Wall Motion Research Articles

Global hypokinesis in resting transthoracic echocardiography diagnosis of heart failure and coronary artery disease.

Although coronary artery disease (CAD) and heart failure (HF) are separate entities, HF is a common complication of CAD, and both CAD and HF are known causes of wall motion abnormalities (WMA) of transthoracic echocardiography (TTE). Specifically, global hypokinesis on TTE could logically be due to multivessel CAD or non-ischemic cardiomyopathy. The purpose of this study was to investigate the relationship between CAD, HF, and WMA on TTE. A single-center retrospective chart review was conducted of adults who had a resting TTE and cardiac catheterization within 30 days. We analysed the association between global hypokinesis, triple-vessel CAD, and HF diagnosis. Across 754 included patients, there was a positive association between global hypokinesis on TTE and HF diagnosis (P < .001). There was no association between global hypokinesis on TTE and triple-vessel CAD (P = .341), possibly an inverse correlation. The sensitivity of regional (R) WMAs on TTE for diagnosing CAD was generally lower in patients without heart failure (44%), while specificity was higher in these same patients (89%). There was a positive association between global hypokinesis and HF, and a possible inverse correlation between global hypokinesis and triple-vessel CAD. This could be explained by heart failure diagnosis and other diagnoses having a stronger effect on global hypokinesis than any potential effect from triple-vessel CAD. These sensitivity and specificity results for RWMA on CAD, stratified by HF diagnosis and/or global hypokinesis, can be used to inform clinical decision-making in an acute coronary syndrome case with borderline electrocardiography and/or troponin findings.

Diastolic dysfunction: assessment and implications on the single ventricle circulation.

Patients with a functionally single ventricle (SV) are palliated with a series of procedures leading to a Fontan circulation. Over the life span, a substantial proportion of SV patients develop heart failure that can arise from circulatory or ventricular failure. Diastolic dysfunction (DD) is an important determinant of adverse outcomes in SV patients. However, assessment and categorization of DD in the SV remains elusive. We review recent literature and developments in assessment of DD in the SV and its relation to clinical outcomes. DD is prevalent in the SV and associated with worse outcomes. Occult DD can be exposed with provocative testing by exercise or preload challenge during catheterization. Likewise, sensitivity to detect DD may be increased via assessment of atrial function and strain imaging. Recent studies revisiting previous concepts such as incoordinate diastolic wall motion show that these are associated with SV end-diastolic pressures and post-Fontan recovery, yielding accessible DD assessment. Emerging technologies such as ultrafast ultrasound (UFUS) can provide noninvasive assessment of myocardial stiffness, inefficient diastolic flow patterns and intraventricular pressure gradients, thereby yielding new tools and insights into diastolic myocardial and hemodynamic properties. Characterizing DD in the SV continues to have substantial limitations, necessitating synthesis of multiple parameters into an overall assessment, accounting for their change over time, and in the context of the patient's clinical status. New and emerging techniques may help advance DD assessment and the ability to track response to treatment of new targets.

Antiferromagnetic domain wall memory with neuromorphic functionality

Antiferromagnetic materials have unique properties due to their alternating spin arrangements. Their compensated magnetic order, robust against external magnetic fields, prevents long-distance crosstalk from stray fields. Furthermore, antiferromagnets with combined parity and time-reversal symmetry enable electrical control and detection of ultrafast exchange-field enhanced spin manipulation up to THz frequencies. Here we report the experimental realization of a nonvolatile antiferromagnetic memory mimicking an artificial synapse, in which the reconfigurable synaptic weight is encoded in the ratio between reversed antiferromagnetic domains. The non-volatile memory is “written” by spin-orbit torque-driven antiferromagnetic domain wall motion and “read” by nonlinear magnetotransport. We show that the absence of long-range interacting stray magnetic fields leads to very reproducible electrical pulse-driven variations of the synaptic weights.

