TY - JOUR AB - SIGNIFICANCE: Shortwave-infrared (SWIR) imaging is reported to yield better contrast in fluorescence-guided surgery than near-infrared (NIR) imaging, due to a reduction in scattering. This benefit of SWIR was shown in animal studies, however not yet in clinical studies with patient samples. AIM: We investigate the potential benefit of SWIR to NIR imaging in clinical samples containing cetuximab-IRDye800CW in fluorescence-guided surgery. APPROACH: The potential of the epidermal growth factor-targeted NIR dye cetuximab-IRDye800CW in the shortwave range was examined by recording the absorption and emission spectrum. An ex vivo comparison of NIR and SWIR images using clinical tumor samples of patients with penile squamous cell carcinoma (PSCC) and head and neck squamous cell carcinoma (HNSCC) containing cetuximab-IRDye800CW was performed. The comparison was based on the tumor-to-background ratio and an adapted contrast-to-noise ratio (aCNR) using the standard of care pathology tissue assessment as the golden standard. RESULTS: Based on the emission spectrum, cetuximab-IRDye800CW can be detected in the SWIR range. In clinical PSCC samples, overall SWIR imaging was found to perform similarly to NIR imaging (NIR imaging is better than SWIR in the 2/7 criteria examined, and SWIR is better than NIR in the 3/7 criteria). However, when inspecting HNSCC data, NIR is better than SWIR in nearly all (5/7) examined criteria. This difference seems to originate from background autofluorescence overwhelming the off-peak SWIR fluorescence signal in HNSCC tissue. CONCLUSION: SWIR imaging using the targeted tracer cetuximab-IRDye800CW currently does not provide additional benefit over NIR imaging in ex vivo clinical samples. Background fluorescence in the SWIR region, resulting in a higher background signal, limits SWIR imaging in HNSCC samples. However, SWIR shows potential in increasing the contrast of tumor borders in PSCC samples, as shown by a higher aCNR over a line. AU - Keizers, B.* AU - Nijboer, T.S.* AU - van der Fels, C.A.M.* AU - van den Heuvel, M.C.* AU - van Dam, G.M.* AU - Kruijff, S.* AU - Jan de Jong, I.* AU - Witjes, M.J.H.* AU - Voskuil, F.J.* AU - Gorpas, D. AU - Browne, W.R.* AU - van der Zaag, P.J.* C1 - 72393 C2 - 56568 TI - Systematic comparison of fluorescence imaging in the near-infrared and shortwave-infrared spectral range using clinical tumor samples containing cetuximab-IRDye800CW. JO - J. Biomed. Opt. VL - 30 IS - Suppl 1 PY - 2025 SN - 1083-3668 ER - TY - JOUR AB - SIGNIFICANCE: Standardization of fluorescence molecular imaging (FMI) is critical for ensuring quality control in guiding surgical procedures. To accurately evaluate system performance, two metrics, the signal-to-noise ratio (SNR) and contrast, are widely employed. However, there is currently no consensus on how these metrics can be computed. AIM: We aim to examine the impact of SNR and contrast definitions on the performance assessment of FMI systems. APPROACH: We quantified the SNR and contrast of six near-infrared FMI systems by imaging a multi-parametric phantom. Based on approaches commonly used in the literature, we quantified seven SNRs and four contrast values considering different background regions and/or formulas. Then, we calculated benchmarking (BM) scores and respective rank values for each system. RESULTS: We show that the performance assessment of an FMI system changes depending on the background locations and the applied quantification method. For a single system, the different metrics can vary up to ∼ 35    dB (SNR), ∼ 8.65    a . u . (contrast), and ∼ 0.67    a . u . (BM score). CONCLUSIONS: The definition of precise guidelines for FMI performance assessment is imperative to ensure successful clinical translation of the technology. Such guidelines can also enable quality control for the already clinically approved indocyanine green-based fluorescence image-guided surgery. AU - Kriukova, E. AU - LaRochelle, E.* AU - Pfefer, T.J.* AU - Kanniyappan, U.* AU - Gioux, S.* AU - Pogue, B.W.* AU - Ntziachristos, V. AU - Gorpas, D. C1 - 71252 C2 - 56025 TI - Impact of signal-to-noise ratio and contrast definition on the sensitivity assessment and benchmarking of fluorescence molecular imaging systems. JO - J. Biomed. Opt. VL - 30 IS - Suppl 1 PY - 2025 SN - 1083-3668 ER - TY - JOUR AB - SIGNIFICANCE: Diffuse optical modalities such as broadband near-infrared spectroscopy (bNIRS) and hyperspectral imaging (HSI) represent a promising alternative for low-cost, non-invasive, and fast monitoring of living tissue. Particularly, the possibility of extracting the molecular composition of the tissue from the optical spectra deems the spectroscopy techniques as a unique diagnostic tool. AIM: No established method exists to streamline the inference of the biochemical composition from the optical spectrum for real-time applications such as surgical monitoring. We analyze a machine learning technique for inference of changes in the molecular composition of brain tissue. APPROACH: We propose modifications to the existing learnable methodology based on the Beer-Lambert law. We evaluate the method's applicability to linear and nonlinear formulations of this physical law. The approach is tested on data obtained from the bNIRS- and HSI-based monitoring of brain tissue. RESULTS: The results demonstrate that the proposed method enables real-time molecular composition inference while maintaining the accuracy of traditional methods. Preliminary findings show that Beer-Lambert law-based spectral unmixing allows contrasting brain anatomy semantics such as the vessel tree and tumor area. CONCLUSION: We present a data-driven technique for inferring molecular composition change from diffuse spectroscopy of brain tissue, potentially enabling intra-operative monitoring. AU - Ezhov, I.* AU - Scibilia, K.* AU - Giannoni, L.* AU - Kofler, F. AU - Iliash, I.* AU - Hsieh, F.* AU - Shit, S.* AU - Caredda, C.* AU - Lange, F.* AU - Montcel, B.* AU - Tachtsidis, I.* AU - Rueckert, D.* C1 - 71833 C2 - 56436 CY - 1000 20th St, Po Box 10, Bellingham, Wa 98225 Usa TI - Learnable real-time inference of molecular composition from diffuse spectroscopy of brain tissue. JO - J. Biomed. Opt. VL - 29 IS - 9 PB - Spie-soc Photo-optical Instrumentation Engineers PY - 2024 SN - 1083-3668 ER - TY - JOUR AB - SIGNIFICANCE: Cerebrospinal fluid (CSF) rhinorrhea (leakage of brain fluid from the nose) can be difficult to identify and currently requires invasive procedures, such as intrathecal fluorescein, which requires a lumbar drain placement. Fluorescein is also known to have rare but significant side effects including seizures and death. As the number of endonasal skull base cases increases, the number of CSF leaks has also increased for which an alternative diagnostic method would be highly advantageous to patients. AIM: We aim to develop an instrument to identify CSF leaks based on water absorption in the shortwave infrared (SWIR) without the need of intrathecal contrast agents. This device needed to be adapted to the anatomy of the human nasal cavity while maintaining low weight and ergonomic characteristics of current surgical instruments. APPROACH: Absorption spectra of CSF and artificial CSF were obtained to characterize the absorption peaks that could be targeted with SWIR light. Different illumination systems were tested and refined prior to adapting them into a portable endoscope for testing in 3D-printed models and cadavers for feasibility. RESULTS: We identified CSF to have an identical absorption profile as water. In our testing, a narrowband laser source at 1480 nm proved superior to using a broad 1450 nm LED. Using a SWIR enabling endoscope set up, we tested the ability to detect artificial CSF in a cadaver model. CONCLUSIONS: An endoscopic system based on SWIR narrowband imaging can provide an alternative in the future to invasive methods of CSF leak detection. AU - Klein, T. AU - Yang, S.