PA Images Research Articles

Vascular regional analysis unveils differential responses to anti-angiogenic therapy in pancreatic xenografts through macroscopic photoacoustic imaging.

Pancreatic cancer (PC) is a highly lethal malignancy and the third leading cause of cancer deaths in the U.S. Despite major innovations in imaging technologies, there are limited surrogate radiographic indicators to aid in therapy planning and monitoring. Amongst the various imaging techniques Ultrasound-guided photoacoustic imaging (US-PAI) is a promising modality based on endogenous blood (hemoglobin) and blood oxygen saturation (StO 2 ) contrast to monitor response to anti-angiogenic therapies. Adaptation of US-PAI to the clinical realm requires macroscopic configurations for adequate depth visualization, illuminating the need for surrogate radiographic markers, including the tumoral microvessel density (MVD). In this work, subcutaneous xenografts with PC cell lines AsPC-1 and MIA-PaCa-2 were used to investigate the effects of receptor tyrosine kinase inhibitor (sunitinib) treatment on MVD and StO 2 . Through histological correlation, we have shown that regions of high and low vascular density (HVD and LVD) can be identified through frequency domain filtering of macroscopic PA images which could not be garnered from purely global analysis. We utilized vascular regional analysis (VRA) of treatment-induced StO 2 and total hemoglobin (HbT) changes. VRA as a tool to monitor treatment response allowed us to identify potential timepoints of vascular remodeling, highlighting its ability to provide insights into the TME not only for sunitinib treatment but also other anti-angiogenic therapies.

Vector-flow imaging of slowly moving ex vivo blood with photoacoustics and pulse-echo ultrasound

We present a technique called photoacoustic vector-flow (PAVF) to quantify the speed and direction of flowing optical absorbers at each pixel from acoustic-resolution PA images. By varying the receiving angle at each pixel in post-processing, we obtain multiple estimates of the phase difference between consecutive frames. These are used to solve the overdetermined photoacoustic Doppler equation with a least-squares approach to estimate a velocity vector at each pixel. This technique is tested in bench-top experiments and compared to simultaneous pulse-echo ultrasound vector-flow (USVF) on whole rat blood at speeds on the order of 1 mm/s. Unlike USVF, PAVF can detect flow without stationary clutter filtering in this experiment, although the velocity estimates are highly underestimated. When applying spatio-temporal singular value decomposition clutter filtering, the flow speed can be accurately estimated with an error of 16.8% for USVF and −8.9% for PAVF for an average flow speed of 2.5 mm/s.

The effect of tumor vascular remodeling and immune microenvironment activation induced by radiotherapy: quantitative evaluation with magnetic resonance/photoacoustic dual-modality imaging.

Tumor radiotherapy combined with immunotherapy for solid tumors has been proposed, but tumor vascular structure abnormalities and immune microenvironment often affect the therapeutic effect of tumor, and multimodal imaging technology can provide more accurate and comprehensive information in tumor research. The purpose of this study was to evaluate the dynamic monitoring of tumor blood vessels and microenvironment induced by radiotherapy by magnetic resonance/photoacoustic (MR/PA) imaging, and to explore its application value in radiotherapy combined with immunotherapy. The tumor-bearing mice were randomly allocated into six groups, which received different doses of radiation therapy (2 Gy ×14 or 8 Gy ×3) and anti-programmed death ligand-1 (PD-L1) antibody for two consecutive weeks. MR/PA imaging was used to noninvasively evaluate the response of tumor to different doses of radiotherapy, combined with histopathological techniques to observe the tumor vessels and microenvironment. The inhibitory effect of high-dose radiotherapy on tumors was significantly greater than that of low-dose radiotherapy, with the MR images revealing that the signal intensity decreased significantly (P<0.05). Compared with those in the other groups, the tumor vascular density decreased significantly (P<0.01), and the vascular maturity index increased significantly in the low-dose group (P<0.05). The PA images showed that the deoxyhemoglobin and total hemoglobin levels decreased and the SO2 level increased after radiation treatment (P<0.05). In addition, the high-dose group had an increased number of tumor-infiltrating lymphocytes (CD4+ T and CD8+ T cells) (P<0.01, P<0.05) and natural killer cells (P<0.001) and increased PD-L1 expression in the tumors (P<0.05). The combination of radiotherapy and immunotherapy increased the survival rate of the mice (P<0.05), and a regimen of an 8 Gy dose of radiation combined with immunotherapy inhibited tumor growth and increased the survival rate of the mice to a greater degree than the 2 Gy radiation dose with immunotherapy combination (P=0.002). Differential fractionation radiotherapy doses exert biological effects on tumor vascular and the immune microenvironment, and MR/PA can be used to evaluate tumor vascular remodeling after radiotherapy, which has certain value for the clinical applications of radiotherapy combined with immunotherapy.

