A reproducible method for automated extraction of brain volumes from 3D human head MR images

An automated method for extracting brain volumes from three commonly acquired three-dimensional (3D) MR images (proton density, T1 weighted, and T2-weighted) of the human head is described. The procedure is divided into four levels: preprocessing, segmentation, scalp removal, and postprocessing. A user-provided reference point is the sole operator-dependent input required, The method's parameters were first optimized and then fixed and applied to 30 repeat data sets from 15 normal older adult subjects to investigate its reproducibility. Percent differences between total brain volumes (TBVs) for the subjects' repeated data sets ranged from .5% to 2.2%. We conclude that the method is both robust and reproducible and has the potential for wide application.

Detection of dimethyl sulfone in the human brain by in vivo proton magnetic resonance spectroscopy

We wish to report the detection of dimethyl sulfone (methylsulfonylmethane, C2H6O2S) in the brain of a normal 62-year-old male using in vivo proton magnetic resonance spectroscopy. The presence of this exogenous metabolite resulted from ingestion of a dietary supplement containing dimethyl sulfone. The concentration of this compound in the brain was measured to be 2.4 mmol, with a washout half life of approximately 7.5 days. The in vivo T-1 and T-2 relaxation times of dimethyl sulfone were measured to be 2180 ms and 385 ms, respectively. The concentration of major brain metabolites, namely N-acetylaspartate, total Creatine and Choline, and myo-Inositol were within normal limits. (C) 2000 Elsevier Science Inc. All rights reserved.

Gender and age-at-first-admission for schizophrenia: Data from Australia and Brazil

In order to examine whether different populations show the same pattern of onset in the Southern Hemisphere, we examined the age-at-first-admission distribution for schizophrenia based on mental health registers from Australia and Brazil. Data on age-at-first-admission for individuals with schizophrenia were extracted from two names-linked registers, (1) the Queensland Mental Health Statistics System, Australia (N=7651, F= 3293, M=4358), and (2) a psychiatric hospital register in Pelotas, Brazil (N=4428, F=2220, M=2208). Age distributions were derived for males and females for both datasets. The general population structure tbr both countries was also obtained. There were significantly more males in the Queensland dataset (gz = 56.9, df3, p < 0.0001 ). Both dataset distributions were skewed to the right. Onset rose steeply after puberty to reach a modal age group of 20-29 for men and women, with a more gradual tail toward the older age groups. In Queensland 68% of women with schizophrenia had their first admissions after age 30, while the proportion from Brazil was 58%. Compared to the Australian dataset, the Brazilian dataset had a slightly greater proportion of first admissions under the age 30 and a slightly smaller proportion over the age of 60 years. This reflects the underlying age distributions of the two populations. This study confirms the wide age range and gender differences in age-at-first-admission distributions for schizophrenia and identified a significant difference in the gender ratio between the two datasets. Given widely differing health services, cultural practices, ethic variability, and the different underlying population distributions, the age-at-first-admission in Queensland and Brazil showed more similarities than differences. Acknowledgments: The Stanley Foundation supported this project.

The effect of mammographic screening on invasive breast cancer in Western Australia

Objective: To determine whether mammographic screening has affected the presentation of invasive breast cancer in Western Australia. Design: Population-based reviews of the presentation of all invasive breast cancers diagnosed in Western Australia in 1989 and 1994. Setting: Western Australia (population 1.8 million), Active recruitment of women aged 50-69 years for mammographic screening began in 1989. Main outcome measures: Size and stage of invasive breast cancers at diagnosis. Results: From 1989 to 1994, the age-standardised incidence rose from 109 to 123 per 100 000 woman-years, based on 584 and 750 cases, respectively. The proportion of all invasive breast cancers detected as a result of a mammogram increased from 9.2% in 1989 to 34.5% in 1994. Among the cases where relevant information was recorded, the proportion of impalpable tumours increased from 7.7% in 1989 to 27.6% in 1994, and the average size of palpable tumours fell. There was an unexpected increase in the proportion of tumours that were negative on assays for oestrogen and progesterone receptors. Conclusions: A relatively simple and inexpensive clinical review has boosted confidence that the outlay of public monies required to establish and conduct screening in Australia appears likely to yield the reductions in mortality from breast cancer that would be predicted on the basis of the earlier controlled trials of mammography.

