High-frequency quantitative ultrasound (QUS) offers a promising approach to characterize soft tissue microstructure ex vivo. In this study, we evaluated its ability to detect histological tendon changes in a murine model of patellar tendinopathy. Collagenase was injected into the patellar tendon of C57BL/6 J mice to induce tendinopathy. Tendons were scanned ex vivo using a 60-MHz transducer to acquire radiofrequency (RF) ultrasound echo data. QUS parameters based on envelope statistics and backscatter coefficient measurements were computed from the RF data. Additionally, tendon thickness was measured from the B-mode images. QUS parameters were compared between control and collagenase-injected groups. Histological sections were evaluated using a modified Movin score. Significant differences were observed in QUS parameters effective scatterer diameter (ESD), the Homodyned-K parameter α $\alpha $ , and thickness between control and collagenase-injected groups (p < 0.05 for all). ESD and thickness correlated with histological scores (R = 0.50, p < 0.001 for both), and receiver operating characteristic analyses showed high classification accuracy (AUC = 0.82-0.89). These findings indicate that QUS parameters are sensitive to pathological alterations in tendon microstructure and may serve as surrogate markers of structural integrity. As a rapid, cost-effective, and portable imaging modality, QUS holds strong potential for longitudinal monitoring of tendinopathy and evaluating treatment response in both animal models and clinical settings. Statement of Clinical Significance: QUS parameters detected tendon microstructural changes, indicating potential for non-invasive longitudinal monitoring, although limited here to post-mortem imaging.

Metabolic dysfunction-associated steatohepatitis (MASH) is a disease characterized by accumulation of fat droplets and fibrous tissue in the liver. This disease has attracted attention due to its high incidence and risk of severe complications. High-frequency quantitative ultrasound (QUS) has demonstrated strong potential in the diagnosis of liver diseases. However, previous studies focused only on evaluating lipid droplets in fatty liver, without accounting for the interference of other components such as fibrous tissue. This study aimed to clarify the scattered signals from various tissues by analyzing six numerical computer phantoms simulating normal liver, fatty liver and hepatitis, using an amplitude envelope statistical method, the double Nakagami (DN) model. The simulation system consisted of an ultrasound platform and a linear probe with center frequency of 31.25 MHz. Eleven plane waves ranging from-15 degrees to +15 degrees were transmitted and received using a compound plane-wave imaging method. The results show that the DN model matches the amplitude envelope of the original echo signals and effectively distinguishes independent signal components arising from different tissues. In fatty liver phantoms, the DN model parameter awF showed a strong positive correlation (r = 0.8434, p = 0.0472) with fat volume. In hepatitis phantoms, awF increased with increase in the fibrous tissue mixture ratio in the regions of interest, while uL, uF were close to 1, reflecting the cell distribution patterns and tissue characteristics. These results indicate that echo signals exhibit different properties when the scatterer density is high or when scattering intensity is strong, supporting the feasibility of using the DN model to differentiate fat and fibrous tissues from normal liver. However, real clinical cases are more complex, as fatty and fibrous tissue intermix in the liver, requiring further validation in the future. Nevertheless, the results show the potential of this method for real-time, noninvasive quantitative characterization of tissue properties.

Objectives/Goals: To translate quantitative ultrasound (QUS) from imaging biophysics into clinical dermatology by evaluating its reproducibility, diagnostic differentiation, and potential as a noninvasive, point-of-care tool for nail disease assessment. Methods/Study Population: Diagnosing nail disease is difficult due to overlapping features and the invasiveness of biopsy. In a prospective study (recruitment ongoing), patients with onychomycosis, inflammatory nail disease (psoriasis or lichen planus), and controls underwent 15-MHz ultrasound of fingernails and toenails (n = 26 patients, 152 nails). Raw radio-frequency data were processed to derive three QUS parameters: Homodyned-K [α] (microstructural organization), effective scatterer diameter (ESD) (scatterer size reflecting tissue texture), and effective acoustic concentration (EAC) (scatterer density reflecting compactness). Metrics were analyzed with t-tests and mixed-effects models. Within-patient consistency and parameter reproducibility were evaluated to assess clinical translation feasibility. Results/Anticipated Results: Diseased fingernails (33 vs 54 controls) showed reduced α (−1.11, p < 0.001), reflecting loss of microstructural organization. Onychomycosis had the largest change (−1.25), while inflammatory nails were moderately reduced (−0.93). ESD showed opposite trends (+0.85, p = 0.02) indicating coarser scatterers in fungal disease, and EAC was uniquely elevated in lichen planus (+1.30, p < 0.01), consistent with fibrotic regions. In the toenail cohort (16 diseased vs 49 controls), onychomycosis showed parallel changes (α −0.9, p < 0.001; ESD +1.0, p = 0.02), supporting reproducibility across nail sites. Findings were confirmed by mixed-effects models. Together, these parameters quantify disease-specific microstructure and demonstrate technical and biological feasibility for clinical translation. Discussion/Significance of Impact: QUS provides interpretable biophysical markers that differentiate fungal, inflammatory, and fibrotic nail diseases. By bridging imaging physics with clinical diagnosis, QUS offers a scalable, noninvasive approach for point-of-care dermatologic imaging and advances the translation of QUS into practice.