Stimuli‐Responsive Organic Near‐Infrared Photoacoustic Probes

AbstractPhotoacoustic (PA) imaging is an emerging biomedical imaging technique with the features of non‐invasiveness and non‐ionization. It takes advantage of the photothermal effect of PA probes to convert absorbed photon energy into heat and subsequent transient thermoelastic tissue expansion for ultrasonic waves for PA images. Thus, PA imaging exhibits the combined superiority of high‐contrast optical imaging and deep tissue penetration of acoustic imaging, which furnishes high‐resolution and high‐contrast tissue images. Stimuli‐responsive organic PA agents in the near‐infrared (NIR) biological window have attracted increasing attention because of their low biological toxicity and response characteristics. This review focuses on the recent research progress of stimuli‐responsive organic NIR probes for PA imaging, including the temperature response, pH response, redox response, metal ion response, and enzyme response. And the stimuli‐responsive mechanisms are highlighted in detail. Moreover, their perspectives and challenges are discussed. It will be of great help for the further development of organic NIR PA probes with stimuli‐response.

Adaptive denoising of photoacoustic signal and image based on modified Kalman filter.

As a burgeoning medical imaging method based on hybrid fusion of light and ultrasound, photoacoustic imaging (PAI) has demonstrated high potential in various biomedical applications, especially in revealing the functional and molecular information to improve diagnostic accuracy. However, stemming from weak amplitude and unavoidable random noise, caused by limited laser power and severe attenuation in deep tissue imaging, PA signals are usually of low signal-to-noise ratio, and reconstructed PA images are of low quality. Despite that conventional Kalman filter (KF) can remove Gaussian noise in time domain, it lacks adaptability in real-time estimation due to its fixed model. Moreover, KF-based denoising algorithm has not been applied in PAI before. In this paper, we propose an adaptive modified KF (MKF) targeted at PAI denoising by tuning system noise matrix Q and measurement noise matrix R in the conventional KF model. Additionally, in order to compensate the signal skewing caused by MKF, we cascade the backward part of Rauch-Tung-Striebel smoother, which utilizes the newly determined Q. Finally, as a supplement, we add a commonly used differential filter to remove in-band reflection artifacts. Experimental results using phantom and ex vivo colorectal tissue are provided to prove validity of the algorithm.

Acoustic-resolution-based spectroscopic photoacoustic endoscopy towards molecular imaging in deep tissues.

Due to many technical difficulties, the study of molecular photoacoustic endoscopic (PAE) imaging in deep tissues is limited. In this work, we have set up a multimodal acoustic-resolution-based PAE (AR-PAE) system to image the rabbit rectum and preliminarily explored the potential of molecular PAE for deep-seated targets in proof-of-concept. We developed an improved back-projection (IBP) algorithm for focused detection over the centimeter-scale imaging depth. We also developed a deep-learning-based algorithm to remove the electrical noise from the step motor to prevent data averaging for reduced scanning time. We injected a dose of indocyanine green (ICG) near the rabbit rectum and compared 2D and 3D photoacoustic/ultrasound (PA/US) images at different wavelengths. We proposed incorporating a small camera to guide the slow PA/US endoscopic scan. Results show that this system has achieved a lateral resolution of about 0.77/0.65 mm for PA/US images with a signal-to-noise ratio (SNR) of 25/38 dB at an imaging depth of 1.4 cm. We found that the rectum wall and the ICG can be well distinguished spectroscopically. Results also show that the PA images at 532 nm have higher signal intensity and reflection artifacts from pelvic tendons and bones than those at longer wavelengths such as 800 nm. The proposed methods and the intuitive findings in this work may guide and promote the development of high-penetration molecular PAE.

