Ultrasound in Medicine & Biology

BackgroundTumor progression is associated with alterations in tissue mechanical properties. Experimental studies in cancer mechanobiology suggest that increased viscosity of the tumor habitat can promote tumor growth, while malignant tumors often exhibit pronounced mechanical heterogeneity with coexisting soft and rigid regions that facilitate cell motility. Elastography enables noninvasive viscoelastic profiling of soft-tissue properties in vivo and may therefore detect tumor malignancy. PurposeTo investigate whether multiparametric external vibration-based ultrasound time-harmonic elastography (THE) can differentiate benign from malignant liver tumors and identify viscoelastic parameters associated with tumor malignancy. Materials and MethodsIn this prospective study conducted from January 2025 to March 2026, 94 patients with focal liver lesions underwent THE. Eighty-four patients were included in the final analysis (41 benign, 39 malignant; 45 women; age range 30-87 years). Liver and tumor stiffness (shear wave speed; SWS), viscosity (loss angle; {phi}), and spatial mechanical heterogeneity (spatial standard deviation, SWS-SD) were quantified. Diagnostic performance for differentiating benign and malignant tumors was assessed using the area under the receiver operating characteristic curve (AUC). ResultsTumor heterogeneity and surrounding habitat viscosity provided the most pronounced differentiation between malignant and benign lesions. Malignant tumors demonstrated higher SWS-SD (0.41{+/-}0.20 vs. 0.28{+/-}0.11 m/s) and increased {phi} (0.76{+/-}0.09 vs. 0.71{+/-}0.05 rad) with a combined discriminative power of AUC=0.72. These viscoelastic differences were more pronounced in larger tumors of [≥]2.5 cm2 area (SWS-SD: 0.47{+/-}0.19 vs. 0.32{+/-}0.11 m/s; {phi}: 0.78{+/-}0.10 vs 0.70{+/-}0.04 rad) yielding AUC=0.88 while excellent discriminative power of AUC=0.97 for [≥]6 cm2 tumor area. ConclusionElevated viscosity of the tumor habitat combined with increased tumor stiffness-heterogeneity measured by multiparametric THE can differentiate liver malignancies from benign liver lesions. THE may thus provide a rapid, cost-effective approach for viscoelastic profiling of liver tumors in clinical diagnostic imaging.

ObjectiveThis study aimed to develop a machine learning method for characterizing muscle composition on ultrasound imaging, focusing on pixel-level quantification of connective tissue using texture analysis. MethodsUltrasound images of the multifidus muscle from 20 healthy young adults were included in the analysis. Texture features including Local Binary Patterns, Histograms of Oriented Gradients, Grey Level Co-occurrence Matrix, and Discrete Wavelet Transforms, were extracted from the images across multiple scales. Within a positive-unlabeled machine learning framework, two competing models, Bagging Support Vector Machine and Random Forests with Recursive Greedy Risk Minimization were trained for each texture and scale. The outputs of the texture-based pixel-level classification were compared to traditional echo intensity-based methods. Metrics such as the F-measure were employed to evaluate the models performance. Expert consensus was utilised to evaluate the accuracy of the classified images and identify the best-performing combination of model, texture, and scale. ResultsExpert evaluation identified the Bagging Support Vector Machine model trained with Local Binary Pattern histograms extracted at a scale of 9x9 pixel region of interest as the best combination for accurately classifying connective tissue-like pixels (F-measure= 0.88). The proposed method demonstrated high repeatability (intraclass correlation coefficient= 0.92) and robustness to echo intensity variations, outperforming traditional echo intensity-based methods. ConclusionThis approach offers a valid method for pixel-level quantification of intramuscular connective tissue from ultrasound images. It overcomes the limitations of traditional analyses relying on echo intensity and demonstrates robustness against variations in echo intensity, representing an operator-independent advancement in ultrasound-based muscle composition analysis.

