Tracking Imaging Research Articles

Effect of Sacubitril/Valsartan and enalapril on left ventricular function in patients with hematologic malignancies after bone marrow transplantation

Abstract Background and Aims Optimizing treatment for heart failure early after initiation of chemotherapy may prevent myocardial dysfunction. We hypothesized that early initiation of treatment with sacubitril/valsartan (sac/val) or enalapril (ena) may prevent cardiotoxicity. Patients and methods 90 patients (mean age 45.7 ± 14,1 years old, 52 male) with normal LV ejection fraction, who suffered from hematologic malignancies (lymphoma, leukemia) and underwent bone marrow transplantation, were randomized to receive sacubitril/valsartan 24/26 mg bid daily or enalapril 5 mg bid daily or placebo. We measured at baseline, before transplantation and after six months: i) Global Longitudinal Strain (GLS) of left ventricle (LV) by speckle tracking imaging, ii) myocardial global work index (GWI), global constructive work (GCW), global wasted work (GWW) and myocardial global work efficiency (GWE), by longitudinal strain-peripheral blood pressure loops, and iii) Left Ventricular Ejection Fraction (LVEF). Results The 3 treatment groups had similar age, sex, risk factors and cardiotoxic medication before and after bone marrow transplantation. Compared to baseline, patients treated with sacubitril/valsartan or enalapril for six months did not show a deterioration of LV GLS (-19.8±2.8 vs -19.3±4.1%, p=0.403 for sac/val, -20.3±2.8 vs -20.0±3.6%, p=0.634 for ena). Conversely, patients treated with placebo for six months, presented a significant impairment of LV GLS (-20.9±2.1% vs -18.5±2.2, p=0,001). No significant changes were found in LVEF after treatment with sacubitril/valsartan or enalapril for six months (57.5±4.9 vs 57.9±6.8%, p=0.826 for sac/val, 58.8±5.4 vs 60.7±7.1%, p=0.419, for ena), while a borderline deterioration was noticed after treatment with placebo (60.6±5.4 vs 57.7±6.7%, p=0.045). Moreover, in the sacubitril/valsartan group, we noticed a significant reduction of left ventricular end diastolic and end-systolic volume [(102.3±26.9 vs 93.9±21.5 ml, p=0.042 and 44.5±15.4 vs 38.6±9.6ml, p=0.012), respectively]. At 6 months, we did not observe any alteration in GWi, GCW, GWW, GWE in patients treated with enalapril (p>0.05). Conversely, in patients treated with sacubitril/valsartan GWE was improved (94.2±3.1 vs 95.8±1.8 %, p=0.030) and GWW was reduced (111.5±75.7 vs 86.4±43.1 mmHg%, p=0.045), while GWI and GCW did not show any significant alteration. Conversely, in the placebo group, GWI was reduced (1909.9±336.4 vs 1727.9±340.9 mmHg%, p=0.027), GWW was increased (80.7±60.6 vs 110.6±65.1 mmHg%, p=0.045), GWE was also reduced (94.2±3.1 vs 95.8±1.8 %, p=0.030) and GCW did not change at 6 months. Conclusions Treatment with sacubitril/valsartan or enalapril prevented deterioration of myocardial function six months after bone marrow transplantation in patients with hematologic malignancies and preserved LV ejection fraction. Moreover, sacubitril/valsartan showed a more favorable effect on myocardial work.

