Contrast In Optical Coherence Tomography Images Research Articles

Assessment of chitosan-coated zinc cobalt ferrite nanoparticle as a multifunctional theranostic platform facilitating pH-sensitive drug delivery and OCT image contrast enhancement

Colorectal cancer (CC) is one of the most predominant malignancies in the world, with the current treatment regimen consisting of surgery, radiation therapy, and chemotherapy. Chemotherapeutic drugs, such as 5-fluorouracil (5-FU), have gained popularity as first-line antineoplastic agents against CC but have several drawbacks, including variable absorption through the gastrointestinal tract, inconsistent liver metabolism, short half-life, toxicological reactions in several organ systems, and others. Therefore, herein, we develop chitosan-coated zinc-substituted cobalt ferrite nanoparticles (CZCFNPs) for the pH-sensitive (triggered by chitosan degradation within acidic organelles of cells) and sustained delivery of 5-FU in CC cells in vitro. Additionally, the developed nanoplatform served as an excellent exogenous optical coherence tomography (OCT) contrast agent, enabling a significant improvement in the OCT image contrast in a CC tissue phantom model with a biomimetic microvasculature. Further, this study opens up new possibilities for using OCT for the non-invasive monitoring and/or optimization of magnetic targeting capabilities, as well as real-time tracking of magnetic nanoparticle-based therapeutic platforms for biomedical applications. Overall, the current study demonstrates the development of a CZCFNP-based theranostic platform capable of serving as a reliable drug delivery system as well as a superior OCT exogenous contrast agent for tissue imaging.

Natural Fat Nanoemulsions for Enhanced Optical Coherence Tomography Neuroimaging and Tumor Imaging in the Second Near-Infrared Window.

Optical coherence tomography (OCT) imaging mainly uses backscattered light to visualize the structural and functional information on biological tissues. In particular, OCT angiography can not only map the capillary networks but also capture the blood flow in the tissue microenvironment, making it a good candidate for neuroimaging and tumor imaging in vivo and in real time. To further improve the detection accuracy of cancer or brain disorders, it is essential to develop a natural and nontoxic contrast agent for enhanced OCT imaging in the second near-infrared (NIR-II) window. In this study, a superior biocompatible and highly scattering NIR-II fat nanoemulsion was constructed to improve OCT imaging contrast and depth for monitoring the vascular network changes of the cerebral cortex or tumor. In vivo experimental results demonstrated that a natural fat nanoemulsion can serve as an excellent probe for enhanced OCT neuroimaging and tumor imaging.

RMAP-ResNet: Segmentation of brain tumor OCT images using residual multicore attention pooling networks for intelligent minimally invasive theranostics

Background and objectiveThe occurrence of brain tumors seriously affects patients both mentally and physically, reducing their quality of life. Automatic recognition and segmentation of tumor boundaries are essential for computer-aided diagnosis and treatment. While optical coherence tomography (OCT) has been widely employed in the detection and analysis fundus lesions and vascular segmentation due to its high resolution and real-time imaging advantages, the segmentation of brain tumor OCT images based on deep neural network has not been studied. However, despite the encoding and decoding structure based on deep learning has achieved good results in medical image segmentation, these models still face limitations in accurately segmenting tumor OCT images due to variations in tumor shapes, sizes, and numbers, and the low contrast of OCT images. Accurate segmentation of tumor tissue contours is crucial as the absence of this mechanism hampers the effective application of OCT imaging methods for brain tumor diagnosis and treatment in clinical practice. Therefore, we propose a novel neural network that can accurately segment brain tumors and their residual tissues in OCT images. MethodsIn this study, we propose a novel residual multi-core attention pooling network (RMAP ResNet) for the segmentation of tumorous and its residual tissue. The RMAP module primarily relies on multiple associative effective receptive fields. These fields enable the detection of targets of various sizes. The module also incorporates an attention structure to adjust connection weights, suppressing irrelevant information and emphasizing the characteristics of tumor OCT images. This process restores the contextual dependencies. ResultsWe validated our proposed RMAP ResNet method on the dataset of mouse tumor OCT imaging obtained using the sweep source OCT imaging system. The experimental results demonstrate that RMAP ResNet achieves superior performance in tumor tissue segmentation. The proposed method improves the quality of tumor segmentation for various shapes and sizes, leading to superior results. RMAP ResNet achieved Dice and IoU values of 94.78% and 90.58%, respectively, confirming the effectiveness and advancement of our proposed technology. ConclusionsOur proposed method addresses the crucial issue of the limited use of the OCT imaging modality in tumor resection surgery. It overcomes the challenge of visually identifying the tumor boundary in OCT modality imaging, where physicians using the naked eye may encounter difficulties. This study has potential applications in the fields of surgical navigation and intelligent minimally invasive treatment of brain tumors.

