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Pulmonary air leaks are amongst the most common complications in lung surgery. Lung sealants are applied to the organ surface and need to synchronously stretch with the visceral pleura, the layer of tissue which encompasses the lung parenchymal tissue. These adhesives are commonly tested on pig and rat lungs, but applied to human lungs. However, the unknown mechanics of human lung visceral pleura undermines the clinical translatability of such animal-tested sealants and the absence of how pig and rat lung visceral pleura compare to human tissues is necessary to address. Here we quantify the biaxial planar tensile mechanics of visceral pleura from healthy transplant-eligible and smoker human lungs for the first time, and further compare the material behaviors to pig and rat lung visceral pleura. Initial and final stiffness moduli, maximum stress, low-to-high strain transition, and stress relaxation are analyzed and compared between and within groups, further considering regional and directional dependencies. Visceral pleura tissue from all species behave isotropically, and pig and human visceral pleura exhibits regional heterogeneity (i.e. upper versus lower lobe differences). We find that pig visceral pleura exhibits similar initial stiffness moduli and regional trends compared to human visceral pleura, suggesting pig tissue may serve as a viable animal model candidate for lung sealant testing. The outcomes and mechanical characterization of these scarce tissues enables future development of biomimetic lung sealants for improved surgical applications. STATEMENT OF SIGNIFICANCE: Surgical lung sealants must synchronously deform with the underlying tissue and with each breath to minimize post-operative air leaks, which remain the most frequent complications of pulmonary intervention. These adhesives are often tested on pig and rat lungs, but applied to humans; however, the material properties of human lung visceral pleura were previously unexplored. Here, for the first time, the mechanics of human visceral pleura tissue are investigated, further contrasting rarely acquired donated lungs from healthy and smoking individuals, and additionally, comparing biaxial planar material characterizations to animal models often employed for pulmonary sealant development. This fundamental material characterization addresses key hindrances in the advancement of biomimetic sealants and evaluates the translatability of animal model experiments for clinical applications.

OBJECTIVE: Cardiac magnetic resonance (CMR) is a diagnostic tool that provides precise and reproducible information about cardiac structure, function, and tissue characterization, aiding in the monitoring of chemotherapy response in patients with light-chain cardiac amyloidosis (AL-CA). This study aimed to evaluate the feasibility of CMR in monitoring responses to chemotherapy in patients with AL-CA. MATERIALS AND METHODS: In this prospective study, we enrolled 111 patients with AL-CA (50.5% male; median age, 54 [interquartile range, 49-63] years). Patients underwent longitudinal monitoring using biomarkers and CMR imaging. At follow-up after chemotherapy, patients were categorized into superior and inferior response groups based on their hematological and cardiac laboratory responses to chemotherapy. Changes in CMR findings across therapies and differences between response groups were analyzed. RESULTS: Following chemotherapy (before vs. after), there were significant increases in myocardial T2 (43.6 ± 3.5 ms vs. 44.6 ± 4.1 ms; P = 0.008), recovery in right ventricular (RV) longitudinal strain (median of -9.6% vs. -11.7%; P = 0.031), and decrease in RV extracellular volume fraction (ECV) (median of 53.9% vs. 51.6%; P = 0.048). These changes were more pronounced in the superior-response group. Patients with superior cardiac laboratory response showed significantly greater reductions in RV ECV (-2.9% [interquartile range, -8.7%-1.1%] vs. 1.7% [-5.5%-7.1%]; P = 0.017) and left ventricular ECV (-2.0% [-6.0%-1.3%] vs. 2.0% [-3.0%-5.0%]; P = 0.01) compared with those with inferior response. CONCLUSION: Cardiac amyloid deposition can regress following chemotherapy in patients with AL-CA, particularly showing more prominent regression, possibly earlier, in the RV. CMR emerges as an effective tool for monitoring associated tissue characteristics and ventricular functional recovery in patients with AL-CA undergoing chemotherapy, thereby supporting its utility in treatment response assessment.

Medical techniques for scanning the brain enable imaging of its structure or function of the brain. There is growing interest in using quantum light for tissue scanning. A precise investigation of this quantum mechanical phenomenon can lead to new medical diagnostics and brain imaging techniques. In this study, we employed quantum photon pair's, created by spontaneous parametric down-conversion. The technique involved preparing pairs of photons in maximally-entangled Bell states in the polarization degree of freedom. One part of the entangled photons was focused on rat brain tissue. The state of the photons passing through the brain was measured. We compared the preservation of the photon pairs' quantum correlation in polarization via Bell parameter measurement of the transmitted entangled photons. Our results show a distinct difference in the entanglement preservation among different regions of the rat brain. The cortex tissue meaningfully preserved the photons' correlation to a high degree despite the scattering effect , while the inner part, like the amygdala, degraded the entanglement and the Bell parameter declined to 1.31. The gradual decrease of the Bell parameter, indicating the decoherence of entangled photons in the tissue, can serve as a proper criterion to describe the characteristics of biological media. This study can be a major step toward a modern imaging method and brain mapping in the future. [ABSTRACT FROM AUTHOR]