Left atrial functional assessment a prime clue in solving the puzzle of stable angina symptoms in suspected coronary artery disease patients

Abstract Background Assessing clinically for significant coronary artery disease (CAD) in stable angina patients presents a formidable task. Routinely performed echocardiography is limited in diagnosing CAD with provision for the regional wall motion abnormality (RWMA) for left ventricle (LV) systolic dysfunction and altered mitral inflow velocities for LV diastolic dysfunction. However, the advent of two-dimensional (2D) speckle-tracking technique has established the era of strain imaging, opening new possibilities in echocardiography. It is now possible to have a detailed functional assessment of left atrium (LA). We utilised speckle tracking imaging to obtain strain parameters for LA function. Combining these strain parameters with the doppler myocardial velocities and mitral inflow velocities, may prove useful mode of imaging to diagnose significant CAD in stable angina patients. Purpose To study the parameters of left atrial functions utilising echocardiographic strain imaging and evaluate their correlation with the syntax score-II in patients with symptoms of stable angina. Methods 103 patients with symptoms of stable angina undergoing coronary angiography for suspected coronary artery disease(CAD), were considered for LA function assessment and compared with their syntax-II score. Results The LA reservoir function parameters, peak atrial longitudinal strain (PALS) and peak global systolic strain rate (LAsSR), decreased with increasing syntax-II score (p values 0.011 and 0.001 respectively) and the parameter of LA conduit function, peak global early diastolic strain rate (LAeSR) increased (p value <0.001). The LA filling pressures reflected by E/e`, also increased with more severe syntax-II score (p value <0.001). We, further, configured cut off values of < 23.56 for PALS, < 1.15 for LAsSR, > -1.09 for LAeSR, and E/e` ratio > 10.39 as predictors of significant CAD, with good sensitivity and specificity. Therefore, stable angina patients who had significant CAD on coronary angiogram represented by severe syntax score-II, had higher LA filling pressures and deranged LA function with transition from more of reservoir chamber to merely a conduit. Conclusion Our study shows a significant association between LA strain parameters (PALS, LAsSR, and LAeSR) and LA filling pressures (E/e`), with the presence of significant CAD in these patients. The stable angina patients with more severe CAD as quantified by their severe syntax score-II, have an impaired LA reservoir and LA functions more as a conduit, with elevated filling pressures. This study establishes a significant association between LA deformation strain variables and severity of CAD and hence LA strain imaging can be a useful tool to diagnose significant CAD in stable angina patients.

Relative longitudinal strain apical sparing pattern and low albumin as detrimental factors of cardiovascular outcome after transcatheter aortic valve replacement

Abstract Background Relative apical sparing pattern (RASP) of longitudinal strain (LS), a typical echocardiographic feature of cardiac amyloidosis, is associated with cardiac death or heart failure admission in severe aortic stenosis (AS) patients, and associated with all-cause death among elderly patients with severe AS undergoing transcatheter aortic valve replacement (TAVR). Purpose Present study aimed to explore clinical and echocardiographic determinants of short-term and long-term CV outcome (including CV death and CV hospitalization) in symptomatic severe AS patients after TAVR, and to assess the independent and incremental prognostic value of RASP on CV outcome in TAVR patients. Methods This retrospective study comprised 598 consecutive AS patients underwent TAVR (mean age 81.7±5.7 years, 48.7% male). Pre-operative clinical and echocardiography data, including 2D speckle tracking imaging indexes, were analyzed. Clinical outcomes included CV death and procedure related complications at 30 days, 1 year, and at 2 years after TAVR. Results Relative apical sparing pattern (RASP) of longitudinal strain (LS) was defined as ≥3 LV wall segments with the apical-basal LS ratio >3.0. The prevalence of RASP was 19.2%. Compared with patients without RASP, patients with RASP were associated with higher risk of acute kidney injury (AKI, 10.4% vs. 3.3%, P=0.001) and new-onset left bundle branch block (LBBB) after TAVR (17.4% vs. 6.8%, P<0.001) and higher 2-year CV mortality (22.6% vs. 9.9%, P<0.001, Figure 1) after TAVR. Lower pre-procedural albumin level and RASP were identified as independent determinants of increased 2-year CV mortality (RASP: HR=2.178, P=0.002; albumin<4.0g/dl: HR= 2.548, P<0.001), regardless of TAVR approach and EuroSCORE II. After adjustment, the addition of RASP significantly improved prognostic power of a model including clinical variables and low albumin level for predicting 2-year CV death (χ2 from 28.179 to 40.699, P=0.001, Figure 2). Conclusion RASP is a significant determinant of AKI and new-onset LBBB after TAVR. RASP together with low pre-procedural albumin level serve as the strongest determinants of increased risk of 2-year CV mortality after TAVR.Figure 1Figure 2