* AU - Tusty, M.A.* AU - Nayak, J.V.* AU - Chang, M.T.* AU - Bruns, O.T. AU - Bischof, T.S. AU - Valdez, T.A.* C1 - 67796 C2 - 54274 CY - 1000 20th St, Po Box 10, Bellingham, Wa 98225 Usa TI - Development of a shortwave infrared sinuscope for the detection of cerebrospinal fluid leaks. JO - J. Biomed. Opt. VL - 28 IS - 9 PB - Spie-soc Photo-optical Instrumentation Engineers PY - 2023 SN - 1083-3668 ER - TY - JOUR AB - SIGNIFICANCE: Intravascular near-infrared fluorescence (NIRF) imaging aims to improve the inspection of vascular pathology using fluorescent agents with specificity to vascular disease biomarkers. The method has been developed to operate in tandem with an anatomical modality, such as intravascular ultrasound (IVUS), and complements anatomical readings with pathophysiological contrast, enhancing the information obtained from the hybrid examination. AIM: However, attenuation of NIRF signals by blood challenges NIRF quantification. We propose a new method for attenuation correction in NIRF intravascular imaging based on a fluorophore-coated guidewire that is used as a reference for the fluorescence measurement and provides a real-time measurement of blood attenuation during the NIRF examination. APPROACH: We examine the performance of the method in a porcine coronary artery ex vivo and phantoms using a 3.2F NIRF-IVUS catheter. RESULTS: We demonstrate marked improvement over uncorrected signals of up to 4.5-fold and errors of < 11 % for target signals acquired at distances up to 1 mm from the catheter system employed. CONCLUSIONS: The method offers a potential means of improving the accuracy of intravascular NIRF imaging under in vivo conditions. AU - Rauschendorfer, P. AU - Wissmeyer, G.* AU - Jaffer, F.A. AU - Gorpas, D. AU - Ntziachristos, V. C1 - 67619 C2 - 53926 CY - 1000 20th St, Po Box 10, Bellingham, Wa 98225 Usa TI - Accounting for blood attenuation in intravascular near-infrared fluorescence-ultrasound imaging using a fluorophore-coated guidewire. JO - J. Biomed. Opt. VL - 28 IS - 4 PB - Spie-soc Photo-optical Instrumentation Engineers PY - 2023 SN - 1083-3668 ER - TY - JOUR AB - The editorial introduces the JBO Special Section on Tissue Phantoms to Advance Biomedical Optical Systems. AU - Gorpas, D. AU - Wabnitz, H.* AU - Pfefer, T.J.* C1 - 65520 C2 - 52713 TI - Special section guest editorial: Tissue phantoms to advance biomedical optical systems. JO - J. Biomed. Opt. VL - 27 IS - 7 PY - 2022 SN - 1083-3668 ER - TY - JOUR AB - SIGNIFICANCE: Quantitative optoacoustic imaging (QOAI) continues to be a challenge due to the influence of nonlinear optical fluence distribution, which distorts the optoacoustic image representation. Nonlinear optical fluence correction in OA imaging is highly ill-posed, leading to the inaccurate recovery of optical absorption maps. This work aims to recover the optical absorption maps using deep learning (DL) approach by correcting for the fluence effect. AIM: Different DL models were compared and investigated to enable optical absorption coefficient recovery at a particular wavelength in a nonhomogeneous foreground and background medium. APPROACH: Data-driven models were trained with two-dimensional (2D) Blood vessel and three-dimensional (3D) numerical breast phantom with highly heterogeneous/realistic structures to correct for the nonlinear optical fluence distribution. The trained DL models such as U-Net, Fully Dense (FD) U-Net, Y-Net, FD Y-Net, Deep residual U-Net (Deep ResU-Net), and generative adversarial network (GAN) were tested to evaluate the performance of optical absorption coefficient recovery (or fluence compensation) with in-silico and in-vivo datasets. RESULTS: The results indicated that FD U-Net-based deconvolution improves by about 10% over reconstructed optoacoustic images in terms of peak-signal-to-noise ratio. Further, it was observed that DL models can indeed highlight deep-seated structures with higher contrast due to fluence compensation. Importantly, the DL models were found to be about 17 times faster than solving diffusion equation for fluence correction. CONCLUSIONS: The DL methods were able to compensate for nonlinear optical fluence distribution more effectively and improve the optoacoustic image quality. AU - Madasamy, A.* AU - Gujrati, V. AU - Ntziachristos, V. AU - Prakash, J.* C1 - 66336 C2 - 53139 TI - Deep learning methods hold promise for light fluence compensation in three-dimensional optoacoustic imaging. JO - J. Biomed. Opt. VL - 27 IS - 10 PY - 2022 SN - 1083-3668 ER - TY - JOUR AB - SIGNIFICANCE: Near-infrared fluorescence molecular endoscopy (NIR-FME) is an innovative technique allowing for in vivo visualization of molecular processes in hollow organs. Despite its potential for clinical translation, NIR-FME still faces challenges, for example, the lack of consensus in performing quality control and standardization of procedures and systems. This may hamper the clinical approval of the technology by authorities and its acceptance by endoscopists. Until now, several clinical trials using NIR-FME have been performed. However, most of these trials had different study designs, making comparison difficult. AIM: We describe the need for standardization in NIR-FME, provide a pathway for setting up a standardized clinical study, and describe future perspectives for NIR-FME. Body: Standardization is challenging due to many parameters. Invariable parameters refer to the hardware specifications. Variable parameters refer to movement or tissue optical properties. Phantoms can be of aid when defining the influence of these variables or when standardizing a procedure. CONCLUSION: There is a need for standardization in NIR-FME and hurdles still need to be overcome before a widespread clinical implementation of NIR-FME can be realized. When these hurdles are overcome, clinical outcomes can be compared and systems can be benchmarked, enabling clinical implementation. AU - Sterkenburg, A.J.* AU - Hooghiemstra, W.T.R.* AU - Schmidt, I.* AU - Ntziachristos, V. AU - Nagengast, W.B.* AU - Gorpas, D. C1 - 64360 C2 - 52213 TI - Standardization and implementation of fluorescence molecular endoscopy in the clinic. JO - J. Biomed. Opt. VL - 27 IS - 7 PY - 2022 SN - 1083-3668 ER - TY - JOUR AB - SIGNIFICANCE: Expanded use of fluorescence-guided surgery with devices approved for use with indocyanine green (ICG) has led to a range of commercial systems available. There is a compelling need to be able to independently characterize system performance and allow for cross-system comparisons. AIM: The goal of this work is to expand on previous proposed fluorescence imaging standard designs to develop a long-term stable phantom that spectrally matches ICG characteristics and utilizes 3D printing technology for incorporating tissue-equivalent materials. APPROACH: A batch of test targets was created to assess ICG concentration sensitivity in the 0.3- to 1000-nM range, tissue-equivalent depth sensitivity down to 6 mm, and spatial resolution with a USAF test chart. Comparisons were completed with a range of systems that have significantly different imaging capabilities and applications, including the Li-Cor® Odyssey, Li-Cor® Pearl, PerkinElmer® Solaris, and Stryker® Spy Elite. RESULTS: