Journal of Biomedical Optics最新文献

{"title":"Development and characterization of a combined fluorescence and spatial frequency domain imaging system for real-time dosimetry of photodynamic therapy.","authors":"Alec B Walter, E Duco Jansen","doi":"10.1117/1.JBO.30.S3.S34103","DOIUrl":"10.1117/1.JBO.30.S3.S34103","url":null,"abstract":"<p><strong>Significance: </strong>Current methods of measuring dosimetry for photodynamic therapy (PDT) have proven to be inadequate in their inability to provide accurate, real-time, and spatially resolved monitoring without interrupting the PDT treatment.</p><p><strong>Aim: </strong>Our goal was to develop and validate a combined treatment and dosimetry system capable of monitoring implicit and explicit dosimetry in real time during non-contact PDT.</p><p><strong>Approach: </strong>By employing both fluorescence imaging and spatial frequency domain imaging (SFDI), designed with low-cost, off-the-shelf components, the combined imaging system would be able to provide information on the spatial distributions of photosensitizer concentrations, tissue oxygenation, and delivered light dose, all while monitoring the photobleaching dynamics of the photosensitizer. Although the concept behind the combined system is not specific to any one photosensitizer, we focused on designing the system for the endogenous PDT of Gram-positive bacteria which utilizes coproporphyrin III as the photosensitizer.</p><p><strong>Results: </strong>The overall performance of the system was assessed, with the accuracy, precision, and resolution of the SFDI-derived optical property maps being determined to fall within comparable ranges to other systems, despite the <math><mrow><mn>1.0</mn> <mtext> </mtext> <msup><mrow><mi>mm</mi></mrow> <mrow><mo>-</mo> <mn>1</mn></mrow> </msup> </mrow> </math> spatial frequency utilized for the shorter wavelengths. After validating the ability of the system to correct for tissue-like optical properties, and thus produce accurate quantitative fluorescence images, a preliminary assessment of antimicrobial PDT photobleaching dosimetry was performed, and high correlations were found between the fluorescence and PDT outcomes.</p><p><strong>Conclusions: </strong>Overall, the developed imaging system showcases the potential to enable a more thorough analysis of PDT dosimetry and the impact of different variables on treatment outcomes.</p>","PeriodicalId":15264,"journal":{"name":"Journal of Biomedical Optics","volume":"30 Suppl 3","pages":"S34103"},"PeriodicalIF":3.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12118877/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144181697","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Toward fluorescence digital twins: multi-parameter experimental validation of fluorescence Monte Carlo simulations using solid phantoms.","authors":"Mayna H Nguyen, Ethan P M LaRochelle, Edwin A Robledo, Alberto J Ruiz","doi":"10.1117/1.JBO.30.S3.S34104","DOIUrl":"10.1117/1.JBO.30.S3.S34104","url":null,"abstract":"<p><strong>Significance: </strong>As fluorescence-guided surgery (FGS) gains clinical adoption, robust and experimentally validated computational models for tissue fluorescence are increasingly essential. Although there have been several developments in modeling fluorescence with Monte Carlo simulations, the scope of the experimental validation has been limited in the parameters tested and phantoms used.</p><p><strong>Aim: </strong>We aim to present and experimentally validate a graphics processing unit (GPU)-accelerated, voxel-based Monte Carlo fluorescence framework capable of modeling varying fluorophore concentrations, optical properties, and complex three-dimensional (3D) geometries.</p><p><strong>Approach: </strong>A two-step approach (MCX-ExEm) based on Monte Carlo eXtreme was developed for simulating fluorescence. Both commercial reference targets and custom 3D-printed phantoms with well-characterized optical properties were imaged for varying parameters-including absorption, scattering, fluorophore concentrations, and geometries-and compared against simulations.