Reliability of phase-specific outcome measurements in change-of-direction tests using a motorized resistance device

This study aims to determine test-retest reliability of phase-specific information during initial acceleration, deceleration, and re-acceleration phases of different change-of-direction (CoD) tests using a motorized resistance device (MRD). A total of 21 participants (16 males and five females, with mean age of 22.3 ± 3.9 years, body mass of 75.2 ± 6.9 kg, height of 177.9 ± 6.8 cm) completed the modified 505 (m505), 10-0-5, and 15-0-5 CoD tests on four different test sessions while exposed to an external load (3 kg) provided by the MRD. Outcome variables included overall and phase-specific kinetic (force, power, and impulse) and kinematic (time, distance, velocity, and acceleration/deceleration) data during the initial acceleration, deceleration, and re-acceleration phases. The deceleration and re-acceleration phases were further divided into two subphases, namely, early and late subphases, using 50% of maximum velocity. Reliability was assessed using an intraclass correlation coefficient (ICC), coefficient of variation (CV), typical error (TE), and minimal detectable change (MDC). Good to excellent ICC values (>0.75) and acceptable (<10%) to good (<5%) CV values were observed for most outcome measurements. Specifically, 80.1% (822 out of 1,026) of all variables showed good or better relative reliability (i.e., ICC ≥ 0.75), while 97.0% (995 out of 1,026) of all variables showed acceptable or better absolute reliability (i.e., CV < 10%). In conclusion, the present study demonstrates that the MRD can obtain reliable phase-specific outcome measurements across different CoD tests, providing coaches and researchers with new opportunities to advance our understanding of CoD ability and inform more advanced CoD training prescriptions.

The influence of arm positions on mechanical dyssynchrony measured by gated myocardial perfusion imaging

Background

In routine procedures, patient's arms are positioned above their heads to avoid potential attenuation artifacts and reduced image quality during gated myocardial perfusion imaging (G-MPI). However, it is difficult to achieve this action in the acute period following pacemaker implantation. This study aimed to explore the influence of arm positioning on myocardial perfusion imaging (MPI) in different types of heart disease.

Methods

This study was conducted retrospectively. A total of 123 patients were enrolled and underwent resting G-MPI using a standard protocol with arms positioned above their heads and again with their arms at their sides. All individuals were divided into 3 groups: the normal group, the obstructive coronary artery disease (O-CAD) group, and the dilated cardiomyopathy (DCM) group. The G-MPI data were measured by QGS software and Emory Reconstruction Toolbox, including left ventricular ejection fraction (LVEF), end-diastolic volume (EDV), end-systolic volume (ESV), extent, total perfusion deficit (TPD), summed rest score (SRS), scar burden, phase standard deviation (SD), and phase histogram bandwidth (BW).

Results

In total, extent, TPD, EDV, ESV, LVEF, systolic SD, systolic BW, diastolic SD, and diastolic BW were all significantly different between the 2 arm positions (all P<0.01). On the Bland-Altman analysis, both EDV and ESV with the arm-down position were significantly underestimated (P<0.001). Meanwhile, TPD, extent, and LVEF with the arm-down position were significantly overestimated (P<0.05). Systolic SD, systolic BW, diastolic SD, and diastolic BW were systematically overestimated (P<0.001). In the DCM group (n=52), EDV, ESV, systolic SD, systolic BW, diastolic SD, and diastolic BW were identified as significantly different by the paired t-test between the 2 arm positions (P<0.05). In the O-CAD group (n=32), scar burden, ESV, LVEF, and diastolic BW were significantly different between the 2 arm positions (P<0.05).

Conclusions

Systolic and diastolic dyssynchrony parameters and most left ventricular (LV) functional parameters were significantly influenced by arm position in both normal individuals and patients with heart failure (HF) with different pathophysiologies. More attention should be given to LV dyssynchrony data during clinical evaluation of cardiac resynchronization therapy (CRT) implantation procedure.

Simultaneous assessment of left ventricular mechanical dyssynchrony using integrated 13N-ammonia PETMR system: direct comparison of PET phase analysis and MR feature tracking

BACKGROUND

To compare phase analysis with positron emission tomography (PA) and magnetic resonance feature tracking derived myocardial strain (FT) for left ventricular (LV) mechanical dyssynchrony using PETMR system in patients with ischemic heart disease.

METHODS AND RESULTS

Patients who underwent rest-pharmacological stress 13N ammonia PETMR were enrolled. Histogram bandwidth (BW) and phase standard deviation (PSD) were compared to global longitudinal, long axis radial, short axis circumferential, and radial strain (GLS, GRS, SA Circ, and SA Rad) obtained from FT. LV dyssynchrony index (SDI) derived from PA and FT were compared. BW and PSD showed significant correlations with FT (a Pearson's coefficient r = 0.64, P < .0001, and r = 0.51, P < .0001 for SA Circ; r = 0.67, P < .0001, and r = 0.74, P < .0001 for GLS; r = - 0.60, P < .0001, r = - 0.61, P < .0001 for SA Rad; r = - 0.62, P < .0001, and r = - 0.68, P < .0001 for GRS, respectively). Bland-Altman plots for SDI showed a preferable agreement (95% limit of agreement - 0.12 to 0.075, - 0.20 to 0.098, - 0.38 to 0.077, and - 0.37 to 0.032; bias 0.0068 ± 0.056, 0.026 ± 0.068, 0.11 ± 0.088, and 0.13 ± 0.079 for SA Circ, SA Rad, GLS, and GRS, respectively).

CONCLUSION

In simultaneous acquisition using PETMR, comparison of PET phase analysis and MR strain showed a good correlation.

The Identity and Mineral Composition of Natural, Plant-Derived and Artificial Sweeteners

The qualitative X-ray phase analysis of natural and artificial food sweeteners was applied to trace the authenticity of such food additives. The mineral composition of different sweeteners commonly added to foods was studied to estimate their mineral profiles and assess the risk related to the toxic elements intake caused by sweetener consumption. The concentration of twenty elements (Ag, Al, B, Ba, Bi, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Pb, Sr, Ti, V, and Zn) was measured using the inductively coupled plasma-optical emission spectroscopy (ICP-OES) method after the representative samples were wet-digested with a concentrated nitric acid and hydrogen peroxide mixture in a closed-vessel microwave-assisted system. Differences between the mineral compositions of the examined sweeteners were statistically evaluated and discussed. The relationships between the concentrations of the elements determined in the analyzed sweeteners were also investigated. The successful application of the X-ray powder diffraction method proved the identity of all investigated sweeteners; all the analyzed products contained the expected sweetening agent. The results of the quantification of all the elements in the examined sweeteners indicated that these products cannot be considered nutritionally dense. Hence, the presence of toxic elements like Cd, Cr, Ni, and Pb distinctly indicates the need to test such products to guarantee their quality and ensure consumer safety.

The Prospects of Using Structural Phase Analysis of Microcalcifications in Breast Cancer Diagnostics

The detection of microcalcifications in the breast by mammography is of great importance for the early diagnostics of breast cancer. This study aimed to establish the basic morphological and crystal-chemical properties of microscopic calcifications and their impact on breast cancer tissue. During the retrospective study, 55 out of 469 breast cancer samples had microcalcifications. The expression of the estrogen and progesterone receptors and Her2-neu showed no significant difference from the non-calcified samples. An in-depth study of 60 tumor samples revealed a higher expression of osteopontin in the calcified breast cancer samples (p ˂ 0.01). The mineral deposits had a hydroxyapatite composition. Within the group of calcified breast cancer samples, we detected six cases of colocalization of oxalate microcalcifications together with biominerals of the usual "hydroxyapatite" phase composition. The simultaneous presence of calcium oxalate and hydroxyapatite was accompanied by a different spatial localization of microcalcifications. Thus, the phase compositions of microcalcifications could not be used as criteria for the differential diagnostics of breast tumors.

Cardiac remodelling in association with left ventricular dyssynchrony and systolic dysfunction in patients with coronary artery disease

BACKGROUND

In patients with coronary artery disease (CAD), ischaemic cardiomyopathy may result in progressive cardiac remodelling and left ventricular (LV) dysfunction. Myocardial perfusion imaging (MPI) can be used to quantify LV size and shape, mechanical dyssynchrony (LVMD) and ejection fraction (EF) as well as myocardial ischaemia and injury extents. We investigated the prevalence of LV remodelling (LVR) in patients with CAD and the relationship between LVR, LVMD and EF.

METHODS

Three hundred twenty-six patients with CAD were evaluated. The EF and end-diastolic volume (EDV) were measured using MPI. LVMD was assessed using phase analysis. LVR was characterised according to LV dilatation or increased shape indices (systolic shape index [SIES] and diastolic shape index [SIED]).

RESULTS

LVR were observed in 41% of CAD patients. EDV, SIES and SIED were larger in patients with LVMD or low EF. After adjustment for age, sex and infarct and ischaemia extents, phase histogram bandwidth correlated with EDV (r = 0.218) and SIES (r = 0.266) and EF correlated with EDV (r = -0.535), SIES (r = -0.554) and SIED (r = -0.217, p < 0.001 for all).

