Ultrasound in Medicine & Biology

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.

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.

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 [&ge;]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 [&ge;]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.

BackgroundVascular diseases like atherosclerosis or aortic aneurysms are common pathologies in the western world, promoting various, potentially fatal conditions. Hence, a plethora of animal models have been developed to investigate underlying mechanisms and potential therapeutics. Here we evaluate high resolution (HR) ultrasound in mouse models of atherosclerosis and abdominal aortic aneurysm (AAA) for noninvasive monitoring of morphological and functional vascular changes in vivo. MethodsEight-week-old ApoE-/- mice were used for disease models. For induction of atherosclerosis, mice were fed a western diet over 12 weeks. To trigger AAA development, osmotic minipumps were implanted, permanently releasing Angiotensin II continuously for 28 days. All animals were on C57Bl6/J background. HR vascular ultrasound of the carotid artery or the abdominal aorta was performed, respectively. Images obtained were analyzed by a speckle tracking algorithm (VevoVasc software) and were correlated with histological analyses by Picro Sirius Red staining and automated collagen quantification. ResultsArterial wall distensibility and global radial strain (GRS) as measures of arterial wall elasticity were reduced in the carotids of atherosclerotic mice as well as in the aortas of AAA mice. Pulse wave velocity (PWV) was elevated in both disease models. Intima-media thickness (IMT) was significantly increased in the atherosclerosis model. Matching those findings, area of the tunica media was enlarged in ApoE-/- mice fed a western diet, and in Angiotensin II treated mice as measured by automated image analysis, depicting higher collagen depositions in diseased arteries. Simple regression analysis revealed a strong correlation of media collagen content and area in AAA with IMT and GRS, respectively. In atherosclerosis, media collagen content significantly correlated with PWV and GRS, whereas wall distensibility was associated with the size of media area. ConclusionVascular imaging using latest generation HR ultrasound devices is suitable to trace changes of arterial wall properties in murine models of atherosclerosis and AAA. Obtained results not only correlate with histological findings but deliver information on functional parameters which may be used as early disease and risk markers in a longitudinal experimental approach.

BackgroundDistinguishing quiescent from rupture-prone atherosclerotic lesions has significant translational and clinical implications. Electrochemical impedance spectroscopy (EIS) characterizes biological tissues by assessing impedance and phase delay responses to alternating current at multiple frequencies. We evaluated invasive 6-point stretchable EIS sensors over a spectrum of experimental atherosclerosis and compared results with intravascular ultrasound (IVUS), molecular positron emission tomography (PET) imaging, and histology. MethodsMale New Zealand White rabbits (n=16) were placed on a high-fat diet for 4 or 8 weeks, with or without endothelial denudation via balloon injury of the infrarenal abdominal aorta. Rabbits underwent in vivo micro-PET imaging of the abdominal aorta with 68Ga-DOTATATE, 18F-NaF, and 18F-FDG, followed by invasive interrogation via IVUS and EIS. Background signal corrected values of impedance and phase delay were determined. Abdominal aortic samples were collected for histological analyses. Analyses were performed blindly. ResultsPhase delay correlated with anatomic markers of plaque burden, namely intima/media ratio (r=0.883 at 1 kHz, P=0.004) and %stenosis (r=0.901 at 0.25 kHz, P=0.002), similar to IVUS. Moreover, impedance was associated with markers of plaque activity including macrophage infiltration (r=0.813 at 10 kHz, P=0.008) and macrophage/smooth muscle cell (SMC) ratio (r=0.813 at 25 kHz, P=0.026). 68Ga-DOTATATE correlated with intimal macrophage infiltration (r=0.861, P=0.003) and macrophage/SMC ratio (r=0.831, P=0.021), 18F-NaF with SMC infiltration (r=-0.842, P=0.018), and 18F-FDG correlated with macrophage/SMC ratio (r=0.787, P=0.036). ConclusionsEIS with phase delay integrates key atherosclerosis features that otherwise require multiple complementary invasive and non-invasive imaging approaches to capture. These findings indicate the potential of invasive EIS as a comprehensive modality for evaluation of human coronary artery disease. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=118 SRC="FIGDIR/small/558681v1_ufig1.gif" ALT="Figure 1"> View larger version (18K): org.highwire.dtl.DTLVardef@1d02071org.highwire.dtl.DTLVardef@101ec0eorg.highwire.dtl.DTLVardef@130bff7org.highwire.dtl.DTLVardef@18b0955_HPS_FORMAT_FIGEXP M_FIG C_FIG HIGHLIGHTSO_LIElectrochemical impedance spectroscopy (EIS) characterizes both anatomic features - via phase delay; and inflammatory activity - via impedance profiles, of underlying atherosclerosis. C_LIO_LIEIS can serve as an integrated, comprehensive metric for atherosclerosis evaluation by capturing morphological and compositional plaque characteristics that otherwise require multiple imaging modalities to obtain. C_LIO_LITranslation of these findings from animal models to human coronary artery disease may provide an additional strategy to help guide clinical management. C_LI

