Myocardial Strain for the Differentiation of Myocardial Involvement in the Post-Acute Sequelae of COVID-19-A Multiparametric Cardiac MRI Study.

Myocardial involvement was shown to be associated with an unfavorable prognosis in patients with COVID-19, which could lead to fatal outcomes as in myocardial injury-induced arrhythmias and sudden cardiac death. We hypothesized that magnetic resonance imaging (MRI) myocardial strain parameters are sensitive markers for identifying subclinical cardiac dysfunction associated with myocardial involvement in the post-acute sequelae of COVID-19 (PASC). This study evaluated 115 subjects, including 65 consecutive COVID-19 patients, using MRI for the assessment of either post-COVID-19 myocarditis or other cardiomyopathies. Subjects were categorized, based on the results of the MRI exams, as having either 'suspected' or 'excluded' myocarditis. A control group of 50 matched individuals was studied. Along with parameters of global cardiac function, the MRI images were analyzed for measurements of the myocardial T1, T2, extracellular volume (ECV), strain, and strain rate. Based on the MRI late gadolinium enhancement and T1/T2/ECV mappings, myocarditis was suspected in 7 out of 22 patients referred due to concern of myocarditis and in 9 out of 43 patients referred due to concern of cardiomyopathies. The myocardial global longitudinal, circumferential, and radial strains and strain rates in the suspected myocarditis group were significantly smaller than those in the excluded myocarditis group, which in turn were significantly smaller than those in the control group. The results showed significant correlations between the strain, strain rate, and global cardiac function parameters. In conclusion, this study emphasizes the value of multiparametric MRI for differentiating patients with myocardial involvement in the PASC based on changes in the myocardial contractility pattern and tissue structure.

The moderating role of just culture between nursing practice environment and oncology nurses' silent behaviors toward patient safety: A multicentered study.

BACKGROUND: Patient safety is a critical part of healthcare delivery that must be prioritized to guarantee optimal patient outcomes. Oncology nursing is a specialized area of nursing that demands great focus on patient safety because of the high-risk nature of this patient group. Nurses play an important role in ensuring that patients receive safe and effective care. However, the nursing practice environment can have a substantial impact on how nurses respond to patient safety problems. A just culture can promote open communication and identify potential safety issues, whereas a culture of silence can have a negative impact on patient outcomes. OBJECTIVE: Firstly, assess the relationship between the nursing practice environment and oncology nurses' silent behavior towards patient safety. Secondly, the interaction effect of just culture as a moderator in this relationship. METHOD: A cross-sectional, correctional research design was employed. Data was collected from 303 nurses working at the oncology departments of five hospitals in Egypt using three questionnaires. Data was analyzed using SPSS-PROCESS Macro (v4.2). RESULTS: There was a moderate, negative, and significant correlation between the nurse practice environment and silent behavior of nurses towards patient safety. The interaction effect of just culture with nurse practice environment strengthens this relationship, thus enhancing errors reporting. CONCLUSIONS: This study emphasized on the importance of creating a just culture that facilitates open communication and eliminating the potential hazards result from nurses' silence. Thus, oncology nurses must be encouraged to report issues related to patient safety.

Collaborative leadership and productive work performance: The mediating role of nurses' innovative behavior.

AIM: This study aims to explore the relationship between collaborative leadership and nurses' productive work performance as well as the mediating role of nurses' innovative behavior in this relationship. BACKGROUND: Collaborative leadership is an imperative necessity in the contemporary turbulent healthcare environment as it provides a collaborative atmosphere where innovative behavior and productive performance of nurses are fostered, hence moving healthcare organizations toward competitiveness and sustainability. METHOD: A cross-sectional descriptive correlational exploratory research design was used to conduct the study. Data were collected from 550 nurses recruited from three large university hospitals in Alexandria, Egypt, using three instruments, namely, interprofessional collaborative leadership in healthcare teams scale, productive work performance questionnaire, and innovative behavior inventory. The instruments of the study are Likert-type questionnaires through which nurses' perspectives regarding study variables were investigated. We used descriptive statistics, inferential statistics as well as structured equation modeling (SEM). RESULTS: SEM revealed that collaborative leadership accounted for 83% of the variance of individual productive work performance and 77% of the variance of nurses' innovative behavior. Moreover, nurses' innovative behavior partially mediates the relationship between collaborative leadership and their productive work performance. CONCLUSION: Collaborative leadership practices are powerful strategies to enhance the innovative behavior of nurses and sustain their productive work performance. IMPLICATIONS FOR NURSING AND HEALTH POLICY: Fostering a collaborative atmosphere in workplace is mandatory for nurses' innovativeness. Replacing hierarchal leadership styles with collaborative ones is a promising strategy to enhance the productive performance of nurses. Healthcare managers and leaders could cultivate an interprofessional collaborative culture in the workplace in order to sustain productivity and eradicate counterproductive work behaviors among healthcare providers.