Background Perioperative incidents such as hypoxic cardiac injury often have subtle or nonspecific clinical manifestations. Reduction in myocardial oxygenation precedes biochemical changes, as well as electrical and functional changes. Photoacoustic imaging (PAI) is a modality that uses laser irradiation of tissue to generate ultrasonic waves, enabling spatially resolved quantitative mapping of oxygenated and deoxygenated haemoglobin. We investigated the utility of PAI for real-time monitoring of myocardial and great vessel oxygenation. Methods Male CD-1 mice were anaesthetised, and photoacoustic and simultaneous B-mode images were acquired of the myocardium and right ventricular outflow tract (RVOT), the pulmonary artery, and aorta. PAI was performed at fractional inspired oxygen levels (FiO2) of 100%, 21%, and then 10%. Separate cohorts of mice were exposed to increasing intravenous doses of either combined phenylephrine and isoprenaline, or individual administration of vasoactive or adrenergic agents. Results PAI reliably distinguished changes in oxygenation in the RVOT cavity, pulmonary artery, aorta, and myocardium. PAI detected hypoxia-induced changes in oxygenation, revealing greater desaturation in the myocardium than in the RVOT (-9.85%, 95% CI -14.94 to -4.77, P<0.0001). Escalating doses of phenylephrine and isoprenaline caused a progressive desaturation of the myocardium and RVOT (mean [95% CI]; myocardium 16 mg/kg: -14.64% [-27.62 to -1.65], P=0.0038 and RVOT 32 mg/kg: -18.71% [-32.15 to -5.27], P=0.0003). Myocardial deoxygenation was detected before changes in systolic function or electrical abnormalities. Conclusions This work demonstrates that PAI can reliably monitor cardiac oxygen desaturation, potentially offering an earlier warning of cardiac dysfunction and injury compared to existing monitoring tools. Keywords: Echocardiography, hypoxaemia, hypoxia, myocardial injury, oxygenation, perioperative monitoring, photoacoustic imaging

BackgroundInterpretation of lung ultrasound artifacts by clinicians can be inconsistent. Artificial intelligence (AI) may perform this task more consistently. Research QuestionCan AI characterize lung ultrasound artifacts similarly to humans, and can AI interpretation be corroborated by clinical data? Study Design and MethodsLung sonograms (n=665) from a convenience sample of 172 subjects were prospectively obtained using a pre-specified protocol and matched to clinical and radiographic data. Three investigators scored sonograms for A-lines and B-lines. AI was trained using 142 subjects and then tested on a separate dataset of 30 patients. Three radiologists scored similar anatomic regions of contemporary radiographs for interstitial and alveolar infiltrates to corroborate sonographic findings. The ratio of oxyhemoglobin saturation:fraction of inspired oxygen (S/F) was also used for comparison. The primary outcome was the intraclass correlation coefficient (ICC) between the median investigator scoring of artifacts and AI interpretation. ResultsIn the test set, the correlation between the median investigator score and the AI score was moderate to good for A lines (ICC 0.73, 95% CI [0.53-0.89]), and moderate for B lines (ICC 0.66, 95% CI [0.55-0.75]). The degree of variability between the AI score and the median investigator score for each video was similar to the variability between each investigators score and the median score. The correlation among radiologists was moderate (ICC 0.59, 95% CI [0.52-0.82]) for interstitial infiltrates and poor for alveolar infiltrates (ICC 0.33, 95% CI [0.07-0.58]). There was a statistically significant correlation between AI scored B-lines and the degree of interstitial opacities for five of six lung zones. Neither AI nor human-scored artifacts were consistently associated with S/F. InterpretationUsing a limited dataset, we showed that AI can interpret lung ultrasound A-lines and B-lines in a fashion that could be clinically useful.

BackgroundLiver tumor remains an important cause of cancer-related death. Nanosecond pulsed electric fields (nsPEFs) are advantageous in the treatment of melanoma and pancreatic cancer, but their therapeutic application on liver tumors need to be further studied. MethodsHep3B cells were treated with nsPEFs. The biological behaviors of cells were detected by Cell Counting Kit-8, 5-ethynyl-20-deoxyuridine, and transmission electron microscopy (TEM) assays. In vivo, rabbit VX2 liver tumor models were ablated by ultrasound-guided nsPEFs and radiofrequency ablation (RFA). Contrast-enhanced ultrasound (CEUS) was used to evaluate the ablation effect. HE staining and Masson staining were used to evaluate the tissue morphology after ablation. Immunohistochemistry was performed to determine the expression of Ki67, proliferating cell nuclear antigen, and -smooth muscle actin at different time points after ablation. ResultsThe cell viability of Hep3B cells was continuously lower than that of the control group within 3 days after pulse treatment. The proliferation of Hep3B cells was significantly affected by nsPEFs. TEM showed that Hep3B cells underwent significant morphological changes after pulse treatment. In vivo, CEUS imaging showed that nsPEFs could completely ablate model rabbit VX2 liver tumors. After nsPEFs ablation, the area of tumor fibrosis and the expression of Ki67, proliferating cell nuclear antigen, and -smooth muscle actin were decreased. However, after RFA, rabbit VX2 liver tumor tissue showed complete necrosis, but the expression of PCNA and -smooth muscle actin did not decrease compared to the tumor group. ConclusionsnsPEFs can induce Hep3B cells apoptosis and ablate rabbit VX2 liver tumors in a non-thermal manner versus RFA. The ultrasound contrast agent can monitor immediate effect of nsPEF ablation. This study provides a basis for the clinical study of nsPEFs ablation of liver cancer.