The left ventricular (LV) end-systolic pressure volume relationship (ES; ESPVR) is the cornerstone of systolic LV function analysis. Recently, it became possible to measure 2D LV chamber shape during vena cava occlusion (VCO) with MRI. We used an improved level-set semi-automatic segmentation method (LSSM) to determine the effect of VCO on LV geometry, ES pressure area (PA) and ESPVR. 10 healthy adult sheep were anesthetized. LV pressure transducer and inferior vena cava (IVC) balloon catheter were percutaneously inserted. Ferumoxytol (0.125 ml/kg iv; AMAG Pharmaceuticals, Waltham, MA) was given to enhance blood pool contrast. LV pressure and 2D retrospectively-gated cine MRI of LV cross sections 25 (Apex), 50 (Mid) and 75% (Base) of the distance from the apex to the base of the LV were obtained during separate IVC balloon inflations (VCO). LV pressure was digitally filtered and LV chamber segmented with the LSSM. Cross sectional area, major and minor axes, major axis orientation, ESPAR and ESPVR were calculated. The LSSM had excellent reliability. All cross sections became more elliptical during VCO. The orientation (angle) of each major axis relative to the anterior RV insertion shifted during VCO. However, the orientation remained toward the septum. There was chamber collapse (LV area < 0.25 cm2) at the apical level during VCO (7 cases). ESPAR was non-linear at all levels. ESPVR was non-linear because of apical collapse. In conclusion, MRI-based measurement of LV geometry, ESPAR and ESPVR during VCO is a valuable method that may lead to improved understanding of systolic LV function. New and NoteworthyReal-time MRI was used to continuously measure the LV PA relationship as loading conditions were transiently varied in anesthetized sheep. All three examined cross-sections became more elliptical during VCO. The ESPAR were non-linear at all three cross-sections. Chamber collapse at the apical level during VCO resulted in a non-linear ESPVR. The heart contracted in a non-concentric manner during VCO which could inform modeling studies and elucidate mechanisms underlying LV adaptations to sudden load changes.