2nd Window NIR Imaging of Radiation Injury Mitigation Provided by Reduced Notch-Dll4 Expression on Vasculature.

PURPOSE: Vascular endothelium plays a central role in the pathogenesis of acute and chronic radiation injuries, yet the mechanisms which promote sustained endothelial dysfunction and contribute to late responding organ failure are unclear. We employed 2nd window (> 1100 nm emission) Near-Infrared (NIR) imaging using indocyanine green (ICG) to track and define the role of the notch ligand Delta-like ligand 4 (Dll4) in mediating vascular injury in two late-responding radiosensitive organs: the lung and kidney. PROCEDURES: Consomic strains of female Salt Sensitive or SS (Dll4-high) and SS with 3rd chromosome inherited from Brown Norway, SS.BN3 (Dll4-low) rats at ages 11-12 weeks were used to demonstrate the impact of reduced Dll4 expression on long-term vascular integrity, renal function, and survival following high-dose 13 Gy partial body irradiation at 42- and 90 days post-radiation. 2nd window dynamic NIR fluorescence imaging with ICG was analyzed with physiology-based pharmacokinetic modeling and confirmed with assays of endothelial Dll4 expression to assess the role of endogenous Dll4 expression on radiation injury protection. RESULTS: We show that SS.BN3 (Dll4-low) rats are relatively protected from vascular permeability disruption compared to the SS (Dll4-high) strain. We further demonstrated that SS.BN3 (Dll4-low) rats have reduced radiation induced loss of CD31+ vascular endothelial cells, and increased Dll4 vascular expression is correlated with vascular dysfunction. CONCLUSIONS: Together, these data suggest Dll4 plays a key role in pathogenesis of radiation-induced vascular injury to the lung and kidney.

Effect of an educational program about mentorship competencies on nurse mentors' performance: a quasi-experimental study.

BACKGROUND: Mentorship is a vital part of the nursing profession to improve role transition, job satisfaction, and job retention while facilitating socialization, emotional well-being, and the acquisition of new skills. AIM: The present study aimed to evaluate the effect of an educational program about mentorship competencies on nurse mentors' performance at Port Said Healthcare Authority hospitals. METHODS: A quasi-experimental study design (pre-test and post-test one group) was used to conduct the study at seven Healthcare Authority hospitals in Port Said Governorate, Egypt. The study subjects were consisted of a purposive sample of 30 nurse mentors and 60 intern nursing students. Data were collected using three tools consisted of the Mentor Knowledge Questionnaire, Mentor Competencies Instrument (MCI), and Nurse Mentor Performance Assessment. Data analysis was performed using SPSS version 20, Student's t-test was used to measure differences between the pretest and post-test, and Qualitative categorical variables were compared using the chi-square test. A significant level value was considered when the p-value ≤ 0.05, and Cohen's d was used to measure the effect size. RESULTS: the post-test scores of mentorship competencies and performance after implementation of the educational program significantly improved in the studied nurse mentors 56.1 ± 13.2, 60.5 ± 4.9 compared with pre-test scores with 37.1 ± 4.1, 49.7 ± 6.9 (P < 0.001). As determined by Cohen's d test, the effect size of an educational program is quite large on the nurse mentors' performance. CONCLUSION: The educational program about mentorship competencies was significantly improve mentorship performance of the studied nurse mentors. The study recommended dissemination and generalization of the new and innovative mentorship program to the different stages of nursing education to foster the continued growth and development of nurse mentors and nurse students. Also, recommended developing a valid mentor assessment instrument consisting of and specific to the Egyptian context to assess the Egyptian mentorship model. TRIAL REGISTRATION NUMBER (TRN): The study protocol was approved by the Research Ethics Committee of the Faculty of Nursing, Port Said University (code number: NUR 13/2/2022) [10].