Multimodal Diagnostics of Changes in Rat Lungs after Vaping.

(1) Background: The use of electronic cigarettes has become widespread in recent years. The use of e-cigarettes leads to milder pathological conditions compared to traditional cigarette smoking. Nevertheless, e-liquid vaping can cause morphological changes in lung tissue, which affects and impairs gas exchange. This work studied the changes in morphological and optical properties of lung tissue under the action of an e-liquid aerosol. To do this, we implemented the "passive smoking" model and created the specified concentration of aerosol of the glycerol/propylene glycol mixture in the chamber with the animal. (2) Methods: In ex vivo studies, the lungs of Wistar rats are placed in the e-liquid for 1 h. For in vivo studies, Wistar rats were exposed to the e-liquid vapor in an aerosol administration chamber. After that, lung tissue samples were examined ex vivo using optical coherence tomography (OCT) and spectrometry with an integrating sphere. Absorption and reduced scattering coefficients were estimated for the control and experimental groups. Histological sections were made according to the standard protocol, followed by hematoxylin and eosin staining. (3) Results: Exposure to e-liquid in ex vivo and aerosol in in vivo studies was found to result in the optical clearing of lung tissue. Histological examination of the lung samples showed areas of emphysematous expansion of the alveoli, thickening of the alveolar septa, and the phenomenon of plasma permeation, which is less pronounced in in vivo studies than for the exposure of e-liquid ex vivo. E-liquid aerosol application allows for an increased resolution and improved imaging of lung tissues using OCT. Spectral studies showed significant differences between the control group and the ex vivo group in the spectral range of water absorption. It can be associated with dehydration of lung tissue owing to the hyperosmotic properties of glycerol and propylene glycol, which are the main components of e-liquids. (4) Conclusions: A decrease in the volume of air in lung tissue and higher packing of its structure under e-liquid vaping causes a better contrast of OCT images compared to intact lung tissue.

Optical coherence tomography of human fetal membrane sub-layers during loading.

Fetal membranes have important mechanical and antimicrobial roles in maintaining pregnancy. However, the small thickness (<800 µm) of fetal membranes places them outside the resolution limits of most ultrasound and magnetic resonance systems. Optical imaging methods like optical coherence tomography (OCT) have the potential to fill this resolution gap. Here, OCT and machine learning methods were developed to characterize the ex vivo properties of human fetal membranes under dynamic loading. A saline inflation test was incorporated into an OCT system, and tests were performed on n = 33 and n = 32 human samples obtained from labored and C-section donors, respectively. Fetal membranes were collected in near-cervical and near-placental locations. Histology, endogenous two photon fluorescence microscopy, and second harmonic generation microscopy were used to identify sources of contrast in OCT images of fetal membranes. A convolutional neural network was trained to automatically segment fetal membrane sub-layers with high accuracy (Dice coefficients >0.8). Intact amniochorion bilayer and separated amnion and chorion were individually loaded, and the amnion layer was identified as the load-bearing layer within intact fetal membranes for both labored and C-section samples, consistent with prior work. Additionally, the rupture pressure and thickness of the amniochorion bilayer from the near-placental region were greater than those of the near-cervical region for labored samples. This location-dependent change in fetal membrane thickness was not attributable to the load-bearing amnion layer. Finally, the initial phase of the loading curve indicates that amniochorion bilayer from the near-cervical region is strain-hardened compared to the near-placental region in labored samples. Overall, these studies fill a gap in our understanding of the structural and mechanical properties of human fetal membranes at high resolution under dynamic loading events.

