Near-Infrared Fluorescence Imaging for Real-Time Intraoperative Anatomical Guidance in Minimally Invasive Surgery: A Systematic Review of the Literature

Indocyanine green in gynecologic surgery: Where do we stand? A literature review and meta-analysis

The main objective of this study was to review and perform a meta-analysis of current literature on the use of indocyanine green for sentinel lymph node detection in pelvic gynecologic cancer. We included all studies focusing on indications and procedures associated with the use of ICG in gynecologic surgery and available on the Medline and Pubmed database. For the meta-analysis, random effect models were used for estimation of the 95 % detection rate and 95 % confidence interval, and stratified analyses by cancer type, concentration and localization of injection were performed. A total of 147 articles were included, of which 91 were studied in a meta-analysis. Results concerning detection rate by indocyanine green injection site were found to be 95.1 % and 97.3 % respectively for intracervical injection in 2 or 4 quadrants, and 77.0 % and 94.8 % for hysteroscopic and intradermal injection respectively. Results concerning detection rate by cancer type were 95.8 %, 95.2 %, 94.7 % and 95.7 % respectively for cervical, endometrial, vulvar and endometrial/cervical cancers. Finally, the results concerning detection rate by indocyanine green concentration were 91.2 %, 95.7 %, 96.7 % and 97.7 % for concentrations of <1.25 mg/ml, 1.25 mg/ml, 2.5 mg/ml and 5 mg/ml respectively. In conclusion, indocyanine green is shown to allow highlighting of sentinel lymph nodes with good reliability with an overall indocyanine green detection rate of 95.5 %. Our literature review revealed that indocyanine green feasibility has also been demonstrated in several surgical contexts, notably for reconstructive surgery and detection of endometriosis.

"The Green Peace" How ICG can prevent complications in endometriosis surgery?

This literature review summarises the investigation into using Indocyanine Green (ICG) in the surgical management of endometriosis, focusing mainly on its application in Deep Endometriosis (DE). The study reviews the development, fluorescence characteristics, and clinical usage of ICG in enhancing the precision of identifying endometrial lesions during surgery. Emphasizing the technology's contribution to improved lesion visualisation, the paper discusses how ICG facilitates increased diagnostic accuracy, potentially reducing recurrence rates and the necessity for subsequent interventions. Additionally, it explores ICG's role in minimizing the risk of iatrogenic injuries, especially in ureteral endometriosis, and its utility in surgical decision-making for rectosigmoid endometriosis by evaluating bowel perfusion. Conclusively, while acknowledging the clear benefits of ICG integration in endometriosis surgical procedures, the abstract calls for more extensive research to validate its efficacy and cost-efficiency in the broader context of endometriosis treatment.

Minimally Invasive Surgery for Hirschsprung Disease: Current Practices and Future Directions

Hirschsprung disease (HD) is a congenital disorder characterized by the absence of ganglion cells in the distal colon and rectum, leading to functional obstruction and severe constipation. Over the past decades, the surgical management of HD has significantly evolved, with minimally invasive surgery (MIS) techniques revolutionizing treatment approaches. This review explores recent innovations in MIS for HD, focusing on laparoscopic, transanal endorectal pull-through (TERPT), and robotic-assisted techniques. These approaches offer numerous advantages over traditional open procedures, including reduced surgical trauma, improved cosmesis, faster recovery times, and potentially lower complication rates. Laparoscopic surgery has become widely adopted, providing excellent visualization and precise dissection. TERPT has gained popularity for short-segment disease, offering a completely transanal approach with minimal scarring. Robotic-assisted surgery represents the cutting edge, enhancing surgical precision and dexterity. The review also examines emerging technologies and future directions, such as advanced imaging techniques, artificial intelligence applications, and potential developments in tissue engineering. While MIS techniques have shown promising outcomes, challenges remain in standardizing approaches, addressing long-segment disease, and optimizing long-term functional results. The future of HD surgery lies in personalized approaches that integrate genetic and molecular profiling with advanced surgical technologies. As the field continues to evolve, comprehensive long-term studies and efforts to improve access to specialized care will be crucial to further enhancing outcomes for patients with HD.

Intraoperative image-guidance during robotic surgery: is there clinical evidence of enhanced patient outcomes?

BACKGROUND

To date, the benefit of image guidance during robot-assisted surgery (IGS) is an object of debate. The current study aims to address the quality of the contemporary body of literature concerning IGS in robotic surgery throughout different surgical specialties.

METHODS

A systematic review of all English-language articles on IGS, from January 2013 to March 2023, was conducted using PubMed, Cochrane library's Central, EMBASE, MEDLINE, and Scopus databases. Comparative studies that tested performance of IGS vs control were included for the quantitative synthesis, which addressed outcomes analyzed in at least three studies: operative time, length of stay, blood loss, surgical margins, complications, number of nodal retrievals, metastatic nodes, ischemia time, and renal function loss. Bias-corrected ratio of means (ROM) and bias-corrected odds ratio (OR) compared continuous and dichotomous variables, respectively. Subgroup analyses according to guidance type (i.e., 3D virtual reality vs ultrasound vs near-infrared fluoresce) were performed.

RESULTS

Twenty-nine studies, based on 11 surgical procedures of three specialties (general surgery, gynecology, urology), were included in the quantitative synthesis. IGS was associated with 12% reduction in length of stay (ROM 0.88; p = 0.03) and 13% reduction in blood loss (ROM 0.87; p = 0.03) but did not affect operative time (ROM 1.00; p = 0.9), or complications (OR 0.93; p = 0.4). IGS was associated with an estimated 44% increase in mean number of removed nodes (ROM 1.44; p < 0.001), and a significantly higher rate of metastatic nodal disease (OR 1.82; p < 0.001), as well as a significantly lower rate of positive surgical margins (OR 0.62; p < 0.001). In nephron sparing surgery, IGS significantly decreased renal function loss (ROM 0.37; p = 0.002).

CONCLUSIONS

Robot-assisted surgery benefits from image guidance, especially in terms of pathologic outcomes, namely higher detection of metastatic nodes and lower surgical margins. Moreover, IGS enhances renal function preservation and lowers surgical blood loss.

Current applications of indocyanine green (ICG) in abdominal, gynecologic and urologic surgery: a meta-review and quality analysis with use of the AMSTAR 2 instrument

BACKGROUND

Indocyanine green (ICG) is an injectable fluorochrome that has recently gained popularity as a means of assisting intraoperative visualization during laparoscopic and robotic surgery. Many systematic reviews and meta-analyses have been published. We conducted a meta-review to synthesize the findings of these studies.