Profibrotic COVID-19 subphenotype exhibits enhanced localized ER-dependent HSP47+ expression in cardiac myofibroblasts in situ.

We recently described a subgroup of autopsied COVID-19 subjects (∼40%), termed 'profibrotic phenotype,' who exhibited clusters of myofibroblasts (Mfbs), which were positive for the collagen-specific chaperone heat shock protein 47 (HSP47+) in situ. This report identifies increased, localized (hot spot restricted) expression of αSMA, COLα1, POSTN and FAP supporting the identity of HSP47+ cells as myofibroblasts and characterizing a profibrotic extracellular matrix (ECM) phenotype. Coupled with increased GRP78 in COVID-19 subjects, these data could reflect induction of the unfolded protein response for mitigation of proteostasis (i.e., protein homeostasis) dysfunction in discrete clusters of cells. ECM shifts in selected COVID-19 subjects occur without significant increases in either global trichrome positive staining or myocardial injury based quantitively on standard H&E scoring. Our findings also suggest distinct mechanism(s) for ECM remodeling in the setting of SARS-CoV-2 infection. The ratio of CD163+/CD68+ cells is increased in hot spots of profibrotic hearts compared with either controls or outside of hot spots in COVID-19 subjects. In sum, matrix remodeling of human COVID-19 hearts in situ is characterized by site-restricted profibrotic mediated (e.g., HSP47+ Mfbs, CD163+ Mφs) modifications in ECM (i.e., COLα1, POSTN, FAP), with a strong correlation between COLα1 and HSP47+cells within hot spots. Given the established associations of viral infection (e.g., human immunodeficiency virus; HIV), myocardial fibrosis and sudden cardiac death, early screening tools (e.g., plasma biomarkers, noninvasive cardiac magnetic resonance imaging) for diagnosis, monitoring and treatment of fibrotic ECM remodeling are warranted for COVID-19 high-risk populations.

A modified angled plate for fixation of proximal femoral varus osteotomy in neuromuscular hip dislocation: Mechanical and clinical study.

INTRODUCTION: Proximal femoral osteotomy is an important step in the management of paralytic hip dislocation. Fixation by the angled plate is demanding and carries the risk of many complications. In this study, we made certain modifications for the angled plate. Does this plate provide a stable fixation for proximal femoral varus osteotomy? The main objective of this study was to assess the results of the modified plate in fixation of proximal femoral varus osteotomy in patients with neuromuscular hip dislocation. HYPOTHESIS: This new system would offer significant advantages over the existing systems in terms of easy application and stable fixation. MATERIAL AND METHODS: Twenty patients with paralytic hip dislocation were included in this study. The ages ranged from 5 to 15 years with a mean of 8.88±2.92 years. There were 12 boys and 8 girls. Seventeen patients had cerebral palsy and 3 had meningocele disease. Preoperative radiographs were done, and the migration percentage (MP), acetabular index (AI), and neck-shaft angle (NSA) were measured. All patients were treated with open reduction, pelvic osteotomy, and proximal femoral varus osteotomy. The femoral osteotomy was fixed by the modified angled plate in all cases. RESULTS: The osteotomy sites united in all patients and the mean time of union was 2.9±0.65 months. The acetabular index, migration percentage, and neck-shaft angle were reduced postoperatively. This reduction was statistically significant. The hips remained stable throughout the period of follow-up in all patients. No cases were complicated by non-union or implant failure. CONCLUSION: The modified angled plate (canulated interlocking blade Plate 90°) is a good method for the fixation of proximal femoral varus osteotomy in the management of neuromuscular hip dislocation. It provides a stable fixation. LEVEL OF EVIDENCE: IV; case series.

