This PDF file contains the front matter associated with SPIE Proceedings Volume 11949, including the Title Page, Copyright information, Table of Contents, and Conference Committee listings.

Fluorescence imaging has been used for quite some time in microscopy, preclinical and medical imaging, as well as in other domains. There has been interest in using the time-behaviour of fluorophores to gain additional information. This time-behaviour, called the fluorescence lifetime, is a property of the fluorophore and can also reveal information about its environment through modulation of this lifetime. Fluorescence-lifetime imaging could improve imaging of existing fluorescent contrast agents or could enable novel applications. The tauCAM, based on the Current-assisted photonic sampler (CAPS), is being developed at our research department with the purpose of achieving real-time fluorescence lifetime imaging. Previous versions have already shown some results in doing lifetime imaging through experiments and demonstrations. Elaborate characterisation of its imaging capabilities in this domain has yet to be performed due to the lack of standardisation and phantoms available for lifetime imaging. In this publication we will discuss the (real-time) lifetime and intensity imaging capabilities of the tauCAM, the latest iteration of our CAPS camera, housing a new 64×64-pixel sensor. The groundwork will be laid for the development of phantoms for lifetime imaging based on phantoms made for fluorescence intensity imaging. These will in turn be measured using reference equipment and used to characterize the accuracy and precision of the results from the tauCAM.

Personalized medicine is one of the main directions in current cancer care. To support this trend, Modulight has designed a laser illumination platform with real-time spectral monitoring to adjust treatments based on each patient’s optical properties of the tissue, providing more personalization to light-based treatments. The laser has been designed to illuminate and retrieve spectral data from the tumor tissue simultaneously from up to eight different locations. The medical laser is cloud-connected, and all diagnostic data is downloaded in real time into the analytics server to assist in the personalized treatment decisions. This enables machine learning and AI-based data analytics to process recorded data to make more informed treatment decisions and deliver the best treatment outcomes to patients. The laser with this optical monitoring feature is currently being evaluated in glioblastoma trials where illumination can be tailored through spectral monitoring of the fluorescent drug and optical properties of the treated tissue.

Water is a fundamental component of many biological systems. The ability to detect water therefore provides great insight into system functionality, particularly in the development of disease. In this work, the high interaction of terahertz radiation with water, paired with the dependence of the dynamics of water molecules with varying temperature, is utilised to monitor changes in the composition of bone tissue. Heterotopic ossification (HO) bone samples and deionised free water are measured using terahertz time-domain spectroscopy for varying environmental temperatures, for prospective use in disease diagnosis.

Tissue biopsy and histological evaluation is the gold standard for disease diagnosis including cancer. For example, a punch several millimeters in diameter is often used to biopsy suspicious skin sites. The biopsy is then formalin fixed, paraffin embedded, sectioned, stained with hematoxylin and eosin (H&E), and examined by a pathologist. While this process has been the gold standard for decades, two limitations are recognized. First, the biopsy is invasive with a limited number that can be reasonably tolerated by the patient. Second, the tissue processing steps are slow. We report an alternative approach consisting of a laser microbiopsy for harvest of sub-microliter (<1 mm³) tissue sections combined with rapid virtual H&E staining methods. A Ho:YAG laser (Lumenis P120) was shaped into an annular beam and focused onto ex vivo porcine skin. The epidermis and dermis were laser cut and the tissue section in the center of the annulus was ejected and collected by an overlying glass coverslip. Tetrafluoroethane (R134A) was sprayed at the ablation site prior to ablation and at the collected tissue section post ablation to limit thermal damage and preserve histological features. Two virtual H&E imaging methods were tested with confocal microscopy. The first combined acridine orange fluoresce with reflectance. The second combined acridine orange and sulforhodamine 101 fluorescence. For each method, the two channels were false colored and combined to create virtual H&E images. Virtual H&E images show histological features, including cell nuclei. Laser microbiopsy is minimally invasive, harvesting tissue sections on the order of 0.01 to 0.1 mm³, and tissue processing is rapid requiring 2 min or less for staining. Laser microbiopsy is a promising candidate technique for rapid minimally invasive diagnosis.