CONCLUSIONS

LVR is frequently seen in patients with CAD and may be detected even before the development of symptomatic heart failure. A large LV volume and a more spherical-shaped LV were associated with LVMD and low EF, highlighting the close relationships between remodelling and systolic dyssynchrony and dysfunction. MPI is useful for assessing LVR by providing information about LV size and shape, which changes from an ellipsoid towards a spherical form in the development of ischaemic cardiomyopathy.

A Review on Heat Treatment of Cast Iron: Phase Evolution and Mechanical Characterization

The isothermal heat treatment process has been identified as a unique process of fabricating exceptional graphite cast iron due to its remarkable mechanical properties, such as excellent machinability, toughness, and high level of ultimate tensile strength. Austempered ductile iron (ADI), ductile iron (DI), and gray cast iron (GCI), known as spheroidal cast irons, are viable alternative materials compared to traditional steel casting, as well as aluminum casting. The graphite nodules from the microstructures of DI, ADI, and GCI are consistently encompassed by acicular ferrite and carbon-saturated austenite in the matrix, forming a distinctive ausferritic structure. All these materials are extensively used in the fabrication of engine sleeves, engine blocks, valves, gears, and camshafts in the automobile sector. With relative motion and outward loads, these components are regularly exposed to surface contact. In this project, it was observed that austempering temperature and a shorter holding period could also be used to manufacture needle-like ferrite platelets for austempered ductile iron (ADI) and other graphite cast irons. To overcome the brittleness challenges and catastrophic failures encountered by applied loads in present-day applications, it is essential to comprehend the isothermal treatments, morphological behaviors, phase analyses, processing techniques, and mechanical properties needed to properly incorporate these materials into future designs. This review article provides detailed information on the characterization and relevant potential mechanisms of ADI, DI, and GCI.

The assessment of left ventricular mechanical dyssynchrony from gated 99mTc-tetrofosmin SPECT and gated 18F-FDG PET by QGS: a comparative study

BACKGROUND

Due to partly conflicting studies, further research is warranted with the QGS software package, with regard to the performance of gated FDG PET phase analysis as compared to gated MPS as well as the establishment of possible cut-off values for FDG PET to define dyssynchrony.

METHODS

Gated MPS and gated FDG PET datasets of 93 patients were analyzed with the QGS software. BW, Phase SD, and Entropy were calculated and compared between the methods. The performance of gated PET to identify dyssynchrony was measured against SPECT as reference standard. ROC analysis was performed to identify the best discriminator of dyssynchrony and to define cut-off values.

RESULTS

BW and Phase SD differed significantly between the SPECT and PET. There was no significant difference in Entropy with a high linear correlation between methods. There was only moderate agreement between SPECT and PET to identify dyssynchrony. Entropy was the best single PET parameter to predict dyssynchrony with a cut-off point at 62%.

CONCLUSION

Gated MPS and gated FDG PET can assess LVMD. The methods cannot be used interchangeably. Establishing reference ranges and cut-off values is difficult due to the lack of an external gold standard. Further prospective research is necessary.

Clinical impacts of scar reduction on gated myocardial perfusion SPECT after cardiac resynchronization therapy

BACKGROUND

It had not been reported that myocardial scar shown on gated myocardial perfusion SPECT (GMPS) might reduce after cardiac resynchronization therapy (CRT). In this study, we aim to investigate the clinical impact and characteristic of scar reduction (SR) after CRT.

METHODS AND RESULTS

Sixty-one heart failure patients following standard indication for CRT received twice GMPS as pre- and post-CRT evaluations. The patients with an absolute reduction of scar ≥ 10% after CRT were classified as the SR group while the rest were classified as the non-SR group. The SR group (N = 22, 36%) showed more improvement on LV function (∆LVEF: 18.1 ± 12.4 vs 9.4 ± 9.9 %, P = 0.007, ∆ESV: - 91.6 ± 52.6 vs - 38.1 ± 46.5 mL, P < 0.001) and dyssynchrony (ΔPSD: - 26.19 ± 18.42 vs - 5.8 ± 23.0°, P < 0.001, Δ BW: - 128.7 ± 82.8 vs - 25.2 ± 109.0°, P < 0.001) than non-SR group (N = 39, 64%). Multivariate logistic regression analysis showed baseline QRSd (95% CI 1.019-1.100, P = 0.006) and pre-CRT Reduced Wall Thickening (RWT) (95% CI 1.016-1.173, P = 0.028) were independent predictors for the development of SR.

CONCLUSION

More than one third of patients showed SR after CRT who had more post-CRT improvement on LV function and dyssynchrony than those without SR. Wider QRSd and higher RWT before CRT were related to the development of SR after CRT.

An Evaluation of Phase Analysis to Interpret Atrial Activation Patterns during Persistent Atrial Fibrillation for Targeted Ablation

BACKGROUND

Phase analysis has been used to identify and localize atrial fibrillation (AF) sources for targeted ablation. We previously demonstrated that repetitive wannabe reentry (incomplete reentry) often generated an apparent stable rotor using phase analysis. The misinterpretation caused by phase analysis using atrial electrograms (AEGs) may result from detecting inaccurate time points at phase inversion (π to -π) in the instantaneous phase waveform converted from AEG. The purpose of this study was to evaluate the accuracy of phase analysis to detect atrial activations recorded from the high-density mapping of AF in patients with persistent and long-standing persistent (LSP) AF.

METHODS AND RESULTS

During open heart surgery, we recorded activation from both atria simultaneously using 512 electrodes in 7 patients with persistent and LSP AF. The phase analysis was compared to manual measurements during 4 s of data. For the accuracy of activation sequence maps, a successful recording site was defined as having ≤4 mismatched activation times during the 4 s. In all AF episodes, the accuracy of the phase analysis was only 82% of the total number of activation times due to either activation time differences (14.7%), under-sensing (2.7%), or over-sensing (0.6%). Only 67.9% of the total recording sites met the requirement of a successful recording site by phase analysis. In unsuccessful recording sites, AEG characteristics were relatively irregular cycle length (CL), complex AEG, and double potential AEG.

CONCLUSION

The phase analysis was less accurate in recording sites with a relatively irregular CL, complex AEG, or double potential AEG. As a result, phase analysis may lead to the misinterpretation of atrial activation patterns during AF. A visual review of the original AEG is needed to confirm the detected AF sources of phase analysis before performing targeted ablation.

Manufacturing of Ti-Nb-Cr-V-Ni-Al Refractory High-Entropy Alloys Using Direct Energy Deposition

High-entropy alloys (HEAs) are composed of 5-35 at% of five or more elements, have high configurational entropy, do not form intermetallic compounds, and have a single-phase face-centered cubic structure or body-centered cubic structure. In particular, refractory HEAs (RHEAs), based on refractory materials with excellent mechanical properties at high temperatures, have high strength and hardness at room temperature and excellent mechanical properties at low and high temperatures. In this study, the Ti-Nb-Cr-V-Ni-Al RHEAs were deposited using direct energy deposition (DED). In the microstructure of Ti-Nb-Cr-V-Ni-Al, the sigma, BCC A2, and Ti2Ni phases appeared to be different from the BCC A2, BCC B2, and Laves phases predicted in the phase diagram. This microstructure was similar to that of the casted Ti-Nb-Cr-V-Ni-Al and had a constructed fine grain size. It was found that the growth of these microstructures was due to the DED process, which has a fast solidification rate. The fine grain size caused high hardness, and the microhardness of the Ti-Nb-Cr-V-Ni-Al was measured to be about 900 HV. In addition, in order to analyze the thermal properties of Ti-Nb-Cr-V-Ni-Al composed of the refractory material, the heat-affected zone (HAZ) was analyzed through a preheating test. The HAZ was decreased, owing to the high thermal diffusivity of Ti-Nb-Cr-V-Ni-Al.

Unravelling the Nature of the Intrinsic Complex Structure of Binary-Phase Na-Layered Oxides

The layered sodium transition metal oxide, NaTMO₂ (TM = transition metal), with a binary or ternary phases has displayed outstanding electrochemical performance as a new class of strategy cathode materials for sodium-ion batteries (SIBs). Herein, an in-depth phase analysis of developed Na_1-x TMO₂ cathode materials, Na_0.76 Ni_0.20 Fe_0.40 Mn_0.40 O₂ with P2- and O3-type phases (NFMO-P2/O3) is offered. Structural visualization on an atomic scale is also provided and the following findings are unveiled: i) the existence of a mixed-phase intergrowth layer distribution and unequal distribution of P2 and O3 phases along two different crystal plane indices and ii) a complete reversible charge/discharge process for the initial two cycles that displays a simple phase transformation, which is unprecedented. Moreover, first-principles calculations support the evidence of the formation of a binary NFMO-P2/O3 compound, over the proposed hypothetical monophasic structures (O3, P3, O'3, and P2 phases). As a result, the synergetic effect of the simultaneous existence of P- and O-type phases with their unique structures allows an extraordinary level of capacity retention in a wide range of voltage (1.5-4.5 V). It is believed that the insightful understanding of the proposed materials can introduce new perspectives for the development of high-voltage cathode materials for SIBs.

Prognostic value of left ventricular mechanical dyssynchrony induced by exercise stress in patients with normal myocardial perfusion single-photon emission computed tomography

BACKGROUND

Left ventricular mechanical dyssynchrony (LVMD) induced by exercise stress was reported to be clinically useful in detecting multivessel coronary artery diseases. The aim of this study was to compare the prognostic value of LVMD induced by pharmacological stress with that induced by exercise stress.