Imaging of the ICG-matching phantoms with all four commercially available systems showed the ability to benchmark system performance and allow for cross-system comparisons. The fluorescence tests were able to assess differences in the detectable concentrations of ICG with sensitivity differences >10× for preclinical and clinical systems. Furthermore, the tests successfully assessed system differences in the depth-signal decay rate, as well as resolution performance and image artifacts. The manufacturing variations, photostability, and mechanical design of the tests showed promise in providing long-term stable standards for fluorescence imaging. CONCLUSIONS: The presented ICG-matching phantom provides a major step toward standardizing performance characterization and cross-system comparisons for devices approved for use with ICG. The developed hybrid manufacturing platform can incorporate long-term stable fluorescing agents with 3D printed tissue-equivalent material. Further, long-term testing of the phantom and refinements to the manufacturing process are necessary for future implementation as a widely adopted fluorescence imaging standard. AU - Ruiz, A.J.* AU - Wu, M.* AU - LaRochelle, E.P.M.* AU - Gorpas, D. AU - Ntziachristos, V. AU - Pfefer, T.J.* AU - Pogue, B.W.* C1 - 59190 C2 - 48654 SP - 1-15 TI - Indocyanine green matching phantom for fluorescence-guided surgery imaging system characterization and performance assessment. JO - J. Biomed. Opt. VL - 25 IS - 5 PY - 2020 SN - 1083-3668 ER - TY - JOUR AB - Fluorescence molecular imaging (FMI) has shown potential to detect and delineate cancer during surgery or diagnostic endoscopy. Recent progress on imaging systems has allowed sensitive detection of fluorescent agents even in video rate mode. However, lack of standardization in fluorescence imaging challenges the clinical application of FMI, since the use of different systems may lead to different results from a given study, even when using the same fluorescent agent. In this work, we investigate the use of a composite fluorescence phantom, employed as an FMI standard, to offer a comprehensive method for validation and standardization of the performance of different imaging systems. To exclude user interaction, all phantom features are automatically extracted from the acquired epi-illumination color and fluorescence images, using appropriately constructed templates. These features are then employed to characterize the performance and compare different cameras to each other. The proposed method could serve as a framework toward the calibration and benchmarking of FMI systems, to facilitate their clinical translation. AU - Gorpas, D. AU - Koch, M. AU - Anastasopoulou, M. AU - Klemm, U. AU - Ntziachristos, V. C1 - 50341 C2 - 42112 TI - Benchmarking of fluorescence cameras through the use of a composite phantom. JO - J. Biomed. Opt. VL - 22 IS - 1 PY - 2017 SN - 1083-3668 ER - TY - JOUR AB - Frequency characteristics of ultrasound detectors used in optoacoustic tomography have a major impact on imaging performance. It is common practice to select transducers based on their sensitivity at the central frequency and under normal incidence. However, the bandwidth and angular sensitivity play an equally important role in establishing the quality and accuracy of the reconstructed images. Here, we developed a calibrated optoacoustic characterization method specifically tailored for broadband measurements of the angular transducer sensitivity (directivity). Ultrawideband omnidirectional optoacoustic responses were generated by uniformly illuminating thin absorbing sutures with nanosecond laser pulses and characterized with a needle hydrophone. This calibrated optoacoustic source was used to characterize the frequency dependence of the angular response by a conventional piezoelectric transducer (PZT) and a capacitive micromachined ultrasonic transducer (cMUT) with similar size and central frequency. Furthermore, both transducers had no preamplification electronics directly attached to the detection elements. While the PZT presented a 7.8 dB sensitivity advantage at normal incidence, it was able to provide detectable signal-to-noise levels only at incidence angles of up to 20 deg whereas the cMUT maintained reasonable sensitivity levels and broadband response at incidence angles of 40 deg and beyond. We further experimentally showcase a reduction in the limited-view image artifacts resulting from the broader acceptance angle of the cMUT. AU - Rebling, J. AU - Warshavski, O.* AU - Meynier, C.* AU - Razansky, D. C1 - 49929 C2 - 41904 CY - Bellingham TI - Optoacoustic characterization of broadband directivity patterns of capacitive micromachined ultrasonic transducers. JO - J. Biomed. Opt. VL - 22 IS - 4 PB - Spie-soc Photo-optical Instrumentation Engineers PY - 2017 SN - 1083-3668 ER - TY - JOUR AB - Fluorescence imaging has been considered for over a half-century as a modality that could assist surgical guidance and visualization. The administration of fluorescent molecules with sensitivity to disease biomarkers and their imaging using a fluorescence camera can outline pathophysiological parameters of tissue invisible to the human eye during operation. The advent of fluorescent agents that target specific cellular responses and molecular pathways of disease has facilitated the intraoperative identification of cancer with improved sensitivity and specificity over nonspecific fluorescent dyes that only outline the vascular system and enhanced permeability effects. With these new abilities come unique requirements for developing phantoms to calibrate imaging systems and algorithms. We briefly review herein progress with fluorescence phantoms employed to validate fluorescence imaging systems and results. We identify current limitations and discuss the level of phantom complexity that may be required for developing a universal strategy for fluorescence imaging calibration. Finally, we present a phantom design that could be used as a tool for interlaboratory system performance evaluation. AU - Anastasopoulou, M. AU - Koch, M. AU - Gorpas, D. AU - Karlas, A. AU - Klemm, U. AU - Garcia-Allende, P. AU - Ntziachristos, V. C1 - 48823 C2 - 41486 CY - Bellingham TI - Comprehensive phantom for interventional fluorescence molecular imaging. JO - J. Biomed. Opt. VL - 21 IS - 9 PB - Spie-soc Photo-optical Instrumentation Engineers PY - 2016 SN - 1083-3668 ER - TY - JOUR AB - In optoacoustic tomography, detectors with relatively large areas are often employed to achieve high detection sensitivity. However, spatial-averaging effects over large detector areas may lead to attenuation of high acoustic frequencies and, subsequently, loss of fine features in the reconstructed image. Model-based reconstruction algorithms improve image resolution in such cases by correcting for the effect of the detector's aperture on the detected signals. However, the incorporation of the detector's geometry in the optoacoustic model leads to a significant increase of the model matrix memory cost, which hinders the application of inversion and analysis tools such as singular value decomposition (SVD). We demonstrate the use of the wavelet-packet framework for optoacoustic systems with finite-aperture detectors. The decomposition of the model matrix in the wavelet-packet domain leads to sufficiently smaller model matrices on which SVD may be applied. Using this methodology over an order of magnitude reduction in inversion time is demonstrated for numerically generated and experimental data. Additionally, our framework is demonstrated for