BackgroundDeep brain structures are supplied by perforating arteries, these arteries are too thin to be observed with non-invasive and widely available clinical imaging methods. In Moya Moya disease, main arteries in the base of the brain progressively narrowed, and perforating arteries grow densely and tortuously to compensate the lack of blood supply in deep brain structures. PurposeThe aim of this study is to evaluate the efficacy of transcranial ultrasound localization microscopy (ULM) in visualizing perforating arteries, utilizing a standard low-frame-rate ultrasound clinical scanner and contrast sequences commonly employed in hospital settings. MethodsThis prospective single-center study included ischemic stroke patients not related to perforating arteries, i.e. control patients, and Moya Moya disease patients (n{degrees} 2022-A02486-37). Contrast-enhanced ultrasound sequences (CEUS) were performed by an experienced neurologist and the images acquired were used to perform post-processing ULM. ULM density maps, i.e. number of microbubbles tracked per pixel, were compared with conventional 3T TOF MRI and color Doppler imaging (one-way ANOVA test). We also compared ULM density maps between the control and Moya Moya groups (two-sided parametric Students t-tests, or Mann-Whitney test). ResultsWe included a group of 15 control patients and another group of 9 Moya Moya patients between March 2023 and March 2024. The patients had an average age of 45 years with 65% of them being male. Perforating arteries were captured on all subjects, with a mean diameter of 0.8 {+/-} 0.3 mm in control patients, while it was not so far possible with TOF MRI or color Doppler (P < 0.05). Moreover, ULM enabled the differentiation between healthy subjects and those with Moya Moya disease through track mean distance (P = 0.05). ConclusionsUsing a low-frame-rate ultrasound scanner, CEUS and accessible post-processing tools, we have demonstrated that transcranial ULM can facilitate the visualization and characterization of perforating arteries, even in cases where they were previously undetectable using standard non-invasive imaging techniques. We speculate that with the advent of high-frame-rate 3D ULM, this technique may find widespread utility in hospitals. Key Results- 2D low-frame rate Ultrasound Localization Microscopy (ULM) allows visualization of perforating arteries, i.e. diameter of 0.8 {+/-} 0.3 mm. - ULM described vessels that were not visible in conventional imaging techniques, i.e. TOF MRI and color Doppler. - ULM reconstruction and quantification of the perforating arteries enabled the pathological group (Moya Moya) to be distinguished from control subjects. Summary statementTranscranial 2D ULM performed with a standard low frame-rate clinical ultrasound scanner enabled visualization and morphological description of perforating arteries. The study involved 24 subjects, including 9 Moya Moya patients.

BackgroundTo assess whether radiomics analysis of carotid ultrasound (CUS) can identify texture features associated with severe coronary artery calcification, even in individuals without carotid plaque. MethodsThis study included 105 participants with coronary artery calcium score (CACS) > 400 and no carotid plaque, matched by age and sex to 105 controls with CACS=0. B-mode CUS images of the bilateral distal common carotid arteries (CCA) were analyzed, with 1-cm longitudinal regions of interest extending from the lumen to the adventitia. Radiomic features were extracted from each frame, filtered by variance and correlation, and ranked using bootstrap-based XGBoost feature importance (FI) and evaluated on internal and external datasets. ResultsAmong 700 extracted features, the final retained features were reproducible: 8 (right) and 11 (left) for CACS=0, and 7 (right) and 10 (left) for CACS > 400 (all p < 0.05). Group-specific features, observed only in the CACS 0 or CACS > 400 group, included 90th Percentile (CACS=0: right distal CCA, FI=0.030; left distal CCA, FI=0.025) and Run Entropy (CACS > 400: right distal CCA, FI=0.046; left distal CCA, FI=0.038). Shared features such as Long Run Emphasis, Dependence Non-Uniformity, and Entropy were consistently observed across both groups and sides (FI=0.023-0.029), with Dependence Non-Uniformity consistent in the left distal CCA across both groups and datasets. ConclusionsAlthough no plaque was detected on CUS, radiomics can identify ultrasound texture patterns associated with severe coronary calcification. This approach may improve detection of high-risk individuals who would otherwise be classified as low-risk by CUS alone. Graphic AbstractTexture-Based Radiomics of Carotid Ultrasound Reveals Severe Coronary Calcification. (A), Imaging modalities and study population: Adults undergoing health screenings at tertiary hospitals in City A and City B (2018-2022) who received same-day carotid ultrasound and CACS CT. After excluding plaque, CVD history, and poor image quality, 105 plaque-free participants with CACS > 400 were identified and age- and sex-matched to 105 plaque-free participants with CACS = 0. (B), Radiomics pipeline: carotid ultrasound images were segmented, preprocessed, filtered, and processed for feature extraction and selection, yielding reproducible texture features. (C), Radiomics feature maps: representative examples of plaque-free carotid ultrasound in patients with CACS = 0 and CACS >400. Entropy and dependence non-uniformity maps demonstrate distinct texture patterns associated with severe coronary calcification. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=128 SRC="FIGDIR/small/25337136v1_ufig1.gif" ALT="Figure 1"> View larger version (51K): org.highwire.dtl.DTLVardef@eb2b93org.highwire.dtl.DTLVardef@179c26aorg.highwire.dtl.DTLVardef@caf446org.highwire.dtl.DTLVardef@6b2325_HPS_FORMAT_FIGEXP M_FIG C_FIG

