Optical innovations in surgery

Optical imaging guidance in oncologic surgery and interventional oncology

Over recent decades, optical imaging (OI) has become an integral part of medical imaging, offering significant advantages over other modalities, such as computed tomography (CT) and magnetic resonance imaging (MRI). OI is distinguished by its real-time imaging capability, cost-effectiveness, portability, absence of ionizing radiation, and high patient acceptability. The introduction of advanced optical dyes (including FDA-approved agents like indocyanine green, Cytalux, and Gleolan) has greatly enhanced its clinical utility. OI has shown clear benefits in the management of patients with cancer, originally by open surgery and now extending to minimally invasive, image-guided interventional procedures. This review highlights recent developments in OI for oncology, emphasizing its benefits for clinicians in guiding surgical and interventional procedures.

Intra-Operative Tumour Detection and Staging in Pancreatic Cancer Surgery: An Integrative Review of Current Standards and Future Directions

BACKGROUND

Surgical resection for pancreatic ductal adenocarcinoma (PDAC) entails the excision of the primary tumour and regional lymphadenectomy. This traditional strategy is challenged by the high rate of early recurrence, suggesting inadequate disease staging. Novel methods of intra-operative staging are needed to allow surgical resection to be tailored to the disease's biology.

METHODS

A search of published articles on the PubMed and Embase databases was performed using the terms 'pancreas' OR 'pancreatic' AND 'intra-operative staging/detection' OR 'guided surgery'. Articles published between January 2000 and June 2023 were included. Technologies that offered intra-operative staging and tailored treatment were curated and summarised in the following integrative review.

RESULTS

lymph node (LN) mapping and radioimmunoguided surgery have shown promising results but lacked practicality to facilitate real-time intra-operative staging for PDAC. Fluorescence-guided surgery (FGS) offers high contrast and sensitivity, enabling the identification of cancerous tissue and positive LNs with improved precision following intravenous administration of a fluorescent agent. The unique properties of optical coherence tomography and ultrasound elastography lend themselves to be platforms for virtual biopsy intra-operatively.

CONCLUSIONS

Accurate intra-operative staging of PDAC, localisation of metastatic LNs, and identification of extra-pancreatic disease remain clinically unmet needs under current detection methods and staging standards. Tumour-specific FGS combined with other diagnostic and therapeutic modalities could improve tumour detection and staging in patients with PDAC.

Recent advances of photoresponsive nanomaterials for diagnosis and treatment of acute kidney injury

Non-invasive imaging in the near-infrared region (NIR) offers enhanced tissue penetration, reduced spontaneous fluorescence of biological tissues, and improved signal-to-noise ratio (SNR), rendering it more suitable for in vivo deep tissue imaging. In recent years, a plethora of NIR photoresponsive materials have been employed for disease diagnosis, particularly acute kidney injury (AKI). These encompass inorganic nonmetallic materials such as carbon (C), silicon (Si), phosphorus (P), and upconversion nanoparticles (UCNPs); precious metal nanoparticles like gold and silver; as well as small molecule and organic semiconductor polymer nanoparticles with near infrared responsiveness. These materials enable effective therapy triggered by NIR light and serve as valuable tools for monitoring AKI in living systems. The review provides a concise overview of the current state and pathological characteristics of AKI, followed by an exploration of the application of nanomaterials and photoresponsive nanomaterials in AKI. Finally, it presents the design challenges and prospects associated with NIR photoresponsive materials in AKI.

Illuminating the future of precision cancer surgery with fluorescence imaging and artificial intelligence convergence

Real-time and accurate guidance for tumor resection has long been anticipated by surgeons. In the past decade, the flourishing material science has made impressive progress in near-infrared fluorophores that may fulfill this purpose. Fluorescence imaging-guided surgery shows great promise for clinical application and has undergone widespread evaluations, though it still requires continuous improvements to transition this technique from bench to bedside. Concurrently, the rapid progress of artificial intelligence (AI) has revolutionized medicine, aiding in the screening, diagnosis, and treatment of human doctors. Incorporating AI helps enhance fluorescence imaging and is poised to bring major innovations to surgical guidance, thereby realizing precision cancer surgery. This review provides an overview of the principles and clinical evaluations of fluorescence-guided surgery. Furthermore, recent endeavors to synergize AI with fluorescence imaging were presented, and the benefits of this interdisciplinary convergence were discussed. Finally, several implementation strategies to overcome technical hurdles were proposed to encourage and inspire future research to expedite the clinical application of these revolutionary technologies.

Infrared Fluorescence-guided Surgery for Tumor and Metastatic Lymph Node Detection in Head and Neck Cancer

In patients with head and neck cancer (HNC), surgical removal of cancerous tissue presents the best overall survival rate. However, failure to obtain negative margins during resection has remained a steady concern over the past 3 decades. The need for improved tumor removal and margin assessment presents an ongoing concern for the field. While near-infrared agents have long been used in imaging, investigation of these agents for use in HNC imaging has dramatically expanded in the past decade. Targeted tracers for use in primary and metastatic lymph node detection are of particular interest, with panitumumab-IRDye800 as a major candidate in current studies. This review aims to provide an overview of intraoperative near-infrared fluorescence-guided surgery techniques used in the clinical detection of malignant tissue and sentinel lymph nodes in HNC, highlighting current applications, limitations, and future directions for use of this technology within the field. Keywords: Molecular Imaging-Cancer, Fluorescence © RSNA, 2024.

Blood Flow in the Meniscus Can Be Visualized Arthroscopically Using an Intravenous Indocyanine Green Solution Diluted 10× in a Pig Model

Purpose

To determine the optimal indocyanine green (ICG) dose required for assessing vascularity in the meniscus using ICG fluorescence-guided knee arthroscopy in a pig model.

Methods

A 3-month-old Japanese esculent female pig was used in this study. Intravenous injections of ICG (25 mg) were administered with 2.0 mL of 5×, 10×, 100×, and 1,000× diluted solutions. An additional experiment was conducted to assess the microvasculature within the meniscus considering the results of the optimal dilution setting. A radial tear was purposely induced in the middle-to-posterior section of the medial meniscus to observe vascularity in the cross-sectioned meniscus; the optimal ICG dilution was administered.

Results

No fluorescence was detected in the meniscus with solutions diluted by 1,000× and 100×. Fluorescence was visualized at the anterior portion of the synovium and the anterior cruciate ligament using ICG diluted by 10×. Diluting ICG by 5×, contrast enhancement was too intense for observation. Therefore, the 10× diluted solution was considered the optimal setting for knee arthroscopy and observation of the radial tear. No fluorescence was observed in the cross section of the medial meniscus. Arterial hemorrhage was observed by stimulating the fluorescence-dyed synovium adjacent to the tear site. Through the additional waiting time after stimulating the tear site, the hemorrhage inside the meniscus became more intense.

Conclusions

The optimal dilution and dose setting of ICG for knee arthroscopy was 10× in a 2.0-mL intravenous injection. The meniscus showed no active blood flow, even in the red-red zone. This finding might support the notion that blood flow cannot be initiated, without synovial stimulation, even in vascular areas.

