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The safety issue of lithium-ion batteries is a crucial factor limiting their large-scale application. Therefore, it is of practical significance to evaluate the impact of their overcharge behavior because of the severe levels of oxygen release of cathode materials during this process. Herein, by combining a variety of in situ techniques of spectroscopy and electron microscopy, this work studies the structural degradation of LiNi0.8Co0.1Mn0.1O2 (NCM811) accompanying the oxygen release in the overcharge process. It is observed that a small amount of O2 evolves from the initial surface at ≈4.7 V. When charging to a higher voltage (≈5.5 V), a large amount of O2 evolves on the newly formed surface due to the occurrence of microcracks. Based on experimental results and theoretical calculations, it is determined that the oxygen release mainly occurs in the near-surface regions, where the remaining oxygen vacancies accumulate to create voids. To suppress the oxygen release, single-crystalline NCM811 with integrated structure is introduced and serves as a cathode, which can effectively inhibit morphology destruction and reduce the activation of lattice oxygen in the surface region. These findings provide a theoretical basis and effective strategy for improving the safety performance of Ni-rich cathode materials in practical applications.

Objectives: To evaluate the influence of inversion time (TI) on the precision of myocardial late gadolinium enhancement (LGE) quantification using synthetic inversion recovery (IR) imaging in patients with myocardial infarction (MI). Methods: Fifty-three patients with suspected prior MI underwent 1.5-T cardiac MRI with conventional magnitude (MagIR) and phase-sensitive IR (PSIR) LGE imaging and T1 mapping at 15 min post-contrast. T1-based synthetic MagIR and PSIR images were calculated with a TI ranging from −100 to +150 ms at 5-ms intervals relative to the optimal TI (TI0). LGE was quantified using a five standard deviation (5SD) and full width at half-maximum (FWHM) thresholds. Measurements were compared using one-way analysis of variance. Results: The MagIRsy technique provided precise assessment of LGE area at TIs ≥ TI0, while precision was decreased below TI0. The LGE area showed significant differences at ≤ −25 ms compared to TI0 using 5SD (P < 0.001) and at ≤ −65 ms using the FWHM approach (P < 0.001). LGE measurements did not show significant difference over the analysed TI range in the PSIRsy images using either of the quantification methods. Conclusions: T1 map-based PSIRsy images provide precise quantification of MI independent of TI at the investigated time point post-contrast. MagIRsy-based MI quantification is precise at TI0 and at longer TIs while showing decreased precision at TI values below TI0. Key Points: • Synthetic IR imaging retrospectively generates LGE images at any theoretical TI • Synthetic IR imaging can simulate the effect of TI on LGE quantification • Fifteen minutes post-contrast MagIRsyaccurately quantifies infarcts from TI0to TI0 + 150 ms • Fifteen minutes post-contrast PSIRsyprovides precise infarct size independent of TI • Synthetic IR imaging has further advantages in reducing operator dependence.

Objectives: To assess the accuracy and efficiency of a threshold-based, semi-automated cardiac MRI segmentation algorithm in comparison with conventional contour-based segmentation and aortic flow measurements. Methods: Short-axis cine images of 148 patients (55 ± 18 years, 81 men) were used to evaluate left ventricular (LV) volumes and mass (LVM) using conventional and threshold-based segmentations. Phase-contrast images were used to independently measure stroke volume (SV). LV parameters were evaluated by two independent readers. Results: Evaluation times using the conventional and threshold-based methods were 8.4 ± 1.9 and 4.2 ± 1.3 min, respectively (P < 0.0001). LV parameters measured by the conventional and threshold-based methods, respectively, were end-diastolic volume (EDV) 146 ± 59 and 134 ± 53 ml; end-systolic volume (ESV) 64 ± 47 and 59 ± 46 ml; SV 82 ± 29 and 74 ± 28 ml (flow-based 74 ± 30 ml); ejection fraction (EF) 59 ± 16 and 58 ± 17 %; and LVM 141 ± 55 and 159 ± 58 g. Significant differences between the conventional and threshold-based methods were observed in EDV, ESV, and LVM mesurements; SV from threshold-based and flow-based measurements were in agreement (P > 0.05) but were significantly different from conventional analysis (P < 0.05). Excellent inter-observer agreement was observed. Conclusions: Threshold-based LV segmentation provides improved accuracy and faster assessment compared to conventional contour-based methods. Key Points: • Threshold-based left ventricular segmentation provides time-efficient assessment of left ventricular parameters • The threshold-based method can discriminate between blood and papillary muscles • This method provides improved accuracy compared to aortic flow measurements as a reference