METHODS

We retrospectively examined 918 consecutive patients who underwent exercise (N = 310) or pharmacological stress (N = 608) 99mTc-tetrofosmin single-photon emission computed tomography (SPECT) with normal myocardial perfusion. LVMD was evaluated by phase analysis as the indices of phase bandwidth and phase standard deviation (PSD).

RESULTS

During the follow-up period (2.2 ± 1.9 years), 74 major cardiac events (MCEs) occurred (7 cases of cardiac death, 17 cases of heart failure, and 50 cases of coronary intervention). In global patients, the indices of LVMD on rest images were significantly greater in patients with MCEs (bandwidth (°): 51 ± 31 vs 37 ± 21, P = .001, PSD: 14 ± 9 vs 10 ± 6, P = .001). The exercise stress bandwidth was significantly higher in patients with MCEs (62 ± 37° vs 42 ± 21°, P = .026), as was the pharmacological stress bandwidth (57 ± 35° vs 43 ± 24°, P = .006). Multivariate analysis demonstrated the exercise stress bandwidth to be an independent predictor of MCEs (HR 1.017, CI 1.003 to 1.032, P = .019), but the pharmacological stress bandwidth had no influence on MCEs.

CONCLUSIONS

LVMD induced by exercise stress was an independent predictor of MCEs in patients with normal perfusion SPECT, whereas that induced by pharmacological stress had no association with further events.

Ni-Cr Powders Modified with Rhenium as a Novel Coating Material-Physical Properties, Microstructure, and Behavior in Plasma Plume

The aim of this work was to develop a new coating material based on Ni20Cr alloy modified with up to 50%wt. rhenium. The modification was carried out by the mechanical mixing of the base powder and ammonium perrhenate with the subsequent thermoreduction in an H₂ atmosphere. The obtained powder consists of a nickel-chromium core surrounded by a rhenium shell. The characterization of the powders-including their microstructure, phase and chemical composition, density, flowability, particle size distribution, and specific surface area-was performed. The influence of plasma current intensity and hydrogen gas flow on in-flight particle temperature and velocity were investigated. The results indicate that there is interdiffusion between the base Ni20Cr and the rhenium shell, resulting in intermediary solid solution(s). The modified powders have a higher specific surface area and a lower flowability, but this does not prevent them from being used as feedstock in plasma spraying. In-flight measurements reveal that increasing the content of rhenium allows for the higher temperature of particles, though it also reduces their speed.

Prognostic value of ventricular mechanical dyssynchrony in patients with left ventricular aneurysm: A comparative study of medical and surgical treatment

BACKGROUND

The prognostic value of left ventricular (LV) mechanical dyssynchrony (MD) in patients with LV aneurysm (LVA) is unclear. This study aimed to investigate the long-term prognostic value of LVMD in LVA patients.

METHODS

92 consecutive patients who underwent 99mTc-sestamibi-gated SPECT myocardial perfusion imaging (GSPECT) were retrospectively analyzed and followed-up for a median of 63 months (range, 1-73 months). LV function and histogram bandwidth (BW) were analyzed by QGS software. LVMD was defined by ROC analysis. Cardiac death was defined as the primary endpoint, and the composite of cardiac deaths and severe or acute heart failure (MACE) as the secondary endpoint.

RESULTS

The annual cardiac mortality rate of LVA patients with LVMD and treated by surgical therapy was significantly lower than those treated by medical therapy (2.40% vs. 6.40%, P < .05) but not annual MACE rate (6.61% vs. 10.06%, P > .05). In patients without LVMD, no significant difference in survival and MACE-free survival between medical and surgical treatment. In addition, the occurrence of LVMD is related to the worsen cardiac outcome in terms of MACE and cardiac death, independent of the treatment methods. BW was an independent predictor for MACE (HR 1.010, P < .01) and LVEF (HR .928, P < .05) was an independent predictor for cardiac death in all LVA patients.

CONCLUSIONS

LVA patients with LVMD might be associated with high risk for cardiac death and surgical treatment might improve cardiac survival compared to medical therapy in these patients.

Optimization of Single α-Phase for Promoting Ferromagnetic Properties of 44Fe-28Cr-22Co-3Mo-1Ti-2V Permanent Magnet with Varying Co Concentration for Energy Storage

The thermal stability and structural, microstructural and magnetic properties of (40 + x) Fe–28Cr–(26 − x) Co–3Mo–1Ti–2V magnets with x = 0, 2, 4 addition in cobalt content were investigated and presented. The magnetic alloys were synthesized by vacuum arc melting and casting technique in a controlled argon atmosphere. Magnetic properties in the alloys were convinced by single-step isothermal field treatment and subsequent aging. The alloys were investigated for thermal stability, structural, microstructural and magnetic properties via differential thermal analysis (DTA), X-ray diffractometery (XRD), optical microscopy (OM), field emission scanning electron microscope (FESEM) and DC magnetometer. Metallurgical grains of size 300 ± 10 μm were produced in the specimens by casting and refined by subsequent thermal treatments. The magnetic properties of the alloys were achieved by refining the microstructure, the optimization of conventional thermomagnetic treatment to modified single-step isothermal field treatment and subsequent aging. The best magnetic properties achieved for the alloy 44Fe–28Cr–22Co–3Mo–0.9Ti–2V was coercivity H_c = 890 Oe (71 kA/m), B_r = 8.43 kG (843 mT) and maximum energy product (BH)_max = 3 MGOe (24 kJ/m³). The enhancement of remanence and coercivity enabled by the isothermal field treatment was due to the elongation of the ferromagnetic phase and step aging treatment due to the increase in the volume fraction. This work is interesting for spin-based electronics to be used for energy storage devices.

XRD and TG-DTA Study of New Phosphate-Based Geopolymers with Coal Ash or Metakaolin as Aluminosilicate Source and Mine Tailings Addition

Coal ash-based geopolymers with mine tailings addition activated with phosphate acid were synthesized for the first time at room temperature. In addition, three types of aluminosilicate sources were used as single raw materials or in a 1/1 wt. ratio to obtain five types of geopolymers activated with H3PO4. The thermal behaviour of the obtained geopolymers was studied between room temperature and 600 °C by Thermogravimetry-Differential Thermal Analysis (TG-DTA) and the phase composition after 28 days of curing at room temperature was analysed by X-ray diffraction (XRD). During heating, the acid-activated geopolymers exhibited similar behaviour to alkali-activated geopolymers. All of the samples showed endothermic peaks up to 300 °C due to water evaporation, while the samples with mine tailings showed two significant exothermic peaks above 400 °C due to oxidation reactions. The phase analysis confirmed the dissolution of the aluminosilicate sources in the presence of H3PO4 by significant changes in the XRD patterns of the raw materials and by the broadening of the peaks because of typically amorphous silicophosphate (Si-P), aluminophosphate (Al-P) or silico-alumino-phosphate (Si-Al-P) formation. The phases resulted from geopolymerisation are berlinite (AlPO4), brushite (CaHPO4∙2H2O), anhydrite (CaSO4) or ettringite as AFt and AFm phases.

Fatigue Damage Evaluation of Short Carbon Fiber Reinforced Plastics Based on Thermoelastic Temperature Change and Second Harmonic Components of Thermal Signal

Short fiber reinforced plastics (SFRPs) have excellent moldability and productivity compared to continuous fiber composites. In this study, thermoelastic stress analysis (TSA) was applied to detect delamination defects in short carbon fiber reinforced plastics (SCFRPs). The thermoelastic temperature change ΔT_E, phase of thermal signal θ_E, and second harmonic temperature component ΔT_D were measured. In the fatigue test of SCFRP, it was confirmed that changes in ΔT_E, θ_E, and ΔT_D appeared in the damaged regions. A staircase-like stress level test for a SCFRP specimen was conducted to investigate the generation mechanism of the ΔT_D. The distortion of the temperature change appeared at the maximum tension stress of the sinusoidal load—and when the stress level decreased, the temperature change returned to the original sinusoidal waveform. ΔT_D changed according to the change in the maximum stress during the staircase-like stress level test, and a large value of ΔT_D was observed in the final ruptured region. A distortion of the temperature change and ΔT_D was considered to be caused by the change in stress sharing condition between the fiber and resin due to delamination damage. Therefore, ΔT_D can be applied to the detection of delamination defects and the evaluation of damage propagation.

