Significance: Full-field optical angiography is critical for vascular disease research and clinical diagnosis. Existing methods struggle to improve the temporal and spatial resolutions simultaneously.
Aim: Spatiotemporal absorption fluctuation imaging (ST-AFI) is proposed to achieve dynamic blood flow imaging with high spatial and temporal resolutions.
Approach: ST-AFI is a dynamic optical angiography based on a low-coherence imaging system and U-Net. The system was used to acquire a series of dynamic red blood cell (RBC) signals and static background tissue signals, and U-Net is used to predict optical absorption properties and spatiotemporal fluctuation information. U-Net was generally used in two-dimensional blood flow segmentation as an image processing algorithm for biomedical imaging. In the proposed approach, the network simultaneously analyzes the spatial absorption coefficient differences and the temporal dynamic absorption fluctuation.
Results: The spatial resolution of ST-AFI is up to 4.33 μm, and the temporal resolution is up to 0.032 s. In vivo experiments on 2.5-day-old chicken embryos were conducted. The results demonstrate that intermittent RBCs flow in capillaries can be resolved, and the blood vessels without blood flow can be suppressed.
Conclusions: Using ST-AFI to achieve convolutional neural network (CNN)-based dynamic angiography is a novel approach that may be useful for several clinical applications. Owing to their strong feature extraction ability, CNNs exhibit the potential to be expanded to other blood flow imaging methods for the prediction of the spatiotemporal optical properties with improved temporal and spatial resolutions.
We propose a logic optical projection tomography (LOPT) method to realize full-view, three-dimensional (3-D) shape parameters measurement and visualization for opaque objects. The main innovation of LOPT is use of a logic process to obtain high-contrast and homogeneous boundary projection signals. According to the reconstructed 2-D cross-section images, the structure characteristic points in each slice are independently extracted and combined to produce a full-view 3-D image. Further, the structural shape parameters of individual parts of object such as the inscribed cylinder, center line, and double threads are obtained and visualized simultaneously. Our experimental results demonstrate that LOPT can be potentially developed as an economical optical measurement and visualization tool for some industrial application.
The ability of combining serum surface-enhanced Raman spectroscopy (SERS) with support vector machine (SVM) for improving classification esophageal cancer patients from normal volunteers is investigated. Two groups of serum SERS spectra based on silver nanoparticles (AgNPs) are obtained: one group from patients with pathologically confirmed esophageal cancer (n=30 ) and the other group from healthy volunteers (n=31 ). Principal components analysis (PCA), conventional SVM (C-SVM) and conventional SVM combination with PCA (PCA-SVM) methods are implemented to classify the same spectral dataset. Results show that a diagnostic accuracy of 77.0% is acquired for PCA technique, while diagnostic accuracies of 83.6% and 85.2% are obtained for C-SVM and PCA-SVM methods based on radial basis functions (RBF) models. The results prove that RBF SVM models are superior to PCA algorithm in classification serum SERS spectra. The study demonstrates that serum SERS in combination with SVM technique has great potential to provide an effective and accurate diagnostic schema for noninvasive detection of esophageal cancer.
Raman spectroscopy (RS) and a genetic algorithm (GA) were applied to distinguish nasopharyngeal cancer (NPC) from normal nasopharyngeal tissue. A total of 225 Raman spectra are acquired from 120 tissue sites of 63 nasopharyngeal patients, 56 Raman spectra from normal tissue and 169 Raman spectra from NPC tissue. The GA integrated with linear discriminant analysis (LDA) is developed to differentiate NPC and normal tissue according to spectral variables in the selected regions of 792-805, 867-880, 996-1009, 1086-1099, 1288-1304, 1663-1670, and 1742-1752 cm−1 related to proteins, nucleic acids and lipids of tissue. The GA-LDA algorithms with the leave-one-out cross-validation method provide a sensitivity of 69.2% and specificity of 100%. The results are better than that of principal component analysis which is applied to the same Raman dataset of nasopharyngeal tissue with a sensitivity of 63.3% and specificity of 94.6%. This demonstrates that Raman spectroscopy associated with GA-LDA diagnostic algorithm has enormous potential to detect and diagnose nasopharyngeal cancer.