Latent fingerprint imaging by spectroscopic optical coherence tomography

Optical coherence tomography (OCT) is a non-contact and non-invasive optical method for evaluating semitransparent and scattering objects. Its unique features, such as non-destructive 3D measurements of tested objects with a fast scanning rate, make this technique interesting for latent fingerprint reading, which is the subject of this paper. So far, OCT has not found widespread use for reading fingerprints directly from surfaces due to its insufficient axial resolution. This problem has been overcome by applying spectroscopic analysis to the OCT measurements, which is based on retrieving the spatially resolved spectral characteristics of the recorded backscattered light directly from the OCT measurement data. The spectroscopic analysis is very sensitive to thin film thickness variations, improving the readability of the latent fingerprints by OCT, which is reported here as well. This study includes a description of spectroscopic analysis in combination with OCT and indicates the benefits for thin film evaluation, in particular, latent fingerprints. The example of latent fingerprint OCT measurements enhanced by spectroscopic analysis has been shown, as well as a brief discussion of the method's applicability. Finally, improving fingerprint OCT imaging contrast and readability by applying spectroscopic analysis have been confirmed.

An Ophthalmic Evaluation of Central Serous Chorioretinopathy

Nowadays in the medical field, imaging techniques such as Optical Coherence Tomography (OCT) are mainly used to identify retinal diseases. In this paper, the Central Serous Chorio Retinopathy (CSCR) image is analyzed for various stages and then compares the difference between CSCR before as well as after treatment using different application methods. The first approach, which was focused on image quality, improves medical image accuracy. An enhancement algorithm was implemented to improve the OCT image contrast and denoise purpose called Boosted Anisotropic Diffusion with an Unsharp Masking Filter (BADWUMF). The classifier used here is to figure out whether the OCT image is a CSCR case or not. 150 images are checked for this research work (75 abnormal from Optical Coherence Tomography Image Retinal Database, in-house clinical database, and 75 normal images). This article explicitly decides that the approaches suggested aid the ophthalmologist with the precise retinal analysis and hence the risk factors to be minimized. The total precision is 90 percent obtained from the Two Class Support Vector Machine (TCSVM) classifier and 93.3 percent is obtained from Shallow Neural Network with the Powell-Beale (SNNWPB) classifier using the MATLAB 2019a program.

Au/Si Bilayer Nanodisks with Tunable Localized Surface Plasmon Resonance for Optical Coherence Tomography in the Second Near‐Infrared Window

Bioimaging in the second near‐infrared (NIR‐II) window can help to obtain high‐resolution images and a high penetration depth. This study proposes an Au/Si bilayer plasmonic nanodisk (Au/Si ND) that has a resonance wavelength in the NIR‐II window caused by Si ND stacking on top of the Au ND with a resonance wavelength in the first near‐infrared window; the Si ND has a high refractive index. Au/Si NDs are physically synthesized using nanoimprint lithography and vacuum deposition. Optical coherence tomography (OCT) imaging is performed using synthesized Au/Si NDs as OCT contrast agents in the NIR‐II window. Due to the 2D circular shape and its remarkable response to random incident light, the Au/Si NDs exhibit approximately 250‐fold greater OCT signal intensity than do commercial 1D Au nanorods, as well as fourfold greater penetration depth and improved OCT image contrast.

Monitoring the topical delivery of ultrasmall gold nanoparticles using optical coherence tomography

Optical coherence tomography (OCT) is a promising imaging modality for skin cancer diagnosis. However, this capability has been hindered by the low contrast between normal and neoplastic tissue. To overcome this limitation, gold nanoparticles have been used to enhance the contrast in OCT images and are topically administered to reduce the risk of systematic side effects associated with intravenous injection. To ensure efficient penetration and distribution of the nanoparticles, an enhanced delivery strategy is required. In this porcine study, we assessed two delivery methods: (a) using dimethyl sulfoxide (DMSO) and (b) via sonophoresis. The gold nanoparticles were topically applied on pig skin before evaluating DMSO and sonophoresis as penetration enhancers in topical administration. The OCT images were taken from the same locations to monitor signal change. The combination of DMSO and sonophoresis is an effective method to enhance the penetration and diffusion rate of nanoparticles during topical administration. Topical administration of nanoparticles is advantageous in dermatological applications. Nevertheless, efficient topical delivery remains a challenge. DMSO and sonophoresis can be used as two effective approaches to enhance topical delivery of nanoparticles.

Depth-Resolved Enhanced Spectral-Domain OCT Imaging of Live Mammalian Embryos Using Gold Nanoparticles as Contrast Agent.