METHODS

PubMed and Embase were searched to identify systematic reviews and meta-analyses coping with the uses of ICG in abdominal operations, including Metabolic Bariatric Surgery, Cholecystectomy, Colorectal, Esophageal, Gastric, Hepato-Pancreato-Biliary, Obstetrics and Gynecology (OG), Pediatric Surgery, Surgical Oncology, Urology, (abdominal) Vascular Surgery, Adrenal and Splenic Surgery, and Interdisciplinary tasks, until September 2023. We submitted the retrieved meta-analyses to qualitative analysis based on the AMSTAR 2 instrument.

RESULTS

We identified 116 studies, 41 systematic reviews (SRs) and 75 meta-analyses (MAs), spanning 2013-2023. The most thoroughly investigated (sub)specialties were Colorectal (6 SRs, 25 MAs), OG (9 SRs, 15 MAs), and HPB (4 SRs, 12 MAs). Interestingly, there was high heterogeneity regarding the administered ICG doses, routes, and timing. The use of ICG offered a clear benefit regarding anastomotic leak prevention, particularly after colorectal and esophageal surgery. There was no clear benefit regarding sentinel node detection after OG. According to the AMSTAR 2 tool, most meta-analyses ranked as "critically low" (34.7%) or "low" (58.7%) quality. There were only five meta-analyses (6.7%) that qualified as "moderate" quality, whereas there were no "high" quality reviews.

CONCLUSIONS

Regardless of the abundance of pertinent literature and reviews, surgeons should be cautious when interpreting their results on ICG use in abdominal surgery. Future reviews should focus on ensuring methodological vigor; establishing clear protocols of ICG dose, route of administration, and timing; and improving reporting quality. Other sources of data (e.g., registries) and novel methods of data analysis (e.g., machine learning) might also contribute to an enhanced role of ICG as a decision-making tool in surgery.

Microsurgery Robots: Applications, Design, and Development

Microsurgical techniques have been widely utilized in various surgical specialties, such as ophthalmology, neurosurgery, and otolaryngology, which require intricate and precise surgical tool manipulation on a small scale. In microsurgery, operations on delicate vessels or tissues require high standards in surgeons' skills. This exceptionally high requirement in skills leads to a steep learning curve and lengthy training before the surgeons can perform microsurgical procedures with quality outcomes. The microsurgery robot (MSR), which can improve surgeons' operation skills through various functions, has received extensive research attention in the past three decades. There have been many review papers summarizing the research on MSR for specific surgical specialties. However, an in-depth review of the relevant technologies used in MSR systems is limited in the literature. This review details the technical challenges in microsurgery, and systematically summarizes the key technologies in MSR with a developmental perspective from the basic structural mechanism design, to the perception and human-machine interaction methods, and further to the ability in achieving a certain level of autonomy. By presenting and comparing the methods and technologies in this cutting-edge research, this paper aims to provide readers with a comprehensive understanding of the current state of MSR research and identify potential directions for future development in MSR.

Internal reflectance cell fluorescence measurement combined with multi-way analysis to detect fluorescence signatures of undiluted honeys and a fusion of fluorescence and NIR to enhance predictability

Honey is a complex food matrix that contains diverse polyphenolic compounds. Some phenolics exhibit fluorescence signatures which can be used to evaluate honey quality, and authenticity and to determine botanical origin. Mānuka honey contains two unique fluorescence markers: Leptosperin (MM1) and Lepteridine^TM (MM2) that are derived from Leptospermum scoparium nectar. Fluorescence measurement of supersaturated solutions such as undiluted honeys can be challenged by complex inner filter effects. The current study shows the ability of internal reflectance cell fluorescence measurement and multi-way analysis to detect fluorophores in undiluted honeys. This study scanned honeys from different geographic districts generating excitation emission matrices (250-400/300-600 nm), and by near infrared (NIR) hyperspectral camera (547-1701 nm). PARAFAC and tri-PLS could track two fluorescence markers: MM1 (R² = 0.82 & RMSEP = 138.65) and MM2 (R² = 0.82 & RMSEP = 2.75) from undiluted honey fluorescence data with > 80 % accuracy. Classification of mono-floral, multi-floral and non-mānuka honeys achieved 90 % overall accuracy. Fusion of fluorescence data at ƛ_ex 270 & 330 nm and NIR hyperspectral data combined with multi-block PLS analysis enhances predictability of fluorescence markers further. The study revealed the potential of internal reflectance cell fluorescence measurement combined with chemometrics and data fusion for rapid evaluation of honey quality and botanical origin.

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.

Fluorescent Indocyanine Green versus Technetium-99m and Blue Dye for Bilateral SENTinel Lymph Node Detection in Stage I-IIA Cervical Cancer (FluoreSENT): protocol for a non-inferiority study

INTRODUCTION

Nowadays, two predominant methods for detecting sentinel lymph nodes (SLNs) in cervical cancer are in use. The most conventional method is a combination of a radiotracer, technetium-99m (^99mTc) and blue dye. More recently, another method for SLN mapping using indocyanine green (ICG) is becoming widely accepted. ICG is a fluorescent dye, visualised intraoperatively with near-infrared (NIR) fluorescence imaging, providing real-time visual navigation. The presumed advantages of ICG over ^99mTc, that is, being cheaper, non-radioactive and logistically more attractive, are only valuable if its detection rate proves to be at least non-inferior. Before omitting the well-functioning and evidence-based combined approach of ^99mTc and blue dye, we aim to provide prospective evidence on the non-inferiority of ICG with NIR fluorescence imaging.

METHODS AND ANALYSIS

We initiated a prospective non-inferiority study with a paired comparison of both SLN methods in a single sample of 101 patients with International Federation of Gynecology and Obstetrics (FIGO) stage IA-IB2 or IIA1 cervical cancer receiving primary surgical treatment. All patients undergo SLN mapping with ICG and NIR fluorescence imaging in adjunct to mapping with ^99mTc (including single photon emission computed tomography with X-ray computed tomography (SPECT/CT)) and blue dye. Surgeons start SLN detection with ICG while being blinded for the preoperative outcome of SPECT/CT to avoid biased detection with ICG. Primary endpoint of this study is bilateral SLN detection rate of both methods (ie, detection of at least one SLN in each hemipelvis). Since we compare strategies for SLN mapping that are already applied in current daily practice for different types of cancer, no additional risks or burdens are expected from these study procedures.

