in 8.9% of the TMJs and medial in 6.7%. Osseous abnormalities have been found in 177 joints (65.5%), with cases of bony flattening (condyle and/or tuberculum), erosions, subchondral cysts, osteophytosis and sclerosis. T2 sequences showed effusion in 26.7% of the TMJs. CONCLUSIONS: These findings suggest that standardized methodology application and well-defined criteria can facilitate MR imaging observations and interpretation as well as the diagnosis of intra-articular pathologies.

Adolescent↗
PubMed2006

Imaging study scores for ankylosing spondylitis.

Scoring systems have been developed for radiographs and magnetic resonance imaging (MRI) in patients with ankylosing spondylitis (AS). Radiographic scores focus on chronic structural alterations, which occur slowly and show little sensitivity to change in the short-term. Recent clinical studies used the modified Stoke ankylosing spondylitis spine score (mSASSS), which evaluates the cervical and lumbar spine. TNF antagonists were found to modify the mSASSS, indirectly supporting a structural effect of these agents. MRI using specific sequences is a potent tool for evaluating inflammation, most notably at the spine. MRI has proved sensitive to change in patients taking TNF antagonists. An outcome measures in rheumatology clinical trials (OMERACT) task force is working on standardizing MRI scores for the spine and sacroiliac joints.

Arthrography↗
PubMed2003

Can we rely on magnetic resonance imaging when evaluating unstable atlantoaxial subluxation?

OBJECTIVES: To examine whether functional radiography and functional magnetic resonance imaging (MRI) are equally efficient in detecting the extent of unstable anterior atlantoaxial subluxation (aAAS) in rheumatic patients. METHODS: 23 patients with unstable aAAS (diagnosed by functional radiography) were examined by functional MRI because of a neck symptom. Twenty two patients had rheumatoid arthritis and one had juvenile idiopathic arthritis. aAAS was diagnosed if the anterior atlantoaxial diameter (AAD) was >3 mm and was considered unstable if the AAD differed by >2 mm between flexion and extension radiographs. The AAD was measured from radiographs (flexion and extension) and MRI images (flexion and neutral). RESULTS: The extent of aAAS during flexion measured by radiography was greater than that found by MRI in all 23 patients (mean difference 3 mm (95% confidence interval 2 to 4)). In four (17%) patients flexion MRI could not demonstrate aAAS detected by radiography. The difference between the AAD measurements during flexion by these two methods was substantial (that is, >or=4 mm) in nine (39%) cases. Severe aAAS (>or=9 mm) was seen in 15 (65%) patients by functional radiography and in four (17%) by functional MRI. CONCLUSIONS: The magnitude of aAAS was often substantially smaller when measured by functional MRI rather than by functional radiography. Thus one cannot rely on the result of functional MRI alone; functional radiographs are needed to show the size of unstable aAAS. The maximal extent of the subluxation must be taken into account when the possible compression of neural structures is evaluated by MRI.

Adult↗
PubMedDate not supplied

Determination of rat heart morphology and function in vivo in two models of cardiac hypertrophy by means of magnetic resonance imaging.

Quantitative magnetic resonance imaging (MRI) was applied to assess structural and functional parameters of the rat heart in vivo. Using ECG and respiratory triggering, MR images were obtained at different time points during the cardiac cycle. This allowed accurate determinations of the left ventricular (LV) mass, wall thickness, LV end-systolic and end-diastolic volumes, stroke volume, and ejection fraction. LV mass determined by MRI showed and excellent linear correlation with post mortem gravimetric determination of LV weight. MRI was then used to examine the pathophysiological changes in two models of LV hypertrophy. In one group of animals the aortic arch was banded to an outer diameter of 1.0 mm to elicit a pressure overload on the LV. A second group was subjected to a volume overload due to graded disruption of the aortic valve. Although both models exhibited a similar degree of LV hypertrophy as shown by the LV weight/body weight ratio, important functional and structural differences were revealed by MRI. Aortic stenosis resulted in an increase in wall thickness, whereas stroke volume and ejection fraction did not differ compared to control animals. In contrast, aortic valve insufficiency did not affect LV wall thickness, however, LV chamber volume as well as stroke volume were markedly increased. Ejection fraction was significantly reduced in these animals. In conclusion, MRI allows the reliable in vivo determination of important structural and functional parameters of hearts in small rodents.

Animals↗
PubMed1990

Brain imaging in acquired immunodeficiency syndrome dementia complex.