Pulmonary air leaks are amongst the most common complications in lung surgery. Lung sealants are applied to the organ surface and need to synchronously stretch with the visceral pleura, the layer of tissue which encompasses the lung parenchymal tissue. These adhesives are commonly tested on pig and rat lungs, but applied to human lungs. However, the unknown mechanics of human lung visceral pleura undermines the clinical translatability of such animal-tested sealants and the absence of how pig and rat lung visceral pleura compare to human tissues is necessary to address. Here we quantify the biaxial planar tensile mechanics of visceral pleura from healthy transplant-eligible and smoker human lungs for the first time, and further compare the material behaviors to pig and rat lung visceral pleura. Initial and final stiffness moduli, maximum stress, low-to-high strain transition, and stress relaxation are analyzed and compared between and within groups, further considering regional and directional dependencies. Visceral pleura tissue from all species behave isotropically, and pig and human visceral pleura exhibits regional heterogeneity (i.e. upper versus lower lobe differences). We find that pig visceral pleura exhibits similar initial stiffness moduli and regional trends compared to human visceral pleura, suggesting pig tissue may serve as a viable animal model candidate for lung sealant testing. The outcomes and mechanical characterization of these scarce tissues enables future development of biomimetic lung sealants for improved surgical applications. Surgical lung sealants must synchronously deform with the underlying tissue and with each breath to minimize post-operative air leaks, which remain the most frequent complications of pulmonary intervention. These adhesives are often tested on pig and rat lungs, but applied to humans; however, the material properties of human lung visceral pleura were previously unexplored. Here, for the first time, the mechanics of human visceral pleura tissue are investigated, further contrasting rarely acquired donated lungs from healthy and smoking individuals, and additionally, comparing biaxial planar material characterizations to animal models often employed for pulmonary sealant development. This fundamental material characterization addresses key hindrances in the advancement of biomimetic sealants and evaluates the translatability of animal model experiments for clinical applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract A Mueller matrix covers all the polarization information of the measured sample, however the combination of its 16 elements is sometimes not intuitive enough to describe and identify the key characteristics of polarization changes. Within the Poincaré sphere system, this study achieves a spatial representation of the Mueller matrix: the Global-Polarization Stokes Ellipsoid (GPSE). With the help of Monte Carlo simulations combined with anisotropic tissue models, three basic characteristic parameters of GPSE are proposed and explained, where the V parameter represents polarization maintenance ability, and the E and D † parameters represent the degree of anisotropy. Furthermore, based on GPSE system, a dynamic analysis of skeletal muscle dehydration process demonstrates the monitoring effect of GPSE from an application perspective, while confirming its robustness and accuracy.

A Mueller matrix covers all the polarization information of the measured sample, however the combination of its 16 elements is sometimes not intuitive enough to describe and identify the key characteristics of polarization changes. Within the Poincaré sphere system, this study achieves a spatial representation of the Mueller matrix: the Global-Polarization Stokes Ellipsoid (GPSE). With the help of Monte Carlo simulations combined with anisotropic tissue models, three basic characteristic parameters of GPSE are proposed and explained, where the V parameter represents polarization maintenance ability, and the E and D† parameters represent the degree of anisotropy. Furthermore, based on GPSE system, a dynamic analysis of skeletal muscle dehydration process demonstrates the monitoring effect of GPSE from an application perspective, while confirming its robustness and accuracy. [ABSTRACT FROM AUTHOR]

Acoustic droplet vaporization (ADV) offers a dynamic approach for generating bubbles on demand, presenting new possibilities in biomedical applications. Although ADV has been investigated in various biomedical applications, its potential in tissue characterization remains unexplored. Here, we investigated the effects of surrounding media on the radial dynamics and acoustic emissions of ADV bubbles using theoretical and experimental methodologies. For theoretical studies, bubble dynamics were combined with the Kelvin-Voigt material constitutive model, accounting for viscoelasticity of the media. The radial dynamics and acoustic emissions of the ADV-bubbles were recorded via ultra-high-speed microscopy and passive cavitation detection, respectively. Perfluoropentane phase-shift droplets were embedded in tissue-mimicking hydrogels of varying fibrin concentrations, representing different elastic moduli. Radial dynamics and the acoustic emissions, both temporal and spectral, of the ADV-bubbles depended significantly on fibrin elastic modulus. For example, an increase in fibrin elastic modulus from ≈0.2 kPa to ≈6 kPa reduced the maximum expansion radius of the ADV-bubbles by 50%. A similar increase in the elastic modulus significantly impacted both linear (e.g., fundamental) and nonlinear (e.g., subharmonic) acoustic responses of the ADV-bubbles, by up to 10 dB. The sensitivity of ADV to the surrounding media was dependent on acoustic parameters such as driving pressure and the droplets concentration. Further analysis of the acoustic emissions revealed distinct ADV signal characteristics, which were significantly influenced by the surrounding media.

PURPOSE: To develop a free-breathing, non-electrocardiogram technique for simultaneous myocardial T1 , T2 , T2 *, and fat-fraction (FF) mapping in a single scan. METHODS: The MR Multitasking framework is adapted to quantify T1 , T2 , T2 *, and FF simultaneously. A variable TR scheme is developed to preserve temporal resolution and imaging efficiency. The underlying high-dimensional image is modeled as a low-rank tensor, which allows accelerated acquisition and efficient reconstruction. The accuracy and/or repeatability of the technique were evaluated on static and motion phantoms, 12 healthy volunteers, and 3 patients by comparing to the reference techniques. RESULTS: In static and motion phantoms, T1 /T2 /T2 */FF measurements showed substantial consistency (R > 0.98) and excellent agreement (intraclass correlation coefficient > 0.93) with reference measurements. In human subjects, the proposed technique yielded repeatable T1 , T2 , T2 *, and FF measurements that agreed with those from references. CONCLUSIONS: The proposed free-breathing, non-electrocardiogram, motion-resolved Multitasking technique allows simultaneous quantification of myocardial T1 , T2 , T2 *, and FF in a single 2.5-min scan.

Aims To characterize acute lesions during cardiac magnetic resonance (CMR)-guided radiofrequency (RF) ablation of cavo-tricuspid isthmus (CTI)-dependent atrial flutter by combining T2-weighted imaging (T2WI), T1 mapping, first-pass perfusion, and late gadolinium enhancement (LGE) imaging. CMR-guided catheter ablation offers a unique opportunity to investigate acute ablation lesions. Until present, studies only used T2WI and LGE CMR to assess acute lesions. Methods and results Fifteen patients with CTI-dependent atrial flutter scheduled for CMR-guided RF ablation were prospectively enrolled. Directly after achieving bidirectional block of the CTI line, CMR imaging was performed using: T2WI (n = 15), T1 mapping (n = 10), first-pass perfusion (n = 12), and LGE (n = 12) imaging. In case of acute reconnection, additional RF ablation was performed. In all patients, T2WI demonstrated oedema in the ablation region. Right atrial T1 mapping was feasible and could be analysed with a high inter-observer agreement (r = 0.931, ICC 0.921). The increase in T1 values post-ablation was significantly lower in regions showing acute reconnection compared with regions without reconnection [37 ± 90 ms vs. 115 ± 69 ms (P = 0.014), and 3.9 ± 9.0% vs. 11.1 ± 6.8% (P = 0.022)]. Perfusion defects were present in 12/12 patients. The LGE images demonstrated hyper-enhancement with a central area of hypo-enhancement in 12/12 patients. Conclusion Tissue characterization of acute lesions during CMR-guided CTI-dependent atrial flutter ablation demonstrates oedema, perfusion defects, and necrosis with a core of microvascular damage. Right atrial T1 mapping is feasible, and may identify regions of acute reconnection that require additional RF ablation. [ABSTRACT FROM AUTHOR]