</p><p><strong>Results: </strong>Strong agreement is observed between simulated and experimental fluorescence across all tested parameters. MCX-ExEm accurately captures nonlinear quenching at high fluorophore concentrations, variations driven by scattering and absorption, intensity scaling with volume, and depth-dependent attenuation and resolution. Minor deviations occur primarily under low-scattering or low-absorption regimes, where optical characterization presents greater uncertainties.</p><p><strong>Conclusions: </strong>By integrating experimentally validated simulations with a broad range of solid phantoms, this framework establishes a foundation for developing fluorescence digital twins, enabling faster and more systemic testing of fluorescence imaging systems. These findings can help accelerate the design and optimization of FGS and other fluorescence-based biomedical applications.</p>","PeriodicalId":15264,"journal":{"name":"Journal of Biomedical Optics","volume":"30 Suppl 3","pages":"S34104"},"PeriodicalIF":3.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12119851/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144181833","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reduction of photobleaching effects in photoacoustic imaging using noise agnostic, platform-flexible deep-learning methods.","authors":"Avijit Paul, Christopher Nguyen, Tayyaba Hasan, Srivalleesha Mallidi","doi":"10.1117/1.JBO.30.S3.S34102","DOIUrl":"10.1117/1.JBO.30.S3.S34102","url":null,"abstract":"&lt;p&gt;&lt;strong&gt;Significance: &lt;/strong&gt;Molecular photoacoustic (PA) imaging with exogenous dyes faces a significant challenge due to the photobleaching of the dye that can compromise tissue visualization, particularly in 3D imaging. Addressing this limitation can revolutionize the field by enabling safer, more reliable imaging and improve real-time visualization, quantitative analysis, and clinical decision-making in various molecular PA imaging applications such as image-guided surgeries.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Aim: &lt;/strong&gt;We tackle photobleaching in molecular PA imaging by introducing a platform-flexible deep learning framework that enhances SNR from single-laser pulse data, preserving contrast and signal integrity without requiring averaging of signals from multiple laser pulses.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Approach: &lt;/strong&gt;The generative deep learning network was trained with an LED-illuminated PA image dataset and tested on acoustic resolution PA microscopy images obtained with single-laser pulse illumination. &lt;i&gt;In vitro&lt;/i&gt; and &lt;i&gt;ex vivo&lt;/i&gt; samples were first tested for demonstrating SNR improvement, and then, a 3D-scanning experiment with an ICG-filled tube was conducted to depict the usability of the technique in reducing the impact of photobleaching during PA imaging.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Results: &lt;/strong&gt;Our generative deep learning model outperformed traditional nonlearning, filter-based algorithms and the U-Net deep learning network when tested with &lt;i&gt;in vitro&lt;/i&gt; and &lt;i&gt;ex vivo&lt;/i&gt; single pulse-illuminated images, showing superior performance in terms of signal-to-noise ratio ( &lt;math&gt;&lt;mrow&gt;&lt;mn&gt;93.54&lt;/mn&gt; &lt;mo&gt;±&lt;/mo&gt; &lt;mn&gt;6.07&lt;/mn&gt;&lt;/mrow&gt; &lt;/math&gt; , and &lt;math&gt;&lt;mrow&gt;&lt;mn&gt;92.77&lt;/mn&gt; &lt;mo&gt;±&lt;/mo&gt; &lt;mn&gt;10.74&lt;/mn&gt;&lt;/mrow&gt; &lt;/math&gt; compared with &lt;math&gt;&lt;mrow&gt;&lt;mn&gt;86.35&lt;/mn&gt; &lt;mo&gt;±&lt;/mo&gt; &lt;mn&gt;3.97&lt;/mn&gt;&lt;/mrow&gt; &lt;/math&gt; , and &lt;math&gt;&lt;mrow&gt;&lt;mn&gt;84.52&lt;/mn&gt; &lt;mo&gt;±&lt;/mo&gt; &lt;mn&gt;11.82&lt;/mn&gt;&lt;/mrow&gt; &lt;/math&gt; with U-Net for kidney, and tumor, respectively) and contrast-to-noise ratio ( &lt;math&gt;&lt;mrow&gt;&lt;mn&gt;11.82&lt;/mn&gt; &lt;mo&gt;±&lt;/mo&gt; &lt;mn&gt;4.42&lt;/mn&gt;&lt;/mrow&gt; &lt;/math&gt; , and &lt;math&gt;&lt;mrow&gt;&lt;mn&gt;9.9&lt;/mn&gt; &lt;mo&gt;±&lt;/mo&gt; &lt;mn&gt;4.41&lt;/mn&gt;&lt;/mrow&gt; &lt;/math&gt; compared with &lt;math&gt;&lt;mrow&gt;&lt;mn&gt;7.59&lt;/mn&gt; &lt;mo&gt;±&lt;/mo&gt; &lt;mn&gt;0.82&lt;/mn&gt;&lt;/mrow&gt; &lt;/math&gt; , and &lt;math&gt;&lt;mrow&gt;&lt;mn&gt;6.82&lt;/mn&gt; &lt;mo&gt;±&lt;/mo&gt; &lt;mn&gt;2.12&lt;/mn&gt;&lt;/mrow&gt; &lt;/math&gt; with U-Net for kidney, and tumor respectively). The use of cGAN with single-pulse rapid imaging has the potential to prevent photobleaching ( &lt;math&gt;&lt;mrow&gt;&lt;mn&gt;9.51&lt;/mn&gt; &lt;mo&gt;±&lt;/mo&gt; &lt;mn&gt;3.69&lt;/mn&gt; &lt;mo&gt;%&lt;/mo&gt;&lt;/mrow&gt; &lt;/math&gt; with cGAN, and &lt;math&gt;&lt;mrow&gt;&lt;mn&gt;35.14&lt;/mn&gt; &lt;mo&gt;±&lt;/mo&gt; &lt;mn&gt;5.38&lt;/mn&gt; &lt;mo&gt;%&lt;/mo&gt;&lt;/mrow&gt; &lt;/math&gt; with long-time laser exposure by averaging 30 pulses), enabling accurate, quantitative imaging suitable for real-time implementation, and improved clinical decision support.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Conclusions: &lt;/strong&gt;We demonstrate the potential of a platform-flexible generative deep learning-based approach to mitigate the effects of photobleaching in PA imaging by enhancing signal-to-noise ratio from single pulse-illuminated data, the","PeriodicalId":15264,"journal":{"name":"Journal of Biomedical Optics","volume":"30 Suppl 3","pages":"S34102"},"PeriodicalIF":3.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12118878/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144179917","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Improved temporal speckle contrast model for slow and fast dynamic: effect of temporal correlation among neighboring pixels.","authors":"Julio Cesar Juarez-Ramirez, Beatriz Coyotl-Ocelotl, David Ivan Loaiza-Toscuento, Teresita Spezzia-Mazzocco, Bernard Choi, Ruben Ramos-Garcia, Juan Pablo Padilla-Martinez, Julio Cesar Ramirez-San-Juan","doi":"10.1117/1.JBO.30.7.076007","DOIUrl":"10.1117/1.JBO.30.7.076007","url":null,"abstract":"<p><strong>Significance: </strong>Speckle contrast analysis, whether spatial or temporal, is a valuable optical technique extensively utilized in medical and engineering domains owing to its simplicity, affordability, and noninvasive nature. It relies on statistical analysis of the dynamic speckle pattern produced by the sample under examination, offering insights into the sample's dynamics. However, challenges persist in precisely measuring temporal speckle contrast, particularly for slow dynamic samples. Existing mathematical models fail to accurately reflect the experimental data, which could result in misinterpretation of the analyzed results.</p><p><strong>Aim: </strong>To overcome these constraints, we present a mathematical model that incorporates the correlation between adjacent pixels. We specifically concentrate on temporal correlation, i.e., the relationship between neighboring frames, to compute the temporal speckle contrast.</p><p><strong>Approach: </strong>We theoretically replicate the statistical analysis typically conducted to compute temporal speckle contrast in a series of consecutive raw speckle images. Unlike previous models, our calculations account for the potential correlation between neighboring pixels across successive frames. To validate this model, we apply it to the analysis of the dynamics of <i>Escherichia coli</i> ATCC 25922 colonies.</p><p><strong>Results: </strong>By considering the probable temporal correlation between neighboring pixels, the proposed model notably improves the precision of temporal speckle contrast measurements, particularly for slow dynamic samples. Analytical expressions for the contrast are derived, incorporating both Gaussian and Lorentzian correlation functions, which exhibit excellent agreement with experimental findings conducted on <i>E. coli</i> colonies. Conversely, for fast dynamic samples where neighboring pixels lack correlation, our model aligns with the outcomes of the previously reported models.</p><p><strong>Conclusions: </strong>The proposed model is well-suited for computing temporal contrast in both slow and fast dynamics, rendering it applicable to a wide range of biological and industrial systems.