Effect of delayed acquisition times on Gadolinium-enhanced MRI of the presumably normal canine brain

A delay in imaging following intravenous contrast medium administration has been recommended to reduce misdiagnoses. However, the normal variation of contrast enhancement in dogs following a delay has not been characterized. Contrast enhanced MR imaging of 22 dogs was assessed, in terms of identification of normal anatomic structures, to investigate the variation associated with 10 minute delay between contrast medium administration and imaging. All dogs had a normal brain MR imaging study and unremarkable CSF. Specific ROIs were assessed both objectively, using computer software, and subjectively using three observers. Mean contrast enhancement greater than 10% was seen in the pituitary gland, choroid plexus, meninges, temporal muscle, trigeminal nerve and the trigeminal nerve root. Structures with an active blood-brain-barrier had minimal contrast enhancement (<6%). Enhancing structures had significantly more contrast enhancement at t=1min versus t=10min, except in temporal muscle, the trigeminal nerve and the trigeminal nerve root. Inter-observer agreement was moderate to good in favor of the initial post contrast T1w sequence. The observers found either no difference or poor agreement in identification of the non-vascular structures. Intra-observer agreement was very good with all vascular structures and most non-vascular structures. A degree of meningeal enhancement was a consistent finding. The initial acquisition had higher enhancement characteristics and observer agreement for some structures; however, contrast-to-noise was comparable in the delayed phase or not significantly different. We provide baseline references and suggest that the initial T1w post contrast sequence is preferable but not essential should a delayed post contrast T1w sequence be performed

Impact on maternity professionals of novel approaches to clinical audit feedback

We compared three approaches to feedback of clinical audit findings relating to miscarriage in 15 Scottish maternity services (printed report alone; report plus Action Planning Letter; report plus face-to-face Facilitated Action Planning). We surveyed clinicians to measure Theory of Planned Behaviour constructs (in the context of two audit criteria) before and after feedback (n=253) and assessed perceptions of the audit through in-depth interviews (n=17). Pre-feedback, clinicians had positive attitudes and strong subjective norms and intentions to comply, although perceived behavioural control was lower. Generally, positive attitudes, subjective norms and intentions increased after feedback but for one of the two criteria (providing a 7-day miscarriage service), perceived behavioural control decreased. No changes over time reached statistical significance and analysis of covariance (adjusting for pre-feedback scores) showed no consistent relationships between method of feedback and post-feedback construct scores. Interviews revealed positive perceptions of audit but frustration at lack of capacity to implement changes. While interventions which increased intensity of feedback proved feasible and acceptable to clinicians, we were unable to demonstrate that they increased intention to comply with audit criteria.This study was funded by NHS Quality Improvement Scotland

Rotationally Modulated X-ray Emission from T Tauri Stars

We have modelled the rotational modulation of X-ray emission from T Tauri stars assuming that they have isothermal, magnetically confined coronae. By extrapolating surface magnetograms we find that T Tauri coronae are compact and clumpy, such that rotational modulation arises from X-ray emitting regions being eclipsed as the star rotates. Emitting regions are close to the stellar surface and inhomogeneously distributed about the star. However some regions of the stellar surface, which contain wind bearing open field lines, are dark in X-rays. From simulated X-ray light curves, obtained using stellar parameters from the Chandra Orion Ultradeep Project, we calculate X-ray periods and make comparisons with optically determined rotation periods. We find that X-ray periods are typically equal to, or are half of, the optical periods. Further, we find that X-ray periods are dependent upon the stellar inclination, but that the ratio of X-ray to optical period is independent of stellar mass and radius.Comment: 10 pages, 8 figures, accepted for publication in MNRA

Age Related Changes in Cerebrovascular Reactivity and Its Relationship to Global Brain Structure

ACKNOWLEDGMENTS This study was funded by Alzheimer’s Research UK (ARUK) and the Aberdeen Biomedical Imaging Centre, University of Aberdeen. GDW, ADM and CS are part of the SINASPE collaboration (Scottish Imaging Network - A Platform for Scientific Excellence www.SINAPSE.ac.uk). The authors thank Gordon Buchan, Baljit Jagpal, Nichola Crouch, Beverly Maclennan and Katrina Klaasen for their help with running the experiment and Dawn Younie and Teresa Morris for their help with recruitment and scheduling. We also thank the residents of Aberdeen and Aberdeenshire, and further afield, for their generous participation.Peer reviewedPublisher PD

Diverse Supernova Sources for the r-Process

(Abridged) It is shown that a semi-quantitative agreement with the gross solar r-process abundance pattern near and above mass number A=130 can be obtained by a superposition of two distinctive kinds of supernova r-process events. These correspond to a low frequency case L and a high frequency case H, which takes into account the low abundance of I129 and the high abundance of Hf182 in the early solar nebula. The lifetime of Hf182 associates the events in case H with the most common Type II supernovae. These events would be mainly responsible for the r-process nuclei near and above A=195. They would also make a significant amount of the nuclei between A=130 and 195, including Hf182, but very little I129. In order to match the solar r-process abundance pattern and to satisfy the I129 and Hf182 constraints, the events in case L, which would make the r-process nuclei near A=130 and the bulk of those between A=130 and 195, must occur 10 times less frequently but eject 10--20 times more r-process material in each event. We speculate that the usual neutron star remnants, and hence prolonged ejection of r-process material, are associated with the events in case L, whereas the more frequently occurring events in case H have ejection of other r-process material terminated by black hole formation during the neutrino cooling phase of the protoneutron star.Comment: 23 pages, AAS LATEX, 8 Postscript figure

Rapid neutron capture in supernova explosions

Rapid neutron capture in supernova explosion

Long-Lasting Tumor Response in Patients with Panitumumab Monotherapy for Chemorefractory Metastatic Colorectal Carcinoma – A Report of Two Cases

Background: Second as well as higher-line therapies have a significant influence on progression-free and overall survival of metastatic colorectal cancer patients. However, treatment of late-stage disease remains suboptimal. Therefore, the introduction of new, effective and well-tolerated agents is of major importance. Case Reports: Here we describe the cases of 2 patients with metastatic KRAS wild-type colorectal cancer who received a fourth-line monotherapy with panitumumab after failure of 5-fluorouracil, irinotecan, oxaliplatin, and bevacizumab. Results: Both patients achieved a partial remission, and for 11.5 and 18 months, respectively, they had a stable disease with initial reduction in the tumor marker carcinoembryonic antigen. Both patients reported a good tolerability of the treatment with improved quality of life (compared to receiving combined chemotherapy). Conclusion: Panitumumab monotherapy is an effective and well tolerated treatment of metastatic colorectal cancer in extensively pretreated KRAS wild-type patients. Our data have shown a response to panitumumab monotherapy for more than 11 months