Assessment of global and segmental strain in heterozygous APE1/Ref-1 transgenic mice using cardiac magnetic resonance imaging

Abstract Background Apurinic/apyrimidinic-endonuclease1(APE1/Ref-1) is a redox factor necessary for DNA binding and transcription regulator in ROS generation. The association between APE1/Ref-1 and heart failure(HF) has been observed in previous studies. Heterozygous APE1/Ref-1 transgenic mice displayed endothelial cell dysfunction with systemic hypertension. Global strain(GS) measures the myocardium's deformation along its axis and is known to be a sensitive marker of subclinical HF in hypertensive patients with preserved ejection fraction. Purpose This study aims to investigate the functional dynamics and GS of the heart in heterozygous APE1/Ref-1 mice to help identify the association between APE1/Ref-1 and early signs of HF and translate to clinical applications. Methods A study was conducted to assess the functional parameters of both the left ventricle(LV) and right ventricle (RV) and perform LV global and segmental strain analysis using cardiac magnetic resonance imaging(CMR) in heterozygous APE1/Ref-1 transgenic mice(n=4) and wild type mice (n=4) of age 10-12 weeks. A 7T CMR scanner and FSE T1 sequence were used to acquire short-axis views of mouse cardiac images. LV and RV functional parameters including ejection fraction(EF), stroke volume(SV), cardiac output, peak filling rate, peak emptying rate and strain indices including global circumferential strain, global radial strain, segmental circumferential strain, and segmental radial strain were calculated with a software dedicated to analyzing CMR images. Global LV and RV function was quantified both manually and using an AI-based algorithm of LV and RV segmentation. The strain analysis was performed using the strain medical image tracking toolbox module. Additionally, reproducibility testing was done to validate the accuracy of AI-driven calculations. Results We found that heterozygous APE1/Ref-1 mice displayed a decrease in SV(8.00±0.01ul vs 9.75±0.96ul, p=0.01) and LVEF(58.75±2.63% vs 66.50±2.89%, p=0.007) compared to controls while the functional parameters of RV were similar. Interestingly, the circumferential strain rate of LV was significantly reduced in APE1/Ref-1 mice compared to controls(p<0.001), particularly in the systolic phase. In addition, the study showed that manually-calculated and AI-derived indices were within an acceptable margin of error, rendering the AI system reproducible and reliable in calculating volumetric parameters and strain of the mice's hearts. Conclusions This study demonstrated that LV global circumferential strain rate, along with SV and LVEF decreased in heterozygous APE1/Ref-1 transgenic mice. These parameters could serve as markers for assessing early functional changes of mice hearts in a non-invasive manner. Volumetric and strain indices measured by AI-based analysis of mouse CMR images are reproducible parameters for cardiovascular research in small animals.LV strain analysis of mice CMRTable of volumetric parameters

Assessment of Left Ventricular Systolic Function after Surgical and Transcatheter Device Closure of Ventricular Septal Defect Using Speckle Tracking Imaging

Assessment of Left Ventricular Systolic Function after Surgical and Transcatheter Device Closure of Ventricular Septal Defect Using Speckle Tracking Imaging

Compressed single-shot 3D photoacoustic imaging with a single-element transducer

Three-dimensional (3D) photoacoustic imaging (PAI) can provide rich information content and has gained increasingly more attention in various biomedical applications. However, current 3D PAI methods either involves pointwise scanning of the 3D volume using a single-element transducer, which can be time-consuming, or requires an array of transducers, which is known to be complex and expensive. By utilizing a 3D encoder and compressed sensing techniques, we develop a new imaging modality that is capable of single-shot 3D PAI using a single-element transducer. The proposed method is validated with phantom study, which demonstrates single-shot 3D imaging of different objects and 3D tracking of a moving object. After one-time calibration, while the system could perform single-shot 3D imaging for different objects, the calibration could remain effective over 7 days, which is highly beneficial for practical translation. Overall, the experimental results showcase the potential of this technique for both scientific research and clinical applications.

