Fractional flow reserve (FFR) computation from coronary computed tomography angiography (CTA) datasets (FFRCT) has emerged as a promising noninvasive test to assess hemodynamic severity of coronary ...artery disease (CAD), but has not yet been compared with traditional functional imaging.
The purpose of this study was to evaluate the diagnostic performance of FFRCT and compare it with coronary CTA, single-photon emission computed tomography (SPECT), and positron emission tomography (PET) for ischemia diagnosis.
This subanalysis involved 208 prospectively included patients with suspected stable CAD, who underwent 256-slice coronary CTA, 99mTc-tetrofosmin SPECT, 15OH2O PET, and routine 3-vessel invasive FFR measurements. FFRCT values were retrospectively derived from the coronary CTA images. Images from each modality were interpreted by core laboratories, and their diagnostic performances were compared using invasively measured FFR ≤0.80 as the reference standard.
In total, 505 of 612 (83%) vessels could be evaluated with FFRCT. FFRCT showed a diagnostic accuracy, sensitivity, and specificity of 87%, 90%, and 86% on a per-vessel basis and 78%, 96%, and 63% on a per-patient basis, respectively. Area under the receiver-operating characteristic curve (AUC) for identification of ischemia-causing lesions was significantly greater for FFRCT (0.94 and 0.92) in comparison with coronary CTA (0.83 and 0.81; p < 0.01 for both) and SPECT (0.70 and 0.75; p < 0.01 for both), on a per-vessel and -patient level, respectively. FFRCT also outperformed PET on a per-vessel basis (AUC 0.87; p < 0.01), but not on a per-patient basis (AUC 0.91; p = 0.56). In the intention-to-diagnose analysis, PET showed the highest per-patient and -vessel AUC followed by FFRCT (0.86 vs. 0.83; p = 0.157; and 0.90 vs. 0.79; p = 0.005, respectively).
In this study, FFRCT showed higher diagnostic performance than standard coronary CTA, SPECT, and PET for vessel-specific ischemia, provided coronary CTA images were evaluable by FFRCT, whereas PET had a favorable performance in per-patient and intention-to-diagnose analysis. Still, in patients in whom 3-vessel FFRCT could be analyzed, FFRCT holds clinical potential to provide anatomic and hemodynamic significance of coronary lesions.
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Abstract
Spin-orbit coupling plays an important role in the spin Hall effect and topological insulators. Bose-Einstein condensates with spin-orbit coupling show remarkable quantum phase transition. ...In this work we control an exciton polariton condensate – a macroscopically coherent state of hybrid light and matter excitations – by virtue of the Rashba-Dresselhaus (RD) spin-orbit coupling. This is achieved in a liquid-crystal filled microcavity where CsPbBr
3
perovskite microplates act as the gain material at room temperature. Specifically, we realize an artificial gauge field acting on the CsPbBr
3
exciton polariton condensate, splitting the condensate fractions with opposite spins in both momentum and real space. Besides the ground states, higher-order discrete polariton modes can also be split by the RD effect. Our work paves the way to manipulate exciton polariton condensates with a synthetic gauge field based on the RD spin-orbit coupling at room temperature.