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

BackgroundBeside factors such as measurement technique, equipment accuracy, patient anxiety, race, ethnicity, ecological factors, diet (high sodium and calorie intake, and low potassium), physical inactivity, health conditions, and genetic vulnerability also influence blood pressure. Iodinated contrast agents (ICAs) or media (ICMs) are widely applied to improve the visibility of internal organs and other tissues in computed tomography (CT) and magnetic resonance imaging (MRI) procedures. ICAs have transient vasodilatory properties which can influence hemodynamic parameters immediately after administration during CT scans. Discrepancies on the effects of ICAs following their administration on hemodynamic parameters in adult patients who underwent contrast-enhanced CT (CECT) examinations have been reported in the literature. Anecdotal evidence further suggests that limited studies of the subject in Ghana. Knowledge of the relationship between hemodynamic parameters and contrast media is needed for prompt treatment, as well as the development of protocols to govern the administration of ICAs. AimThis study therefore evaluated HR, systolic blood pressure (SBP), and diastolic blood pressure (DBP) levels in adult patients following administration of non-ionic ICA during CECT examinations. MethodologySince data of the study variables were collected prospectively (before and after CT examinations) to determine SBP and DBP and HR levels following administration of non-ionic ICA during CT examinations, a prospective case-control study design was used, while a non-probability convenience sampling was employed to sample a population of 128 patients consisting of equal numbers of cases (experimental) and controls groups. Measurements of HR, SPB and DBP were made before and after the scans in both groups. Data analyses were done with Statistical Package for Social Sciences (SPSS) version 23. Pearson and Spearman correlations were used to compare the data variables obtained between the cases and control group. A p-value < 0.05 was considered statistically significant. ResultsThe measured mean values of HR, SBP and DBP were higher after contrast administration (HR=84.75{+/-}14.00 bpm; SBP =128.39{+/-}17.98 mmHg; DBP= 80.00 {+/-} 13.26 mmHg) than before (HR=82.56{+/-}15.08 bpm; SBP=120.81{+/-}14.32 mmHg; DBP=78.94{+/-}11.90 mmHg). There were insignificant differences between HR and SBP (p =0.716) and DBP (p = 0.533) prior to contrast media. The HR increase was statistically significant after contrast media (p=0.008). The mean differences in the HR, SBP, and DBP between genders were statistically insignificant after contrast administration. ConclusionsAdministration of non-ionic ICA increases HR but had no effects on SBP and DBP in both male and female adult patients who underwent diverse CECT examinations. The correlation statistics established no significant relationship between doses of contrast media and increases in the HR. No statistically significant differences between patient gender, BMI, and age on the hemodynamic parameters were found.

PurposeThis study compares two iodine-based contrast agents: iodine in ethanol (I2E) and aqueous solution of potassium triiodide (I2KI) in optimizing high-resolution, contrast-enhanced micro computed tomography imaging (micro-CT) of the cardiac conduction system (CCS) in porcine hearts. The study evaluates their relative efficacy in enhancing tissue contrast and anatomical delineation, aiming to improve CCS visualization for advanced cardiac research. MethodsDissected porcine hearts were stained with I2E or I2KI for contrast enhancement and scanned with micro-computed tomography. Signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and volumetric shrinkage were evaluated. Additionally, qualitative visualization of CCS-related anatomical landmarks, such as the sinoatrial node (SAN), atrioventricular node (AVN), and Purkinje fibres, was performed, along with assessment of artefact occurrence and sample integrity. The efficacy of the contrast agents was also determined by segmenting the regions of interest corresponding to the CCS from micro-CT images. These were then further validated against histology. ResultsI2E provided superior CNR, fewer artefacts, and preserved sample integrity, enabling smooth post-processing and histological sectioning. I2KI staining produced higher soft-tissue signal intensity and faster stain saturation (day 2) than I2E (day 3). However, I2KI exhibited leaching and introduced substantial staining artefacts. I2KI also exhibited structural disintegration, which, in turn, compromised downstream processing. ConclusionThese results suggest that I2E is a viable alternative to I2KI for CCS micro-CT imaging when sample preservation and downstream analyses are essential, whereas I2KI may be preferred for rapid, high-intensity staining where tissue integrity is less critical.

Background and aimsAtherosclerotic plaque rupture in the carotid artery can cause small emboli to travel to cerebral arteries, causing blockages and preventing blood flow leading to stroke. Contrast enhanced micro computed tomography (CECT) using a novel stain, phosphotungstic acid (PTA) can provide insights into the microstructure of the vessel wall and atherosclerotic plaque, and hence their likelihood to rupture. Furthermore, it has been suggested that collagen content and orientation can be related to mechanical integrity. This study aims to build on existing literature and establish a robust and reproducible staining and imaging technique to non-destructively quantify the collagen content within arteries and plaques as an alternative to routine histology. MethodsPorcine carotid arteries and human atherosclerotic plaques were stained with a concentration of 1% PTA staining solution and imaged using MicroCT to establish the in-situ architecture of the tissue and measure collagen content. A histological assessment of the collagen content was also performed from picrosirius red (PSR) staining. ResultsPTA stained arterial samples highlight the reproducibility of the PTA staining and MicroCT imaging technique used with a quantitative analysis showing a positive correlation between the collagen content measured from CECT and histology. Furthermore, collagen-rich areas can be clearly visualised in both the vessel wall and atherosclerotic plaque. 3D reconstruction was also performed showing that different layers of the vessel wall and various atherosclerotic plaque components can be differentiated using Hounsfield Unit (HU) values. ConclusionsThe work presented here is unique as it offers a quantitative method of segmenting the vessel wall into its individual components and non-destructively quantifying the collagen content withing these tissues, whilst also delivering a visual representation of the fibrous structure using a single contrast agent. Graphical Abstract O_FIG_DISPLAY_L [Figure 1] M_FIG_DISPLAY C_FIG_DISPLAY