Effect of Sintering Factors on Properties of Al-Rich PTFE/Al/TiH2 Active Materials

Sintering process is an important part of the specimen preparation process, which directly affects the properties of materials. In order to obtain the best sintering control factors of Al-rich PTFE/Al/TiH₂ active materials, Al-rich PTFE/Al/TiH₂ active specimens with different sintering control factors were prepared using a mold pressing sintering method. A quasi-static compression experiment was carried out on a universal material testing machine, and a real stress-strain curve was obtained. The effects of sintering control factors on the properties of Al-rich PTFE/Al/TiH₂ active materials were analyzed by means of mechanical parameters such as compressive strength, failure strain and toughness. SEM and XRD were used to analyze the microstructure and phase of the sintered samples. The results show that: (1) With the increase of cooling rate, the density, yield strength, strain hardening modulus, compressive strength and toughness of Al-rich Al/PTFE/TiH₂ specimens decrease gradually, while the failure strain and pores of the specimens increase gradually. (2) With the increase of sintering temperature, the density, maximum true strain and toughness of the specimens first increase and then decrease, and the failure strain of the specimens gradually increases. When the sintering temperature is 360 °C, the PTFE matrix and particles inside the specimen are closely combined, a small number of particles are exposed on the PTFE matrix and there are a small number of voids. (3) With the increase of holding time at 360 °C, the strength and toughness of the material first decrease and then increase. When the holding time is 6 h, the interface between particles and matrix inside the specimen is the strongest, and the crack propagation inside the specimen is less. (4) When the sintering time increased from 1 h to 4 h at 315 °C, the compressive strength of the specimen increased by 1.62%, the toughness of the specimen decreased by 0.55% and the failure strain of the specimen decreased by 0.54%. The interface between PTFE matrix and particles is the strongest and the crack propagation is less in the specimen with a holding time of 4 h. (5) Above all, the optimum sintering parameters of Al-rich Al/PTFE/TiH₂ materials are cooling rate of 25 °C/h, sintering temperature of 360 °C, holding time of 6 h and holding time of 4 h at 315 °C. (6) The reactivity of Al-rich Al/PTFE/TiH₂ specimens with 10% content of TiH₂ under static compression is not significantly affected by sintering parameters.

Influence of Molding Parameters on Quasi-Static Mechanical Properties of Al-Rich Al/PTFE/TiH2 Active Materials

Preforming pressure and the pressure holding time are important parameters of the molding process, which directly affect the mechanical properties of materials. In order to obtain the best molding parameters of Al-rich Al/PTFE/TiH₂ composites, based on the quasi-static compression test, the influence of molding parameters on the mechanical properties of Al-rich Al/PTFE/TiH₂ composites was analyzed, and the microstructure characteristics of Al-rich Al/PTFE/TiH₂ specimens were analyzed by SEM. An X-ray diffractometer was used to analyze the phase of the residue after quasi-static compression experiment. The results show that: (1) With the increase in molding parameters (preforming pressure and the pressure holding time), the compressive strength, failure strain and toughness of Al-rich Al/PTFE/TiH₂ specimens first increase and then decrease. The best molding process parameters of Al-rich Al/PTFE/TiH₂ materials are preforming pressure 240 MPa and the pressure holding time 100 s. (2) For unsintering specimens, when the preforming pressure is less than 150 MPa, the porosity of the specimen increases slowly at first and then decreases. When the preforming pressure is greater than 150 MPa, the porosity of the specimen increases first and then decreases. When the pressure holding time is no more than 100 s, the porosity of the specimen decreases gradually. When the pressure holding time is more than 100 s, the porosity of the specimen increases first and then decreases. For sintered specimens, when the preforming pressure is less than 100 MPa, the porosity of the specimen decreases gradually. When the preforming pressure is greater than 100 MPa, the porosity of the specimen first increases and then decreases. With the increase in the pressure holding time, the porosity first increases and then decreases. For each preforming pressure specimen, compared with that before sintering, the porosity after sintering either decreases or increases. For each the pressure holding time specimen, the porosity increases after sintering compared with that before sintering. The microstructure of PTFE crystal inside the specimen is mainly planar PTFE crystal. The size and number of planar PTFE crystals are significantly affected by the molding parameters, which further affects the mechanical properties of Al-rich Al/PTFE/TiH₂ specimens. When the preforming pressure is less than 100 MPa, the planar PTFE crystals are small and few, which results in the worst mechanical properties of the specimens. When the preforming pressure is more than 100 MPa and does not contain 240 Mpa, the planar PTFE crystals are small and there are more of them, which results in better mechanical properties of the specimens. When the preforming pressure is 240 MPa, the planar PTFE crystals are large and numerous, which results in the best mechanical properties of the specimen. When the pressure holding time is 100 s, the planar PTFE crystals are large and there are more of them, which results in the best mechanical properties of the specimen. (3) The reactivity of Al-rich Al/PTFE/TiH₂ specimens with TiH₂ the content of 10% under quasi-static compression is not significantly affected by the molding parameters.

Influence of Sintering Temperature of Kaolin, Slag, and Fly Ash Geopolymers on the Microstructure, Phase Analysis, and Electrical Conductivity

This paper clarified the microstructural element distribution and electrical conductivity changes of kaolin, fly ash, and slag geopolymer at 900 °C. The surface microstructure analysis showed the development in surface densification within the geopolymer when in contact with sintering temperature. It was found that the electrical conductivity was majorly influenced by the existence of the crystalline phase within the geopolymer sample. The highest electrical conductivity (8.3 × 10^-4 Ωm^-1) was delivered by slag geopolymer due to the crystalline mineral of gehlenite (3Ca₂Al₂SiO₇). Using synchrotron radiation X-ray fluorescence, the high concentration Ca boundaries revealed the appearance of gehlenite crystallisation, which was believed to contribute to development of denser microstructure and electrical conductivity.

Targeted Double-Stranded cDNA Sequencing-Based Phase Analysis to Identify Compound Heterozygous Mutations and Differential Allelic Expression

Simple Summary

Phase analysis to distinguish between in cis and in trans heterozygous mutations is important for clinical diagnosis because in trans compound heterozygous mutations cause autosomal recessive diseases. However, conventional phase analysis is limited because of the large target size of genomic DNA. Here, we performed a targeted double-stranded cDNA sequencing-based phase analysis to resolve the limitation of distance using direct adapter ligation library preparation and paired-end sequencing; we elucidated that two heterozygous mutations on a patient with Wilson disease are in trans compound heterozygous mutations. Furthermore, we detected the differential allelic expression. Our results indicate that a targeted double-stranded cDNA sequencing-based phase analysis is useful for determining compound heterozygous mutations and confers information on allelic expression.

Abstract

There are two combinations of heterozygous mutation, i.e., in trans, which carries mutations on different alleles, and in cis, which carries mutations on the same allele. Because only in trans compound heterozygous mutations have been implicated in autosomal recessive diseases, it is important to distinguish them for clinical diagnosis. However, conventional phase analysis is limited because of the large target size of genomic DNA. Here, we performed a genetic analysis on a patient with Wilson disease, and we detected two heterozygous mutations chr13:51958362;G>GG (NM_000053.4:c.2304dup r.2304dup p.Met769HisfsTer26) and chr13:51964900;C>T (NM_000053.4:c.1841G>A r.1841g>a p.Gly614Asp) in the causative gene ATP7B. The distance between the two mutations was 6.5 kb in genomic DNA but 464 bp in mRNA. Targeted double-stranded cDNA sequencing-based phase analysis was performed using direct adapter ligation library preparation and paired-end sequencing, and we elucidated they are in trans compound heterozygous mutations. Trio analysis showed that the mutation (chr13:51964900;C>T) derived from the father and the other mutation from the mother, validating that the mutations are in trans composition. Furthermore, targeted double-stranded cDNA sequencing-based phase analysis detected the differential allelic expression, suggesting that the mutation (chr13:51958362;G>GG) caused downregulation of expression by nonsense-mediated mRNA decay. Our results indicate that targeted double-stranded cDNA sequencing-based phase analysis is useful for determining compound heterozygous mutations and confers information on allelic expression.

Quantitative clinical nuclear cardiology, part 2: Evolving/emerging applications

Quantitative analysis has been applied extensively to image processing and interpretation in nuclear cardiology to improve disease diagnosis and risk stratification. This is Part 2 of a two-part continuing medical education article, which will review the potential clinical role for emerging quantitative analysis tools. The article will describe advanced methods for quantifying dyssynchrony, ventricular function and perfusion, and hybrid imaging analysis. This article discusses evolving methods to measure myocardial blood flow with positron emission tomography and single-photon emission computed tomography. Novel quantitative assessments of myocardial viability, microcalcification and in patients with cardiac sarcoidosis and cardiac amyloidosis will also be described. Lastly, we will review the potential role for artificial intelligence to improve image analysis, disease diagnosis, and risk prediction. The potential clinical role for all these novel techniques will be highlighted as well as methods to optimize their implementation.

Value of intraventricular dyssynchrony assessment by gated-SPECT myocardial perfusion imaging in the management of heart failure patients undergoing cardiac resynchronization therapy (VISION-CRT)

BACKGROUND

Placing the left ventricular (LV) lead in a viable segment with the latest mechanical activation (vSOLA) may be associated with optimal cardiac resynchronization therapy (CRT) response. We assessed the role of gated SPECT myocardial perfusion imaging (gSPECT MPI) in predicting clinical outcomes at 6 months in patients submitted to CRT.

METHODS

Ten centers from 8 countries enrolled 195 consecutive patients. All underwent gSPECT MPI before and 6 months after CRT. The procedure was performed as per current guidelines, the operators being unaware of gSPECT MPI results. Regional LV dyssynchrony (Phase SD) and vSOLA were automatically determined using a 17 segment model. The lead was considered on-target if placed in vSOLA. The primary outcome was improvement in ≥1 of the following: ≥1 NYHA class, left ventricular ejection fraction (LVEF) by ≥5%, reduction in end-systolic volume by ≥15%, and ≥5 points in Minnesota Living With Heart Failure Questionnaire (MLHFQ).