A comprehensive MRI-based computational model of blood flow in compliant aorta using radial basis function interpolation

BackgroundProperly understanding the origin and progression of the thoracic aortic aneurysm (TAA) can help prevent its growth and rupture. For a better understanding of this pathogenesis, the aortic blood flow has to be studied and interpreted in great detail. We can obtain detailed aortic blood flow information using magnetic resonance imaging (MRI) based computational fluid dynamics (CFD) with a prescribed motion of the aortic wall.MethodsWe performed two different types of simulations—static (rigid wall) and dynamic (moving wall) for healthy control and a patient with a TAA. For the latter, we have developed a novel morphing approach based on the radial basis function (RBF) interpolation of the segmented 4D-flow MRI geometries at different time instants. Additionally, we have applied reconstructed 4D-flow MRI velocity profiles at the inlet with an automatic registration protocol.ResultsThe simulated RBF-based movement of the aorta matched well with the original 4D-flow MRI geometries. The wall movement was most dominant in the ascending aorta, accompanied by the highest variation of the blood flow patterns. The resulting data indicated significant differences between the dynamic and static simulations, with a relative difference for the patient of 7.47±14.18% in time-averaged wall shear stress and 15.97±43.32% in the oscillatory shear index (for the whole domain).ConclusionsIn conclusion, the RBF-based morphing approach proved to be numerically accurate and computationally efficient in capturing complex kinematics of the aorta, as validated by 4D-flow MRI. We recommend this approach for future use in MRI-based CFD simulations in broad population studies. Performing these would bring a better understanding of the onset and growth of TAA.

Interventricular septum involvement is related to right ventricular dysfunction in anterior STEMI patients without right ventricular infarction: a cardiovascular magnetic resonance study.

The value of cardiovascular magnetic resonance (CMR) in assessing and predicting acute right ventricular (RV) dysfunction in patients with anterior ST-segment elevation myocardial infarction (STEMI) remains ascertained. Eightyeight patients with anterior STEMI were prospectively recruited and underwent CMR examinations within one week following the coronary intervention. Patients with RV ejection fraction (RVEF) less than 2 standard deviations below the average at the center (RVEF ≤ 45.0%) were defined as having RV dysfunction. The size of infarction, segmental wall motion, and T1 and T2 mapping values of global myocardium and the interventricular septum (IVS) were measured. Predictive performance was calculated using receiver-operating characteristic curve analysis and logistic regression test. Twentytwo patients presented with RV dysfunction. The RV dysfunction group had a larger IVS infarct extent (54.28 ± 10.35 vs 33.95 ± 15.09%, P < 0.001) and lower left ventricle stroke volume index (33.93 ± 7.96 vs 42.46 ± 8.14ml/m2, P < 0.001) compared to the non-RV dysfunction group. IVS infarct extent at 48.8% best predicted the presence of RV dysfunction with an area under the curve of 0.864. Left ventricular stroke volume index (LVSVI) and IVS infarct extent were selected by stepwise multivariable logistic regression analysis. LowerLVSVI (odds ratio [OR] 0.90; 95% confidence interval [CI], 0.79 to 0.99; P = 0.044) andhigher IVS infarct extent (OR 1.16; 95% CI 1.05 to 1.33; P = 0.01) were found to be independent predictors for RV dysfunction. In patients with anterior STEMI, those with larger IVS infarct extent and worse LV function are more likely to be associated with RV dysfunction.

