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PubMed2003

Frontal and occipital horn width ratio for the evaluation of small and asymmetrical ventricles.

The aim of this study was the introduction of a new linear ventricular measurement which has a better correlation with ventricular volume than the commonly used linear measurements, especially in chronically shunted patients with small and/or asymmetrical ventricles. Ventricular volume, brain volume, Evans ratio, Schierman index, cella media index and frontal and occipital horn ratio were measured from CT scans of 57 shunted hydrocephalic patients and 20 normal control children. Four groups of patients were identified with regards to the ventricular size and symmetry (small, large, symmetrical and asymmetrical). A new linear measurement was defined as half of the ratio of the frontal and occipital ventricular width to that of the skull (frontal and occipital horn width ratio; FOHWR) and compared to other linear measurements in different patient groups. FOHWR showed better correlation with ventricular size and ventricular brain ratio than the ventricular linear measurements currently in use, especially in chronically shunted patients with small and/or asymmetrical ventricles.

Adolescent↗
PubMed1994

Regulation of mammalian brain cell volume.

Maintenance of brain cell volume is of crucial importance for normal central nervous system (CNS) function. This review considers volume regulation primarily in response to disturbances of body fluid osmolality. Brain cells counter the tendency to swell or shrink by appropriate adjustment of their internal osmotic potential. This is achieved by loss or uptake of inorganic ions and low molecular weight organic solutes (osmolytes). The latter comprise mainly amino acids, myoinositol, choline, and methylamines. Taurine may be of particular importance in volume control, especially in young animals. Brain cell volume regulation, however, is only one contributory factor to maintenance of constant brain volume (water content), and operates in parallel with important alterations in bulk fluid and electrolyte movement across the blood-brain barrier and between the interstitium and cerebrospinal fluid, which themselves moderate the requirement for transient alteration in cell volume during acute osmotic imbalance. Although altered cerebral content of inorganic ions and osmolytes are usually regarded as responses, respectively, to acute and chronic osmotic disturbances, osmolytes (especially taurine) may also participate in short-term cell volume regulation.

Animals↗
PubMed1995

The effect of white matter hyperintensity volume on brain structure, cognitive performance, and cerebral metabolism of glucose in 51 healthy adults.

OBJECTIVE: To assess the association of MRI white matter hyperintensities (WMHI) with cognitive performance, cerebral structure, and cerebral metabolism in 51 healthy individuals aged 19 to 91 years without cerebrovascular risk factors. BACKGROUND: Abnormal white matter signals have been associated with brain atrophy, reduced cerebral blood flow, focal neurologic signs, gait disorder, and poorer neuropsychological test performance. Most studies of WMHI, however, include subjects with hypertension or other identifiable causes of cerebrovascular disease that may have an independent effect on brain structure and function. To assess brain changes associated with WMHI independent of cerebrovascular risk factors, we determined WMHI volume, brain volume, cerebral metabolism, and cognitive performance for a group of subjects free of medical illness. Regional cerebral metabolism and cognitive domains were also assessed to evaluate the possible role of frontal lobe dysfunction in subjects with WMHI. DESIGN: Cross-sectional study of 51 very healthy subjects aged 19 to 91 years. METHODS: WMHI, brain, and CSF volumes were determined by MRI segmentation. Neuropsychological tests were employed to assess multiple cognitive domains. Brain metabolism was determined from 18-fluoro-2-deoxy-D-glucose PET. Multivariate relations were tested with stepwise linear regression. Models included the potential confounders of age and education where appropriate. RESULTS: The distribution of WMHI volume was bimodal, with five subjects having WMHI volumes beyond three SDs from the normally distributed population. A WMHI volume of greater than 0.5% of intracranial volume was considered abnormal. Within the multivariate models, WMHI volumes were significantly predictive of increased ventricular volume, reduced brain volume, and reduced cognitive scores. Subjects with greater than 0.5% WMHI volume also had significantly lower frontal lobe metabolism, significantly higher systolic blood pressure, significantly larger ventricular volume, and significantly lower scores on frontal lobe-mediated neuropsychological tests than age-matched controls. CONCLUSION: WMHI volume is associated with structural and functional brain changes even within a group of very healthy individuals. WMHI is associated with poorer frontal lobe cognitive function and, when severe, is accompanied by significantly reduced frontal lobe metabolism. Subjects with large WMHI volumes have significantly higher systolic blood pressure, brain atrophy, reduced cerebral metabolism, and lower scores on tests of frontal lobe function than age-matched controls. Large amounts of WMHI are, therefore, pathologic and may be related to elevated systolic blood pressure even when it is within the normal age-related range.

