In this paper, the changes in muscle deoxygenation trends during a sustained isometric quadriceps (chair squat/half squat) endurance exercise were evaluated among twelve male subjects and the relationship between muscle oxygenation and endurance times was investigated by means of functional near-infrared spectroscopy (fNIRS). Neuromuscular activation and predictions of muscle performance decrements during extended fatiguing task was investigated by means of surface electromyography (sEMG). The results of the study showed that in the subjects who maintained exercise longer than five minutes (group 1), mean Hb recovery time (33 [sec.]) was 37.4% less than the others (group 2, 52.7 [sec.]). Also mean HbO₂ decline amplitude (2.53 [a.u.] in group 1 and 2.07 [a.u.] in group 2) and oxy decline amplitude (8.4 [a.u.] in group 1 and 3.04 [a.u.] in group 2) in the beginning of squat exercise are found to be 22.6% and 176.9% bigger in these group. For the EMG parameters, mean slope of MNF and MDF decline are found to be 57.5% and 42.2% bigger in magnitude in group 2 which indicates higher degree of decrement in mean and median frequencies although their mean squat duration time is less. This indicates higher index of fatigue for this group. It is concluded that training leads to altered oxygenation and oxygen extraction capability in the exercising muscle and investigated fNIRS parameters could be used for endurance evaluation.

Monitoring the oxygenation of skeletal muscle tissues during rest to work transient provides valuable information about the performance of a particular tissue in adapting to aerobic glycolysis. In this paper we analyze the temporal relation of O₂ consumption with deoxy-hemoglobin (Hb) signals measured by functional Near Infrared Spectroscopy (fNIRS) technique during moderate isotonic forearm finger joint flexion exercise under ischemic conditions and model it with a mono exponential equation with delay. The time constants of fitting equation are questioned under two different work loads and among subjects differing in gender. Ten (6 men and 4 women) subjects performed isotonic forearm finger joint flexion exercise with two different loads. It is shown that under the same load, men and women subjects generate similar time constants and time delays. However, apparent change in time constants and time delays were observed when exercise was performed under different loads. When t-test is applied to compare the outputs for time constants between 0.41202 Watts and 0.90252 Watts, P value of 9.3445x10^-4 < 0.05 is observed which implies that the differences between the time constants are statistically significant. When the same procedure is applied for the time delay comparison, P value of 0.027<0.05 is observed which implies that also the differences between the time delays are statistically significant.

We describe the use of Fourier holography for recording the spatially resolved complex angular scattering spectrum from scattering samples over wide fields of view in a single or few image captures. Without resolving individual scatterers, we are able to differentiate between spherical scatterers of different sizes in solutions containing mixtures by correspondence with Mie theory. In this paper, we describe the theory behind Fourier holographic light scattering angular spectroscopy and demonstrate its performance experimentally. Such methods represent potentially efficient alternatives to the time consuming and laborious conventional procedure of light microscopy, image tiling and inspection for the characterization of morphology over wide fields of view.

Small animal models are employed to simulate disease in humans and to study its progression, what factors are important to the disease process, and to study the disease treatment. Biomedical imaging modalities such as magnetic resonance imaging (MRI) and Optical Tomography make it possible to non-invasively monitor the progression of diseases in living small animals and study the efficacy of drugs and treatment protocols. MRI is an established imaging modality capable of obtaining high resolution anatomical images and along with contrast agents allow the studying of blood volume. Optical tomography, on the other hand, is an emerging imaging modality, which, while much lower in spatial resolution, can separate the effects of oxyhemoglobin, deoxyhemoglobin, and blood volume with high temporal resolution. In this study we apply these modalities to imaging the growth of kidney tumors and then there treatment by an anti-VEGF agent. We illustrate how these imaging modalities have their individual uses, but can still supplement each other and cross validation can be performed.

In-vivo image-based multi-spectral images have typical problems in image acquisition, registration, visualization and analysis. As its spatial and spectral axes do not have the same unit, standard image algorithms often do not apply. The image size is often so large that it is hard to analyze them interactively. In a clinical setting, image motion will always occur during the acquisition times up to 30 seconds, since most (elderly) patients often have difficulty to retain their poses. In this paper, we discuss how the acquisition, registration, display and analysis can be optimized for in-vivo multi-spectral images.