Decoupling the influences of chiral damping and Dzyaloshinskii-Moriya interaction in chiral magnetic domain walls

We revisit the nature and impact of both the chiral damping (CD) and Dzyaloshinskii-Moriya interaction (DMI) in uniaxial chiral ferromagnetic nanowires with broken inversion symmetry. We propose that CD, akin to its chiral energy counterpart (DMI), can be described in terms of the Lifshitz invariants permissible by the underlying symmetry of the system. This representation offers a clearer foundation for integrating CD into the dynamics of various chiral magnetic textures. We theoretically investigate the current-induced motion of chiral domain walls (DWs), driven by both spin-transfer torque and the spin Hall effect in the presence of CD. We demonstrate that it is possible to unambiguously separate the influence of CD from that of DMI by analyzing the current-induced dynamics. In particular, below the Walker breakdown (WB), the DMI does not affect the DW velocity, whereas increases in the strength of CD result in a decrease in the DW velocity. Moreover, for the spin-orbit torque driven motion, while the DMI enhances both the WB current density and the maximum attainable velocity below the WB, the CD only enhances the WB without affecting the maximum attainable velocity below the WB. Our findings open up intriguing opportunities for exploitation in exotic magnetic textures. Published by the American Physical Society 2024

The emerging role of cardiovascular magnetic resonance in the evaluation of cardiac involvement in systemic sclerosis

Abstract Systemic sclerosis (SSc) is an autoimmune rheumatic disease, characterized by vascular, inflammatory and fibrotic alterations. Cardiac involvement is the « fatal tip of the iceberg» in SSc, as it leads to high morbidity/mortality. Cardiovascular imaging modalities play an important role in the early diagnosis and treatment assessment of cardiac involvement. Echocardiography is the corner stone for evaluation of cardiac involvement, providing information about function, wall motion, pulmonary pressure, pericardium and valvular disease. It is a low-cost modality, widely available, without radiation and with great experience among cardiologists. However, it is a window and operator dependent modality and cannot provide tissue characterization information, absolutely necessary for diagnosis and treatment of cardiac involvement in SSc. Cardiovascular magnetic resonance (CMR) can perform myocardial function and tissue characterization in the same examination without radiation, has excellent reproducibility and is window and operator independent. The great advantage of CMR is the capability to assess peri- myo-vascular inflammation, myocardial ischemia and presence of replacement and diffuse myocardial fibrosis in parallel with ventricular function assessment. The modified Lake Louise criteria including T2, native T1 mapping and extracellular volume fraction (ECV) has been recently used to diagnose inflammatory cardiomyopathy. According to expert recommendations, myocardial inflammation should be considered if at least 2 indices, one T2 and one T1 parameter are positive, whereas native T1 mapping and ECV assess diffuse fibrosis or oedema, even in the absence of late gadolinium enhancement (LGE). Moreover, transmural/subendocardial LGE following the distribution of coronary arteries and diffuse subendocardial fibrosis not related with epicardial coronary arteries are indicative of epicardial and micro-vascular coronary artery disease, respectively. To conclude, CMR can overcome the limitations of echocardiography by identifying acute/active or chronic myocardial inflammation/fibrosis, ischemia and myocardial infarction using classic and parametric indices in parallel with biventricular function assessment

Evaluation of Regional Wall Motion Abnormalities with Echocardiography in the Emergency Department

Abstract Introduction Acute coronary syndrome (ACS) is a major cardiovascular disease, particularly in cases where standard electrocardiogram findings are equivocal. Focused cardiac ultrasound (FOCUS) has become increasingly accepted as a tool in emergency medicine. The primary objective of this study was to evaluate the accuracy, sensitivity, and specificity of FOCUS in detecting regional wall motion abnormalities (RWMA) compared with standard echocardiography (ECHO). Materials and Methods This prospective observational study included 91 patients who presented to the emergency department between June 1, 2023, and November 30, 2023. Senior emergency physicians performed FOCUS examinations, which were performed by an emergency assistant or specialist who works in the emergency department, has at least 2 years of experience in ultrasonography (USG), and has basic USG and advanced USG certificates. The examinations assessed the presence of RWMA in each patient's left ventricle. Results All 91 patients were included in the study for comparison with formal ECHO. The mean age was 58, and 32% of patients were female. Compared with the criterion standard of formal ECHO, the sensitivity of FOCUS performed by emergency physicians for detecting RWMA was 85% (95% confidence interval [CI], 73–92), the specificity was 53% (95% CI, 36–69), and the overall accuracy was 74% (95% CI, 64–82). Conclusion Our study demonstrates the potential utility of FOCUS performed by emergency physicians in detecting RWMA in patients with high suspicion of ACS.