RESULTS

Sixteen patients died before the follow-up gSPECT MPI. The primary outcome occurred in 152 out of 179 (84.9%) cases. Mean change in LV phase standard deviation (PSD) at 6 months was 10.5°. Baseline dyssynchrony was not associated with the primary outcome. However, change in LV PSD from baseline was associated with the primary outcome (OR 1.04, 95% CI 1.01-1.07, P = .007). Change in LV PSD had an AUC of 0.78 (0.66-0.90) for the primary outcome. Improvement in LV PSD of 4° resulted in the highest positive likelihood ratio of 7.4 for a favorable outcome. In 23% of the patients, the CRT lead was placed in the vSOLA, and in 42% in either this segment or in a segment within 10° of it. On-target lead placement was not significantly associated with the primary outcome (OR 1.53, 95% CI 0.71-3.28).

CONCLUSION

LV dyssynchrony improvement by gSPECT MPI, but not on-target lead placement, predicts clinical outcomes in patients undergoing CRT.

Prognostic value of left ventricular mechanical dyssynchrony in hypertrophic cardiomyopathy patients with low risk of sudden cardiac death

PURPOSES

This study aims to explore the prognostic value of left ventricular mechanical dyssynchrony (LVMD) in hypertrophic cardiomyopathy (HCM) patients with low risk of sudden cardiac death (SCD).

METHODS

This retrospective study was performed in 50 patients with HCM who underwent Tc-99m sestamibi GSPECT-MPI. All patients were at low risk of SCD, defined as HCM risk-SCD scores <6%. Phase SD (PSD) and phase histogram bandwidth (PBW) were measured for assessment of LVMD. The primary endpoint was the composite major adverse cardiovascular events (MACE), including all-cause mortality, rehospitalization of heart failure symptoms, new-onset stroke, and new-onset syncope. Variables with significant difference between MACE group and non-MACE group were further assessed by Cox regression analysis.

RESULTS

During follow-up, MACE occurred in 20 patients. Systolic-PSD, systolic-PBW, diastolic-PSD, and diastolic-PBW were all significantly greater in the MACE group. Multivariate analysis revealed that history of syncope, history of atrial fibrillation, and all the four LVMD parameters were independent predictors of MACE. All LVMD parameters showed similar accuracy to predict MACE. Sequential models indicated that both systolic and diastolic LVMD parameters added incremental value beyond atrial fibrillation and syncope.

CONCLUSION

LVMD parameters are independent predictors of MACE, which add incremental prognostic information in patients with HCM risk-SCD scores <6%.

X-ray and Thermal Analysis of Selected Drugs Containing Acetaminophen

Studies carried out by X-ray and thermal analysis confirmed that acetaminophen (paracetamol), declared by the manufacturers as an Active Pharmaceutical Ingredient (API), was present in all studied medicinal drugs. Positions of diffraction lines (2θ angles) of the studied drugs were consistent with standards for acetaminophen, available in the ICDD PDF database Release 2008. |Δ2θ| values were lower than 0.2°, confirming the authenticity of the studied drugs. Also, the values of interplanar distances d_hkl for the examined samples were consistent with those present in the ICDD. Presence of acetaminophen crystalising in the monoclinic system (form I) was confirmed. Various line intensities for API were observed in the obtained diffraction patterns, indicating presence of the preferred orientation of the crystallites in the examined samples. Thermal analysis of the studied substances confirmed the results obtained by X-ray analysis. Drugs containing only acetaminophen as an API have melting point close to that of pure acetaminophen. It was found that presence of other active and auxiliary substances affected the shapes and positions of endothermal peaks significantly. A broadening of endothermal peaks and their shift towards lower temperatures were observed accompanying an increase in the contents of additional substances being “impurities” in relation to the API. The results obtained by a combination of the two methods, X-ray powder diffraction (XRPD) and differential scanning calorimetry/thermogravimetry (DSC/TGA), may be useful in determination of abnormalities which can occur in pharmaceutical preparations, e.g., for distinguishing original drugs and forged products, detection of the presence of a proper polymorphic form or too low content of the active substance in the investigated drug.

Left ventricular dyssynchrony and abnormalities in wall motion, assessed by gated-SPECT as ischemic auxiliary markers

INTRODUCTION

Left ventricular dyssynchrony (LVD) quantified by gated myocardial perfusion studies (MPS), through phase analysis (PA), has shown controversial results in myocardial stunning.

OBJECTIVES

Assessment of LVD and regional wall motion abnormalities (RWMA) in normal and ischemic patients.

METHODS

A cohort of 172 patients were studied. Summed Stress Score (SSS), Summed Resting Score (SRS), and Summed Difference Score (SDS) were evaluated. Group 1-patients with normal MPS (N = 133) and Group 2-patients with myocardial ischemia in the MPS (N = 39). LVD was evaluated through PA and RWM by visual analysis.

RESULTS

SSS 0 vs 9.8 ± 3.9 P = .0001; SDS 0 vs 9.8 ± 3.9 P = .0001; SRS 0 vs 0 P = NS, in G1 and G2. Significant differences were found in LVD between G1 and G2, bandwidth 36 ± 14 vs 63 ± 46 P = .0001; standard deviation 16 ± 10 vs 26 ± 15 P = .0001. In G1, 16% had LVD vs RWMA in 0%, P = .0001 and in G2, 59% with LVD vs 33% with RWMA, P = .03. Sensitivity for LVD 59% and for RWMA 33%, P = .03 and specificity for LVD 83% and for RWMA 100%, P = .0001.

CONCLUSION

Ischemic patients have LVD post-stress due to myocardial stunning. LVD measured by PA could be a useful tool to identify ischemia.

Laser Surface Alloying of Austenitic 316L Steel with Boron and Some Metallic Elements: Microstructure

Austenitic 316L steel is known for its good oxidation resistance and corrosion behavior. However, the poor wear protection is its substantial disadvantage. In this study, laser surface alloying with boron and some metallic elements was used in order to form the surface layers of improved wear behavior. The microstructure was studied using OM, SEM, XRD, and EDS techniques. The laser-alloyed layers consisted of the only re-melted zone (MZ). The hard ceramic phases (Fe₂B, Cr₂B, Ni₂B, or Ni₃B borides) occurred in a soft austenitic matrix. The relatively high overlapping (86%) resulted in a uniform thickness and homogeneous microstructure of the layers. All the laser-alloyed layers were free from defects, such as microcracks or gas pores, due to the use of relatively high dilution ratios (above 0.37). The heat-affected zone (HAZ) wasn’t visible in the microstructure because of the extended stability of austenite up to room temperature and no possibility to change this structure during fast cooling. The use of the mixtures of boron and selected metallic elements as the alloying materials caused the diminished laser beam power in order to obtain the layers of acceptable quality. The thickness of laser-alloyed layers (308–432 μm) was significantly higher than that produced using diffusion boriding techniques.

Quantitative clinical nuclear cardiology, part 2: Evolving/emerging applications

Quantitative analysis has been applied extensively to image processing and interpretation in nuclear cardiology to improve disease diagnosis and risk stratification. This is Part 2 of a two-part continuing medical education article, which will review the potential clinical role for emerging quantitative analysis tools. The article will describe advanced methods for quantifying dyssynchrony, ventricular function and perfusion, and hybrid imaging analysis. This article discusses evolving methods to measure myocardial blood flow with positron emission tomography and single-photon emission computed tomography. Novel quantitative assessments of myocardial viability, microcalcification and in patients with cardiac sarcoidosis and cardiac amyloidosis will also be described. Lastly, we will review the potential role for artificial intelligence to improve image analysis, disease diagnosis, and risk prediction. The potential clinical role for all these novel techniques will be highlighted as well as methods to optimize their implementation. (J Nucl Cardiol 2020).

Prognostic value of left ventricular mechanical dyssynchrony indices in long-standing type II diabetes mellitus with normal perfusion and left ventricular systolic functions on SPECT-MPI

OBJECTIVE

To test whether phase analysis indices from SPECT-MPI for left ventricular mechanical dyssynchrony (LVMD) are predictors of major adverse cardiac events (MACEs) in long-standing diabetes mellitus (DM).

METHODS

A total of 136 DM patients with normal perfusion and left ventricular systolic functions were followed up for about two years and divided into two groups according to the presence and the absence of MACEs.

RESULT

Thirteen (9.5%) patients experienced MACEs during follow-up. Patients experiencing MACEs showed significantly higher phase standard deviation (PSD) and wider phase bandwidth (PBW) than those who did not. Moreover, both PSD and PBW showed significant correlations (r = 0.25 and 0.27; P < 0.05) with duration of DM. Logistic regression analysis revealed significant associations of DM duration, microvascular complications, and LVMD indices for predicting MACEs. Kaplan-Meier event-free survival analysis revealed significantly higher rate of MACEs (Logrank = 10.02; P = 0.001) in patients with high PSD and wide PBW. An overall fit model consisting of high-PSD and wide-PBW group was improved with the addition of microvascular complications (χ2 = 15.9; P = 0.03) and further by addition of DM duration of ≥ 15 years (χ2 = 24.3; P = 0.007) as variables.