ETHICS AND DISSEMINATION

The current study is approved by the Medical Ethics Research Committee Utrecht (reference number 21-014). Findings arising from this study will be disseminated in peer-reviewed journals, academic conferences and through patient organisations.

TRIAL REGISTRATION NUMBER

NL9011 and EudraCT 2020-005134-15.

Recent advances of aggregation-induced emission materials for fluorescence image-guided surgery

Real-time intraoperative guidance is essential during various surgical treatment of many diseases. Aggregation-induced emission (AIE) materials have shown great potential for guiding surgeons during complex interventions, with the merits of deep tissue penetration, high quantum yield, high molar absorptivity, low background, good targeting ability and excellent photostability. Herein, we provided insights to design efficient AIE materials regarding three key parameters, i.e., deep-tissue penetration ability, high brightness of AIE luminogens (AIEgens), and precise tumor/other pathology nidus targeting strategies, for realizing better application of fluorescence image-guided surgery. Representative interdisciplinary achievements were outlined for the demonstration of this emerging field. Challenges and future opportunities of AIE materials were briefly discussed. The aim of this review is to provide a comprehensive view of AIE materials for intraoperative guidance for researchers and surgeons, and to inspire more further correlational studies in the new frontiers of image-guided surgery.

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.

Real-Time Intraoperative Ureteral Identification in Minimally Invasive Colorectal Surgery: A Systematic Review

Background: Although colorectal surgery (CRS) has currently almost entirely standardized surgical procedures, it can still show pitfalls such as the intraoperative ureteral injury. Intraoperative ureteral identification (IUI) could reduce the ureteral injuries rate but evidence is still lacking. We aimed to analyze the utility and the effectiveness of real-time IUI in minimally invasive CRS. Materials and Methods: A systematic review was performed examining available data on randomized and nonrandomized studies evaluating the utility of intraureteral fluorescence dye (IFD) and lighted ureteral stent (LUS) for intraoperative identification of ureters in CRS, in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) standards. Primary endpoint was ureteral injuries rate. Secondary endpoints included acute kidney injury, hematuria, urinary tract infections (UTI), and fluorescence assessment. Results: After literature search, 158 studies have been recorded, 36 studies underwent full-text reviews and 12 studies met inclusion criteria. Overall, out of a total of 822 patients who successfully received IUI, 3 (0.33%) patients experienced ureteral injury. Hematuria was reported in 689 (97.6%) of patients following LUS-guided surgery and in 1 (2%) patient following IFD-guided surgery, although transient in all cases. UTI was reported in 15 (3.3%) LUS-guided resections and in 1 (2%) IFD-guided resections. Acute kidney injury occurred in 23 (2.5%) LUS-guided surgery and 1 (1%) IFD-guided surgery. Conclusions: Real-time ureteral identification techniques could represent a valid solution in complex minimally invasive CRS, safely, with no time consuming and always reproducible by surgeons. Prospective studies will be needed to confirm these findings.

Collagen-Targeted Peptides for Molecular Imaging of Diffuse Cardiac Fibrosis

Background Cardiac fibrosis is the excessive deposition of extracellular matrix in the heart, triggered by a cardiac insult, aging, genetics, or environmental factors. Molecular imaging of the cardiac extracellular matrix with targeted probes could improve diagnosis and treatment of heart disease. However, although this technology has been used to demonstrate focal scarring arising from myocardial infarction, its capacity to demonstrate extracellular matrix expansion and diffuse cardiac fibrosis has not been assessed. Methods and Results Here, we report the use of collagen-targeted peptides labeled with near-infrared fluorophores for the detection of diffuse cardiac fibrosis in the β2-AR (β-2-adrenergic receptor) overexpressing mouse model and in ischemic human hearts. Two approaches were evaluated, the first based on a T peptide that binds matrix metalloproteinase-2-proteolyzed collagen IV, and the second on the cyclic peptide EP-3533, which targets collagen I. The systemic and cardiac uptakes of both peptides (intravenously administered) were quantified ex vivo by near-infrared imaging of whole organs, tissue sections, and heart lysates. The peptide accumulation profiles corresponded to an immunohistochemically-validated increase in collagen types I and IV in hearts of transgenic mice versus littermate controls. The T peptide could encouragingly demonstrate both the intermediate (7 months old) and severe (11 months old) cardiomyopathic phenotypes. Co-immunostainings of fluorescent peptides and collagens, as well as reduced collagen binding of a control peptide, confirmed the collagen specificity of the tracers. Qualitative analysis of heart samples from patients with ischemic cardiomyopathy compared with nondiseased donors supported the collagen-enhancement capabilities of these peptides also in the clinical settings. Conclusions Together, these observations demonstrate the feasibility and translation potential of molecular imaging with collagen-binding peptides for noninvasive imaging of diffuse cardiac fibrosis.

Laparoscopic liver cyst fenestration with real-time indocyanine green fluorescence-guided surgery: a case report

Laparoscopic fenestration (LF) has recently been considered a standard procedure for nonparasitic symptomatic liver cysts. Here, we report a case of LF that was safely performed using real-time indocyanine green (ICG) fluorescence-guided surgery. A 74-year-old woman presented with right upper abdominal pain and poor dietary intake. The patient was diagnosed with symptomatic liver cysts and underwent LF. One hour before surgery, ICG (2.5 mg) was intravenously administered to the patient. ICG fluorescence imaging clearly showed the biliary ducts and distinguished the cysts from the liver parenchyma. We could resect only the cyst walls as wide as possible under the guidance of both white light and fluorescence imaging. There were no signs of postoperative symptom recurrence. Detection of ICG fluorescence in the liver parenchyma is as important as ICG cholangiography for fenestration. Laparoscopic liver cyst fenestration with real-time ICG fluorescence-guided surgery is safe and can be used as a standard procedure.

Indocyanine green versus technetium-99m with blue dye for sentinel lymph node detection in early-stage cervical cancer: A systematic review and meta-analysis

Background

The fluorescent dye indocyanine green (ICG) has emerged as a promising tracer for intraoperative detection of sentinel lymph nodes (SLNs) in early‐stage cervical cancer. Although researchers suggest the SLN detection of ICG is equal to the more conventional combined approach of a radiotracer and blue dye, no consensus has been reached.

Aims

We aimed to assess the differences in overall and bilateral SLN detection rates with ICG versus the combined approach, the radiotracer technetium‐99m (^99mTc) with blue dye.

