In recent years, the use of fluorescence-guided surgery (FGS) to treat benign and malignant visceral, hepatobiliary and pancreatic neoplasms has significantly increased. FGS relies on the ...fluorescence signal emitted by injected substances (fluorophores) after being illuminated by ad hoc laser sources to help guide the surgical procedure and provide the surgeon with real-time visualization of the fluorescent structures of interest that would be otherwise invisible. This review surveys and discusses the most common and emerging clinical applications of indocyanine green (ICG)-based fluorescence in visceral, hepatobiliary and pancreatic surgery. The analysis, findings, and discussion presented here rely on the authors' significant experience with this technique in their medical institutions, an up-to-date review of the most relevant articles published on this topic between 2014 and 2018, and lengthy discussions with key opinion leaders in the field during recent conferences and congresses. For each application, the benefits and limitations of this technique, as well as applicable future directions, are described. The imaging of fluorescence emitted by ICG is a simple, fast, relatively inexpensive, and harmless tool with numerous different applications in surgery for both neoplasms and benign pathologies of the visceral and hepatobiliary systems. The ever-increasing availability of visual systems that can utilize this tool will transform some of these applications into the standard of care in the near future. Further studies are needed to evaluate the strengths and weaknesses of each application of ICG-based fluorescence imaging in abdominal surgery.
Near‐infrared (NIR) fluorescence imaging is gaining clinical acceptance over the last years and has been used for detection of lymph nodes, several tumor types, vital structures and tissue perfusion. ...This review focuses on NIR fluorescence imaging with indocyanine green and methylene blue for different clinical applications in abdominal surgery with an emphasis on oncology, based on a systematic literature search. Furthermore, practical information on doses, injection times, and intraoperative use are provided.
Background
Augmented reality (AR) in surgery consists in the fusion of synthetic computer-generated images (3D virtual model) obtained from medical imaging preoperative workup and real-time patient ...images in order to visualize unapparent anatomical details. The 3D model could be used for a preoperative planning of the procedure. The potential of AR navigation as a tool to improve safety of the surgical dissection is outlined for robotic hepatectomy.
Materials and methods
Three patients underwent a fully robotic and AR-assisted hepatic segmentectomy. The 3D virtual anatomical model was obtained using a thoracoabdominal CT scan with a customary software (VR-RENDER®, IRCAD). The model was then processed using a VR-RENDER® plug-in application, the Virtual Surgical Planning (VSP®, IRCAD), to delineate surgical resection planes including the elective ligature of vascular structures. Deformations associated with pneumoperitoneum were also simulated. The virtual model was superimposed to the operative field. A computer scientist manually registered virtual and real images using a video mixer (MX 70; Panasonic, Secaucus, NJ) in real time.
Results
Two totally robotic AR segmentectomy V and one segmentectomy VI were performed. AR allowed for the precise and safe recognition of all major vascular structures during the procedure. Total time required to obtain AR was 8 min (range 6–10 min). Each registration (alignment of the vascular anatomy) required a few seconds. Hepatic pedicle clamping was never performed. At the end of the procedure, the remnant liver was correctly vascularized. Resection margins were negative in all cases. The postoperative period was uneventful without perioperative transfusion.
Conclusions
AR is a valuable navigation tool which may enhance the ability to achieve safe surgical resection during robotic hepatectomy.
Background
Hyperspectral imaging (HSI) is a relatively new method used in image-guided and precision surgery, which has shown promising results for characterization of tissues and assessment of ...physiologic tissue parameters. Previous methods used for analysis of preconditioning concepts in patients and animal models have shown several limitations of application. The aim of this study was to evaluate HSI for the measurement of ischemic conditioning effects during esophagectomy.