Photoacoustic imaging provides an in vivo assessment of the preeclamptic placenta remodeling and function in response to therapy

IntroductionThere is a lack of effective therapeutic interventions for preeclampsia. A central factor in the etiology of the disease is the development of placental hypoxia due to abnormal vascular remodeling. However, methods to assess the impact of potential therapies on placental growth and remodeling are currently lacking. Here, we develop and validate ultrasound-guided photoacoustic imaging methods to monitor the placental response to therapeutic intervention. Establishing non-invasive tools to image placental function opens up previously unachievable understandings of placental therapeutic response. MethodsStudies were performed in the reduced uterine perfusion pressure (RUPP) rat model of preeclampsia. Preclinical research has identified tempol, a superoxide dismutase mimetic, and the phosphodiesterase inhibitor sildenafil as potential therapeutics for preeclampsia, as both improve in vivo maternal outcomes. PA images of the placental environment were acquired in RUPP rats receiving tempol (n = 8) or sildenafil (n = 8) to assess the longitudinal effects of treatment on placental oxygenation and vascular remodeling. Imaging measurements were validated with ex vivo histological analysis. ResultsSpectral photoacoustic imaging non-invasively measured placental hypoxia and impaired vascular growth two days after the RUPP procedure was implemented. Sildenafil significantly improved (p < 0.05) placental oxygenation and promoted vascular remodeling in RUPP animals, while RUPP animals treated with tempol had a diminished placental therapeutic response. DiscussionWe demonstrate that photoacoustic imaging provides in vivo measures of placental oxygenation and vascular remodeling, a previously unobtainable assessment of preeclamptic therapeutic response. These imaging tools have tremendous potential to accelerate the search for effective therapies for preeclampsia.

CBCT Patterns of Bone Loss and Clinical Predictors for the Diagnosis of Cracked Teeth and Teeth with Vertical Root Fracture

IntroductionThis study aimed to identify clinical and radiographic characteristics of teeth with longitudinal fractures to assist in the diagnosis and differentiation between cracked teeth and teeth with vertical root fracture (VRF). MethodsNinety-five patients (95 teeth) diagnosed with a longitudinal fracture (only cracked teeth or VRF) through clinical visualization of the fracture line were included in this study. Clinical and radiographic data were collected from the patients' records to identify the characteristics associated with each condition. Fifty-four patients (54 teeth) had full radiographic (periapical [PA] radiography and a cone-beam computed tomographic [CBCT] scan) and clinical findings (probing depths and clinical images of the fracture line). PA and CBCT images were evaluated by 2 independent examiners to identify the different patterns of bone loss associated with these teeth (no defect, an angular defect, a J-shaped defect, or a combined defect). Cohen kappa analysis was used to compare the results between the 2 examiners and between the findings of the PA and CBCT images. Pearson chi-square analysis, the Fisher exact test, and adjusted Bonferroni post hoc testing were used to establish an association between the type and extension of the longitudinal fracture with the probing depth, the CBCT pattern of bony defects, and the presence/absence of the buccal plate and also to compare the clinical and radiographic characteristics of cracked teeth and teeth with VRF (P < .05). ResultsCBCT images had 4.4 times the odds of detecting bony defects suggestive of longitudinal fractures compared with PA radiographs. Teeth with VRF were more associated with indirect restorations, deep probing (>6 mm), absence of the cortical plate, and a J-shaped defect on the CBCT image (P < .05). On the other hand, cracked teeth were associated with direct restorations, shallow probing (<6 mm), an intact cortical plate, and the presence of an angular defect on the CBCT image (P < .001). There was a significant correlation between a radicular extension of the fracture line and deep probing as well as J-shaped defects (P < .05). ConclusionsPatterns of bone loss on CBCT imaging can likely differentiate between cracked teeth and teeth with VRF. The presence of an angular defect may suggest the presence of a crack in the tooth before intervention. J-shaped defects, deep probing (>6 mm), and loss of the cortical plate are likely suggestive of VRF.

Programmable Acoustic Delay-Line Enabled Low-Cost Photoacoustic Tomography System.