Purpose: Accurate assessment of the pressure gradient ({Delta}P) across aortic coarctation (CoA) is critical for determining disease severity and the need for intervention. Current non-invasive methods are unreliable, while invasive catheterization remains the clinical gold standard. This study evaluates a novel MRI acquisition strategy, 4D-FlowP, that simultaneously encodes blood velocity and acceleration to enable reliable non-invasive pressure gradient mapping in CoA. Methods: Patient-specific compliant aortic phantoms were created from clinical MRI data of two patients with CoA. Additional geometries were synthetically generated by increasing stenosis severity. Phantoms were studied in an MRI compatible flow loop under physiologically realistic flow and pressure conditions. Pressure gradients were estimated using conventional 4D-Flow MRI, 4D-FlowP, and fluid-structure interaction (FSI) simulations. Results were compared against ground-truth catheter-based measurements across multiple flow rates and stenosis severities. Results: Conventional 4D-Flow consistently underestimated {Delta}P (slope = 0.63, R2=0.75) relative to catheter measurements. In contrast, 4D-FlowP demonstrated substantially improved agreement (slope = 0.95, R2=0.75). FSI simulations showed the highest overall agreement with catheter-derived {Delta}P (slope = 1.14, R2=0.82). Scan times for 4D-FlowP were comparable to 4D-Flow (26 vs. 24 minutes). Conclusion: 4D-FlowP enables a more accurate MRI-based pressure gradient mapping in CoA than conventional 4D-Flow, when compared to ground truth catheter measurements. These findings support further in vivo evaluation of 4D-FlowP as a non-invasive alternative for functional assessment of CoA severity

Skeletal muscle is a living, perfused soft tissue whose viscoelastic behavior is shaped by both voluntary contraction and hemodynamic state. However, the independent and superimposed contributions of contractile loading and blood flow restriction (BFR) have not been quantified simultaneously in real time. Twenty-six healthy adults underwent multi-frequency ultrasound time-harmonic elastography (THE, 60-80 Hz) of the vastus lateralis under six conditions: rest, 15% and 30% maximal voluntary contraction (MVC) before BFR, passive BFR after 4 min of cuff inflation, and 15% and 30% MVC shortly after cuff release. Shear wave speed (SWS), reflecting elasticity, and penetration rate (PR), reflecting inverse viscous damping, were extracted using the k-MDEV inversion algorithm. BFR significantly elevated SWS at all three contraction levels relative to the corresponding pre-BFR measurements (Holm-corrected p [&le;] 0.011; dz = 0.54-2.13). PR decreased during resting BFR (dz = 1.34, p < 0.001) and at 15% MVC after cuff release (dz = 0.94, p < 0.001), but not at 30% MVC (dz = 0.21, p = 0.294). BFR-related changes reduced the SWS-force slope by 14.5% and the PR-force slope by 40.7%. Men exhibited a greater BFR-induced increase in resting SWS than women. These findings show that THE can distinguish contractile and hemodynamic contributions to skeletal-muscle viscoelasticity and provide complementary information on elastic and dissipative tissue behavior in vivo.

