The Feasibility, Tolerability, Safety, and Accuracy of Low-radiation Dynamic Computed Tomography Myocardial Perfusion Imaging With Regadenoson Compared With Single-photon Emission Computed Tomography

Objectives: Computed tomography (CT) myocardial perfusion imaging (CT-MPI) with hyperemia induced by regadenoson was evaluated for the detection of myocardial ischemia, safety, relative radiation exposure, and patient experience compared with single-photon emission computed tomography (SPECT) imaging. Materials and Methods: Twenty-four patients (66.5 y, 29% male) who had undergone clinically indicated SPECT imaging and provided written informed consent were included in this phase II, IRB-approved, and FDA-approved clinical trial. All patients underwent coronary CT angiography and CT-MPI with hyperemia induced by the intravenous administration of regadenoson (0.4 mg/5 mL). Patient experience and findings on CT-MPI images were compared to SPECT imaging. Results: Patient experience and safety were similar between CT-MPI and SPECT procedures and no serious adverse events due to the administration of regadenoson occurred. SPECT resulted in a higher number of mild adverse events than CT-MPI. Patient radiation exposure was similar during the combined coronary computed tomography angiography and CT-MPI (4.4 [2.7] mSv) and SPECT imaging (5.6 [1.7] mSv) (P-value 0.401) procedures. Using SPECT as the reference standard, CT-MPI analysis showed a sensitivity of 58.3% (95% confidence interval [CI]: 27.7-84.8), a specificity of 100% (95% CI: 73.5-100), and an accuracy of 79.1% (95% CI: 57.9-92.87). Low apparent sensitivity occurred when the SPECT defects were small and highly suspicious for artifacts. Conclusions: This study demonstrated that CT-MPI is safe, well tolerated, and can be performed with comparable radiation exposure to SPECT. CT-MPI has the benefit of providing both complete anatomic coronary evaluation and assessment of myocardial perfusion

The Canadian consortium for arctic data interoperability : an emerging polar information network

Established in 2015, the Canadian Consortium for Arctic Data Interoperability (CCADI) is an emerging initiative to develop an integrated Canadian arctic data anagement system that will facilitate information discovery, establish metadata and data sharing standards, enable interoperability among existing data infrastructures, and that will be accessible to a broad audience of users. Key to the CCADI vision are: standards and mechanisms for metadata interoperability and semantic interoperability; a distributed data exchange platform; streamlined data services with common entry, access, search, match, analysis, visualization and output tools; an intellectual property and sensitive data service; and data stewardship capacity. This will be a particularly challenging set of tasks given that the data planned for inclusion is multidisciplinary, in multiple types that range from sensor data to material artifacts, and, in some cases, confidential.publishedVersio