Diagnostic accuracy of point-of-care cardiac ultrasound for acute coronary syndromes in patients presenting with chest pain to the emergency department: a single-center prospective study.

The diagnostic accuracy of focused cardiac ultrasound (FoCUS) performed in patients presenting to the emergency department (ED) with chest pain is currently unknown. The objective of this study was to assess the diagnostic accuracy of regional wall motion abnormalities detected with FoCUS for non-ST-elevation acute coronary syndrome (NSTE-ACS) diagnosis. A Single-center prospective observational study conducted in 2022 in the ED of the University Hospital Careggi, Italy. Adult patients presenting to the ED with acute nontraumatic chest pain were enrolled, irrespective of the presence of previous regional wall motion abnormalities. Patients with ST-segment elevation myocardial infarctions and patients with hemodynamic instability were excluded. FoCUS was performed at presentation by a trained ED physician. The final diagnosis of NSTE-ACS vs. alternative diagnosis was adjudicated by an ED physician blinded to FoCUS results after a 30-day follow-up. To assess if regional wall motion abnormalities were an independent predictor of NSTE-ACS, a multivariable logistic regression model was built. Diagnostic performance measures were calculated. A sensitivity analysis considering only type-1 NSTEMIs (i.e. plaque rupture/thrombosis) was conducted. Among 686 patients, NSTE-ACS was adjudicated in 106 (15.5%) patients, 67 of which were NSTEMIs. A total of 87 (12.7%) patients had regional wall motion abnormalities detected by FoCUS, which were an independent predictor of NSTE-ACS in the multivariable logistic regression analysis. Regional wall motion abnormalities had a sensitivity of 42.5% (33.0-51.9), a specificity of 92.8% (90.6-94.9), a negative predictive value of 89.8% (87.4-92.2), and a positive predictive value of 51.7% (41.2-62.2), for NSTE-ACS. Results were consistent in the sensitivity analysis. In ED patients with chest pain and no ST elevation, the detection of regional wall motion abnormalities was a predictor of NSTE-ACS. Despite a high specificity, which indicated a possible role of FoCUS in the rule-in of NSTE-ACS, sensitivity was too low to allow a safe rule-out using FoCUS results alone.

Quaternary piezoelectric ceramics with ultra-high mechanical quality factor

The development of piezoelectric ceramics with large piezoelectric coefficient (d33), high Curie temperature (TC) and high mechanical quality factor (Qm) is still a key challenge for practical application for high-power device. Herein, a novel quaternary piezoelectric ceramics of (0.125-x) Pb0.98Sr0.02(Mg1/3Nb2/3)O3–0.445PbTiO3–0.43PbZrO3-xPb(Mn1/3Nb2/3)O3 (abbreviated as xPMnN-PSMN-PZT) were prepared by the solid-state sintering method. The hard dopant PMnN induced the morphotropic phase boundary (MPB) of PSMN-PZT into a tetragonal-rich region. In addition, the XPS and EPR analysis proved the existence of a large amount of oxygen vacancies (Vo••) in PMnN-PSMN-PZT ceramic system. The composition near tetragonal-rich MPB region and the appearance of defect dipoles formed a strong coupling effect on the domain wall motion and leaded to an ultra Qm value. The optimum piezoelectric properties were achieved at x = 9 mol% with d33 = 260 pC/N, Qm = 3880, tanδ = 0.009 and TC = 332 °C. A significant internal bias field (Ebias) of 8.83 kV/cm was also observed in 0.09PMnN-PSMN-PZT ceramics. The origin of this excellent piezoelectric properties was explained by the phase structure, piezoelectric and dielectric analysis. This work demonstrated a rational strategy to obtain ultra Qm value for high-power piezoceramics.