Adult↗
PubMed2001

Intra-observer, inter-observer and inter-scanner variations in brain MRI volume measurements in multiple sclerosis.

INTRODUCTION: Measurement of brain volume on magnetic resonance imaging (MRI) scans is regarded as an objective marker of multiple sclerosis (MS) severity with the potential to monitor treatment efficacy accurately. This study was performed to assess the variability of brain MRI volume measurements. PATIENTS AND METHODS: We studied nine patients with relapsing-remitting MS, who were imaged on two occasions (separated by an interval of 24 h) using two different MR scanners and fast fluid-attenuated inversion recovery (fast-FLAIR) sequences. The whole brain volume computed from each image was measured three times by three observers using a seed-growing technique based on signal intensity thresholding. Intra-observer, inter-observer and inter-scanner variabilities were expressed as coefficients of variations (COVs). The inter-scanner variability included not only the intra-observer variation but also the repositioning variability and the variation in observed brain volume caused by different scanner hardware and sequence implementations. RESULTS: There was no statistically significant difference in patients' brain volume values between observers (P=0.82) or between scanners (P=0.30). The mean intra-observer COV was 1.2% (s.e.=0.4%), the mean inter-observer COV was 1.8% (s.e.=0.8%) and the mean inter-scanner COV was 2.4% (s.e.=1.2%). The intra-observer variance was not statistically different from those found between observers (P=0.83) or scanners (P=0.44). CONCLUSION: The intra-observer variability in brain volume measurements found in this study was within the range of intra-observer variability found in previous studies. This study shows that the use of different observers and MR scanners has only a small influence on the measured brain volume and does not affect the reproducibility of this measurement greatly.

Adult↗
PubMed1985

Brain vascular volume, electrolytes and blood-brain interface in the cuttlefish Sepia officinalis (Cephalopoda).

Cephalopod molluscs have complex brains and behaviour, yet little is known about the permeability of their blood-brain interface. This paper presents studies on the brain fluid and electrolyte compartments of the cuttlefish Sepia, as a preliminary to characterization of the permeability of the blood-brain interface in this group. Sepia is shown to be a satisfactory experimental animal, and techniques are described for anaesthesia, cannulation, and tissue and fluid analysis. Our ionic analyses of body fluids are in general agreement with those of earlier workers. Analysis of brain tissue suggests that the extracellular space is 17-20 ml 100 g tissue-1 (i.e. 17-20%). Two large molecular weight tracers, 125I-human serum albumin (HSA) and Blue dextran, give consistent values for the brain vascular volume of 3.5-5.5%, slightly higher than in vertebrates. The HSA results further confirm that the Sepia blood-brain interface is relatively tight to proteins. Finally, we have shown that the fluid surrounding the brain, pericerebral fluid (PCF), is in relatively free communication with plasma.

Animals↗
PubMed2006

Plexin B3 is genetically associated with verbal performance and white matter volume in human brain.

The presence of genetic influences on cognitive performance and brain volume is well established. However, specific genetic determinants of the variance of these quantitative traits are not yet known. Plexins act as receptors for semaphorins and are implicated in axon guidance, which is a key process in brain development. We have previously shown that plexin B3 is a highly potent stimulator of neurite outgrowth, which makes its gene PLXNB3 an intriguing candidate gene for traits related to human brain development and cerebral connectivity. We identified several polymorphisms in PLXNB3 predicting changes of amino acids (V598I, E1156D and V1596E) conserved at the corresponding positions of the orthologs in mouse and chimpanzee. PLXNB3 was genotyped in 303 healthy volunteers and 42 male patients with schizophrenia. Cognitive performance was measured with the vocabulary test (Wortschatztest (WST)), a method to estimate roughly general intelligence (g). Brain morphology was characterized by magnetic resonance imaging. Compared to subjects not carrying the modern, human-specific haplotype A, carriers of A scored higher in vocabulary test (WST) irrespective of diagnosis (P=0.0004). This effect could be observed in three independent groups (healthy males: P=0.048; schizophrenic males: P=0.034 and healthy females: P=0.037). Additionally, the haplotype A was associated with increased volume of brain white matter that in turn correlated with performance in the vocabulary test. These findings suggest that plexin B3 may influence cognitive performance, and the development of white matter in vivo in a way similar to its known stimulating effect on neurite outgrowth in vitro. These novel observations warrant further replication in independent samples.