CONCLUSION

LVMD indices are novel prognostic markers in diabetic patients with normal perfusion and left ventricular systolic functions and their increases in magnitudes with DM-duration and in the presence of microvascular complications.

Spectral deconvolution in electrophoretic NMR to investigate the migration of neutral molecules in electrolytes

Electrophoretic nuclear magnetic resonance (eNMR) is a powerful tool in studies of nonaqueous electrolytes, such as ionic liquids. It delivers electrophoretic mobilities of the ionic constituents and thus sheds light on ion correlations. In applications of liquid electrolytes, uncharged additives are often employed, detectable via ¹ H NMR. Characterizing their mobility and coordination to charged entities is desirable; however, it is often hampered by small intensities and ¹ H signals overlapping with major constituents of the electrolyte. In this work, we evaluate methods of phase analysis of overlapping resonances to yield electrophoretic mobilities even for minor constituents. We use phase-sensitive spectral deconvolution via a set of Lorentz distributions for the investigation of the migration behavior of additives in two different ionic liquid-based lithium salt electrolytes. For vinylene carbonate as an additive, no field-induced drift is observed; thus, its coordination to the Li⁺ ion does not induce a correlated drift with Li⁺ . On the other hand, in a solvate ionic liquid with tetraglyme (G4) as an additive, a correlated migration of tetraglyme with lithium as a complex solvate cation is directly proven by eNMR. The phase evaluation procedure of superimposed resonances thus broadens the applicability of eNMR to application-relevant complex electrolyte mixtures containing neutral additives with superimposed resonances.

Reducing Supervision of Quantitative Image Analysis of Meteorite Samples

When selecting a method for determining modal mineralogy and elemental composition of geological samples (e.g., meteorites), a number of factors should be considered, includingthe number of objects or the area to be analyzed; the scale of expected chemical variation; instrument time restrictions; and post-processing time. This study presents a method that minimizes acquisition time while maintaining the ability to distinguish minerals based on combinations of intensities of electron probe micro-analyzer-generated X-ray element maps. While some other methods yield similar outcomes, this method's post-processing utilizes standard parameterized, X-ray intensity "map math" in an algorithm that is adaptable and requires minimal supervision once implemented. This study's minimized supervision in the post-processing of X-ray intensity maps decreases analysis time and its adaptability increases the number of potential applications. The method also facilitates calibration of the exact locations of analysis using laser ablation methods. While the method described here has advantages, the choice of method always depends on the question being asked.

The clinical usefulness of phase analysis in detecting coronary artery disease using dipyridamole thallium-201-gated myocardial perfusion imaging with a cadmium-zinc-telluride camera

BACKGROUND

Previous studies have demonstrated left ventricular mechanical dyssynchrony (LVMD) in patients with severe coronary artery disease (CAD) with ≥ 70% stenosis. The aim of this study was to evaluate the clinical usefulness of stress/rest LVMD in the diagnosis of CAD with ≥ 50% stenosis using dipyridamole thallium-201 (Tl-201) myocardial perfusion imaging (MPI) with a cadmium-zinc-telluride camera.

METHODS AND RESULTS

A total of 476 patients without known CAD who underwent dipyridamole Tl-201 MPI and coronary angiography within 6 months were retrospectively reviewed. LVMD parameters including phase standard deviation and phase histogram bandwidth, phase skewness and phase kurtosis, as well as myocardial perfusion and myocardial stunning were assessed in post-stress and rest MPI. Relationships between the presence of CAD on coronary angiography and single photon emission computerized tomography (SPECT) parameters were evaluated. The presence of perfusion abnormalities was the best diagnostic tool in detecting CAD. Although less left ventricular synchrony was observed post-stress in the CAD group compared to the non-CAD group, no significant dyssynchrony was noted.

CONCLUSIONS

The addition of phase analysis to help diagnose CAD in Tl-201-gated SPECT with dipyridamole stress may have limited value in patients with CAD with ≥ 50% stenosis.

Phase analysis of gated PET in the evaluation of mechanical ventricular synchrony: A narrative overview

Noninvasive imaging modalities offer the possibility to dynamically evaluate cardiac motion during the cardiac cycle by means of ECG-gated acquisitions. Such motion characterization along with orientation, segmentation preprocessing, and ultimately, phase analysis, can provide quantitative estimates of ventricular mechanical synchrony. Current evidence on the role of mechanical synchrony evaluation is mainly available for echocardiography and gated single-photon emission computed tomography, but less is known about the utilization of gated positron emission tomography (PET). Although data available are sparse, there is indication that mechanical synchrony evaluation can be of diagnostic and prognostic values in patients with known or suspected coronary artery disease-related myocardial ischemia, prediction of response to cardiac resynchronization therapy, and estimation of risk for adverse cardiac events in patients' heart failure. As such, the evaluation of mechanical ventricular synchrony through phase analysis of gated acquisitions represents a value addition to modern cardiac PET imaging modality, which warrants further research and development in the evaluation of patients with cardiovascular disease.

Left ventricular mechanical dyssynchrony assessment in long-standing type II diabetes mellitus patients with normal gated SPECT-MPI

BACKGROUND

Assessment of left ventricular mechanical dyssynchrony (LVMD) using phase analysis of gated SPECT-MPI is well established. However, there is little information about the influence of diabetes mellitus on phase analysis. The present work was to evaluate the LVMD in longstanding type II diabetes mellitus (DM) patients with normal gated SPECT-MPI.

METHODS

Retrospective analysis of 146 (86 type II diabetics for > 5 years' duration and 60 nondiabetics) consecutive patients with normal gated SPECT-MPI and adequate LVEF was done. Sixty age- and sex-matched nondiabetic served as control. LVMD was determined from the cutoff values (> mean + 2 SD) observed for phase standard deviation (PSD) and phase bandwidth (PBW) from the control subjects. Multivariate logistic regression analysis was applied to assess the correlation between various confounding factors.

RESULTS

LVMD was detected in 24 (28%) diabetic patients with the pre-defined cut-off values for PSD (> 10.8) and PBW (> 35.6) derived from the controls. Hyperlipidemia, overweight/obesity, duration of DM and its long-term complications were independently associated with LVMD, with long-term complications being the highest risk factor (OR 28.00; P < .001).

CONCLUSION

The evolution time of the patients with type II diabetes mellitus affects the left ventricular mechanical synchrony.

Behind Traditional Semi-quantitative Scores of Myocardial Perfusion Imaging: An Eye on Niche Parameters

The evaluation of stress-induced myocardial perfusion defects by non-invasive myocardial perfusion imaging (MPI) modalities has a leading role in the identification of coronary artery disease, and has excellent diagnostic and prognostic value. Non-invasive MPI can be performed using conventional and novel gamma cameras or by PET/CT. New software has allowed novel parameters that may have a role in the identification of early marks of cardiac impairment to be evaluated. We aim to give an overview of niche parameters obtainable by single photon emission CT (SPECT) and PET/CT MPI that may help practitioners to detect initial signs of cardiac damage and identify new therapy targets. In particular, we summarise the role of left ventricular geometry indices for remodelling, phase analysis parameters to evaluate mechanical dyssynchrony, the concept of relative flow reserve in the evaluation of flow-limiting epicardial stenosis, vascular age and epicardial adipose tissue as early markers of atherosclerotic burden, and emerging parameters for the evaluation of myocardial innervation, such as the total defect score.

Interactions between myocardial sympathetic denervation and left ventricular mechanical dyssynchrony: A CZT analysis

BACKGROUND

A correlation between left ventricular (LV) dyssynchrony (LVD) and impaired myocardial sympathetic tone has been hypothesized. We sought to assess the interactions between regional LV sympathetic innervation, perfusion, and mechanical dyssynchrony.

METHODS

Eighty-three patients underwent evaluation of LV perfusion and sympathetic innervation on 99mTc-tetrofosmin/123I-metaiodobenzylguanidine (123I-MIBG) imaging. The summed rest score and summed 123I-MIBG score (SS-MIBG) were computed. The extent of "innervation/perfusion" mismatch was defined as the number of denervated LV segments with relatively preserved perfusion. LVD was evaluated on phase analysis and the wall with latest mechanical activation identified.

RESULTS

LVD was revealed in 36 (43%) patients. Patients with LVD had more abnormal values of SRS (21 ± 9 vs 10 ± 8, P < 0.001) and SS-MIBG (29 ± 9 vs 17 ± 11, P < 0.001) than those without LVD. The presence of LVD also clustered with a higher burden of "innervation/perfusion" mismatch (P = 0.019). On per-wall analysis, LV walls with delayed mechanical activation showed a higher burden of "innervation/perfusion" mismatch (2.3 ± 1.4 segments) than normally contracting walls (1.3 ± 1.2 segments; P < 0.001). On multivariate analysis, the extent of "innervation/perfusion" mismatch was the only predictor of delayed mechanical activation (P = 0.029).

CONCLUSIONS

Patients with LVD show an elevated burden of "innervation/perfusion" mismatch that is concentrated at the level of the most dyssynchronous walls.

Development and validation of a new method to diagnose apical hypertrophic cardiomyopathy by gated single-photon emission computed tomography myocardial perfusion imaging

AIM

The aim of this study is to develop and validate a new method to diagnose apical hypertrophic cardiomyopathy (AHCM) by the integral quantitative analysis of myocardial perfusion and wall thickening from gated single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI).

