Peripheral artery disease (PAD) affects approximately 12 million people in the US. The disease is caused by an accumulation of plaque in arteries, which leads to stenosis and reduction in blood flow. In advanced cases, surgery or endovascular interventions are required to re-establish blood flow to the extremities. In over 40% of these cases a second intervention is required within 12 months. Therefore, accurate monitoring the blood flow in the feet of these patients is crucial. In this study, dynamic vascular optical spectroscopy was used to assess perfusion in 4 different angiosomes of 25 patients who underwent a surgical intervention. Imaging was performed just before the intervention, 4 hours later and 1 month later. Each optical spectroscopy session consisted in inflating a thigh pressure cuff to 60 mmHg, maintaining the pressure for 60 seconds and releasing it, then repeating the procedure while inflating the cuff to 100 mmHg. Totalhemoglobin [THb] time traces for each angiosome were calculated. We found a strong correlation between the dynamic shapes of the THb-signals obtained before the intervention, 3 hours after the intervention and 1 month later and the longterm outcome of the procedure.
Infantile hemangiomas (IH) are common vascular growths that occur in 5-10% of neonates and have the potential to cause disfiguring and even life-threatening complications. Currently, no objective tool exist to monitor either progression or treatment of IH. To address this unmet clinical need, we have developed a handheld wireless device (HWD) that uses diffuse optical spectroscopy for the assessment of IH. The system employs 4 wavelengths (l=780nm, 805nm, 850nm, and 905nm) and 6 source-detector pairs with distances between 0.6 and 20 mm. Placed on the skin surface, backreflection data is obtained and a multispectral evolution algorithm is used to determine total hemoglobin concentration and tissue oxygen saturation. First results of an ongoing pilot study involving 13 patients (average enrollment age = 25 months) suggest that an increase in hypoxic stress over time can lead to the proliferation of IH. Involuting IH lesions showed an increase in tissue oxygen saturation as well as a decrease in total hemoglobin.
Dynamic optical tomographic imaging has shown promise in diagnosing and monitoring peripheral arterial disease
(PAD), which affects 8 to 12 million in the United States. PAD is the narrowing of the arteries that supply blood to the
lower extremities. Prolonged reduced blood flow to the foot leads to ulcers and gangrene, which makes placement of
optical fibers for contact-based optical tomography systems difficult and cumbersome. Since many diabetic PAD
patients have foot wounds, a non-contact interface is highly desirable. We present a novel non-contact dynamic
continuous-wave optical tomographic imaging system that images the vasculature in the foot for evaluating PAD. The
system images at up to 1Hz by delivering 2 wavelengths of light to the top of the foot at up to 20 source positions
through collimated source fibers. Transmitted light is collected with an electron multiplying charge couple device
(EMCCD) camera. We demonstrate that the system can resolve absorbers at various locations in a phantom study and
show the system’s first clinical 3D images of total hemoglobin changes in the foot during venous occlusion at the thigh.
Our initial results indicate that this system is effective in capturing the vascular dynamics within the foot and can be used
to diagnose and monitor treatment of PAD in diabetic patients.
Whole body in vivo optical imaging of small animals has widened its applications and increased the capabilities for preclinical researches. However, most commercial and prototype optical imaging systems are camera-based systems using epi- or trans- illumination mode, with limited views of small animals. And for more accurate tomographic image reconstruction, additional data and information of a target animal is necessary. To overcome these issues, researchers have suggested several approaches such as maximizing the detection area or using the information of other highresolution modalities such as CT, MRI or Ultrasound, or using multi-spectral signals. As one of ways to maximizing the detection area of a target animal, we present a new fluorescence and bioluminescence imaging system for small animals, which can image entire surface of a target animal simultaneously. This system uses double mirror reflection scheme and it consists of input unit, imaging unit with two conical mirrors, the source illumination part and the surface scanner, and the detection unit with an intensified CCD camera system. Two conical mirrors are configured that a larger size mirror captures a target animal surface, and a smaller size mirror projects this captured image onto a CCD camera with one acquisition. With this scheme, we could capture entire surface of a target animal simultaneously and improve back reflection issue between a mirror and an animal surface of a single conical mirror scheme. Additionally, we could increase accessibility to an animal for multi-modality integration by providing unobstructed space around a target animal.
Infantile hemangiomas (IH) are common vascular growths that occur in 5-10% of neonates and have the potential to cause disfiguring and even life-threatening complications. With no objective tool to monitor IH, a handheld wireless device (HWD) that uses diffuse optical spectroscopy has been developed for use in assessment of IH by measurements in absolute oxygenated and deoxygenated hemoglobin concentration as well as scattering in tissue. Reconstructions of these variables can be computed using a multispectral evolution algorithm. We validated the new system by experimental studies using phantom experiments and a clinical study is under way to assess the utility of DOI for IH.