Study on the high resistivity and resonant frequency characteristics of Eu-doped NiZnCo ferrites

To fulfill the urgent demand for materials suitable for contemporary high-frequency applications, Eu-substituted Ni0.55Zn0.35Co0.1EuxFe2-xO4 (NZCEF, 0 ≤ x ≤ 0.10) composite ferrites were successfully synthesized by a solid-state reaction method, demonstrating characteristics apt for high-frequency functionalities. Detailed examination via SEM and EDS confirmed the compositional purity of these ferrites. Microstructural analysis indicates that the incorporation of europium results in a reduction of the average grain size in NZCEF composites, enhancing the material's densification. Measurements of resistivity and dielectric properties reveal that Eu doping affects the concentration of Fe2+ and Fe3+ ions as well as lattice defects within the ferrite, thereby leading to higher dielectric constants and resistivity (ρ, 6.51 × 108 Ω m). Magnetic analysis confirms that the substitution with Eu ions significantly increases both the coercivity and the ferromagnetic resonance frequency (fr), from 25.7 Oe and 445 MHz to 45.73 Oe and 1.22 GHz, respectively. This improvement is attributed to changes in grain size and domain wall motion. Consequently, Eu3+-substituted NZCEF ferrites exhibit superior electromagnetic properties, making them ideal candidates for advanced high-frequency material applications.

Microwave sintering of CaBi2Nb2O9 ceramics for improved piezoelectric response and electrical resistivity

AbstractCaBi2Nb2O9 (CBN) ceramic is a promising sensing element to convert vibration to electrical signal at temperatures higher than 600°C. However, conventionally sintered ceramics suffer from poor piezoelectric coefficient (d33) and low electrical resistivity (ρdc). Here, we report that CBN ceramics can be prepared by microwave sintering (MS) to mitigate volatilization issue of Bi2O3 and thus suppress the generation of oxygen vacancies usually seen in conventional sintering (CS) as demonstrated by X‐ray photoelectron spectroscopy (XPS) analysis and mass‐loss measurement. As compared to the CS, the MS is more favorable for reducing the sintering time, and obtaining a dense, fine, and uniform grain morphology as revealed by scanning electron microscopy (SEM) characterizations of both surface and interior of the CBN ceramics, leading to an enhancement of 86% and 75% in d33 and ρdc, respectively. Piezoresponse force microscopy (PFM) as combined with Rayleigh law analysis clearly revealed that the enhancement of piezoelectric properties was attributed to the thinner domains, the higher domain wall density, and the enhanced domain wall motion in the MS‐940 samples. This study paves an important road to simultaneously improve both d33 and ρdc in CBN ceramics for developing high‐temperature vibration sensors.

1215 Cardiovascular Compromise and Hypertensive Crisis Secondary to Phaeochromocytoma

Abstract Phaeochromocytoma is a rare tumour of the chromaffin cells in the adrenal medulla, which secretes catecholamines. While associated with genetic disorders e.g., MEN-2, they tend to occur sporadically, and are often initially asymptomatic, found incidentally on imaging. Classical symptoms of Phaeochromocytoma include headaches, sweating, and palpitations, with sustained or paroxysmal hypertension which is refractory to a cocktail of antihypertensives. A variety of presentations have been reported in the literature including, but not limited to colitis, intracerebral haemorrhage, and PRES syndrome. We present a case of a 64-year-old man with an incidental left adrenal nodule. This radiologically indeterminate lesion was initially asymptomatic. Secretion studies revealed elevated metadrenaline levels, and an MIBG scan with positive avidity unveiled the lesion's pheochromocytoma nature. Whilst awaiting surgical intervention, the patient required emergency admission with a hypertensive crisis, presenting with left-sided flank pain and a blood pressure peaking at 220mmHg systolic. ECG findings were consistent with a myocardial infarction-like picture, and echocardiogram demonstrated regional wall motion abnormalities. CT coronary angiography revealed no significant coronary arterial disease – confirming that the patient’s presentation was in fact secondary to the pheochromocytoma. Pre-operative optimization is crucial for safe surgery. After the crisis, surgery was delayed by 6 weeks for cardiac rehabilitation. The patient was admitted a week before the procedure for optimal haemodynamics. Adrenalectomy proceeded as planned after alpha-blockade. A structured endocrine surgery clinic follow-up was established to assess the patient's ongoing recovery, and cardiovascular status. This case highlights cardiovascular implications of phaeochromocytoma, stressing a multidisciplinary approach for hypertensive crises and optimising outcomes.