PATIENTS AND METHODS

Twenty-two consecutive patients, who showed T wave inversion of at least 3 mm in precordial leads and sinus rhythm in ECG, were enrolled. All the patients underwent cardiac magnetic resonance (CMR), gated rest SPECT MPI and echocardiography. According to CMR diagnostic results, 13 patients were categorized as in the AHCM group and the remaining nine patients were categorized as in the non-AHCM group. Operators who were blinded to the CMR diagnosis independently performed the diagnosis by gated SPECT MPI. The regions of interest inside the apical hotspots on the perfusion polar map were drawn and the mean values of wall thickening in the drawn region of interests were calculated. Using MRI diagnosis as the gold standard, AHCM was diagnosed based on receiver operating characteristic analysis of the mean wall thickening in the apical perfusion hotspot. The area under curve, sensitivity, specificity, and accuracy of our method were 0.97, 100%, 89%, and 95%, respectively.

CONCLUSION

Our new method has high sensitivity, specificity, and accuracy against CMR diagnosis. It has great promise to become a clinical tool in the diagnosis of AHCM.

Prognostic value of left ventricular dyssynchrony evaluated by gated myocardial perfusion imaging in patients with chronic kidney disease and normal perfusion defect scores

BACKGROUND

This study aimed to investigate whether indices of left ventricular (LV) dyssynchrony by gated myocardial perfusion SPECT (GMPS) could be useful to predict prognosis in chronic kidney disease (CKD) patients with normal perfusion defect scores.

METHODS

One hundred and sixty-seven CKD patients with normal perfusion defect scores on adenosine-stress 201Tl GMPS and no previous history of overt heart diseases were enrolled. Phase standard deviation (PSD) and bandwidth (BW) were automatically calculated from GMPS. The major adverse cardiac events (MACEs) for a mean of 560 days were defined as sudden cardiac death, fatal arrhythmias, and acute coronary syndrome requiring urgent coronary revascularization. Patients were divided into two groups according to the presence or absence of MACEs.

RESULTS

The MACEs occurred in 12 patients (7.1%). Patients who experienced MACEs showed significantly higher PSD and wider BW than those who did not. In the Kaplan-Meier event-free survival analysis, cardiac event rate was significantly higher in the high-PSD and wide-BW group (n = 81) than in the low-PSD and narrow-BW group (n = 71) (P = .002). The multivariate regression analysis revealed that the PSD was associated with MACEs (odds ratio 1.33, 95% confidence interval 1.05-1.69, P = .01).

CONCLUSION

The LV dyssynchrony indices from GMPS may be novel prognostic predictors in CKD patients with normal perfusion defect scores.

Serial electron crystallography for structure determination and phase analysis of nanocrystalline materials

Serial electron crystallography has been developed as a fully automated method to collect diffraction data on polycrystalline materials using a transmission electron microscope. This enables useful data to be collected on materials that are sensitive to the electron beam and thus difficult to measure using the conventional methods that require long exposure of the same crystal. The data collection strategy combines goniometer translation with electron beam shift, which allows the entire sample stage to be probed. At each position of the goniometer, the locations of the crystals are identified using image recognition techniques. Diffraction data are then collected on each crystal using a quasi-parallel focused beam with a predefined size (usually 300-500 nm). It is shown that with a fast and sensitive Timepix hybrid pixel area detector it is possible to collect diffraction data of up to 3500 crystals per hour. These data can be indexed using a brute-force forward-projection algorithm. Results from several test samples show that 100-200 frames are enough for structure determination using direct methods or dual-space methods. The large number of crystals examined enables quantitative phase analysis and automatic screening of materials for known and unknown phases.

Interlaminar Shear Behavior of Laminated Carbon Fiber Reinforced Plastic from Microscale Strain Distributions Measured by Sampling Moiré Technique

In this article, the interlaminar shear behavior of a [±45°]_4s laminated carbon fiber reinforced plastic (CFRP) specimen is investigated, by utilizing microscale strain mapping in a wide field of view. A three-point bending device is developed under a laser scanning microscope, and the full-field strain distributions, including normal, shear and principal strains on the cross section of CFRP, in a three-point bending test, are measured using a developed sampling Moiré technique. The microscale shear strain concentrations at interfaces between each two adjacent layers were successfully detected and found to be positive-negative alternately distributed before damage occurrence. The 45° layers slipped to the right relative to the −45° layers, visualized from the revised Moiré phases, and shear strain distributions of the angle-ply CFRP under different loads. The absolute values of the shear strain at interfaces gradually rose with the increase of the bending load, and the sudden decrease of the shear strain peak value implied the occurrence of interlaminar damage. The evolution of the shear strain concentrations is useful in the quantitative evaluation of the potential interlaminar shear failure.

Mechanical dyssynchrony according to validated cut-off values using gated SPECT myocardial perfusion imaging

BACKGROUND

The aim of this study was to establish different degrees of mechanical dyssynchrony according to validated cut-off (CO) values of myocardial perfusion gated SPECT phase analysis parameters (SD, standard deviation; B, bandwidth; S, skewness; K, kurtosis).

METHODS

Using Emory Cardiac Toolbox™, we prospectively analyzed 408 patients (mean age 64.1 years, 26.7% female), divided into a control group of 150 normal subjects and a validation group of 258 patients (left bundle branch block: 17.8%, right bundle branch block: 8.9%. atrial fibrillation: 16.3%, coronary revascularization: 30%, dilated cardiomyopathy: 7.4%. valvulopathies: 2.7%, ischemic test: 45.3%) with ischemic and non-ischemic cardiac diseases, by means of phase analysis.

RESULTS

Agreement of CO values (SD > 18.4°; B > 51°; S ≤ 3.2; K ≤ 9.3) used to discriminate between normal subjects and patients was strong (c-statistic 0.9; 95% CI 0.98-0.99). Four degrees of dyssynchrony were found according to the number of abnormal phase parameters. All patients with mechanical and electrical criteria for cardiac resynchronization therapy (CCRT) (n: 82) had Grade 2 to 4 (two to four abnormal phase parameters). Agreement of CO values (SD > 40.2°; B > 132°; S ≤ 2.3; K ≤ 4.6) used to discriminate between patients with and without CCRT was strong (c-statistic 0.8; 95% CI 0.79-0.87) but 12% of patients with CCRT did not have any of these abnormal phase parameters.

CONCLUSIONS

The discriminatory capacity of gated SPECT phase analysis parameters between normal subjects and patients, and between patients with and without CCRT, is very good, making it possible to define different degrees of mechanical dyssynchrony.

Tau-independent Phase Analysis: A Novel Method for Accurately Determining Phase Shifts

Estimations of period and phase are essential in circadian biology. While many techniques exist for estimating period, comparatively few methods are available for estimating phase. Current approaches to analyzing phase often vary between studies and are sensitive to coincident changes in period and the stage of the circadian cycle at which the stimulus occurs. Here we propose a new technique, tau-independent phase analysis (TIPA), for quantifying phase shifts in multiple types of circadian time-course data. Through comprehensive simulations, we show that TIPA is both more accurate and more precise than the standard actogram approach. TIPA is computationally simple and therefore will enable accurate and reproducible quantification of phase shifts across multiple subfields of chronobiology.

Fatigue Damage Evaluation of Short Carbon Fiber Reinforced Plastics Based on Phase Information of Thermoelastic Temperature Change

Carbon fiber-reinforced plastic (CFRP) is widely used for structural members of transportation vehicles such as automobile, aircraft, or spacecraft, utilizing its excellent specific strength and specific rigidity in contrast with the metal. Short carbon fiber composite materials are receiving a lot of attentions because of their excellent moldability and productivity, however they show complicated behaviors in fatigue fracture due to the random fibers orientation. In this study, thermoelastic stress analysis (TSA) using an infrared thermography was applied to evaluate fatigue damage in short carbon fiber composites. The distribution of the thermoelastic temperature change was measured during the fatigue test, as well as the phase difference between the thermoelastic temperature change and applied loading signal. Evolution of fatigue damage was detected from the distribution of thermoelastic temperature change according to the thermoelastic damage analysis (TDA) procedure. It was also found that fatigue damage evolution was more clearly detected than before by the newly developed thermoelastic phase damage analysis (TPDA) in which damaged area was emphasized in the differential phase delay images utilizing the property that carbon fiber shows opposite phase thermoelastic temperature change.

Development and validation of a phase analysis tool to measure interventricular mechanical dyssynchrony from gated SPECT MPI

OBJECTIVES

The purpose of this study is to develop a right-ventricular (RV) phase analysis tool which when coupled with our left ventricular (LV) phase analysis tool can provide measurement of the interventricular mechanical dyssynchrony from gated SPECT myocardial perfusion imaging (MPI), and validate the tool by electrocardiography (ECG).