Methods and Results

We searched MEDLINE, Embase, and the Cochrane Library from inception to January 1, 2020 and included studies reporting on a comparison of SLN detection with ICG versus ^99mTc with blue dye in early‐stage cervical cancer. The overall and bilateral detection rates were pooled with random‐effects meta‐analyses.

From 118 studies retrieved seven studies (one cross‐sectional; six retrospective cohorts) were included, encompassing 589 patients. No significant differences were found in the pooled overall SLN detection rate of ICG versus ^99mTc with blue dye. Meta‐analyses of all studies showed ICG to result in a higher bilateral SLN detection rate than ^99mTc with blue dye; 90.3% (95%CI, 79.8‐100.0%) with ICG versus 73.5% (95%CI, 66.4‐80.6%) with 99mTc with blue dye. This resulted in a significant and clinically relevant risk difference of 16.6% (95%CI, 5.3‐28.0%). With sensitivity analysis, the risk difference of the bilateral detection rate maintained in favor of ICG but was no longer significant (13.2%, 95%CI −0.8‐27.3%).

Conclusion

ICG appears to provide higher bilateral SLN detection rates compared to ^99mTc with blue dye in patients with early‐stage cervical cancer. However, in adherence with the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) guidelines, the quality of evidence is too low to provide strong recommendations and directly omit the combined approach of ^99mTc with blue dye.

Sentinel Lymph Node Biopsy Is Feasible in Cervical Cancer Laparoscopic Surgery: A Single-Center Retrospective Cohort Study

Methods

A total of 100 cervical cancer patients undergoing laparoscopic surgery with SLN biopsy were included. Indocyanine green, carbon nanoparticles (CNPs), and a combination of both were used during surgeries. Detection rates, sensitivity, negative predictive value (NPV) of SLN biopsy, and related factors were analyzed.

Results

The overall and bilateral SLN detection rates were 92% (92/100) and 74% (74/100), respectively. Combined tracers had higher bilateral SLN detection rates than CNPs alone (p=0.005). Menopause and lymph node metastasis were associated with lower overall and bilateral SLN detection rates (p < 0.05). SLN biopsy sensitivity and NPV for lymph node metastasis in patients with at least one detected SLN were 81.8% (9/11) and 97.3% (72/74), respectively. Among those with bilateral detected SLNs, higher sensitivity and NPV of 87.5% (7/8) and 98.3% (57/58) were observed, respectively. SLN algorithm can ensure that all patients with lymph node metastasis are detected by SLN biopsy.

Conclusion

SLN biopsy appears to be safe and effective for specific cervical cancer patients with high detection rates and NPV in laparoscopic surgery, especially for those with detected bilateral SLNs and undergoing the SLN algorithm. Selecting suitable patients for SLN mapping has prospects for clinical application.

The role of near-infrared fluorescence imaging with indocyanine green dye in pedicle division with the paramedian forehead flap

The paramedian forehead flap is considered the gold standard for nasal reconstruction following oncologic surgery. During the 21-day delay in two-stage surgery protocols, many patients report considerably reduced quality of life because of the pedicle. This prospective case series study examined the usefulness of near-infrared (NIR) fluorescence with indocyanine green (ICG) for flap perfusion assessment and identified variables associated with time to flap perfusion. Ten patients (mean age 75.3 ± 11.6 years) with diagnosis of basal cell carcinoma (n = 9) or squamous cell carcinoma (n = 1) underwent intravenous indocyanine injection and NIR fluorescence imaging for assessment of flap vascularisation 2 to 3 weeks after stage 1 surgery. NIR fluorescence imaging showed 90% to 100% perfusion areas in all patients after 14 to 21 days. Early pedicle division occurred in two patients on postoperative days 14 and 16. One minor complication (wound healing disorder) was seen following flap takedown after 14 days. There were no associations between time to flap perfusion and defect size or flap area. NIR fluorescence imaging with ICG dye is a useful method for non-invasive perfusion assessment when used in conjunction with clinical assessment criteria. However, a decision for early pedicle division may raise risk of complications in specific patient groups and must therefore be made with great care.

Organic Dots with Large π-Conjugated Planar for Cholangiography beyond 1500 nm in Rabbits: A Non-Radioactive Strategy

Iatrogenic extrahepatic bile duct injury remains a dreaded complication while performing cholecystectomy. Although X-ray based cholangiography could reduce the incidence of biliary tract injuries, the deficiencies including radiation damage and expertise dependence hamper its further clinical application. The effective strategy for intraoperative cholangiography is still urgently required. Herein, a fluorescence-based imaging approach for cholangiography in the near-infrared IIb window (1500-1700 nm) using TT3-oCB, a bright aggregation-induced emission luminogen with large π-conjugated planar unit, is reported. In phantom studies, TT3-oCB nanoparticles exhibit high near-infrared IIb emission and show better image clarity at varying penetrating depths. When intrabiliary injected into the gallbladder or the common bile duct of the rabbit, TT3-oCB nanoparticles enable the real-time imaging of the biliary structure with deep penetrating capability and high signal-to-background ratio. Moreover, the tiny iatrogenic biliary injuries and the gallstones in established disease models could be precisely diagnosed by TT3-oCB nanoparticle assisted near-infrared IIb imaging. In summary, we reported a feasible application for aggregation-induced emission dots as biliary contrast agent and realized high-quality cholangiography in the near-infrared IIb window with precise diagnostic ability and nonradioactive damage, which could possibly be applied for intraoperative diagnosis.

Fluorescent cholangiography significantly improves patient outcomes for laparoscopic cholecystectomy

BACKGROUND

Laparoscopic cholecystectomy (LC) is the most common elective abdominal surgery in the USA, with over 750,000 performed annually. Fluorescent cholangiography (FC) using indocyanine green dye (ICG) permits identification of extrahepatic biliary structures to facilitate dissection without requiring cystic duct cannulation. Achieving the "critical view of safety" with assistance of ICG cholangiogram may support identification of anatomy, safely reduce conversion to open procedures, and decrease operative time. We assess the utility of FC with respect to anatomic visualization during LC and its effects on patient outcomes.

METHODS

A retrospective review of a prospectively maintained database identified patients undergoing laparoscopic cholecystectomy at a single academic center from 2013 to 2019. Exclusion criteria were primary open and single incision cholecystectomy. Patient factors included age, sex, BMI, and Charlson Comorbidity Index. Outcomes included operative time, conversion to open procedure, length of stay (LOS), mortality rate, and 30-day complications. A multivariable logistic regression was performed to determine independent predictors for open conversion.

