Impact of cardiac magnetic resonance imaging on human lymphocyte DNA integrity

Aims Magnetic resonance (MR) imaging is widely used for diagnostic imaging in medicine as it is considered a safe alternative to ionizing radiation-based techniques. Recent reports on potential genotoxic effects of strong and fast switching electromagnetic gradients such as used in cardiac MR (CMR) have raised safety concerns. The aim of this study was to analyse DNA double-strand breaks (DSBs) in human blood lymphocytes before and after CMR examination. Methods and results In 20 prospectively enrolled patients, peripheral venous blood was drawn before and after 1.5 T CMR scanning. After density gradient cell separation of blood samples, DNA DSBs in lymphocytes were quantified using immunofluorescence microscopy and flow cytometric analysis. Wilcoxon signed-rank testing was used for statistical analysis. Immunofluorescence microscopic and flow cytometric analysis revealed a significant increase in median numbers of DNA DSBs in lymphocytes induced by routine 1.5 T CMR examination. Conclusion The present findings indicate that CMR should be used with caution and that similar restrictions may apply as for X-ray-based and nuclear imaging techniques in order to avoid unnecessary damage of DNA integrity with potential carcinogenic effec

Introducing coherent time control to cavity magnon-polariton modes

By connecting light to magnetism, cavity magnon-polaritons (CMPs) can link quantum computation to spintronics. Consequently, CMP-based information processing devices have emerged over the last years, but have almost exclusively been investigated with single-tone spectroscopy. However, universal computing applications will require a dynamic and on-demand control of the CMP within nanoseconds. Here, we perform fast manipulations of the different CMP modes with independent but coherent pulses to the cavity and magnon system. We change the state of the CMP from the energy exchanging beat mode to its normal modes and further demonstrate two fundamental examples of coherent manipulation. We first evidence dynamic control over the appearance of magnon-Rabi oscillations, i.e., energy exchange, and second, energy extraction by applying an anti-phase drive to the magnon. Our results show a promising approach to control building blocks valuable for a quantum internet and pave the way for future magnon-based quantum computing research

Coronary computed tomography angiography with model-based iterative reconstruction using a radiation exposure similar to chest X-ray examination

Aims To evaluate the feasibility and image quality of coronary computed tomography angiography (CCTA) acquisition with a submillisievert fraction of effective radiation dose using model-based iterative reconstruction (MBIR) for noise reduction. Methods and results In 42 patients undergoing standard low-dose (100-120 kV; 450-700 mA) and additional ultra-low-dose CCTA (80-100 kV; 150-210 mA) reconstructed with MBIR, segmental image quality was graded on a four-point scale [(i): non-evaluative, (ii): good, (iii): adequate, and (iv): excellent]. Signal-to-noise ratio (SNR) was calculated dividing left main artery (LMA) and right coronary artery (RCA) attenuation by the aortic root noise. Over a wide range of body mass index (18-40 kg/m2), the estimated median radiation dose exposure was 1.19 mSv [interquartile range (IQR): 1.07-1.30 mSv] for standard and 0.21 mSv (IQR: 0.18-0.23 mSv) for ultra-low-dose CCTA (P < 0.001). The median image quality score per segment was 3.5 (IQR: 3.0-4.0) in standard CCTA vs. 3.5 (IQR: 2.5-4.0) in ultra-low dose with MBIR (P = 0.29). Diagnostic image quality (scores 2-4) was found in 98.7 vs. 97.8% coronary segments (P = 0.36). Introduction of MBIR for ultra-low-dose CCTA resulted in a significant increase in SNR (P < 0.001) for LMA (from 15 ± 5 to 29 ± 7) and RCA (from 14 ± 4 to 27 ± 6) despite 82% dose reduction. Conclusion Coronary computed tomography angiography acquisition with diagnostic image quality is feasible at an ultra-lowradiation dose of 0.21 mSv, e.g. in the range reported for a postero-anterior and lateral chest X-ra

First experience with single-source, dual-energy CCTA for monochromatic stent imaging