Adult↗
PubMed2000

Sensitivity and reproducibility of volume change measurements of different brain portions on magnetic resonance imaging in patients with multiple sclerosis.

The course of multiple sclerosis (MS) can be monitored by measuring changes in brain volume, but consensus is still lacking on the best strategy to be adopted. We compared the reproducibility and sensitivity of volume measurements from different brain portions for detecting changes on magnetic resonance imaging (MRI) in patients with MS. T1-weighted MRI of the brain was performed in 50 patients with relapsing-remitting MS at study entry and after an average follow-up of 18.4 months. Using a semiautomated technique for brain parenchyma segmentation, the volumes of the following brain portions were measured: (a) the whole brain (whole-brain volume, WBV), (b) the seven slices rostral to the velum interpositum (seven-slice volume, SSV), (c) the central slice of the image set (central-slice volume, CSV) and (d) the infratentorial regions (infratentorial-brain volume, IBV). All these measurements were carried out by a single observer and were repeated twice on ten randomly selected scans to test the intra-observer reproducibility using the four strategies. At follow-up there was a significant decrease in all the measures of brain volume (P ranged from 0.002 to < 0.001). The univariate correlations between changes in WBV, SSV, CSV and IBV were all statistically significant, with the exception of that between changes in CSV and IBV; r values ranged from 0.34 (for the WBV/IBV correlation) to 0.80 (for the WBV/SSV correlation). The mean intra-observer coefficient of variations were 1.9% for WBV, 1.5% for SSV, 2.9% for CSV and 2.2% for IBV measurements. The measurement of volume on a portion of brain selectively including the regions in which MS pathology is more diffuse is as reliable and sensitive to disease-related changes as that on the whole brain, with significant time saving for processing.

Adult↗
PubMed2002

Regulation of brain water during acute hyperosmolality in ovine fetuses, lambs, and adults.

In adult rats, when plasma osmolality increases, water flows across the blood-brain barrier down its concentration gradient from brain to plasma, and brain volume deceases. The brain responds to this stress by gaining osmotically active solutes, which limit water loss. This phenomenon is termed brain volume (water) regulation. We tested the hypothesis that brain volume regulation is more effective in young lambs and adult sheep than in fetuses, premature lambs, and newborn lambs. Brain water responses to acute hyperosmolality were measured in the cerebral cortex, cerebellum, and medulla of fetuses at 60 and 90% of gestation, premature ventilated lambs at 90% of gestation, newborn lambs, young lambs at 20-30 days of age, and adult sheep. After exposure of the sheep to increases in systemic osmolality with mannitol plus NaCl, brain water content and electrolytes were quantified. The ideal osmometer is a system in which impermeable solutes do not enter or leave in response to an osmotic stress. There were significant differences from an ideal osmometer in the cerebral cortex of fetuses at 90% of gestation, cerebral cortex, and cerebellum of newborn lambs, and cerebral cortex, cerebellum, and medulla of young lambs and adult sheep; however, there were no differences in the brain regions of fetuses at 60% of gestation and premature lambs, cerebellum and medulla of fetuses at 90% of gestation, and medulla of newborn lambs. We conclude that 1) brain water loss is maximal and brain volume regulation impaired in most brain regions of fetuses at 60 and 90% of gestation and premature lambs; 2) brain volume regulation develops first in the cerebral cortex of the fetuses at 90% of gestation and in the cerebral cortex and cerebellum of newborn lambs, and then it develops in the medulla of the lambs at 20-30 days of age; 3) brain water loss is limited and volume regulation present in the brain regions of young lambs and adult sheep; and 4) the ability of the brain to exhibit volume regulation develops in a region- and age-related fashion.

Aging↗
PubMed2003

Retrograde amnesia and the volume of critical brain structures.

There are many controversies concerning the structural basis of retrograde amnesia (RA). One view is that memories are held briefly within a medial temporal store ("hippocampal complex") before being "consolidated" or reorganised within temporal neocortex and/or networks more widely distributed within the cerebral cortex. An alternative view is that the medial temporal lobes are always involved in the storage and retrieval (reactivation) of autobiographical memories (multiple trace theory). The present study used quantitative magnetic resonance imaging (MRI) in 40 patients with focal pathology/volume loss in different sites, to examine the correlates of impairment on three different measures of RA. The findings supported the view that widespread neural networks are involved in the storage and retrieval of autobiographical and other remote memories. Brain volume measures in critical structures could account for 60% of variance on autobiographical memory measures (for incidents and facts) in diencephalic patients and for 60-68% of variance in patients with frontal lesions. Significant correlations with medial temporal lobe volume were found only in the diencephalic group, in whom they were thought to reflect thalamic changes, but not in patients with herpes encephalitis or hypoxia in whom the temporal lobes were particularly implicated. The latter finding fails to support one of the main predictions of multiple trace theory, as presently expounded.