Secretion of pulmonary surfactant in the alveoli of the lungs is essential to maintain lung function. Stretching of alveoli during lung inflation is the main trigger for surfactant secretion. Yet, ...the molecular mechanisms how mechanical distension of alveoli results in surfactant secretion are still elusive. The alveolar epithelium consists of alveolar epithelial type I (ATI) and surfactant secreting type II (ATII) cells. ATI, but not ATII cells, express caveolae, small plasma membrane invaginations that can respond to plasma membrane stresses and serve mechanotransductive roles. Within this study, we investigated the role of caveolae as mechanosensors in the alveolus. We generated a human caveolin‐1 knockout ATI cell (hAELVicav−/−) using CRISPR/Cas9. Wildtype (hAELViwt) and hAELVicav−/− cells grown on flexible membranes responded to increasing stretch amplitudes with rises in intracellular Ca2+. The response was less frequent and started at higher stretch amplitudes in hAELVicav−/− cells. Stretch‐induced Ca2+‐signals depended on Ca2+‐entry via piezo1 channels, localized within caveolae in hAELViwt and primary ATI cells. Ca2+‐entry via piezo1 activated pannexin‐1 hemichannels resulting in ATP release from ATI cells. ATP release was reduced in hAELVicav−/− cells. In co‐cultures resembling the alveolar epithelium, released ATP stimulated Ca2+ signals and surfactant secretion from neighboring ATII cells when co‐cultured with hAELViwt but not hAELVicav−/− cells. In summary, we propose that caveolae in ATI cells are mechanosensors within alveoli regulating stretch‐induced surfactant secretion from ATII cells.
Vortices are topological objects representing the circular motion of a fluid. With their additional degree of freedom, the vorticity, they have been widely investigated in many physical systems and ...different materials for fundamental interest and for applications in data storage and information processing. Vortices have also been observed in non-equilibrium exciton-polariton condensates in planar semiconductor microcavities. There they appear spontaneously or can be created and pinned in space using ring-shaped optical excitation profiles. However, using the vortex state for information processing not only requires creation of a vortex but also efficient control over the vortex after its creation. Here we demonstrate a simple approach to control and switch a localized polariton vortex between opposite states. In our scheme, both the optical control of vorticity and its detection through the orbital angular momentum of the emitted light are implemented in a robust and practical manner.
Abstract
Aims
Continuous thermodilution is a novel technique to quantify absolute coronary flow and microvascular resistance (MVR). Notably, intracoronary infusion of saline elicits maximal ...hyperaemia, obviating the need for adenosine. The primary aim of this study was to validate continuous thermodilution in humans by comparing invasive measurements to 15OH2O positron emission tomography (PET). As a secondary goal, absolute flow and MVR were compared between invasive measurements obtained with and without adenosine.
Methods and results
Twenty-five patients underwent coronary computed tomography angiography (CCTA), 15OH2O PET, and invasive assessment. Absolute coronary flow and MVR were measured in the left anterior descending and left circumflex artery using a dedicated infusion catheter and a temperature/pressure sensor-tipped guidewire. Invasive measurements were performed with and without adenosine. In order to compare invasive flow measurements with PET perfusion, subtending myocardial mass of the investigated vessels was derived from CCTA using the Voronoi algorithm. Invasive and non-invasive measurements of adenosine-induced hyperaemic flow and MVR showed strong correlation (r = 0.91; P < 0.001 for flow and r = 0.85; P < 0.001 for MVR) and good agreement intraclass correlation coefficient (ICC) = 0.90; P < 0.001 for flow and ICC = 0.79; P < 0.001 for MVR. Absolute flow and MVR also correlated well between measurements with and without adenosine (r = 0.97; P < 0.001 for flow and r = 0.98; P < 0.001 for MVR) and showed good agreement (ICC = 0.96; P < 0.001 for flow and ICC = 0.98; P < 0.001 for MVR).
Conclusions
Continuous thermodilution is an accurate method to measure absolute coronary flow and MVR, which is evidenced by strong agreement with 15OH2O PET derived flow and resistance. Absolute flow and MVR correlate highly between invasive measurements obtained with and without adenosine, which confirms that intracoronary infusion of room temperature saline elicits steady-state maximal hyperaemia.