Real-Time Strain-Encoding Cardiovascular MRI for Assessment of Regional Heart Function in Tetralogy of Fallot Patients.

BACKGROUND: Tetralogy of Fallot (ToF) is the most common form of cyanotic congenital heart disease, where right ventricular (RV) function is an important determinant of subsequent intervention. OBJECTIVE: In this study, we evaluate the feasibility of fast strain-encoding (fastSENC; a one-heartbeat sequence) magnetic resonance imaging (MRI) for assessing regional cardiac function in ToF. METHOD: FastSENC was implemented to characterize regional circumferential (Ecc) and longitudinal (Ell) strains in the left ventricle (LV) and RV in post-repair ToF. Data analysis was conducted to compare strain measurements in the RV to those in the LV, as well as to those generated by the MRI Tissue-Tracking (MRI-TT) technique, and to assess the relationship between strain and ejection fraction (EF). RESULTS: Despite normal LVEF (55±8.5%), RVEF was borderline (46±6.4%), but significantly lower than LVEF. RV strains (RV-Ell=-20.2±2.9%, RV-Ecc=-15.7±6.4%) were less than LV strains (LV-Ell=-21.7±3.7%, LV-Ecc=-18.3±4.7%), and Ell was the dominant strain component. Strain differences between fastSENC and MRI-TT were less significant in RV than in LV. There existed moderate and weak correlations for RV-Ecc and RV-Ell, respectively, against RVEF. Compared to LV strain, RV strain showed regional heterogeneity with a trend for reduced strain from the inferior to anterior regions. Inter-ventricular strain delay was larger for Ell (64±47ms) compared to Ecc (36±40ms), reflecting a trend for contraction dyssynchrony. CONCLUSION: FastSENC allows for characterizing subclinical regional RV dysfunction in ToF. Due to its sensitivity for evaluating regional myocardial contractility patterns and real-time imaging capability without the need for breath-holding, fastSENC makes it more suitable for evaluating RV function in ToF.

Aortic Remodeling Kinetics in Response to Coarctation-Induced Mechanical Perturbations.

Background: Coarctation of the aorta (CoA; constriction of the proximal descending thoracic aorta) is among the most common congenital cardiovascular defects. Coarctation-induced mechanical perturbations trigger a cycle of mechano-transduction events leading to irreversible precursors of hypertension including arterial thickening, stiffening, and vasoactive dysfunction in proximal conduit arteries. This study sought to identify kinetics of the stress-mediated compensatory response leading to these alterations using a preclinical rabbit model of CoA. Methods: A prior growth and remodeling (G&R) framework was reformulated and fit to empirical measurements from CoA rabbits classified into one control and nine CoA groups of various severities and durations (n = 63, 5-11/group). Empirical measurements included Doppler ultrasound imaging, uniaxial extension testing, catheter-based blood pressure, and wire myography, yielding the time evolution of arterial thickening, stiffening, and vasoactive dysfunction required to fit G&R constitutive parameters. Results: Excellent agreement was observed between model predictions and observed patterns of arterial thickening, stiffening, and dysfunction among all CoA groups. For example, predicted vascular impairment was not significantly different from empirical observations via wire myography (p-value > 0.13). Specifically, 48% and 45% impairment was observed in smooth muscle contraction and endothelial-dependent relaxation, respectively, which were accurately predicted using the G&R model. Conclusions: The resulting G&R model, for the first time, allows for prediction of hypertension precursors at neonatal ages that is currently challenging to examine in preclinical models. These findings provide a validated computational tool for prediction of persistent arterial dysfunction and identification of revised severity-duration thresholds that may ultimately avoid hypertension from CoA.

Temporal evolution of mechanical stimuli from vascular remodeling in response to the severity and duration of aortic coarctation in a preclinical model.