IntroductionUltrasound is a relatively inexpensive and non-ionizing imaging modality, but is under-utilized in large airway assessments due to poor image quality. No commercially available contrast agents currently exist for sonographic evaluation of the respiratory system, nor has a respiratory route of microbubble contrast agent (MCA) administration been previously described for the enhancement of airway imaging. MethodsWe conducted a feasibility study to assess proof-of-concept for an inhalable ultrasound MCA composed of lipid-encapsulated decaflourobutane gas. The MCA was nebulized and administered as an aerosol through the lumen of an ex vivo porcine trachea, with image enhancement evaluated by comparing images pre- and post-exposure. Additionally, primary human bronchial epithelial (hBE) cells from three donors were differentiated at an air-liquid interface and exposed apically to 25 L of undiluted MCA or vehicle control to assess contrast agent-induced cytotoxicity and inflammation. Basolateral medium was collected 24-hours post-exposure and lactate dehydrogenase (LDH) and interleukin-8 (IL-8) concentrations were measured as biomarkers of cytotoxicity and inflammation, respectively. ResultsContrast microbubbles remained intact following nebulization and enhanced sonographic delineation of ex vivo porcine tracheal walls, indicating adherence of the nebulized MCA to the lumenal mucosa. No significant cytotoxic or inflammatory effects were observed in cultured hBE cells following exposure to MCA. ConclusionsWe present proof-of-concept for an inhaled MCA for the enhancement of sonographic evaluations of the large airways. Pending further evaluations for safety and effectiveness, inhaled MCA may be feasible for clinical ultrasound applications, such as enhancing ultrasound-guided tracheal intubation, detecting airway bleeds, or monitoring large airway diseases in pediatric populations.

BackgroundDeep learning (DL) programs can aid in the acquisition of echocardiograms by medical professionals not previously trained in sonography, potentially addressing access issues in underserved communities. This study evaluates whether DL-enabled devices improve limited echocardiogram acquisition by novice clinicians not trained on sonography. MethodsIn this single-center randomized controlled trial (2023-2024), internal medicine residents (N=38) without sonography training received a personal ultrasound device with (N=19) or without (N=19) DL capability for two weeks while caring for patients on a hospital ward. Participants were allowed to use the devices at their discretion for patient-related care. The DL software provided real-time guidance for probe placement and image quality assessment. The primary outcome was time to acquire a five-view limited echocardiogram. Measurements occurred at randomization and after two weeks, with all scans performed on the same standardized patient. Secondary outcomes included image quality using the modified Rapid Assessment for Competency in Echocardiography (RACE) scale and participant attitudes. ResultsAt baseline, both groups had comparable scan times and image quality scores. At follow-up, the DL group demonstrated significantly faster total scan times (152 seconds [IQR 115-195] vs. 266 seconds [IQR 206-324]; p<0.001; Cohens D 1.7) and better image quality with higher RACE scores (15 [IQR 10-18] vs. 11 [IQR 7-13.5]; p=0.034; Cohens D 0.84). Trust in the AI features did not differ between the groups post-intervention. ConclusionsUltrasound machines with DL features may improve image acquisition times and image quality by novices not trained in sonography. These findings suggest DL algorithms could help address critical gaps in image acquisition by healthcare professionals.

ObjectiveThe primary objective of our study was to investigate the efficiency of high intensity focused ultrasound (HIFU) ablation in two distinct cellular configurations, 2D monolayers and 3D spheroids of epithelial breast cancer cell lines. The study also compares empirical findings from experiments with results obtained through numerical simulations using a bioheat computational model. This comparison is intended to provide a comprehensive understanding of the acoustic energy conversion within the biological system during HIFU treatment. MethodsHIFU was applied to 2D and 3D cultured MDA-MB 231 and MCF7 epithelial breast cancer cell lines while systematically varying ultrasound intensity and duty cycle (DC) during sonication sessions of different durations. Temperature elevation was measured and the ablation percentage was calculated based on bright field and fluorescent imaging of the treated regions. Experimental results were validated through simulations of the ablation setup. ResultsUpon HIFU, spheroids exhibited a lower temperature increase (approximately 20 {degrees}C) when subjected to comparable acoustic intensities and duty cycles. The level of tumor ablation was highly influenced by DC, with higher DCs leading to greater ablation percentages. However, sonication duration had a minimal impact on the degree of ablation. Numerical simulations corroborated these observations, demonstrating uniform heat distribution within the cultured cells. At higher DCs and intensities, complete ablation of spheroids was achieved, whereas at lower levels, only the outermost layers exhibited ablation. ConclusionOur study reveals a significant disparity in the response of 2D monolayers and 3D spheroids to HIFU treatment. Specifically, tumor spheroids require lower temperature elevations for effective ablation, and their ablation percentage significantly increases with elevated DC.