Circularly polarized (CP) electroluminescence from organic light-emitting diodes (OLEDs) has aroused considerable attention for their potential in future display and photonic technologies. The ...development of CP-OLEDs relies largely on chiral-emitters, which not only remain rare owing to difficulties in design and synthesis but also limit the performance of electroluminescence. When the polarization (pseudospin) degrees of freedom of a photon interact with its orbital angular momentum, photonic spin-orbit interaction (SOI) emerges such as Rashba-Dresselhaus (RD) effect. Here, we demonstrate a chiral-emitter-free microcavity CP-OLED with a high dissymmetry factor (g
) and high luminance by embedding a thin two-dimensional organic single crystal (2D-OSC) between two silver layers which serve as two metallic mirrors forming a microcavity and meanwhile also as two electrodes in an OLED architecture. In the presence of the RD effect, the SOIs in the birefringent 2D-OSC microcavity result in a controllable spin-splitting with CP dispersions. Thanks to the high emission efficiency and high carrier mobility of the OSC, chiral-emitter-free CP-OLEDs have been demonstrated exhibiting a high g
of 1.1 and a maximum luminance of about 60000 cd/m
, which places our device among the best performing CP-OLEDs. This strategy opens an avenue for practical applications towards on-chip microcavity CP-OLEDs.
This study was designed to assess the prognostic value of pericoronary adipose tissue computed tomography attenuation (PCATa) beyond quantitative coronary computed tomography angiography ...(CCTA)–derived plaque volume and positron emission tomography (PET) determined ischemia.
Inflammation plays a crucial role in atherosclerosis. PCATa has been shown to assess coronary-specific inflammation and is of prognostic value in patients with suspected coronary artery disease (CAD).
A total of 539 patients who underwent CCTA and 15OH2O PET perfusion imaging because of suspected CAD were included. Imaging assessment included coronary artery calcium score (CACS), presence of obstructive CAD (≥50% stenosis) and high-risk plaques (HRPs), total plaque volume (TPV), calcified/noncalcified plaque volume (CPV/NCPV), PCATa, and myocardial ischemia. The endpoint was a composite of death and nonfatal myocardial infarction. Prognostic thresholds were determined for quantitative CCTA variables.
During a median follow-up of 5.0 (interquartile range: 4.7 to 5.0) years, 33 events occurred. CACS >59 Agatston units, obstructive CAD, HRPs, TPV >220 mm3, CPV >110 mm3, NCPV >85 mm3, and myocardial ischemia were associated with shorter time to the endpoint with unadjusted hazard ratios (HRs) of 4.17 (95% confidence interval CI: 1.80 to 9.64), 4.88 (95% CI: 1.88 to 12.65), 3.41 (95% CI: 1.72 to 6.75), 7.91 (95% CI: 3.05 to 20.49), 5.82 (95% CI: 2.40 to 14.10), 8.07 (95% CI: 3.33 to 19.55), and 4.25 (95% CI: 1.84 to 9.78), respectively (p < 0.05 for all). Right coronary artery (RCA) PCATa above scanner specific thresholds was associated with worse prognosis (unadjusted HR: 2.84; 95% CI: 1.44 to 5.63; p = 0.003), whereas left anterior descending artery and circumflex artery PCATa were not related to outcome. RCA PCATa above scanner specific thresholds retained is prognostic value adjusted for imaging variables and clinical characteristics associated with the endpoint (adjusted HR: 2.45; 95% CI: 1.23 to 4.93; p = 0.011).
Parameters associated with atherosclerotic burden and ischemia were more strongly associated with outcome than RCA PCATa. Nonetheless, RCA PCATa was of prognostic value beyond clinical characteristics, CACS, obstructive CAD, HRPs, TPV, CPV, NCPV, and ischemia.
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This study sought to assess the presence and morphological features of coronary plaques on optical coherence tomography (OCT) as the causes of myocardial infarction with nonobstructive coronary ...arteries (MINOCA).
Although coronary atherosclerosis has been postulated as a potential mechanism of MINOCA, the interaction between disrupted coronary plaques and myocardial injury remains unknown.
In a prospective study, consecutive patients with MI but without significant coronary stenosis (≥50%) at angiography underwent OCT and cardiac magnetic resonance (CMR) with late gadolinium-enhancement (LGE). The infarct-related artery (IRA) was identified by localization of ischemic-type LGE.
