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  • 11
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    Biopsy validation of 18F-DOPA PET and biodistribution in gliomas for neurosurgical planning and radiotherapy target delineation: results of a prospective pilot study (2013)
    Oxford University Press
    Details
    Publication Date: 2013-07-18
    Description: Background Delineation of glioma extent for surgical or radiotherapy planning is routinely based on MRI. There is increasing awareness that contrast enhancement on T1-weighted images (T1-CE) may not reflect the entire extent of disease. The amino acid tracer 18 F-DOPA (3,4-dihydroxy-6-[18F] fluoro- l -phenylalanine) has a high tumor-to-background signal and high sensitivity for glioma imaging. This study compares 18 F-DOPA PET against conventional MRI for neurosurgical biopsy targeting, resection planning, and radiotherapy target volume delineation. Methods Conventional MR and 18 F-DOPA PET/CT images were acquired in 10 patients with suspected malignant brain tumors. One to 3 biopsy locations per patient were chosen in regions of concordant and discordant 18 F-DOPA uptake and MR contrast enhancement. Histopathology was reviewed on 23 biopsies. 18 F-DOPA PET was quantified using standardized uptake values (SUV) and tumor-to-normal hemispheric tissue (T/N) ratios. Results Pathologic review confirmed glioma in 22 of 23 biopsy specimens. Thirteen of 16 high-grade biopsy specimens were obtained from regions of elevated 18 F-DOPA uptake, while T1-CE was present in only 6 of those 16 samples. Optimal 18 F-DOPA PET thresholds corresponding to high-grade disease based on histopathology were calculated as T/N 〉 2.0. In every patient, 18 F-DOPA uptake regions with T/N 〉 2.0 extended beyond T1-CE up to a maximum of 3.5 cm. SUV was found to correlate with grade and cellularity. Conclusions 18 F-DOPA PET SUV max may more accurately identify regions of higher-grade/higher-density disease in patients with astrocytomas and will have utility in guiding stereotactic biopsy selection. Using SUV-based thresholds to define high-grade portions of disease may be valuable in delineating radiotherapy boost volumes.
    Print ISSN: 1522-8517
    Electronic ISSN: 1523-5866
    Topics: Medicine
    Published by Oxford University Press on behalf of The Society for Neuro-Oncology (SNO).
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  • 12
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    Stretchable liquid-crystal blue-phase gels (2014)
    Springer Nature
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    Publication Date: 2014-07-24
    Description: Nature Materials 13, 817 (2014). doi:10.1038/nmat3993 Authors: F. Castles, S. M. Morris, J. M. C. Hung, M. M. Qasim, A. D. Wright, S. Nosheen, S. S. Choi, B. I. Outram, S. J. Elston, C. Burgess, L. Hill, T. D. Wilkinson & H. J. Coles Liquid-crystalline polymers are materials of considerable scientific interest and technological value. An important subset of these materials exhibit rubber-like elasticity, combining the optical properties of liquid crystals with the mechanical properties of rubber. Moreover, they exhibit behaviour not seen in either type of material independently, and many of their properties depend crucially on the particular mesophase employed. Such stretchable liquid-crystalline polymers have previously been demonstrated in the nematic, chiral-nematic, and smectic mesophases. Here, we report the fabrication of a stretchable gel of blue phase I, which forms a self-assembled, three-dimensional photonic crystal that remains electro-optically switchable under a moderate applied voltage, and whose optical properties can be manipulated by an applied strain. We also find that, unlike its undistorted counterpart, a mechanically deformed blue phase exhibits a Pockels electro-optic effect, which sets out new theoretical challenges and possibilities for low-voltage electro-optic devices.
    Print ISSN: 1476-1122
    Electronic ISSN: 1476-4660
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Natural Sciences in General , Physics
    Published by Springer Nature
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  • 13
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    Tumefactive Cerebral Amyloid Angiopathy Mimicking CNS Neoplasm (2012)
    The American Roentgen Ray Society (ARRS)
    Details
    Publication Date: 2012-12-20
    Description: OBJECTIVE. The tumefactive variant of cerebral amyloid angiopathy (CAA) is rare. In this article we describe imaging findings associated with this entity and evaluate the role of susceptibility MRI sequences in its diagnosis. CONCLUSION. Our findings suggest that in elderly patients, susceptibility sequences should be part of prebiopsy MRI for tumefactive lesions. Identification of characteristic diffuse microhemorrhages should prompt inclusion of CAA in the differential diagnosis, targeted biopsy of the cortex and leptomeninges, and pathologic staining for CAA.