A High Precision Initial Position Estimation Method for Low Saliency Ratio Machine Based on Image Tracking

In sensorless control of permanent magnet synchronous motor (PMSM) drives, initial rotor position detection is critical to ensure smooth start-up operation. However, extracting initial position information for machines with ultra-low saliency ratios is challenging. To address this issue, this paper proposes an estimation method for rotor position using image tracking based on high-frequency (HF) rotating voltage vector injection. Specifically, this paper extracts positive- and negative-sequence currents in the stationary reference frame and reconstructs the induced current vector. By utilizing the support vector machine (SVM) algorithm, the resulting current vector images, which contain amplitude and phase information of the position, are trained to establish the correlation between the current image and rotor position information. Ultimately, the electric position can be obtained from image recognition. Since this method employs image tracking for position estimation, it accounts for cross saturation and multiple saliencies, leading to the relatively high precision of position estimation. Experimental evaluation shows that the proposed method achieves higher precision compared to conventional observers.

Silicon Carbide Timepix3 detector for quantum-imaging detection and spectral tracking of charged particles in wide range of energy and field-of-view

The hybrid architecture of the Timepix (TPX) family of detectors enables the use of different semiconductor sensors, most commonly silicon (Si), as well as high-density materials such as Cadmium Telluride (CdTe) or Gallium Arsenide (GaAs). For this purpose, we explore the potential of a silicon carbide (SiC) sensor bump-bonded on a Timepix3 detector as a radiation imaging and particle tracking detector. SiC stands as a radiation-hard material also with the ability to operate at elevated temperatures up to several hundreds of degrees Celsius. As a result, this sensor material is more suitable for radiation harsh environments compared to conventional e.g., Si sensors. In this work, we evaluate the response for precise radiation spectrometry and high-resolution particle tracking of newly developed SiC Timepix3 detector which is built and operated as a compact radiation camera MiniPIX-Timepix3 with integrated readout electronics. Calibration measurements were conducted with mono-energetic proton beams with energies of 13, 22, and 31 MeV at the U-120M cyclotron at the Nuclear Physics Institute Czech Academy of Science (NPI CAS), Prague, as well as 100 and 226 MeV at the Proton Therapy Center Czech (PTC) in Prague. High-resolution pattern recognition analysis and single-particle spectral tracking are used for detailed inspection and understanding of the sensor response. Results include distributions of deposited energy and linear energy transfer (LET) spectra. The spatial uniformity of the pixelated detector response is examined in terms of homogeneously distributed deposited energy.

Mitral valve prolapse—arrhythmic faces of the valve disease

Mitral valve prolapse (MVP) is a relatively common mitral valvulopathy and the most common cause of isolated primary mitral regurgitation (MR) requiring surgical repair. It affects about 1–3% of the general population. Although MVP is viewed as a benign condition, the association between MVP and sudden cardiac death (SCD) has been proven. Patients with MVP have a three times higher risk of SCD than the general population. The underlying mechanisms and predictors of arrhythmias, which occur in patients with MVP, are still poorly understood. However, some echocardiographic features such as mitral annulus disjunction (MAD), bileaflet MVP (biMVP), and papillary muscle (PM) fibrosis were frequently linked with increased number of arrhythmic events and are referred to as “arrhythmogenic” or “malignant”. Arrhythmogenic MVP (AMVP) has also been associated with other factors such as female sex, polymorphic premature ventricular contraction (PVC), abnormalities of T-waves, and Pickelhaube sign on tissue Doppler tracing of the lateral part of the mitral annulus. Cardiac magnetic resonance (CMR) imaging and speckle tracking echocardiography are new tools showing significant potential for detection of malignant features of AMVP. This paper presents various data coming from electrocardiography (ECG) analysis, echocardiography, and other imaging techniques as well as compilation of the recent studies on the subject of MVP.