Photoacoustic tomography (PAT) is an emerging technology for biomedical imaging that combines the superiorities of high optical contrast and acoustic penetration. In the PAT system, more PA signals are preferred to be detected from full field of view to reconstruct the PA images with higher fidelity. However, the requirement for more PA signals' detection leads to more time consumption for single-channel scanning-based PAT system or higher cost of data acquisition (DAQ) module for an array-based PAT system. To address this issue, we proposed a programmable acoustic delay-line (PADL) module to reduce DAQ cost and accelerate imaging speed for PAT system. The module is based on bidirectional conversion between acoustic signals and electrical signals, including ultrasound transmission in between to provide sufficient time delay. The acoustic delay-line module achieves tens or hundreds of microseconds' delay for each channel and is controlled by a programmable control unit. In this work, it achieves to merge four inputs of PA signals into one output signal, which can be recovered into original four PA signals in the digital domain after DAQ. The imaging experiments of pencil leads embedded in agar phantom are conducted by the PAT system equipped with the proposed PADL module, which demonstrated its feasibility to reduce the cost of the PAT system. An in vivo study of human finger PAT imaging with delay-line module verified its feasibility for biomedical imaging applications.

A General Approach to Design Dual Ratiometric Fluorescent and Photoacoustic Probes for Quantitatively Visualizing Tumor Hypoxia Levels In Vivo.

Herein, we describe an energy balance strategy between fluorescence and photoacoustic effects by sulfur substitution to transform existing hemicyanine dyes (Cy) into optimized NIRF/PA dual ratiometric scaffolds. Based on this optimized scaffold, we reported the first dual-ratio response of nitroreductase probe AS-Cy-NO2 , which allows quantitative visualization of tumor hypoxia in vivo. AS-Cy-NO2 , composed of a new NIRF/PA scaffold thioxanthene-hemicyanine (AS-Cy-1) and a 4-nitrobenzene moiety, showed a 10-fold ratiometric NIRF enhancement (I773 /I733 ) and 2.4-fold ratiometric PA enhancement (PA730 /PA670 ) upon activation by a biomarker (nitroreductase, NTR) associated with tumor hypoxia. Moreover, the dual ratiometric NIRF/PA imaging accurately quantified the hypoxia extent with high sensitivity and high imaging depth in xenograft breast cancer models. More importantly, the 3D maximal intensity projection (MIP) PA images of the probe can precisely differentiate the highly heterogeneous oxygen distribution in solid tumor. Thus, this study provides a promising NIRF/PA scaffold that may be generalized for the dual ratiometric imaging of other disease-relevant biomarkers.

A General Approach to Design Dual Ratiometric Fluorescent and Photoacoustic Probes for Quantitatively Visualizing Tumor Hypoxia Levels In Vivo

AbstractHerein, we describe an energy balance strategy between fluorescence and photoacoustic effects by sulfur substitution to transform existing hemicyanine dyes (Cy) into optimized NIRF/PA dual ratiometric scaffolds. Based on this optimized scaffold, we reported the first dual‐ratio response of nitroreductase probe AS‐Cy‐NO2, which allows quantitative visualization of tumor hypoxia in vivo. AS‐Cy‐NO2, composed of a new NIRF/PA scaffold thioxanthene‐hemicyanine (AS‐Cy‐1) and a 4‐nitrobenzene moiety, showed a 10‐fold ratiometric NIRF enhancement (I773/I733) and 2.4‐fold ratiometric PA enhancement (PA730/PA670) upon activation by a biomarker (nitroreductase, NTR) associated with tumor hypoxia. Moreover, the dual ratiometric NIRF/PA imaging accurately quantified the hypoxia extent with high sensitivity and high imaging depth in xenograft breast cancer models. More importantly, the 3D maximal intensity projection (MIP) PA images of the probe can precisely differentiate the highly heterogeneous oxygen distribution in solid tumor. Thus, this study provides a promising NIRF/PA scaffold that may be generalized for the dual ratiometric imaging of other disease‐relevant biomarkers.