Coarctation of the aorta (CoA) is one of the most common congenital cardiovascular diseases. CoA patients frequently undergo surgical repair, but hypertension (HTN) is still common. The current treatment guideline has revealed irreversible changes in structure and function, yet revised severity guidelines have not been proposed. Our objective was to quantify temporal alterations in mechanical stimuli and changes in arterial geometry in response to the range of CoA severities and durations (i.e. age of treatment) seen clinically. Rabbits were exposed to CoA resulting in peak-to-peak blood pressure gradient (BPGpp) severities of ≤ 10, 10-20, and ≥ 20 mmHg for a duration of ~ 1, 3, or 20 weeks using permanent, dissolvable, and rapidly dissolvable sutures. Elastic moduli and thickness were estimated from imaging and longitudinal fluid-structure interaction (FSI) simulations were conducted at different ages using geometries and boundary conditions from experimentally measured data. Mechanical stimuli were characterized including blood flow velocity patterns, wall tension, and radial strain. Experimental results show vascular alternations including thickening and stiffening proximal to the coarctation with increasing severity and/or duration of CoA. FSI simulations indicate wall tension in the proximal region increases markedly with coarctation severity. Importantly, even mild CoA induced stimuli for remodeling that exceeds values seen in adulthood if not treated early and using a BPGpp lower than the current clinical threshold. The findings are aligned with observations from other species and provide some guidance for the values of mechanical stimuli that could be used to predict the likelihood of HTN in human patients with CoA.

Collagen-Specific HSP47+ Myofibroblasts and CD163+ Macrophages Identify Profibrotic Phenotypes in Deceased Hearts With SARS-CoV-2 Infections.

Background Cardiac fibrosis complicates SARS-CoV-2 infections and has been linked to arrhythmic complications in survivors. Accordingly, we sought evidence of increased HSP47 (heat shock protein 47), a stress-inducible chaperone protein that regulates biosynthesis and secretion of procollagen in heart tissue, with the goal of elucidating molecular mechanisms underlying cardiac fibrosis in subjects with this viral infection. Methods and Results Using human autopsy tissue, immunofluorescence, and immunohistochemistry, we quantified Hsp47+ cells and collagen α 1(l) in hearts from people with SARS-CoV-2 infections. Because macrophages are also linked to inflammation, we measured CD163+ cells in the same tissues. We observed irregular groups of spindle-shaped HSP47+ and CD163+ cells as well as increased collagen α 1(I) deposition, each proximate to one another in "hot spots" of ≈40% of hearts after SARS-CoV-2 infection (HSP47+ P<0.05 versus nonfibrotics and P<0.001 versus controls). Because HSP47+ cells are consistent with myofibroblasts, subjects with hot spots are termed "profibrotic." The remaining 60% of subjects dying with COVID-19 without hot spots are referred to as "nonfibrotic." No control subject exhibited hot spots. Conclusions Colocalization of myofibroblasts, M2(CD163+) macrophages, and collagen α 1(l) may be the first evidence of a COVID-19-related "profibrotic phenotype" in human hearts in situ. The potential public health and diagnostic implications of these observations require follow-up to further define mechanisms of viral-mediated cardiac fibrosis.

Clinical, Experimental, and Computational Validation of a New Doppler-Based Index for Coarctation Severity Assessment.

BACKGROUND: Long-term morbidity including hypertension often persists in coarctation patients despite current guidelines. Coarctation severity can be invasively assessed via peak-to-peak catheter pressure gradient (PPCG), which is estimated noninvasively via simplified Bernoulli equation and conventionally reported as peak instantaneous Doppler gradient (PIDG). However, underlying simplifications of the equation limit diagnostic accuracy. We studied the diagnostic performance of a new Doppler-based diastolic index called the continuous flow pressure gradient (CFPG) versus conventional indices in assessing coarctation severity. METHODS: In a rabbit model mimicking human aortic coarctation, temporal blood pressure waveforms revealed the diastolic instantaneous pressure gradients and spectral Doppler features impacted by coarctation severity. We therefore hypothesized that CFPG provides superior correlation with coarctation gradients measured invasively. PIDG and CFPG were quantified using color flow echocardiography in humans and rabbits with discrete coarctations. Results were compared with PPCG in rabbits (n = 34) and arm-leg systolic gradients (n = 25) in humans via 1-way analysis of variance, Pearson's correlation, linear regression, and Bland-Altman analysis. RESULTS: A threshold of CFPG ≥ 4.6 mm Hg was identified via the Youden index as representative of PPCG ≥ 20 mm Hg (the current guideline value for coarctation intervention) in rabbits, while a CFPG ≥1.0 mm Hg represented an arm-leg systolic gradient ≥20 mm Hg in humans. Accuracy measures revealed superior correlation of CFPG (R2 > 0.80) and mild receiver operating characteristic improvement (area under the receiver operating characteristic curve, 0.94-0.95) compared with PIDG (R2 < 0.63; area under the receiver operating characteristic curve, 0.89-0.95). Inter-/intraobserver variability tested by intraclass correlation coefficient revealed measurement reliability with differences ≤8.2% and 10.7%, respectively. Computational simulations of anesthetized versus conscious hemodynamics showed parameters were minimally impacted by isoflurane inherent in the data used to derive CFPG. These results confirm the potential diagnostic accuracy of CFPG in echocardiography-based coarctation severity assessment. We are optimistic that CFPG will be useful for translation of results from preclinical studies that revisit current guidelines to limit morbidity in humans with aortic coarctation.