4Dimensional XStrain Echocardiography: Comprehensive Evaluation of Non-obstructive Hypertrophic Cardiomyopathy- A Case Report and Review of Literature

Hypertrophic cardiomyopathy (HCM) is a relatively common inherited cardiomyopathy, which is occasionally challenging to differentiate from hypertensive heart disease and athletes heart on the basis of morphologic or functional abnormalities alone. Imaging studies provide solution for majority of clinical presentations. Generally, transthoracic echocardiography (TTE) is employed as a first line imaging tool and contrast enhanced echocardiography (CEE), contrast tuned imaging echocardiography (CTIE), cardiac magnetic resonance (CMR), cardiac computed tomography (CCT), cardiac nuclear imaging and speckle tracking echocardiography (STE) are encouraged for either suboptimal studies because of poor visualization of left ventricular (LV) cavity or for comprehensive delineation of the cardiac anatomy, its widespread left and right ventricular involvement, associations and complications. We are reporting a case of 48-year old male presenting to us with atypical chest pain and a history of suspicious solitary episode of syncope. His routine ECG was indicative of left ventricular hypertrophy with strain pattern, and his TTE was substandard and inadequate in the apical four chamber (4CH) and five chamber (5CH) views, hence CTIE was performed without the application of intravenous contrast agents, to produce a remarkable illustration of HCM.
 Keywords: Hypertrophic cardiomyopathy, contrast echocardiography, contrast tuned imaging, speckle tracking echocardiography, 4Dimensional XStrain, Non obstructive HCM

Evaluation of right heart function changes in patients with pulmonary hypertension via two-dimensional speckle tracking imaging: a retrospective study

Objective: To realize the changes in pulmonary hypertension (PH) patients’ right ventricular function.Methods: A total number of 74 patients with PH were included, and the parameters of standard echocardiographic were measured as well as the strain of peak longitudinal of each segment during the systole of the right ventricle to calculate the global longitudinal strain (LS) during systole of the right ventricular free wall.Results: ① As pulmonary arterial pressure increased, the right ventricular area gradually increased, and the case group showed the decreased right ventricular fractional area change (RVFAC), tricuspid annular plane systolic excursion (TAPSE), and tricuspid annular peak systolic velocity (S’) (p < 0.05). They, RVFAC, and TAPSE depicted significant differences that were statistical (p < 0.05) from the other groups. ② With increasing pulmonary arterial pressure, the right ventricular free wall’s LS gradually reduced (p < 0.05).Conclusion: ① LS right ventricular free wall is useful in detecting changes in right ventricular systolic function early on with greater sensitivity than RVFAC, TAPSE, and S’. In addition, increased right ventricular pressure loading can result in a subsequent impairment of right ventricular myocardial mechanics. ② As right ventricular pressure loading increases, right ventricular strain decreases. ③ In mild PH, the right ventricular free wall’s. LS is more sensitive than standard measures in spotting early alterations in myocardial mechanics.

Speckle tracking tissue motion mitral annulus displacement to assess early changes in the left ventricle and its association with lung function in patients with chronic obstructive pulmonary disease.