Objectives: To evaluate the image quality of coronary CT angiography (CCTA) in obese patients using a 3rd generation, dual-source CT scanner. Methods: We retrospectively evaluated 102 overweight and obese patients who had undergone CCTA. Studies were performed with 3rd generation dual-source CT, prospectively ECG-triggered acquisition at 120 kV, and automated tube current modulation. Advanced modeled iterative reconstruction was used. Patients were divided into three BMI groups: 1)25–29.9 kg/m2; 2)30–39.9 kg/m2; 3) ≥ 40 kg/m2. Vascular attenuation in the coronary arteries was measured. Contrast-to-noise ratio (CNR) was calculated. Image quality was subjectively evaluated using five-point scales. Results: Image quality was considered diagnostic in 97.6 % of examinations. CNR was consistently adequate in all groups but decreased for groups 2 and 3 in comparison to group 1 as well as for group 3 compared to group 2 (p = 0.001, respectively). Subjective image quality was significantly higher in group 1 compared to group 3 (attenuation proximal: 4.8 ± 0.4 vs. 4.4 ± 0.6, p = 0.011; attenuation distal: 4.5 ± 0.7 vs. 4.0 ± 0.8, p = 0.019; noise: 4.7 ± 0.6 vs. 3.8 ± 0.7, p < 0.001). The mean effective dose was 9.5 ± 3.9 mSv for group 1, 11.4 ± 4.7 mSv for group 2 and 14.0 ± 6.4 mSv for group 3. Conclusion: Diagnostic image quality can be routinely obtained at CCTA in obese patients with 3rd generation DSCT at 120 kV. Key Points: • Diagnostic CCTA can be routinely performed in obese patients with 3rdgeneration DSCT. • 120-kV tube voltage allows diagnostic image quality in patients with BMI > 40 kg/m2. • 80-ml contrast medium can be administered without significant decline in vascular attenuation.

Purpose: To evaluate the impact of an advanced monoenergetic (ME) reconstruction algorithm on CT coronary stent imaging in a phantom model. Materials and methods: Three stents with lumen diameters of 2.25, 3.0 and 3.5 mm were examined with a third-generation dual-source dual-energy CT (DECT). Tube potential was set at 90/Sn150 kV for DE and 70, 90 or 120 kV for single-energy (SE) acquisitions and advanced modelled iterative reconstruction was used. Overall, 23 reconstructions were evaluated for each stent including three SE acquisitions and ten advanced and standard ME images with virtual photon energies from 40 to 130 keV, respectively. In-stent luminal diameter was measured and compared to nominal lumen diameter to determine stent lumen visibility. Contrast-to-noise ratio was calculated. Results: Advanced ME reconstructions substantially increased lumen visibility in comparison to SE for stents ≤3 mm. 130 keV images produced the best mean lumen visibility: 86 % for the 2.25 mm stent (82 % for standard ME and 64 % for SE) and 82 % for the 3.0 mm stent (77 % for standard ME and 69 % for SE). Mean DLP for SE 120 kV and DE acquisitions were 114.4 ± 9.8 and 58.9 ± 2.2 mGy × cm, respectively. Conclusion: DECT with advanced ME reconstructions improves the in-lumen visibility of small stents in comparison with standard ME and SE imaging. Key Points: • An advanced image-based monoenergetic reconstruction algorithm improves lumen visualization in stents ≤3.0 mm. • Application of high keV reconstructions significantly improves in-stent lumen visualization. • DECT acquisition resulted in 49 % radiation dose reduction compared with 120 kV SE.

Transcatheter aortic valve replacement (TAVR) is an increasingly used alternative to surgical aortic valve replacement in patients with severe aortic stenosis and prohibitive perioperative risk. Several studies have shown an improved clinical outcome and lower rate of complications with TAVR in this patient population. Furthermore, TAVR has shown promising results in patients at elevated risk from surgical aortic valve replacement. Because of the endovascular nature of this technique, comprehensive preprocedural assessment of the aortic root and vascular access path is crucial. Although echocardiography is still commonly performed to assess the aortic root, cross-sectional imaging modalities are increasingly used given their superior results in the diagnostic accuracy of TAVR measurements. In particular, computed tomography (CT) is gaining an increasing role in pre-TAVR imaging because of fast 3-dimensional assessment of aortic root anatomy and improvements in clinical outcome after TAVR when CT is used for pre-TAVR planning. However, different algorithms exist for matching valve size to the aortic root and left ventricular outflow tract, and these measurements may substantially impact valve prosthesis selection and postinterventional complication rates. Cardiac magnetic resonance may play a role especially in post-TAVR assessment, as it provides both anatomic information and blood flow dynamics. This article reviews multimodality imaging approaches to pre-TAVR aortic root size assessment, provides an overview of the impact on post-TAVR complications and clinical outcome, and describes recent techniques to reduce contrast material volume in TAVR assessment with CT.

