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Objective: Assess Aβ deposition longitudinally and explore its relationship with cognition and disease progression.Methods: Clinical follow-up was obtained 20 ± 3 months after [¹¹C]Pittsburgh compound B (PiB)-positron emission tomography in 206 subjects: 35 with dementia of the Alzheimer type (DAT), 65 with mild cognitive impairment (MCI), and 106 age-matched healthy controls (HCs). A second PiB scan was obtained at follow-up in 185 subjects and a third scan after 3 years in 57.Results: At baseline, 97% of DAT, 69% of MCI, and 31% of HC subjects showed high PiB retention. At 20-month follow-up, small but significant increases in PiB standardized uptake value ratios were observed in the DAT and MCI groups, and in HCs with high PiB retention at baseline (5.7%, 2.1%, and 1.5%, respectively). Increases were associated with the number of apolipoprotein E ε4 alleles. There was a weak correlation between PiB increases and decline in cognition when all groups were combined. Progression to DAT occurred in 67% of MCI with high PiB versus 5% of those with low PiB, but 20% of the low PiB MCI subjects progressed to other dementias. Of the high PiB HCs, 16% developed MCI or DAT by 20 months and 25% by 3 years. One low PiB HC developed MCI.Interpretation: Aβ deposition increases slowly from cognitive normality to moderate severity DAT. Extensive Aβ deposition precedes cognitive impairment, and is associated with ApoE genotype and a higher risk of cognitive decline in HCs and progression from MCI to DAT over 1 to 2 years. However, cognitive decline is only weakly related to change in Aβ burden, suggesting that downstream factors have a more direct effect on symptom progression. [ABSTRACT FROM AUTHOR]

Objective: Elucidating the role of aggregated beta-amyloid in relation to gray matter atrophy is crucial to the understanding of the pathological mechanisms of Alzheimer disease and for the development of therapeutic trials. The present study aims to assess this relationship.Methods: Brain magnetic resonance imaging and [(11)C]Pittsburgh compound B (PiB)-positron emission tomography scans were obtained from 94 healthy elderly subjects (49 with subjective cognitive impairment), 34 patients with mild cognitive impairment, and 35 patients with Alzheimer disease. The correlations between global and regional neocortical PiB retention and atrophy were analyzed in each clinical group.Results: Global and regional atrophy were strongly related to beta-amyloid load in participants with subjective cognitive impairment but not in patients with mild cognitive impairment or Alzheimer disease. Global neocortical beta-amyloid deposition correlated to atrophy in a large brain network including the hippocampus, medial frontal and parietal areas, and lateral temporoparietal cortex, whereas regional beta-amyloid load was related to local atrophy in the areas of highest beta-amyloid load only, that is, medial orbitofrontal and anterior and posterior cingulate/precuneus areas.Interpretation: There is a strong relationship between beta-amyloid deposition and atrophy very early in the disease process. As the disease progresses to mild cognitive impairment and Alzheimer disease clinical stages, pathological events other than, and probably downstream from, aggregated beta-amyloid deposition might be responsible for the ongoing atrophic process. These findings suggest that antiamyloid therapy should be administered very early in the disease evolution to minimize synaptic and neuronal loss. [ABSTRACT FROM AUTHOR]

We characterized atherosclerotic plaque components with a novel cryo-imaging system in lieu of standard histological methods commonly used for imaging validation and research endpoints. We aim to accurately identify plaque tissue types from fresh cadaver specimens rapidly (less than 5 h) in three dimensions for large specimens (up to 4 cm vessel segments). A single-blind validation study was designed to determine sensitivity, specificity and inter-rater agreement (Fleiss' Kappa) of cryo-imaging tissue types with histology as the gold standard. Six naïve human raters identified 344 tissue type samples in 36 cryo-image sets after being trained. Tissue type sensitivities are as follows: greater than 90% for adventitia, media-related, smooth muscle cell ingrowth, external elastic lamina, internal elastic lamina, fibrosis, dense calcification and haemorrhage; greater than 80% for lipid and light calcification; and greater than 50% for cholesterol clefts. Specificities were greater than 95% for all tissue types. The results demonstrate convincingly that cryo-imaging can be used to accurately identify most tissue types. If the cryo-imaging data are entered into visualization software, three-dimensional renderings of the plaque can be generated to visualize and quantify plaque components. [ABSTRACT FROM AUTHOR]

There is increasing evidence that educating trainee surgeons by simulation is preferable to traditional operating-room training methods with actual patients. Apart from reducing costs and risks to patients, training by simulation can provide some unique benefits, such as greater control over the training procedure and more easily defined metrics for assessing proficiency. Virtual reality (VR) simulators are now playing an increasing role in surgical training. However, currently available VR simulators lack the fidelity to teach trainees past the novice-to-intermediate skills level. Recent technological developments in other industries using simulation, such as the games and entertainment and aviation industries, suggest that the next generation of VR simulators should be suitable for training, maintenance and certification of advanced surgical skills. To be effective as an advanced surgical training and assessment tool, VR simulation needs to provide adequate and relevant levels of physical realism, case complexity and performance assessment. Proper validation of VR simulators and an increased appreciation of their value by the medical profession are crucial for them to be accepted into surgical training curricula. [ABSTRACT FROM AUTHOR]

Dose planning for prostate radiation therapy is performed using computed tomography (CT) scans that provide the electron density information needed for individual patients' radiation dose calculations. For visualising the prostate and determining the target volume for radiation treatment, magnetic resonance imaging (MRI) gives vastly superior soft-tissue contrast. However, currently, MRI scans cannot be used for dose planning, as they do not provide the electron density information. We aimed to develop an alternative and efficient MRI-only image-based workflow, enabling both organ delineation and dose planning to be performed using MRI, with "pseudo-CT scans" generated from MRI scans supplying the information for dose planning. The feasibility of implementing MRI-based prostate radiation therapy planning is being investigated through collaboration between the clinical and medical physics group at the Calvary Mater Newcastle Hospital/University of Newcastle and the biomedical imaging processing group at the CSIRO (Commonwealth Scientific and Industrial Research Organisation) Australian e-Health Research Centre. Results comparing Hounsfield units calculated from CT scans and from MRI-based pseudo-CT scans for 39 patients showed very similar average values for the prostate, bladder, bones and rectum, confirming that pseudo-CT scans can replace CT scans for accurate radiation dose calculations. MRI-based radiotherapy planning can also be used for tumours in other locations, such as head and neck, and breast cancers. [ABSTRACT FROM AUTHOR]

Longer life expectancies lead to increases in the prevalence of age-associated illnesses. The number of Australians with dementia is predicted to rise, from 234,000 in 2009 to over 1 million by 2050, as a result of the increased prevalence of Alzheimer's disease (AD), the leading cause of dementia in the elderly. Early diagnosis of AD will become more important as disease-modifying therapies emerge within the next decade. Advances in molecular neuroimaging with amyloid-β-specific radioligands for positron emission tomography, aided by magnetic resonance imaging techniques, allow detection of AD years before symptoms of dementia develop. Longitudinal prospective studies, such as the Australian Imaging Biomarkers and Lifestyle (AIBL) study of ageing, will determine the sensitivity and specificity of these analysis techniques for diagnosing AD and predicting cognitive decline. [ABSTRACT FROM AUTHOR]