High-resolution and real-time visualization of the morphological changes during embryonic development are critical for studying congenital anomalies. Optical coherence tomography (OCT) has been used to investigate the process of embryogenesis. However, the structural visibility of the embryo is decreased with the depth due to signal roll-off and high light scattering. To overcome these obstacles, in this study, combined is a spectral-domain OCT (SD-OCT) with gold nanorods (GNRs) for 2D/3D imaging of live mouse embryos. Inductively coupled plasma mass spectrometry is used to confirm that GNRs can be effectively delivered to the embryos during ex vivo culture. OCT signal, image contrast, and penetration depth are all enhanced on the embryos with GNRs. These results show that after GNR treatment, more accurate spatial localization and better contrasting of the borders among organs can be observed on E9.5 and E10.5 mouse embryos. Furthermore, the strong optical absorbance of GNRs results in much clearer 3D images of the embryos, which can be used for calculating the heart areas and volumes of E9.5 and E10.5 embryos. These findings provide a promising strategy for monitoring organ development and detecting congenital structural abnormalities in mice.

Understanding optical reflectance contrast for real-time characterization of epithelial precursor lesions.

Detecting early‐stage epithelial cancers and their precursor lesions are challenging as lesions could be subtle and focally or heterogeneously distributed over large mucosal areas. Optical coherence tomography (OCT) that enables wide‐field imaging of subsurface microstructures in vivo is a promising screening tool for epithelial diseases. However, its diagnostic capability has not been fully appreciated since the optical reflectance contrast is poorly understood. We investigated the back‐scattered intensities from clustered or packed nanometer scale intracellular scatterers using finite‐difference time‐domain method and 1‐μm resolution form of OCT, and uncovered that there existed correlations between the reflectance contrasts and the ultrastructural clustering or packing states of these scatterers, which allows us to interpret the physiological state of the cells. Specifically, both polarized goblet cells and foveolar cells exhibited asymmetric reflectance contrast, but they could be differentiated by the optical intensity of the mucin cup due to the different ultrastructural make‐ups of the mucin granules; keratinocytes could demonstrate varied cytoplasmic intensity and their cytoplasmic contrast was closely correlated with the packing state of keratin filaments. Further preliminary study demonstrated that these new understandings of OCT image contrast enables the characterization of precancerous lesions, which could complement the current morphology‐based criteria in realizing “virtual histology” and would have a profound impact for the screening and surveillance of epithelial cancers.

Complex decorrelation averaging in optical coherence tomography: a way to reduce the effect of multiple scattering and improve image contrast in a dynamic scattering medium.

We demonstrate that complex decorrelation averaging can reduce the effect of multiple scattering and improve optical coherence tomography (OCT) imaging contrast. Complex decorrelation averaging calculates the product of an A-scan and the complex conjugate of a subsequent A-scan. The resultant signal is the product of the amplitudes and the phase difference. All these resulting complex signals at a particular location are then averaged. We take advantage of the fact that complex averaging, in contrast to conventional magnitude averaging, is sensitive to phase decorrelation. Sample motion that increases signal phase variance results in lower signal magnitude after complex averaging. Such motion preferentially results in a faster decorrelation of the multiple scattering signal when compared to the single scattering signal with each scattering event spreading the phase. This indicates that we may reduce multiple scattering by implementing complex decorrelation averaging to preferentially reduce the magnitude of the multiply scattered light signal in OCT images. By adjusting the time between phase-differenced A-scans, one can regulate the amount of measured decorrelation. We have performed experiments on liquid phantoms that give experimental evidence for this hypothesis. A substantial improvement in OCT image contrast using complex decorrelation averaging is demonstrated.

Retroreflective-type Janus microspheres as a novel contrast agent for enhanced optical coherence tomography.

Optical coherence tomography (OCT) is a well-developed technology that utilizes near-infrared light to reconstruct three-dimensional images of biological tissues with micrometer resolution. Improvements of the imaging contrast of the OCT technique are able to further widen its extensive biomedical applications. In this study, Janus microspheres were developed and used as a positive contrast agent for enhanced OCT imaging. Phantom and ex vivo liver tissue experiments as well as in vivo animal tests were conducted, which validated that Janus microspheres, as a novel type of OCT tracer, were very effective in improving the OCT imaging contrast. Working principle and SEM image of Janus microsphere (top). Enhanced OCT imaging (bottom) of Janus microspheres in zebrafish stomach (blue dash line) and sinusoids (green arrows) of nude liver.