    Print ISSN: 0361-803X
    Electronic ISSN: 1546-3141
    Topics: Medicine
    Published by The American Roentgen Ray Society (ARRS)
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  • 14
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    Multi-decadal water-table manipulation alters peatland hydraulic structure and moisture retention (2014)
    Wiley-Blackwell
    Details
    Publication Date: 2014-12-11
    Description: A peatland complex disturbed by berm construction in the 1950's was used to examine the long-term impact of water table (WT) manipulation on peatland hydraulic properties and moisture retention at three adjacent sites with increasing depth to WT (WET, INTermediate reference, and DRY). Saturated hydraulic conductivity ( K s ) was found to decrease with depth by several orders of magnitude over a depth of 1–1.5 m at all sites. The depth-dependence of WT response to rainfall was similar across sites: WT response increased from 1:1 at the surface, to 5:1 at 50 cm depth. While surface specific yield ( S y ) values were similar across all sites, it decreased with depth at a rate of 0.014 cm -1 in hollows and 0.007 cm -1 in hummocks. Bulk density ( ρ b ) exhibited similar depth-dependent trends as S y , and explains a high amount of variance (r 2  〉 0.69) in moisture retention across a range of pore water pressures (-15 to -500 cm H 2 O). Due to higher ρ b , hollow peat had greater moisture retention, where site effects were minimal. However, the estimated residual water content for surface Sphagnum samples, while on average lower in hummocks (0.082 m 3  m -3 ) versus hollows (0.087 m 3  m -3 ), increased from WET (0.058 m 3  m -3 ) to INT (0.088 m 3  m -3 ) to DRY (0.108 m 3  m -3 ) which has important implications for moisture stress under conditions of persistent WT drawdown. Given the potential importance of microtopographic succession for altering peatland hydraulic structure, our findings point to the need for a better understanding of what controls the relative height and proportional coverage of hummocks in relation to long-term disturbance-response dynamics. This article is protected by copyright. All rights reserved.
    Print ISSN: 0885-6087
    Electronic ISSN: 1099-1085
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Published by Wiley-Blackwell
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  • 15
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    Variation in hospital rates of induction of labour: a population-based record linkage study (2015)
    BMJ Publishing
    In: BMJ Open
    Details
    Publication Date: 2015-09-04
    Description: Objectives To examine interhospital variation in rates of induction of labour (IOL) to identify potential targets to reduce high rates of practice variation. Design Population-based record linkage cohort study. Setting New South Wales, Australia, 2010–2011. Participants All women with live births of ≥24 weeks gestation in 72 hospitals. Primary outcome measure Variation in hospital IOL rates adjusted for differences in case-mix, according to 10 mutually exclusive groups derived from the Robson caesarean section classification; groups were categorised by parity, plurality, fetal presentation, prior caesarean section and gestational age. Results The overall IOL rate was 26.7% (46 922 of 175 444 maternities were induced), ranging from 9.7% to 41.2% (IQR 21.8–29.8%) between hospitals. Nulliparous and multiparous women at 39–40 weeks gestation with a singleton cephalic birth were the greatest contributors to the overall IOL rate (23.5% and 20.2% of all IOL respectively), and had persisting high unexplained variation after adjustment for case-mix (adjusted hospital IOL rates ranging from 11.8% to 44.9% and 7.1% to 40.5%, respectively). In contrast, there was little variation in interhospital IOL rates among multiparous women with a singleton cephalic birth at ≥41 weeks gestation, women with singleton non-cephalic pregnancies and women with multifetal pregnancies. Conclusions 7 of the 10 groups showed high or moderate unexplained variation in interhospital IOL rates, most pronounced for women at 39–40 weeks gestation with a singleton cephalic birth. Outcomes associated with divergent practice require determination, which may guide strategies to reduce practice variation.
    Keywords: Open access, Epidemiology, Obgyn
    Electronic ISSN: 2044-6055
    Topics: Medicine
    Published by BMJ Publishing
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  • 16
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    Views on mandatory reporting of impaired health practitioners by their treating practitioners: a qualitative study from Australia (2016)
    BMJ Publishing
    In: BMJ Open
    Details
    Publication Date: 2016-12-21
    Description: Objective To explore the views and experiences of health sector professionals in Australia regarding a new national law requiring treating practitioners to report impaired health practitioners whose impairments came to their attention in the course of providing treatment. Method We conducted a thematic analysis of in-depth, semistructured interviews with 18 health practitioners and 4 medicolegal advisors from Australia's 6 states, each of whom had experience with applying the new mandatory reporting law in practice. Results Interviewees perceived the introduction of a mandatory reporting law as a response to failures of the profession to adequately protect the public from impaired practitioners. Mandatory reporting of impaired practitioners was reported to have several benefits: it provides treating practitioners with a ‘lever’ to influence behaviour, offers protections to those who make reports and underscores the duty to protect the public from harm. However, many viewed it as a blunt instrument that did not sufficiently take account of the realities of clinical practice. In deciding whether or not to make a report, interviewees reported exercising clinical discretion, and being influenced by three competing considerations: protection of the public, confidentiality of patient information and loyalty to their profession. Conclusions Competing ethical considerations limit the willingness of Australian health practitioners to report impaired practitioner-patients under a mandatory reporting law. Improved understanding and implementation of the law may bolster the public protection offered by mandatory reports, reduce the need to breach practitioner-patient confidentiality and help align the law with the loyalty that practitioners feel to support, rather than punish, their impaired colleagues.
    Keywords: Open access, Health policy, Legal and forensic medicine, Medical education and training, Mental health, Public health, Qualitative research
    Electronic ISSN: 2044-6055
    Topics: Medicine
    Published by BMJ Publishing
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