Clinical Relevance

This study could determine an ICG solution suitable for ICG fluorescence-guided knee arthroscopy. This finding could be valuable in future research focusing on case-specific meniscal vascularization under arthroscopy, particularly applying these findings to human meniscal treatment.

Novel Near-Infrared-II In Vivo Visualization Revealed Rapid Calcium Intestine Turnover in Daphnia magna with Delayed Impact by Cadmium and Acidification

Calcium is a highly demanded metal, and its transport across the intestine of Daphnia magna remains a significant unresolved question. Due to technical constraints, the visualization of the kinetic process of Ca passage through D. magna has been challenging. Here, we developed the second near-infrared Ca sensor (NIR-II Ca) and conducted real-time in vivo imaging of Ca in daphnids with a high signal-to-noise ratio, deep tissue penetration, and minimal damage. Through the utilization of the NIR-II Ca sensor, we for the first time visualized and quantified the kinetic process of Ca passage in the intestine in real time. The results revealed that trophically available Ca passed through the intestines in 24 h, whereas waterborne Ca required only 35 min. This rapid "flushing through" mechanism established waterborne Ca as the primary source of Ca absorption. However, environmental stressors such as water acidification and cadmium significantly delayed the Ca passage and absorption. The development of NIR imaging and sensors allows for real-time dynamic visualization of contaminants/nutrients in organisms and holds great potential as a powerful tool for future studies into material kinetic processes in living animals.

3D Specimen Scanning and Mapping in Musculoskeletal Oncology: A Feasibility Study

BACKGROUND

Surgical resection is the primary treatment for bone and soft tissue tumors. Negative margin status is a key factor in prognosis. Given the three-dimensional (3D) anatomic complexity of musculoskeletal tumor specimens, communication of margin results between surgeons and pathologists is challenging. We sought to perform ex vivo 3D scanning of musculoskeletal oncology specimens to enhance communication between surgeons and pathologists.

METHODS

Immediately after surgical resection, 3D scanning of the fresh specimen is performed prior to frozen section analysis. During pathologic grossing, whether frozen or permanent, margin sampling sites are annotated on the virtual 3D model using computer-aided design (CAD) software.

RESULTS

3D scanning was performed in seven cases (six soft tissue, one bone), with specimen mapping on six cases. Intraoperative 3D scanning and mapping was performed in one case in which the location of margin sampling was shown virtually in real-time to the operating surgeon to help achieve a negative margin. In six cases, the 3D model was used to communicate final permanent section analysis. Soft tissue, cartilage, and bone (including lytic lesions within bone) showed acceptable resolution.

CONCLUSIONS

Virtual 3D scanning and specimen mapping is feasible and may allow for enhanced documentation and communication. This protocol provides useful information for anatomically complex musculoskeletal tumor specimens. Future studies will evaluate the effect of the protocol on positive margin rates, likelihood that a re-resection contains additional malignancy, and exploration of targeted adjuvant radiation protocols using a patient-specific 3D specimen map.

Enhancing visualization and guidance in general surgery: a comprehensive and narrative review of the current cutting-edge technologies and future perspectives

BACKGROUND

In the last decade, there has been a great effort in developing new technologies to enhance surgical visualization and guidance. This comprehensive and narrative review aimed to provide a wide and extensive overview of the current state of the art on this topic and their near-future perspectives linked to the development of artificial intelligence (AI), by focusing on the most recent and relevant literature.

METHODS

A comprehensive and narrative review of the literature was performed by searching specific terms on PubMed/MEDLINE, Scopus, and Embase databases, assessing the current state of the art on this topic.

RESULTS

Fluorescence-guided surgery, contrast-enhanced ultrasound (CEUS), ultra-high frequency ultrasound (UHFUS), photoacoustic imaging (PAI), and augmented reality (AR) are boosting the field of image-guided techniques as the rapid development of AI in surgery is promising a more automated decision-making and surgical movements in the operating room.

CONCLUSION

Fluorescence-guided surgery, CEUS, UHFUS, PAI, and AR are becoming crucial to give surgeons a new level of information during the intervention, with the right timing and sequence, and represent the future of surgery. As many more controlled studies are needed to validate the employment of these technologies, the next generation of surgeons must become more familiar with the basics of AI to better incorporate new tools into the daily surgical practice of the future.

Dynamic interaction of injected liquid jet with skin layer interfaces revealed by microsecond imaging of optically cleared ex vivo skin tissue model

BACKGROUND

Needle-free jet injection (NFJI) systems enable a controlled and targeted delivery of drugs into skin tissue. However, a scarce understanding of their underlying mechanisms has been a major deterrent to the development of an efficient system. Primarily, the lack of a suitable visualization technique that could capture the dynamics of the injected fluid-tissue interaction with a microsecond range temporal resolution has emerged as a main limitation. A conventional needle-free injection system may inject the fluids within a few milliseconds and may need a temporal resolution in the microsecond range for obtaining the required images. However, the presently available imaging techniques for skin tissue visualization fail to achieve these required spatial and temporal resolutions. Previous studies on injected fluid-tissue interaction dynamics were conducted using in vitro media with a stiffness similar to that of skin tissue. However, these media are poor substitutes for real skin tissue, and the need for an imaging technique having ex vivo or in vivo imaging capability has been echoed in the previous reports.

METHODS

A near-infrared imaging technique that utilizes the optical absorption and fluorescence emission of indocyanine green dye, coupled with a tissue clearing technique, was developed for visualizing a NFJI in an ex vivo porcine skin tissue.

RESULTS

The optimal imaging conditions obtained by considering the optical properties of the developed system and mechanical properties of the cleared ex vivo samples are presented. Crucial information on the dynamic interaction of the injected liquid jet with the ex vivo skin tissue layers and their interfaces could be obtained.

CONCLUSIONS

The reported technique can be instrumental for understanding the injection mechanism and for the development of an efficient transdermal NFJI system as well.

Near-Infrared Spectral Similarity between Ex Vivo Porcine and In Vivo Human Tissue

BACKGROUND

In vivo diffuse reflectance spectroscopy provides additional contrast in discriminating nerves embedded in adipose tissue during surgery. However, large datasets are required to achieve clinically acceptable classification levels. This study assesses the spectral similarity between ex vivo porcine and in vivo human spectral data of nerve and adipose tissue, as porcine tissue could contribute to generate large datasets.

METHODS

Porcine diffuse reflectance spectra were measured at 124 nerve and 151 adipose locations. A previously recorded dataset of 32 in vivo human nerve and 23 adipose tissue locations was used for comparison. In total, 36 features were extracted from the raw porcine to generate binary logistic regression models for all combinations of two, three, four and five features. Feature selection was performed by assessing similar means between normalized features of nerve and of adipose tissue (Kruskal-Wallis test, p < 0.05) and for models performing best on the porcine cross validation set. The human test set was used to assess classification performance.