An unbridgeable gap? Comparing the HIV/AIDS epidemics in Australia and sub-Saharan Africa

OBJECTIVE: To compare the HIV/AIDS epidemics in Australia and sub-Saharan Africa, to outline reasons for differences, and to consider implications for the Asia and Pacific region. METHODS: Comparison of key indicators of the epidemic in Australia, and Africa viewed largely through the experience of the Hlabisa health district, South Africa. RESULTS: To the end of 1997, for all Australia, the estimated cumulative number of HIV infections was approximately 19,000, whereas in Hlabisa 31,000 infections are estimated to have occurred. Compared with the low and declining incidence of HIV in Australia (<1%), estimated incidence in Hlabisa rose to 10% in 1997. In all, 94% of Australian infections have been amongst men; in Hlabisa equal numbers of males and females are infected. Consequently, whereas 3000 children were perinatally exposed to HIV in Hlabisa in 1998 alone, 160 Australian children have been exposed this way. In Australia, HIV-related disease is characterised by opportunistic infection whereas in Hlabisa tuberculosis and wasting dominate. Surveys among gay men in Sydney and Melbourne indicate >80% of HIV infected people receive antiretroviral therapy whereas in Hlabisa these drugs are not available. IMPLICATIONS: It seems possible that Asia and the Pacific will experience a similar HIV/AIDS epidemic to that in Africa. Levels of HIV are already high in parts of Asia, and social conditions in parts of the region might be considered ripe for the spread of HIV. As Australia strengthens economic and political ties within the region, so should more be done to help Pacific and Asian neighbours to prevent and respond to the HIV epidemic.

Loss of connectivity in Alzheimer's disease: an evaluation of white matter tract integrity with colour coded MR diffusion tensor imaging

A novel MRI method-diffusion tensor imaging-was used to compare the integrity of several white matter fibre tracts in patients with probable Alzheimer's disease. Relative to normal controls, patients with probable Alzheimer's disease showed a highly significant reduction in the integrity of the association white matter fibre tracts, such as the splenium of the corpus callosum, superior longitudinal fasciculus, and cingulum. By contrast, pyramidal tract integrity seemed unchanged. This novel finding is consistent with the clinical presentation of probable Alzheimer's disease, in which global cognitive decline is a more prominent feature than motor disturbance.

Screening for abdominal aortic aneurysm: lessons from a population-based study

Objectives: To test the acceptability of screening and to identify modifiable risk factors for abdominal aortic aneurysm (AAA) in men. Design: A trial of ultrasound screening for AAA in a population-based random sample of men aged 65-83 years, and a cross-sectional case-control comparison of men in the same sample. Participants: 12203 men who had an ultrasound examination of their abdominal aorta, and completed a questionnaire covering demographic, behavioural and medical factors. Main outcome measures: Prevalence of AAA, and independent associations of AAA with demographic, medical and lifestyle factors. Results: Invitations to screening produced a corrected response of 70.5%. The prevalence of AAAs (> 30 mm) rose from 4.8% in men aged 65-69 years to 10.8% in those aged 80-83 years. The overall prevalence of large (> 50 mm) aneurysms was 0.69%. In a multivariate logistic model Mediterranean-born men had a 40% lower risk of AAA (> 30 mm) compared with men born in Australia (odds ratio [OR], 0.6; 95% CI, 0.4-0.8), while ex-smokers had a significantly increased risk of AAA (OR, 2.3; 95% CI, 1.9-2.8), and current smokers had even higher risks. AAA was significantly associated with established coronary and peripheral arterial disease and a waist:hip ratio greater than 0.9; men who regularly undertook vigorous exercise had a lower risk (OR, 0.8; 95% CI, 0.7-1.0). Conclusion: Ultrasound screening for AAA is acceptable to men in the likely target population. AAA shares some but not all of the risk factors for occlusive vascular disease, but the scope for primary prevention of AAA in later life is limited.