Internal structure dependent creep motion of domain walls driven by spin-transfer torques

Internal structure dependent creep motion of domain walls driven by spin-transfer torques

Chirality-Induced Memristor of Chiral Nanostructured Half-Metallic Fe3O4 Films.

Spintronic memristors, which combine the nonvolatile characteristics of memristors with the scalability of a spin-transfer torque device, are expected to play a crucial role in advancing quantitative information processing. This field commonly relies on magnetic tunnel junctions, domain wall motion, and spin waves. Here, the discovery of chirality-induced memristor behavior in chiral nanostructured Fe3O4 films (CNFFs) is reported. These CNFFs are grown on fluorine tin oxide (FTO) substrates using enantiomeric glutamic acid (Glu) as symmetry-breaking agents and consist of arrays of oriented twisted nanofibers. At 100 K, the L-CNFF exhibits memristor behavior as a pinched hysteresis loop in the I-V curve, while the D-CNFF exhibits semiconductor behavior with constant electrical resistance. The intrinsic spin polarization of half-metallic Fe3O4 and the chirality-induced spin selectivity (CISS) are speculated to contribute to the memristor in one handedness of the chiral structure. These findings present a novel spinristor that combines the functions of a memristor and a spin-filter based on chiral structures, which may promote the development of spintronic devices.

Stability of plane Couette flow under anisotropic superhydrophobic effects

We study the linear stability of plane Couette flow subject to an anisotropic slip boundary condition that models the slip effect of parallel microgrooves with a misalignment about the direction of the wall motion. This boundary condition has been reported to be able to destabilize channel flow far below the critical Reynolds number of the no-slip case. Unlike channel flow, the no-slip plane Couette flow is known to be linearly stable at arbitrary Reynolds numbers. Nevertheless, the results show that the slip can cause linear instability at finite Reynolds numbers also. The misalignment angle of the microgrooves that maximizes the destabilizing effect is nearly π/4, and the unstable modes are of small streamwise wavenumbers and relatively large spanwise wavenumbers. The flow is always more destabilized by two slippery walls compared to a single slippery wall. These observations are in qualitative agreement with the slippery channel flow with the same boundary condition, indicating that such an anisotropic superhydrophobic effect has a rather general destabilizing effect in shear flows regardless of the profile of the base flow. The absence of the Tollmien–Schlichting instability allows us to reveal the inverse relationship between the critical Reynolds number and the slip length as well as the misalignment in the small-parameter regime. The results suggest that arbitrary nonvanishing slip length and misalignment, with arbitrarily weak anisotropy, may suffice to destabilize plane Couette flow.

Takotsubo cardiomyopathy in a 7-month-old infant with familial hemophagocytic lymphohistiocytosis: A case report

Abstract Takotsubo cardiomyopathy constitutes an acute cardiac condition that mimics acute myocardial infarction in the absence of coronary artery disease. We present a case of a 7-month-old girl, who was admitted in the pediatric intensive care unit (PICU) at a tertiary care hospital for clinical deterioration with underlying familial hemophagocytic lymphohistiocytosis. During the PICU stay, on echocardiography, the patient had severe cardiac contractility compromise with a characteristic pattern of regional wall motion abnormalities of the left ventricle. This, in combination with elevated cardiac enzymes, led to the diagnosis of takotsubo cardiomyopathy.