</p>","PeriodicalId":15264,"journal":{"name":"Journal of Biomedical Optics","volume":"30 7","pages":"076007"},"PeriodicalIF":3.0,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12271750/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144674837","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"DOT-AE-GAN: a hybrid autoencoder-GAN model for enhanced ultrasound-guided diffuse optical tomography reconstruction.","authors":"Md Iqbal Hossain, Minghao Xue, Lukai Wang, Quing Zhu","doi":"10.1117/1.JBO.30.7.076003","DOIUrl":"10.1117/1.JBO.30.7.076003","url":null,"abstract":"<p><strong>Significance: </strong>Diffuse optical tomography (DOT) is a noninvasive functional imaging technique; however, the reconstruction of high-quality images from DOT data is a challenging task because of the ill-posed nature of the inverse problem. We introduce a hybrid machine learning model that combines the strengths of autoencoders (AEs) and generative adversarial networks (GANs) for robust DOT reconstruction.</p><p><strong>Aim: </strong>We leveraged a hybrid machine learning model for robust ultrasound-guided DOT reconstruction.</p><p><strong>Approach: </strong>A hybrid model, DOT-AE-GAN, that combines the strengths of AEs and GANs to enhance the robustness of DOT reconstruction is introduced. The proposed model utilizes an AE to efficiently encode the DOT measurement to reconstruction and decode back to measurement, modeling the inverse and forward process of reconstruction. In parallel, a GAN framework is incorporated to enhance the robustness of the reconstruction for irregularly shaped lesions, utilizing adversarial training.</p><p><strong>Results: </strong>The DOT-AE-GAN model is first trained and validated using simulations, demonstrating reconstruction accuracy in absorption coefficients and lateral dimensions of the targets. The DOT-AE-GAN is then fine-tuned with phantom data and compared with the AE model, showing the improvement over the AE model in the reconstructed target lateral dimension while keeping similar accuracy in absorption coefficient. The DOT-AE-GAN is validated with patient data, revealing that the DOT-AE-GAN-reconstructed breast lesion lateral dimensions follow size measurements of co-registered ultrasound significantly better than the optimization-based reconstruction algorithm and AE model with improved absorption contrast between malignant and benign lesions.</p><p><strong>Conclusions: </strong>Our results demonstrate that the DOT-AE-GAN model has great potential in ultrasound-guided DOT reconstruction.</p>","PeriodicalId":15264,"journal":{"name":"Journal of Biomedical Optics","volume":"30 7","pages":"076003"},"PeriodicalIF":3.0,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12225985/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144575560","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Flexible catheter optical coherence tomography of the porcine middle ear via the Eustachian tube using a 3D-printed reflective objective.","authors":"Clayton B Walker, Kevin Beckford, Zihan Yang, Jinyun Liu, Wihan Kim, Tomasz S Tkaczyk, Brian E Applegate","doi":"10.1117/1.JBO.30.7.076002","DOIUrl":"10.1117/1.JBO.30.7.076002","url":null,"abstract":"<p><strong>Significance: </strong>Cholesteatomas, benign tumors that grow in the middle ear, can lead to conductive hearing loss. If not completely removed during surgery, these tumors may regrow. Current imaging technologies struggle to detect residual tumors noninvasively due to limitations in contrast and resolution, often necessitating additional surgery for inspection. To address this, we developed a catheter endoscope capable of being inserted through the Eustachian tube, allowing detailed examination of the middle ear without surgery. Using two-photon polymerization (2PP) technology, we fabricated miniature, side-viewing reflective endoscope objectives. This approach enabled the rapid production of single-element objectives with highly repeatable optical properties, easily adaptable to specific imaging needs.</p><p><strong>Aim: </strong>We aim to design, fabricate, and demonstrate a catheter endoscope for optical coherence tomography (OCT) endoscopy of the middle ear via the Eustachian tube.