Despite recent improvements in medical imaging, the final diagnosis and biopathologic characterization of breast cancers currently still requires biopsies. Ultrasound is commonly used for clinical examination of breast masses. B-Mode and shear wave elastography (SWE) are already widely used to detect suspicious masses and differentiate benign lesions from cancers. But additional ultrasound modalities such as backscatter tensor imaging (BTI) could provide relevant biomarkers related to tissue organization. Here we describe a 3-D multiparametric ultrasound approach applied to breast carcinomas in the aims of (i) validating the ability of BTI to reveal the underlying organization of collagen fibers and (ii) assessing the complementarity of SWE and BTI to reveal biopathologic features of diagnostic interest. Three-dimensional SWE and BTI were performed ex vivo on 64 human breast carcinoma samples using a linear ultrasound probe moved by a set of motors. Here we describe a 3-D multiparametric representation of the breast masses and quantitative measurements combining B-mode, SWE and BTI. Our results reveal for the first time that BTI can capture the orientation of the collagen fibers around tumors. BTI was found to be a relevant marker for assessing cancer stages, revealing a more tangent tissue orientation for in situ carcinomas than for invasive cancers. In invasive cases, the combination of BTI and SWE parameters allowed for classification of invasive tumors with respect to their grade with an accuracy of 95.7%. Our results highlight the potential of 3-D multiparametric ultrasound imaging for biopathologic characterization of breast tumors. [ABSTRACT FROM AUTHOR]

Background: Multiparameter characterization using MR fingerprinting (MRF) can quantify multiple relaxation parameters of intervertebral disc (IVD) simultaneously. These parameters may vary by age and sex. Purpose: To investigate age‐ and sex‐related differences in the relaxation parameters of the IVD of the lumbar spine using a multiparameter MRF technique. Study Type: Prospective. Subjects: 17 healthy subjects (8 male; mean age = 34 ± 10 years, range 20–60 years). Field Strength/Sequence: 3D‐MRF sequence for simultaneous acquisition of proton density, T1, T2, and T1ρ maps at 3.0T. Assessment: Global mean T1, T2, and T1ρ of all lumbar IVDs and mean T1, T2, and T1ρ of each individual IVD (L1–L5) were measured. Gray level co‐occurrence matrix was used to quantify textural features (median, contrast, correlation, energy, and homogeneity) from T1, T2, and T1ρ maps. Statistical Tests: Spearman rank correlations (R) evaluated the association between age and T1, T2, and T1ρ of IVD. Mann–Whitney U‐tests evaluated differences between males and females in T1, T2, and T1ρ of IVD. Statistical significance was defined as P‐value <0.05. Results: There was a significant negative correlation between age and global mean values of all IVDs for T1 (R = −0.637), T2 (R = −0.509), and T1ρ (R = −0.726). For individual IVDs, there was a significant negative correlation between age and mean T1 at all IVD segments (R range = −0.530 to −0.708), between age and mean T2 at L2‐L3, L3‐L4, and L4‐L5 (R range = −0.493 to 0.640), and between age and mean T1ρ at all segments except L1‐L2 (R range = −0.632 to −0.763). There were no significant differences between sexes in global mean T1, T2, and T1ρ (P‐value = 0.23–0.76) The texture features with the highest significant correlations with age for all IVDs were global T1ρ mean (R = −0.726), T1 energy (R = −0.681), and T1 contrast (R = 0.709). Conclusion: This study showed that the 3D‐MRF technique has potential to characterize age‐related differences in T1, T2, or T1ρ of IVD in healthy subjects. Level of Evidence: 2 Technical Efficacy: Stage 1 [ABSTRACT FROM AUTHOR]

Objective: The excellent blood and fat suppression of stimulated echo acquisition mode (STEAM) can be combined with saturation recovery single-shot acquisition (SASHA) in a novel STEAM-SASHA sequence for right ventricular (RV) native T1 mapping. Materials and methods: STEAM-SASHA splits magnetization preparation over two cardiac cycles, nulling blood signal and allowing fat signal to decay. Breath-hold T1 mapping was performed in a T1 phantom and twice in 10 volunteers using STEAM-SASHA and a modified Look-Locker sequence at peak systole at 3T. T1 was measured in 3 RV regions, the septum and left ventricle (LV). Results: In phantoms, MOLLI under-estimated while STEAM-SASHA over-estimated T1, on average by 3.0% and 7.0% respectively, although at typical 3T myocardial T1 (T1 > 1200 ms) STEAM-SASHA was more accurate. In volunteers, T1 was higher using STEAM-SASHA than MOLLI in the LV and septum (p = 0.03, p = 0.006, respectively), but lower in RV regions (p > 0.05). Inter-study, inter-observer and intra-observer coefficients of variation in all regions were < 15%. Blood suppression was excellent with STEAM-SASHA and noise floor effects were minimal. Discussion: STEAM-SASHA provides accurate and reproducible T1 in the RV with excellent blood and fat suppression. STEAM-SASHA has potential to provide new insights into pathological changes in the RV in future studies. [ABSTRACT FROM AUTHOR]

Background: Diffusion-weighted imaging (DWI) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) are widely used in the orofacial region. Furthermore, quantitative analyses have proven useful. However, a few reports have described the correlation between DWI-derived parameters and DCE-MRI-derived parameters, and the results have been controversial. Purpose: To evaluate the correlation among parameters obtained by DWI and DCE-MRI and to compare them between benign and malignant lesions. Material and Methods: Fifty orofacial lesions were analysed. The apparent diffusion coefficient (ADC), true diffusion coefficient (D), pseudodiffusion coefficient (D*) and perfusion fraction (f) were estimated by DWI. For DCE-MRI, TK model analysis was performed to estimate physiological parameters, for example, the influx forward volume transfer constant into the extracellular-extravascular space (EES) (Ktrans) and fractional volumes of EES and plasma components (ve and vp). Results: Both ADC and D showed a moderate positive correlation with ve (ρ = 0.640 and 0.645, respectively). Ktrans showed a marginally weak correlation with f (ρ = 0.296), while vp was not correlated with f or D*; therefore, IVIM perfusion-related parameters and TK model perfusion-related parameters were not straightforward. Both D and ve yielded high diagnostic power between benign lesions and malignant tumours with areas under the curve (AUCs) of 0.830 and 0.782, respectively. Conclusion: Both D and ve were reliable parameters that were useful for the differential diagnosis. In addition, the true diffusion coefficient (D) was affected by the fractional volume of EES. [ABSTRACT FROM AUTHOR]