Methods
Intraoperative hyperspectral images of the gastric tube through the mini-thoracotomy were recorded from
n
= 22 patients, 14 of whom underwent laparoscopic gastrolysis and ischemic conditioning of the stomach with two-step transthoracic esophagectomy and gastric pull-up with intrathoracic anastomosis after 3–7 days. The tip of the gastric tube (later esophagogastric anastomosis) was measured with HSI. Analysis software provides a RGB image and 4 false color images representing physiologic parameters of the recorded tissue area intraoperatively. These parameters contain tissue oxygenation (StO
2
), perfusion—(NIR Perfusion Index), organ hemoglobin (OHI), and tissue water index (TWI).
Results
Intraoperative HSI of the gastric conduit was possible in all patients and did not prolong the regular operative procedure due to its quick applicability. In particular, the tissue oxygenation of the gastric conduit was significantly higher in patients who underwent ischemic conditioning (
St
O
2
¯
Precond
.
= 78%;
St
O
2
¯
NoPrecond
.
= 66%;
p
= 0.03).
Conclusions
HSI is suitable for contact-free, non-invasive, and intraoperative evaluation of physiological tissue parameters within gastric conduits. Therefore, HSI is a valuable method for evaluating ischemic conditioning effects and may contribute to reduce anastomotic complications. Additional studies are needed to establish normal values and thresholds of the presented parameters for the gastric conduit anastomotic site.
Currently, colorectal cancer (CRC) is mainly identified via a visual assessment during colonoscopy, increasingly used artificial intelligence algorithms, or surgery. Subsequently, CRC is confirmed ...through a histopathological examination by a pathologist. Hyperspectral imaging (HSI), a non-invasive optical imaging technology, has shown promising results in the medical field. In the current study, we combined HSI with several artificial intelligence algorithms to discriminate CRC. Between July 2019 and May 2020, 54 consecutive patients undergoing colorectal resections for CRC were included. The tumor was imaged from the mucosal side with a hyperspectral camera. The image annotations were classified into three groups (cancer, CA; adenomatous margin around the central tumor, AD; and healthy mucosa, HM). Classification and visualization were performed based on a four-layer perceptron neural network. Based on a neural network, the classification of CA or AD resulted in a sensitivity of 86% and a specificity of 95%, by means of leave-one-patient-out cross-validation. Additionally, significant differences in terms of perfusion parameters (e.g., oxygen saturation) related to tumor staging and neoadjuvant therapy were observed. Hyperspectral imaging combined with automatic classification can be used to differentiate between CRC and healthy mucosa. Additionally, the biological changes induced by chemotherapy to the tissue are detectable with HSI.
Virtual reality (VR) and augmented reality (AR) in complex surgery are evolving technologies enabling improved preoperative planning and intraoperative navigation. The basis of these technologies is ...a computer-based generation of a patient-specific 3-dimensional model from Digital Imaging and Communications in Medicine (DICOM) data. This article provides a state-of-the- art overview on the clinical use of this technology with a specific focus on hepatic surgery. Although VR and AR are still in an evolving stage with only some clinical application today, these technologies have the potential to become a key factor in improving preoperative and intraoperative decision making.
Significance: Hyperspectral imaging (HSI) can support intraoperative perfusion assessment, the identification of tissue structures, and the detection of cancerous lesions. The practical use of HSI ...for minimal-invasive surgery is currently limited, for example, due to long acquisition times, missing video, or large set-ups.
Aim: An HSI laparoscope is described and evaluated to address the requirements for clinical use and high-resolution spectral imaging.
Approach: Reflectance measurements with reference objects and resected human tissue from 500 to 1000 nm are performed to show the consistency with an approved medical HSI device for open surgery. Varying object distances are investigated, and the signal-to-noise ratio (SNR) is determined for different light sources.
Results: The handheld design enables real-time processing and visualization of HSI data during acquisition within 4.6 s. A color video is provided simultaneously and can be augmented with spectral information from push-broom imaging. The reflectance data from the HSI system for open surgery at 50 cm and the HSI laparoscope are consistent for object distances up to 10 cm. A standard rigid laparoscope in combination with a customized LED light source resulted in a mean SNR of 30 to 43 dB (500 to 950 nm).