For characterization of suspicious breast lesions, we used a dual modal imaging scheme integrating a hand-held near infrared imager and a portable ultrasound probe. The functional properties of the suspicious lesion and the surrounding tissue were reconstructed based on the diffuse reflectance measurement of the near infrared light and the ultrasound measurement of the tumor morphology. The near infrared/ultrasound dual modal imaging system has been validated through a series of bench top tests where tumor simulators with various absorptions were embedded at different depth in a liquid tissue-simulating phantom. The clinical trial of the imaging scheme was conducted on 44 subjects with suspicious breast lesions identified by mammography and/or ultrasound. Both near infrared and ultrasound data were collected from the area of the suspicious breast lesion and from the adjacent reference breast tissue. The clinical trial demonstrates that the dual modal imaging system can reach up to 71% of diagnostic sensitivity and 58% of specificity in detecting breast carcinoma. This may indicate that the system could potentially be used in breast cancer detection adjunctive with mammography.

We present a combination of topography measurements based on digital fringe projection and blood flow imaging based on Laser Doppler Imaging (LDI). Both techniques are optical, non-contact and high-speed whole-field methods well suited for in-vivo measurements on the skin. Laser Doppler perfusion imaging is an interferometric technique used for visualization of two-dimensional (2D) maps of blood flow. Typically the measured sample has a surface with a specific 3D relief. In many cases the sample relief can be of importance for correct interpretation of the obtained perfusion data. We combined the topography and the blood flow data obtained from the same object. The structural information provided by the topography is completed by the functional images provided by LDI.

Intravital microscopy of cancer is a well established tool that provides direct visualization of the tumor cycle. It traditionally involves one of several strategies: invasive subcutaneous (SC) implantation of tumors followed by surgical opening of skin flaps for imaging, techniques utilizing skin fold chambers and implanted optical windows or intradermal injections under 200μm from the skin surface. All of these techniques allow the use of fluorescent proteins as markers for biologically significant constituents. However, observation methods utilizing skin-flaps, skin-fold chambers and optical windows are invasive and tend to alter the immune environment of the tissue and/or limit the duration of studies that can be performed. If implanted correctly, intradermally injected tumors can be minimally invasive, will not require biopsies or surgical intervention to observe and are accessible for direct transdermal imaging with a number of in vivo modalities. We present our work in the development of a small animal intravital microscopy workstation that allows the acquisition of different contrast imaging modalities: reflectance confocal, wide field epifluorescence, multiphoton and second harmonic generation (SHG). The images are acquired pair-wise simultaneously and sequentially in time. The aim of our instrumentation is to gather all information generated by the single probing beam via the reflected or back-scattered signal, SHG signal and various fluorescence signals. Additionally, we also present our development of a microscopic tissue navigation technique to mark, label and track sites of interest. This technique enables us to revisit sites periodically and record, with different imaging contrasts, their biological changes over time.

In this paper, we introduce a novel and efficient algorithm for reconstructing the 3D locations of tumor sites from a set of 2D bioluminescence images which are taken by a same camera but after continually rotating the object by a small angle. Our approach requires a much simpler set up than those using multiple cameras, and the algorithmic steps in our framework are efficient and robust enough to facilitate its use in analyzing the repeated imaging of a same animal transplanted with gene marked cells. In order to visualize in 3D the structure of the tumor, we also co-register the BLI-reconstructed crude structure with detailed anatomical structure extracted from high-resolution microCT on a single platform. We present our method using both phantom studies and real studies on small animals.