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.

ObjectiveThe presence of atherosclerotic plaque components such as lipid rich necrotic core and intraplaque haemorrhage is associated with increased plaque vulnerability, and may be used to stratify the risk of future cerebrovascular events. Our aim was to investigate the relationship between selected carotid plaque components imaged with CTA, patient characteristics, and clinical outcomes. MethodsSymptomatic patients underwent carotid CTA as part of the BIOVASC study. Images were analysed for plaque volume composition with a semi-automatic Hounsfield Unit (HU)-based algorithm. Plaque components were classified based on their attenuation values: lipids <61 HU, fibrous tissue 61-129 HU and calcium >131 HU. Parametric and non-parametric tests were performed to compare plaque measurements to clinical characteristics and outcomes. ResultsOne-hundred and two symptomatic carotids were analysed (avg. age 69y, 54.9% Male, 29.4% severe stenosis). Mean plaque volume was 480{+/-}230 mm3, and the mean LRNC volume was 170{+/-}100 mm3. A difference in LRNC volume was identified between moderate and severe stenosis (190-150 mm3, p=0.012). Regression analysis showed that age and gender may predict increased plaque volume (p<0.001). A trend for reduced mean plaque LRNC was identified in patients receiving statins (130-210 mm3, p=0.08). Intra-reader reliability showed good agreement (0.62-0.78, p<0.001) between CTA plaque measurements. ConclusionsIn-vivo CTA plaque volume composition assessment is feasible with good intra-reader reliability. Our findings suggest that CTA-HU measurements may be used to provide improved mechanistic and diagnostic insights into atherosclerotic disease, and facilitate the quantification of selected plaque components whose presence may be associated with increased plaque vulnerability. Key PointsO_LIPlaque CTA Hounsfield Unit (HU) measurement and segmentation techniques can provide improved mechanistic and diagnostic insights into atherosclerotic disease. C_LIO_LIPlaque components characterisation using CTA HU measurements may help clinicians to identify patients presenting with high-risk vulnerable plaque. C_LIO_LICTA plaque volume composition assessment is feasible with good reliability observed between measurements taken at different time-points. C_LI

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.

BackgroundAbdominal Aortic Aneurysm (AAA) is a critical condition that can lead to fatal consequences if not detected and treated early. Despite the high prevalence in smokers and guideline recommendation for screening, AAA often remains undetected due to availability of diagnostic ultrasound examinations. This prospective clinical trial aimed to investigate the use of a Deep Learning (DL) algorithm to guide AAA screening. MethodsThis prospective, comparative diagnostic study was conducted at the Kaohsiung Chang Gung Memorial Hospital. We developed and deployed an object detection-based DL algorithm providing real-time guidance for novice users performing AAA screening using point of care ultrasound. 10 registered nurses with no prior ultrasonography experience were recruited and performed at least 15 scans on patients over 65 years old to acquire abdominal aorta videos. These scans were compared with those of physicians using the same ultrasound hardware but without DL guidance. ResultsA total of 184 patients (median [IQR] age of 72 [67-79], and 105 (57.1%) male) completed this study. The DL-guided novices achieved adequate scan quality in 87.5% (95% CI: 82.7 - 92.3%) of patients, comparable to the 91.3% (95% CI: 87.2-95.4%) rate of physician scans (p=0.310). This performance did not vary by BMI. The DL model predicted AAA with an AUC of 0.975, showing 100% sensitivity and 94.3% specificity. The DL model predicted the maximal width of abdominal aorta with mean absolute error of 2.8mm compared to physician measurements. 3 AAA with maximal width of aorta > 3cm were found in this study cohort. ConclusionDL-guided POCUS is an effective tool for AAA screening, providing comparable performance to experienced physicians. The use of this DL system could democratize AAA screening and improve access, thereby aiding in early disease detection and treatment. Clinical PerspectiveO_ST_ABSWhat is NewC_ST_ABSO_LIOur study presents a deep learning (DL) guidance system that enables novice users to perform Abdominal Aortic Aneurysm (AAA) screening with POCUS, yielding image quality comparable to experienced physicians. C_LIO_LIThe DL algorithm accurately identifies AAA from scans conducted by novice users, maintains consistent performance across patients with varying BMIs, and demonstrates increased scan efficiency with repeated use. C_LI Clinical ImplicationsO_LIDL-guided POCUS can potentially expand AAA screening capabilities to non-specialist settings and increase throughput for screening at risk individuals. C_LIO_LIThe implementation of our DL model for AAA screening could enhance early detection, particularly in underserved areas, but also optimize clinical workflows by decreasing diagnostic wait times and increasing ultrasound utilization efficiency. C_LI