While proximal isovelocity surface area (PISA) method is one of the most common echocardiographic methods for quantitative mitral regurgitation (MR) assessment, accurate MR quantification remains challenging. This study examined the theoretical background of PISA, performed virtual echocardiography on computer models of functional MR, and quantified different sources of errors in PISA. For regurgitant flow rate measurement, the conventional 2D hemispherical PISA caused significant underestimation due to underestimation of PISA area, the multiplane 2D hemiellipsoidal and hemicylindrical PISA provided improved accuracy with better assumptions on PISA contour shape. With the direct capture of PISA area, the 3D-PISA was found to be the most accurate. However, it should be noted that PISA method is subject to systematic underestimation due to the Doppler angle effect, and systematic overestimation due to the "flow direction angle" between the regurgitant flow direction and the PISA contour normal direction. For regurgitant volume quantification, integrated PISA, when performed properly, was able to capture the dynamic MR and therefore was more accurate than peak PISA. In specific, integrated PISA using the sum of regurgitant flow rates is recommended. ObjectivesThe aim of this study was to evaluate the accuracy of different proximal isovelocity surface area (PISA) methods, examine their theoretical background, and quantify multiple sources of error in functional mitral regurgitation (MR) assessment. BackgroundWhile PISA method is one of the most common echocardiographic methods for MR severity assessment, it is associated with multiple sources of errors, and accurate MR quantification remains challenging. MethodsFive functional MR (FMR) computer models were created, validated and treated as phantom models. The phantom models have fully resolved and detailed flow fields in the left atrium (LA), left ventricle (LV) and cross the mitral valve, from which the reference values of mitral regurgitant flow rate and regurgitant volume can be obtained. The virtual PISA measurements (i.e., 3D and 2D PISA) were performed on the phantom models assuming optimal echo probe angulation and positioning. The results of different PISA methods were compared with the reference values. ResultsFor regurgitant flow rate measurements, compared to the reference values, excellent correlations were observed for 3D-PISA (R = 0.97, bias -24.4 {+/-} 55.5 ml/s), followed by multiplane 2D hemicylindrical (HC)-PISA (R = 0.88, bias -24.1 {+/-} 85.4 ml/s) and hemiellipsoidal (HE)-PISA (R = 0.91, bias -55.7 {+/-} 96.6 ml/s), while weaker correlations were observed for single plane 2D hemispherical (HS)-PISA with large underestimation (PLAX view: R = 0.71, bias -77.6 {+/-} 124.5 ml/s; A2Ch view: R = 0.69, bias -52.0 {+/-} 122.0 ml/s; A4Ch view: R = 0.82, bias -65.5 {+/-} 107.3 ml/s). For regurgitant volume (RV) quantification, integrated PISA presented improved accuracy over peak PISA for all PISA methods. For 3D-PISA, the bias in RV improved from -12.7 {+/-} 7.8 ml (peak PISA) to -2.1 {+/-} 5.3 ml (integrated PISA). ConclusionsIn FMR, conventional single plane 2D HS-PISA significantly underestimated MR, multiplane 2D PISA (HE-PISA and HC-PISA) improved the accuracy, and 3D-PISA is the most accurate. To better capture the dynamic feature of MR, integrated PISA using the sum of regurgitant flow rates is recommended.

PurposeUltrasound imaging of the gastrointestinal tract faces two major limitations: (1) lesions are often visible only momentarily, and (2) the lack of three-dimensional context makes it difficult to understand the orientation and anatomical location of the observed cross-sections. We aimed to develop a simple, semi-automated three-dimensional (3D) reconstruction method from routine ultrasound videos to enhance the visualization of transient lesions, particularly in the gallbladder. MethodsUltrasound videos of the authors own gallbladder polyps and the stomach were used. We proposed a stepwise process including video capture, frame extraction, pixel thresholding using both global and slice-specific values, and 3D volume rendering. The system was implemented using custom Python applications incorporating interactive threshold adjustment tools and PyVista-based 3D visualization. The workflow was tested using ultrasound videos of the gallbladder and stomach, with optional probe motion monitoring using an IMU sensor. ResultsThe method successfully reconstructed 3D representations of gallbladder polyps. The reconstructed images provided improved spatial understanding of the anatomical relationship between lesions and surrounding structures, which were originally visible only momentarily. ConclusionsThis approach may serve as an initial step toward practical 3D reconstruction from routine gastrointestinal ultrasound. Further refinement and clinical validation are necessary to establish its utility in daily clinical settings.