The current research used a method for the quantification of fat content in many types of meat by comparing their X-ray scattering profiles measured practically and simulated profiles from a Monte Carlo simulation code. The measured X-ray scattering profile of each meat sample was compared to Monte Carlo simulated profiles to deduce the fat percentage in each sample. Two peaks were obtained from each profile. The first peak was at a momentum transfer of 1.1 nm−1 (characteristic of fat content) and the second peak was at a momentum transfer of 1.6 nm−1 (characteristic of muscle content). The correlation coefficient and least square error between measured and simulated data were calculated to obtain the percentage of fat in each sample from the best-fitted profiles. Results showed a high correlation coefficient value and low least square error of value (>0.9) and (<0.07), respectively between measured and simulated profiles. The fat content in each sample is plotted against three profile characterization parameters (the ratio of peak intensities, the ratio of area under peaks and the ratio of area under fat peak to total profile area) for measured and Monte Carlo simulated X-ray scattering profiles. Therefore, it was possible to use this Monte Carlo simulation code as a way for precis quantification of fat percentages in some types of meat. [ABSTRACT FROM AUTHOR]

Image-guided and minimally invasive procedures still require confirmation on having reached a target. Intraoperative imaging is not always sufficient or conclusive as it comes with artifacts that can come with a certain amount of ambiguity and inaccurate location information. As an alternative to imaging, we want to explore sounds produced by the biopsy needle tip while advancing and interacting with tissue. In this paper, we show that by analyzing vibroacoustic signals acquired at the proximal end of the needle we are able to differentiate the tissue type. In total, 419 audio samples of 5 tissues were acquired and converted to spectrograms used as input to a convolutional neural network. Using this experimental setup we were able to differentiate the tissue types with an F1 score of 71.64%. Based on these results we were able to demonstrate the feasibility of our approach, as well as the importance of further experiments to ensure that vibroacoustic sounds produced by the needle tip can be a new navigation method.

Abstract Non-invasive quantification of the extracellular volume (ECV) is a method for the evaluation of focal and diffuse myocardial fibrosis, potentially obviating the need for invasive endomyocardial biopsy. While ECV quantification with cardiac magnetic resonance imaging (ECVMRI) is already an established method, ECV quantification with CT (ECVCT) is an attractive alternative to ECVMRI, similarly using the properties of extracellular contrast media for ECV calculation. In contrast to ECVMRI, ECVCT provides a more widely available, cheaper and faster tool for ECV quantification and allows for ECV calculation also in patients with contraindications for MRI. Many studies have already shown a high correlation between ECVCT and ECVMRI and accumulating evidence suggests a prognostic value of ECVCT quantification in various cardiovascular diseases. Adding a late enhancement scan (for dual energy acquisitions) or a non-enhanced and late enhancement scan (for single-energy acquisitions) to a conventional coronary CT angiography scan improves risk stratification, requiring only minor adaptations of the contrast media and data acquisition protocols and adding only little radiation dose to the entire scan. Critical relevance statement This article summarizes the technical principles of myocardial extracellular volume (ECV) quantification with CT, reviews the literature comparing ECVCT with ECVMRI and histopathology, and reviews the prognostic value of myocardial ECV quantification for various cardiovascular disease. Key points • Non-invasive quantification of myocardial fibrosis can be performed with CT. • Myocardial ECV quantification with CT is an alternative in patients non-eligible for MRI. • Myocardial ECV quantification with CT strongly correlates with ECV quantification using MRI. • Myocardial ECV quantification provides incremental prognostic information for various pathologies affecting the heart (e.g., cardiac amyloidosis). Graphical Abstract

Melanoma is a form of malignant skin cancer that exhibits significant inter-tumoral differences in the tumor microenvironment (TME) secondary to genetic mutations. The heterogeneity may be subtle but can complicate the treatment of metastatic melanoma, contributing to a high mortality rate. Therefore, developing an accurate and non-invasive procedure to discriminate microenvironmental heterogeneity to facilitate therapy selection is an important goal. In vivo murine melanoma models that recapitulate human disease using synchronous implanted YUMM 1.7 (Yale University Mouse Melanoma) and YUMMER 1.7 (Yale University Mouse Melanoma Exposed to Radiation) murine melanoma lines were investigated. Mice were treated with antibodies to modulate the immune response and longitudinally scanned with ultrasound (US). US radiofrequency data were processed using the H-scan analysis, attenuation estimation and B-mode processing to extract five US features. The measures were used to compare different TMEs (YUMMER vs. YUMM) and responses to immunomodulatory therapies with CD8 depletion or programmed cell death protein 1 (PD-1) inhibition. Multiparametric analysis produced a combined H-scan parameter, resolving significant differences (i) between untreated YUMMER and YUMM and (ii) between untreated, PD-1-treated and CD8-treated YUMMER. However, more importantly, the B-mode and attenuation measures failed to differentiate YUMMER and YUMM and to monitor treatment responses, indicating that H-scan is required to differentiate subtle differences within the TME. We anticipate that the H-scan analysis could discriminate heterogeneous melanoma metastases and guide diagnosis and treatment selection, potentially reducing the need for invasive biopsies or immunologic procedures. [ABSTRACT FROM AUTHOR]