Diffuse optical tomography has shown promising results as a tool for breast cancer screening and monitoring response to chemotherapy. Dynamic imaging of the transient response of the breast to an external stimulus, such as pressure or a respiratory maneuver, can provide additional information that can be used to detect tumors. We present a new digital continuous-wave optical tomography system designed to simultaneously image both breasts at fast frame rates and with a large number of sources and detectors. The system uses a master-slave digital signal processor-based detection architecture to achieve a dynamic range of 160 dB and a frame rate of 1.7 Hz with 32 sources, 64 detectors, and 4 wavelengths per breast. Included is a preliminary study of one healthy patient and two breast cancer patients showing the ability to identify an invasive carcinoma based on the hemodynamic response to a breath hold.
Continuous wave optical tomography is non-ionizing, uses endogenous contrast, and can be performed quickly and at
low cost which makes it a suitable imaging modality for breast cancer screening. Using multiple wavelengths of light to
illuminate the breast at various angles, three-dimensional images of the distribution of chromophores such as oxy- and
deoxy-hemoglobin can help identify cancerous tissue. Dynamic optical imaging can provide additional insight into
cancer characteristics such as angiogenesis and metabolism. Here we present the first clinical data acquired with our
novel digital breast imaging system. This system is based upon a Digital Signal Processor (DSP) architecture that
leverages the immediate digitization of acquired analog data to reduce noise and quickly process large amounts of data.
Employing this new instrument we have investigated the dynamic changes due to a breath hold and its potential for use
in breast cancer screening. Over the course of a breath hold, images have been collected simultaneously from both
breasts at a rate of 1.7 frames per second with 32 sources and 64 detectors per breast and four wavelengths of light at
765, 805, 827, and 905nm. Initial results involving one healthy volunteer and one breast cancer patient support the
potential use of dynamic imaging for breast cancer detection.
Dynamic optical imaging is increasingly applied to clinically relevant areas such as brain and cancer imaging. In this approach, some external stimulus is applied and changes in relevant physiological parameters (e.g., oxy- or deoxyhemoglobin concentrations) are determined. The advantage of this approach is that the prestimulus state can be used as a reference or baseline against which the changes can be calibrated. Here we present the first application of this method to the problem of characterizing joint diseases, especially effects of rheumatoid arthritis (RA) in the proximal interphalangeal finger joints. Using a dual-wavelength tomographic imaging system together with previously implemented model-based iterative image reconstruction schemes, we have performed initial dynamic imaging case studies on a limited number of healthy volunteers and patients diagnosed with RA. Focusing on three cases studies, we illustrated our major finds. These studies support our hypothesis that differences in the vascular reactivity exist between affected and unaffected joints.
Optical probing of hemodynamics is often employed in areas such as brain, muscular, and breast-cancer imaging. In
these studies an external stimulus is applied and changes in relevant physiological parameters, e.g. oxy or deoxyhemoglobin
concentrations, are determined. In this work we present the first application of this method for
characterizing joint diseases, especially effects of rheumatoid arthritis (RA) in the proximal-interphalangeal (PIP)
finger joints. Using a dual-wavelength tomographic imaging system together with previously implemented model-based
iterative image reconstruction schemes, we have performed dynamic imaging case studies on a limited
number of healthy volunteers and patients diagnosed with RA. Inflating a sphygmomanometer cuff placed around
the forearm we elicited a controlled vascular response. We observed pronounced differences between the
hemodynamic effect occurring in healthy volunteers and patients affected by RA.
We describe a new dynamic optical tomography system that is, unlike currently available analog instrumentation, based on digital data-acquisition and filtering techniques. At the heart of this continuous wave instrument is a digital signal processor (DSP) that collects, collates, processes, and filters the digitized data set. A digital lock-in filter that has been designed for this particular application maximizes measurement fidelity. The synchronously-timed processes are controlled by a complex programmable logic device (CPLD) that is also used in conjunction with the DSP to orchestrate data flow. Real-time data rates as high as 140Hz can be achieved. The operation of the system is implemented through a graphical user interface designed with LabVIEW software, Performance analysis shows very low system noise (~600fW RMS noise equivalent power), excellent signal precision (<0.04% - 0.2%) and long-term system stability (<1% over 40 min). A large dynamic range (~195dB) accommodates a wide scope of measurement geometries and tissue types. First experiments on tissue phantoms show that dynamic behavior is accurately captured and spatial location can be correctly tracked using this system.