</p><p><strong>Approach: </strong>Side-viewing, reflective lenses were designed in OpticStudio and 3D printed using 2PP followed by sputter coating with gold. Standard metrology techniques were used to verify and optimize the objective's shape. The optical performance of the catheter endoscopes was measured with a beam profiler. Finally, OCT imaging of the middle ear of a pig via the Eustachian tube was completed using the fully assembled catheter endoscope.</p><p><strong>Results: </strong>Metrology showed the printed lenses conformed closely to the design. The catheter endoscope's FWHM spot size had a mean ± standard deviation of <math><mrow><mn>25.3</mn> <mo>±</mo> <mn>1.8</mn> <mtext>  </mtext> <mi>μ</mi> <mi>m</mi></mrow> </math> with a measured working distance of <math><mrow><mn>1.960</mn> <mo>±</mo> <mn>0.057</mn> <mtext>  </mtext> <mi>mm</mi></mrow> </math> . Volumetric OCT images of the middle ear, inner ear, and Eustachian tube were captured in a postmortem pig head using the catheter endoscope.</p><p><strong>Conclusions: </strong>The 2PP approach is fast and highly repeatable for miniature reflective objective fabrication. OCT catheter endoscopy via the Eustachian tube enabled imaging of the middle ear, Eustachian tube, and surprisingly part of the inner ear.</p>","PeriodicalId":15264,"journal":{"name":"Journal of Biomedical Optics","volume":"30 7","pages":"076002"},"PeriodicalIF":3.0,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12223792/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144575561","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Advancing infantile hemangioma diagnosis by integrating temperature, color, and texture.","authors":"José Antonio Pérez-Carrasco, Carmen Serrano, Juan Antonio Leñero-Bardallo, José Bernabeu-Wittel, Begoña Acha","doi":"10.1117/1.JBO.30.7.075001","DOIUrl":"10.1117/1.JBO.30.7.075001","url":null,"abstract":"<p><strong>Significance: </strong>Infantile hemangiomas are one of the most prevalent benign tumors in childhood. Typically, diagnosis relies on visual assessment of area, texture, and color. A few studies have focused on various color attributes in superficial and mixed Infantile hemangioma types, neglecting the deep category. Limited research has explored temperature in the location of hemangioma lesions.</p><p><strong>Aim: </strong>We seek, for the first time, to quickly identify and classify infantile hemangioma lesions using a portable, programmable handheld device. The system aims to (1) replicate a physician's assessment of infantile hemangioma and (2) deliver an easy way to understand automatic diagnosis.</p><p><strong>Approach: </strong>The custom-built device comprises an infrared sensor and a visible light spectrum sensor to assess color and depth through computations of different color and texture features. Over a 3-year period, 53 patients were monitored, and 83 hemangioma images were captured.</p><p><strong>Results: </strong>The device accurately localized all lesions in real time and classified hemangioma lesions into three primary types using selected color and texture features. Evaluation metrics showed an average sensitivity of 0.8948 and specificity of 0.7313 for an accuracy of 0.7572 and an average sensitivity of 0.7803 and specificity of 0.8720 for an <math><mrow><mi>F</mi></mrow> </math> -score of 0.7826 in the three-class classification.</p><p><strong>Conclusions: </strong>The two-sensor device accurately identifies and categorizes infantile hemangioma lesions, providing a clear automated diagnosis based on computerized features.