OCT Study of Optical Clearing of Muscle Tissue in vitro with 40% Glucose Solution

The technique of -optical clearing of biological tissues- is aimed at improving the quality of visualization of structures hidden deep in tissue. In this study, we measured the diffusion coefficient of glucose in bovine skeletal muscle tissue by optical coherence tomography (OCT) in vitro and determined changes that took place in the imaging contrast of muscle fibers, the optical depth of coherent probing, and detection under the influence of aqueous 40% solution of glucose. It was shown that, within 90 min, when the depth of coherent probing increased by 14%, the contrast of OCT images increased fourfold and the depth of coherent detection of structural elements of the tissue increased by 2.4 times. The diffusion coefficient of glucose in the muscle tissue was (2.98 ± 0.94) × 10-6 cm2/s.

Anti-biofouling conducting polymer nanoparticles as a label-free optical contrast agent for high resolution subsurface biomedical imaging

Optical coherence tomography (OCT) is a modern high resolution subsurface medical imaging technique. Herein we describe: (i) the synthesis of a thiophene-functionalized oligo(ethylene glycol) methacrylate (OEGMA)-based statistical copolymer, denoted poly(2TMOI–OEGMA); (ii) the preparation of sterically-stabilized polypyrrole (PPy) nanoparticles of approximately 60 nm diameter; (iii) the evaluation of these nanoparticles as a NIR-absorbing optical contrast agent for high-resolution OCT imaging. We show that poly(2TMOI–OEGMA)-stabilized PPy nanoparticles exhibit similar optical properties to poly(vinyl alcohol) (PVA)-stabilized PPy nanoparticles of comparable size prepared using commercially available PVA. Spectroscopic measurements and Mie calculations indicate that both types of PPy nanoparticles strongly absorb NIR radiation above 1000 nm, suggesting their potential use as OCT contrast agents. In vitro OCT studies indicate that both types of PPy nanoparticles reduce NIR backscattering within homogeneous intralipid tissue phantoms, offering almost identical contrast performance in this medium. However, PVA-stabilized PPy nanoparticles became colloidally unstable when dispersed in physiological buffer and immersed in a solid biotissue phantom and hence failed to generate a strong contrast effect. In contrast, the poly(2TMOI–OEGMA)-stabilized PPy nanoparticles remained well-dispersed and hence exhibited a strong rapid onset contrast effect within the biotissue phantom under identical physiological conditions. Ex vivo studies performed on excised chicken and porcine skin tissue demonstrated that topical administration of a low concentration of poly(2TMOI–OEGMA)-stabilized PPy nanoparticles rapidly enhances OCT image contrast in both cases, allowing key tissue features to be readily identified.

Intracoronary imaging using attenuation-compensated optical coherence tomography allows better visualisation of coronary artery diseases

To allow an accurate diagnosis of coronary artery diseases by enhancing optical coherence tomography (OCT) images of atheromatous plaques using a novel automated attenuation compensation technique. One of the major drawbacks of coronary OCT imaging is the rapid attenuation of the OCT signal, limiting penetration in tissue to only few millimetres. Visualisation of deeper anatomy is however critical for accurate assessment of plaque burden in-vivo. A compensation algorithm, previously developed to correct for light attenuation in soft tissues and to enhance contrast in ophthalmic OCT images, was applied to intracoronary plaque imaging using spectral-domain OCT. Application of the compensation algorithm significantly increased tissue contrast in the vessel wall and atherosclerotic plaque boundaries. Contrast enhancement allows a better differentiation of plaque morphology, which is particularly important for the identification of lipid rich fibro atheromatous plaques and to guide decision on treatment strategy. The analysis of arterial vessel structure clinically captured with OCT is improved when used in conjunction with automated attenuation compensation. This approach may improve the OCT-based interpretation of coronary plaque morphology in clinical practice.

Shadow Removal and Contrast Enhancement in Optical Coherence Tomography Images of the Human Optic Nerve Head

To improve the quality of optical coherence tomography (OCT) images of the optic nerve head (ONH). Two algorithms were developed, one to compensate for light attenuation and the other to enhance contrast in OCT images. The former was borrowed from developments in ultrasound imaging and was proven suitable with either time- or spectral-domain OCT. The latter was based on direct application of pixel intensity exponentiation. The performances of these two algorithms were tested on spectral-domain OCT images of four adult ONHs. Application of the compensation algorithm significantly reduced the intralayer contrast (from 0.74 ± 0.16 to 0.17 ± 0.12; P < 0.001), indicating successful blood vessel shadow removal. Furthermore, compensation dramatically improved the visibility of deeper ONH tissues, such as the peripapillary sclera and lamina cribrosa. Application of the contrast-enhancement algorithm significantly increased the interlayer contrast (from 0.48 ± 0.22 to a maximum of 0.89 ± 0.05; P < 0.001) and thus allowed a better differentiation of tissue boundaries. Contrast enhancement was robust only when compensation was considered. The proposed algorithms are simple and can significantly improve the quality of ONH images clinically captured with OCT. This study has important implications, as it will help improve our ability to perform automated segmentation of the ONH; quantify the morphometry and biomechanics of ONH tissues in vivo; and identify potential risk indicators for glaucoma.