We present a new method for the calculation of a blood oxygen level dependent (BOLD) signal which is meaningful for a quantitative comparison with near infrared spectroscopy (NIRS) data. Since optical tomography of the human brain still poses several difficulties, in this study we propose a way to project the BOLD signal on a two-dimensional (2D) map for comparison with NIRS data. The underlying assumption is that fMRI and NIRS are sensitive to similar aspects of the hemodynamic changes occurring during a functional task, and therefore they should have similar spatial and temporal features. We present a case study of functional activation during a finger-tapping test where we used the new method for the calculation of BOLD signal. For every optical source-detector pair we calculated a weighted BOLD signal by using a photon hitting-density weight function, and by using a simple back-projection algorithm we were able to generate BOLD 2D maps. We found that the weighted BOLD signals calculated from different source-detector pairs scale in a similar way to the corresponding oxy and deoxy-hemeoglobin concentration changes calculated from NIRS data, for most of the time range of the task. Therefore the BOLD 2D maps were quantitatively similar to the optical maps calculated at different times during the protocol.

Computer vision advancements have not till now achieved the accurate 3D reconstruction of objects smaller than 1cm diameter. Although this problem is of great importance in dermatology for Non Melanoma Skin Cancer diagnosis and therapy, has not yet been solved. This paper describes the development of a novel volumetric method for NMSC animal model tumors, using a binocular vision system. Monitoring NMSC tumors volume changes during PDT will grant important information for the assessment of the therapeutic progress and the efficiency of the applied drug. The vision system was designed taking into account the targets size and the flexibility. By using high resolution cameras with telecentric lenses most distortion factors were reduced significantly. Furthermore, z-axis movement was possible without requiring calibration, in contrary to wide angle lenses. The calibration was achieved by means of adapted photogrammetric technique. The required time for calibrating both cameras was less than a minute. For accuracy expansion, a structured light projector was used. The captured stereo-pair images were processed with modified morphological filters to improve background contrast and minimize noise. The determination of conjugate points was achieved via maximum correlation values and region properties, thus decreasing significantly the computational cost. The 3D reconstruction algorithm has been assessed with objects of known volumes and applied to animal model tumors with less than 0.6cm diameter. The achieved precision was at very high levels providing a standard deviation of 0.0313mm. The robustness of our system is based on the overall approach and on the size of the targets.

For planning, simulation and documentation of interventions in maxillofacial surgery high resolving soft tissue information of the human face in upright position is needed. This information can be gained by holographic methods, which allow a recording of the whole face in an extremely short time period, so that no movement artefacts occur. The hologram is recorded with a single laser pulse of 25 ns duration and stored in photosensitive material. After automated wet-chemical processing, the hologram is optically reconstructed with a cw-laser. During the optical reconstruction, a light field, which is a one-to-one three-dimensional representation of the recorded face, emerges at its original position and is digitized into a set of two-dimensional projections. Digital image processing leads to merging of these projections into a three-dimensional computer model. Besides the topometric information, a high resolving pixel precise texture is also extracted from the holographic reconstruction and used for the texturing of the computer models. The use of mirrors allows the simultaneous recording of three different views of the face with one laser pulse. The three different views of the face can be combined easily, because they are simultaneously recorded. Thus a recording range of approximately 270 degrees is achieved. In addition to the medical application, high resolving and textured computer models of faces are of tremendous importance for facial reconstruction in anthropology, forensic science and archaeology.

Many surgical techniques are currently shifting from the more conventional, open approach towards minimally invasive laparoscopic procedures. Laparoscopy results in smaller incisions, potentially leading to less postoperative pain and more rapid recoveries . One key disadvantage of laparoscopic surgery is the loss of three-dimensional assessment of organs and tissue perfusion. Advances in laparoscopic technology include high-definition monitors for improved visualization and upgraded single charge coupled device (CCD) detectors to 3-CCD cameras, to provide a larger, more sensitive color palette to increase the perception of detail. In this discussion, we further advance existing laparoscopic technology to create greater enhancement of images obtained during radical and partial nephrectomies in which the assessment of tissue perfusion is crucial but limited with current 3-CCD cameras. By separating the signals received by each CCD in the 3-CCD camera and by introducing a straight forward algorithm, rapid differentiation of renal vessels and perfusion is accomplished and could be performed real time. The newly acquired images are overlaid onto conventional images for reference and comparison. This affords the surgeon the ability to accurately detect changes in tissue oxygenation despite inherent limitations of the visible light image. Such additional capability should impact procedures in which visual assessment of organ vitality is critical.