RESULTS

The binary logistic regression models with selected features showed an accuracy of 60% on the test set.

CONCLUSIONS

Spectral similarity between ex vivo porcine and in vivo human adipose and nerve tissue was present, but further research is required.

A c-MET-Targeted Topical Fluorescent Probe cMBP-ICG Improves Oral Squamous Cell Carcinoma Detection in Humans

INTRODUCTION

The postoperative survival of oral squamous cell carcinoma (SCC) relies on precise detection and complete resection of original tumors. The mucosal extension of the tumor is evaluated visually during surgery, but small and flat foci are difficult to detect. Real-time fluorescence imaging may improve detection of tumor margins.

MATERIALS AND METHODS

In the current study, a peptide-based near-infrared (NIR) fluorescence dye, c-MET-binding peptide-indocyanine green (cMBP-ICG), which specifically targets tumor via c-MET binding, was synthetized. A prospective pilot clinical trial then was conducted with oral SCC patients and intraoperatively to assess the feasibility of cMBP-ICG used to detect tumors margins. Fluorescence was histologically correlated to determine sensitivity and specificity.

RESULTS

The immunohistochemistry (IHC) results demonstrated increased c-Met expression in oral SCC compared with normal mucosa. Tumor-to-background ratios ranged from 2.71 ± 0.7 to 3.11 ± 1.2 in different concentration groups. From 10 patients with oral SCC, 60 specimens were collected from tumor margins. The sensitivity and specificity of discriminative value derived from cMBP-ICG application in humans were respectively 100% and 75%.

CONCLUSIONS

Topical application of cMBP-ICG is feasible and safe for optimizing intraoperative visualization and tumor margin detection in oral SCC patients, which could clinically increase the probability of complete resections and improve oncologic outcomes.

Near-infrared fluorescent imaging techniques for the detection and preservation of parathyroid glands during endocrine surgery

Objectives

In over 30% of all thyroid surgeries, complications arise from transient and definitive hypoparathyroidism, underscoring the need for real-time identification and preservation of parathyroid glands (PGs). Here, we evaluate the promising intraoperative optical technologies available for the identification, preservation, and functional assessment of PGs to enhance endocrine surgery.

Methods

We performed a review of the literature to identify published studies on fluorescence imaging in thyroid and parathyroid surgery.

Results

Fluorescence imaging is a well-demonstrated approach for both in vivo and in vitro localization of specific cells or tissues, and is gaining popularity as a technique to detect PGs during endocrine surgery. Autofluorescence (AF) imaging and indocyanine green (ICG) angiography are two emerging optical techniques to improve outcomes in thyroid and parathyroid surgeries. Near-infrared-guided technology has significantly contributed to the localization of PGs, through the detection of glandular AF. Perfusion through the PGs can be visualized with ICG, which can also reveal the blood supply after dissection.

Conclusions

Near infrared AF and ICG angiography, providing a valuable spatial and anatomical information, can decrease the incidence of complications in thyroid surgery.

Quantitative tumor depth determination using dual wavelength excitation fluorescence

Quantifying solid tumor margins with fluorescence-guided surgery approaches is a challenge, particularly when using near infrared (NIR) wavelengths due to increased penetration depths. An NIR dual wavelength excitation fluorescence (DWEF) approach was developed that capitalizes on the wavelength-dependent attenuation of light in tissue to determine fluorophore depth. A portable dual wavelength excitation fluorescence imaging system was built and tested in parallel with an NIR tumor-targeting fluorophore in tissue mimicking phantoms, chicken tissue, and in vivo mouse models of breast cancer. The system showed high accuracy in all experiments. The low cost and simplicity of this approach make it ideal for clinical use.

Indocyanine Green Endoscopy for Pituitary Adenomas with Parasellar Extension: Results from a Preliminary Case Series

BACKGROUND

Advances in visualization tools have brought new confidence, including endoscope-integrated indocyanine (E-ICG), which makes pituitary and skull-base surgery safer and more effective. We report here our preliminary experience with the use of E-ICG to 1) visualize the cavernous segment of the internal carotid artery (ICA); and 2) functionally and anatomically preserve the pituitary gland.

METHODS

A dedicated ICG-integrated endoscope was used in 15 patients with parasellar pituitary adenomas. Indocyanine was administered at 2 different time points during surgery: an early bolus of 12.5 mg at the sphenoid sinus opening to expose the position of the parasellar segment of the ICAs and to identify the position of the normal pituitary gland so that it could be preserved during tumor removal. Subsequently, a second late bolus of 12 mg of ICG was injected to obtain a real-time "wire angiographic" visualization of the flow of the ICAs.

RESULTS

Gross total resection was achieved in 12 cases (80%), whereas subtotal resection was performed in the other 3 cases (20%). The pituitary gland was clearly discernable in 11 cases (91.6%). None of the patients manifested new endocrinologic deficits or major vascular complications.

CONCLUSIONS

E-ICG is a safe and essential aid for pituitary adenomas invading the cavernous sinus. Its performance as a pituitary marker and real-time video angiography showed promising results in terms of extent of resection, endocrinologic outcomes, and prevention of intraoperative complications.

The current status and future prospects for molecular imaging-guided precision surgery

Molecular imaging technologies are increasingly used to diagnose, monitor, and guide treatment of i.e., cancer. In this review, the current status and future prospects of the use of molecular imaging as an instrument to help realize precision surgery is addressed with focus on the main components that form the conceptual basis of intraoperative molecular imaging. Paramount for successful interventions is the relevance and accessibility of surgical targets. In addition, selection of the correct combination of imaging agents and modalities is critical to visualize both microscopic and bulk disease sites with high affinity and specificity. In this context developments within engineering/imaging physics continue to drive the growth of image-guided surgery. Particularly important herein is enhancement of sensitivity through improved contrast and spatial resolution, features that are critical if sites of cancer involvement are not to be overlooked during surgery. By facilitating the connection between surgical planning and surgical execution, digital surgery technologies such as computer-aided visualization nicely complement these technologies. The complexity of image guidance, combined with the plurality of technologies that are becoming available, also drives the need for evaluation mechanisms that can objectively score the impact that technologies exert on the performance of healthcare professionals and outcome improvement for patients.

Topical pH Sensing NIR Fluorophores for Intraoperative Imaging and Surgery of Disseminated Ovarian Cancer

Fluorescence-guided surgery (FGS) aids surgeons with real-time visualization of small cancer foci and borders, which improves surgical and prognostic efficacy of cancer. Despite the steady advances in imaging devices, there is a scarcity of fluorophores available to achieve optimal FGS. Here, 1) a pH-sensitive near-infrared fluorophore that exhibits rapid signal changes in acidic tumor microenvironments (TME) caused by the attenuation of intramolecular quenching, 2) the inherent targeting for cancer based on chemical structure (structure inherent targeting, SIT), and 3) mitochondrial and lysosomal retention are reported. After topical application of PH08 on peritoneal tumor regions in ovarian cancer-bearing mice, a rapid fluorescence increase (< 10 min), and extended preservation of signals (> 4 h post-topical application) are observed, which together allow for the visualization of submillimeter tumors with a high tumor-to-background ratio (TBR > 5.0). In addition, PH08 is preferentially transported to cancer cells via organic anion transporter peptides (OATPs) and colocalizes in the mitochondria and lysosomes due to the positive charges, enabling a long retention time during FGS. PH08 not only has a significant impact on surgical and diagnostic applications but also provides an effective and scalable strategy to design therapeutic agents for a wide array of cancers.