The distinction between tumor and healthy tissue is highly important during an oncological surgery but can be challenging. Optical methods for precise in situ tumor demarcation would be helpful to guide surgery, and thus easy-to-use systems are of high demand. Here, we present a novel MEMS-based confocal laser scanning microscope, named LSC-Onco, for tumor demarcation in oncological surgery. The measurement head of the microscope exhibits a compact size of (11x17x40) cm³ and is intended for use in a clinical environment. It includes a commercially available apochromatic 20x microscope objective with a working distance of 1.0 mm. For a sample overview, a subminiature camera with a field of view of 500 μm in diameter together with a Koehler illumination unit is integrated. Furthermore, for image slicing a z-shifter with a long distance travel range of 2000 μm and 5 nm minimum step size is included. Beam-splitters, filters, micro-photomultiplier tubes and all necessary driving- and read-out electronics are integrated into the measurement head. The core component of the laser scanning microscope is a proprietary electrostatically driven dual-axis MEMS scanning mirror developed at the Fraunhofer IPMS. This device features a quasi-static axis, a second resonant axis and is equipped with an elliptical mirror plate. The system can operate in a dual wavelength mode with fiber-coupled diode lasers at 488 nm and 638 nm. Using the LSC-Onco microscope and fluorophore-coupled tumor-specific antibodies, we visualized tumor margins in human skin cancer specimens outside the body (ex vivo) as a proof-of-concept.

Label-free imaging has re-emerged as a premier approach for imaging living cells and tissues within their natural environment. Label-free imaging provides a non-destructive, high throughput platform for understanding and defining the biophysical states of cells. We anticipate that the real-time spatially-resolved information about the biophysical states of cells will be useful for evaluating and quantifying the changes of these states in response to a variety of external interventions. Here we present a portable high-resolution microscopy system which combines five imaging channels, including four simultaneously excited multiphoton imaging channels (3-photon, 2-photon, third and second harmonic) and wide-field near-infrared imaging.

Transserosal optical coherence tomography (OCT) with angiography modality (OCTA) provides real-time label-free visualization of the intestinal structure and blood vessels networks with a spatial resolution about 10-15 µm. This method is a perspective for intraoperative use in abdominal surgery, for example, for determining the depth of ischemic damage to the gut. The paper devoted to analysis the quality of OCT/OCTA data obtained from small intestine of 4 subjects - rat, rabbit, minipigs and humans. The subjects have different thickness of intestinal wall and blood circulation conditions. It was shown, that the intestine of small laboratory animals (rats and rabbits) is convenient for studying with OCT/OCTA: it can be easily stabilized by moving the intestine loop outside the body, which, together with a rigidly fixed probe, minimizes the number of possible motion artifacts. Therefore, OCT/OCTA criteria of structural changes in the intestinal wall and microcirculation disorders during ischemia, important for clinical applications, were established on these objects. Large animals (minipigs) and human proved to be a troublesome subjects for obtaining high-quality OCT/OCTA data: powerful peristaltic movements, pronounced pulse wave and the inability to take the object out of the body in order to exclude the influence of respiratory and other types of the body movements led to a sharp increase in the amount of OCT/OCTA images with artifacts (up to 39% in humans). However, in patients and minipigs the microstructure of intestinal layers was more informative than in small animals due to increased thickness. Therefore, it allowed visualize tissues in more detail: in particular, verify peritoneum edema and intramuscular fluid buildup. The study was performed under support of RFBR grant No.19-75-10096.

Light-emitting diodes (LEDs) are widely used lighting applications that have several advantages over conventional lamp light sources, including higher mechanical robustness, faster response time, less energy consumption, and longer lifetime. In this study, we investigated the feasibility of LED-based absorption spectrophotometry. To implement an ultraviolet-visible (UV-VIS) absorption spectrophotometer, a light source was prototyped consisting of two types of LEDs: a UV LED (340 nm) and a broadband white LED (about 380-800 nm). A dichroic filter was used to combine the light of the two types of LEDs. Compared with conventional lamp light sources, the area of LED light emission is quite small and the emitting properties are not uniform. Therefore, to make the irradiance areas of two LEDs uniform, we applied an optical diffuser to the ultraviolet LED to widen the light-emitting area and broadly cover the irradiance areas from a white LED. This optical alignment enabled a configuration to withstand the mounting tolerance of approximately ±0.3 mm of LEDs on substrates. Another issue is that temperature must be stabilized because electrical and optical properties of LEDs strongly depend on temperature. Thus, we utilized a Peltier controller to precisely control temperature control of an LED-mounted substrate (less than ±0.01°C) and to achieve the target value of temporal drift within ±0.05% per hour of light intensity in photometric signals. The obtained results suggest that our developed LEDbased light source should be useful for a UV-VIS absorption spectrophotometer.

Multimodal sapphire scalpel for intraoperative diagnosis and therapy. The multimodal sapphire scalpel was developed using the edge-defined film-fed growth technique aided by the cutting edge mechanical sharpening. The sapphire properties are combined with the presence of as-grown hollow internal capillary channels for the optical fibers accommodation. Thanks to the features of the sapphire scalpel, multimodal optical diagnosis of tissues with their dissection became available. The attained results justified a strong potential of the sapphire scalpel to become an efficient tool for minimizing the volume of the normal tissue removal around the tumor by detecting the tumor margins.