Conclusions: Compact and rapid HSI with a high spatial- and spectral-resolution is feasible in clinical practice. Our work may support future studies on minimally invasive HSI to reduce intra- and postoperative complications.
Background
Clinical evaluation of the demarcation line separating ischemic from non-ischemic liver parenchyma may be challenging. Hyperspectral imaging (HSI) is a noninvasive imaging modality, which ...combines a camera with a spectroscope and allows quantitative imaging of tissue oxygenation. Our group developed a software to overlay HSI images onto the operative field, obtaining HSI-based enhanced reality (HYPER). The aim of the present study was to evaluate the accuracy of HYPER to identify the demarcation line after a left vascular inflow occlusion during an anatomical left hepatectomy.
Materials and methods
In the porcine model (
n
= 3), the left branches of the hepatic pedicle were ligated. Before and after vascular occlusion, HSI images based on tissue oxygenation (StO
2
), obtained through the Near-Infrared index (NIR index), were regularly acquired and superimposed onto RGB video. The demarcation line was marked on the liver surface with electrocautery according to HYPER. Local lactates were measured on blood samples from the liver surface in both ischemic and perfused segments using a strip-based device. At the same areas, confocal endomicroscopy was performed.
Results
After ligation, HSI demonstrated a significantly lower oxygenation (NIR index) in the left medial lobe (LML) (0.27% ± 0.21) when compared to the right medial lobe (RML) (58.60% ± 12.08;
p
= 0.0015). Capillary lactates were significantly higher (3.07 mmol/L ± 0.84 vs. 1.33 ± 0.71 mmol/L;
p
= 0.0356) in the LML versus RML, respectively. Concordantly, confocal videos demonstrated the absence of blood flow in the LML and normal perfusion in the RML.
Conclusions
HYPER has made it possible to correctly identify the demarcation line and quantify surface liver oxygenation. HYPER could be an intraoperative tool to guide perfusion-based demarcation line assessment and segmentation.
Background
Augmented reality (AR) is the fusion of computer-generated and real-time images. AR can be used in surgery as a navigation tool, by creating a patient-specific virtual model through 3D ...software manipulation of DICOM imaging (e.g., CT scan). The virtual model can be superimposed to real-time images enabling transparency visualization of internal anatomy and accurate localization of tumors. However, the 3D model is rigid and does not take into account inner structures’ deformations. We present a concept of automated AR registration, while the organs undergo deformation during surgical manipulation, based on finite element modeling (FEM) coupled with optical imaging of fluorescent surface fiducials.
Methods
Two 10 × 1 mm wires (pseudo-tumors) and six 10 × 0.9 mm fluorescent fiducials were placed in ex vivo porcine kidneys (
n
= 10). Biomechanical FEM-based models were generated from CT scan. Kidneys were deformed and the shape changes were identified by tracking the fiducials, using a near-infrared optical system. The changes were registered automatically with the virtual model, which was deformed accordingly. Accuracy of prediction of pseudo-tumors’ location was evaluated with a CT scan in the deformed status (ground truth). In vivo: fluorescent fiducials were inserted under ultrasound guidance in the kidney of one pig, followed by a CT scan. The FEM-based virtual model was superimposed on laparoscopic images by automatic registration of the fiducials.
Results
Biomechanical models were successfully generated and accurately superimposed on optical images. The mean measured distance between the estimated tumor by biomechanical propagation and the scanned tumor (ground truth) was 0.84 ± 0.42 mm. All fiducials were successfully placed in in vivo kidney and well visualized in near-infrared mode enabling accurate automatic registration of the virtual model on the laparoscopic images.
Conclusions
Our preliminary experiments showed the potential of a biomechanical model with fluorescent fiducials to propagate the deformation of solid organs’ surface to their inner structures including tumors with good accuracy and automatized robust tracking.
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