The complementary value of intraoperative fluorescence imaging and Raman spectroscopy for cancer surgery: combining the incompatibles

A clear margin is an important prognostic factor for most solid tumours treated by surgery. Intraoperative fluorescence imaging using exogenous tumour-specific fluorescent agents has shown particular benefit in improving complete resection of tumour tissue. However, signal processing for fluorescence imaging is complex, and fluorescence signal intensity does not always perfectly correlate with tumour location. Raman spectroscopy has the capacity to accurately differentiate between malignant and healthy tissue based on their molecular composition. In Raman spectroscopy, specificity is uniquely high, but signal intensity is weak and Raman measurements are mainly performed in a point-wise manner on microscopic tissue volumes, making whole-field assessment temporally unfeasible. In this review, we describe the state-of-the-art of both optical techniques, paying special attention to the combined intraoperative application of fluorescence imaging and Raman spectroscopy in current clinical research. We demonstrate how these techniques are complementary and address the technical challenges that have traditionally led them to be considered mutually exclusive for clinical implementation. Finally, we present a novel strategy that exploits the optimal characteristics of both modalities to facilitate resection with clear surgical margins.

Fluorescence-guided detection of pituitary neuroendocrine tumor (PitNET) tissue during endoscopic transsphenoidal surgery available agents, their potential, and technical aspects

Differentiation of pituitary neuroendocrine tumor (PitNET) tissue from surrounding normal tissue during surgery is challenging. A number of fluorescent agents is available for visualization of tissue discrepancy, with the potential of improving total tumor resection. This review evaluates the availability, clinical and technical applicability of the various fluorescent agents within the field of pituitary surgery. According to PRISMA guidelines, a systematic review was performed to identify reports describing results of in vivo application of fluorescent agents. In this review, 15 publications were included. Sodium Fluorescein (FNa) was considered in two studies. The first study reported noticeable fluorescence in adenoma tissue, the second demonstrated the strongest fluorescence in non-functioning pituitary adenomas. 5-Aminolevulinic acid (5-ALA) was investigated in three studies. One study compared laser-based optical biopsy system (OBS) with photo-diagnostic filter (PD) and found that the OBS was able to detect all microadenomas, even when MRI was negative. The second study retrospectively analyzed twelve pituitary adenomas and found only one positive for fluorescence. The third investigated fifteen pituitary adenomas of which one displayed vague fluorescence. Indocyanine green (ICG) was researched in four studies with variable results. Second-Window ICG yielded no significant difference between functioning and non-functioning adenomas in one study, while a second study displayed 4 times higher fluorescence in tumor tissue than in normal tissue. In three studies, OTL38 showed potential in non-functioning pituitary adenomas. At present, evidence for fluorescent agents to benefit total resection of PitNETs is lacking. OTL38 can potentially serve as a selective fluorescent agent in non-functioning pituitary adenomas in the near future.

3D Reconstruction of cellular images from microfabricated imagers using fully-adaptive deep neural networks

Millimeter-scale multi-cellular level imagers enable various applications, ranging from intraoperative surgical navigation to implantable sensors. However, the tradeoffs for miniaturization compromise resolution, making extracting 3D cell locations challenging—critical for tumor margin assessment and therapy monitoring. This work presents three machine-learning-based modules that extract spatial information from single image acquisitions using custom-made millimeter-scale imagers. The neural networks were trained on synthetically-generated (using Perlin noise) cell images. The first network is a convolutional neural network estimating the depth of a single layer of cells, the second is a deblurring module correcting for the point spread function (PSF). The final module extracts spatial information from a single image acquisition of a 3D specimen and reconstructs cross-sections, by providing a layered “map” of cell locations. The maximum depth error of the first module is 100 µm, with 87% test accuracy. The second module’s PSF correction achieves a least-square-error of only 4%. The third module generates a binary “cell” or “no cell” per-pixel labeling with an accuracy ranging from 89% to 85%. This work demonstrates the synergy between ultra-small silicon-based imagers that enable in vivo imaging but face a trade-off in spatial resolution, and the processing power of neural networks to achieve enhancements beyond conventional linear optimization techniques.

Intraoperative imaging in pathology-assisted surgery

The pathological assessment of surgical specimens during surgery can reduce the incidence of positive resection margins, which otherwise can result in additional surgeries or aggressive therapeutic regimens. To improve patient outcomes, intraoperative spectroscopic, fluorescence-based, structural, optoacoustic and radiological imaging techniques are being tested on freshly excised tissue. The specific clinical setting and tumour type largely determine whether endogenous or exogenous contrast is to be detected and whether the tumour specificity of the detected biomarker, image resolution, image-acquisition times or penetration depth are to be prioritized. In this Perspective, we describe current clinical standards for intraoperative tissue analysis and discuss how intraoperative imaging is being implemented. We also discuss potential implementations of intraoperative pathology-assisted surgery for clinical decision-making.

Fast and Durable Intraoperative Near-infrared Imaging of Ovarian Cancer Using Ultrabright Squaraine Fluorophores

The residual tumor after surgery is the most significant prognostic factor of patients with epithelial ovarian cancer. Near-infrared (NIR) fluorescence-guided surgery is actively utilized for tumor localization and complete resection during surgery. However, currently available contrast-enhancing agents display low on-target binding, unfavorable pharmacokinetics, and toxicity, thus not ideal for clinical use. Here we report ultrabright and stable squaraine fluorophores with optimal pharmacokinetics by introducing an asymmetric molecular conformation and surface charges for rapid transporter-mediated cellular uptake. Among the tested, OCTL14 shows low serum binding and rapid distribution into cancer tissue via organic cation transporters (OCTs). Additionally, the charged squaraine fluorophores are retained in lysosomes, providing durable intraoperative imaging in a preclinical murine model of ovarian cancer up to 24 h post-injection. OCTL14 represents a significant departure from the current bioconjugation approach of using a non-targeted fluorophore and would provide surgeons with an indispensable tool to achieve optimal resection.