RESULTS

A total of 1389 patients underwent laparoscopic cholecystectomy. 69.8% were female; mean age 48.6 years (range 15-94), average BMI 29.4 kg/m² (13.3-55.6). 989 patients (71.2%) underwent LC without fluorescence and 400 (28.8%) underwent FC with ICG. 30-day mortality detected 2 cases in the non-ICG group and zero with ICG. ICG reduced operative time by 26.47 min per case (p < 0.0001). For patients with BMI ≥ 30 kg/m², operative duration for ICG vs non-ICG groups was 75.57 vs 104.9 min respectively (p < 0.0001). ICG required conversion to open at a rate of 1.5%, while non-ICG converted at a rate of 8.5% (p < 0.0001). Conversion rate remained significant with multivariable analysis (OR 0.212, p = 0.001). A total of 19 cases were aborted (1.35%), 8 in the ICG group (1.96%) and 11 in the non-ICG group (1.10%), these cases were not included in LC totals. Average LOS was 0.69 vs 1.54 days in the ICG compared to non-ICG LCs (p < 0.0001), respectively. Injuries were more common in the non-ICG group, with 9 patients sustaining Strasberg class A injuries in the non-ICG group and 2 in the ICG group. 1 CBDI occurred in the non-ICG group. There was no significant difference in 30-day complication rates between groups.

CONCLUSION

ICG cholangiography is a non-invasive adjunct to laparoscopic cholecystectomy, leading to improved patient outcomes with respect to operative times, decreased conversion to open procedures, and shorter length of hospitalization. Fluorescence cholangiography improves visualization of biliary anatomy, thereby decreasing rate of CBDI, Strasberg A injuries, and mortality. These findings support ICG as standard of care during laparoscopic cholecystectomy.

Combined fluorescence-guided surgery and photodynamic therapy for glioblastoma multiforme using cyanine and chlorin nanocluster

INTRODUCTION

Glioblastoma multiforme (GBM) is the most common primary intracranial malignancy; survival can be improved by maximizing the extent-of-resection.

METHODS

A near-infrared fluorophore (Indocyanine-Green, ICG) was combined with a photosensitizer (Chlorin-e6, Ce6) on the surface of superparamagnetic-iron-oxide-nanoparticles (SPIONs), all FDA-approved for clinical use, yielding a nanocluster (ICS) using a microemulsion. The physical-chemical properties of the ICS were systematically evaluated. Efficacy of photodynamic therapy (PDT) was evaluated in vitro with GL261 cells and in vivo in a subtotal resection trial using a syngeneic flank tumor model. NIR imaging properties of ICS were evaluated in both a flank and an intracranial GBM model.

RESULTS

ICS demonstrated high ICG and Ce6 encapsulation efficiency, high payload capacity, and chemical stability in physiologic conditions. In vitro cell studies demonstrated significant PDT-induced cytotoxicity using ICS. Preclinical animal studies demonstrated that the nanoclusters can be detected through NIR imaging in both flank and intracranial GBM tumors (ex: 745 nm, em: 800 nm; mean signal-to-background 8.5 ± 0.6). In the flank residual tumor PDT trial, subjects treated with PDT demonstrated significantly enhanced local control of recurrent neoplasm starting on postoperative day 8 (23.1 mm3 vs 150.5 mm3, p = 0.045), and the treatment effect amplified to final mean volumes of 220.4 mm3 vs 806.1 mm3 on day 23 (p = 0.0055).

CONCLUSION

A multimodal theragnostic agent comprised solely of FDA-approved components was developed to couple optical imaging and PDT. The findings demonstrated evidence for the potential theragnostic benefit of ICS in surgical oncology that is conducive to clinical integration.

Facile formulation of a long-wavelength cyanine for optical imaging in the second near-infrared window

The second near-infrared window (NIR-II) beyond 1000 nm has attracted attention for optical contrast imaging in small animals. We sought to assess whether commercially available NIR-II dyes could be easily formulated for this purpose. 13 hydrophobic NIR-II dyes were purchased and screened by formulating them in simple solubilizing agents with established use in humans: propylene glycol, Cremaphor EL, Kolliphor HS15 (HS15), Tween 80, and cyclodextrin. Based on the absorption at 1064 nm (matching the Nd:YAG laser output commonly used in photoacoustic imaging), three of the dyes were further assessed at varying dye and surfactant concentrations. Of these, benzo indole butyl diphenylaminocyclopentene heptamethine (BIBDAH) tetrafluoroborate in HS15 generally showed the most favorable NIR-II character. 1 mg mL-1 BIBDAH in 25% HS15 exhibited a single absorption peak at 1030 nm with a calculated intensity greater than 100, which was relatively stable for weeks in storage. Following intravenous administration to mice, determination of BIBDAH pharmacokinetics was possible by absorption measurements of sampled plasma, revealing a circulating half-life of about one hour. Most of the dye was taken up by the liver. BIBDAH was used in vitro and in vivo as a photoacoustic contrast imaging agent and its accumulation could be detected in subcutaneous tumors in mice. BIBDAH was used for fluorescence imaging of blood vessels in mice, including in the brain (through intact skull), and dye clearance from blood to the liver was visualized. Taken together, this study confirms that accessible, strongly-absorbing dye can readily be formulated for injection by simply dissolving them in biocompatible surfactants and used for high-contrast preclinical optical imaging in the second NIR window.

Thermally sensitive fluorescence imaging system for radiofrequency ablation guidance

Radiofrequency ablation (RFA) has been clinically used as a minimally invasive procedure for the treatment of many solid tumors. However, the current imaging techniques have some shortages in RFA guidance, especially for the assessment of the margin of ablation. Herein, we developed a novel optical imaging platform to guide RFA utilizing fluorescence resonance energy transfer from a thermally sensitive fluorescent protein conjugated to a near-infrared fluorescent dye. Additionally, attaching receptor-targeting ligands further equipped the system with high specificity to tumors overexpressing the targeted receptor.