Edema is a condition in which extracellular fluid accumulates excessively in the subcutaneous tissue, and the prevalence of lower limb edema is high in the elderly. There is a method called pitching test as a method to evaluate the condition of edema, but it is subjective scoring, and it is difficult to evaluate quantitatively. Therefore, the purpose of this study is to express the mechanical properties of edema using a viscoelastic model with the aim of quantitative evaluation of edema. In the pitting-test, compression is applied at a constant pressure for 10 seconds, and evaluation is performed using the depth of the indentation. In this study, we use a three-element viscoelastic model with two viscosity and one elasticity, which is also used to evaluate the viscoelasticity of the skin. The viscoelastic parameter is estimated by measuring the temporal change in displacement when pressure is applied to the edema using a laser displacement meter. By using the viscoelasticity parameter, it is considered that not only the indentation but also the return method will be different, and it may be possible to evaluate edema that could not be evaluated so far. In this paper, we report the measurement results using the edema phantom.

Omnidirectional side-view images from miniaturized catadioptric endoscopes may be used to generate mosaics of the epithelium of tubular organs, enabling the longitudinal monitoring of surface pathologies. Here, previous results are extended to create three-dimensional sub-mm resolution 3.5 cm × 360° reconstructions of pediatric cardiac phantoms. From image stacks with a single annulus of best focus captured via parabolic mirrors, adjacent rings within the focused region may be used to infer depth via parallax while rings of best focus are used to color the inferred geometry. Potential applications include digital reconstruction of pediatric and small-animal organs for diagnostics and surgical guidance at near-cellular resolution.

Urinalysis is an essential diagnostic tool in evaluating health and disease of the genitourinary tract. A urinalysis typically consists of dipstick testing, which can detect red blood cells, white blood cells, and bacteria, and microscopic evaluation of urine sediment after centrifugation, which further reveals other biomarkers such as crystals and casts. In the in-patient hospital setting, urinalysis is typically ordered after disease is suspected, drawing urine from the collection bag of a foley catheter and sending the sample to a core laboratory for analysis. To improve access to urine biomarkers, we propose a holographic lens free imaging (LFI) system that could allow automated bedside urine screening. LFI is uniquely suited for this task due to its low-cost, compact nature, and its ability to reconstruct large volumes from a single hologram without the depth-of-field trade-off of conventional microscopy. Here, we build and demonstrate an LFI system capable of detecting important biomarkers such as E. Coli in PBS and red blood cells, casts, and crystals in urinalysis control phantoms. In the future, this compact system could be connected to the drainage tube of a patient's foley catheter to enable real-time screening of urine at the bedside.

Endoscopic surgery has been widely adopted across specialties because it reduces patient trauma, risk, and recovery time as compared to open procedures. The foremost challenge of endoscopic surgery is the inability to see in three dimensions, a disadvantage that significantly increases procedure time and uncertainty by inhibiting depth perception as well as localization and measurement capability. State-of-the-art approaches in endoscopic 3D measurement are largely based on a combination of structured light and stereo vision, but are limited in their robustness and applicability to clinical workflow. Both approaches require a large baseline and are not supported by most handheld off-the-shelf endoscopes; stereo methods specifically are sensitive to scenes lacking features or containing disturbances such as smoke and specular reflections, which are common in surgery. To address these issues, we propose an alternative method for 3D measurement based on time-of-flight (TOF), a depth sensing modality which is inherently monocular and known to be insensitive to featureless scenes and many types of disturbances. Specifically, we develop a TOF imaging module adapter compatible with off-theshelf endoscopes and demonstrate single-shot, sub-millimeter 3D measurement accuracy on animal tissue. These results are significant because they suggest widespread compatibility with existing operating room equipment and workflow and applicability to a wide variety of clinically relevant surgical tasks including measurement of tumors, hernias, and anastomoses, intra-operative registration of the surgical scene to high-quality static 3D imaging data, and control of surgical robots.

We present a needle-injectable wire-free breast lesion localization device that utilizes multi-colored, radio-frequency (RF)-powered LEDs for precise visual guidance during lumpectomy procedures. A red LED provides deep tissue (<10 cm) visible guidance to the lesion, while a green/yellow LED provides more precise close range (<1 cm) visual guidance. The biocompatible device includes an impedance matching circuit and miniature receiver coil optimized for operation in the 6.78 MHz industrial, scientific, and medical RF band. We show that the implant is visible through >5 cm of in vitro and ex vivo breast tissue phantoms using less than 2W of transmitted RF power.