Amnesia, Retrograde↗
PubMed1994

Effect of steroids on iopamidol blood-brain transfer constant and plasma volume in brain tumors measured with X-ray computed tomography.

Tumor blood-brain transfer constant of iopamidol (K) and plasma volume (Vp) were measured in 10 patients with primary brain tumors before and after 7 days of dexamethasone treatment (4 x 4 mg per oral per day) using X-ray computed tomography. Both K and Vp decreased significantly after dexamethasone treatment with p < 0.01 and 0.09 respectively according to one-tail paired t-test. The mean percentage decrease in K and Vp was 32% and 10% respectively. Functional images of the two parameters before and after treatment were generated and showed clearly the effect of steroids on the reduction of K in brain tumors. In contrast, when before and after treatment contrast enhanced CT scans were compared, no difference was observed in the enhancement in 8 out of 10 cases. The result obtained support the conclusion that: (1) corticosteroids reduce the blood-brain permeability to small hydrophilic molecules; (2) the X-ray computed tomography method we have developed can be used to measure the K and Vp response of brain tumors to steroid therapy; and, (3) ordinary contrast enhanced CT scans at one fixed time or multiple times after contrast injection are not sensitive in detecting the reduction of K due to steroids.

Blood-Brain Barrier↗
PubMed2006

Diffuse structural and metabolic brain changes in Fabry disease.

OBJECTIVES: To assess structural and metabolic brain changes in subjects affected by Fabry disease (FD) or carrying the disease mutation. BACKGROUND: FD is an X-linked metabolic disorder due to alpha-galactosidase A deficiency, which leads to storage of glycosphingolipids in many tissues and organs. Previous MR studies have shown structural and metabolic brain abnormalities in FD patients. It is not clear, however, whether tissue damage can be seen in both the brains of hemizygous and heterozygous and whether quantitative MR metrics are useful to monitor disease evolution. DESIGN/METHODS: We studied 4 males and 4 females with FD. Each subject underwent brain proton MRI/MR spectroscopic imaging (MRSI) examinations to obtain measures of total brain volumes, total brain lesion volumes, magnetization transfer ratios (MTr) in WM and central brain levels of N-acetylaspartate (NAA) to creatine (Cr). A second MR examination was performed in five subjects after 2 years. RESULTS: Focal WM lesions were found in 2 males and 1 female. The MTr values were always low in the WM lesions of FD subjects (p < 0.001) and also were low in the normal-appearing WM of 2 affected males. Total brain volumes were never decreased in FD subjects. Brain NAA/Cr values were significantly (p = 0.005) lower in FD subjects than in normal controls and correlated closely with Rankin scale measures (r = -0.79). On follow-up examinations, no significant MR changes were found. However, the small changes in NAA/Cr correlated closely with changes in Rankin scores (r = -0.86). CONCLUSIONS: Subtle structural and metabolic tissue damage can extend beyond WM lesions in FD subjects. Diffuse brain NAA/Cr decrease can be found in FD subjects in relation to the degree of their CNS involvement and its evolution over time.

Adult↗
PubMed2004

Connection between p53 gene Bam HI RFLP polymorphism with the volume of brain infarction in patients with carotid atherothrombotic ischemic stroke.