Quantitative ultrasound (QUS) is widely used for non-invasive evaluation of fatty liver due to its ability to characterize tissue acoustic properties. Accurate characterization requires an integrated understanding of tissue properties seamlessly spanning from the organ to the cellular level. Metabolic dysfunction-associated steatohepatitis (MASH) involves complex structural changes, including lipid droplet accumulation and fibrosis, which influence acoustic responses. This study aims to establish a foundational evaluation method for fatty liver by investigating the impact of structural components on acoustic properties across a broad frequency range (5–100 MHz) using QUS. Rat liver models representing various stages of steatosis and MASH, confirmed by histopathology, were analyzed. Broadband ultrasonic measurements with single-element transducers allowed calculation of frequency-dependent sound speed and attenuation. Electrical properties, such as conductivity and permittivity measured over 1 kHz–1 MHz, were also assessed to provide complementary insights into tissue composition and structure. By leveraging wideband ultrasonic data, this study contributes to building a multilayered evaluation framework that captures tissue structure from macro to micro scales. The integrated acoustic and electrical analysis advances the understanding of physical relationships in fatty liver, supporting future development of non-invasive diagnostic techniques for MASH and related conditions.

With aging and progression of diseases such as myopia, vitreous undergoes fibrous liquefaction into gel and liquid components with opaque fibers and nodules. The molecular changes that form inhomogeneities in the vitreous body induce a disturbing visual phenomenon called Vision Degrading Myodesopsia (VDM) (i.e., “floaters”). Our past studies demonstrated that FDA approved, 15- and 20-MHz B-mode ophthalmic ultrasound (US) was very effective for quantifying vitreous echodensity (i.e., inhomogeneity) using quantitative US (QUS) methods based on B-mode log-compressed envelope data. We demonstrated a direct, probably causal relationship between the degree of vitreous echodensity and VDM’s impact on vision and quality of life. We found positive correlations between QUS and degradation in contrast sensitivity (CS) and unhappiness as assessed with the NEI-VFQ (Visual Function Questionnaire); that in myopia, QUS and CS worsened in eyes with PVD and longer axial lengths; that QUS and CS increased with PVD and age; that QUS and CS increased in eyes with PVD versus eyes without PVD; and that PVD induced increased QUS and CS, prospectively. Recently, we implemented a more rigorous QUS approach using the raw radiofrequency data and Double Nakagami envelope statistics to separate the noise and improve QUS analysis of vitreous echodensities.

Cancerous breast lesions can induce localized microstructural changes in adjacent white adipose tissue (WAT), altering adipocyte size and number density. Current methods for assessing changes in WAT are inherently invasive. We hypothesize that quantitative ultrasound (QUS) methods based on backscatter coefficient (BSC) are sensitive to cancer-related microstructural alterations in WAT. Female subjects (N = 112, mean age 54 ± 16) scheduled for ultrasound-guided core needle biopsy of lesions categorized as BIRADS ≥4b were recruited. Radiofrequency (RF) echo data of each lesion were acquired using a GE Logiq E10 scanner with an ML6-15 probe (9 MHz center frequency). Two QUS parameters, effective scatterer diameter (ESD) and effective acoustic concentration (EAC), were computed from RF echo data using a reference phantom method. Parameters were analyzed within the lesion, in WAT ≤4 mm from the lesion edge, and in WAT > 4 mm away. ESD was higher near malignant lesions (p = 0.02) compared to benign, with no differences in distant WAT. Moreover, malignant tumors showed higher ESD (p = 0.004) and lower EAC (p = 0.003) compared to benign lesions. A support vector machine operating only on lesion-adjacent WAT parameters achieved area under the ROC of 0.72 for differentiating benign and malignant tumors. These findings suggest QUS is sensitive to cancer-related microstructural properties of WAT and may provide an effective means for characterizing adipocytes non-invasively and in-vivo. [Work supported by NIH Grant R21EB035809 (CH).]