</p>","PeriodicalId":15264,"journal":{"name":"Journal of Biomedical Optics","volume":"30 7","pages":"075001"},"PeriodicalIF":3.0,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12270544/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144659342","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Anthropomorphic tissue-mimicking phantoms for oximetry validation in multispectral optical imaging.","authors":"Kris K Dreher, Janek Gröhl, Friso Grace, Leonardo Ayala, Jan-Hinrich Nölke, Christoph J Bender, Melissa J Watt, Katie-Lou White, Ran Tao, Wibke Johnen, Minu D Tizabi, Alexander Seitel, Lena Maier-Hein, Sarah E Bohndiek","doi":"10.1117/1.JBO.30.7.076006","DOIUrl":"10.1117/1.JBO.30.7.076006","url":null,"abstract":"<p><strong>Significance: </strong>Optical imaging of blood oxygenation ( <math> <mrow><msub><mi>sO</mi> <mn>2</mn></msub> </mrow> </math> ) can be achieved based on the differential absorption spectra of oxy- and deoxyhemoglobin. A key challenge in realizing clinical validation of the <math> <mrow><msub><mi>sO</mi> <mn>2</mn></msub> </mrow> </math> biomarkers is the absence of reliable <math> <mrow><msub><mi>sO</mi> <mn>2</mn></msub> </mrow> </math> reference standards, including test objects.</p><p><strong>Aim: </strong>To enable quantitative testing of multispectral imaging methods for assessment of <math> <mrow><msub><mi>sO</mi> <mn>2</mn></msub> </mrow> </math> by introducing anthropomorphic phantoms with appropriate tissue-mimicking optical properties.</p><p><strong>Approach: </strong>We used the stable copolymer-in-oil base material to create physical anthropomorphic structures and optimized dyes to mimic the optical absorption of blood across a wide spectral range. Using 3D-printed phantom molds generated from a magnetic resonance image of a human forearm, we molded the material into an anthropomorphic shape. Using both reflectance hyperspectral imaging (HSI) and photoacoustic tomography (PAT), we acquired images of the forearm phantoms and evaluated the performance of linear spectral unmixing (LSU).</p><p><strong>Results: </strong>Based on 10 fabricated forearm phantoms with vessel-like structures featuring five distinct <math> <mrow><msub><mi>sO</mi> <mn>2</mn></msub> </mrow> </math> levels (between 0 and 100%), we showed that the measured absorption spectra of the material correlated well with HSI and PAT data with a Pearson correlation coefficient consistently above 0.8. Further, the application of LSU enabled a quantification of the mean absolute error in <math> <mrow><msub><mi>sO</mi> <mn>2</mn></msub> </mrow> </math> assessment with HSI and PAT.</p><p><strong>Conclusions: </strong>Our anthropomorphic tissue-mimicking phantoms hold potential to provide a robust tool for developing, standardising, and validating optical imaging of <math> <mrow><msub><mi>sO</mi> <mn>2</mn></msub> </mrow> </math> .</p>","PeriodicalId":15264,"journal":{"name":"Journal of Biomedical Optics","volume":"30 7","pages":"076006"},"PeriodicalIF":3.0,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12267859/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144659343","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Depth-dependent fluence compensation without <i>a priori</i> knowledge of tissue composition for quantitative ultrasound-guided photoacoustic imaging.","authors":"David Qin, Xinyue Huang, Timothy Sowers, Donald VanderLaan, Stanislav Emelianov","doi":"10.1117/1.JBO.30.7.076005","DOIUrl":"10.1117/1.JBO.30.7.076005","url":null,"abstract":"<p><strong>Significance: </strong>Compensation for depth-dependent fluence without <i>a priori</i> knowledge of tissue composition is a crucial unmet need for quantitative photoacoustic imaging.</p><p><strong>Aim: </strong>We developed a method for estimating the effective optical attenuation coefficient of bulk tissue with composition and optical properties that are not known in advance, through combined ultrasound/photoacoustic imaging during mechanical displacement of tissue.</p><p><strong>Approach: </strong>Ultrasound/photoacoustic imaging was performed on a target embedded in biological media while applying tissue displacement to change the optical path. After compensation for geometry-dependent scattering of light from light source apertures, the change of photoacoustic amplitude against optical path length was used to estimate the effective optical attenuation coefficient.</p><p><strong>Results: </strong>Using the developed approach, the estimation of the effective optical attenuation coefficient of tissue-mimicking (milk/water) phantoms and <i>ex vivo</i> porcine muscle and chicken breast was accurate compared with ground-truth literature values.