Micro/nanomotors represent a burgeoning field of research featuring small devices capable of autonomous movement in liquid environments through catalytic reactions and/or external stimuli. This ...review delves into recent advancements in light-driven semiconductor-based micro/nanomotors (LDSM), focusing on optimized syntheses, enhanced motion mechanisms, and emerging applications in the environmental and biomedical domains. The survey commences with a theoretical introduction to micromotors and their propulsion mechanisms, followed by an exploration of commonly studied LDSM, emphasizing their advantages. Critical properties affecting propulsion, such as surface features, morphology, and size, are presented alongside discussions on external conditions related to light sources and intensity, which are crucial for optimizing the propulsion speed. Each property is accompanied by a theoretical background and conclusions drawn up to 2018. The review further investigates recent adaptations of LDSM, uncovering underlying mechanisms and associated benefits. A brief discussion is included on potential synergistic effects between different external conditions, aiming to enhance efficiency-a relatively underexplored topic. In conclusion, the review outlines emerging applications in biomedicine and environmental monitoring/remediation resulting from recent LDSM research, highlighting the growing significance of this field. The comprehensive exploration of LDSM advancements provides valuable insights for researchers and practitioners seeking to leverage these innovative micro/nanomotors in diverse applications.
This JACC Scientific Expert Panel provides consensus recommendations for an update of the cardiovascular magnetic resonance (CMR) diagnostic criteria for myocardial inflammation in patients with ...suspected acute or active myocardial inflammation (Lake Louise Criteria) that include options to use parametric mapping techniques. While each parameter may indicate myocardial inflammation, the authors propose that CMR provides strong evidence for myocardial inflammation, with increasing specificity, if the CMR scan demonstrates the combination of myocardial edema with other CMR markers of inflammatory myocardial injury. This is based on at least one T2-based criterion (global or regional increase of myocardial T2 relaxation time or an increased signal intensity in T2-weighted CMR images), with at least one T1-based criterion (increased myocardial T1, extracellular volume, or late gadolinium enhancement). While having both a positive T2-based marker and a T1-based marker will increase specificity for diagnosing acute myocardial inflammation, having only one (i.e., T2-based OR T1-based) marker may still support a diagnosis of acute myocardial inflammation in an appropriate clinical scenario, albeit with less specificity. The update is expected to improve the diagnostic accuracy of CMR further in detecting myocardial inflammation.
Myocardial fibrosis, either focal or diffuse, is a common feature of many cardiac diseases and is associated with a poor prognosis for major adverse cardiovascular events. Although histological ...analysis remains the gold standard for confirming the presence of myocardial fibrosis, endomyocardial biopsy is invasive, has sampling errors, and is not practical in the routine clinical setting. Cardiac imaging modalities offer noninvasive surrogate biomarkers not only for fibrosis but also for myocardial edema and infiltration to varying degrees, and have important roles in the diagnosis and management of cardiac diseases. This review summarizes important pathophysiological features in the development of commonly encountered cardiac diseases, and the principles, advantages, and disadvantages of various cardiac imaging modalities (echocardiography, single-photon emission computer tomography, positron emission tomography, multidetector computer tomography, and cardiac magnetic resonance) for myocardial tissue characterization, with an emphasis on imaging focal and diffuse myocardial fibrosis.
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•Tissue composition changes such as fibrosis, edema, or infiltration are frequent features in myocardial diseases.•Cardiac imaging modalities offer the ability to characterize myocardial tissue to varying extent.•Cardiovascular magnetic resonance offers comprehensive myocardial tissue characterization by providing various diagnostic and prognostic imaging biomarkers.•Advanced cardiac imaging is expected to become an integral part in risk stratification and personalized medicine.
T1 mapping allows direct in-vivo quantitation of microscopic changes in the myocardium, providing new diagnostic insights into cardiac disease. Existing methods require long breath holds that are ...demanding for many cardiac patients. In this work we propose and validate a novel, clinically applicable, pulse sequence for myocardial T1-mapping that is compatible with typical limits for end-expiration breath-holding in patients.
The Shortened MOdified Look-Locker Inversion recovery (ShMOLLI) method uses sequential inversion recovery measurements within a single short breath-hold. Full recovery of the longitudinal magnetisation between sequential inversion pulses is not achieved, but conditional interpretation of samples for reconstruction of T1-maps is used to yield accurate measurements, and this algorithm is implemented directly on the scanner. We performed computer simulations for 100 ms<T1 < 2.7 s and heart rates 40-100 bpm followed by phantom validation at 1.5T and 3T. In-vivo myocardial T1-mapping using this method and the previous gold-standard (MOLLI) was performed in 10 healthy volunteers at 1.5T and 3T, 4 volunteers with contrast injection at 1.5T, and 4 patients with recent myocardial infarction (MI) at 3T.