Human immunodeficiency virus (HIV) infections are accompanied by many different types of neurological complications. Opportunistic infections and neoplasms, particularly lymphoma, are often an underlying cause for these complications in patients with acquired immunodeficiency syndrome (AIDS). Frequently, these can be detected by cerebrospinal fluid (CSF) examination, double-dose contrast transmission computed tomography (CT), and/or magnetic resonance imaging (MRI). It has become apparent that the HIV itself is responsible for a significant percentage of neurological disease in the HIV-seropositive individual. The onset may be subtle and may occur before the onset of frank immunosuppression. Diagnosis of HIV encephalitis or AIDS dementia complex (ADC) is complicated by the frequent coexistence of opportunistic infections. Structural neuroimaging (CT or MRI) shows atrophy and in some case white matter abnormalities, but imaging-pathological correlation suggests that these modalities are relatively insensitive to the presence of HIV brain infection. Functional neuroimaging, both 18fluorodeoxyglucose positron emission tomography (PET) for evaluation of glucose metabolism and 123I iodoamphetamine or 99mTc-HMPAO single-photon emission computed tomography (SPECT) for evaluation of cerebral perfusion, can demonstrate abnormalities in the subcortical gray matter structures and the cerebral cortex in patients with ADC. These abnormalities may be observed early in the course of ADC even when MRI is negative and the patient is relatively asymptomatic. Also, PET and SPECT may be useful to follow progression of the dementia or response to therapy.

AIDS Dementia Complex↗
PubMed2004

Middle and inferior temporal gyrus gray matter volume abnormalities in chronic schizophrenia: an MRI study.

OBJECTIVE: The middle temporal gyrus and inferior temporal gyrus subserve language and semantic memory processing, visual perception, and multimodal sensory integration. Functional deficits in these cognitive processes have been well documented in patients with schizophrenia. However, there have been few in vivo structural magnetic resonance imaging (MRI) studies of the middle temporal gyrus and inferior temporal gyrus in schizophrenia. METHOD: Middle temporal gyrus and inferior temporal gyrus gray matter volumes were measured in 23 male patients diagnosed with chronic schizophrenia and 28 healthy male subjects by using high-spatial-resolution MRI. For comparison, superior temporal gyrus and fusiform gyrus gray matter volumes were also measured. Correlations between these four regions and clinical symptoms were also investigated. RESULTS: Relative to healthy subjects, the patients with chronic schizophrenia showed gray matter volume reductions in the left middle temporal gyrus (13% difference) and bilateral inferior temporal gyrus (10% difference in both hemispheres). In addition, the patients showed gray matter volume reductions in the left superior temporal gyrus (13% difference) and bilateral fusiform gyrus (10% difference in both hemispheres). More severe hallucinations were significantly correlated with smaller left hemisphere volumes in the superior temporal gyrus and middle temporal gyrus. CONCLUSIONS: These results suggest that patients with schizophrenia evince reduced gray matter volume in the left middle temporal gyrus and bilateral reductions in the inferior temporal gyrus. In conjunction with findings of left superior temporal gyrus reduction and bilateral fusiform gyrus reductions, these data suggest that schizophrenia may be characterized by left hemisphere-selective dorsal pathophysiology and bilateral ventral pathophysiology in temporal lobe gray matter.

Adult↗
PubMed2003

Reduced left hemispheric white matter volume in twins with bipolar I disorder.

BACKGROUND: Although the heritability of bipolar I disorder (BPI) is high, few magnetic resonance imaging (MRI) studies of siblings of bipolar patients exist. We performed MRI brain scans on a nationwide sample of twins with BPI, as well as on their co-twins and a demographically balanced sample of control twin subjects, to detect any structural alterations related to the disorder and to the increased genetic risk. METHODS: The National Hospital Discharge Register, National Population Register, and Finnish Twin Cohorts were used to identify bipolar twins. Structured diagnostic interviews and MRI scans were obtained for 24 twins with BPI, 15 healthy co-twins, and 27 control twin subjects. RESULTS: Patients and co-twins showed a significant decrease in left hemispheric white matter volume. The disparity in patients was -16.1 cm(3) (95% confidence interval [CI] -26.6, -5.6) and in co-twins -11.3 cm(3) (95% CI -22.1, -0.4) compared with control twin subjects. No gray matter decrease was seen in patients or co-twins. CONCLUSIONS: The results of this first large-scale MRI study of twins with BPI, their co-twins, and appropriate control twin subjects, suggest that alterations of the left hemisphere white matter in BPI may reflect genetic factors predisposing to the disorder.

Adult↗
PubMed2001

Brain single-photon emission computed tomography and magnetic resonance imaging in Machado-Joseph disease.