Thirty-eight MINOCA patients (mean age 62 ± 13 years, 55% female, 39% with ST-segment elevation) were enrolled. Maximal diameter stenosis was 35% by angiography, and 5 patients (13%) had normal angiogram results. Plaque disruption and coronary thrombus were observed in 9 patients (24%) and 7 patients (18%), respectively. Sixteen of 31 patients (52%) undergoing CMR showed LGE. Ischemic-type LGE was present in 7 patients (23%) and was more common in patients with than without plaque disruption (50% vs. 13%, respectively; p = 0.053) and coronary thrombus (67% vs. 12%, respectively; p = 0.014). In the per-lesion analysis, the IRA showed significantly more plaque disruption (40% vs. 6%; p = 0.02), thrombus (50% vs. 4%; p = 0.014), and thin-cap fibroatheroma (70% vs. 30%; p = 0.03) than the non-IRA.
Plaque disruption and thrombus are not uncommon in MI without obstructive coronary stenoses at angiography and may be associated with the presence and location of ischemic-type myocardial injury on CMR. OCT may be valuable in identifying atherosclerotic etiology in individuals with MINOCA. (Optical Coherence Tomography in Patients With Acute Myocardial Infarction and Nonobstructive Coronary Artery Disease SOFT-MI; NCT02783963).
Abstract
Aims
To evaluate the prognostic value of global and regional quantitative 15OH2O positron emission tomography (PET) perfusion.
Methods and results
In this retrospective study, 648 patients ...with suspected or known coronary artery disease (CAD) who underwent 15OH2O PET were followed for the occurrence of death and myocardial infarction (MI). Global and regional hyperaemic myocardial blood flow (hMBF) and coronary flow reserve (CFR) were obtained from 15OH2O PET. During median follow-up of 6.9 (5.0–7.9) years, 64 (9.9%) patients experienced the composite of death (36–5.6%) and MI (28–4.3%). Impaired global hMBF (<2.65 mL/min/g) and CFR (<2.88) were both significant prognostic factors for death/MI after adjusting for clinical characteristics (both P < 0.001). However, after adjusting for clinical parameters and the combined use of hMBF and CFR, only hMBF remained an independent prognostic factor (P = 0.04). For regional perfusion, both impaired hMBF (<2.10 mL/min/g) and CFR (<2.07) demonstrated prognostic value for events (both P < 0.001). Similarly, after adjusting for clinical characteristics and combined use of hMBF and CFR, only hMBF had independent prognostic value (P = 0.04). The combination of global and regional perfusion did not improve prognostic performance over either global (P = 0.55) or regional perfusion (P = 0.37) alone.
Conclusion
Global and regional hMBF and CFR were all prognostic factors for death and MI. However, for both global and regional perfusion, hMBF remained the only independent prognostic factor after adjusting for the combined use of hMBF and CFR. Additionally, integrating global and regional perfusion did not increase prognostic performance compared to either regional or global perfusion alone.
Optical Spectroscopy of Graphene Quantum Dots: The Case of C132 Riesen, Hans; Wiebeler, Christian; Schumacher, Stefan
The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory,
07/2014, Volume:
118, Issue:
28
Journal Article
Peer reviewed
We have reinvestigated the optical spectroscopy of C132 graphene quantum dots by absorption, selective fluorescence, excitation and time-resolved spectroscopy, the external heavy atom effect, and DFT ...based quantum chemical calculations. In particular, wavelength-selective photobleaching provides strong evidence for the assignment of the intrinsic absorption and emission features of the quantum dots and indicates that emissions observed at ∼670 and ∼630 nm and associated relatively narrow features that display vibrational progressions in the selective excitation spectra are due to different species. The emitting state that leads to a broad emission (1700 cm–1) centered around 750 nm appears to be a “near-dark” singlet state with a relatively long lifetime of ∼30 ns. Simulated spectra, based on the nuclear ensemble approach, are in qualitative agreement with this finding and indicate very low oscillator strengths with some significant electron-vibrational intensity borrowing.
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