the analysis of inversion stability and reveals a new, nonmonotonic dependency of the system condition number on the detector size. Thus, the proposed framework may assist in choosing the optimal detector size in future optoacoustic systems. AU - Han, Y. AU - Ntziachristos, V. AU - Rosenthal, A. C1 - 47663 C2 - 39463 CY - Bellingham TI - Optoacoustic image reconstruction and system analysis for finite-aperture detectors under the wavelet-packet framework. JO - J. Biomed. Opt. VL - 21 IS - 1 PB - Spie-soc Photo-optical Instrumentation Engineers PY - 2016 SN - 1083-3668 ER - TY - JOUR AB - cattering within biological samples limits the imaging depth and the resolution in microscopy. We present a prior and regularization approach for blind deconvolution algorithms to correct the influence of scattering to increase the imaging depth and resolution. The effect of the prior is demonstrated on a three-dimensional image stack of a zebrafish embryo captured with a selective plane illumination microscope. Blind deconvolution algorithms model the recorded image as a convolution between the distribution of fluorophores and a point spread function (PSF). Our prior uses image information from adjacent z-planes to estimate the unknown blur in tissue. The increased size of the PSF due to the cascading effect of scattering in deeper tissue is accounted for by a depth adaptive regularizer model. In a zebrafish sample, we were able to extend the point in depth, where scattering has a significant effect on the image quality by around 30  μm. AU - Koberstein-Schwarz, B. AU - Omlor, L.* AU - Schmitt-Manderbach, T.* AU - Mappes, T.* AU - Ntziachristos, V. C1 - 49465 C2 - 31241 CY - Bellingham TI - Scattering correction through a space-variant blind deconvolution algorithm. JO - J. Biomed. Opt. VL - 21 IS - 9 PB - Spie-soc Photo-optical Instrumentation Engineers PY - 2016 SN - 1083-3668 ER - TY - JOUR AB - Nuclear imaging plays a critical role in asthma research but is limited in its readings of biology due to the short-lived signals of radio-isotopes. We employed hybrid fluorescence molecular tomography (FMT) and x-ray computed tomography (XCT) for the assessment of asthmatic inflammation based on resolving cathepsin activity and matrix metalloproteinase activity in dust mite, ragweed, and Aspergillus species-challenged mice. The reconstructed multimodal fluorescence distribution showed good correspondence with ex vivo cryosection images and histological images, confirming FMT-XCT as an interesting alternative for asthma research. AU - Ma, X. AU - Prakash, J. AU - Ruscitti, F.* AU - Glasl, S. AU - Stellari, F.F.* AU - Villetti, G.* AU - Ntziachristos, V. C1 - 47751 C2 - 39458 CY - Bellingham TI - Assessment of asthmatic inflammation using hybrid fluorescence molecular tomography-X-ray computed tomography. JO - J. Biomed. Opt. VL - 21 IS - 1 PB - Spie-soc Photo-optical Instrumentation Engineers PY - 2016 SN - 1083-3668 ER - TY - JOUR AB - Expanding usage of small animal models in biomedical research necessitates development of technologies for structural, functional, or molecular imaging that can be readily integrated in the biological laboratory. Herein, we consider dual multispectral optoacoustic (OA) and ultrasound tomography based on curved ultrasound detector arrays and describe the performance achieved for hybrid morphological and physiological brain imaging of mice in vivo. We showcase coregistered hemodynamic parameters resolved by OA tomography under baseline conditions and during alterations of blood oxygen saturation. As an internal reference, we provide imaging of abdominal organs. We illustrate the performance advantages of hybrid curved detector ultrasound and OA tomography and discuss immediate and long-term implications of our findings in the context of animal and human studies. AU - Olefir, I. AU - Mercep, E. AU - Burton, N.C.* AU - Ovsepian, S.V. AU - Ntziachristos, V. C1 - 49276 C2 - 41732 CY - Bellingham TI - Hybrid multispectral optoacoustic and ultrasound tomography for morphological and physiological brain imaging. JO - J. Biomed. Opt. VL - 21 IS - 8 PB - Spie-soc Photo-optical Instrumentation Engineers PY - 2016 SN - 1083-3668 ER - TY - JOUR AB - © 2015 Society of Photo-Optical Instrumentation Engineers (SPIE). Reconstructing a three-dimensional scene from multiple simultaneously acquired perspectives (the light field) is an elegant scanless imaging concept that can exceed the temporal resolution of currently available scanning-based imaging methods for capturing fast cellular processes. We tested the performance of commercially available light field cameras on a fluorescent microscopy setup for monitoring calcium activity in the brain of awake and behaving reporter zebrafish larvae. The plenoptic imaging system could volumetrically resolve diverse neuronal response profiles throughout the zebrafish brain upon stimulation with an aversive odorant. Behavioral responses of the reporter fish could be captured simultaneously together with depth-resolved neuronal activity. Overall, our assessment showed that with some optimizations for fluorescence microscopy applications, commercial light field cameras have the potential of becoming an attractive alternative to custom-built systems to accelerate molecular imaging research on cellular dynamics. AU - Cruz Perez, C. AU - Lauri, A. AU - Symvoulidis, P. AU - Cappetta, M. AU - Erdmann, A.* AU - Westmeyer, G.G. C1 - 46789 C2 - 37813 TI - Calcium neuroimaging in behaving zebrafish larvae using a turn-key light field camera. JO - J. Biomed. Opt. VL - 20 IS - 9 PY - 2015 SN - 1083-3668 ER - TY - JOUR AB - ABSTRACT. Optoacoustic (photoacoustic) imaging has already showcased the capacity to offer high-resolution small animal visualization in vivo in a variety of cancer, cardiovascular, or neuroimaging applications. In particular, multispectral optoacoustic tomography (MSOT) has shown imaging along the spectral and the time dimensions, enabling sensing of multiple molecules over time and, more recently, in real time. Furthermore, cross-sectional imaging of at least 20 mm diameter has been showcased in vivo in animals and humans using 64-element curved transducers placed along a single curved line. Herein, we investigated the imaging improvements gained by utilizing a larger number of detectors and inquired whether more detectors will result in measurable image quality improvements. For this reason, we implemented MSOT using 64-, 128-, and 256-element transducers and imaged the same phantoms and animals under similar conditions. Further, corroborated by numerical simulation analysis, our findings quantify the improvements in resolution and overall image quality for the increasing number of detectors used pointing to significant improvements in image quality for the 256 detector array, over 64 or 128 detectors. AU - Dima, A. AU - Burton, N.C.* AU - Ntziachristos, V. C1 - 30918 C2 - 34021 CY - Bellingham TI - Multispectral optoacoustic tomography at 64, 128, and 256 channels. JO - J. Biomed. Opt. VL - 19 IS - 3 PB - Spie-soc Photo-optical Instrumentation Engineers PY - 2014 SN - 1083-3668 ER - TY - JOUR AB - ABSTRACT. Molecular fluorescence imaging is a commonly used method in various biomedical fields and is undergoing rapid translation toward clinical applications. Color images are commonly superimposed with fluorescence measurements to provide orientation, anatomical information, and molecular tissue properties in a single image. New adaptive methods that produce a more robust composite image than conventional lime green alpha blending are presented and demonstrated herein. Moreover, visualization through temporal changes is showcased as an alternative for real-time imaging systems. AU - Glatz, J.