OBJECTIVE:Quantitative ultrasound (QUS) methods were applied to detect changes in placental microstructure in the reduced uterine perfusion pressure (RUPP) model of preeclampsia in rats. Preeclampsia is a life-threatening pregnancy disorder associated with abnormal placental development that is inadequately treated and managed. METHODS:Nine timed-pregnant Sprague-Dawley rats were used in this study. On gestational day 14 (GD 14), five rats received RUPP surgery to induce preeclampsia. US radiofrequency data were acquired for QUS analysis on GD18. On GD19, animals were sacrificed and dissected to acquire placental tissue samples. The cell nuclear diameter in each anatomical layer of the placenta was measured to compare with regional effective scatterer diameter (ESD) values. RESULTS:ESD measurements obtained using in vivo QUS imaging correlated well (R2 = 0.58, p = 3.8e-6) with cell nucleus diameter measurements from microscopy images. RUPP placentas had significantly smaller junctional zones compared to control placentas (p = 0.013). The average ESD in RUPP placentas was 1.0 µm smaller compared to control placentas (p = 0.040). This decrease in ESD in RUPP placentas is consistent with the decreased size of the junctional zone, which, in comparison to the labyrinth zone and chorionic plate, has larger cell nuclei (p = 3.3e-21 and p = 9.5e-27, respectively) and larger ESD (p = 5.6e-4 and p = 4.5e-8, respectively). CONCLUSION:These results demonstrate the potential of QUS as a non-invasive tool for detecting critical changes in placental microstructure, improving maternal and fetal outcomes by enabling earlier diagnosis and more timely therapeutic interventions in preeclampsia.

High myopia increases the risk of irreversible vision loss and is associated with changes in scleral collagen microstructure. While refractive error (RE) measurements assess current myopia severity, they cannot predict progression. We developed a high-frequency (80 MHz) point-of-care (POC) ultrasound instrument to collect radiofrequency (RF) echo data of the anterior sclera in vivo and applied quantitative ultrasound (QUS) techniques to compute parameters related to tissue microstructure. In this study, we investigated the feasibility of QUS to predict myopia progression. Longitudinal RE and POC measurements from 59 subjects were collected at baseline and annually for 2 years. QUS parameters based on backscatter coefficient (BSC) and shear wave speed were computed from years 0 and 1. Eyes with change in RE (ΔRE) ≥0.5D from baseline were classified as progressors. After 1 year, the 18 progressor eyes exhibited statistically significant changes in QUS parameters (ΔQUS, p ≤ 0.01), whereas non-progressor eyes showed no significant ΔQUS. Multilinear regression showed strong correlation between ΔQUS and 1-year ΔRE (R = 0.82, p < 0.001). Combining ΔQUS with baseline ophthalmic measurements, a logistic regression classifier predicted 2-year progressor eyes with AUC = 0.75. These findings support high-frequency QUS as a tool to detect myopia-induced changes in anterior sclera microstructure and predict myopia progression. [Work supported by NIH grant R21EB028084 (JM).]