Diffusion- and perfusion-weighted MRI response to thrombolysis in stroke

Diffusion- and perfusion-weighted magnetic resonance imaging provides important pathophysiological information in acute bra-in ischemia. We performed a prospective study in 19 sub-6-hour stroke patients using serial diffusion- and perfusion-weighted imaging before intravenous thrombolysis, with repeat studies, both subacutely and at outcome. For comparison of ischemic lesion evolution and clinical outcome, we used a historical control group of 21 sub-6-hour ischemic stroke patients studied serially with diffusion- and perfusion-weighted imaging. The two groups were well matched for the baseline National Institutes of Health Stroke Scale and magnetic resonance parameters. Perfusion-weighted imaging-diffusion-weighted imaging mismatch was present in 16 of 19 patients treated with tissue plasminogen activator, and 16 of 21 controls. Perfusion-weighted imaging-diffusion-weighted imaging mismatch patients treated with tissue plaminogen activator had higher recanalization rates and enhanced reperfusion at day 3 (81% vs 47% in controls), and a greater proportion of severely hypoperfused acute mismatch tissue not progressing to infarction (82% vs -25% in controls). Despite similar baseline diffusion-weighted imaging lesions, infarct expansion was less in the recombinant tissue plaminogen activator group (14cm(3) vs 56cm(3) in controls). The positive effect of thrombolysis on lesion growth in mismatch patients translated into a greater improvement in baseline to outcome National Institutes of Health Stroke Scale in the group treated with recombinant tissue plaminogen activator, and a significantly larger proportion of patients treated with recombinant tissue plaminogen activator having a clinically meaningful improvement in National Institutes of Health Stroke Scale of;2:7 points. The natural evolution of acute perfusion-weighted imaging-diffusion-weighted imaging mismatch tissue may be altered by thrombolysis, with improved stroke outcome. This has implications for the use of diffusion- and perfusion-weighted imaging in selecting and monitoring patients for thrombolytic therapy.

Increased rates of ENT surgery among young children: Have clinical guidelines made a difference?

Objectives: To examine the association between introduction of paediatric ear, nose and throat (ENT) surgery guidelines and population procedure rates. To determine changes in children's risk of undergoing ENT surgery. Methods: Trend analysis of incidence of myringotomy, tonsillectomy and adenoidectomy among New South Wales (NSW) children aged 0-14 between 1981 and mid 1999. Poisson regression models were used to estimate annual rates of change pre and postguidelines introduction and age/gender specific rates, and lifetable methods to determine risk of undergoing an ENT procedure by age 15. Results: ENT surgery rates increased by 21% over the study period. Children's risk of surgery increased from 17.9% in 1981 to 20.2% in 1998/99. Guideline introduction was associated with moderate short-term decreases in rates. For tonsillectomy, rates decreased between 1981 and 1983, but then rose continually until the introduction of myringotomy guidelines in 1993, when they fell, only to recommence rising until the end of the study period. For myringotomy, rates rose annually from 1981 to 1992/93 and fell in the 3 years following guideline introduction, after which they rose again. Increases were almost exclusively restricted to children aged 0-4 and correspond with increased use of formal childcare. The prevalence of myringotomy by the age of 5 years rose from 5.6% of children born in 1988/89 to 6.4% of those born in 1994/95, and the prevalence of tonsillectomy from 2.4% to 2.7%. Conclusions: The risk of young Australian children undergoing ENT surgery increased significantly over the last two decades despite the introduction of guidelines and no evidence of an increase in otitis media, one condition prompting surgery. Surgery increased most among the very young. We hypothesize this is related to increasing use of childcare.