A study to observe the association of left ventricular ejection fraction and wall motion score index with duration of early systolic lengthening in patients with non-ST-elevation acute coronary syndrome

Background: Management of non-ST elevation myocardial infarction acute coronary syndrome (NSTEMI ACS) patients is not well defined as that of ST elevation myocardial infarction. The accuracy of results of conventional echocardiography is significantly compromised when imaging is suboptimal, myocardial damage is in small areas, and compensatory hyperkinesias of healthy segment. Aims and Objectives: Duration of early systolic lengthening (DESL) may be employed to identify early myocardial ischemia and thus, may help to prepare treatment strategies for NSTEMI patients. Materials and Methods: A total of 57 patients with NSTEMI ACS attending the cardiology department were included in the study group. Results: More than 80% of patients of NSTEMI have normal or near normal ejection fraction and wall motion score index. In our study, the DESL is prolonged in a significant number of non-ST-elevation acute coronary syndrome patients. Conclusion: As DESL is afterload independent, it is superior to global longitudinal strain in assessing myocardial damage. Several studies including ourselves show that DESL of &lt;50 ms may be the cutoff value to reveal minimal myocardial damage.

Prospective Randomized Trial Comparing 2 Devices for Deep Inspiration Breath Hold Management in Breast Radiation Therapy: Results of the BRAVEHeart Trial

Aims: The BRAVEHeart trial prospectively randomized left-sided breast cancer patients to one of two deep inspiration breath hold (DIBH) biofeedback devices: a novel chest surface tracking system and an abdominal block tracking system. The primary hypothesis was that the accuracy of chest tracking would be higher than that of abdominal tracking as the chest is a more direct surrogate of the breast target.Methods: Left-sided breast cancer patients were treated in DIBH with IMRT delivery. Patients were randomized to either the novel chest surface system or abdominal block system for active management of breath hold with visual feedback. On both trial arms the unallocated system monitored passively.239,296 cine EPID images were analyzed retrospectively to extract the chest wall position. Treatment accuracy was quantified as the deviation of the internal chest wall during treatment relative to the planned position from the digitally reconstructed radiograph. The correlation between motion of the external surrogate and internal chest wall was calculated per breath hold. Ease of use was assessed with questionnaires for both radiation therapists and patients and appointment length recorded.Results: Data from 26 participants were available for analysis. No difference was found in delivered treatment accuracy between arms. Across all patients and fractions, the median correlation between internal chest wall movement and external surrogate was 0.69 for the chest surface and 0.17 for the abdominal block. Patients found it easy to follow visual feedback from both systems. No difference was found in appointment length between arms.Conclusions: No statistical evidence was found for superior treatment accuracy, satisfaction or appointment length for the novel chest surface tracking device compared to the abdominal block system. During DIBH, the median per-breath hold correlation of internal chest wall movement to the motion of the chest surface was higher than the median correlation of the abdominal block to the chest surface.

Magnetic Barkhausen Noise: Aspects of Generation and Modeling

The Magnetic Barkhausen noise (MBN) techniquemeasures discrete changes in magnetization, known as“Barkhausen jumps”, whi ch can be seen as steps i n the hysteresis curve. When a ferro-magnetic material issubjected to an external varying magnetic field, themagnetization of the material wil l change in a non-linearway. These changes in magnetization are described by thehysteresis curve and are the result of modifications of domain structure of the material. Changes in magnetizationare caused by domain wall creation, domain wallannihilation, domain wall motion and rotation. In order toimprove the interpretation of Barkhausen noise, models areneeded which describe the dependence of magnetization on material properties.