Design of Continuously-Adjustable Light-Scanning Handheld Probe for Photoacoustic Imaging

To form various images at multiple locations for achieving bright- and dark-illumination fields transformation and registration-free image fusion, we proposed a continuously-adjustable light-scanning handheld probe with overall size of 60 × 45 × 80 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> for photoacoustic imaging (PAI). It has a significant advantage for image acquisition under different illumination schemes using motor driving. Specifically, a light adjustment unit was designed to produce light spots, which is more compatible with ultrasonic transducer detection region. Afterwards, multiple PA images revealing diverse features with different optical illumination regions were acquired. Consequently, the fused image was obtained with higher SNR and fidelity than respective PA image. Furthermore, both phantom and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ex-vivo</i> experiments were conducted to evaluate imaging performance of the developed probe. Experimental results show that SNR of the fused PA image improves by 36.06% in agar-milk phantom and 44.69% in <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ex-vivo</i> chicken breast, respectively. Therefore, the proposed PAI handheld probe can achieve our goals well; the registration-free image fusion achieved by adaptive scanning strategy can perform better and demonstrate comprehensive features of the same imaging target.

Modeling combined ultrasound and photoacoustic imaging: Simulations aiding device development and artificial intelligence

Combined ultrasound and photoacoustic (USPA) imaging has attracted several pre-clinical and clinical applications due to its ability to simultaneously display structural, functional, and molecular information of deep biological tissue in real time. However, the depth and wavelength dependent optical attenuation and the unknown optical and acoustic heterogeneities limit the USPA imaging performance in deep tissue regions. Novel instrumentation, image reconstruction, and artificial intelligence (AI) methods are currently being investigated to overcome these limitations and improve the USPA image quality. Effective implementation of these approaches requires a reliable USPA simulation tool capable of generating US based anatomical and PA based molecular contrasts of deep biological tissue. Here, we developed a hybrid USPA simulation platform by integrating finite element models of light (NIRFast) and ultrasound (k-Wave) propagations for co-simulation of B-mode US and PA images. The platform allows optimization of different design parameters for USPA devices, such as the aperture size and frequency of both light and ultrasound detector arrays. For designing tissue-realistic digital phantoms, a dictionary-based function has been added to k-Wave to generate various levels of ultrasound speckle contrast. The feasibility of modeling US imaging combined with optical fluence dependent multispectral PA imaging is demonstrated using homogeneous as well as heterogeneous tissue phantoms mimicking human organs (e.g., prostate and finger). In addition, we also demonstrate the potential of the simulation platform to generate large scale application-specific training and test datasets for AI enhanced USPA imaging. The complete USPA simulation codes together with the supplementary user guides have been posted to an open-source repository (https://github.com/KothapalliLabPSU/US-PA_simulation_codes).

Enhancement of in vivo cardiac photoacoustic signal specificity using spatiotemporal singular value decomposition.

.Significance: Photoacoustic imaging (PAI) can be used to infer molecular information about myocardial health non-invasively in vivo using optical excitation at ultrasonic spatial resolution. For clinical and preclinical linear array imaging systems, conventional delay-and-sum (DAS) beamforming is typically used. However, DAS cardiac PA images are prone to artifacts such as diffuse quasi-static clutter with temporally varying noise-reducing myocardial signal specificity. Typically, multiple frame averaging schemes are utilized to improve the quality of cardiac PAI, which affects the spatial and temporal resolution and reduces sensitivity to subtle PA signal variation. Furthermore, frame averaging might corrupt myocardial oxygen saturation quantification due to the presence of natural cardiac wall motion. In this paper, a spatiotemporal singular value decomposition (SVD) processing algorithm is proposed to reduce DAS PAI artifacts and subsequent enhancement of myocardial signal specificity.Aim: Demonstrate enhancement of PA signals from myocardial tissue compared to surrounding tissues and blood inside the left-ventricular (LV) chamber using spatiotemporal SVD processing with electrocardiogram (ECG) and respiratory signal (ECG-R) gated in vivo murine cardiac PAI.Approach: In vivo murine cardiac PAI was performed by collecting single wavelength (850 nm) photoacoustic channel data on eight healthy mice. A three-dimensional (3D) volume of complex PAI data over a cardiac cycle was reconstructed using a custom ECG-R gating algorithm and DAS beamforming. Spatiotemporal SVD was applied on a two-dimensional Casorati matrix generated using the 3D volume of PAI data. The singular value spectrum (SVS) was then filtered to remove contributions from diffuse quasi-static clutter and random noise. Finally, SVD processed beamformed images were derived using filtered SVS and inverse SVD computations.Results: Qualitative comparison with DAS and minimum variance (MV) beamforming shows that SVD processed images had better myocardial signal specificity, contrast, and target detectability. DAS, MV, and SVD images were quantitatively evaluated by calculating contrast ratio (CR), generalized contrast-to-noise ratio (gCNR), and signal-to-noise ratio (SNR). Quantitative evaluations were done at three cardiac time points (during systole, at end-systole (ES), and during diastole) identified from co-registered ultrasound M-Mode image. Mean CR, gCNR, and SNR values of SVD images at ES were 245, 115.15, and 258.17 times higher than DAS images with statistical significance evaluated with one-way analysis of variance.Conclusions: Our results suggest that significantly better-quality images can be realized using spatiotemporal SVD processing for in vivo murine cardiac PAI.

