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- Stuijfzand, Wijnand J, et al.
(author)
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Relative flow reserve derived from quantitative perfusion imaging may not outperform stress myocardial blood flow for identification of hemodynamically significant coronary artery disease
- 2015
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In: Circulation Cardiovascular Imaging. - 1941-9651 .- 1942-0080. ; 8:1
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Journal article (peer-reviewed)abstract
- BACKGROUND: Quantitative myocardial perfusion imaging is increasingly used for the diagnosis of coronary artery disease. Quantitative perfusion imaging allows to noninvasively calculate fractional flow reserve (FFR). This so-called relative flow reserve (RFR) is defined as the ratio of hyperemic myocardial blood flow (MBF) in a stenotic area to hyperemic MBF in a normal perfused area. The aim of this study was to assess the value of RFR in the detection of significant coronary artery disease.METHODS AND RESULTS: From a clinical population of patients with suspected coronary artery disease who underwent oxygen-15-labeled water cardiac positron emission tomography and invasive coronary angiography, 92 patients with single- or 2-vessel disease were included. Intermediate lesions (diameter stenosis, 30%-90%; n=75) were interrogated by FFR. Thirty-eight (41%) vessels were deemed hemodynamically significant (>90% stenosis or FFR≤0.80). Hyperemic MBF, coronary flow reserve, and RFR were lower for vessels with a hemodynamically significant lesion (2.01±0.78 versus 2.90±1.16 mL·min(-1)·g(-1); P<0.001, 2.27±1.03 versus 3.10±1.29; P<0.001, and 0.67±0.23 versus 0.93±0.15; P<0.001, respectively). The correlation between RFR and FFR was moderate (r=0.54; P<0.01). Receiver operator characteristic curve analysis showed an area under the curve of 0.82 for RFR, which was not significantly higher compared with that for hyperemic MBF and coronary flow reserve (0.76; P=0.32 and 0.72; P=0.08, respectively).CONCLUSIONS: Noninvasive estimation of FFR by quantitative perfusion positron emission tomography by calculating RFR is feasible, yet only a trend toward a slight improvement of diagnostic accuracy compared with hyperemic MBF assessment was determined.
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- Vierinen, J., et al.
(author)
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Space debris observation potential with EISCAT 3D
- 2018
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In: 2ND URSI ATLANTIC RADIO SCIENCE MEETING (AT-RASC). - : IEEE. - 9789082598735
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Conference paper (peer-reviewed)abstract
- We investigate the capabilities of the next generation ionospheric research radar EISCAT 3D (E3D) for space debris observations. We have used the current projected design of E3D as basis of this study. To model the performance of E3D for space debris observations, we have included basic radar equation based error analysis for range and range-rate observations. Because the radar will be multi-static, it is also capable of observing instantaneous three-dimensional vector velocities and positions by observing round-trip range and range-rate between the transmitter and three receiver sites. We have included error estimates for both of the the three-dimensional position and three-dimensional vector velocity observations. To estimate the fraction of total debris that can be observed with E3D, we have used the MASTER model. We have also investigated effects of radio wave propagation. E3D uses a relatively low VHF frequency (233 MHz), which experiences more radio wave propagation effects than more conventional higher frequency space surveillance radars. Our modeling shows that ionospheric ray-bending and group delay are severe enough that these effects need to be modeled in order to determine accurate orbital elements. As EISCAT 3D is an ionospheric research radar, there will be high quality ionospheric electron density measurements that can be utilized for radio propagation modeling.
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