The Effect of Career Plateauing as a Mediating Factor on Nurses' Job Satisfaction and Promotability.

AIM: The aim of this study was to investigate the effect of career plateau as a mediating factor on nurses' job satisfaction and promotability. BACKGROUND: A nurse's career, as well as other professionals, may arrive at a point where further hierarchical development is limited. Nurses may remain longer than expected in the same position within an organization and may be plateaued, resulting in career dissatisfaction, job dissatisfaction, and turnover. METHODS: This is a descriptive correlational study. Two hundred twenty-one nurses were recruited from 1 university hospital in Egypt. Respondents completed the self-administered, printed questionnaires. Measures included career plateau, job satisfaction, and promotability questionnaires. Findings were investigated via descriptive and inferential statistics as well as structured equation modeling to examine the mediating effect of career plateauing on job satisfaction and promotability. RESULTS: The mean scores of job satisfaction, career plateauing, and promotability were 3.09 ± 0.71, 3.75 ± 0.43, and 3.70 ± 0.53, respectively. Data revealed that nurses' career plateauing accounted for 34% and 18% of the variance of their job satisfaction and promotability, respectively. CONCLUSION: Career plateauing is a significant determinant of nurses' job satisfaction and promotability.

Decreased Left Atrial Reservoir Strain Is Associated with Adverse Outcomes in Restrictive Cardiomyopathy.

Background: Restrictive cardiomyopathy (RCM) places patients at high risk for adverse events. In this study, we aim to evaluate the association between left atrial function and time to adverse events such as all-cause mortality and cardiovascular hospitalizations related to RCM. Material and Methods: In this single-center study, ninety-eight patients with a clinical diagnosis of RCM were recruited from our registry: 30 women (31%); age (mean ± standard deviation) 61 ± 13 years. These patients underwent cardiac magnetic resonance (CMR) imaging from May 2007 to September 2015. Left atrial (LA) function (reservoir, contractile, and conduit strain), LA diameter and area, and left ventricular function (global longitudinal strain, ejection fraction), and volume were quantified, and the presence of late gadolinium enhancement was visually assessed. The cutoff value of the LA reservoir strain was selected based on tertile. An adjusted Cox proportional regression analysis was used to assess time to adverse outcomes with a median follow up of 49 months. Results: In our cohort, all-cause mortality was 36% (35/98). Composite events (all-cause mortality and cardiovascular hospitalizations) occurred in 56% of patients (55/98). All-cause mortality and composite events were significantly associated with a decreased LA reservoir strain (adjusted hazard ratio (aHR) = 0.957, p = 0.002 and aHR = 0.969, p = 0.008) using a stepwise elimination of imaging variables, demographics, and comorbidities. All-cause mortality and composite events were six and almost four times higher, respectively, in patients with the LA reservoir strain <15% (aHR = 5.971, p = 0.005, and HR = 4.252, p = 0.001) compared to patients with the LA reservoir strain >34%. Survival was significantly reduced in patients with an LA reservoir strain <15% (p = 0.008). Conclusions: The decreased LA reservoir strain is independently associated with time to adverse events in patients with RCM.

Myocardial Strain Evaluation with Cardiovascular MRI: Physics, Principles, and Clinical Applications.