BackgroundEchocardiographic texture analysis using the signal intensity coefficient (SIC) can identify fibrosis-associated microstructural changes. This approach has not been tested in immune-inflammatory disease states such as myocarditis or transplant rejection. MethodsRetrospective pilot analysis using the SIC was performed in populations including myocarditis (n=5), acute left anterior descending coronary artery STEMI (n=6), severe aortic stenosis with normal ejection fraction (n=7), ATTR amyloidosis (n=6), and cardiac transplant patients undergoing biopsy including patients with active rejection on histopathology (n=22), patients with history of rejection but no current rejection (n=15), and patients without history of or current rejection (n=5), and a healthy control group (n=28). ResultsDecreased SIC was noted in the myocarditis and transplant rejection populations, with decreasing SIC by presence and history of rejection. Consistent with prior literature, the SIC was elevated in cardiac conditions associated with fibrosis. ConclusionsThe SIC may be able to capture microstructural changes associated with immune-inflammatory processes such as cardiac transplant rejection and myocarditis.

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.

BackgroundThere is considerable focus on developing strategies for identifying subclinical cardiac decline prior to cardiac failure. Myocardial tissue elasticity changes may precede irreversible cardiac damage, providing promise for an early biomarker for cardiac decline. Biomarker strategies are of particular interest in cardio-oncology due to cardiotoxic effects of anti-neoplastic therapies, particularly anthracycline-based chemotherapeutics. Current clinical methods for diagnosing cardiotoxicity are too coarse to identify cardiac decline early enough for meaningful therapeutic intervention, or too cumbersome for clinical implementation. MethodsUtilizing changes in myocardial elasticity as a biomarker for subclinical cardiac decline, we developed a biomechanical model-based elasticity imaging methodology (BEIM) to estimate spatial maps of left ventricle (LV) myocardial elasticity. In this study, we employ this methodology to assess changes in LV elasticity in a non-human primate model of doxorubicin-induced cardiotoxicity. Cardiac magnetic resonance imaging of five African Green monkeys was acquired at baseline prior to doxorubicin administration, 6-weeks, and 15-weeks after final doxorubicin dose and histopathological samples of the LV were taken at 15-weeks after final doxorubicin dose. Spatial elasticity maps of the mid-short axis plane of the LV were estimated at each image acquisition. Global and regional LV elasticity were calculated and changes between imaging time points was assessed. LV elasticity at baseline and final time point were compared to cardiomyocyte size and collagen volume fraction measurements calculated from histopathological staining of archived tissue bank samples and study endpoint tissue samples utilizing Pearsons correlation coefficients. ResultsWe identify significant changes in LV elasticity between each imaging time point both globally and regionally. We also demonstrate strong correlation between LV elasticity and cardiomyocyte size and collagen volume fraction measurements. Results indicate that LV elasticity estimates calculated using BEIM correlate with histopathological changes that occur due to doxorubicin administration, validating LV elasticity solutions and providing significant promise for use of BEIM to non-invasively elucidate cardiac injury. ConclusionsThis methodology can show progressive changes in LV elasticity and has potential to be a more sensitive indicator of elasticity changes than current clinical measures of cardiotoxicity. LV elasticity may provide a valuable biomarker for cardiotoxic effects of anthracycline-based chemotherapeutics and cardiac disease detection.