Background: The prevalence of liver diseases, especially steatosis, requires a more convenient and noninvasive tool for liver diagnosis, which can be a surrogate for the gold standard biopsy. Magnetic resonance (MR) measurement offers potential, however ultrasound (US) has better accessibility than MR. Purpose: This study aims to suggest a multiparametric US approach which demonstrates better quantification and imaging performance than MR imaging‐based proton density fat fraction (MRI‐PDFF) for hepatic steatosis assessment. Methods: We investigated early‐stage steatosis to evaluate our approach. An in vivo (within the living) animal study was performed. Fat inclusions were accumulated in the animal livers by feeding a methionine and choline deficient (MCD) diet for 2 weeks. The animals (n = 19) underwent US and MR imaging, and then their livers were excised for histological staining. From the US, MR, and histology images, fat accumulation levels were measured and compared: multiple US parameters; MRI‐PDFF; histology fat percentages. Seven individual US parameters were extracted using B‐mode measurement, Burr distribution estimation, attenuation estimation, H‐scan analysis, and shear wave elastography. Feature selection was performed, and the selected US features were combined, providing quantification of fat accumulation. The combined parameter was used for visualizing the localized probability of fat accumulation level in the liver; This procedure is known as disease‐specific imaging (DSI). Results: The combined US parameter can sensitively assess fat accumulation levels, which is highly correlated with histology fat percentage (R = 0.93, p‐value < 0.05) and outperforms the correlation between MRI‐PDFF and histology (R = 0.89, p‐value < 0.05). Although the seven individual US parameters showed lower correlation with histology compared to MRI‐PDFF, the multiparametric analysis enabled US to outperform MR. Furthermore, this approach allowed DSI to detect and display gradual increases in fat accumulation. From the imaging output, we measured the color‐highlighted area representing fatty tissues, and the fat fraction obtained from DSI and histology showed strong agreement (R = 0.93, p‐value < 0.05). Conclusions: We demonstrated that fat quantification utilizing a combination of multiple US parameters achieved higher performance than MRI‐PDFF; therefore, our multiparametric analysis successfully combined selected features for hepatic steatosis characterization. We anticipate clinical use of our proposed multiparametric US analysis, which could be beneficial in assessing steatosis in humans. [ABSTRACT FROM AUTHOR]

Late gadolinium enhancement (LGE) MRI is the non‐invasive reference standard for identifying myocardial scar and fibrosis but has limitations, including difficulty delineating subendocardial scar and operator dependence on image quality. The purpose of this work is to assess the feasibility of generating multi‐contrast synthetic LGE images from post‐contrast T1 and T2 maps acquired using magnetic resonance fingerprinting (MRF). Fifteen consecutive patients with a history of prior ischemic cardiomyopathy (12 men; mean age 63 ± 13 years) were prospectively scanned at 1.5 T between Oct 2020 and May 2021 using conventional LGE and MRF after injection of gadolinium contrast. Three classes of synthetic LGE images were derived from MRF post‐contrast T1 and T2 maps: bright‐blood phase‐sensitive inversion recovery (PSIR), black‐ and gray‐blood T2‐prepared PSIR (T2‐PSIR), and a novel "tissue‐optimized" image to enhance differentiation among scar, viable myocardium, and blood. Image quality was assessed on a 1–5 Likert scale by two cardiologists, and contrast was quantified as the mean absolute difference (MAD) in pixel intensities between two tissues, with different methods compared using Kruskal–Wallis with Bonferroni post hoc tests. Per‐patient and per‐segment scar detection rates were evaluated using conventional LGE images as reference. Image quality scores were highest for synthetic PSIR (4.0) and reference images (3.8), followed by synthetic tissue‐optimized (3.3), gray‐blood T2‐PSIR (3.0), and black‐blood T2‐PSIR (2.6). Among synthetic images, PSIR yielded the highest myocardium/scar contrast (MAD = 0.42) but the lowest blood/scar contrast (MAD = 0.05), and vice versa for T2‐PSIR, while tissue‐optimized images achieved a balance among all tissues (myocardium/scar MAD = 0.16, blood/scar MAD = 0.26, myocardium/blood MAD = 0.10). Based on reference mid‐ventricular LGE scans, 13/15 patients had myocardial scar. The per‐patient sensitivity/accuracy for synthetic images were the following: PSIR, 85/87%; black‐blood T2‐PSIR, 62/53%; gray‐blood T2‐PSIR, 100/93%; tissue optimized, 100/93%. Synthetic multi‐contrast LGE images can be generated from post‐contrast MRF data without additional scan time, with initial feasibility shown in ischemic cardiomyopathy patients. [ABSTRACT FROM AUTHOR]

Background: Cardiovascular Magnetic Resonance (CMR) native T1 and T2 mapping serve as robust, contrast-agent-free diagnostic tools, but hardware- and software-specific sources of variability limit the generalizability of data across CMR platforms, consequently limiting the interpretability of patient-specific parametric data. Z-scores are used to describe the relationship of observed values to the mean results as obtained in a sufficiently large normal sample. They have been successfully used to describe the severity of quantifiable abnormalities in medicine, specifically in children and adolescents. The objective of this study was to observe whether z-scores can improve the comparability of T1 and T2 mapping values across CMR scanners, field strengths, and sequences from different vendors in the same participant rather than different participants (as seen in previous studies). Methods: Fifty-one healthy volunteers (26 men/25 women, mean age = 43 ± 13.51) underwent three CMR exams on three different scanners, using a Modified Look-Locker Inversion Recovery (MOLLI) 5-(3)− 3 sequence to quantify myocardial T1. For T2 mapping, a True Fast Imaging with steady-state free precession (TRUFI) sequence was used on a 3 T Skyra™ (Siemens), and a T2 Fast Spin Echo (FSE) sequence was used on 1.5 T Artist™ (GE) and 3.0 T Premier™ (GE) scanners. The averages of basal and mid-ventricular short axis slices were used to derive means and standard deviations of global mapping values. We used intra-class comparisons (ICC), repeated measures ANOVA, and paired Student’s t-tests for statistical analyses. Results: There was a significant improvement in intra-subject comparability of T1 (ICC of 0.11 (95% CI= −0.018, −0.332) vs 0.78 (95% CI= 0.650, 0.866)) and T2 (ICC of 0.35 (95% CI= −0.053, 0.652) vs 0.83 (95% CI= 0.726, 0.898)) when using z-scores across all three scanners. While the absolute global T1 and T2 values showed a statistically significant difference between scanners (p