We found good agreement between the average ShMOLLI and MOLLI estimates for T1 < 1200 ms. In contrast to the original method, ShMOLLI showed no dependence on heart rates for long T1 values, with estimates characterized by a constant 4% underestimation for T1 = 800-2700 ms. In-vivo, ShMOLLI measurements required 9.0 ± 1.1 s (MOLLI = 17.6 ± 2.9 s). Average healthy myocardial T1 s by ShMOLLI at 1.5T were 966 ± 48 ms (mean ± SD) and 1166 ± 60 ms at 3T. In MI patients, the T1 in unaffected myocardium (1216 ± 42 ms) was similar to controls at 3T. Ischemically injured myocardium showed increased T1 = 1432 ± 33 ms (p < 0.001). The difference between MI and remote myocardium was estimated 15% larger by ShMOLLI than MOLLI (p < 0.04) which suffers from heart rate dependencies for long T1. The in-vivo variability within ShMOLLI T1-maps was only 14% (1.5T) or 18% (3T) higher than the MOLLI maps, but the MOLLI acquisitions were twice longer than ShMOLLI acquisitions.
ShMOLLI is an efficient method that generates immediate, high-resolution myocardial T1-maps in a short breath-hold with high precision. This technique provides a valuable clinically applicable tool for myocardial tissue characterisation.
Parametric mapping techniques provide a non-invasive tool for quantifying tissue alterations in myocardial disease in those eligible for cardiovascular magnetic resonance (CMR). Parametric mapping ...with CMR now permits the routine spatial visualization and quantification of changes in myocardial composition based on changes in T1, T2, and T2*(star) relaxation times and extracellular volume (ECV). These changes include specific disease pathways related to mainly intracellular disturbances of the cardiomyocyte (e.g., iron overload, or glycosphingolipid accumulation in Anderson-Fabry disease); extracellular disturbances in the myocardial interstitium (e.g., myocardial fibrosis or cardiac amyloidosis from accumulation of collagen or amyloid proteins, respectively); or both (myocardial edema with increased intracellular and/or extracellular water). Parametric mapping promises improvements in patient care through advances in quantitative diagnostics, inter- and intra-patient comparability, and relatedly improvements in treatment. There is a multitude of technical approaches and potential applications. This document provides a summary of the existing evidence for the clinical value of parametric mapping in the heart as of mid 2017, and gives recommendations for practical use in different clinical scenarios for scientists, clinicians, and CMR manufacturers.
Objectives This study sought to explore the potential role of noncontrast myocardial T1 mapping for detection of cardiac involvement in patients with primary amyloid light-chain (AL) amyloidosis. ...Background Cardiac involvement carries a poor prognosis in systemic AL amyloidosis. Late gadolinium enhancement (LGE) cardiac magnetic resonance (CMR) is useful for the detection of cardiac amyloid, but characteristic LGE patterns do not always occur or they appear late in the disease. Noncontrast characterization of amyloidotic myocardium with T1 mapping may improve disease detection. Furthermore, quantitative assessment of myocardial amyloid load would be of great value. Methods Fifty-three AL amyloidosis patients (14 with no cardiac involvement, 11 with possible involvement, and 28 with definite cardiac involvement based on standard biomarker and echocardiographic criteria) underwent CMR (1.5-T) including noncontrast T1 mapping (shortened modified look-locker inversion recovery ShMOLLI sequence) and LGE imaging. These were compared with 36 healthy volunteers and 17 patients with aortic stenosis and a comparable degree of left ventricular hypertrophy as the cardiac amyloid patients. Results Myocardial T1 was significantly elevated in cardiac AL amyloidosis patients (1,140 ± 61 ms) compared to normal subjects (958 ± 20 ms, p < 0.001) and patients with aortic stenosis (979 ± 51 ms, p < 0.001). Myocardial T1 was increased in AL amyloid even when cardiac involvement was uncertain (1,048 ± 48 ms) or thought absent (1,009 ± 31 ms). A noncontrast myocardial T1 cutoff of 1,020 ms yielded 92% accuracy for identifying amyloid patients with possible or definite cardiac involvement. In the AL amyloidosis cohort, there were significant correlations between myocardial T1 time and indices of systolic and diastolic dysfunction. Conclusions Noncontrast T1 mapping has high diagnostic accuracy for detecting cardiac AL amyloidosis, correlates well with markers of systolic and diastolic dysfunction, and is potentially more sensitive for detecting early disease than LGE imaging. Elevated myocardial T1 may represent a direct marker of cardiac amyloid load. Further studies are needed to assess the prognostic significance of T1 elevation.
T2w-CMR is used widely to assess myocardial edema. Quantitative T1-mapping is also sensitive to changes in free water content. We hypothesized that T1-mapping would have a higher diagnostic ...performance in detecting acute edema than dark-blood and bright-blood T2w-CMR.