Recent Technical Advances in Accelerating the Clinical Translation of Small Animal Brain Imaging: Hybrid Imaging, Deep Learning, and Transcriptomics

Small animal models play a fundamental role in brain research by deepening the understanding of the physiological functions and mechanisms underlying brain disorders and are thus essential in the development of therapeutic and diagnostic imaging tracers targeting the central nervous system. Advances in structural, functional, and molecular imaging using MRI, PET, fluorescence imaging, and optoacoustic imaging have enabled the interrogation of the rodent brain across a large temporal and spatial resolution scale in a non-invasively manner. However, there are still several major gaps in translating from preclinical brain imaging to the clinical setting. The hindering factors include the following: (1) intrinsic differences between biological species regarding brain size, cell type, protein expression level, and metabolism level and (2) imaging technical barriers regarding the interpretation of image contrast and limited spatiotemporal resolution. To mitigate these factors, single-cell transcriptomics and measures to identify the cellular source of PET tracers have been developed. Meanwhile, hybrid imaging techniques that provide highly complementary anatomical and molecular information are emerging. Furthermore, deep learning-based image analysis has been developed to enhance the quantification and optimization of the imaging protocol. In this mini-review, we summarize the recent developments in small animal neuroimaging toward improved translational power, with a focus on technical improvement including hybrid imaging, data processing, transcriptomics, awake animal imaging, and on-chip pharmacokinetics. We also discuss outstanding challenges in standardization and considerations toward increasing translational power and propose future outlooks.

Methods to Measure the Inhibition of ABCG2 Transporter and Ferrochelatase Activity to Enhance Aminolevulinic Acid-Protoporphyrin IX Fluorescence-Guided Tumor Detection and Resection

Aminolevulinic acid (ALA) has been clinically used as an intraoperative fluorescence probe for protoporphyrin IX (PpIX) fluorescence-guided tumor resection and a PDT agent for cancer treatment. Although tumor tissues often show increased ALA-PpIX fluorescence compared with normal tissues, which enables the use of ALA for tumor imaging and targeting, weak tumor PpIX fluorescence as well as the heterogeneity in tumor fluorescence severely limits its clinical application. Intracellular PpIX in tumor cells is reduced by two major mechanisms, efflux by ATP-binding cassette (ABC) transporters such as ABCG2 and bioconversion to form heme by ferrochelatase (FECH) in the heme biosynthesis pathway. Targeting these two predominant PpIX-reducing mechanisms for the enhancement of ALA-PpIX have yielded a plethora of promising results and stimulated the clinical exploration of these enhancement strategies. Here we describe our methods of evaluating chemicals for the inhibition of ABCG2 transporter and FECH activity. Our goal is to further encourage research and development of novel ABCG2 and FECH inhibitors and promote a rational use of these inhibitors to optimize ALA-based tumor detection and treatment.

Sensing Reactive Oxygen Species with Photoacoustic Imaging Using Conjugation-Extended BODIPYs

Short-lived reactive intermediates such as reactive oxygen species (ROS) regulate many physiological processes, but overproduction can also lead to severe tissue dysfunction. Thus, there is a high demand for noninvasive detection of reactive molecules, which, however, is challenging. Herein, we report photoacoustic detection of ROS using conjugated BODIPY probes (ROS-BODIPYs). The ROS reaction with conjugated BODIPYs induced a redshift in absorption by ∼100 nm into the near infrared (from ∼700 to ∼800 nm), quenched fluorescence, and generated strong photoacoustic (PA) signals. Thus, the ROS-activated and ROS-nonactivated states of ROS-BODIPYs can be detected in vivo by PA and fluorescence imaging. Interestingly, ROS activation is reversible, in the presence of excess reducing agents, e.g., citric acid, converted back to its original state, suggesting that ROS-BODIPYs can be useful for the detection of over production of ROS but not physiological amounts. This makes the imaging independent of accumulation of the activated probe with the physiological ROS amounts and thus strongly improves applicability and highlights the translational potential of ROS-BODIPYs for detecting overexpression of ROS in vivo by optical and photoacoustic imaging methods.

Above and Beyond Robotic Surgery and 3D Modelling in Paediatric Cancer Surgery

Although the survival rates for children's cancers have more than doubled in the last few decades, the surgical practise has not significantly changed. Among the most recent innovations introduced in the clinic, robotic surgery and augmented reality are two of the most promising, even if they are not widespread. The increased flexibility of the motion, the magnification of the surgical field and the tremor reduction provided by robotic surgery have been beneficial to perform complex oncological procedures in children. Besides, augmented reality has been proven helpful in planning for tumour removal, facilitating early discrimination between cancer and healthy organs. Nowadays, research in the field of surgical oncology is moving fast, and new technologies and innovations wich will help to shape a new way to perform cancer surgery. Paediatric surgeons need to be ready to adopt these novel devices and intraoperative techniques to allow more radical tumour resections with fewer complications. This review aims to present the mechanism of action and indications of several novel technologies such as optical imaging surgery, high definition cameras, and intraoperative loco-regional treatments. We hope this will enhance early adoption and more research on how to employ technology for the benefit of children.

Antibody-functionalized theranostic protein nanoparticles for the synergistic deep red fluorescence imaging and multimodal therapy of ovarian cancer

Among women, ovarian cancer is the fifth most frequent type of cancer, and despite benefiting from current standard treatment plans, 90% of patients relapse in the subsequent 18 months and, eventually, perish. As a result, via embracing nanotechnological advancements in the field of medical science, researchers working in the areas of cancer therapy and imaging are looking for the next breakthrough treatment strategy to ensure lower cancer recurrence rates and improved outcomes for patients. Herein, we design a novel phototheranostic agent with optical features in the biological window of the electromagnetic spectrum via encapsulating a newly synthesized phthalocyanine dye within biocompatible protein nanoparticles, allowing the targeted fluorescence imaging and synergistic dual therapy of ovarian cancer. The nanosized agent displays great biocompatibility and enhanced aqueous biostability and photothermal activity, as well as high reactive-oxygen-species generation efficiency. To achieve the active targeting of the desired malignant tissue and suppress the rapid clearance of the photosensitive agent from the peritoneal cavity, the nanoparticles are biofunctionalized with an anti-folate receptor antibody. A2780 ovarian cancer cells are employed to confirm the improved targeting capabilities and the in vitro cytotoxic efficiency of the theranostic nanoparticles after exposure to a 660 nm LED lamp; upon measurement via MTT and flow cytometry assays, a significant 95% decrease in the total number of viable cells is seen. Additionally, the therapeutic performance of our newly designed nanoparticles was evaluated in vivo, via real-time thermal monitoring and histopathological assays, upon the irradiation of tumour-bearing mice with a 660 nm LED lamp (0.05 W cm-2). Foremost, separately from steady-state fluorescence imaging, we found that, via utilizing FLIM investigations, the differences in fluorescence lifetimes of antibody biofunctionalized and non-functionalized nanoparticles can be correlated to different intracellular localization and internalization pathways of the fluorescent agent, which is relevant for the development of a cutting-edge method for the detection of cancer cells that overexpress folate receptors at their surfaces.