Aims We assessed the feasibility of cardiac magnetic resonance (CMR) and the role of myocardial strain in the diagnostic work-up of patients with acute myocardial infarction (AMI) and a clinical suspicion of cardiac rupture (CR). Methods and results Consecutive patients with AMI complicated by CR who underwent CMR were enrolled. Traditional and strain CMR findings were evaluated; new parameters indicating the relative wall stress between AMI and adjacent segments, named wall stress index (WSI) and WSI ratio, were analysed. A group of patients admitted for AMI without CR served as control. 19 patients (63% male, median age 73 years) met the inclusion criteria. Microvascular obstruction (MVO, P = 0.001) and pericardial enhancement (P < 0.001) were strongly associated with CR. Patients with clinical CR confirmed by CMR exhibited more frequently an intramyocardial haemorrhage than controls (P = 0.003). Patients with CR had lower 2D and 3D global radial strain (GRS) and global circumferential strain (in 2D mode P < 0.001; in 3D mode P = 0.001), as well as 3D global longitudinal strain (P < 0.001), than controls. The 2D circumferential WSI (P = 0.010), as well as the 2D and 3D circumferential (respectively, P < 0.001 and P = 0.042) and radial WSI ratio (respectively, P < 0.001 and P : 0.007), were higher in CR patients than controls. Conclusion CMR is a safe and useful imaging tool to achieve the definite diagnosis of CR and an accurate visualization of tissue abnormalities associated with CR. Strain analysis parameters can give insights into the pathophysiology of CR and may help to identify those patients with sub-acute CR. [ABSTRACT FROM AUTHOR]

Heart failure demographics have evolved in past decades with the development of improved diagnostics, therapies, and prevention. Cardiac magnetic resonance (CMR) has developed in a similar timeframe to become the gold-standard non-invasive imaging modality for characterizing diseases causing heart failure. CMR techniques to assess cardiac morphology and function have progressed since their first use in the 1980s. Increasingly efficient acquisition protocols generate high spatial and temporal resolution images in less time. This has enabled new methods of characterizing cardiac systolic and diastolic function such as strain analysis, exercise real-time cine imaging and four-dimensional flow. A key strength of CMR is its ability to non-invasively interrogate the myocardial tissue composition. Gadolinium contrast agents revolutionized non-invasive cardiac imaging with the late gadolinium enhancement technique. Further advances enabled quantitative parametric mapping to increase sensitivity at detecting diffuse pathology. Novel methods such as diffusion tensor imaging and artificial intelligence-enhanced image generation are on the horizon. Magnetic resonance spectroscopy (MRS) provides a window into the molecular environment of the myocardium. Phosphorus (31P) spectroscopy can inform the status of cardiac energetics in health and disease. Proton (1H) spectroscopy complements this by measuring creatine and intramyocardial lipids. Hyperpolarized carbon (13C) spectroscopy is a novel method that could further our understanding of dynamic cardiac metabolism. CMR of other organs such as the lungs may add further depth into phenotypes of heart failure. The vast capabilities of CMR should be deployed and interpreted in context of current heart failure challenges. [ABSTRACT FROM AUTHOR]

Non-invasive quantification of the extracellular volume (ECV) is a method for the evaluation of focal and diffuse myocardial fibrosis, potentially obviating the need for invasive endomyocardial biopsy. While ECV quantification with cardiac magnetic resonance imaging (ECVMRI) is already an established method, ECV quantification with CT (ECVCT) is an attractive alternative to ECVMRI, similarly using the properties of extracellular contrast media for ECV calculation. In contrast to ECVMRI, ECVCT provides a more widely available, cheaper and faster tool for ECV quantification and allows for ECV calculation also in patients with contraindications for MRI. Many studies have already shown a high correlation between ECVCT and ECVMRI and accumulating evidence suggests a prognostic value of ECVCT quantification in various cardiovascular diseases. Adding a late enhancement scan (for dual energy acquisitions) or a non-enhanced and late enhancement scan (for single-energy acquisitions) to a conventional coronary CT angiography scan improves risk stratification, requiring only minor adaptations of the contrast media and data acquisition protocols and adding only little radiation dose to the entire scan. Critical relevance statement This article summarizes the technical principles of myocardial extracellular volume (ECV) quantification with CT, reviews the literature comparing ECVCT with ECVMRI and histopathology, and reviews the prognostic value of myocardial ECV quantification for various cardiovascular disease. Key points • Non-invasive quantification of myocardial fibrosis can be performed with CT. • Myocardial ECV quantification with CT is an alternative in patients non-eligible for MRI. • Myocardial ECV quantification with CT strongly correlates with ECV quantification using MRI. • Myocardial ECV quantification provides incremental prognostic information for various pathologies affecting the heart (e.g., cardiac amyloidosis). [ABSTRACT FROM AUTHOR]

Purpose High-contrast tissue characterization of thermal ablation has been desired to evaluate therapeutic outcomes accurately. This paper presents a photoacoustic (PA) characterization of thermal tissue ablation in the visible spectrum, in which higher light absorbance can produce spectral contrast starker than in the near-infrared range. Methods Ex vivo experiments were performed to measure visible PA spectra (480–700 nm) from fresh porcine liver tissues that received a thermal dose in a range of cumulative equivalent minutes at 43°C (CEM43). The local hemoglobin lobe area between 510–600 nm and whole-spectral area under the curve were evaluated to represent the transition of hemoglobin into methemoglobin (MetHb) in the target tissue. Results The thermal process below an estimated therapeutic CEM43 threshold (80–340 minutes) presented a progressive elevation of the PA spectrum and an eventual loss of local hemoglobin peaks in the visible spectrum, closer to the MetHb spectrum. Interestingly, an excessive CEM43 produced a substantial drop in the PA spectrum. In the spectral analysis, the visible spectrum yielded 13.9–34.1 times higher PA sensitivity and 1.42 times higher contrast change than at a near-infrared wavelength. Conclusion This novel method of PA tissue characterization in the visible spectrum could be a potential modality to evaluate various thermal therapeutic modalities at high-contrast resolution.