BackgroundMuscle activation is associated with increased tissue stiffness as measured by elastography in diagnostic applications. For this reason, we present ultrasound time-harmonic elastography (THE) applied to the vastus lateralis (VL) muscle during passive tonic vibration reflex (TVR) and active voluntary contraction (VC) stimulation to test whether TVR can serve as a stimulation method for functional assessment of skeletal muscle stiffness. MethodsTwenty-five asymptomatic volunteers (8 females, mean age 34 {+/-} 8 years) underwent five consecutive THE examinations of the VL at three VC loads (15, 22, and 37 N) and during TVR stimulation with 100 Hz frequency and 200 {micro}m (low) and 400 {micro}m (moderate) amplitude. Using standard line-by-line ultrasound, THE acquired the induced shear waves of 60, 70, and 80 Hz frequency with a frame rate of 100 Hz. Shear wave speed (SWS) was reconstructed as a proxy for muscle stiffness and statistically analyzed with repeated-measures ANOVA and nonparametric Friedman tests. ResultsSWS increased significantly from 1.66{+/-}0.11{square}m/s at rest to 1.79{+/-}0.12{square}m/s, 1.93{+/-}0.13 m/s, and 2.16{+/-}0.12 m/s with 15, 22 and 37 N VC load (p< 10-3). Similar effects were observed during TVR activation with increases to 1.93{+/-}0.13 m/s and 2.18{+/-}0.14 m/s for low and moderate TVR amplitudes (p < 10-3). Increase of SWS at moderate TVR amplitudes correlated with that of 37 N VC load (r = 0.67, p < 10-3). TVR-induced stiffness changes at 100 Hz vibration frequency and moderate amplitude can substitute the more subjective VC forces for muscle function testing. TVR stimulation combined with skeletal-muscle THE may be a useful tool for the routine clinical assessment of stiffness during muscle activation.

Abscesses are walled-off collections of infected fluids that often develop as complications in the setting of surgery and trauma. Abscess care depends on size, location, composition and complexity, among other patient factors. The goal of this work is to describe, using the latest ultrasound imaging technologies, the progression of abscess development in a porcine animal model. Intramuscular or subcutaneous injections of bacteria plus dextran particles as an irritant led to identifiable abscesses over a 2- to 3-week period. The abscesses were imaged at least weekly with B-mode, 3D B-mode, shear-wave elastography (SWE) and color flow imaging. Mature abscesses were characterized by a well-defined core of varying echogenicity surrounded by a hypoechoic capsule that was highly vascularized on Doppler imaging. Size and shape changes during development were quantified with 3D imaging. With SWE, the lesion stiffness varied interiorly and generally decreased over time. These ultrasound features potentially provide biomarkers to facilitate improved selection of treatment strategies for abscesses.

Pancreatic ductal adenocarcinoma (PDAC) remains one of the most lethal malignancies due to its dense stroma, which limits drug delivery and therapeutic efficacy. Ultrasound (US) mediated strategies using nanobubbles (NBs) offer a promising approach to enhance treatment, yet the biological effects of NB exposure and the timing of US application remain unclear. Here, we investigated how NB exposure with immediate (0h) or delayed (1h) US affects viability, proliferation, metabolism, and stress signaling in PANC-1 and BxPC-3 cells. Immediate US exposure in the presence of extracellular nanobubbles resulted in a greater reduction in cell viability at 24 h compared to delayed US application. Proliferation analysis showed that Ki67 positivity decreased following USNB treatments in both cell lines. Metabolically, NB treatment alone increased cellular activity, whereas combined USNB treatment reduced metabolic activity over time. Seahorse analysis revealed higher basal respiration in PANC-1 cells compared to BxPC-3 cells, consistent with a more glycolytic phenotype, while USNB treatment enhanced glycolytic responses, particularly in PANC-1. Moreover, stress responses were also more pronounced in PANC-1 cells, with HSP70 expression increasing up to 2-fold in NB incubated group and decreasing in USNB groups compared to untreated, whereas BxPC-3 cells exhibited only modest and opposite changes to PANC-1 in HSP70 expression decreasing with NB incubation. Treatment timing critically influenced outcomes, with immediate US producing stronger antiproliferative and cytotoxic effects, highlighting the importance of sequencing in USNB therapeutic strategies. Moreover, NBs alone stimulated metabolic and stress responses that may promote proliferation, whereas NBs combined with US induced stronger stress responses associated with metabolic reprogramming and reduced proliferation.