</p><p><strong>Conclusions: </strong>Regardless of the varying geometries used for light delivery in photoacoustic imaging, it is feasible to perform ultrasound-guided photoacoustic imaging with simultaneous mechanical displacement of tissue to determine the effective optical attenuation coefficient of bulk tissue along the light path to the target.</p>","PeriodicalId":15264,"journal":{"name":"Journal of Biomedical Optics","volume":"30 7","pages":"076005"},"PeriodicalIF":3.0,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12255355/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144626491","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of layered tissue scattering properties: a time-domain spatially resolved spectroscopy approach.","authors":"Elisabetta Avanzi, Laura Di Sieno, Alberto Dalla Mora, Lorenzo Spinelli, Alessandro Torricelli","doi":"10.1117/1.JBO.30.7.075002","DOIUrl":"10.1117/1.JBO.30.7.075002","url":null,"abstract":"<p><strong>Significance: </strong>The spatially resolved spectroscopy (SRS) approach is widely used in continuous wave near-infrared spectroscopy to estimate tissue oxygen saturation in the skeletal muscle and cerebral cortex. The extension of the SRS approach to the time domain (TD) has never been proposed. We hypothesize that the time-domain spatially resolved spectroscopy (TD SRS) approach, relying on simple models and linear fit, avoiding nonlinear model-based analysis approaches, could be able to assess the homogeneity of the scattering of the explored tissue.</p><p><strong>Aim: </strong>We aim to explore the potential of the TD SRS approach for estimating <math> <mrow> <msubsup><mrow><mi>μ</mi></mrow> <mrow><mi>s</mi></mrow> <mrow><mo>'</mo></mrow> </msubsup> </mrow> </math> from the spatial derivative of the measured signal in a homogeneous and in a two-layer medium and by considering also the effect of the instrument response function (IRF).</p><p><strong>Approach: </strong>A theoretical expression for <math> <mrow> <msubsup><mrow><mi>μ</mi></mrow> <mrow><mi>s</mi></mrow> <mrow><mo>'</mo></mrow> </msubsup> </mrow> </math> depending on the spatial derivative of the attenuation is derived. Then, numerical simulations are conducted using solutions of the radiative transfer equation under the diffusion approximation. We consider a reflectance geometry with source-detector distance in the range 1 to 5 cm in 0.5 cm step, either in a homogenous semi-infinite or two-layer diffusive medium. Convolution with a real IRF is also carried out to mimic experimental scenarios.</p><p><strong>Results: </strong>In a homogeneous medium, the TD SRS approach is able to retrieve <math> <mrow> <msubsup><mrow><mi>μ</mi></mrow> <mrow><mi>s</mi></mrow> <mrow><mo>'</mo></mrow> </msubsup> </mrow> </math> over a large range of values, being minimally affected by the IRF. In a two-layer medium, the TD SRS approach can only provide information on the changes of <math> <mrow> <msubsup><mrow><mi>μ</mi></mrow> <mrow><mi>s</mi></mrow> <mrow><mo>'</mo></mrow> </msubsup> </mrow> </math> with depth but fails to provide a robust estimate of the absolute value of <math> <mrow> <msubsup><mrow><mi>μ</mi></mrow> <mrow><mi>s</mi></mrow> <mrow><mo>'</mo></mrow> </msubsup> </mrow> </math> in either of the two layers. Moreover, the IRF can greatly affect the results in the case of the two-layer medium.</p><p><strong>Conclusions: </strong>The TD SRS approach can be a simple way to estimate spatial changes of <math> <mrow> <msubsup><mrow><mi>μ</mi></mrow> <mrow><mi>s</mi></mrow> <mrow><mo>'</mo></mrow> </msubsup> </mrow> </math> but not the absolute value of <math> <mrow> <msubsup><mrow><mi>μ</mi></mrow> <mrow><mi>s</mi></mrow> <mrow><mo>'</mo></mrow> </msubsup> </mrow> </math> . Care should be taken to use a TD system with proper IRF.</p>","PeriodicalId":15264,"journal":{"name":"Journal of Biomedical Optics","volume":"30 7","pages":"075002"},"PeriodicalIF":3.0,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12279310/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144682654","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}