Browsing by Autor "Emilio J. Ochoa"

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Automated Analysis of Fetal Heart Rate from VSI-Based Ultrasound Using Segmentation-Guided Optical Flow
(2025) Emilio J. Ochoa; Luis C. Revilla; Stefano E. Romero; Anna Jarvis; Alvin Wei Ze Chew; M. A. Peterson; Marika Toscano; Thomas J. Marini; María Helguera; Benjamín Castañeda
Volume Sweep Imaging (VSI) enables standardized obstetric ultrasound acquisition by non-experts in low-resource settings; helping to the assessment of diverse fetal variables. While Doppler is used to detect fetal heart changes; due to the limited constraints is not possible to apply this method, and VSI has not yet been applied for fetal heart rate (FHR) measurement without Doppler capability. This study proposes a segmentation-guided optical flow method to estimate FHR from VSI-based B-mode cine-loops. Third-trimester VSI sweeps where fetal heart was visible were manually segmented frame-by-frame by a physician. Dense optical flow was computed within the heart mask, and the mean motion angle over time was bandpass-filtered (90–200 BPM) with variable Butterworth order. A confidence score (1–5) was proposed based on the filter order that was correlated to the quantity of frames with visible heart. Out of 114 cine-loops analyzed, all clips with confidence score ≤ 3 (n=49) were non-measurable by both the algorithm and physicians. Among high-confidence clips (≥ 4; n=65), 18 were excluded due to incomplete heart visualization, leaving 47 for Bland–Altman analysis. The mean bias was −8.63 BPM with 95% limits of agreement [−52.26,69.52] BPM and no statistically significant difference (p > 0.05). These findings demonstrate the feasibility of integrating automated FHR estimation into existing VSI obstetric protocols without Doppler, enabling functional cardiac assessment in settings with limited access to specialized sonography.
First Exploration of H-scan Ultrasound Imaging in Diabetic Foot: A Feasibility Study
(2025) Emilio J. Ochoa; Gilmer Flores Barrera; Cristina Orihuela; Itamar Salazar-Reque; Stefano E. Romero; Roozbeh Naemi; Kevin J. Parker; Benjamín Castañeda
Diabetic foot complications are a leading cause of morbidity and lower-limb amputation worldwide, largely driven by structural and mechanical alterations of plantar soft tissues. Reverberant shear wave ultrasound elastography has shown potential in detecting increased stiffness in diabetic plantar tissue; however, stiffness alone does not fully capture microstructural remodeling at the scatterer level. H-scan ultrasound imaging is a scatterer-size–sensitive technique that encodes frequency-dependent backscatter information into color maps, providing a novel means of assessing tissue microarchitecture. In this feasibility study, we applied H-scan imaging to the plantar soft tissues of 10 diabetic patients and 3 healthy controls. Radiofrequency ultrasound data were acquired at clinically relevant sites (1st and 3rd metatarsal heads and heel), processed using a 256-filter Gaussian convolution algorithm, and analyzed with an automated region-of-interest detection method. The intensity-weighted percentage of red pixels (IWP<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">red</inf>), representing the prevalence of larger scatterers, was extracted as a quantitative biomarker. Results showed significantly higher IWP<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">red</inf> values in participants with diabetes at the 3rd metatarsal head for both feet (left: p ≤ 0.002, right: p ≤ 0.001), while no significant differences were observed at the 1st metatarsal head or heel. These findings suggest that H-scan imaging can detect microstructural alterations in diabetic plantar tissues, particularly at high-risk ulceration sites. This study provides the first evidence supporting the feasibility of H-scan ultrasound as a non-invasive, rapid, and clinically deployable tool for diabetic foot risk assessment.