T1 mapping with cardiac MRI has gained an important role in myocardial tissue characterization over the past decade as emerging technological developments enable reliable myocardial T1 assessment with a reasonably short acquisition time. Fast mapping approaches can acquire a single-slice T1 map in a single breath-hold even in patients with low compliance and low breath-holding capacity. Improvements in T1 mapping sequences have extended the clinical utility of this technique to a broad range of myocardial diseases. Indeed, native T1 mapping and extracellular volume fraction mapping seem to have superior value over conventional late gadolinium enhancement techniques in assessing certain myocardial diseases. Ongoing studies look to establish inter-vendor reference values, to further shorten the acquisition time, to develop 3D T1 mapping, and to improve reliability and reproducibility.

Minimally invasive mitral valve (MV) repair and replacement techniques have evolved as increasingly used alternatives to open heart surgery especially in patients unsuitable for surgery or at high perioperative risk. The vast majority of these techniques are still under development, and only a limited number of devices are approved for clinical use; however, they do show promising results in terms of minimizing complications and improving clinical outcome. The complex anatomy of the MV and the annulus complicates not only the development of devices for minimally invasive MV repair or replacement but also complicates preprocedural planning, which is mandatory for minimization of postprocedural complications. Although echocardiography still plays a crucial clinical role, cross-sectional imaging modalities such as coronary computed tomography (CCT) and cardiac magnetic resonance imaging (CMR) are increasingly gaining importance for preprocedural planning. Specifically, CCT seems to be more practicable for preinterventional planning and device sizing, whereas CMR has been shown useful in detecting increased risk for adverse clinical outcomes through delayed gadolinium enhancement and the monitoring of cardiac morphology and function in the framework of follow-up examinations. This article describes recent techniques currently available or under development for minimally invasive repair or replacement of the MV and reviews the current state of CCT and CMR imaging for preinterventional and postinterventional diagnostic workup.

Purpose: To evaluate a new dark-blood late gadolinium enhancement (LGE) technique called “T(Rho) And Magnetization transfer and INvErsion Recovery” (TRAMINER) for the ability to detect myocardial LGE versus standard “bright-blood” inversion recovery (SIR) imaging. Materials and Methods: This Institutional Review Board (IRB)-approved, Health Insurance Portability and Accountability Act (HIPAA)-compliant prospective study included 40 patients (62 ± 14 years [mean ± standard deviation (SD)], 29 males) with suspected myocardial infarction (MI) referred for the assessment of myocardial viability. The patients underwent a 1.5T cardiac magnetic resonance imaging (MRI) including postcontrast SIR and TRAMINER acquisitions. Normalized images were evaluated by two readers. Subjective (3-point Likert scale) and objective image qualities were compared using Mann–Whitney U-test and paired t-test, respectively. Interobserver agreement, LGE detection rate, and level of certainty were compared using Cohen's kappa, Wilcoxon-test, and Mann–Whitney U-test, respectively. Results are reported as mean ± SD or mean [95% confidence interval]. Results: Overall, image quality was rated similar between TRAMINER and SIR; however, TRAMINER performed better on a visual assessment of the ability to differentiate LGE from blood (Likert scale: 3.0 [3.0–3.0] vs. 2.0 [1.7–2.2], P < 0.0001). TRAMINER provided significantly higher signal intensity range (69.8 ± 10.2 vs. 9.6 ± 7.6, P < 0.0001) and a 4-fold higher signal intensity ratio (4.2 ± 1.9 vs. 1.1 ± 0.1, P < 0.0001) between LGE and blood signals. TRAMINER detected more patients (19/40 vs. 17/40) and segments (91/649 vs. 79/649) with LGE with higher level of certainty (2.9 [2.8–3.0] vs. 2.7 [2.5–2.8], P = 0.0185). Interobserver agreement was good to excellent for LGE detection. Conclusion: TRAMINER provides better contrast between LGE and blood and consequently may have increased ability to discriminate thin subendocardial and papillary mu