* AU - Symvoulidis, P. AU - Garcia-Allende, P.* AU - Ntziachristos, V. C1 - 30999 C2 - 34077 CY - Bellingham TI - Robust overlay schemes for the fusion of fluorescence and color channels in biological imaging. JO - J. Biomed. Opt. VL - 19 IS - 4 PB - Spie-soc Photo-optical Instrumentation Engineers PY - 2014 SN - 1083-3668 ER - TY - JOUR AB - ABSTRACT. Intraoperative fluorescence molecular imaging based on targeted fluorescence agents is an emerging approach to improve surgical and endoscopic imaging and guidance. Short exposure times per frame and implementation at video rates are necessary to provide continuous feedback to the physician and avoid motion artifacts. However, fast imaging implementations also limit the sensitivity of fluorescence detection. To improve on detection sensitivity in video rate fluorescence imaging, we considered herein an optical flow technique applied to texture-rich color images. This allows the effective accumulation of fluorescence signals over longer, virtual exposure times. The proposed correction scheme is shown to improve signal-to-noise ratios both in phantom experiments and in vivo tissue imaging. AU - Koch, M. AU - Glatz, J. AU - Ermolayev, V. AU - de Vries, E.G.* AU - van Dam, G.M.* AU - Englmeier, K.-H. AU - Ntziachristos, V. C1 - 31099 C2 - 34126 CY - Bellingham TI - Video-rate optical flow corrected intraoperative functional fluorescence imaging. JO - J. Biomed. Opt. VL - 19 IS - 4 PB - Spie-soc Photo-optical Instrumentation Engineers PY - 2014 SN - 1083-3668 ER - TY - JOUR AB - ABSTRACT. An advantage of fluorescence methods over other imaging modalities is the ability to concurrently resolve multiple moieties using fluorochromes emitting at different spectral regions. Simultaneous imaging of spectrally separated agents is helpful in interrogating multiple functions or establishing internal controls for accurate measurements. Herein, we investigated multimoiety imaging in the context of a limited-projection-angle hybrid fluorescence molecular tomography (FMT), and x-ray computed tomography implementation and the further registration with positron emission tomography (PET) data. Multichannel FMT systems may image fluorescent probes of varying distribution patterns. Therefore, it is possible that different channels may require different use of priors and regularization parameters. We examined the performance of automatically estimating regularization factors implementing priors, using data-driven regularization specific for limited-projection-angle schemes. We were particularly interested in identifying the implementation variations between hybrid-FMT channels due to probe distribution variation. For this reason, initial validation of the data-driven algorithm on a phantom was followed by imaging different agent distributions in animals, assuming superficial and deep seated activity. We further demonstrate the benefits of combining hybrid FMT with PET to gain multiple readings on the molecular composition of disease. AU - Radrich, K. AU - Mohajerani, P. AU - Bussemer, J.* AU - Schwaiger, M.* AU - Beer, A.J.* AU - Ntziachristos, V. C1 - 31139 C2 - 34163 CY - Bellingham TI - Limited-projection-angle hybrid fluorescence molecular tomography of multiple molecules. JO - J. Biomed. Opt. VL - 19 IS - 4 PB - Spie-soc Photo-optical Instrumentation Engineers PY - 2014 SN - 1083-3668 ER - TY - JOUR AB - ABSTRACT. The ability to visualize early stage lung cancer is important in the study of biomarkers and targeting agents that could lead to earlier diagnosis. The recent development of hybrid free-space 360-deg fluorescence molecular tomography (FMT) and x-ray computed tomography (XCT) imaging yields a superior optical imaging modality for three-dimensional small animal fluorescence imaging over stand-alone optical systems. Imaging accuracy was improved by using XCT information in the fluorescence reconstruction method. Despite this progress, the detection sensitivity of targeted fluorescence agents remains limited by nonspecific background accumulation of the fluorochrome employed, which complicates early detection of murine cancers. Therefore we examine whether x-ray CT information and bulk fluorescence detection can be combined to increase detection sensitivity. Correspondingly, we research the performance of a data-driven fluorescence background estimator employed for subtraction of background fluorescence from acquisition data. Using mice containing known fluorochromes ex vivo, we demonstrate the reduction of background signals from reconstructed images and sensitivity improvements. Finally, by applying the method to in vivo data from K-ras transgenic mice developing lung cancer, we find small tumors at an early stage compared with reconstructions performed using raw data. We conclude with the benefits of employing fluorescence subtraction in hybrid FMT-XCT for early detection studies. AU - Ale, A.B.F AU - Ermolayev, V. AU - Deliolanis, N.C. AU - Ntziachristos, V. C1 - 24358 C2 - 31509 TI - Fluorescence background subtraction technique for hybrid fluorescence molecular tomography/X-ray computed tomography imaging of a mouse model of early stage lung cancer. JO - J. Biomed. Opt. VL - 18 IS - 5 PB - SPIE PY - 2013 SN - 1083-3668 ER - TY - JOUR AB - ABSTRACT. Current fluorescence diffuse optical tomography (fDOT) systems can provide large data sets and, in addition, the unknown parameters to be estimated are so numerous that the sensitivity matrix is too large to store. Alternatively, iterative methods can be used, but they can be extremely slow at converging when dealing with large matrices. A few approaches suitable for the reconstruction of images from very large data sets have been developed. However, they either require explicit construction of the sensitivity matrix, suffer from slow computation times, or can only be applied to restricted geometries. We introduce a method for fast reconstruction in fDOT with large data and solution spaces, which preserves the resolution of the forward operator whilst compressing its representation. The method does not require construction of the full matrix, and thus allows storage and direct inversion of the explicitly constructed compressed system matrix. The method is tested using simulated and experimental data. Results show that the fDOT image reconstruction problem can be effectively compressed without significant loss of information and with the added advantage of reducing image noise. AU - Correia, T.* AU - Rudge, T.* AU - Koch, M. AU - Ntziachristos, V. AU - Arridge, S.