Fluorescence Image-Guided Surgery for Thyroid Cancer: Utility for Preventing Hypoparathyroidism

Background: Hypoparathyroidism is one of the most frequent complications of thyroid surgery, especially when associated with lymph node dissection in cases of thyroid cancer. Fluorescence-guided surgery is an emerging tool that appears to help reduce the rate of this complication. The present review aims to highlight the utility of fluorescence imaging in preserving parathyroid glands during thyroid cancer surgery. Methods: We performed a systematic review of the literature according to PRISMA guidelines to identify published studies on fluorescence-guided thyroid surgery with a particular focus on thyroid cancer. Articles were selected and analyzed per indication and type of surgery, autofluorescence or exogenous dye usage, and outcomes. The Methodological Index for Non-Randomized Studies (MINORS) was used to assess the methodological quality of the included articles. Results: Twenty-five studies met the inclusion criteria, with three studies exclusively assessing patients with thyroid cancer. The remaining studies assessed mixed cohorts with thyroid cancer and other thyroid or parathyroid diseases. The majority of the papers support the potential benefit of fluorescence imaging in preserving parathyroid glands in thyroid surgery. Conclusions: Fluorescence-guided surgery is useful in the prevention of post-thyroidectomy hypoparathyroidism via enhanced early identification, visualization, and preservation of the parathyroid glands. These aspects are notably beneficial in cases of associated lymphadenectomy for thyroid cancer.

Design of a Near Infrared Fluorescent Ureter Imaging Agent for Prevention of Ureter Damage during Abdominal Surgeries

The inadvertent severing of a ureter during surgery occurs in as many as 4.5% of colorectal surgeries. To help prevent this issue, several near-infrared (NIR) dyes have been developed to assist surgeons with identifying ureter location. However, the majority of these dyes exhibit at least some issue that precludes their widespread usage such as high levels of uptake in other tissues, overlapping emission wavelengths with other NIR dyes used for other fluorescence-guided surgeries, and/or rapid excretion times through the ureters. To overcome these limitations, we have synthesized and characterized the spectral properties and biodistribution of a new series of PEGylated UreterGlow derivatives. The most promising dye, UreterGlow-11 was shown to almost exclusively excrete through the kidneys/ureters with detectable fluorescence observed for at least 12 h. Additionally, while the excitation wavelength is similar to that of other NIR dyes used for cancer resections, the emission is shifted by ~30 nm allowing for discrimination between the different fluorescence-guided surgery probes. In conclusion, these new UreterGlow dyes show promising optical and biodistribution characteristics and are good candidates for translation into the clinic.

Mesoscopic fluorescence lifetime imaging: Fundamental principles, clinical applications and future directions

Fluorescence lifetime imaging (FLIm) is an optical spectroscopic imaging technique capable of real-time assessments of tissue properties in clinical settings. Label-free FLIm is sensitive to changes in tissue structure and biochemistry resulting from pathological conditions, thus providing optical contrast to identify and monitor the progression of disease. Technical and methodological advances over the last two decades have enabled the development of FLIm instrumentation for real-time, in situ, mesoscopic imaging compatible with standard clinical workflows. Herein, we review the fundamental working principles of mesoscopic FLIm, discuss the technical characteristics of current clinical FLIm instrumentation, highlight the most commonly used analytical methods to interpret fluorescence lifetime data and discuss the recent applications of FLIm in surgical oncology and cardiovascular diagnostics. Finally, we conclude with an outlook on the future directions of clinical FLIm.

Importance of lymph node immune responses in MSI-H/dMMR colorectal cancer

Patients with colorectal cancers (CRCs) generally exhibit improved survival through intensive lymph node (LN) dissection. However, recent progress in cancer immunotherapy revisits the potential importance of regional LNs, where T cells are primed to attack tumor cells. To elucidate the role of regional LN, we investigated the immunological status of nonmetastatic regional LN lymphocytes (LNLs) in comparison with those of the tumor microenvironment (tumor-infiltrating lymphocytes; TILs) using flow cytometry and next-generation sequencing. LNLs comprised an intermediate level of the effector T cell population between peripheral blood lymphocytes (PBLs) and TILs. Significant overlap of the T cell receptor (TCR) repertoire was observed in microsatellite instability–high/mismatch repair–deficient (MSI-H/dMMR) CRCs with high tumor mutation burden (TMB), although limited TCRs were shared between nonmetastatic LNs and primary tumors in microsatellite stable/MMR proficient (MSS/pMMR) CRC patients with low TMB. In line with the overlap of the TCR repertoire, an excessive LN dissection did not provide a positive impact on long-term prognosis in our MSI-H/dMMR CRC cohort (n = 130). We propose that regional LNs play an important role in antitumor immunity, particularly in MSI-H/dMMR CRCs with high TMB, requiring care to be taken regarding excessive nonmetastatic LN dissection in MSI-H/dMMR CRC patients.

Novel imaging techniques for intraoperative margin assessment in surgical oncology: A systematic review

Inadequate margins continue to occur frequently in patients who undergo surgical resection of a tumor, suggesting that current intraoperative methods are not sufficiently reliable in determining the margin status. This clinical demand has inspired the development of many novel imaging techniques that could help surgeons with intraoperative margin assessment. This systematic review provides an overview of novel imaging techniques for intraoperative margin assessment in surgical oncology, and reports on their technical properties, feasibility in clinical practice and diagnostic accuracy. PubMed, Embase, Web of Science and the Cochrane library were systematically searched (2013‐2018) for studies reporting on imaging techniques for intraoperative margin assessment. Patient and study characteristics, technical properties, feasibility characteristics and diagnostic accuracy were extracted. This systematic review identified 134 studies that investigated and developed 16 groups of techniques for intraoperative margin assessment: fluorescence, advanced microscopy, ultrasound, specimen radiography, optical coherence tomography, magnetic resonance imaging, elastic scattering spectroscopy, bio‐impedance, X‐ray computed tomography, mass spectrometry, Raman spectroscopy, nuclear medicine imaging, terahertz imaging, photoacoustic imaging, hyperspectral imaging and pH measurement. Most studies were in early developmental stages (IDEAL 1 or 2a, n = 98); high‐quality stage 2b and 3 studies were rare. None of the techniques was found to be clearly superior in demonstrating high feasibility as well as high diagnostic accuracy. In conclusion, the field of imaging techniques for intraoperative margin assessment is highly evolving. This review provides a unique overview of the opportunities and limitations of the currently available imaging techniques.

What's new?

While surgical resection is critical in the treatment of primary solid tumors, resection at tumor margins remains problematic, with inadequately resected margins facilitating tumor recurrence. In this systematic review, the authors collected information on novel imaging techniques applied to the intraoperative assessment of tumor margins across cancer types. A total of 16 groups of techniques were identified, with many in early stages of clinical application. Following comparison, no single technique was clearly superior in clinical feasibility or diagnostic accuracy. The review highlights the evolving nature of imaging techniques for intraoperative margin assessment and identifies opportunities and limitations in the field.