Aims Single-source, dual-energy coronary computed tomography angiography (CCTA) with monochromatic image reconstruction allows significant noise reduction. The aim of the study was to evaluate the impact of monochromatic CCTA image reconstruction on coronary stent imaging, as the latter is known to be affected by artefacts from highly attenuating strut material resulting in artificial luminal narrowing. Methods and results Twenty-one patients with 62 stents underwent invasive coronary angiography and single-source, dual-energy CCTA after stent implantation. Standard polychromatic images as well as eight monochromatic series (50, 60, 70, 80, 90, 100, 120, and 140 keV) were reconstructed for each CCTA. Signal and noise were measured within the stent lumen and in the aortic root. Mean in-stent luminal diameter was assessed in all CCTA reconstructions and compared with quantitative invasive coronary angiography (QCA). Luminal attenuation was higher in the stent than in the aortic root throughout all monochromatic reconstructions (P < 0.001). An increase in monochromatic energy was associated with a decrease in luminal attenuation values (P < 0.001). The mean in-stent luminal diameter underestimation by monochromatic CCTA compared with QCA was 90% at low monochromatic energy (50 keV) and improved to 37% at high monochromatic (140 keV) reconstruction while stent diameter was underestimated by 39% with standard CCTA. Conclusion Monochromatic CCTA can be used reliably in patients with coronary stents. However, reconstructions with energies below 80 keV are not recommended as the blooming artefacts are most pronounced at such low energies, resulting in up to 90% stent diameter underestimatio

Amplitude and frequency sensing of microwave fields with a superconducting transmon qudit

Experiments with superconducting circuits require careful calibration of the applied pulses and fields over a large frequency range. This remains an ongoing challenge as commercial semiconductor electronics are not able to probe signals arriving at the chip due to its cryogenic environment. Here, we demonstrate how the on-chip amplitude and frequency of a microwave signal can be inferred from the ac Stark shifts of higher transmon levels. In our time-resolved measurements we employ Ramsey fringes, allowing us to detect the amplitude of the systems transfer function over a range of several hundreds of MHz with an energy sensitivity on the order of 10−4. Combined with similar measurements for the phase of the transfer function, our sensing method can facilitate pulse correction for high fidelity quantum gates in superconducting circuits. Additionally, the potential to characterize arbitrary microwave fields promotes applications in related areas of research, such as quantum optics or hybrid microwave systems including photonic, mechanical or magnonic subsystems

Is spontaneous coronary artery dissection (SCAD) related to local anatomy and hemodynamics? An exploratory study

AIMS: Spontaneous coronary artery dissection (SCAD) is an increasingly diagnosed cause of myocardial infarction with unclear pathophysiology. The aim of the study was to test if vascular segments site of SCAD present distinctive local anatomy and hemodynamic profiles. METHODS: Coronary arteries with spontaneously healed SCAD (confirmed by follow-up angiography) underwent three-dimensional reconstruction, morphometric analysis with definition of vessel local curvature and torsion, and computational fluid dynamics (CFD) simulations with derivation of time-averaged wall shear stress (TAWSS) and topological shear variation index (TSVI). The (reconstructed) healed proximal SCAD segment was visually inspected for co-localization with curvature, torsion, and CFD-derived quantities hot spots. RESULTS: Thirteen vessels with healed SCAD underwent the morpho-functional analysis. Median time between baseline and follow-up coronary angiograms was 57 (interquartile range [IQR] 45-95) days. In seven cases (53.8%), SCAD was classified as type 2b and occurred in the left anterior descending artery or near a bifurcation. In all cases (100%), at least one hot spot co-localized within the healed proximal SCAD segment, in 9 cases (69.2%) ≥ 3 hot spots were identified. Healed SCAD in proximity of a coronary bifurcation presented lower TAWSS peak values (6.65 [IQR 6.20-13.20] vs. 3.81 [2.53-5.17] Pa, p = 0.008) and hosted less frequently TSVI hot spots (100% vs. 57.1%, p = 0.034). CONCLUSION: Vascular segments of healed SCAD were characterized by high curvature/torsion and WSS profiles reflecting increased local flow disturbances. Hence, a pathophysiological role of the interaction between vessel anatomy and shear forces in SCAD is hypothesized

CT coronary angiography: impact of adapted statistical iterative reconstruction (ASIR) on coronary stenosis and plaque composition analysis