Myocardial strain is a measure of myocardial deformation, which is a more sensitive imaging biomarker of myocardial disease than the commonly used ventricular ejection fraction. Although myocardial strain is commonly evaluated by using speckle-tracking echocardiography, cardiovascular MRI (CMR) is increasingly performed for this purpose. The most common CMR technique is feature tracking (FT), which involves postprocessing of routinely acquired cine MR images. Other CMR strain techniques require dedicated sequences, including myocardial tagging, strain-encoded imaging, displacement encoding with stimulated echoes, and tissue phase mapping. The complex systolic motion of the heart can be resolved into longitudinal strain, circumferential strain, radial strain, and torsion. Myocardial strain metrics include strain, strain rate, displacement, velocity, torsion, and torsion rate. Wide variability exists in the reference ranges for strain dependent on the imaging technique, analysis software, operator, patient demographics, and hemodynamic factors. In anticancer therapy cardiotoxicity, CMR myocardial strain can help identify left ventricular dysfunction before the decline of ejection fraction. CMR myocardial strain is also valuable for identifying patients with left ventricle dyssynchrony who will benefit from cardiac resynchronization therapy. CMR myocardial strain is also useful in ischemic heart disease, cardiomyopathies, pulmonary hypertension, and congenital heart disease. The authors review the physics, principles, and clinical applications of CMR strain techniques. Online supplemental material is available for this article. ©RSNA, 2022.

Multiple two-dimensional active shape model framework for right ventricular segmentation.

Segmentation of the right ventricle (RV) in MRI short axis images is very challenging due to its complex shape and various appearance among the different subjects and cross-sections. Active shape models (ASM) have shown potential for segmenting the complex structures, including the RV, through two formulations: two- and three-dimensional modeling with a reported trade-off between accuracy and complexity of each formulation. In this work, we propose a new framework for modeling the RV surface using multiple 2D contours, where information from multiple cross-sectional images are incorporated into the same model. The proposed method was tested using cardiac MRI images from 56 human subjects. Compared to a golden reference of manually delineated RV contours, the proposed method resulted in significantly lower error than (almost one half) that of the conventional 2D ASM especially at the apical slices. The mean absolute distance of the proposed method was 2.9 ± 2 mm while the conventional 2D ASM resulted in an error of 6.6 ± 4.5 mm. In addition, the computation time of the proposed method was 5 s compared to 4 ± 1 min previously reported for the 3D ASM formulation.

Myocardial Contractility Pattern Characterization in Radiation-Induced Cardiotoxicity Using Magnetic Resonance Imaging: A Pilot Study with ContractiX.

Radiation therapy (RT) plays an integral role in treating thoracic cancers, despite the risk of radiation-induced cardiotoxicity. We hypothesize that our newly developed magnetic resonance imaging (MRI)-based contractility index (ContractiX) is a sensitive marker for early detection of RT-induced cardiotoxicity in a preclinical rat model of thoracic cancer RT. Adult salt-sensitive rats received image-guided heart RT and were imaged with MRI at 8 weeks and 10 weeks post-RT or sham. The MRI exam included cine and tagging sequences to measure left-ventricular ejection fraction (LVEF), mass, myocardial strain, and ContractiX. Furthermore, ventricular torsion, diastolic strain rate, and mechanical dyssynchrony were measured. Statistical analyses were performed between the sham, 8 weeks post-RT, and 10 weeks post-RT MRI parameters. The results showed that both LVEF and myocardial mass increased post-RT. Peak systolic strain and ContractiX significantly decreased post-RT, with a more relative reduction in ContractiX compared to strain. ContractiX showed an inverse nonlinear relationship with LVEF and continuously decreased with time post-RT. While early diastolic strain rate and mechanical dyssynchrony significantly changed post-RT, ventricular torsion changes were not significant post-RT. In conclusion, ContractiX measured via non-contrast MRI is a sensitive early marker for the detection of subclinical cardiac dysfunction post-RT, and it is superior to other MRI cardiac measures.

Diastolic Cardiac Function by MRI-Imaging Capabilities and Clinical Applications.