We investigated 21 controls (55 ± 13 years) and 21 patients (61 ± 10 years) with Takotsubo cardiomyopathy or acute regional myocardial edema without infarction. CMR performed within 7 days included cine, T1-mapping using ShMOLLI, dark-blood T2-STIR, bright-blood ACUT2E and LGE imaging. We analyzed wall motion, myocardial T1 values and T2 signal intensity (SI) ratio relative to both skeletal muscle and remote myocardium.
All patients had acute cardiac symptoms, increased Troponin I (0.15-36.80 ug/L) and acute wall motion abnormalities but no LGE. T1 was increased in patient segments with abnormal and normal wall motion compared to controls (1113 ± 94 ms, 1029 ± 59 ms and 944 ± 17 ms, respectively; p < 0.001). T2 SI ratio using STIR and ACUT2E was also increased in patient segments with abnormal and normal wall motion compared to controls (all p < 0.02). Receiver operator characteristics analysis showed that T1-mapping had a significantly larger area-under-the-curve (AUC = 0.94) compared to T2-weighted methods, whether the reference ROI was skeletal muscle or remote myocardium (AUC = 0.58-0.89; p < 0.03). A T1 value of greater than 990 ms most optimally differentiated segments affected by edema from normal segments at 1.5 T, with a sensitivity and specificity of 92 %.
Non-contrast T1-mapping using ShMOLLI is a novel method for objectively detecting myocardial edema with a high diagnostic performance. T1-mapping may serve as a complementary technique to T2-weighted imaging for assessing myocardial edema in ischemic and non-ischemic heart disease, such as quantifying area-at-risk and diagnosing myocarditis.
Fluid-feeding herbivores directly affect host plants through sap consumption. Moreover, they establish mutualistic relationships with ants, which might generate additional reproductive costs related ...to pollinator repellence. Here we studied the drivers of variation in the outcomes of these interactions from the perspective of
Psittacanthus robustus
, a hummingbird-pollinated mistletoe. We hypothesized that associations between fluid-feeding insects and ants should indirectly decrease mistletoe reproduction by repelling pollinators, and directly by reducing seed size, germination, and establishment of plants presenting denser herbivore aggregations. First, we manipulated the presence of the ant
Camponotus rufipes
on mistletoe inflorescences to assess their effects on visitation behavior of pollinators. We correlated fruit production and fruit and seed size to abundance of fluid-feeding insects on plants. Moreover, we conducted a field experiment assessing the effects of aggregation size of fluid-feeding herbivores on seed germination and seedling establishment. Ant presence on inflorescences did not affect the visitation rates of the main pollinator, the hummingbird
Eupetomena macroura
. Abundance of fluid-feeding herbivores did not explain variation in fruit crop size. However, we observed a significant reduction in seed size in those plants hosting larger aggregations of fluid-feeding herbivores. The reduction in seed size did not translate into a significant decrease in seed germination nor a decrease in seedling establishment. Our results dispute previous studies highlighting negative indirect effects on plant–pollinator interactions mediated by the presence of ant–trophobiont mutualisms. Likewise, our study underscores the need of assessing fluid-feeding herbivore effects on crucial stages of the host plant life cycle to clarify fitness consequences of multitrophic interactions.
Current cardiovascular magnetic resonance (CMR) methods, such as late gadolinium enhancement (LGE) and oedema imaging (T2W) used to depict myocardial ischemia, have limitations. Novel quantitative ...T1-mapping techniques have the potential to further characterize the components of ischemic injury. In patients with myocardial infarction (MI) we sought to investigate whether state-of the art pre-contrast T1-mapping (1) detects acute myocardial injury, (2) allows for quantification of the severity of damage when compared to standard techniques such as LGE and T2W, and (3) has the ability to predict long term functional recovery.
3T CMR including T2W, T1-mapping and LGE was performed in 41 patients of these, 78% were ST elevation MI (STEMI) with acute MI at 12-48 hour after chest pain onset and at 6 months (6M). Patients with STEMI underwent primary PCI prior to CMR. Assessment of acute regional wall motion abnormalities, acute segmental damaged fraction by T2W and LGE and mean segmental T1 values was performed on matching short axis slices. LGE and improvement in regional wall motion at 6M were also obtained.
We found that the variability of T1 measurements was significantly lower compared to T2W and that, while the diagnostic performance of acute T1-mapping for detecting myocardial injury was at least as good as that of T2W-CMR in STEMI patients, it was superior to T2W imaging in NSTEMI. There was a significant relationship between the segmental damaged fraction assessed by either by LGE or T2W, and mean segmental T1 values (P < 0.01). The index of salvaged myocardium derived by acute T1-mapping and 6M LGE was not different to the one derived from T2W (P = 0.88). Furthermore, the likelihood of improvement of segmental function at 6M decreased progressively as acute T1 values increased (P < 0.0004).
In acute MI, pre-contrast T1-mapping allows assessment of the extent of myocardial damage. T1-mapping might become an important complementary technique to LGE and T2W for identification of reversible myocardial injury and prediction of functional recovery in acute MI.
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