BACKGROUND:Ultrasound imaging is a valuable diagnostic tool, but quantifying tissue characteristics can be challenging. While models like the Nakagami distribution help characterize tissue microstructure based on envelope statistics, they may not fully capture the complexity of tissues with multiple scatterer types. PURPOSE:This study aims to develop and validate an enhanced version of the Double Nakagami Distribution (DND) model using moment equations for quantitative ultrasound imaging. We seek to establish its theoretical foundation and demonstrate its effectiveness through numerical simulations and experimental results. METHODS:Five versions of the DND estimation model were developed to compute the five associated model parameters. Using the method of moments, the estimators directly computed 5, 4, or 3 DND parameters with any remaining parameters derived from statistical relationships. After selecting the initial solution for the DND methods, Monte Carlo simulations were employed to generate random combinations of Nakagami parameters within two-scatterer media. For experimental validation, four phantoms with different mixtures of nylon and acrylic scatterers were used. Ex vivo validations were conducted using radio-frequency data from four excised fatty rat livers, each exhibiting low and high concentrations of fat droplets. The median and interquartile range of error values from numerical simulations were analyzed, and the Kruskal-Wallis test was used to assess statistical differences, with post hoc Dunn tests with Bonferroni correction for pairwise comparisons. Effect sizes were calculated using Cohen's d to quantify improvements in fitting performance. RESULTS:The DND estimation model with three parameter estimations demonstrated the least computation time (p < 0.05) and was identified as the most robust of the proposed DND models for further assessments. In simulations with 106 independents, identically distributed random data points, the errors of all five DND parameters remained below 5%. Our results indicated that increasing the mode ratio of the two scatterers' probability density function histograms enhanced the model's performance. In in vitro phantoms, the DND method estimated the scatterer mixture ratios with errors of less than 6%. Additionally, the DND estimation model exhibited lower Kullback-Leibler divergence (KLD) values compared to the Single Nakagami Distribution (p < 0.0001), indicating that DND provided a superior fit. The effect sizes were consistently large (d > 0.8), further supporting the improved performance of DND. CONCLUSIONS:A DND estimation model of envelope statistics with estimations of three parameters was the most robust method regarding computation speed, KLD values, and accuracy.

The single Nakagami distribution (SND) models backscatter envelope statistics for tissues with a single type of scatterer but is less effective for tissues containing multiple scatterer types. This study introduces a new Double Nakagami distribution (DND) estimator to model tissues with two types of scatterers. The DND model directly estimates three parameters corresponding to number density and relative volume ratio of the first scatterer type, from which two additional parameters corresponding to the second scatterer type are derived through a method-of-moments approach. An algorithm was developed for efficient model initialization. To validate the method, simulations were conducted by generating envelope statistics data with various combinations of the five DND parameters. Experimental data were also collected from agar phantoms containing varying concentrations of nylon and acrylic spheres. The simulations showed the DND model parameter estimation was more accurate than the SND model with errors below 5%. For the phantom tests, the DND model accurately estimated scatterer proportions with errors below 6%. The DND fit model demonstrated significant advantages in terms of computational accuracy for tissues containing more than one type of scatterer. The DND model has the potential to improve quantitative tissue characterization when there are multiple scatterer types.