BackgroundFocused ultrasound (FUS) is an emerging non-invasive technique for neuromodulation in the central nervous system (CNS). Functional ultrasound imaging (fUSI) leverages ultrafast Power Doppler Imaging (PDI) to detect changes in cerebral blood volume (CBV), which correlate well with neuronal activity and thus hold promise to monitor brain responses to FUS. ObjectiveInvestigate the immediate and short-term effects of transcranial FUS neuromodulation in the brain with fUSI by characterizing hemodynamic responses. MethodsWe designed a setup that aligns a FUS transducer with a linear array to allow immediate subsequent monitoring of the hemodynamic response with fUSI during and after FUS neuromodulation (FUS-fUSI) in lightly anesthetized mice. We investigated the effects of varying pressures and transducer positions on the hemodynamic responses. ResultsWe found that higher FUS pressures increase the size of the activated brain area, as well as the magnitude of change in CBV and could show that sham sonications did not produce hemodynamic responses. Unilateral sonications resulted in bilateral hemodynamic changes with a significantly stronger response on the ipsilateral side. FUS neuromodulation in mice with a cranial window showed distinct activation patterns that were frequency-dependent and different from the activation patterns observed in the transcranial model. ConclusionfUSI is hereby shown capable of transcranially monitoring online and short-term hemodynamic effects in the brain during and following FUS neuromodulation.

Background2D Quantitative Myocardial Perfusion (Qperf) MRI is limited by its inability to provide complete myocardial coverage within a heartbeat interval. This study developed and evaluated dual saturation multiband-accelerated Qperf imaging to achieve near-complete left ventricular coverage in free-breathing at an adequate in-plane spatial resolution, using a semi-automated Myocardial Blood Flow (MBF) framework for quantification deployable directly on the scanner console. MethodsA dual-saturation single-band QPerf sequence was modified for multiband imaging, enabling the acquisition of 6 high-resolution myocardial slices plus Arterial Input Function (AIF) during free-breathing. The technique was evaluated in 16 sedated pigs (13 healthy and 3 with LAD occlusion) under rest conditions on a 3T MRI scanner. Additionally, two healthy pigs underwent stress imaging as well. Statistical comparisons were performed between multiband and single-band MBF values in corresponding AHA segments. ResultsQualitatively, multiband QPerf provided superior left ventricular coverage and comparable image quality to single-band Qperf MBF maps, potentially enabling a more comprehensive detection of perfusion defects at rest. Quantitatively, multiband QPerf yielded lower MBF values than single-band QPerf (p < 0.01). However, Bland-Altman analysis (mean difference: -0.17 ml/min/g; 95% CI: -1.12 to 0.79 ml/min/g) and Passing-Bablok regression (intercept: -0.01 ml/min/g; 95% CI: - 0.37 to 0.28 ml/min/g) indicated that such discrepancy remained within the expected confidence intervals. Furthermore, the Passing-Bablok slope (0.88; 95% CI: 0.73-1.06) confirmed that mb-QPerf maintained sensitivity comparable to sb-QPerf in detecting perfusion changes under rest conditions. Finally, there was an overall increase in MBF values during stress vs rest conditions (average MBF Ratio 1.67 {+/-} 0.31) when comparing healthy pigs. ConclusionMultiband-accelerated Qperf is feasible, providing improved left ventricular coverage, adequate in-plane resolution, and a semi-automated MBF quantification framework directly on the scanner console. Compared to its single-band counterpart, multiband QPerf demonstrated a more comprehensive visualization of perfusion defects and comparable sensitivity and accuracy in detecting perfusion changes at rest. Further research and clinical validation in patient populations are needed to confirm its utility in the diagnosis of coronary artery disease.