Extrahepatic cholangiography in near-infrared II window with the clinically approved fluorescence agent indocyanine green: a promising imaging technology for intraoperative diagnosis

Rationale: Biliary tract injury remains the most dreaded complication during laparoscopic cholecystectomy. New intraoperative guidance technologies, including near-infrared (NIR) fluorescence cholangiography with indocyanine green (ICG), are under comprehensive evaluation. Previous studies had shown the limitations of traditional NIR light (NIR-I, 700-900 nm) in visualizing the biliary tract structures in specific clinical situations. The aim of this study was to evaluate the feasibility of performing the extrahepatic cholangiography in the second NIR window (NIR-II, 900-1700 nm) and compare it to the conventional NIR-I imaging. Methods: The absorption and emission spectra, as well as fluorescence intensity and photostability of ICG-bile solution in the NIR-II window were recorded and measured. In vitro intralipid® phantom imaging was performed to evaluate tissue penetrating depth in NIR-I and NIR-II window. Different clinical scenarios were modeled by broadening the penetration distance or generating bile duct injuries, and bile duct visualization and lesion site diagnosis in the NIR-II window were evaluated and compared with NIR-I imaging. Results: The fluorescence spectrum of ICG-bile solution extends well into the NIR-II region, exhibiting intense emission value and excellent photostability sufficient for NIR-II biliary tract imaging. Extrahepatic cholangiography using ICG in the NIR-II window obviously reduced background signal and enhanced penetration depth, providing more structural information and improved visualization of the bile duct or lesion location in simulated clinical scenarios, outperforming the NIR-I window imaging. Conclusions: The conventional clinically approved agent ICG is an excellent fluorophore for NIR-II bile duct imaging. Fluorescence cholangiography with ICG in the NIR-II window could provide adequate visualization of the biliary tract structures with increased resolution and penetration depth and might be a valid option to increase the safety of cholecystectomy in difficult cases.

Multifunctional Nanorobot System for Active Therapeutic Delivery and Synergistic Chemo-photothermal Therapy

Nanorobots are safe and exhibit powerful functionalities, including delivery, therapy, and diagnosis. Therefore, they are in high demand for the development of new cancer therapies. Although many studies have contributed to the progressive development of the nanorobot system for anticancer drug delivery, these systems still face some critical limitations, such as potentially toxic materials in the nanorobots, unreasonable sizes for passive targeting, and the lack of several essential functions of the nanorobot for anticancer drug delivery including sensing, active targeting, controlling drug release, and sufficient drug loading capacity. Here, we developed a multifunctional nanorobot system capable of precise magnetic control, sufficient drug loading for chemotherapy, light-triggered controlled drug release, light absorption for photothermal therapy, enhanced magnetic resonance imaging, and tumor sensing. The developed nanorobot system exhibits an in vitro synergetic antitumor effect of photothermal therapy and chemotherapy and outstanding tumor-targeting efficiency in both in vitro and in vivo environments. The results of this study encourage further explorations of an efficient active drug delivery system for cancer treatment and the development of nanorobot systems for other biomedical applications.

Perfect Registration Leads to Imperfect Performance: A Randomized Trial of Multimodal Intraoperative Image Guidance

OBJECTIVE

To compare surgical safety and efficiency of 2 image guidance modalities, perfect augmented reality (AR) and side-by-side unregistered image guidance (IG), against a no guidance control (NG), when performing a simulated laparoscopic cholecystectomy (LC).

BACKGROUND

Image guidance using AR offers the potential to improve understanding of subsurface anatomy, with positive ramifications for surgical safety and efficiency. No intra-abdominal study has demonstrated any advantage for the technology. Perfect AR cannot be provided in the operative setting in a patient; however, it can be generated in the simulated setting.

METHODS

Thirty-six experienced surgeons performed a baseline LC using the LapMentor simulator before randomization to 1 of 3 study arms: AR, IG, or NG. Each performed 3 further LC. Safety and efficiency-related simulator metrics, and task workload (SURG-TLX) were collected.

RESULTS

The IG group had a shorter total instrument path length and fewer movements than NG and AR groups. Both IG and NG took a significantly shorter time than AR to complete dissection of Calot triangle. Use of IG and AR resulted in significantly fewer perforations and serious complications than the NG group. IG had significantly fewer perforations and serious complications than the AR group. Compared with IG, AR guidance was found to be significantly more distracting.

CONCLUSION

Side-by-side unregistered image guidance (IG) improved safety and surgical efficiency in a simulated setting when compared with AR or NG. IG provides a more tangible opportunity for integrating image guidance into existing surgical workflow as well as delivering the safety and efficiency benefits desired.

Applications of near infrared and surface enhanced Raman scattering techniques in tumor imaging: A short review

Imaging technologies play a vital role in clinical oncology and have undergone massive growth over the past few decades. Research in the field of tumor imaging and biomedical diagnostics requires early detection of physiological alterations so as to provide curative treatment in real time. The objective of this review is to provide an insight about near infrared fluorescence (NIRF) and surface enhanced Raman scattering (SERS) imaging techniques that can be used to expand their capabilities for the early detection and diagnosis of cancer cells. Basic setup, principle and working of the instruments has been provided and common NIRF imaging agents as well as SERS tags are also discussed besides the analytical advantages/disadvantages of these techniques. This review can help researchers working in the field of molecular imaging to design cost effective fluorophores and SERS tags to overcome the limitations of both NIRF as well as SERS imaging technologies.

A 25 micron-thin microscope for imaging upconverting nanoparticles with NIR-I and NIR-II illumination

Rationale: Intraoperative visualization in small surgical cavities and hard-to-access areas are essential requirements for modern, minimally invasive surgeries and demand significant miniaturization. However, current optical imagers require multiple hard-to-miniaturize components including lenses, filters and optical fibers. These components restrict both the form-factor and maneuverability of these imagers, and imagers largely remain stand-alone devices with centimeter-scale dimensions. Methods: We have engineered INSITE (Immunotargeted Nanoparticle Single-Chip Imaging Technology), which integrates the unique optical properties of lanthanide-based alloyed upconverting nanoparticles (aUCNPs) with the time-resolved imaging of a 25-micron thin CMOS-based (complementary metal oxide semiconductor) imager. We have synthesized core/shell aUCNPs of different compositions and imaged their visible emission with INSITE under either NIR-I and NIR-II photoexcitation. We characterized aUCNP imaging with INSITE across both varying aUCNP composition and 980 nm and 1550 nm excitation wavelengths. To demonstrate clinical experimental validity, we also conducted an intratumoral injection into LNCaP prostate tumors in a male nude mouse that was subsequently excised and imaged with INSITE. Results: Under the low illumination fluences compatible with live animal imaging, we measure aUCNP radiative lifetimes of 600 μs - 1.3 ms, which provides strong signal for time-resolved INSITE imaging. Core/shell NaEr0.6Yb0.4F4 aUCNPs show the highest INSITE signal when illuminated at either 980 nm or 1550 nm, with signal from NIR-I excitation about an order of magnitude brighter than from NIR-II excitation. The 55 μm spatial resolution achievable with this approach is demonstrated through imaging of aUCNPs in PDMS (polydimethylsiloxane) micro-wells, showing resolution of micrometer-scale targets with single-pixel precision. INSITE imaging of intratumoral NaEr0.8Yb0.2F4 aUCNPs shows a signal-to-background ratio of 9, limited only by photodiode dark current and electronic noise. Conclusion: This work demonstrates INSITE imaging of aUCNPs in tumors, achieving an imaging platform that is thinned to just a 25 μm-thin, planar form-factor, with both NIR-I and NIR-II excitation. Based on a highly paralleled array structure INSITE is scalable, enabling direct coupling with a wide array of surgical and robotic tools for seamless integration with tissue actuation, resection or ablation.