State of the climate in 2013

In 2013, the vast majority of the monitored climate variables reported here maintained trends established in recent decades. ENSO was in a neutral state during the entire year, remaining mostly on the cool side of neutral with modest impacts on regional weather patterns around the world. This follows several years dominated by the effects of either La Niña or El Niño events. According to several independent analyses, 2013 was again among the 10 warmest years on record at the global scale, both at the Earths surface and through the troposphere. Some regions in the Southern Hemisphere had record or near-record high temperatures for the year. Australia observed its hottest year on record, while Argentina and New Zealand reported their second and third hottest years, respectively. In Antarctica, Amundsen-Scott South Pole Station reported its highest annual temperature since records began in 1957. At the opposite pole, the Arctic observed its seventh warmest year since records began in the early 20th century. At 20-m depth, record high temperatures were measured at some permafrost stations on the North Slope of Alaska and in the Brooks Range. In the Northern Hemisphere extratropics, anomalous meridional atmospheric circulation occurred throughout much of the year, leading to marked regional extremes of both temperature and precipitation. Cold temperature anomalies during winter across Eurasia were followed by warm spring temperature anomalies, which were linked to a new record low Eurasian snow cover extent in May. Minimum sea ice extent in the Arctic was the sixth lowest since satellite observations began in 1979. Including 2013, all seven lowest extents on record have occurred in the past seven years. Antarctica, on the other hand, had above-average sea ice extent throughout 2013, with 116 days of new daily high extent records, including a new daily maximum sea ice area of 19.57 million km2 reached on 1 October. ENSO-neutral conditions in the eastern central Pacific Ocean and a negative Pacific decadal oscillation pattern in the North Pacific had the largest impacts on the global sea surface temperature in 2013. The North Pacific reached a historic high temperature in 2013 and on balance the globally-averaged sea surface temperature was among the 10 highest on record. Overall, the salt content in nearsurface ocean waters increased while in intermediate waters it decreased. Global mean sea level continued to rise during 2013, on pace with a trend of 3.2 mm yr-1 over the past two decades. A portion of this trend (0.5 mm yr-1) has been attributed to natural variability associated with the Pacific decadal oscillation as well as to ongoing contributions from the melting of glaciers and ice sheets and ocean warming. Global tropical cyclone frequency during 2013 was slightly above average with a total of 94 storms, although the North Atlantic Basin had its quietest hurricane season since 1994. In the Western North Pacific Basin, Super Typhoon Haiyan, the deadliest tropical cyclone of 2013, had 1-minute sustained winds estimated to be 170 kt (87.5 m s-1) on 7 November, the highest wind speed ever assigned to a tropical cyclone. High storm surge was also associated with Haiyan as it made landfall over the central Philippines, an area where sea level is currently at historic highs, increasing by 200 mm since 1970. In the atmosphere, carbon dioxide, methane, and nitrous oxide all continued to increase in 2013. As in previous years, each of these major greenhouse gases once again reached historic high concentrations. In the Arctic, carbon dioxide and methane increased at the same rate as the global increase. These increases are likely due to export from lower latitudes rather than a consequence of increases in Arctic sources, such as thawing permafrost. At Mauna Loa, Hawaii, for the first time since measurements began in 1958, the daily average mixing ratio of carbon dioxide exceeded 400 ppm on 9 May. The state of these variables, along with dozens of others, and the 2013 climate conditions of regions around the world are discussed in further detail in this 24th edition of the State of the Climate series. © 2014, American Meteorological Society. All rights reserved

Analysis of myocardial perfusion parameters in an ex-vivo porcine heart model using third generation dual-source CT

PURPOSE: To evaluate the relationship between fractional flow reserve (FFR)-determined coronary artery stenosis severity and myocardial perfusion parameters derived from dynamic myocardial CT perfusion imaging (CTP) in an ex-vivo porcine heart model. METHODS: Six porcine hearts were perfused according to Langendorff. Circulatory parameters such as arterial blood flow (ABF) (L/min), mean arterial pressure (MAP) (mmHg) and heart rate (bpm) were monitored. Using an inflatable cuff and monitored via a pressure wire, coronary artery stenoses of different FFR grades were created (no stenosis, FFR = 0.80, FFR = 0.70, FFR = 0.60, and FFR = 0.50). Third generation dual-source CT was used to perform dynamic CTP in shuttle mode at 70 kV. Using the AHA-16-segment model, myocardial blood flow (MBF) (mL/100 mL/min) and volume (MBV) (mL/100 mL) were analyzed using dedicated software for all ischaemic and non-ischaemic segments. RESULTS: During five successful experiments, ABF ranged from 0.8 to 1.2 L/min, MAP from 73 to 90 mmHg and heart rate from 83 to 115 bpm. Non-ischaemic and ischaemic segments showed significant differences in MBF for stenosis grades of FFR ≤ 0.70. At this degree of obstruction, median MBF was 79 (interquartile range [IQR]: 66-90) for non-ischaemic segments versus 56 mL/100 mL/min (IQR: 46-73) for ischaemic segments (p < 0.05). For MBV, a significant difference was found at FFR ≤ 0.80 with median MBV values of 7.6 (IQR: 7.0-8.3) and 7.1 mL/100 mL (IQR: 6.0-8.2) for non-ischaemic and ischaemic myocardial segments, respectively (p < 0.05). CONCLUSION: Artificial flow alterations in a Langendorff porcine heart model could be detected and measured by CTP-derived myocardial perfusion parameters and showed significant systematic correlation with stepwise flow reduction that permitted early detection of ischaemic myocardium. Additional research in clinical setting is required to develop absolute quantitative CTP