PurposeImaging of the central lymphatic system enables characterization of patient-specific lymphatic anatomy and accurate localization of leaks. Advancements in CT technology, particularly spectral CT, can enhance CT lymphangiography (CTL) with improved visualization and quantification. This study aimed to assess the feasibility of spectral CTL in both static and dynamic scans. Materials and Methods50% diluted iodinated contrast was injected into the bilateral superficial inguinal lymph nodes of a pig. The pig was scanned with a dual-layer spectral CT every 60 seconds for 10 minutes. To optimize contrast and visualize peristalsis, a second animal was injected with 25% and 10% diluted contrast and scanned dynamically 4 and 6.25 minutes after contrast injection. Conventional images and iodine maps were reconstructed to calculate the contrast-to-noise ratio (CNR). Additionally, the iodine density was measured adjacent to the lymphovenous junction to show fluctuations from peristalsis and contrast washout. ResultsIodine maps, compared to conventional images, separated the contrast-filled central lymphatic system from surrounding soft tissue and increased CNR to 895 compared to 43 with conventional images. 25% diluted contrast provided the best balance between visualization and quantification of the central lymphatic system, showing high and low iodine density regions corresponding to peristalsis. Iodine density peaked at 15.4 {+/-} 0.6 mg/mL and decreased to 2.0 {+/-} 0.1 mg/mL at 10.5 minutes. ConclusionSpectral CTL not only improves visualization of the central lymphatic system compared to CTL but also provides quantitative information for physiological characterization of lymphatic disease that can enhance current subjective assessment. Research highlights- Iodine maps from spectral CT lymphangiography separated contrast-filled lymphatic structures from surrounding soft tissue and provided better contrast-to-noise compared to conventional images. - Spectral CT lymphangiography enabled quantification of contrast in the central lymphatic system that demonstrated contrast washout and may be utilized for physiological characterization of disease. - Dynamic spectral CT imaging of the lymphatic system visually showed peristalsis in the thoracic duct and was further reflected in quantitative iodine density measurements.

Ultrasound has been used to target tumors either through local heating or local nanobubbles but these methods damage surrounding normal cells in the target area. Recent studies show that tumor cells are susceptible to mechanical stresses and undergo calcium-dependent apoptosis under conditions that promote normal cell growth. Here we report that low-frequency ultrasound causes apoptosis of tumor cells by activating a calpain-dependent mitochondrial pathway that depends upon calcium entry through the mechanosensitive Piezo1 channels. This is a general property of all tumor cell lines tested so far irrespective of tissue origin. In animals, ultrasound irradiation causes tumor killing in the chick chorioallantoic membrane (CAM) model with relatively little damage to the chick embryos. Further, patient-derived pancreatic tumor organoids are killed by ultrasound treatment. Because low-level ultrasound causes apoptosis of tumor cells from many different tissues in different microenvironments, it may offer a safe non-invasive approach to augment tumor treatments.

PurposeSkeletal muscle is commonly modeled as a transverse isotropic medium, however, the behavior of its anisotropy under active loading remains insufficiently characterized. In this study we used ultrasound time-harmonic elastography (THE) to quantify direction-dependent shear-wave speed (SWS) in the vastus lateralis (VL) muscle at rest and during low isometric contraction intensities. MethodsTwenty-six healthy adults (15 men, 11 women; 25.0 {+/-} 4.1 y) under-went multi-frequency THE (60-80 Hz). The transducer was aligned parallel (longitudinal) and perpendicular (transverse) to VL fascicles, and measurements were acquired at rest and at 15% and 30% of maximal voluntary contraction (MVC). The anisotropy index (AI) was defined as AI = SW S||/SW S{perp}. Orientation and contraction effects were tested with repeated-measures analyses. ResultsAt rest, longitudinal SWS exceeded transverse SWS (2.5 {+/-} 0.2 vs. 1.4 {+/-} 0.1 m/s; paired t-test p < 0.01). With contraction, SWS increased to 3.2 {+/-} 0.2 and 3.8 {+/-} 0.3 m/s (15%, 30% MVC) along fibers, and to 1.6 {+/-} 0.1 and 1.8 {+/-} 0.1 m/s across fibers (all p < 0.01). A two-factor repeated-measures ANOVA on SWS showed main effects of orientation and contraction and a significant interaction (all p < 0.01). AI increased from 1.7 {+/-} 0.1 at rest to 2.0 {+/-} 0.1 at 15% and 2.1 {+/-} 0.1 at 30% MVC (p < 0.01). No sex- or BMI-related effects were detected. ConclusionVL exhibited marked shear-wave anisotropy at rest that increased with low-level contraction intensities, indicating disproportionate stiffening along the fiber direction. THE provides a rapid, cost-effective, orientation-sensitive readout of muscle mechanics that may support studies of neuromuscular function and pathology.