PURPOSE: The aim of our investigation was to study the connection between p53 gene Bam HI RFLP polymorphism and the brain infarction volume in patients with atherothrombotic ischemic stroke that could highlight certain genetic aspects of the individual sensibility of brain tissue to acute ischemia. MATERIALS AND METHODS: Diallelic Bam HI RFLP polymorphism in 5' flanking region p53 gene was studied in 96 patients with carotid atherothrombotic stroke from Moscow population. Magnetic resonance imaging was conducted on day 7 after the stroke onset. The manual morphometry and "Osiris" morphometric hardware (by the Hospital of the University of Geneva) were used for assessment of the infarction volume. RESULTS: The predominance of small-size infarctions (< 40 cm3) was revealed in patients with (-/-) Bam HI RFLP p53 genotype versus patients with (-/+) (X2 = 19.7; P < 0.001) and (+/+) (X2 = 12.288; P < 0.001) genotypes. According to the Bayesian's statistics, in patients with (-/-) p53 Bam HI genotype the development of a small-size infarction in atherothrombotic ischemic stroke can be prognosticated with probability more than 65%. CONCLUSIONS: A significant association between p53 gene Bam HI RFLP polymorphism and the infarction volume was found in patients with carotid atherothrombotic stroke from Moscow population. These results additionally confirm that apoptosis plays an important role in the formation of ischemic brain lesion and that drugs with anti-apoptotic properties may prove beneficial in stroke patients.

Acute Disease↗
PubMed2005

MR quantitation of volume and diffusion changes in the developing brain.

BACKGROUND AND PURPOSE: Brain volume and diffusion change during maturation. Quantitation of these changes may be helpful in understanding normal brain development. We used diffusion-weighted imaging to characterize the volumetric and diffusion changes in vivo. METHODS: We recruited 30 pediatric volunteers (aged 1 month-17 years; 14 male, 16 female). Diffusion was measured in three orthogonal directions with a b value of 1000 s/mm2. The diffusion parameters from the entire brain were calculated and fitted to a triple gaussian model. In addition, region-of-interest measurements were made in caudate, thalamus, genu and splenium of the corpus callosum, and periventricular white matter (PVWM). The brain volume was measured by counting pixels and by using the model. RESULTS: Water diffusion of the whole brain, caudate, thalamus, genu and splenium of the corpus callosum, and PVWM decreased during maturation, with the most significant change within the first 2 years. Robust negative correlations were found between age and the measured average diffusion constant (Dav) values in each of the measured locations (P <.005). Volumes of different cerebral compartments and the total intracranial volume (ICV) increased rapidly during the first 2 years of life and then had a slower growth process through adolescence. Age was correlated with the ICV and the volume of each brain compartment (P <.005). CONCLUSION: Brain diffusion decreases and brain volume increases during maturation, with the most significant changes occurring within the first 2 years of life. The brain model used in this study provides a good estimate of the increasing brain volume.

Adolescent↗
PubMed2005

Late-onset dementia: structural brain damage and total cerebral blood flow.

PURPOSE: To prospectively compare indicators of structural brain damage and total cerebral blood flow in patients with late-onset dementia, subjects of the same age with optimal cognitive function, and young subjects. MATERIALS AND METHODS: The institutional ethics committee approved the studies, and all participants (or their guardians) gave informed consent. The test group included 17 patients older than 75 years (four men, 13 women; median age, 83 years) and with a diagnosis of dementia according to the criteria of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition. The control group included 16 subjects (four men, 12 women; median age, 87 years) with optimal cognitive function, who were selected from among 599 elderly subjects enrolled in a population-based follow-up study, and 15 young healthy subjects (seven men, eight women; median age, 29 years). Measurements of intracranial and total brain volumes, structural brain damage, and cerebral blood flow were obtained with magnetic resonance imaging. Mean values were compared with the t test; medians, with the Mann-Whitney U test. RESULTS: Values for total brain volume were significantly smaller in elderly subjects (P < .001) but did not differ significantly between patients with dementia and subjects of the same age with optimal cognitive function (P = .69). Among the elderly, significantly higher scores for number and extent of white matter areas of signal hyperintensity (P = .028) and lower magnetization transfer ratios (P = .016) indicated greater structural brain damage in those with dementia. Cerebral blood flow was 246 mL/min lower (P < .001) in elderly subjects than in young subjects. In patients with dementia, cerebral blood flow was 108 mL/min lower than that in subjects of the same age with optimal cognitive function (551 vs 443 mL/min, P < .001). CONCLUSION: The combined observations of more structural brain damage and lower cerebral blood flow in demented elderly individuals than in subjects of the same age with optimal cognitive function support the hypothesis that vascular factors contribute to dementia in old age.

Aged↗
PubMed1992

Cranial computed tomographic observations in multi-infarct dementia. A controlled study.