Interventional NIR Fluorescence Imaging of Cancer: Review on Next Generation of Dye-Loaded Protein-Based Nanoparticles for Real-Time Feedback During Cancer Surgery

The use of fluorescence imaging technique for visualization, resection and treatment of cancerous tissue, attained plenty of interest once the promise of whole body and deep tissue near-infrared (NIR) imaging emerged. Why is NIR so desired? Contrast agents with optical properties in the NIR spectral range offer an upgrade for the diagnosis and treatment of cancer, by dint of the deep tissue penetration of light in the NIR region of the electromagnetic spectrum, also known as the optical window in biological tissue. Thus, the development of a new generation of NIR emitting and absorbing contrast agents able to overcome the shortcomings of the basic free dye administration is absolutely essential. Several examples of nanoparticles (NPs) have been successfully implemented as carriers for NIR dye molecules to the tumour site owing to their prolonged blood circulation time and enhanced accumulation within the tumour, as well as their increased fluorescence signal relative to free fluorophore emission and active targeting of cancerous cells. Due to their versatile structure, good biocompatibility and capability to efficiently load dyes and bioconjugate with diverse cancer-targeting ligands, the research area of developing protein-based NPs encapsulated or conjugated with NIR dyes is highly promising but still in its infancy. The current review aims to provide an up-to-date overview on the biocompatibility, specific targeting and versatility offered by protein-based NPs loaded with different classes of NIR dyes as next-generation fluorescent agents. Moreover, this study brings to light the newest and most relevant advances involving the state-of-the-art NIR fluorescent agents for the real-time interventional NIR fluorescence imaging of cancer in clinical trials.

The Accuracy of the Surgical Peritoneal Cancer Index in Patients with Peritoneal Metastases of Colorectal Cancer

INTRODUCTION

The peritoneal cancer index (PCI) is one of the most important prognostic factors in patients with peritoneal metastases from colorectal cancer undergoing cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS-HIPEC). The PCI is determined during laparotomy by 2 experienced surgeons and plays a major role in the decision to proceed with CRS-HIPEC. The primary objective of this study was to determine the accuracy of the surgical PCI (sPCI) by comparing it with the PCI confirmed by the pathologist (pPCI).

METHODS

All consecutive patients who underwent CRS-HIPEC for colorectal peritoneal metastases between February 2015 and June 2018 were identified. Relevant patient- and tumor-related characteristics were collected.

RESULTS

In total, 119 patients were included, 60 males (50.4%). The median age was 64 (IQR 55-71). The median sPCI (sPCI = 11, IQR 6-16) was significantly higher than the median pPCI (pPCI = 8, IQR 3-13, p < 0.001). The total pPCI was lower than the total sPCI in 80 patients (67.2%). In 21 patients (17.6%), the sPCI was overestimated with ≥5 points. Small lesions are more likely to be negative. In patients that underwent resection of their primary tumor prior to CRS-HIPEC, the difference between the sPCI and pPCI was significantly larger (p < 0.05).

CONCLUSIONS

Surgical calculation of the PCI often results in overestimation. Far-reaching consequences are tied to the macroscopic evaluation of the sPCI, but this evaluation seems not very reliable.

Intraoperative Fluorescence-Guided Surgery in Head and Neck Squamous Cell Carcinoma

The rate of positive margins in head and neck cancers has remained stagnant over the past three decades and is consistently associated with poor overall survival. This suggests that significant improvements must be made intraoperatively to ensure negative margins. We discuss the important role of fluorescence imaging to guide surgical oncology in head and neck cancer. This review includes a general overview of the principles of fluorescence, available fluorophores used for fluorescence imaging, and specific clinical applications of fluorescence-guided surgery, as well as challenges and future directions in head and neck surgical oncology. Laryngoscope, 131:529-534, 2021.

Research advances in integrated theranostic probes for tumor fluorescence visualization and treatment

At present, cancer is obviously a major threat to human health worldwide. Accurate diagnosis and treatment are in great demand and have become an effective method to alleviate the development of cancer and improve the survival rate of patients. A large number of theranostic probes that combine diagnosis and treatment methods have been developed as promising tools for tumor precision medicine. Among them, fluorescent theranostic probes have developed rapidly in the frontier research field of precision medicine with their real time, low toxicity, and high-resolution merit. Therefore, this review focuses on recent advances in the development of fluorescent theranostic probes, as well as their applications for cancer diagnosis and treatment. Initially, small-molecule fluorescent theranostic probes mainly including tumor microenvironment-responsive fluorescent prodrugs and phototherapeutic probes were introduced. Subsequently, nanocomposite probes are expounded based on four types of nano-fluorescent particles combining different therapies (chemotherapy, photothermal therapy, photodynamic therapy, gene therapy, etc.). Then, the capsule-type "all in one" probes, which occupy an important position in theranostic probes, are summarized according to the surface carrier type. This review aims to present a comprehensive guide for researchers in the field of tumor-related theranostic probe design and development.

Near-infrared fluorescence imaging in immunotherapy

Near-infrared (NIR) light possesses many suitable optophysical properties for medical imaging including low autofluorescence, deep tissue penetration, and minimal light scattering, which together allow for high-resolution imaging of biological tissue. NIR imaging has proven to be a noninvasive and effective real-time imaging methodology that provides a high signal-to-background ratio compared to other potential optical imaging modalities. In response to this, the use of NIR imaging has been extensively explored in the field of immunotherapy. To date, NIR fluorescence imaging has successfully offered reliable monitoring of the localization, dynamics, and function of immune responses, which are vital in assessing not only the efficacy but also the safety of treatments to design immunotherapies optimally. This review aims to provide an overview of the current research on NIR imaging of the immune response. We expect that the use of NIR imaging will expand further in response to the recent success in cancer immunotherapy. We will also offer our insights on how this technology will meet rapidly growing expectations in the future.

Indocyanine green fluorescence angiography-guided transoral endoscopic thyroidectomy and parathyroidectomy: First clinical report

BACKGROUND

Indocyanine green fluorescence (ICG) angiography has been used for many purposes including as part of a focused parathyroidectomy technique. Concomitant fluorescence of thyroid tissue may cause challenges defining parathyroid tissue during surgery, since ICG is not a selective fluorescent agent. On the other hand, cosmesis is still a big problem for patients due to the visible neck scars produced by the standard surgical technique. In this study, we described a novel technique to solve both these handicaps.

MATERIALS AND METHODS

Seven patients who underwent ICG fluorescence angiography-guided transoral endoscopic thyroidectomy and parathyroidectomy vestibular approach between February 2018 and July 2019 were included. Serum parathyroid hormone (PTH) levels were measured intraoperatively and on postoperative day 1. Fluorescent images were confirmed with intraoperative quick-PTH levels.

RESULTS

All operations were done successfully without conversion to open surgery. Intense and isolated parathyroid fluorescent images were achieved in all operations. All patients had a 50 % decrease between the baseline and final quick-PTH levels and the final quick-PTH levels were in the normal range in all. One of 7 patients had epistaxis due to nasotracheal intubation. One of 7 patients had seroma on post-operative day 5. None of patients had mental nerve injury, permanent hypocalcemia and temporary or permanent recurrent laryngeal nerve injury.

CONCLUSION

ICG-guided transoral endoscopic thyroid and parathyroid surgery can be used in select patients to increase operative success in focused parathyroidectomy with excellent cosmetic outcome also noted.