PURPOSE:To manage clinically significant vitreous floaters, called vision degrading myodesopsia, using objective quantification of vitreous structure and visual function, in order to distinguish cases that can be observed (OBS) from those that merit surgery, and define the profile of OBS patients. DESIGN:Retrospective nonrandomized interventional clinical study. SUBJECTS:There were 651 eyes in 393 patients (220 men and 173 women; aged 57.3 ± 14.7 years) with the chief complaint of floaters. Etiologies were posterior vitreous detachment (PVD; 252 of 651, 38.7%), myopic vitreopathy (MV; 133 of 651, 20.4%), and combined PVD + MV (210 of 651, 32.3%). METHODS:OBS alone was performed in 362 cases. Sutureless 25-gauge limited refractive vitrectomy (LRV) without surgical PVD was performed in 289 eyes. MAIN OUTCOME MEASURES:Vitreous echodensity was measured by quantitative ultrasonography, contrast sensitivity (CS) with Freiburg Acuity Contrast Testing (%W); patient-reported outcomes with NEI Visual Function Questionnaire 25 (VFQ-25). RESULTS:OBS was chosen in 362 of 651 (55.6%; mean age 55.0 years), and LRV was elected in 289 of 651 (44.4%; mean age 60.1 years). Observation cases had 43.7% less vitreous echodensity (688 ± 170 AU vs. 1222 ± 356 AU; P < 0.0001), 35.7% better CS (2.90%W ± 1.33%W vs. 4.51%W ± 1.56%W; P < 0.0001), and better VFQ-25 (79.2 ± 6.0 vs. 77.2 ± 5.2; P < 0.01). Subjects initially choosing OBS who converted to surgery >1 year later had comparable CS to the OBS group at study entry, which worsened before electing LRV. Postoperatively, echodensity decreased by 59.6% (to 494 ± 64 AU, P < 0.0001), CS improved by 45.7% (to 2.45 ± 1.12%W, P < 0.0001), and VFQ-25 improved by 6.3% (to 82.0 ± 9.0, P < 0.0001). Sequelae of LRV included vitreous hemorrhage (0.7%), retinal tears (2.8%), retinal detachment (2.4%), macular pucker surgery (1.4%), recurrent floaters (5.2%), and cataract surgery (35.8%; average age = 62.7 ± 6.7 years, on average 23.7 months post-vitrectomy; below age 50 only 3 of 37 (8.1%) underwent cataract surgery [average follow-up = 28.9 months for all 37 patients]). CONCLUSIONS:Patients with vision degrading myodesopsia from vitreous floaters can be managed by OBS or vitrectomy. Objective quantitative measures of vitreous echodensity and CS aid patient selection for OBS. These patients were younger and phakic, had floaters from myopic vitreopathy without PVD, and had less vitreous echodensity, as well as better CS. FINANCIAL DISCLOSURE(S):Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Structural changes in myocardial tissue, such as fibrosis and necrosis, contribute to cardiac remodeling and dysfunction. Histological analysis remains the gold standard for assessing these changes but is invasive. In this study, we demonstrate a non-invasive approach using quantitative ultrasound (QUS) with ultrafast imaging to characterize myocardial microstructure in a murine model of heart failure. A cardiomyocyte-specific Tafazzin knockout (TAZ-cKO) mouse model of dilated cardiomyopathy was used, alongside healthy controls (3 KO, 5 control mice). Ultrafast plane-wave image data were acquired over two full cardiac cycles from the left ventricular parasternal long-axis view. Data were acquired using a Verasonics Vantage NXT system and a 28-MHz linear array transducer, with three tilted plane waves (−7.5°, 1°, 7.5°) at an effective frame rate of 8 kHz. Ten coherently compounded frames during diastole per cardiac cycle were temporally concatenated to improve QUS spectral analysis. The QUS parameter of effective scatterer diameter (ESD) was calculated from the backscatter coefficient using a Gaussian model and reference phantom method. The results showed significantly larger ESD in KO mice compared to controls (p = 0.02), indicating QUS was effective to non-invasively detect myocardial microstructural changes, which may have future clinical utility in cardiac diagnostics.

OBJECTIVE:We characterize rat placenta microstructure in the context of the reduced uterine perfusion pressure (RUPP) model of preeclampsia using the homodyned K-distribution to parameterize envelope-detected signals of ultrasound radiofrequency echo frames obtained in vivo. Preeclampsia is a life-threatening pregnancy syndrome related to abnormal placental tissue microstructure which motivated the quantitative ultrasound-based tissue characterization approach used in this study. METHODS:Ultrasound radiofrequency echo frames against time (or videos) were obtained on 30 and 38 in vivo placentae at gestation day (GD) 14 and 18 respectively, using 9 Sprague-Dawley rats. Preeclampsia-like effects were induced by surgical modification (post GD 14) following the RUPP model, giving a total of 20 RUPP and 18 control placentae at GD 18. The homodyned K-distribution was fit to value distributions of envelope-detected signals of ultrasound radiofrequency echo frames against time, yielding temporal α (scatterer number per resolution cell) and κ (ratio of coherent to diffuse signal power) parameters used to characterize the placental tissue microstructure. RESULTS:Visualization of GD 18 α values as a color overlay on B-mode ultrasound video suggested higher values of control compared with RUPP. The mean kurtosis for RUPP was 4.07 ± 0.71 in comparison to 5.08 ± 1.28 for the control using placenta-level kurtosis values (p = 0.0044). There were no significant differences observed in GD 14 placentae, consistent with expectations. Further, we visualized and quantified temporal changes in GD 18 α values with frame-level statistics that support earlier findings. CONCLUSIONS:This study quantitatively characterizes rat placenta microstructure using the homodyned K-distribution and temporal α and κ parameters.