Contrast media injection protocol optimization for dual-energy coronary CT angiography. results from a circulation phantom

Objectives: To investigate the minimum iodine delivery rate (IDR) required to achieve diagnostic coronary attenuation (300 HU) with dual-energy coronary CTA. Methods: Acquisitions were performed on a circulation phantom with a third- generation dual-source CT scanner. Contrast media was injected for a fixed time whilst IDRs varied from 1.0 to 0.3 gI/s in 0.1-gI/s intervals. Noise-optimized virtual monoenergetic imaging (VMI+) reconstructions from 40 to 90 keV in 5 keV increments were generated. Contrast-to-noise ratio (CNR) and coronary HU were measured for each injection. Results: VMI+ from 40–70 keV reached diagnostic attenuation with at least one IDR. The minimum IDR achieving a diagnostic attenuation ranged from 0.4 gI/s at 40 keV (312.8 HU) to 1.0 gI/s at 70 keV (334.1 HU). Attenuation values reached with IDR of 1.0 gI/s were significantly higher at each keV level (p<0.001). CNR showed a near perfect correlation with the IDR (ρ≥0.962; p<0.001), the IDR of 1.0 gI/s provided the highest CNR at each keV level, achieving the highest overall value at 40 keV (54.0±3.1). Conclusions: IDRs from 0.4–1.0 gI/s associated with VMI+ from 40–70 keV provide diagnostic coronary attenuation with dual-energy coronary CTA. Key Points: • Iodine delivery rate (IDR) is a major determinant of contrast enhancement. • Low-keV noise-optimized monoenergetic images (VMI+) maximize iodine attenuation. • Low-keV VMI+ allows for lower IDRs while maintaining adequate coronary attenuation. • Lowest IDR to reach 300 HU was 0.4 gI/s, 40 keV VMI+

An Investigation of Production Workers’ Performance Variations and the Potential Impact of Attitudes

In most manufacturing systems the contribution of human labour remains a vital element that affects overall performance and output. Workers’ individual performance is known to be a product of personal attitudes towards work. However, in current system design processes, worker performance variability is assumed to be largely insignificant and the potential impact of worker attitudes is ignored. This paper describes a field study that investigated the extent to which workers’ production task cycle times vary and the degree to which such variations are associated with attitude differences. Results show that worker performance varies significantly, much more than is assumed by contemporary manufacturing system designers and that this appears to be due to production task characteristics. The findings of this research and their implications are discussed

CT angiography for planning transcatheter aortic valve replacement using automated tube voltage selection: image quality and radiation exposure