Efficiency of fluorescent cholangiography during laparoscopic cholecystectomy for subvesical bile ducts: A case report

•

The subvesical bile ducts are important from the potential risk for bile leakage.

•

It is difficult to identify the subvesical bile ducts intraoperatively.

•

Fluorescent cholangiography visualized the subvesical bile ducts clearly.

Introduction

The subvesical bile ducts are located in the peri-hepatic connective tissue of the gallbladder fossa. Injury of the subvesical bile ducts provokes the severe complication of bile leak. Until now, fluorescent cholangiography has been employed during hepatobiliary surgery. Herein, we report the detection of subvesical bile ducts by fluorescent cholangiography during laparoscopic cholecystectomy.

Presentation of case

A 63-year-old female was admitted to our department for surgery for symptomatic cholelithiasis. The subvesical bile ducts were not observed on drip-infusion cholangiography with computed tomography. Immediately following induction of anesthesia, 2.5 mg of indocyanine green was intravenously injected. Fluorescent cholangiography demonstrated two thin aberrant bile ducts during dissection of Calot’s triangle. We considered them to be subvesical bile ducts. We ligated them with clips, divided them, and then performed laparoscopic cholecystectomy using a standard procedure. The patient had a good post-operative recovery without bile leakage. Postoperative laboratory test results were all within normal limits. Computed tomography revealed no dilatation of the intrahepatic bile duct after laparoscopic cholecystectomy. The patient was discharged on postoperative day 4.

Discussion

Injury to the subvesical bile ducts is one of the most common causes of bile leakage associated with cholecystectomy. Fluorescent cholangiography enabled real-time identification of the thin subvesical bile ducts, which were undetectable by drip-infusion cholangiography with computed tomography.

Conclusion

Fluorescent cholangiography during laparoscopic cholecystectomy may be useful for preventing postoperative bile leakage.

Sentinel lymph node mapping using indocyanine green in patients with uterine and cervical neoplasms: restrictions of the method

Purpose

To establish the surgical, demographic and histopathological factors associated with inaccurate sentinel lymph nodes (SLNs) identification using indocyanine green (ICG) and near-infrared (NIR) fluorescence imaging in uterine and cervical neoplasms during both open and laparoscopic surgery.

Methods

We reviewed patients with atypical endometrial hyperplasia (AEH), clinical stage I and II cervical cancer or uterine malignancies who underwent primary surgery with SLN mapping between September 2015 and January 2018. An analysis of patients’ demographics, tumor factors and surgical approach was conducted. Bilateral and overall detection rates were calculated and univariate analysis was performed to estimate factors associated with failed SLN mapping.

Results

A total of 32 patients with uterine and cervical neoplasms were included in the study. The overall detection rate of the SLN was 84% and bilateral detection rate was 75%. There were no statistically relevant differences in overall and bilateral SLN detection rates by BMI, surgical approach or age. Regarding endometrial cancer, there were no differences in SLN detection rates when comparing tumor grade, histology nor myometrial invasion. For SLN detection failure, only the presence of metastatic lymph nodes and lack of surgical experience significantly increased the disability to detect SLNs (p = 0.03, p = 0.04, respectively).

Conclusions

SLN mapping technique using NIR fluorescence imaging with ICG appears to be accurate method in most of the patients with cervical or endometrial carcinoma, regardless of demographic characteristics, tumor-related features and surgical approach. Surgeons’ expertise in that field allows obtaining excellent detection rates.

Robotic (super) microsurgery: Feasibility of a new master-slave platform in an in vivo animal model and future directions

Advanced microsurgical procedures are currently limited by human precision and manual dexterity. The potential of robotics in microsurgery is highlighted, including a general overview of applications of robotic assistance in microsurgery and its introduction in different surgical specialties. A new robotic platform especially designed for (super) microsurgery is presented. Results of an in vivo animal study underline its feasibility and encourage further development toward clinical studies. Future directions of robotic microsurgery are proposed.

Upcoming imaging concepts and their impact on treatment planning and treatment response in radiation oncology

For 2018, the American Cancer Society estimated that there would be approximately 1.7 million new diagnoses of cancer and about 609,640 cancer-related deaths in the United States. By 2030 these numbers are anticipated to exceed a staggering 21 million annual diagnoses and 13 million cancer-related deaths. The three primary therapeutic modalities for cancer treatments are surgery, chemotherapy, and radiation therapy. Individually or in combination, these treatment modalities have provided and continue to provide curative and palliative care to the myriad victims of cancer.

Today, CT-based treatment planning is the primary means through which conventional photon radiation therapy is planned. Although CT remains the primary treatment planning modality, the field of radiation oncology is moving beyond the sole use of CT scans to define treatment targets and organs at risk. Complementary tissue scans, such as magnetic resonance imaging (MRI) and positron electron emission (PET) scans, have all improved a physician’s ability to more specifically identify target tissues, and in some cases, international guidelines have even been issued. Moreover, efforts to combine PET and MR to define solid tumors for radiotherapy planning and treatment evaluation are also gaining traction.

Keeping these advances in mind, we present brief overviews of other up-and-coming key imaging concepts that appear promising for initial treatment target definition or treatment response from radiation therapy.

