Overall, the history of clinical fluorescence imaging reflects a continual progression from basic research to sophisticated applications in clinical practice, contributing to improved diagnostics and treatment outcomes. Additionally, clinical phase 0 microdosing molecular imaging studies of fluorescent and/or nuclear labelled therapeutic compounds is providing an unprecedented early clinical evaluation tool of novel therapeutic compounds in terms of biodistribution, pharmacokinetics and in vivo and ex vivo mesoscopic tissue distribution in the target population of interest (e.g. oncology, inflammatory diseases[e.g. inflammatory bowel disease, rheumatoid arthritis], cardiovascular and infectious diseases). This provides important qualitative and quantitative data to better prepare phase I (i.e. PK/BD and dose-modelling) and II clinical studies (i.e. on- and off-target data) for de-risking and a more efficient drug development pathway. An overview of the described applications will be given and the envisioned perspectives for the next 10 years of clinical application of fluorescence / optical imaging in clinical applications.
Organ perfusion has been of interest to surgeons unremittingly as it is generally understood that adequate tissue perfusion prevents morbidity and mortality. A promising objective imaging method that can provide objective and reproducible perfusion imaging is called laser speckle contrast imaging. For this study, a dye-free, instantaneous, continuous and real-time laparoscopic perfusion imaging device called PerfusiX-Imaging was developed. The technology was validated in multiple pre-clinical models as well as a multi-centre study in colorectal surgery. The basic and fundamental (pre-)clinical studies provide evidence that laparoscopic laser speckle contrast imaging is capable of measuring the slightest of perfusion differences in real-time.
Significance: Intraoperative parameters of renal cortical microperfusion (RCM) have been associated with postoperative ischemia/reperfusion injury. Laser speckle contrast imaging (LSCI) could provide valuable information in this regard with the advantage over the current standard of care of being a non-contact and full-field imaging technique.
Aim: Our study aims to validate the use of LSCI for the visualization of RCM on ex vivo perfused human-sized porcine kidneys in various models of hemodynamic changes.
Approach: A comparison was made between three renal perfusion measures: LSCI, the total arterial renal blood flow (RBF), and sidestream dark-field (SDF) imaging in different settings of ischemia/reperfusion.
Results: LSCI showed a good correlation with RBF for the reperfusion experiment (0.94 ± 0.02; p < 0.0001) and short- and long-lasting local ischemia (0.90 ± 0.03; p < 0.0001 and 0.81 ± 0.08; p < 0.0001, respectively). The correlation decreased for low flow situations due to RBF redistribution. The correlation between LSCI and SDF (0.81 ± 0.10; p < 0.0001) showed superiority over RBF (0.54 ± 0.22; p < 0.0001).
Conclusions: LSCI is capable of imaging RCM with high spatial and temporal resolutions. It can instantaneously detect local perfusion deficits, which is not possible with the current standard of care. Further development of LSCI in transplant surgery could help with clinical decision making.
Monitoring the renal cortical microperfusion (RCM) can aid in the determination of an adequate treatment plan to eventually improve transplantation outcome and improve patient care. In this paper we report on a feasibility study on the use of LSCI to monitor RCM in human sized porcine kidneys using an isolated perfusion model and a Lapvas-Imaging speckle imager. Our data shows that there is a discrepancy between overall- and RCM perfusion indicating that the implementation of LSCI during transplant surgery could help with the establishment of an appropriate treatment plan possibly decreasing the chance of renal allograft rejection.
Photodynamic therapy (PDT) has been used clinically for the treatment of head and neck cancer. The effectiveness of PDT is often strongly dependent on fluence rate. Targeted photo-immunotherapy (PIT) may reduce the adverse effects of non-targeted PDT. The in-vivo distribution of the anti-EGFR targeted conjugate Cetuximab-IRDye700DX was investigated. Vascular and tumor responses were determined with respect to fluence rate.
Intra-vital confocal microscopy of skin-fold chambers with the EGFR-overexpressing OSC-19 tumor showed peak tumor fluorescence 24 hrs after administration. Tumor to normal ratio was 3.1±1.6 (n=8). Tumor vascular responses were determined by imaging rhodamine-dextran extravasation. Two hrs after illumination (24 hr DLI, 100 J.cm-2 at 50 mW.cm-2) showed no leakage in 3 of 4 animals and stasis in 1. Normal vasculature showed mild to severe constriction of larger vessels up to 48 hrs after illumination. Subcutaneous OSC-19 tumors were transdermally illuminated with 100 J.cm-2 at 20, 50 and 150 mW.cm-2. Control tumors took 5.3±1.1 days to grow to 200%. All animals treated with 20 mW.cm-2 showed no tumor up to 90 days post treatment (n=4) compared to 1 of 4 in the 50 and 150 mW.cm-2 groups. The remaining tumors reached 200% after 17.9±5.2 and 19.5±7.4 days. Crust formation of the overlying skin was observed at low fluence rate.
Cetuximab-IRDye700DX showed significant tumor to normal ratio. Normal tissue responses like vascular effects and crust formation of the skin was observed and may be caused by conjugate still present in the circulation. The effect of targeted-PIT is strongly dependent on fluence rate.
When a biological tissue is illuminated with coherent light, an interference pattern will be formed at the detector, the so-called speckle pattern. Laser speckle contrast imaging (LSCI) is a technique based on the dynamic change in this backscattered light as a result of interaction with red blood cells. It can be used to visualize perfusion in various tissues and, even though this technique has been extensively described in the literature, the actual clinical implementation lags behind. We provide an overview of LSCI as a tool to image tissue perfusion. We present a brief introduction to the theory, review clinical studies from various medical fields, and discuss current limitations impeding clinical acceptance.