* C1 - 26893 C2 - 32439 TI - Wavelet-based data and solution compression for efficient image reconstruction in fluorescence diffuse optical tomography. JO - J. Biomed. Opt. VL - 18 IS - 8 PB - SPIE PY - 2013 SN - 1083-3668 ER - TY - JOUR AB - Optoacoustic (photoacoustic) mesoscopy aims at high-resolution optical imaging of anatomical, functional, and cellular parameters at depths that go well beyond those of optical-resolution optical or optoacoustic microscopy i.e., reaching several millimeters in depth. The approach utilizes tomography to achieve ultrasonic-diffraction resolution and operates at high-ultrasound frequencies (20 to 200 MHz) induced by few-nanosecond laser pulse excitation of tissues. We investigated here the performance of optoacoustic mesoscopy implemented at 24 MHz center frequency and its ability to resolve optical absorption contrast in the mouse kidney ex vivo. The developed system achieved better than 30 μm in-plane resolution and 110 μm elevation resolution over a cylindrical volume of 9-mm diameter and 9-mm height. This unprecedented combination of resolution and depth was achieved by implementing a translate-rotate detection geometry and by tomographic reconstruction. The approach yielded images of optically absorbing structures with a level of detail never-before visualized in an intact mouse kidney and allows insights into their unperturbed architecture. We discuss the ability to offer multispectral acquisitions and enable in vivo imaging. AU - Gateau, J. AU - Chekkoury, A. AU - Ntziachristos, V. C1 - 27769 C2 - 32805 TI - High-resolution optoacoustic mesoscopy with a 24 MHz multidetector translate-rotate scanner. JO - J. Biomed. Opt. VL - 18 IS - 10 PB - SPIE PY - 2013 SN - 1083-3668 ER - TY - JOUR AB - The visual identification and demarcation of tumors and tumor margins remains challenging due to the low optical contrast of cancer cells over surrounding tissues. Fluorescence molecular imaging was recently considered clinically for improving cancer detection during open surgery. We present herein a next step in the development of fluorescence molecular guidance by describing a novel video-rate imaging laparoscope capable of concurrently recording color and near-infrared fluorescence images and video. Video-rate operation is based on graphics processing unit-based image processing. We examine the optical characteristics of the system developed and provide performance metrics related to intra-operative endoscopic guidance, showcased on phantoms and endoscopic color and fluorescence molecular imaging of tumors in a mouse model of the human disease. AU - Glatz, J.* AU - Varga, J.* AU - Garcia-Allende, P. AU - Koch, M. AU - Greten, F.R.* AU - Ntziachristos, V. C1 - 24790 C2 - 31680 TI - Concurrent video-rate color and near-infrared fluorescence laparoscopy. JO - J. Biomed. Opt. VL - 18 IS - 10 PB - SPIE PY - 2013 SN - 1083-3668 ER - TY - JOUR AB - ABSTRACT. Rheumatoid arthritis (RA) is the most common chronic inflammatory joint disease, with a prevalence of 0.5 to 1% in the general population. Imaging can possibly aid in early diagnosis, crucial to effective personalized therapeutic strategies and treatment follow-up. The intravenous administration of indocyanine green (ICG) has been considered for identifying synovial hyperperfusion as an RA physiological biomarker. However, while the distribution of ICG in the human hand is a time-dependent process, the particular biodistribution dynamic patterns established following intravenous administration have not yet been studied. For this reason, the dynamic relationships of ICG distribution in the human hand in RA patients using a method based on principal component analysis are analyzed. In vivo analyses were corroborated by simulations of clinical scenarios using a finite element method. Observations of spatiotemporal characteristics are contrasted to fluorescence intensity images and magnetic resonance images of the hand joints, employed as the anatomical and diagnostic reference. Processing results for 450 joints from 5 healthy volunteers and 10 patients show that image features obtained from the spatiotemporal analysis offer good congruence with synovitis and reveal better detection performance compared to observations of raw fluorescence intensity images. AU - Mohajerani, P. AU - Meier, R.* AU - Noel, P.B.* AU - Rummeny, E.J.* AU - Ntziachristos, V. C1 - 27662 C2 - 32791 TI - Spatiotemporal analysis for indocyanine green-aided imaging of rheumatoid arthritis in hand joints. JO - J. Biomed. Opt. VL - 18 IS - 9 PB - SPIE PY - 2013 SN - 1083-3668 ER - TY - JOUR AB - Professor Roger Y. Tsien is a renowned world leader in chemical biology and biochemistry whose pioneering work in fluorescence sensing and imaging has revolutionized virtually all of experimental biology. He is an insightful scientist, and a cordial colleague and mentor; always invigorating with his ideas and energy, and inspiring with his vision. There are 18 contributions in this special section, covering the topics of developing infrared fluorescence microscopy, fluorescent dyes, and probes. The application of these tools and probes also indicates their broad impact, with the model systems of their applications ranging from tumors and cancers to cardiomyocytes and cardiovascular systems. To date, Prof. Tsien continues to lead and contribute to the emerging fields of molecular and cellular imaging as well as biomedical optics. AU - Ntziachristos, V. AU - Achilefu, S.* AU - Wang, Y.P.* AU - Lin, M.* C1 - 28489 C2 - 33423 TI - Special section on fluorescence molecular imaging honoring Prof. Roger Tsien, a pioneer in biomedical optics. JO - J. Biomed. Opt. VL - 18 IS - 10 PB - SPIE PY - 2013 SN - 1083-3668 ER - TY - JOUR AB - ABSTRACT. Cross sectional tomographic systems based on cylindrically focused transducers are widely used in optoacoustic (photoacoustic) imaging due to important advantages they provide such as high-cross sectional resolution, real-time imaging capacity, and high-throughput performance. Tomographic images in such systems are commonly obtained by means of two-dimensional (2-D) reconstruction procedures assuming point-like detectors, and volumetric (whole-body) imaging is performed by superimposing the cross sectional images for different positions along the scanning direction. Such reconstruction strategy generally leads to in-plane and out-of-plane artifacts as well as significant quantification errors. Herein, we introduce two equivalent full three-dimensional (3-D) models capable of accounting for the shape of cylindrically focused transducers. The performance of these models in 3-D reconstructions considering several scanning positions is analyzed in this work. Improvements of the results rendered with the introduced reconstruction procedure as compared with the 2-D-based approach are described and discussed for simulations and experiments with phantoms and biological tissues. AU - Queirós, D. AU - Dean-Ben, X.L. AU - Bühler, A. AU - Razansky, D. AU - Rosenthal, A. AU - Ntziachristos, V. C1 - 26011 C2 - 32021 TI - Modeling the shape of cylindrically focused transducers in three-dimensional optoacoustic tomography. JO - J. Biomed. Opt. VL - 18 IS - 7 PB - SPIE PY - 2013 SN - 1083-3668 ER - TY - JOUR AB - ABSTRACT. The quality of optoacoustic tomographic reconstructions can be severely affected by acoustic reflections or scattering arising at interfaces of highly mismatched organs, such as bones, lungs, or other air-containing cavities. We present a procedure to reduce the associated artefacts based on estimation of the acoustic scatterers distribution within the imaged object. Signals generated by a strong optical absorber are processed and used in a weighted back-projection algorithm. Experimental results in a tissue-mimicking phantom clearly demonstrate improved performance as compared to the case in which no information on the distribution of acoustic scatterers is available. AU - Dean-Ben, X.L. AU - Ntziachristos, V. AU - Razansky, D. C1 - 10960 C2 - 30450 TI - Artefact reduction in optoacoustic tomographic imaging by estimating the distribution of acoustic scatterers. JO - J. Biomed. Opt. VL - 17 IS - 11 PB - SPIE PY - 2012 SN - 1083-3668 ER - TY - JOUR AB - We examine the improvement in imaging performance, such as axial resolution and signal localization, when employing limited-projection-angle fluorescence molecular tomography (FMT) together with x-ray computed tomography (XCT) measurements versus stand-alone FMT. For this