Purpose To assess image quality and accuracy of CT angiography (CTA) for transcatheter aortic valve replacement (TAVR) planning performed with 3rd generation dual-source CT (DSCT). Material and methods We evaluated 125 patients who underwent TAVR-planning CTA on 3rd generation DSCT. A two-part protocol was performed including retrospectively ECG-gated coronary CTA (CCTA) and prospectively ECG-triggered aortoiliac CTA using 60&nbsp;mL of contrast medium. Automated tube voltage selection and advanced iterative reconstruction were applied. Effective dose (ED), signal-to-noise (SNR) and contrast-to-noise ratios (CNR) were calculated. Five-point scales were used for subjective image quality analysis. In patients who underwent TAVR, sizing parameters were obtained. Results Image quality was rated good to excellent in 97.6% of CCTA and 100% of aortoiliac CTAs. CTA studies at &gt;100&nbsp;kV showed decreased objective image quality compared to 70–100&nbsp;kV (SNR, all p&nbsp;≤&nbsp;0.0459; CNR, all p&nbsp;≤&nbsp;0.0462). Mean ED increased continuously from 70 to &gt;100&nbsp;kV (CCTA: 4.5&nbsp;±&nbsp;1.7&nbsp;mSv–13.6&nbsp;±&nbsp;2.9&nbsp;mSv, all p&nbsp;≤&nbsp;0.0233; aortoiliac CTA: 2.4&nbsp;±&nbsp;0.9&nbsp;mSv–6.8&nbsp;±&nbsp;2.7&nbsp;mSv, all p&nbsp;≤&nbsp;0.0414). In 39 patients TAVR was performed and annulus diameter was within the recommended range in all patients. No severe cardiac or vascular complications were noted. Conclusion 3rd generation DSCT provides diagnostic image quality in TAVR-planning CTA and facilitates reliable assessment of TAVR device and delivery option while reducing radiation dose

CT myocardial perfusion. State of the science

Non-invasive cardiac imaging has rapidly evolved during the last decade due to advancements in CT technologies. Coronary CT angiography (CCTA) has been shown to reliably assess the coronary anatomy and has established itself as the non-invasive imaging technique with the highest sensitivity and specificity in the evaluation of patients with suspected coronary artery disease (CAD). However, this technique has previously been limited to a pure anatomical assessment. CT myocardial perfusion imaging (CT-MPI) is an increasingly rediscovered CT technique able to provide functional assessment of the myocardium and, when combined with CTA, allows for a comprehensive assessment of the coronary arteries, all done within a single modality. This review will describe the current knowledge in CT-MPI, including the varying techniques as well as a summary of the current literature

Optimal timing of image acquisition for arterial first pass CT myocardial perfusion imaging

Purpose: To determine the optimal timing of arterial first pass computed tomography (CT) myocardial perfusion imaging (CTMPI) based on dynamic CTMPI acquisitions. Methods and materials: Twenty-five patients (59 + 8.4 years, 14 male)underwent adenosine-stress dynamic CTMPI on second-generation dual-source CT in shuttle mode (30 s at 100 kV and 300 mAs). Stress perfusion magnetic resonance imaging (MRI) was used as reference standard for differentiation of non-ischemic and ischemic segments. The left ventricle (LV) wall was manually segmented according to the AHA 16-segment model. Hounsfield units (HU) in myocardial segments and ascending (AA) and descending aorta (AD) were monitored over time. Time difference between peak AA and peak AD and peak myocardial enhancement was calculated, as well as the, time delay from fixed HU thresholds of 150 and 250 HU in the AA and AD to a minimal difference of 15 HU between normal and ischemic segments. Furthermore, the duration of the 15 HU difference between ischemic and non-ischemic segments was calculated. Results: Myocardial ischemia was observed by MRI in 10 patients (56.3 +/- 9.0 years; 8 male). The delay between the maximum HU in the AA and AD and maximal HU in the non-ischemic segments was 2.8 s [2.2-4.3] and 0.0 s [0.0-2.8], respectively. Differentiation between ischemic and non-ischemic myocardial segments in CT was best during a time window of 8.6 +/- 3.8 s. Time delays for AA triggering were 4.5 s [2.2-5.6] and 2.2 s [0-2.8] for the 150 HU and 250 HU thresholds, respectively. While for AD triggering, time delays were 2.4 s [0.0-4.8] and 0.0 s [-2.2-2.6] for the 150 HU and 250 HU thresholds, respectively. Conclusion: In CTMPI, the differentiation between normal and ischemic myocardium is best accomplished during a time interval of 8.6 + 3.8 s. This time window can be utilized by a test bolus or bolus tracking in the AA or AD using the time delays identified here. (C) 2016 Elsevier Ireland Ltd. All rights reserved