To assess the impact of adaptive statistical iterative reconstruction (ASIR) on coronary plaque volume and composition analysis as well as on stenosis quantification in high definition coronary computed tomography angiography (CCTA). We included 50 plaques in 29 consecutive patients who were referred for the assessment of known or suspected coronary artery disease (CAD) with contrast-enhanced CCTA on a 64-slice high definition CT scanner (Discovery HD 750, GE Healthcare). CCTA scans were reconstructed with standard filtered back projection (FBP) with no ASIR (0 %) or with increasing contributions of ASIR, i.e. 20, 40, 60, 80 and 100 % (no FBP). Plaque analysis (volume, components and stenosis degree) was performed using a previously validated automated software. Mean values for minimal diameter and minimal area as well as degree of stenosis did not change significantly using different ASIR reconstructions. There was virtually no impact of reconstruction algorithms on mean plaque volume or plaque composition (e.g. soft, intermediate and calcified component). However, with increasing ASIR contribution, the percentage of plaque volume component between 401 and 500 HU decreased significantly (p < 0.05). Modern image reconstruction algorithms such as ASIR, which has been developed for noise reduction in latest high resolution CCTA scans, can be used reliably without interfering with the plaque analysis and stenosis severity assessment

Coronary artery calcium quantification from contrast enhanced CT using gemstone spectral imaging and material decomposition

To explore the feasibility of coronary artery calcium (CAC) measurement from low-dose contrast enhanced coronary CT angiography (CCTA) as this may obviate the need for an unenhanced CT scan. 52 patients underwent unenhanced cardiac CT and prospectively ECG triggered contrast enhanced CCTA (Discovery HD 750, GE Healthcare, Milwaukee, WI, USA). The latter was acquired in single-source dual-energy mode [gemstone spectral imaging (GSI)]. Virtual unenhanced images were generated from GSI CCTA by monochromatic image reconstruction of 70 keV allowing selective iodine material suppression. CAC scores from virtual unenhanced CT were compared to standard unenhanced CT including a linear regression model. After iodine subtraction from the contrast enhanced CCTA the attenuation in the ascending aorta decreased significantly from 359 ± 61 to 54 ± 8 HU (P < 0.001), the latter comparing well to the value of 64 ± 55 HU found in the standard unenhanced CT (P = ns) confirming successful iodine subtraction. After introducing linear regression formula the mean values for Agatston, Volume and Mass scores of virtual unenhanced CT were 187 ± 321, 72 ± 114 mm(3), and 27 ± 46 mg/cm(3), comparing well to the values from standard unenhanced CT (187 ± 309, 72 ± 110 mm(3), and 27 ± 45 mg/cm(3)) yielding an excellent correlation (r = 0.96, r = 0.96, r = 0.92; P < 0.001). Mean estimated radiation dose revealed 0.83 ± 0.02 mSv from the unenhanced CT and 1.70 ± 0.53 mSv from the contrast enhanced CCTA. Single-source dual-energy scanning with GSI allows CAC quantification from low dose contrast enhanced CCTA by virtual iodine contrast subtraction

Sex differences in prehospital delays in patients with st-segment-elevation myocardial infarction undergoing percutaneous coronary intervention

BACKGROUND: Women with ST-segment-elevation myocardial infarction experience delays in reperfusion compared with men with little data on each time component from symptom onset to reperfusion. This study analyzed sex discrepancies in patient delays, prehospital system delays, and hospital delays. METHODS AND RESULTS: Consecutive patients with ST-segment-elevation myocardial infarction treated with percutaneous coronary intervention across 30 hospitals in the Victorian Cardiac Outcomes Registry (2013-2018) were analyzed. Data from the Ambulance Victoria Data warehouse were used to perform linkage to the Victorian Cardiac Outcomes Registry for all patients transported via emergency medical services (EMS). The primary end point was EMS call-to-door time (prehospital system delay). Secondary end points included symptom-to-EMS call time (patient delay), door-to-device time (hospital delay), 30-day mortality, major adverse cardiovascular events, and major bleeding. End points were analyzed according to sex and adjusted for age, comorbidities, cardiogenic shock, cardiac arrest, and symptom onset time. A total of 6330 (21% women) patients with ST-segment-elevation myocardial infarction were transported by EMS. Compared with men, women had longer adjusted geometric mean symptom-to-EMS call times (47.0 versus 44.0 minutes; P<0.001), EMS call-to-door times (58.1 versus 55.7 minutes; P<0.001), and door-to-device times (58.5 versus 54.9 minutes; P=0.006). Compared with men, women had higher 30-day mortality (odds ratio [OR], 1.38; 95% CI, 1.06-1.79; P=0.02) and major bleeding (OR, 1.54; 95% CI, 1.08-2.20; P=0.02). CONCLUSIONS: Female patients with ST-segment-elevation myocardial infarction experienced excess delays in patient delays, prehospital system delays, and hospital delays, even after adjustment for confounders. Prehospital system and hospital delays resulted in an adjusted excess delay of 10 minutes compared with men