To evaluate the early changes in left ventricular (LV) in patients with chronic obstructive pulmonary disease (COPD) by measuring tissue motion mitral annulus displacement (TMAD) and three-dimensional (3D) parameters using speckle tracking imaging (STI), and to explore its correlation with lung function. Forty two COPD patients (GOLD I, GOLD II, GOLD III) and 30 healthy individuals (control group) were included. STI was used to assess the changes in LV structure and systolic function. Receiver operating characteristic (ROC) curves were drawn, and correlations among TMAD parameters, LV systolic function, structural, pulmonary artery systolic pressure (PASP), and lung function were analyzed. Compared to the control group, COPD patients were able to undergo LV remodeling, with a decrease in the absolute value of global longitudinal strain (GLS) and TMAD, but no significant modification of LVEF. Correlation analysis showed that TMAD was positively related to the absolute value of GLS (r > 0.51, P < 0.01) and predicted forced expiratory volume in the first second (FEV1%) (r > 0.56, P < 0.01), and negatively to PASP (r < -0.52, P < 0.01). The LV posterior wall thickness (LVPWd), relative wall thickness (RWT), end-diastolic volume (LVEDV) and PASP negatively correlated with FEV1%. The LV geometric changes and systolic function impairment in COPD patients were found to correlate with airflow restriction (FEV1%). TMAD aided in detection of early changes in LV systolic function in COPD patients. It negatively correlated with PASP and positively with FEV1%. Moreover, it was more convenient than GLS.

Endocytosis-mediated entry of a caterpillar effector into plants is countered by Jasmonate

Insects and pathogens release effectors into plant cells to weaken the host defense or immune response. While the imports of some bacterial and fungal effectors into plants have been previously characterized, the mechanisms of how caterpillar effectors enter plant cells remain a mystery. Using live cell imaging and real-time protein tracking, we show that HARP1, an effector from the oral secretions of cotton bollworm (Helicoverpa armigera), enters plant cells via protein-mediated endocytosis. The entry of HARP1 into a plant cell depends on its interaction with vesicle trafficking components including CTL1, PATL2, and TET8. The plant defense hormone jasmonate (JA) restricts HARP1 import by inhibiting endocytosis and HARP1 loading into endosomes. Combined with the previous report that HARP1 inhibits JA signaling output in host plants, it unveils that the effector and JA establish a defense and counter-defense loop reflecting the robust arms race between plants and insects.

Optimized Red-Absorbing Dyes for Imaging and Sensing.

Rhodamine dyes are excellent scaffolds for developing a broad range of fluorescent probes. A key property of rhodamines is their equilibrium between a colorless lactone and fluorescent zwitterion. Tuning the lactone-zwitterion equilibrium constant (KL-Z) can optimize dye properties for specific biological applications. Here, we use known and novel organic chemistry to prepare a comprehensive collection of rhodamine dyes to elucidate the structure-activity relationships that govern KL-Z. We discovered that the auxochrome substituent strongly affects the lactone-zwitterion equilibrium, providing a roadmap for the rational design of improved rhodamine dyes. Electron-donating auxochromes, such as julolidine, work in tandem with fluorinated pendant phenyl rings to yield bright, red-shifted fluorophores for live-cell single-particle tracking (SPT) and multicolor imaging. The N-aryl auxochrome combined with fluorination yields red-shifted Förster resonance energy transfer (FRET) quencher dyes useful for creating a new semisynthetic indicator to sense cAMP using fluorescence lifetime imaging microscopy (FLIM). Together, this work expands the synthetic methods available for rhodamine synthesis, generates new reagents for advanced fluorescence imaging experiments, and describes structure-activity relationships that will guide the design of future probes.

Label-free image scanning microscopy for kHz super-resolution imaging and single particle tracking.

We report the modification of a label-free image scanning microscope (ISM) to perform asynchronous 2D imaging at up to 24kHz while keeping the lateral resolution gain and background rejection of a regular label-free ISM setup. Our method uses a resonant mirror oscillating at 12kHz for one-direction scanning and a chromatic line for instantaneous scanning in the other direction. We adapt optical photon reassignment in this scanning regime to perform fully optical super-resolution imaging. We exploit the kHz imaging capabilities of this confocal imaging system for single nanoparticle tracking down to 20 nm for gold and 50 nm for silica particles as well as imaging freely moving Lactobacillus with improved resolution.

