Cultivating Institutional Capacities for Learning Analytics

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138371/1/he20243.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138371/2/he20243_am.pd

PET attenuation coefficients from CT images: experimental evaluation of the transformation of CT into PET 511-keV attenuation coefficients

The CT data acquired in combined PET/CT studies provide a fast and essentially noiseless source for the correction of photon attenuation in PET emission data. To this end, the CT values relating to attenuation of photons in the range of 40-140keV must be transformed into linear attenuation coefficients at the PET energy of 511keV. As attenuation depends on photon energy and the absorbing material, an accurate theoretical relation cannot be devised. The transformation implemented in the Discovery LS PET/CT scanner (GE Medical Systems, Milwaukee, Wis.) uses a bilinear function based on the attenuation of water and cortical bone at the CT and PET energies. The purpose of this study was to compare this transformation with experimental CT values and corresponding PET attenuation coefficients. In 14 patients, quantitative PET attenuation maps were calculated from germanium-68 transmission scans, and resolution-matched CT images were generated. A total of 114 volumes of interest were defined and the average PET attenuation coefficients and CT values measured. From the CT values the predicted PET attenuation coefficients were calculated using the bilinear transformation. When the transformation was based on the narrow-beam attenuation coefficient of water at 511keV (0.096cm-1), the predicted attenuation coefficients were higher in soft tissue than the measured values. This bias was reduced by replacing 0.096cm-1 in the transformation by the linear attenuation coefficient of 0.093cm-1 obtained from germanium-68 transmission scans. An analysis of the corrected emission activities shows that the resulting transformation is essentially equivalent to the transmission-based attenuation correction for human tissue. For non-human material, however, it may assign inaccurate attenuation coefficients which will also affect the correction in neighbouring tissu

Contemporary spinal cord protection during thoracic and thoracoabdominal aortic surgery and endovascular aortic repair: a position paper of the vascular domain of the European Association for Cardio-Thoracic Surgery†

Ischaemic spinal cord injury (SCI) remains the Achilles heel of open and endovascular descending thoracic and thoracoabdominal repair. Neurological outcomes have improved coincidentially with the introduction of neuroprotective measures. However, SCI (paraplegia and paraparesis) remains the most devastating complication. The aim of this position paper is to provide physicians with broad information regarding spinal cord blood supply, to share strategies for shortening intraprocedural spinal cord ischaemia and to increase spinal cord tolerance to transitory ischaemia through detection of ischaemia and augmentation of spinal cord blood perfusion. This study is meant to support physicians caring for patients in need of any kind of thoracic or thoracoabdominal aortic repair in decision-making algorithms in order to understand, prevent or reverse ischaemic SCI. Information has been extracted from focused publications available in the PubMed database, which are cohort studies, experimental research reports, case reports, reviews, short series and meta-analyses. Individual chapters of this position paper were assigned and after delivery harmonized by Christian D. Etz, Ernst Weigang and Martin Czerny. Consequently, further writing assignments were distributed within the group and delivered in August 2014. The final version was submitted to the EJCTS for review in September 201

The future of aortic surgery in Europe†

At least every ten years, each specialty should reflect upon its past, its present and its future, in order to be able to reconfirm the direction in which it is headed, to adopt suggestions from inside and outside and, consequently, to improve. As such, the aim of this manuscript is to provide the interested reader with an overview of how aortic surgery and (perhaps more accurately) aortic medicine has evolved in Europe, and its present standing; also to provide a glimpse into the future, trying to disseminate the thoughts of a group of people actively involved in the development of aortic medicine in Europe, namely the Vascular Domain of the European Association of Cardio-Thoracic Surgery (EACTS

An Analysis of the TRANSITION Study

Funding Information: This study was funded by Novartis . Funding Information: This study was funded by Novartis. The authors thank Tripti Sahu of Novartis Healthcare Pvt. Ltd. for providing medical writing support in accordance with Good Publication Practice (GPP 2022) guidelines (https://www.ismpp.org/gpp-2022). Publisher Copyright: © 2023 The AuthorsBackground: Treatment of patients with heart failure with reduced ejection fraction (HFrEF) and renal dysfunction (RD) is challenging owing to the risk of further deterioration in renal function, especially after acute decompensated HF (ADHF). Methods and Results: We assessed the effect of RD (estimated glomerular filtration rate of ≥30 to <60 mL/min/1.73 m2) on initiation, up-titration, and tolerability of sacubitril/valsartan in hemodynamically stabilized patients with HFrEF admitted for ADHF (RD, n = 476; non-RD, n = 483). At week 10, the target dose of sacubitril/valsartan (97/103 mg twice daily) was achieved by 42% patients in RD subgroup vs 54% in non-RD patients (P < .001). Sacubitril/valsartan was associated with greater estimated glomerular filtration rate improvements in RD subgroup than non-RD (change from baseline least squares mean 4.1 mL/min/1.73 m2, 95% confidence interval 2.2–6.1, P < .001). Cardiac biomarkers improved significantly in both subgroups; however, compared with the RD subgroup, the improvement was greater in those without RD (N-terminal pro-brain natriuretic peptide, −28.6% vs −44.8%, high-sensitivity troponin T −20.3% vs −33.9%) (P < .001). Patients in the RD subgroup compared with those without RD experienced higher rates of hyperkalemia (16.3% vs 6.5%, P < .001), investigator-reported cardiac failure (9.7% vs 5.6%, P = .029), and renal impairment (6.4% vs 2.1%, P = .002). Conclusions: Most patients with HFrEF and concomitant RD hospitalized for ADHF tolerated early initiation of sacubitril/valsartan and showed significant improvements in estimated glomerular filtration rate and cardiac biomarkers. Clinical Trial Registration: NCT02661217.proofepub_ahead_of_prin