Nguyen Duy Hung,1,2,&ast; Nguyen-Thi Tam,2 Dang Khanh Huyen,2 Nguyen-Van Thi,3 Nguyen Minh Duc4,&ast; 1Department of Radiology, Viet Duc Hospital, Hanoi, Vietnam; 2Department of Radiology, Hanoi Medical University, Hanoi, Vietnam; 3Department of Radiology, Vietnam National Cancer Hospital, Hanoi, Vietnam; 4Department of Radiology, Pham Ngoc Thach University of Medicine, Ho Chi Minh City, Vietnam&ast;These authors contributed equally to this workCorrespondence: Nguyen Minh Duc, Department of Radiology, Pham Ngoc Thach University of Medicine, 2 Duong Quang Trung Ward 12 District 10, Ho Chi Minh City, 700000, Vietnam, Email bsnguyenminhduc@pnt.edu.vnObjective: The study aimed to evaluate the role of magnetic resonance imaging (MRI) in differentiating between primary benign and malignant soft tissue tumors (STTs).Patients and Methods: The study was carried out on 110 patients with histopathological diagnoses of STTs. All patients underwent routine MRI before surgery/biopsy at Viet Duc University Hospital or Vietnam National Cancer Hospital, Hanoi, Vietnam, from January 2020 to October 2022. Data on preoperative MRI as well as the clinical features and pathological results of the patients were collected retrospectively. Univariate and multivariate linear regression were used to analyze the relationship between imaging, clinical parameters, and the ability to differentiate malignant from benign STTs.Results: Among 110 patients (59 men and 51 women), 66 had benign tumors and 44 had malignant tumors. The qualitative values that were significant in distinguishing between benign and malignant STTs were hypointensity on T1-weighted images (T1W; p< 0.001), hypointensity on T2-weighted images (T2W; p=0.003), cysts (p=0.003)), necrosis (p< 0.001), fibrosis (p=0.023), hemorrhage (p< 0.001), lobulated margin (p< 0.001), ill-defined border (p< 0.001), peritumoral edema (p< 0.001), vascular involvement (p< 0.001), and heterogeneous enhancement (p< 0.001). Regarding quantitative values, age (p=0.009), size (p< 0.001), T1W signal quantification value (p=0.002), and T2W signal quantification value (p=0.007) showed statistically significant differences between benign and malignant tumors. Multivariate linear regression analysis showed that the combination of peritumoral edema and heterogeneous enhancement was the most valuable in the differential diagnosis of malignant tumors from benign tumors.Conclusion: MRI is valuable in discriminating between malignant and benign STTs. The presence of cysts, necrosis, hemorrhage, lobulated margin, ill-defined border, peritumoral edema, heterogeneous enhancement, vascular involvement, and T2W hypointensity is suggestive of malignant lesions, especially signs of peritumoral edema and heterogeneous enhancement. Advanced age and large tumor size are also suggestive of soft tissue sarcomas.Keywords: soft tissue tumors, soft tissue sarcoma, magnetic resonance imaging, tissue characterization, size, prediction

Ultrasound backscattered signals encompass information on the microstructure of heterogeneous media such as cortical bone, in which pores act as scatterers and result in the scattering and multiple scattering of ultrasound waves. The objective of this study was to investigate whether Shannon entropy can be exploited to characterize cortical porosity. In the study described here, to demonstrate proof of concept, Shannon entropy was used as a quantitative ultrasound parameter to experimentally evaluate microstructural changes in samples with controlled scatterer concentrations made of a highly absorbing polydimethylsiloxane matrix (PDMS). Similar assessment was then performed using numerical simulations on cortical bone structures with varying average pore diameter (Ct.Po.Dm.), density (Ct.Po.Dn.) and porosity (Ct.Po.). The results suggest that an increase in pore diameter and porosity lead to an increase in entropy, indicating increased levels of randomness in the signals as a result of increased scattering. The entropy-versus-scatterer volume fraction in PDMS samples indicates an initial increasing trend that slows down as the scatterer concentration increases. High levels of attenuation cause the signal amplitudes and corresponding entropy values to decrease drastically. The same trend is observed when porosity of the bone samples is increased above 15%. Sensitivity of entropy to microstructural changes in highly scattering and absorbing media can potentially be exploited to diagnose and monitor osteoporosis. [ABSTRACT FROM AUTHOR]

Methods to assess ultrasound backscatter anisotropy from clinical array transducers have recently been developed. However, they do not provide information about the anisotropy of microstructural features of the specimens. This work develops a simple geometric model, referred to as the secant model, of backscatter coefficient anisotropy. Specifically, we evaluate anisotropy of the frequency dependence of the backscatter coefficient parameterized in terms of effective scatterer size. We assess the model in phantoms with known scattering sources and in a skeletal muscle, a well-known anisotropic tissue. We demonstrate that the secant model can determine the orientation of the anisotropic scatterers, as well as accurately determining effective scatterer sizes, and it may classify isotropic versus anisotropic scatterers. The secant model may find utility in monitoring disease progression as well as characterizing normal tissue architectures. [ABSTRACT FROM AUTHOR]

Purpose: Tensor‐valued diffusion encoding can probe more specific features of tissue microstructure than what is available by conventional diffusion weighting. In this work, we investigate the technical feasibility of tensor‐valued diffusion encoding at high b‐values with q‐space trajectory imaging (QTI) analysis, in the human heart in vivo. Methods: Ten healthy volunteers were scanned on a 3T scanner. We designed time‐optimal gradient waveforms for tensor‐valued diffusion encoding (linear and planar) with second‐order motion compensation. Data were analyzed with QTI. Normal values and repeatability were investigated for the mean diffusivity (MD), fractional anisotropy (FA), microscopic FA (μFA), isotropic, anisotropic and total mean kurtosis (MKi, MKa, and MKt), and orientation coherence (Cc). A phantom, consisting of two fiber blocks at adjustable angles, was used to evaluate sensitivity of parameters to orientation dispersion and diffusion time. Results: QTI data in the left ventricular myocardium were MD = 1.62 ± 0.07 μm2/ms, FA = 0.31 ± 0.03, μFA = 0.43 ± 0.07, MKa = 0.20 ± 0.07, MKi = 0.13 ± 0.03, MKt = 0.33 ± 0.09, and Cc = 0.56 ± 0.22 (mean ± SD across subjects). Phantom experiments showed that FA depends on orientation dispersion, whereas μFA was insensitive to this effect. Conclusion: We demonstrated the first tensor‐valued diffusion encoding and QTI analysis in the heart in vivo, along with first measurements of myocardial μFA, MKi, MKa, and Cc. The methodology is technically feasible and provides promising novel biomarkers for myocardial tissue characterization. [ABSTRACT FROM AUTHOR]