Tribological behavior and wear mechanism of nanomultilayer AlCrN/AlTiSiN coatings at elevated temperatures

Wear resistance is a critical property of tool coatings for high-speed machining, which depends on mechanical properties and oxidation resistance of the coatings. Many works have demonstrated that AlTiSiN coating has good mechanical properties. Additionally, AlCrN coating exhibits excellent oxidation resistance. The multilayered structure has proved to improve comprehensive properties of the coatings. Therefore, AlCrN/AlTiSiN multilayer coating has a high potential to be used in machining applications. This paper focuses on the high-temperature tribological behavior of AlCrN/AlTiSiN multilayer coating. The results show that AlCrN/AlTiSiN coating exhibits good to acceptable wear resistance up to 800 °C. Meanwhile, AlCrN/AlTiSiN coating also displays the lowest friction coefficient of ∼0.5 and a wear rate of 1.8 × 10−6 mm3/N m at 800 °C, which is about 58.13% and 64.0% lower than that of AlCrN and AlTiSiN coatings, respectively. The imaging and composition analysis of the high-temperature wear tracks allowed for explaining the differences in wear mechanisms. At 800 °C, a dense thin tribofilm is formed on the surface of AlCrN/AlTiSiN coating, which acts as a glaze layer to impede wear. It provides a strategy for enhancing the wear resistance of monolayer coating in high temperatures, which combines the advantages of both high oxidation resistance of one layer and high hardness of the other layer.

MAxSIM: multi-angle-crossing structured illumination microscopy with height-controlled mirror for 3D topological mapping of live cells

Mapping 3D plasma membrane topology in live cells can bring unprecedented insights into cell biology. Widefield-based super-resolution methods such as 3D-structured illumination microscopy (3D-SIM) can achieve twice the axial ( ~ 300 nm) and lateral ( ~ 100 nm) resolution of widefield microscopy in real time in live cells. However, twice-resolution enhancement cannot sufficiently visualize nanoscale fine structures of the plasma membrane. Axial interferometry methods including fluorescence light interference contrast microscopy and its derivatives (e.g., scanning angle interference microscopy) can determine nanoscale axial locations of proteins on and near the plasma membrane. Thus, by combining super-resolution lateral imaging of 2D-SIM with axial interferometry, we developed multi-angle-crossing structured illumination microscopy (MAxSIM) to generate multiple incident angles by fast, optoelectronic creation of diffraction patterns. Axial localization accuracy can be enhanced by placing cells on a bottom glass substrate, locating a custom height-controlled mirror (HCM) at a fixed axial position above the glass substrate, and optimizing the height reconstruction algorithm for noisy experimental data. The HCM also enables imaging of both the apical and basal surfaces of a cell. MAxSIM with HCM offers high-fidelity nanoscale 3D topological mapping of cell plasma membranes with near-real-time ( ~ 0.5 Hz) imaging of live cells and 3D single-molecule tracking.

Ultra-fast multi-parametric 4D-MRI image reconstruction for real-time applications using a downsampling-invariant deformable registration (D2R) model

Background and purposeMotion estimation from severely downsampled 4D-MRI is essential for real-time imaging and tumor tracking. This simulation study developed a novel deep learning model for simultaneous MR image reconstruction and motion estimation, named the Downsampling-Invariant Deformable Registration (D2R) model. Materials and methodsForty-three patients undergoing radiotherapy for liver tumors were recruited for model training and internal validation. Five prospective patients from another center were recruited for external validation. Patients received 4D-MRI scans and 3D MRI scans. The 4D-MRI was retrospectively down-sampled to simulate real-time acquisition. Motion estimation was performed using the proposed D2R model. The accuracy and robustness of the proposed D2R model and baseline methods, including Demons, Elastix, the parametric total variation (pTV) algorithm, and VoxelMorph, were compared. High-quality (HQ) 4D-MR images were also constructed using the D2R model for real-time imaging feasibility verification. The image quality and motion accuracy of the constructed HQ 4D-MRI were evaluated. ResultsThe D2R model showed significantly superior and robust registration performance than all the baseline methods at downsampling factors up to 500. HQ T1-weighted and T2-weighted 4D-MR images were also successfully constructed with significantly improved image quality, sub-voxel level motion error, and real-time efficiency. External validation demonstrated the robustness and generalizability of the technique. ConclusionIn this study, we developed a novel D2R model for deformation estimation of downsampled 4D-MR images. HQ 4D-MR images were successfully constructed using the D2R model. This model may expand the clinical implementation of 4D-MRI for real-time motion management during liver cancer treatment.