In recent years, the prevalence of in vivo molecular imaging applications has rapidly increased. Here we report on the construction of a multi-modality imaging facility in a pharmaceutical setting that is expected to further advance existing capabilities for in vivo imaging of drug distribution and the interaction with their target. The imaging instrumentation in our facility includes a microPET scanner, a four wavelength time-domain optical imaging scanner, a 9.4T/30cm MRI scanner and a SPECT/X-ray CT scanner. An electronics shop and a computer room dedicated to image analysis are additional features of the facility. The layout of the facility was designed with a central animal preparation room surrounded by separate laboratory rooms for each of the major imaging modalities to accommodate the work-flow of simultaneous in vivo imaging experiments. This report will focus on the design of and anticipated applications for our microPET and optical imaging laboratory spaces. Additionally, we will discuss efforts to maximize the daily throughput of animal scans through development of efficient experimental work-flows and the use of multiple animals in a single scanning session.

We have developed a software platform for multimodal integration and visualization of diffuse optical tomography and magnetic resonance imaging. Novel registration and segmentation algorithms have been integrated into the platform. The multimodal registration technique enables the alignment of non-concurrently acquired MR and DOT breast data. The non-rigid registration algorithm uses two-dimensional signatures (2D digitally reconstructed radiographs) of the reference and moving volumes in order to register them. Multiple two-dimensional signatures can robustly represent the volume depending on the way signatures are generated. An easy way to conceptualize the idea is to understand the motion of an object by tracking three perpendicular shadows of the object. The breast MR image segmentation technique enables a priori structural information derived from MRI to be incorporated into the reconstruction of DOT data. The segmentation algorithm is based on "Random walkers". Both registration and segmentation algorithms were tested and have shown promising results. The average Target Registration Error (TRE) for phantom models simulating the large breast compression differences was always below 5%. Tests on patient datasets also showed satisfying visual results. Several tests were also conducted for segmentation assessment and results have shown high quality MR breast image segmentation.

This paper presents the design, instrumentation, and performance of a rapid imaging near-infrared diffuse optical tomography system that is capable of collecting tomographic measurements at 35 frames per second. The video-rate tomographic data acquisition is achieved by spectral wavelength encoding of the sources, which allows many sources to be input into the tissue at the same time, followed by spectral-decoding of all detection channels in parallel using a spectrometer and CCD detector. The combination of spectral-decoding of the source lights horizontally in a spectrometer and spatial-separation of the detector positions vertically at the entrance slit provides continuous data for the entire set of source-detector pairs. A data acquisition speed of 35Hz frame rate was achieved with the use of the CCD operating in frame-transfer mode. The described system features 8 sources at an overall 785nm center band with average of 1.25nm spacing in wavelength and 8 detectors evenly deployed in a 27mm array designed for imaging with small animal tissues. The system's imaging characteristics as well as examples of capturing transient changes of absorption in the dynamic phantom are presented.

In this paper, we report a nonlinear 3D image reconstruction algorithm featuring 3D finite element forward modeling with an iterative multi-right-hand-side solver and an automatic mesh generation technique for efficient geometry modeling. The forward mesh was generated based on 3D tomosynthesis images acquired simultaneously with optical measurements. An efficient iterative solver based on a QMR algorithm with the capacity of solving multi-RHS was used to enhance the computational efficiency. The mesh generation algorithm was developed based on a moving mesh process and is able to generate high-quality mesh with low computational complexity. In addition, an approximated adjoint method was used to form the Jacobian matrix for the inverse problem. The performance was satisfactory in numerical simulations. For a typical reconstruction, the run-time was under 5 minutes on a Pentium-based PC. It is worth mentioning that the mesh generation module not only works for binary 2D or 3D image stacks, but also for any other binary description of the object, which makes it generalizable to many other potential applications.

Gadolinium (Gd) pharmacokinetics are useful in diagnosis of breast cancer with MRI; previous work has suggested that the pharmacokinetics of indocyanine green (ICG) may prove to be similarly useful in optical mammography. Here, we describe a fast optical imaging device to acquire images of ICG kinetics simultaneously with Gd kinetics and coregister the images. This direct comparison between the widely accepted Gd diagnostic techniques and optical methods is essential for clinical acceptance of optical techniques by the radiological community.