Molecular image-guided surgery has the potential for translating the tools of molecular pathology to real-time guidance in surgery. As a whole, there are incredibly positive indicators of growth, including the first United States Food and Drug Administration clearance of an enzyme-biosynthetic-activated probe for surgery guidance, and a growing number of companies producing agents and imaging systems. The strengths and opportunities must be continued but are hampered by important weaknesses and threats within the field. A key issue to solve is the inability of macroscopic imaging tools to resolve microscopic biological disease heterogeneity and the limitations in microscopic systems matching surgery workflow. A related issue is that parsing out true molecular-specific uptake from simple-enhanced permeability and retention is hard and requires extensive pathologic analysis or multiple in vivo tests, comparing fluorescence accumulation with standard histopathology and immunohistochemistry. A related concern in the field is the over-reliance on a finite number of chosen preclinical models, leading to early clinical translation when the probe might not be optimized for high intertumor variation or intratumor heterogeneity. The ultimate potential may require multiple probes, as are used in molecular pathology, and a combination with ultrahigh-resolution imaging and image recognition systems, which capture the data at a finer granularity than is possible by the surgeon. Alternatively, one might choose a more generalized approach by developing the tracer based on generic hallmarks of cancer to create a more “one-size-fits-all” concept, similar to metabolic aberrations as exploited in fluorodeoxyglucose - positron emission tomography (FDG-PET) (i.e., Warburg effect) or tumor acidity. Finally, methods to approach the problem of production cost minimization and regulatory approvals in a manner consistent with the potential revenue of the field will be important. In this area, some solid steps have been demonstrated in the use of fluorescent labeling commercial antibodies and separately in microdosing studies with small molecules.
Maximilian Koch, Johannes de Jong, Jürgen Glatz, Panagiotis Symvoulidis, Laetitia Lamberts, Arthur L. L. Adams, Mariëtte E. G. Kranendonk, Anton G. T. Terwisscha van Scheltinga, Michaela Aichler, Liesbeth Jansen, Jakob de Vries, Marjolijn Lub-de Hooge, Carolien Schröder, Annelies Jorritsma-Smit, Matthijs Linssen, Esther de Boer, Bert van der Vegt, Wouter Nagengast, Sjoerd Elias, Sabrina Oliveira, Arjen Witkamp, Willem P. Th. M. Mali, Elsken Van der Wall, P. Beatriz Garcia-Allende, Paul van Diest, Elisabeth G. E. de Vries, Axel Walch, Gooitzen van Dam, Vasilis Ntziachristos
In-vivo fluorescently labelled drug (bevacizumab) breast cancer specimen where obtained from patients. We propose a new structured method to determine the optimal classification threshold in targeted fluorescence intra-operative imaging.
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.
In this work, we show, for the first time to our knowledge, that multispectral optoacoustic tomography (MSOT) can
deliver high resolution images of activatable molecular probe's distribution, sensitive to matrix metalloproteinases
(MMP), deep within optically scattering human carotid specimen. It is further demonstrated that this method can be used
in order to provide accurate maps of vulnerable plaque formations in atherosclerotic disease. Moreover, optoacoustic
images can simultaneously show the underlining plaque morphology for accurate localization of MMP activity in three
dimensions. This performance directly relates to small animal screening applications and to clinical potential as well.
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.
In gastrointestinal surgery, leakage of anastomoses in general is a challenging problem because of the related mortality and morbidity1,2. The highest incidence of anastomotic leakage is found at the most proximal and most distal parts of the digestive tract, i.e. esophageal and colorectal anastomoses. Increased strain and limited vascular supply at the anastomoses are the two main reasons of leakage, especially in the absence of a serosal layer at these sites2,3,4. Apart from these local risk factors, several general risk factors attributed to the occurrence of anastomotic failure, of which smoking, cardiovascular disease, gender, age and malnutrition are the most important2,5-8. Most of these factors suggest local ischemia as an important cause of anastomotic dehiscence. In esophageal resection the blood supply to the remaining esophageal end is compromised due to ligation of arteries and resection of surrounding mediastinal tissue. Furthermore, the gastric conduit, usually only based on the right gastroepiploic artery, is transposed from its anatomical abdominal position into the thoracic cavity and cervical region. Apart from co-existing morbidities such as sepsis, cardiovascular and several systemic diseases, the altered vascular supply frequently compromises the microcirculation at both ends of the anastomosis, and is as such responsible for the higher rate of leakage compared to small and other large bowel anastomoses9,10.
In gastrointestinal surgery, leakage of anastomoses in general is a challenging problem because of the related mortality and morbidity1,2. The highest incidence of anastomotic leakage is found at the most proximal and most distal parts of the digestive tract, i.e. esophageal and colorectal anastomoses. Increased strain and limited vascular supply at the anastomoses are the two main reasons of leakage, especially in the absence of a serosal layer at these sites2,3,4. Apart from these local risk factors, several general risk factors attributed to the occurrence of anastomotic failure, of which smoking, cardiovascular disease, gender, age and malnutrition are the most important2,5-8. Most of these factors suggest local ischemia as an important cause of anastomotic dehiscence. In colorectal anastomosis the vascular supply is compromised due to resection of the diseased bowel segment. The vascular supply of the rectal stump is compromised by resection of the proximal feeding sigmoidal vessels. Apart from co-existing morbidities such as sepsis, cardiovascular and several systemic diseases, the altered vascular supply frequently compromises the microcirculation at both ends of the anastomosis, and is as such responsible for the higher rate of leakage compared to small and other large bowel anastomoses9,10.
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