BACKGROUND: Machado-Joseph disease (MJD) is one of the most frequently encountered spinocerebellar ataxias. However, few reports on brain single-photon emission computed tomographic (SPECT) imaging (BSI) with hexylmethylpropylene amineoxine labled with technetium Tc 99m and magnetic resonance imaging (MRI) have been performed for the evaluation of patients with MJD. OBJECTIVES: To investigate possible abnormalities with BSI and MRI in patients with MJD and to correlate these findings with the duration of symptoms; cerebellar, extrapyramidal, and pyramidal syndromes; and the molecular characteristics of the MJD mutation. PATIENTS AND METHODS: Twelve patients (8 males and 4 females [mean age, 39 years]) with genetically proven MJD were studied. The patients underwent BSI and MRI on the same day. Brain SPECT imaging was performed after an intravenous injection of 99mTc-hexylmethylpropylene amineoxine. The transaxial, coronal, and sagittal BSIs obtained were submitted to visual and semiquantitative analyses. Magnetic resonance imaging was obtained in a 2-T system with coronal, sagittal, transaxial, and 3-dimensional (volumetric) acquisitions. The volumes of the cerebellar hemispheres and vermis were calculated. Control groups for BSI (22 female and 20 male subjects [mean age, 33 years]) and MRI (13 female and 4 male subjects [mean age, 32.2 years]) were included for comparison. RESULTS: Correlation was observed between the perfusion abnormalities identified by visual analysis in the BSI with the structural abnormalities observed on MRI in the parietal lobes and vermis. Brain SPECT imaging identified (by visual analysis) more perfusion abnormalities in the inferior portion of the frontal lobes, mesial and lateral portions of the temporal lobes, basal ganglia, and cerebellar hemispheres. Magnetic resonance imaging identified more abnormalities in the pons and superior portions of the frontal lobes. Olivary atrophy was identified by MRI. Semiquantitative analysis showed a statistically significant difference of perfusion in the inferior and superior portions of the frontal lobes, lateral portion of the temporal lobes, parietal lobes, left basal ganglia, cerebellar hemispheres, and vermis when compared with the control group. A significant difference was noted between the vermis and cerebellar volumes on MRI when compared with the control group. A significant relationship was observed between the perfusion of the left parietal lobe (P =.05) and extrapyramidal syndrome. There was a tendency toward an inverse relationship between the duration of symptoms and the perfusion of the cerebellar hemispheres (rho = -0.37; P =.24) and volume of the vermis (rho = -0.30; P =.34); between the length of the expanded (CAG)n repeat and the perfusion of the left parietal lobe (rho = -0.32; P =.36), vermis (rho = -0.28; P =.43), and pons (rho = -0.28; P =.42). A direct association was observed between the length of the expanded (CAG)n repeat and the perfusion of the lateral portion of the right temporal lobe (rho = 0.67; P =.03). CONCLUSIONS: Brain SPECT imaging and MRI were capable of identifying subclinical abnormalities in individuals with MJD. These findings may be helpful for a better understanding of the pathophysiology of this disease.

Adult↗
PubMed2001

Ten year progressive ventricular enlargement in schizophrenia: an MRI morphometrical study.

Recent studies of the brain using magnetic resonance imaging (MRI) have suggested progressive structural changes in schizophrenics. However, those studies were conducted over periods of less than 5 years and thus lacked sufficient capacity to determine the course and nature of this process. In this study, MRI scans were obtained in 15 schizophrenics and 12 controls at baseline and after 4- and 10-year follow ups. Volumes of the lateral ventricles were measured. Patients were assessed by the Brief Psychiatric Rating Scale (BPRS) at the same two time points: at baseline and at 10-year follow up. After 10 years, a significant lateral ventricular enlargement was found in patients (mean percentage change: +22.9%) but not in controls (5.1%). Although our results are not in disagreement with the neurodevelopmental hypothesis, they do provide strong evidence that in schizophrenia progressive brain reduction occurs even in its chronic stage.

Adult↗
PubMed2006

Longitudinal brain magnetic resonance imaging study of the alcohol-preferring rat. Part I: adult brain growth.

BACKGROUND: The alcohol-preferring (P) rat, a Wistar strain selectively bred to consume large amounts of alcohol voluntarily, has been used as an animal model of human alcoholism for 3 decades. Heretofore, knowledge about brain morphology has been confined to postmortem examination. Quantitative neuroimaging procedures make it feasible to examine the potential longitudinal effects of alcohol exposure in vivo, while controlling modifying factors, such as age, nutrition, and exercise. To date, few imaging studies have considered what morphological changes occur with age in the rodent brain, and none has systematically applied quantitative neuroimaging approaches to measure volume changes in regional brain structures over extended periods in the adult rat. METHODS: We used structural magnetic resonance imaging (MRI) in a longitudinal design to examine 2 cohorts of adult P rats, never exposed to alcohol: Cohort A included 8 rats, 7 of which survived the entire study (578 days) and 4 MRI sessions; Cohort B included 9 rats, all of which survived the study (452 days) and 5 MRI sessions. RESULTS: Growth in whole-brain volume reached maximal levels by about 450 days of age, whereas body weight continued its gain without asymptote. Growth was not uniform across the brain structures measured. Over the initial 12 months of the study, the corpus callosum area expanded 36%, cerebellum 17%, and hippocampus 10%, whereas ventricle size was unchanged. Factors affecting growth rate estimates included litter effects, MR image signal-to-noise ratio, and measurement error. CONCLUSION: Unlike longitudinal human reports of regional volume declines in aging brain tissue, several brain structures in adult rats continued growing, and some growth patterns were litter-dependent. Determining normal regional growth patterns of brain and of the substantial variance exerted by litter differences, even in selectively bred rats, is essential for establishing baselines against which normal and aberrant dynamic changes can be detected in animal models of aging and disease.

Aging↗