purpose, we employed living mice, bearing a spontaneous lung tumor model, and imaged them with FMT and XCT under identical geometrical conditions using fluorescent probes for cancer targeting. The XCT data was employed, herein, as structural prior information to guide the FMT reconstruction. Gold standard images were provided by fluorescence images of mouse cryoslices, providing the ground truth in fluorescence bio-distribution. Upon comparison of FMT images versus images reconstructed using hybrid FMT and XCT data, we demonstrate marked improvements in image accuracy. This work relates to currently disseminated FMT systems, using limited projection scans, and can be employed to enhance their performance. AU - Radrich, K. AU - Ale, A.B.F AU - Ermolayev, V. AU - Ntziachristos, V. C1 - 11424 C2 - 30660 TI - Improving limited-projection-angle fluorescence molecular tomography using a co-registered X-ray computed tomography scan. JO - J. Biomed. Opt. VL - 17 IS - 12 PB - SPIE - Society of Photo-optical Instrumentation Engineers PY - 2012 SN - 1083-3668 ER - TY - JOUR AB - Cardiac imaging in small animals is a valuable tool in basic biological research and drug discovery for cardiovascular disease. Multispectral optoacoustic tomography (MSOT) represents an emerging imaging modality capable of visualizing specific tissue chromophores at high resolution and deep in tissues in vivo by separating their spectral signatures. Whereas single-wavelength images can be acquired by multielement ultrasound detection in real-time imaging, using multiple wavelengths at separate times can lead to image blurring due to motion during acquisition. Therefore, MSOT imaging of the heart results in degraded resolution because of the heartbeat. In this work, we applied a clustering algorithm, k-means, to automatically separate a sequence of single-pulse images at multiple excitation wavelengths into clusters corresponding to different stages of the cardiac cycle. We then performed spectral unmixing on each cluster to obtain images of tissue intrinsic chromophores at different cardiac stages, showing reduced sensitivity to motion compared to signal averaging without clustering. We found that myocardium images of improved resolution and contrast can be achieved using MSOT motion clustering correction. The correction method presented could be generally applied to other MSOT imaging applications prone to motion artifacts, for example, by respiration and heartbeat. AU - Taruttis, A. AU - Claussen, J. AU - Razansky, D. AU - Ntziachristos, V. C1 - 7200 C2 - 29545 TI - Motion clustering for deblurring multispectral optoacoustic tomography images of the mouse heart. JO - J. Biomed. Opt. VL - 17 IS - 1 PB - Society of Photo-Optical Instrumentation Engineers PY - 2012 SN - 1083-3668 ER - TY - JOUR AB - Mesoscopic epifluorescence tomography is a novel technique that discovers fluorescence bio-distribution in small animals by tomographic means in reflectance geometry. A collimated laser beam is scanned over the skin surface to excite fluorophores hidden within the tissue while a CCD camera acquires an image of the fluorescence emission for each source position. This configuration is highly efficient in the visible spectrum range where trans-illumination imaging of small animals is not feasible due to the high tissue absorption and scattering in biological organisms. The reconstruction algorithm is similar to the one used in fluorescence molecular tomography. However, diffusion theory cannot be employed since the source-detector separation for most image pixels is comparable to or below the scattering length of the tissue. Instead Monte Carlo simulations are utilized to predict the sensitivity functions. In a phantom study we show the effect of using enhanced source grid arrangements during the data acquisition and the reconstruction process to minimize boundary artefacts. Furthermore, we present ex vivo data that show high spatial resolution and quantitative accuracy in heterogeneous tissues using GFP-like fluorescence in B6-albino mice up to a depth of 1100 μm. AU - Björn, S. AU - Englmeier, K.-H. AU - Ntziachristos, V. AU - Schulz, R.B. C1 - 6298 C2 - 28325 CY - Bellingham, WA TI - Reconstruction of fluorescence distribution hidden in biological tissue using mesoscopic epifluorescence tomography. JO - J. Biomed. Opt. VL - 16 IS - 4 PB - SPIE PY - 2011 SN - 1083-3668 ER - TY - JOUR AB - Mesoscopic epifluorescence tomography is a novel technique that discovers fluorescence bio-distribution in small animals by tomographic means in reflectance geometry. A collimated laser beam is scanned over the skin surface to excite fluorophores hidden within the tissue while a CCD camera acquires an image of the fluorescence emission for each source position. This configuration is highly efficient in the visible spectrum range where trans-illumination imaging of small animals is not feasible due to the high tissue absorption and scattering in biological organisms. The reconstruction algorithm is similar to the one used in fluorescence molecular tomography. However, diffusion theory cannot be employed since the source-detector separation for most image pixels is comparable to or below the scattering length of the tissue. Instead Monte Carlo simulations are utilized to predict the sensitivity functions. In a phantom study we show the effect of using enhanced source grid arrangements during the data acquisition and the reconstruction process to minimize boundary artefacts. Furthermore, we present ex vivo data that show high spatial resolution and quantitative accuracy in heterogeneous tissues using GFP-like fluorescence in B6-albino mice up to a depth of 1100 μm. AU - Björn, S. AU - Englmeier, K.-H. AU - Ntziachristos, V. AU - Schulz, R. C1 - 30978 C2 - 34055 TI - Reconstruction of fluorescence distribution hidden in biological tissue using mesoscopic epifluorescence tomography. JO - J. Biomed. Opt. VL - 16 IS - 4 PY - 2010 SN - 1083-3668 ER - TY - JOUR AB - New imaging methods are urgently needed to identify high-risk atherosclerotic lesions prior to the onset of myocardial infarction, stroke, and ischemic limbs. Molecular imaging offers a new approach to visualize key biological features that characterize high-risk plaques associated with cardiovascular events. While substantial progress has been realized in clinical molecular imaging of plaques in larger arterial vessels (carotid, aorta, iliac), there remains a compelling, unmet need to develop molecular imaging strategies targeted to high-risk plaques in human coronary arteries. We present recent developments in intravascular near-IR fluorescence catheter-based strategies for in vivo detection of plaque inflammation in coronary-sized arteries. In particular, the biological, light transmission, imaging agent, and engineering principles that underlie a new intravascular near-IR fluorescence sensing method are discussed. Intravascular near-IR fluorescence catheters appear highly translatable to the cardiac catheterization laboratory, and thus may offer a new in vivo method to detect high-risk coronary plaques and to assess novel atherosclerosis biologics. AU - Calfon, M.A.* AU - Vinegoni, C.* AU - Ntziachristos, V. AU - Jaffer, F.A.