Alternative technique using dual source CT imaging for assessment of myocardial perfusion

AbstractPurposeTo elucidate the diagnostic role of multidetector DSCT for the assessment of myocardial perfusion in correlation with coronary luminal integrity in a single CT scan while both tubes were operated in single energy mode.Methods and materialThirty-five patients were subjected to single acquisition contrast-enhanced, ECG-gated DSCT of the heart at rest. Postprocessing was performed generating two image sets: coronary CT angiographic images (cCTA) and myocardial perfusion images (CTP) for respective correlative assessment of coronary luminal integrity and myocardial perfusion. Perfusion defect was detected subjectively using gray scale images and the color coded first pass and color overlaid late enhancement (color attenuation) images were used for semi-objective evaluation and final objective and quantitative confirmation by density measurement.ResultsSignificant correlation and good agreement between the findings of DSCT myocardial perfusion and the findings of stenosis and its degree on cCTA on a segmental basis is noted with Cohen’s Kappa=0.67 and prevalence and bias adjusted Kappa=0.71 emphasizing the high diagnostic value of DSCT myocardial perfusion as compared to cCTA as the gold reference standard.ConclusionWe propose that comprehensive evaluation of coronary artery morphology and myocardial perfusion in patients with CAD could be achieved by single reproducible non-invasive contrast enhanced CT acquisition using DSCT scanners while operated in single energy mode with high sensitivity, specificity and diagnostic accuracy, it also has the potential to be the first, independent and stand out imaging choice in such field

Modeling and characterization of a linear piezomotor

This paper presents the modeling and characterization of a novel class of piezoelectric linear motors. The motor relies in its operation on a set of piezoelectric bimorphs which are sequentially activated to linearly move a drive rod along spring loaded rollers. Emphasis in this paper is placed on studying the dynamic behavior of this class of piezoelectric motors, both theoretically and experimentally, in an effort to predict the piezomotor response to various loads and excitation schemes. To this end, a numerical model has been developed to simulate the dynamics of the piezoelectric bimorphs comprising the piezomotor. Friction between the bimorph elements and the drive rod are handled using an appropriate friction model. Experimental testing of the motor is carried out to validate the predictions of the theoretical model. This effort aims ultimately at demonstrating the feasibility of employing this class of piezoelectric actuators in driving smart snake robots in order to use them as a simple and reliable mobility platform.King Saud Universit

Geomagnetic phenomena observed by a temporal station at Ulu-Slim, Malaysia during the storm of March 27, 2017

A 3-axis fluxgate magnetometer was temporally setup for continuous recording during March 2017 at 3о 54’ 6” N, 101о 29’ 41” E, Ulu-Slim, Malaysia. On March 27th, a magnetic storm has been triggered by energetic solar wind emitted from a coronal hole on the sun that impacted the magnetosphere until the end of the measurement campaign on March 29th. The values measured at a sampling rate of 600 Hz are averaged to get a 1 Hz record from March 26 16:00 LT to March 29 12:00 LT. The 1 second data set is studied to deduce all magnetic phenomena captured during the magnetic storm. An overview of the complete record indicates the start of the storm and a complete absence of the typical diurnal variation of the total-field intensity on March 28. The diurnal variations are eliminated by subtracting a moving average of 100 samples from the recorded values. The residual shows a clear amplification of pulsations with the start of the storm. Pulsations enhancement are common around noon and is continuous on March 28th due to magnetotail activities during local night. Magnetospheric breathing as compression and expansion of the magnetosphere at long periods of 20 to 40 min is captured twice during the storm. An obvious occurrence of magnetotail reconnection is deduced by a sudden, steep increase of the total magnetic field with 50 nT at 01:30 LT on March 28. We conclude that the continuous recording of the magnetic field components provides very useful information about what processes are ongoing in space and how it might affect the logistics on the ground. The implementation of similar magnetometers as continuous observation stations would be of crucial benefits for Malaysia in both basic scientific and environmental aspects

Exploring the cost-effectiveness of high versus low perioperative fraction of inspired oxygen in the prevention of surgical site infections among abdominal surgery patients in three low- and middle-income countries

Background: This study assessed the potential cost-effectiveness of high (80–100%) vs low (21–35%) fraction of inspired oxygen (FiO2) at preventing surgical site infections (SSIs) after abdominal surgery in Nigeria, India, and South Africa. Methods: Decision-analytic models were constructed using best available evidence sourced from unbundled data of an ongoing pilot trial assessing the effectiveness of high FiO2, published literature, and a cost survey in Nigeria, India, and South Africa. Effectiveness was measured as percentage of SSIs at 30 days after surgery, a healthcare perspective was adopted, and costs were reported in US dollars ($). Results: High FiO2 may be cost-effective (cheaper and effective). In Nigeria, the average cost for high FiO2 was$216 compared with $222 for low FiO2 leading to a −$6 (95% confidence interval [CI]: −$13 to −$1) difference in costs. In India, the average cost for high FiO2 was $184 compared with$195 for low FiO2 leading to a −$11 (95$15 to −$6) difference in costs. In South Africa, the average cost for high FiO2 was$1164 compared with $1257 for low FiO2 leading to a −$93 (95% CI: −$132 to −$65) difference in costs. The high FiO2 arm had few SSIs, 7.33% compared with 8.38% for low FiO2, leading to a −1.05 (95% CI: −1.14 to −0.90) percentage point reduction in SSIs. Conclusion: High FiO2 could be cost-effective at preventing SSIs in the three countries but further data from large clinical trials are required to confirm this