Association between exercise frequency with renal and cardiovascular outcomes in diabetic and non-diabetic individuals at high cardiovascular risk

Background: Guidelines recommend physical activity to reduce cardiovascular (CV) events. The association between physical activity and progression of chronic kidney disease (CKD) with and without diabetes is unknown. We assessed the association of self-reported physical activity with renal and CV outcomes in high-risk patients aged≥55 years over a median follow-up of 56 months in post-hoc analysis of a previously randomized trial program. Methods: Analyses were done with Cox regression analysis, mixed models for repeated measures, ANOVA and χ2 - test. 31,312 patients, among them 19,664 with and 11,648 without diabetes were analyzed. Results: Physical activity was inversely associated with renal outcomes (doubling of creatinine, end-stage kidney disease (ESRD)) and CV outcomes (CV death, myocardial infarction, stroke, heart failure hospitalization). Moderate activity (at least 2 times/week to every day) was associated with lower risk of renal outcomes and lower incidence of new albuminuria (p<0.0001 for both) compared to lower exercise levels. Similar results were observed for those with and without diabetes without interaction for renal outcomes (p=0.097–0.27). Physical activity was associated with reduced eGFR decline with a moderate association between activity and diabetes status (p=0.05). Conclusions: Moderate physical activity was associated with improved kidney outcomes with a threshold at two sessions per week. The association of physical activity with renal outcomes did not meaningfully difer with or without diabetes but absolute beneft of activity was even greater in people with diabetes. Thus, risks were similar between those with diabetes undertaking high physical activity and those without diabetes but low physical activity. Clinical trial registration: http://clinicaltrials.gov.uniqueidentifer:NCT00153101

Mobile phones and head tumours. The discrepancies in cause-effect relationships in the epidemiological studies - how do they arise?

The uncertainty about the relationship between the use of mobile phones (MPs: analogue and digital cellulars, and cordless) and the increase of head tumour risk can be solved by a critical analysis of the methodological elements of both the positive and the negative studies. Results by Hardell indicate a cause/effect relationship: exposures for or latencies from 65 10 years to MPs increase by up to 100% the risk of tumour on the same side of the head preferred for phone use (ipsilateral tumours) - which is the only one significantly irradiated - with statistical significance for brain gliomas, meningiomas and acoustic neuromas. On the contrary, studies published under the Interphone project and others produced negative results and are characterised by the substantial underestimation of the risk of tumour. However, also in the Interphone studies a clear and statistically significant increase of ipsilateral head tumours (gliomas, neuromas and parotid gland tumours) is quite common in people having used MPs since or for 65 10 years. And also the metaanalyses by Hardell and other Authors, including only the literature data on ipsilateral tumours in people having used MPs since or for 65 10 years - and so also part of the Interphone data - still show statistically significant increases of head tumours

Sensorimotor function of the cervical spine in healthy volunteers

© 2015 The Authors. Abstract Background Sensorimotor mechanisms are important for controlling head motion. However, relatively little is known about sensorimotor function in the cervical spine. This study investigated how age, gender and variations in the test conditions affect measures of position sense, movement sense and reflex activation in cervical muscles. Methods Forty healthy volunteers (19M/21F, aged 19-59 years) participated. Position sense was assessed by determining repositioning errors in upright and flexed neck postures during tests performed in 25%, 50% and 75% cervical flexion. Movement sense was assessed by detecting thresholds to passive flexion and extension at velocities between 1 and 25 s- 1. Reflexes were assessed by determining the latency and amplitude of reflex activation in trapezius and sternocleidomastoid muscles. Reliability was evaluated from intraclass correlation coefficients. Findings Mean repositioning errors ranged from 1.5 to 2.6, were greater in flexed than upright postures (P = 0.006) and in people aged over 25 years (P = 0.05). Time to detect head motion decreased with increasing velocity (P < 0.001) and was lower during flexion than extension movements (P = 0.002). Reflexes demonstrated shorter latency (P < 0.001) and greater amplitude (P = 0.009) in trapezius compared to sternocleidomastoid, and became slower and weaker with age. None of the measures were influenced by gender. Reliability was good for movement sense measures, but was influenced by the test conditions when assessing position sense. Interpretation Increased repositioning errors and slower reflexes in older subjects suggest that sensorimotor function in the cervical spine becomes impaired with age. In position sense tests, reliability was influenced by the test conditions with mid-range flexion movements, performed in standing, providing the most reliable measurements