BACKGROUND AND PURPOSE: We compared cranial computed tomography findings among 58 multi-infarct dementia index cases and 74 multi-infarct control subjects without cognitive impairment to identify potential determinants of multi-infarct dementia. METHODS: The cranial computed tomography records of acute ischemic stroke patients with a history of multiple cerebral infarcts were compared to determine the number, location, and size of cerebral infarcts; the pattern of infarction; brain volume loss; and the degree of white matter lucency, sulcal enlargement, and ventricular enlargement. Multi-infarct patients were divided into two groups: 1) index cases were defined as those with multi-infarct dementia as defined by the Diagnostic and Statistical Manual of Mental Disorders, edition 3 (DSM-III) criteria; and 2) control subjects were defined as those multi-infarct patients without dementia or multi-infarct dementia according to DSM-III criteria. RESULTS: Overall, multi-infarct index cases had more cerebral infarcts, more cortical and subcortical left hemisphere infarcts, higher mean ventricular volume to brain volume ratio, more extensive enlargement of the body of the lateral ventricles and cortical sulci, and a higher prevalence of white matter lucencies. Among multi-infarct cases and control subjects the most frequent site of infarction was the subcortical region, and the most frequent pattern of infarction was lacunar. Stepwise logistic regression analysis examined cranial computed tomography as well as other factors and showed that level of education, stroke severity, left cortical infarction, and diffuse enlargement of the left lateral ventricle were the best overall predictors of multi-infarct dementia. CONCLUSIONS: Level of education, stroke severity, and left hemisphere infarction may be predictors of multi-infarct dementia.

Brain↗
PubMed1999

A comparative volumetric analysis of the prefrontal cortex in human and baboon MRI.

The proportion of prefrontal cortex in humans was compared to the proportion of prefrontal cortex in baboons (Papio anubis). Prefrontal cortex, dorsal prefrontal, orbital prefrontal cortex and total brain volumes were determined from magnetic resonance images of 20 healthy adult human females and 5 adult female baboons. Results showed that the proportion of prefrontal cortex volume relative to total brain volume in humans was significantly larger in humans than in baboons. The percentage of prefrontal cortex relative to total brain volume was 12.51 for humans and 10.68 for baboons. Similarly, the proportion of both dorsal and orbital prefrontal cortex volumes is larger in human brains. Relative to total brain volume, the percentages of dorsal and orbital prefrontal cortex was 8.22% and 4.29% respectively in humans and 7.21% and 3.47% in baboons. A regression analysis showed that the human prefrontal cortex was larger than would be predicted for a baboon of equal total brain volume. These results suggest that increased prefrontal lobe volume could underlie some of the differences between human and hominoid primates. On the other hand, the small magnitude of the difference might underlie similarities between the species and should encourage a search for other structures that are disproportionately larger in humans.

Adult↗
PubMed1987

Brain blood volume, flow, and oxygen utilization measured with 15O radiotracers and positron emission tomography: revised metabolic computations.

We have revised our methods for calculating regional blood volume, flow, oxygen extraction, and oxygen utilization from positron emission tomography data obtained using 15O-labeled radiotracers. These revisions include radioactive decay explicitly within the model equations instead of requiring all measured activity to be corrected for decay prior to incorporation in the equations. The revised equations yield small but significant differences in the computed values.

Blood Volume↗
PubMed2006

Modeling radiation dosimetry to predict cognitive outcomes in pediatric patients with CNS embryonal tumors including medulloblastoma.

PURPOSE: Model the effects of radiation dosimetry on IQ among pediatric patients with central nervous system (CNS) tumors. METHODS AND MATERIALS: Pediatric patients with CNS embryonal tumors (n = 39) were prospectively evaluated with serial cognitive testing, before and after treatment with postoperative, risk-adapted craniospinal irradiation (CSI) and conformal primary-site irradiation, followed by chemotherapy. Differential dose-volume data for 5 brain volumes (total brain, supratentorial brain, infratentorial brain, and left and right temporal lobes) were correlated with IQ after surgery and at follow-up by use of linear regression. RESULTS: When the dose distribution was partitioned into 2 levels, both had a significantly negative effect on longitudinal IQ across all 5 brain volumes. When the dose distribution was partitioned into 3 levels (low, medium, and high), exposure to the supratentorial brain appeared to have the most significant impact. For most models, each Gy of exposure had a similar effect on IQ decline, regardless of dose level. CONCLUSIONS: Our results suggest that radiation dosimetry data from 5 brain volumes can be used to predict decline in longitudinal IQ. Despite measures to reduce radiation dose and treatment volume, the volume that receives the highest dose continues to have the greatest effect, which supports current volume-reduction efforts.

Central Nervous System Neoplasms↗