Associations between ECG Changes and Echocardiographic Findings in Patients with Acute Non-ST Elevation Myocardial Infarction

Background: STEMI shows specific ECG changes due to sudden coronary blockage, but NSTEMI has varied ECG characteristics, including ST depressions and T wave inversions. Echocardiography, especially tissue Doppler imaging and speckle tracking, is crucial for diagnosing and predicting outcomes in acute coronary syndrome. The study aims to correlate ECG changes with echocardiographic findings in NSTEMI, offering potential diagnostic insights. Objective: The study aims to connect ECG alterations with echocardiographic findings in NSTEMI patients. Methods and Materials: This cross-sectional study took place from January to June 2023 at a Mymensingh Medical College Hospital, Mymensingh, Bangladesh. The research included 109 NSTEMI patients, both with and without cardiac history. Inclusion criteria were age above 30 and ischemic type of chest pain. Results: Out of 109 admitted patients, 67.4% were male and 6.4% were female. The average age was 54.34 ± 2.31 years, and prevalent conditions included 7.3% with diabetes, 11% with dyslipidemia, and 0.9% with edema, while 73% had a family history of ischemia. Conclusion: There were inconsistencies between the ECG and Echo in identifying the site of the infraction in the MI patients. Pulmonary hypertension, infection, ischemic stroke, and inferonasal regional wall motion abnormalities. Maximum no association was found in ECG changes and echocardiographic findings with acute non-ST elevation myocardial infarction.

The Effect of Spatial Velocity Gradients on Block-Matching Accuracy for Ultrasound Velocimetry

Block matching serves as the foundation for ultrasound velocimetry techniques such as blood speckle tracking and echo-particle image velocimetry. Any spatial velocity gradients (SVGs) inside a block-matching pair will result in tracking error, due to both the finite block size and the ultrasound point-spread-function. We assess, using an in silico sinusoidal flow phantom, the effect of SVG magnitude and beam-to-flow angle on block-matching bias and precision. Secondarily we assess the effect that SVGs have on velocimetry bias when using angled plane-wave compounding. The magnitude and angle of SVGs were varied by adjusting the wavelength and direction of a sinusoidal flow profile. Scatterers displaced by this flow profile were used for simulating ultrasound radio frequency data at discrete time points. After beamforming, the 2-D flow field was estimated using block matching. Two imaging sequences were tested, a single plane-wave and a three-angled plane-wave. Smaller sinusoidal flow wavelengths resulted in increased bias and reduced precision, revealing an inverse relationship between sinusoidal flow wavelength and tracking error, with median errors ranging from 69%-90% for the smallest flow wavelengths (highest SVGs) down to 3%-5% for the largest (lowest SVGs). The SVG angle was also important, in which lateral SVGs (with axially oriented flows) resulted in significant speckle decorrelation and high tracking errors in regions with high SVGs. Conversely, axial SVGs (laterally oriented flow) experienced higher bias in the peak velocity regions of the flow profile. Coherent compounding resulted in higher velocity errors than using a single transmission for lateral SVGs but not for axial SVGs. The highest SVGs that could be measured with ≤10% error was when the sinusoidal flow wavelength was less than 20 times the ultrasound pulse wavelength. The clinical significance is that the high SVGs present in high kinetic energy flows, such as severe carotid stenosis and aortic regurgitation, will limit the ability to accurately quantify the velocities in these flow structures.