Objectives: H‐scan ultrasound (US) imaging is a novel tissue characterization technique to detect apoptosis‐induced changes in cancer cells after the initiation of effective drug treatment. The objective of the proposed research was to assess the sensitivity of 3‐dimensional (3D) H‐scan US technique for monitoring the response of breast cancer‐bearing animals to neoadjuvant chemotherapy and correlate results to diffusion‐weighted magnetic resonance imaging (DW‐MRI) measurements of programmed cancer cell death. Methods: Experimental studies used female mice (N = 18) implanted with human breast cancer cells. Animals underwent H‐scan US and DW‐MRI imaging on days 0, 1, 3, 7, and 10. After imaging at day 0, breast tumor‐bearing nude mice were treated biweekly with an apoptosis‐inducing drug. Texture analysis of H‐scan US images explored spatial relationships between local US scattering. At day 10, H‐scan measurements were compared with DW‐MRI‐derived apparent diffusion coefficient (ADC) values and histological findings. Results: H‐scan US imaging of low and high dose cisplatin‐treated cancer‐bearing animals revealed changes in image intensity suggesting a progressive decrease in aggregate US scatterer size that was not observed in control animals. Longitudinal trends discovered in H‐scan US result matched with texture analysis and DW‐MRI (P <.01). Further, analysis of the H‐scan US image intensity and corresponding DW‐MRI‐derived ADC values revealed a strong linear correlation (R2 =.93, P <.001). These changes were due to cancer cell apoptotic activity and consider as early detectable biomarker during treatment. Conclusions: The 3D H‐scan technique holds promise for assisting clinicians in monitoring the early response of breast cancer tumor to neoadjuvant chemotherapy and adding value to traditional diagnostic ultrasound examinations. [ABSTRACT FROM AUTHOR]

Purpose: Radiomics of vertebral bone structure is a promising technique for identification of osteoporosis. We aimed at assessing the accuracy of machine learning in identifying physiological changes related to subjects' sex and age through analysis of radiomics features from CT images of lumbar vertebrae, and define its generalizability across different scanners. Materials and methods: We annotated spherical volumes-of-interest (VOIs) in the center of the vertebral body for each lumbar vertebra in 233 subjects who had undergone lumbar CT for back pain on 3 different scanners, and we evaluated radiomics features from each VOI. Subjects with history of bone metabolism disorders, cancer, and vertebral fractures were excluded. We performed machine learning classification and regression models to identify subjects' sex and age respectively, and we computed a voting model which combined predictions. Results: The model was trained on 173 subjects and tested on an internal validation dataset of 60. Radiomics was able to identify subjects' sex within single CT scanner (ROC AUC: up to 0.9714), with lower performance on the combined dataset of the 3 scanners (ROC AUC: 0.5545). Higher consistency among different scanners was found in identification of subjects' age (R2 0.568 on all scanners, MAD 7.232 years), with highest results on a single CT scanner (R2 0.667, MAD 3.296 years). Conclusion: Radiomics features are able to extract biometric data from lumbar trabecular bone, and determine bone modifications related to subjects' sex and age with great accuracy. However, acquisition from different CT scanners reduces the accuracy of the analysis. [ABSTRACT FROM AUTHOR]

Breathing involves fluid-solid interactions in the lung; however, the lack of experimental data inhibits combining the mechanics of air flow to airway deformation, challenging the understanding of how biomaterial constituents contribute to tissue response. As such, lung mechanics research is increasingly focused on exploring the relationship between structure and function. To address these needs, we characterize mechanical properties of porcine airways using uniaxial tensile experiments, accounting for bronchial orientation- and location- dependency. Structurally-reinforced constitutive models are developed to incorporate the role of collagen and elastin fibers embedded within the extrafibrillar matrix. The strain-energy function combines a matrix description (evaluating six models: compressible NeoHookean, unconstrained Ogden, uncoupled Mooney-Rivlin, incompressible Ogden, incompressible Demiray and incompressible NeoHookean), superimposed with non-linear fibers (evaluating two models: exponential and polynomial). The best constitutive formulation representative of all bronchial regions is determined based on curve-fit results to experimental data, accounting for uniqueness and sensitivity. Glycosaminoglycan and collagen composition, alongside tissue architecture, indicate fiber form to be primarily responsible for observed airway anisotropy and heterogeneous mechanical behavior. To the authors best knowledge, this study is the first to formulate a structurally-motivated constitutive model, augmented with biochemical analysis and microstructural observations, to investigate the mechanical function of proximal and distal bronchi. Our systematic pulmonary tissue characterization provides a necessary foundation for understanding pulmonary mechanics; furthermore, these results enable clinical translation through simulations of airway obstruction in disease, fluid-structure interaction insights during breathing, and potentially, predictive capabilities for medical interventions. STATEMENT OF SIGNIFICANCE: The advancement of pulmonary research relies on investigating the biomechanical response of the bronchial tree. Experiments demonstrating the non-linear, heterogeneous, and anisotropic material behavior of porcine airways are used to develop a structural constitutive model representative of proximal and distal bronchial behavior. Calibrated material parameters exhibit regional variation in biomaterial properties, initially hypothesized to originate from tissue constituents. Further exploration through biochemical and histological analysis indicates mechanical function is primarily governed by microstructural form. The results of this study can be directly used in finite element and fluid-structure interaction models to enable physiologically relevant and more accurate computational simulations aimed to help diagnose and monitor pulmonary disease.

PurposeTo evaluate the accuracy and repeatability of a free-breathing, non-electrocardiogram (ECG), continuous myocardial T1 and extracellular volume (ECV) mapping technique adapted from the Multitasking framework.MethodsThe Multitasking framework is adapted to quantify both myocardial native T1 and ECV with a free-breathing, non-ECG, continuous acquisition T1 mapping method. We acquire interleaved high-spatial resolution image data and high-temporal resolution auxiliary data following inversion-recovery pulses at set intervals and perform low-rank tensor imaging to reconstruct images at 344 inversion times, 20 cardiac phases, and 6 respiratory phases. The accuracy and repeatability of Multitasking T1 mapping in generating native T1 and ECV maps are compared with conventional techniques in a phantom, a simulation, 12 healthy subjects, and 10 acute myocardial infarction patients.ResultsIn phantoms, Multitasking T1 mapping correlated strongly with the gold-standard spin-echo inversion recovery (R2 = 0.99). A simulation study demonstrated that Multitasking T1 mapping has similar myocardial sharpness to the fully sampled ground truth. In vivo native T1 and ECV values from Multitasking T1 mapping agree well with conventional MOLLI values and show good repeatability for native T1 and ECV mapping for 60 seconds, 30 seconds, or 15 seconds of data. Multitasking native T1 and ECV in myocardial infarction patients correlate positively with values from MOLLI.ConclusionMultitasking T1 mapping can quantify native T1 and ECV in the myocardium with free-breathing, non-ECG, continuous scans with good image quality and good repeatability in vivo in healthy subjects, and correlation with MOLLI T1 and ECV in acute myocardial infarction patients.