* C1 - 99 C2 - 27187 TI - Intravascular near-infrared fluorescence molecular imaging of atherosclerosis: Toward coronary arterial visualization of biologically high-risk plaques. JO - J. Biomed. Opt. VL - 15 IS - 1 PB - SPIE Digital Library PY - 2010 SN - 1083-3668 ER - TY - JOUR AB - The recent development of hybrid imaging scanners that integrate fluorescence molecular tomography (FMT) and x-ray computed tomography (XCT) allows the utilization of x-ray information as image priors for improving optical tomography reconstruction. To fully capitalize on this capacity, we consider a framework for the automatic and fast detection of different anatomic structures in murine XCT images. To accurately differentiate between different structures such as bone, lung, and heart, a combination of image processing steps including thresholding, seed growing, and signal detection are found to offer optimal segmentation performance. The algorithm and its utilization in an inverse FMT scheme that uses priors is demonstrated on mouse images. AU - Freyer, M. AU - Ale, A.B.F. AU - Schulz, R.B. AU - Zientkowska, M. AU - Ntziachristos, V. AU - Englmeier, K.-H. C1 - 120 C2 - 27329 CY - Bellingham, WA TI - Fast automatic segmentation of anatomical structures in x-ray computed images to improve fluorescence molecular tomography reconstruction. JO - J. Biomed. Opt. VL - 15 IS - 3 PB - SPIE PY - 2010 SN - 1083-3668 ER - TY - JOUR AB - There are vibrant developments of optical imaging systems and contrast-enhancing methods that are geared to enhancing surgical vision and the outcome of surgical procedures. Such optical technologies designed for intraoperative use can offer high integration in the operating room compared to conventional radiological modalities adapted to intraoperative applications. Simple fluorescence epi-illumination imaging, in particular, appears attractive but may lead to inaccurate observations due to the complex nature of photon-tissue interaction. Of importance therefore are emerging methods that account for the background optical property variation in tissues and can offer accurate, quantitative imaging that eliminates the appearance of false negatives or positives. In parallel, other nonfluorescent optical imaging methods are summarized and overall progress in surgical optical imaging applications is outlined. Key future directions that have the potential to shift the paradigm of surgical health care are also discussed. AU - Ntziachristos, V. AU - Yoo, J.S. AU - van Dam, G.M.* C1 - 6277 C2 - 28396 CY - Bellingham, WA TI - Current concepts and future perspectives on surgical optical imaging in cancer. JO - J. Biomed. Opt. VL - 15 IS - 6 PB - SPIE PY - 2010 SN - 1083-3668 ER - TY - JOUR AB - Abstract: PURPOSE: The aim of this study was to identify factors predicting initial and late resistance of GI stromal tumor (GIST) patients to imatinib and to document the dose-response relationship in the prognostic subgroups. This study is based on the European Organisation for Research and Treatment of Cancer-Italian Sarcoma Group-Australasian Gastrointestinal Trials Group randomized trial comparing two doses of imatinib in advanced disease. PATIENTS AND METHODS: Initial resistance was defined as progression within 3 months of randomization, and late resistance was defined as progression beyond 3 months. Investigated cofactors include imatinib dose, age, sex, performance status, original disease site, site and size of lesions at trial entry, and baseline hematologic and biologic parameters.RESULTS: Initial resistance was recorded for 116 (12%) of 934 assessable patients and was independently predicted by the presence of lung and absence of liver metastases, low hemoglobin level, and high granulocyte count. Among 818 patients who were alive and progression free at 3 months, 347 subsequent progressions were recorded, and late resistance was independently predicted by high baseline granulocyte count, primary tumor outside of the stomach, large tumor size, and low initial imatinib dose. The impact of initial dose on late resistance was mainly significant in patients with a high baseline granulocyte count (> 5.10(9)/L) and in patients with tumors of GI origin outside of the stomach and small intestine. CONCLUSION: Our study identifies patients for whom initial and/or long-term treatment needs to be improved and patients who require a high initial dose. Correlation of these results with immunohistochemistry and molecular parameters may further help to understand the biologic mechanisms of resistance. AU - Deliolanis, N.C.* AU - Dunham, J.* AU - Wurdinger, T.* AU - Figueiredo, J.L.* AU - Tannous, B.A.* AU - Ntziachristos, V. C1 - 1068 C2 - 26297 TI - In-vivo imaging of murine tumors using complete-angle projection fluorescence molecular tomography. JO - J. Biomed. Opt. VL - 14 IS - 3 PB - Spie-Soc Photoptical Instrumentation Engineers PY - 2009 SN - 1083-3668 ER - TY - JOUR AB - We present a novel fluorescence imaging system developed for real-time interventional imaging applications. The system implements a correction scheme that improves the accuracy of epi-illumination fluorescence images for light intensity variation in tissues. The implementation is based on the use of three cameras operating in parallel, utilizing a common lens, which allows for the concurrent collection of color, fluorescence, and light attenuation images at the excitation wavelength from the same field of view. The correction is based on a ratio approach of fluorescence over light attenuation images. Color images and video is used for surgical guidance and for registration with the corrected fluorescence images. We showcase the performance metrics of this system on phantoms and animals, and discuss the advantages over conventional epi-illumination systems developed for real-time applications and the limits of validity of corrected epi-illumination fluorescence imaging. AU - Themelis, G. AU - Yoo, J.S. AU - Soh, K.S.* AU - Schulz, R.B. AU - Ntziachristos, V. C1 - 754 C2 - 27194 TI - Real-time intraoperative fluorescence imaging system using light-absorption correction. JO - J. Biomed. Opt. VL - 14 IS - 6 PB - Spie-Soc Photoptical Instrumentation Engineers PY - 2009 SN - 1083-3668 ER - TY - JOUR AB - The discovery of new fluorescent proteins (FPs) that emit in the far-red part of the spectrum, where light absorption from tissue is significantly lower than in the visible, offers the possibility for noninvasive biological interrogation at the entire organ or small animal level in vivo. The performance of FPs in deep-tissue imaging depends not only on their optical characteristics, but also on the wavelength-dependent tissue absorption and the depth of the fluorescence activity. To determine the optimal choice of FP and illumination wavelength, we compared the performance of five of the most promising FPs: tdTomato, mCherry, mRaspberry, mPlum, and Katushka. We experimentally measured the signal strength through mice and employed theoretical predictions to obtain an understanding of the performance of different illumination scenarios, especially as they pertain to tomographic imaging. It was found that the appropriate combination of red-shifted proteins and illumination wavelengths can improve detection sensitivity in small animals by at least two orders of magnitude compared with green FP. It is also shown that the steep attenuation change of the hemoglobin spectrum around the 600-nm range may significantly affect the detection sensitivity and, therefore, necessitates the careful selection of illumination wavelengths for optimal imaging performance. AU - Deliolanis, N.C.* AU - Kasmieh, R.* AU - Wurdinger, T.* AU - Tannous, B.A.* AU - Shah, K.* AU - Ntziachristos, V.* C1 - 3647 C2 - 25922 CY - Bellingham, WA SP - 0440081-0440089 TI - Performance of the red-shifted fluorescent proteins in deep-tissue molecular imaging applications. JO - J. Biomed. Opt. VL - 13 IS - 4 PB - SPIE PY - 2008 SN - 1083-3668 ER -