In present work, we studied the effect of optical clearing on porcine skin in vitro with glycerol by Raman microspectroscopy, denoted as RM, at various time intervals of 0, 15, 30, 45, 60, and 75 min respectively. The results showed that the addition of glycerol significantly improved the depth of RM measurement, and enhanced the recovery of skin tissue Raman spectra that were not overlapped with the glycerol Raman spectra over time. Moreover, it was found that the Raman signals resembled the native spectrum of the molecules in porcine skin with a negligible frequency shift. Furthermore, we evaluated the extent of optical clearing in porcine skin by utilizing various concentrations of 40%, 60%, and 80% glycerol solution. The results demonstrated that with the increase of concentration of glycerol, the optical clearing of porcine skin was much improved.
Previous studies have demonstrated the ultrasound-induced skin optical clearing enhancement with topical application of 60% glycerol (G) on in vitro porcine skin and in vivo human skin. Our purpose was to find the relation between the effect of optical skin clearing and different concentrations of glycerol and to find more effective ultrasound-glycerol combinations on optical skin clearing. The enhancement effect of ultrasound [Sonophoresis (SP) delivery] in combination with 40% G, 60% G, and 80% G on in vitro human skin optical clearing was investigated. Light imaging depths of skin were measured using optical coherence tomography. Different concentrations of glycerol and ultrasound with a frequency of 1 MHz and an intensity of 0.5 W/cm2 was simultaneously applied for 15 min. The results show that with the increase of concentration of glycerol, the optical clearing of skin is much improved. Optical clearing capability of glycerol was more enhanced with simultaneous application of ultrasound compared with glycerol alone. The attenuation coefficients of skin tissues after application of 40% G/SP, 60% G/SP, and 80% G/SP decreased approximately 11.8%, 18.5%, and 20.0% at 15 min compared with 40% G, 60% G, and 80% G alone, respectively. The greatest decrease in attenuation coefficients at 60 min was approximately 52.3% and 63.4% for 80% G (without ultrasound) and 80% G/SP (with ultrasound), respectively, which are 2.1-fold and 2.6-fold to that in the 40% G.
Noninvasive tumor imaging could lead to the early detection and timely treatment of cancer. Previous investigations
have suggested that optical coherence tomography (OCT) is an ideal diagnostic tool distinguishing normal tissues from
tumor tissues based on structural imaging because of the high resolution. In the study, the capability of OCT for
functional imaging of normal and tumor tissues based on time and depth resolved quantification of the permeability of
biomolecules through these tissues is investigated. An OCT system at 830 nm central wavelength was used in this study.
Diffusion of 20% aqueous solution of glucose was monitored and quantified in normal stomach tissues and tumor tissues
using OCT. The orthotopic graft model of gastric cancer in nude mice was used. Permeability coefficients were
calculated as a function of time and tissue depth. The permeability coefficient was (9.44±0.42) ×10-6 cm/s in normal
stomach tissues and (5.32±0.17)×10-5 cm/s in tumor tissues. The tumor tissues had a higher permeability coefficient
compared to normal tissues. From the experimental results, it is found that the accurate and sensitive assessment of the
permeability coefficients of normal and tumor tissues offer an effective OCT image method for clinical diagnosis and
detection of tumor tissues.
Noninvasive tumor imaging could lead to the early detection and timely treatment of cancer. Optical coherence tomography (OCT) has been reported as an ideal diagnostic tool for distinguishing tumor tissues from normal tissues based on structural imaging. In this study, the capability of OCT for functional imaging of normal and tumor tissues based on time- and depth-resolved quantification of the permeability of biomolecules through these tissues is investigated. The orthotopic graft model of gastric cancer in nude mice is used, normal and tumor tissues from the gastric wall are imaged, and a diffusion of 20% aqueous solution of glucose in normal stomach tissues and gastric tumor tissues is monitored and quantified as a function of time and tissue depth by an OCT system. Our results show that the permeability coefficient is (0.94±0.04)×10−5 cm/s in stomach tissues and (5.32±0.17)×10−5 cm/s in tumor tissues, respectively, and that tumor tissues have a higher permeability coefficient compared to normal tissues in optical coherence tomographic images. From the results, it is found that the accurate and sensitive assessment of the permeability coefficients of normal and tumor tissues offers an effective OCT image method for detection of tumor tissues and clinical diagnosis.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.