METHODS

For each patient, short-axis LV and RV SPECT MPI images were input into an automatic sampling algorithm to generate the 3D maximal count circumferential profiles for both LV and RV in each cardiac frame. Subsequently, the samples of LV and RV were separately used by our phase analysis tool based on the first-harmonic Fourier approximation to calculate the contraction onset for each sample. The difference between contraction onsets of the middle LV free wall and middle LV septal wall represented the LV contraction delay; the difference between contraction onsets of the middle RV free wall and middle RV septal wall represented the RV contraction delay. The difference between the LV and RV contraction delays represented the interventricular contraction delay, which was compared with the interventricular conduction delay classified by ECG to validate the concordance of interventricular mechanical and electrical dyssynchrony. Sixty-one bundle branch block (BBB) patients with ischemic-dilated cardiomyopathy (26, 42.6%) or non-ischemic-dilated cardiomyopathy (35, 57.4%), who underwent 12-lead surface ECG and gated resting Tc-99m sestamibi SPECT, were retrospectively analyzed in this study.

RESULTS

In the 30 patients with left bundle branch block (LBBB) by ECG, there were 27 patients whose LV contracted later than the RV according to SPECT; and in the 31 patients with right bundle branch block (RBBB) by ECG, there were 26 patients whose LV contracted earlier than the RV according to SPECT. In total, an agreement rate of 86.9% (53 of 61) was achieved between SPECT and ECG. The Kappa agreement rate was 73.8% (95% confidence interval 0.57-0.91).

CONCLUSION

The preliminary results showed promise for the measurement of interventricular mechanical dyssynchrony in BBB patients with dilated cardiomyopathy using our phase analysis tool.

Impact of cardiac reverse remodeling after cardiac resynchronization therapy assessed by myocardial perfusion imaging on ventricular arrhythmia

BACKGROUND

Although cardiac resynchronization therapy (CRT) has been a useful treatment of heart failure, patients with CRT are still in risk of sudden cardiac death due to ventricular arrhythmia. The aim of this study was to investigate the impact of cardiac reverse remodeling after CRT on the prevalence of ventricular tachycardia or fibrillation (VT/VF).

METHODS AND RESULTS

Forty-one heart failure patients (26 men, age 66 ± 10 years), who were implanted with CRT for at least 12 months, were enrolled. All patients received myocardial perfusion imaging (MPI) under CRT pacing to evaluate left ventricle (LV) function, dyssynchrony, and scar. VT/VF episodes during the follow-up period after MPI were recorded by the CRT devices. Sixteen patients (N = 16/41, 39%) were found to have VT/VF. Multivariate Cox regression analysis and receiver operating characteristic curve analysis showed that five risk factors were significant predictors of VT/VF, including increased left ventricle ejection fraction (LVEF) by ≤7% after CRT, low LVEF after CRT (≤30%), change of intrinsic QRS duration (iQRSd) by ≤7 ms, wide iQRSd after CRT (≥121 ms), and high systolic dyssynchrony after CRT (phase standard deviation ≥45.6°). For those patients with all of the 5 risk factors, 85.7% or more developed VT/VF.

CONCLUSIONS

The characteristics of cardiac reverse remodeling after CRT as assessed by MPI are associated with the prevalence of ventricular arrhythmia.

Review of cardiovascular imaging in the journal of nuclear cardiology in 2016: Part 2 of 2-myocardial perfusion imaging

In 2016, the Journal of Nuclear Cardiology published many high-quality articles. Similar to previous years, we will summarize here a selection of the articles that were published in the Journal in 2016 to provide a concise review of the main advancements that have recently occurred in the field. In the first article of this two-part series we focused on publications dealing with positron emission tomography, computed tomography, and magnetic resonance. This review will place emphasis on myocardial perfusion imaging using single-photon emission-computed tomography summarizing advances in the field including in diagnosis, prognosis, and appropriate use.

The prognostic value of mechanical left ventricular dyssynchrony defined by phase analysis from gated single-photon emission computed tomography myocardial perfusion imaging among patients with coronary heart disease

BACKGROUND

The prognostic value of left ventricular dyssynchrony measured by gated single-photon emission computed tomography (GSPECT) myocardial perfusion imaging (MPI) and its relationship to electrical dyssynchrony measured by QRS duration are incompletely understood. The aim of this study was therefore to examine the independent and incremental prognostic value of dyssynchrony in yet the largest group of patients with coronary artery disease (CAD).

METHODS AND RESULTS

Patients presenting for GSPECT- MPI between July 1993 and May 1999 in normal sinus rhythm were identified from the Duke Nuclear Cardiology Databank and the Duke Databank for Cardiovascular Disease (N = 1244). After a median of 4.2 years, 336 deaths occurred. At 8 years, the Kaplan-Meier estimates of the probability of death were 34.0% among patients with a phase bandwidth <100° and 56.8% among those with a bandwidth ≥100°. After adjustment for standard clinical variables, QRS dyssynchrony was independently associated with death (Hazard Ratio (HR), per 10°: 1.092, 95% Confidence Interval (CI) 1.048,1.139, P < .0001). Phase bandwidth was similarly associated with death after clinical adjustment (HR per 10°: 1.056, 95% CI 1.041,1.072, P < .0001). In clinically adjusted models examining QRS duration in addition to phase bandwidth, phase bandwidth had a stronger association with mortality. After accounting for left ventricular ejection fraction (LVEF), neither QRS duration nor phase bandwidth were statistically significant. Among patients with EF >35%, QRS duration and phase bandwidth together provided value above that provided by LVEF alone (P = 0.0181). When examining cardiovascular death, results were consistent with all-cause death.

CONCLUSIONS

Among patients with CAD, mechanical left ventricular dyssynchrony measured by GSPECT MPI has a stronger relationship with outcomes than electrical dyssynchrony measured by QRS duration. After adjustment for baseline characteristics and LVEF, neither mechanical nor electrical dyssynchrony is independently associated with all-cause death or cardiac death. Among patients with EF >35%, mechanical and electrical dyssynchrony together provided prognostic value above that afforded by LVEF.

Right ventricular dyssynchrony in pulmonary hypertension: Phase analysis using FDG-PET imaging

BACKGROUND

Right ventricular (RV) performance in patients of pulmonary hypertension (PH) requires optimal assessment. The objective of this study is to develop phase analysis using 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) imaging as a feasible tool for evaluation of RV dyssynchrony in PH.

METHODS AND RESULTS

Fifty-four PH patients with well-characterized hemodynamic parameters were enrolled. All subjects performed FDG-PET imaging for RV phase analysis and RV function evaluation. Two-dimensional echocardiography with speckle tracking analysis was conducted to obtain RV time to peak systolic strain (PSST) as a comparison. The median contraction delay difference between RV middle free wall and septum measured by PET phase analysis (RVPDPET) was 20.12° (interquartile range, 4.99°-30.10°). The median difference of PSST between RV middle free wall and middle septal wall (RVPDEcho) measured by echocardiography was 43.98° (interquartile range, 6.25°-72.00°). RVPDPET was well correlated with RVPDEcho (r = 0.685, P < .001). RV phase standard deviation (RVSD) and histogram bandwidth (RVBW) derived from PET phase histogram were significantly correlated with cardiac index, RV ejection fraction, 6-minute walking distance, and serum N-terminal pro B-type natriuretic peptide (NT-proBNP) (RVSD: r = -0.532, P < .001; r = -0.551, P < .001; r = -0.544, P < .001; r = 0.404, P < .01; respectively, RVBW: r = -0.492, P < .001; r = -0.466, P < .001; r = -0.544, P < .001; r = 0.349, P = .01, respectively), while there were no significant correlations between RVSD and RVBW with hemodynamic parameters (right atrial pressure, right ventricular systolic pressure, right ventricular end-diastolic pressure, mean pulmonary artery pressure, and total pulmonary resistance).

CONCLUSIONS

Contraction delays between RV free wall and septum in PH measured by phase analysis and speckle tracking echocardiography were well correlated. RV dyssynchrony measured by phase analysis of FDG-PET was significantly related to RV dysfunction. Phase analysis of FDG-PET is feasible to evaluate RV mechanical dyssynchrony in patients of PH.

Determinants of left ventricular mechanical dyssynchrony in patients submitted to myocardial perfusion imaging: A cardiac CZT study

BACKGROUND

An interaction between coronary anatomy, myocardial perfusion, and left ventricular (LV) functional parameters in the development of mechanical LV dyssynchrony (LVD) has been suggested. This study examined the correlates of LVD in a large sample size of patients with known or suspected coronary artery disease (CAD) using cadmium-zinc-telluride camera.

METHODS

Six-hundred and fifty-seven consecutive patients who underwent myocardial perfusion imaging (MPI) and coronary angiography were included. Coronary stenosis >70% was considered significant. LV perfusion and functional parameters were computed from MPI images. The presence of significant LVD was evaluated by phase standard deviation and histogram bandwidth.

RESULTS

415/657 (63%) patients had significant CAD. LVD was present in 247 (38%) patients and was associated with the presence of a higher CAD burden (P < .001), more impaired measures of LV perfusion (P < .001), contractile function (P < .001), and larger LV volumes (P < .001). By multivariate analysis, the LV end-systolic volume index (P < .001) and ischemic burden (P < .001) were the strongest predictors of LVD independent of CAD extent and LV systolic dysfunction.

CONCLUSIONS

LVD is frequent in patients undergoing MPI for suspected or known CAD. Its presence is independent of CAD burden and LV systolic dysfunction, but is dependent on the presence of myocardial perfusion abnormalities and LV end-systolic volume.