Spherical-matching hyperbolic-array photoacoustic computed tomography.

Linear-array photoacoustic computed tomography (LA-PACT), for its flexibility and simplicity, has great potential in providing anatomical and functional information of tissues. However, the limited coverage view impedes the LA-PACT obtaining high-quality images. In this study, a photoacoustic tomographic system with a hyperbolic-array transducer was developed for stereoscopic PA imaging of carotid artery. The hyperbolic-array PACT increases the receiving sensitivity for PA signal detection due to its transducer's geometric structure matching with the spherical wave. The control phantom experiment shows that the proposed system can expand the angular coverage of ∼1/3 more than that of the LA-PACT system, and the volumetric PA images of rat's carotid artery demonstrates the potential of the system for carotid artery imaging. Furthermore, volumetric imaging of the human forearm verifies that the system has significant capability in human imaging, which indicates that it has bright prospect for assisting diagnosis in the vascular disease.

Signal and Image Processing in Biomedical Photoacoustic Imaging: A Review

Photoacoustic imaging (PAI) is a powerful imaging modality that relies on the PA effect. PAI works on the principle of electromagnetic energy absorption by the exogenous contrast agents and/or endogenous molecules present in the biological tissue, consequently generating ultrasound waves. PAI combines a high optical contrast with a high acoustic spatiotemporal resolution, allowing the non-invasive visualization of absorbers in deep structures. However, due to the optical diffusion and ultrasound attenuation in heterogeneous turbid biological tissue, the quality of the PA images deteriorates. Therefore, signal and image-processing techniques are imperative in PAI to provide high-quality images with detailed structural and functional information in deep tissues. Here, we review various signal and image processing techniques that have been developed/implemented in PAI. Our goal is to highlight the importance of image computing in photoacoustic imaging.

Multifunctional Nanotheranostic Gold Nanocage/Selenium Core-Shell for PAI-Guided Chemo-Photothermal Synergistic Therapy in vivo.

IntroductionCancer theragnosis involving cancer diagnosis and targeted therapy simultaneously in one integrated system would be a promising solution of cancer treatment. Herein, a convenient and practical cancer theragnosis agent was constructed by combining gold nanocages (AuNCs) covered with selenium and a chitosan (CS) shell (AuNCs/Se) to incorporate the anti-cancer drug doxorubicin (DOX) as a multifunctional targeting nanocomposite (AuNCs/DOX@Se-iRGD) for photoacoustic imaging (PAI)-guided chemo-photothermal synergistic therapy that contributes to enhanced anti-cancer efficacy. The novel design of AuNCs/DOX@Se-iRGD gives the nanocomposite two outstanding properties: (1) AuNCs, with excellent LSPR property in the NIR region, act as a contrast agent for enhanced PAI and photothermal therapy (PTT); (2) Se acts as an anti-cancer nanoagent and drug delivery cargo.MethodsThe photothermal performance of these nanocomposites was evaluated in different concentrations with laser powder densities. These nanocomposites were also incubated in pH 5.3, 6.5, 7.4 PBS and NIR laser to study their drug release ability. The cellular uptake was studied by measuring the Se and Au concentrations inside the cells using inductively coupled plasma-mass spectrometry (ICP-MS). Besides, in vitro and in vivo anti-tumor activity were carried out by cytotoxicity assay MTT and tumor model nude mice, respectively. As for imaging, the PA value and images of these nanocomposites accumulated in the tumor site were sequentially collected at specific time points for 48 h.Results and DiscussionThe prepared AuNCs/DOX@Se-iRGD showed excellent biocompatibility and physiological stability in different media. In vivo results indicated that the targeting nanocomposite presented the strongest contrast-enhanced PAI signals, which could provide contour and location information of tumor, 24 h after intravenous injection. Likewise, the combined treatment of chemo- and photothermal synergistic therapy significantly inhibited tumor growth when compared with the two treatments carried out separately and showed negligible acute toxicity to the major organs.ConclusionThis study demonstrates that AuNCs/DOX@Se-iRGD has great prospect to become a multifunctional anti-tumor nanosystem for PAI-guided chemo- and photothermal synergistic therapy.