Most cardiac studies focus on evaluating left ventricular (LV) systolic function. However, the assessment of diastolic cardiac function is becoming more appreciated, especially with the increasing prevalence of pathologies associated with diastolic dysfunction like heart failure with preserved ejection fraction (HFpEF). Diastolic dysfunction is an indication of abnormal mechanical properties of the myocardium, characterized by slow or delayed myocardial relaxation, abnormal LV distensibility, and/or impaired LV filling. Diastolic dysfunction has been shown to be associated with age and other cardiovascular risk factors such as hypertension and diabetes mellitus. In this context, cardiac magnetic resonance imaging (MRI) has the capability for differentiating between normal and abnormal myocardial relaxation patterns, and therefore offers the prospect of early detection of diastolic dysfunction. Although diastolic cardiac function can be assessed from the ratio between early and atrial filling peaks (E/A ratio), measuring different parameters of heart contractility during diastole allows for evaluating spatial and temporal patterns of cardiac function with the potential for illustrating subtle changes related to age, gender, or other differences among different patient populations. In this article, we review different MRI techniques for evaluating diastolic function along with clinical applications and findings in different heart diseases.

Diagnostic performance of kidney injury molecule-1 for detection of abnormal urinary albumin-to-creatinine ratio in type 2 diabetes mellitus.

In this study, we aimed to investigate whether serum and urinary levels of kidney injury molecule 1 (KIM-1) are increased in type 2 diabetes mellitus (DM) patients with albuminuria. While the correlation of urinary KIM-1 with renal impairment has been well established, the association with serum KIM-1 has not yet been so well documented. The present pilot study included Egyptian patients with type 2 diabetes (T2D): A total of 84 patients with T2D (age 49-64 years; 20 men) were included in the analysis of the present study. They were divided into two groups according to Alb/Cr ratio: the first group included 32 patients (38.1%) with abnormal Alb/Cr ratio (38.6 mg/g·Cr), and the second group included 52 patients with normal Alb/Cr ratio (17.9 mg/g·Cr). Serum and urinary KIM-1 were measured using enzyme-linked immunoassays. There was a significant difference between both serum and urine KIM-1 and Alb/Cr ratio. Patients with abnormal Alb/Cr ratio had significantly higher serum and urinary KIM-1. These results yielded sensitivity (75.0%) and specificity (96.2%) regarding serum KIM-1 with a cut-off point of 37.5 pg/mL, and sensitivity (93.8%) and specificity (88.5%) regarding urinary KIM1 with a cut-off point of 32.00 ng/g.Cr. Serum KIM-1 and urinary KIM-1 were significantly correlated with eGFR and Alb/Cr ratio. In this pilot study, we found that urinary, serum, and urinary levels of KIM-1 are associated with significant impairments in renal function among diabetic patients. Our results also showed that serum and urine KIM-1 can be used as potential biomarkers for diabetic kidney disease.

Improving MR Image Quality in Patients with Metallic Implants.

The number of implanted devices such as orthopedic hardware and cardiac implantable devices continues to increase with an increase in the age of the patient population, as well as an increase in the number of indications for specific devices. Many patients with these devices have or will develop clinical conditions that are best depicted at MRI. However, implanted devices containing paramagnetic or ferromagnetic substances can cause significant artifact, which could limit the diagnostic capability of this modality. Performing imaging with MRI when an implant is present may be challenging, and there are numerous techniques the radiologist and technologist can use to help minimize artifacts related to implants. First, knowledge of the presence of an implant before patient arrival is critical to ensure safety of the patient when the device is subjected to a strong magnetic field. Once safety is ensured, the examination should be performed with the MRI system that is expected to provide the best image quality. The selection of the MRI system includes multiple considerations such as the effects of field strength and availability of specific sequences, which can reduce metal artifact. Appropriate patient positioning, attention to MRI parameters (including bandwidth, voxel size, and echo), and appropriate selection of sequences (those with less metal artifact and advanced metal reduction sequences) are critical to improve image quality. Patients with implants can be successfully imaged with MRI with appropriate planning and understanding of how to minimize artifacts. This improves image quality and the diagnostic confidence of the radiologist. ©RSNA, 2021.