Added soft tissue contrast using signal attenuation and the fractal dimension for optical coherence tomography images of porcine arterial tissue

Optical coherence tomography (OCT) images of left-descending coronary tissues harvested from three porcine specimens were acquired with a home-build swept-source OCT setup. Despite the fact that OCT is capable of acquiring high resolution circumferential images of vessels, many distinct histological features of a vessel have comparable optical properties leading to poor contrast in OCT images. Two classification methods were tested in this report for the purpose of enhancing contrast between soft-tissue components of porcine coronary vessels. One method involved analyzing the attenuation of the OCT signal as a function of light penetration into the tissue. We demonstrated that by analyzing the signal attenuation in this manner we were able to differentiate two media sub-layers with different orientations of the smooth muscle cells. The other classification method used in our study was fractal analysis. Fractal analysis was implemented in a box-counting (fractal dimension) image-processing code and was used as a tool to differentiate and quantify variations in tissue texture at various locations in the OCT images. The calculated average fractal dimensions had different values in distinct regions of interest (ROI) within the imaged coronary samples. When compared to the results obtained by using the attenuation of the OCT signal, the method of fractal analysis demonstrated better classification potential for distinguishing amongst the tissue ROI.

Improved contrast in clinical imaging

Optical coherence tomography (OCT) is a standard tool for detailed twoand three-dimensional noninvasive analysis of retinal diseases in ophthalmology. It is also a promising research instrument, permitting early tumor diagnosis in skin and bladder tissue. OCT provides high-resolution images of biological tissue using the interference between incident and returning (reflected or backscattered) light1 to obtain structural information that can be used to distinguish between a skin tumor and healthy skin. A particularly important use is to distinguish benign and malignant tumors by means of ‘basement membrane invasion.’ If the tumor has spread beyond the epithelium (outer layer) of a structure in the body through the basement membrane (middle layer), and is intruding into the underlying connective tissue, it must be cut out. However, the structural contrast is not always sufficient to result in a meaningful diagnosis. So-called exogenous contrast agents are frequently used to increase the structural contrast in OCT images. Microspheres, nanoshells, nanorods, microbubbles, or other contrast agents are inserted into the tissue and increase the image intensity within specific regions of interest.2 They are, however, difficult to administer and possibly toxic, and so different approaches are needed.3 A common alternative to contrast agents relies on analyzing the frequency dependence of backscattered light. This can improve differentiation of tissue structures, but this ‘spectroscopic-OCT’ method requires computationally expensive time-frequency analysis,3 making it too slow for significant use with patients. Furthermore, this technique analyzes the wavelength dependence of the sample only within one distinct spectral regime. Higher wavelength dependences can be exploited by simultaneously imaging in two bands4 and using color to represent the difference between the two resulting images. This is computationally inexpensive and this method of generating Figure 1. Experimental setup. FC: Fiber collimator. BS: Beamsplitter. G: Diffraction grating. InGaAs: Indium gallium arsenide. Si: Silicon.

Gold Nanocages for Cancer Detection and Treatment

Gold nanocages represent a novel class of biocompatible vectors with potential applications in drug delivery, tumor/tissue imaging and photothermal therapy. They are prepared through the galvanic-replacement reaction between Ag nanostructures and HAuCl(4). By controlling the amount of HAuCl(4) added, we can tune the surface-plasmon resonance peaks of the Au nanocages into the near-infrared, where the attenuation of light by blood and soft tissue is relatively low. Here, we highlight recent advances in the synthesis and utilization of Au nanocages for cancer detection and treatment. We have tailored the optical properties of Au nanocages for use as contrast agents in optical coherence tomography and as transducers for the selective photothermal ablation of cancer cells. Our results show improved optical coherence tomography image contrast when Au nanocages are added to tissue phantoms as well as the selective photothermal destruction of breast cancer cells in vitro when immunotargeted Au nanocages are used.