Nilai Contrast to Noise Ratio (CNR) Radiograf Thorax PA antara menggunakan Grid dengan tanpa Menggunakan Grid

Background: Chest radiographic examination often does not use a grid even though the thorax is an object that has a thickness of more than 10 cm so it must use a grid. This study aims to determine the differences and the degree of change in Contrast to Noise Ratio on PA radiographs between using a grid and without using a grid.Methods: This type of research is a pre-experimental quantitative. The research subject is a radiological image of PA thorax made using the grid (50 patients) and without using the grid (patient). The image is analyzed by pixel value using Dicom softwareResults: There is a difference in contrast values on the PA radiographs between those using the Grid and without using the Grid (p-value 0.001). The average value of the contrast on the chest radiograph using a Grid is 2283.60, while the one without using a Grid is 1878.58. Noise value also shows that there is a difference between chest radiographs of PA images using Grid without using Grid (p-value = 0.001). The average thorax photo noise using Grid is 25.32, paired using Grid is 17.84. Statistical test on the value of Contrast to Noise Ratio (CNR) shows that there is a difference between radiographs of PA chest radiography using Grid without Grid (p-value 0.001). The average CNR radiograph of the PA thorax PA using Grid is 100.79, while the CNR value of the radiograph of thorax PA without using Grid is 125.62.Conclusions: There is a Contrast difference between using a grid and without using a grid (p-value 0.001). There is a Noise difference in PA radiographs between using a grid and without using a grid (p-value = 0.001). There is a difference in Contrast to Noise Ratio on the PA chest radiograph between using a grid and without using a grid (p-value 0.001).

Photoacoustic imaging for three-dimensional visualization and delineation of basal cell carcinoma in patients

BackgroundPhotoacoustic (PA) imaging is an emerging non-invasive biomedical imaging modality that could potentially be used to determine the borders of basal cell carcinomas (BCC) preoperatively in order to reduce the need for repeated surgery. MethodsTwo- and three-dimensional PA images were obtained by scanning BCCs using 59 wavelengths in the range 680–970 nm. Spectral unmixing was performed to visualize the tumor tissue distribution. Spectral signatures from 38 BCCs and healthy tissue were compared ex vivo. Results and discussionThe PA spectra could be used to differentiate between BCC and healthy tissue ex vivo (p < 0.05). Spectral unmixing provided visualization of the overall architecture of the lesion and its border. ConclusionPA imaging can be used to differentiate between BCC and healthy tissue and can potentially be used to delineate tumors prior to surgical excision.

Presentation Attack Face Image Generation Based on a Deep Generative Adversarial Network.

Although face-based biometric recognition systems have been widely used in many applications, this type of recognition method is still vulnerable to presentation attacks, which use fake samples to deceive the recognition system. To overcome this problem, presentation attack detection (PAD) methods for face recognition systems (face-PAD), which aim to classify real and presentation attack face images before performing a recognition task, have been developed. However, the performance of PAD systems is limited and biased due to the lack of presentation attack images for training PAD systems. In this paper, we propose a method for artificially generating presentation attack face images by learning the characteristics of real and presentation attack images using a few captured images. As a result, our proposed method helps save time in collecting presentation attack samples for training PAD systems and possibly enhance the performance of PAD systems. Our study is the first attempt to generate PA face images for PAD system based on CycleGAN network, a deep-learning-based framework for image generation. In addition, we propose a new measurement method to evaluate the quality of generated PA images based on a face-PAD system. Through experiments with two public datasets (CASIA and Replay-mobile), we show that the generated face images can capture the characteristics of presentation attack images, making them usable as captured presentation attack samples for PAD system training.