Design of fluorophore-loaded human serum albumin nanoparticles for specific targeting of NIH:OVCAR3 ovarian cancer cells

Nowadays, extensive research is being carried out to find innovative solutions for the development of stable, reproductible, and highly efficient fluorescent contrast agents with the ability of targeting specific cells, which can be further implemented for fluorescent-guided surgery in a real clinical setting. The present study is focused on the development of fluorescent dye-loaded protein nanoparticles (NPs) to overcome the drawbacks of the standard administration of free organic fluorophores, such as cytotoxicity, aqueousinstability, and rapid photo-degradation. Precisely, human serum albumin (HSA) NPs loaded with two different FDA approved dyes, namely indocyanine green (ICG) and fluorescein isothiocyanate (FITC), with a fluorescence response in the near-infrared and visible spectral domains, respectively, have been successfully designed. Even though the diameter of fluorescent HSA NPs is around 30 nm as proven by dynamic light scattering and transmission electron microscopy investigations, they present good loading efficiencies of almost 50% for ICG, and over 30% for FITC and a high particle yield of over 75%. Molecular docking simulations of ICG and FITC within the structure of HSA confirmed that the dyes were loaded inside the NPs, and docked in Site I (subdomain IIA) of the HSA molecule. After the confirmation of their high fluorescence photostability, the NPs were covalently conjugated with folic acid (HSA-FA NPs) in order to bind specifically to the folate receptor alpha (FRα) protein overexpressed on NIH:OVCAR3 ovarian cancer cells. Finally, fluorescence microscopy imaging investigations validate the improved internalization of folate targeted HSA&FITC NPs compared to cells treated with untargeted ones. Furthermore, TEM examinations of the distribution of HSA NPs into the NIH:OVCAR3 cells revealed anincreased number of NP-containing vesicles for the cells treated with HSA-FA NPs, compared to the cells exposed to untargeted HAS NPs, upholding the enhanced cellular uptake through FRα-mediated potocytosis.

Indocyanine green fluorescence-guided intraoperative detection of peritoneal carcinomatosis: systematic review

Background

To review the available clinical data about the value of Indocyanine Green (ICG) fluorescence imaging for intraoperative detection of peritoneal carcinomatosis.

Methods

We conducted a systematic review, according to the PRISMA guidelines, for clinical series investigating the possible role of ICG fluorescence imaging in detecting peritoneal carcinomatosis during surgical treatment of abdominal malignancies. With the aim to analyze actual application in the daily clinical practice, papers including trials with fluorophores other than ICG, in vitro and animals series were excluded. Data on patients and cancer features, timing, dose and modality of ICG administration, sensitivity, specificity and accuracy of fluorescence diagnosis of peritoneal nodules were extracted and analyzed.

Results

Out of 192 screened papers, we finally retrieved 7 series reporting ICG-guided detection of peritoneal carcinomatosis. Two papers reported the same cases, thus only 6 series were analyzed, for a total of 71 patients and 353 peritoneal nodules. The investigated tumors were colorectal carcinomas in 28 cases, hepatocellular carcinoma in 16 cases, ovarian cancer in 26 cases and endometrial cancer in 1 case. In all but 4 cases, the clinical setting was an elective intervention in patients known as having peritoneal carcinomatosis. No series reported a laparoscopic procedure. Technical data of ICG management were consistent across the studies. Overall, 353 lesions were harvested and singularly evaluated. Sensitivity varied from 72.4 to 100%, specificity from 54.2 to 100%. Two series reported that planned intervention changed in 25 and 29% of patients, respectively.

Conclusion

Indocyanine Green based fluorescence of peritoneal carcinomatosis is a promising intraoperative tool for detection and characterization of peritoneal nodules in patients with colorectal, hepatocellular, ovarian carcinomas. Further prospective studies are needed to fix its actual diagnostic value on these and other abdominal malignancies with frequent spread to peritoneum.

A preliminary study of dual-band confocal laser endomicroscopy combined with image mosaic in the diagnosis of liver cancer

Accurate identification of tumor tissues and their margins are still challenging for conventional clinical imaging methods during liver cancer surgery. In this study, dual-band confocal laser endomicroscopy (CLE) combined with image mosaic was used to guide liver cancer surgery. In the experiments with mice bearing orthotropic liver tumor, CLE can accurately detect the tumors and identify their margins with two excitation wavelengths of 488 nm and 660 nm by clinically available dyes fluorescein sodium (FS) or indocyanine green (ICG). The mosaic CLE images enlarged the imaging field and detected the liver tumor margins more accurately. Normal liver tissues fluorescence intensity of CLE images was significantly higher than that of tumor tissues in the same tumor-bearing mice (P < 0.0001). Overall, dual-band CLE imaging demonstrates to be a promising method to identify liver tumor tissues and margins, which has the prospect of clinical application and helps to achieve intraoperative radical resection.

Intraoperative near-infrared imaging can identify canine mammary tumors, a spontaneously occurring, large animal model of human breast cancer

Introduction

Current methods of intraoperative margin assessment in breast conserving surgery are impractical, unreliable, or time consuming. We hypothesized that intraoperative near-infrared (NIR) imaging with an FDA-approved NIR optical contrast agent could identify canine mammary tumors, a spontaneous large animal model of human breast cancer, during surgery.

Methods

Dogs with mammary tumors underwent a standard of care lumpectomy or mastectomy with wide surgical margins 20 hours after indocyanine green administration (3 mg/kg IV). During surgery, NIR imaging was performed on tumors and wound margins in situ and tumors and lymph nodes ex vivo. Following resection, the wound bed was examined for residual fluorescence. Fluorescence intensity was determined by signal-to-background ratio (SBR). All tumors, areas of residual fluorescence, and lymph nodes underwent histopathologic analysis.

Results

There were 41 mammary tumors in 16 female dogs. Twenty tumors were malignant and 21 were benign. Twenty-eight tumors were fluorescent (mean SBR 1.5±0.2). Sensitivity of fluorescence for all malignant tumors was 80% (16/20) and 93.3% (14/15) for malignant tumors > 2 cm. Specificity for malignancy was low (< 2cm = 55%; > 2cm = 30%). Tumors > 2 cm were more likely to be fluorescent (OR 6.05, 95% CI 1.50–24.44, P = 0.011) but not more likely to be malignant (OR 3.09, 95% CI 0.86–11.14, P = 0.085) than tumors ≤ 2 cm. Four out of seven inguinal lymph nodes excised in the mastectomy specimen fluoresced. All four drained malignant tumors; however only 2/4 contained metastatic disease.

Conclusion

Systemic ICG accumulates reliably in malignant canine mammary tumors > 2 cm. Although no tumor margins fluoresced, a wider margin of normal tissue is removed in canine mastectomy, making direct comparisons with breast conserving surgery difficult. Targeted NIR imaging agents are likely required to improve detection of smaller tumors and improve the specificity of NIR imaging for residual disease and metastatic lymph node detection.