Evaluation of laparoscopic cholecystectomy using indocyanine green cholangiography including cholecystitis: A retrospective study

Intraoperative cholangiography involving the excretion of fluorescent indocyanine green (ICG) into the bile is used to determine biliary anatomy in laparoscopic cholecystectomy (LC). This study aimed to evaluate the features of intraoperative ICG cholangiography, in LC with cholecystitis, and compared the delineation of the cystic duct (CD) between ICG cholangiography and magnetic resonance cholangiopancreatography (MRCP).Participants comprised 65 patients undergoing LC using ICG cholangiography.Fifty-eight patients (89.2%) were diagnosed with gallbladder stones and 32 (49.2%) with acute cholecystitis. ICG cholangiography identified CD in 54 patients (83.1%) and did not identify CD in 11 patients (16.9%). The mean value of the fluorescence intensity in the identified CD group by ICG cholangiography was 87.6 ± 31.5 arbitrary unit and that in the not identified CD group by ICG cholangiography was 24.4 ± 10.1 arbitrary unit (P < .001). Compared with the patients in the identified CD group, those in the not identified CD group had higher incidence of acute cholecystitis (P < .001), and higher conversion rates (P = .003). A correlation between the delineation of CD by ICG cholangiography and MRCP was analyzed, and it revealed a correlation between each other (P = .002)Inflammation had harmful effects with regard to the passing of CD. If we can identify CD or common bile duct with ICG cholangiography, we may be able to perform LC with confidence, even in the presence of severe inflammation.

Potential of near-infrared fluorescence image-guided debridement in trauma surgery

This case report presents the use of near-infrared fluorescence (NIRF) imaging using indocyanine green (ICG) and its potential for the evaluation of soft tissue viability in a traumatic case. Standard implementation of this novel imaging modality might decrease the number of surgical debridement procedures in complex traumatic wounds.

Optimizing the image of fluorescence cholangiography using ICG: a systematic review and ex vivo experiments

Background

Though often only briefly described in the literature, there are clearly factors that have an influence on the fluorescence intensity, and thereby the usefulness of the technique. This article aims to provide an overview of the factors influencing the fluorescence intensity of fluorescence imaging with Indocyanine green, primarily focussed on NIRF guided cholangiography.

Methods

A systematic search was conducted to gain an overview of currently used methods in NIRF imaging in laparoscopic cholecystectomies. Relevant literature was searched to gain advice on what methods to use. Ex vivo experiments were performed to assess various factors that influence fluorescence intensity and whether the found clinical advices can be confirmed.

Results

ICG is currently the most widely applied fluorescent dye. Optimal ICG concentration lies between 0.00195 and 0.025 mg/ml, and this dose should be given as early as achievable—but maximum 24 h—before surgery. When holding the laparoscope closer and perpendicular to the dye, the signal is most intense. In patients with a higher BMI and/or cholecystitis, fluorescence intensity is lower, but NIRF seems to be more helpful. There are differences between various marketed fluorescence systems. Also, no uniform method to assess fluorescence intensity is available yet.

Conclusions

This study identified and discussed several factors that influence the signal of fluorescence cholangiography. These factors should be taken into account when using NIRF cholangiography. Also, surgeons should be aware of new dyes and clinical systems, in order to benefit most from the potential of NIRF imaging.

Electronic supplementary material

The online version of this article (10.1007/s00464-018-6233-x) contains supplementary material, which is available to authorized users.

Near-infrared fluorescence image-guidance in plastic surgery: A systematic review

Background

Near-infrared fluorescence (NIRF) imaging technique, after administration of contrast agents with fluorescent characteristics in the near-infrared (700–900 nm) range, is considered to possess great potential for the future of plastic surgery, given its capacity for perioperative, real-time anatomical guidance and identification. This study aimed to provide a comprehensive literature review concerning current and potential future applications of NIRF imaging in plastic surgery, thereby guiding future research.

Methods

A systematic literature search was performed in databases of Cochrane Library CENTRAL, MEDLINE, and EMBASE (last search Oct 2017) regarding NIRF imaging in plastic surgery. Identified articles were screened and checked for eligibility by two authors independently.

Results

Forty-eight selected studies included 1166 animal/human subjects in total. NIRF imaging was described for a variety of (pre)clinical applications in plastic surgery. Thirty-two articles used NIRF angiography, i.e., vascular imaging after intravenous dye administration. Ten articles reported on NIRF lymphography after subcutaneous dye administration. Although currently most applied, general protocols for dosage and timing of dye administration for NIRF angiography and lymphography are still lacking. Three articles applied NIRF to detect nerve injury, and another three studies described other novel applications in plastic surgery.

Conclusions

Future standard implementation of novel intraoperative optical techniques, such as NIRF imaging, could significantly contribute to perioperative anatomy guidance and facilitate critical decision-making in plastic surgical procedures. Further investigation (i.e., large multicenter randomized controlled trials) is mandatory to establish the true value of this innovative surgical imaging technique in standard clinical practice and to aid in forming consensus on protocols for general use.

Level of Evidence: Not ratable

Delineation of retroperitoneal metastatic lymph nodes in ovarian cancer with near-infrared fluorescence imaging

Lymph node metastasis occurs in early-stage and late-stage ovarian cancers. Systematic lymphadenectomy is frequently conducted in an attempt to prevent disease progression. However, this method is associated with multiple complications. Therefore, it is necessary to develop a less invasive and more sensitive method for detecting lymphatic metastasis in ovarian cancer. The aim of the present study was to develop an appropriate fluorescent label for the analysis of lymphatic metastasis in vivo. To this end, epithelial ovarian cancer cells with high potential for lymph node metastasis were labeled using mCherry fluorescence. The cells were then imaged in vitro to determine the expression of mCherry, and in a mouse xenograft model in vivo. The data demonstrated the successful identification of metastatic retroperitoneal lymph nodes by co-localization with lymph nodes labeled by near-infrared fluorescence nanoparticles in vivo. These data provided important insights into the further development of methods for intra-operative identification of lymphatic metastasis and the mechanisms underlying lymphatic metastasis.

Optical Characteristics and Tumor Imaging Capabilities of Near Infrared Dyes in Free and Nano-Encapsulated Formulations Comprised of Viral Capsids

Near infrared (NIR) fluorescent molecules and nanosized structures can serve as potential optical probes for image-guided removal of small tumor nodules (≲ 1 mm diameter). Although indocyanine green (ICG) remains as the only FDA-approved NIR dye, other organic dyes are under extensive development for enhanced imaging capabilities. One such dye is BrCy106-NHS where bromine is substituted for aromatic structures in cyanine dyes. Herein, we investigate the absorption and fluorescence characteristics of ICG and BrCy106-NHS, and quantitatively assess their tumor imaging capabilities in free (non-encapsulated) and a nano-encapsulated form that utilizes the capsid protein (CP) from genome-depleted plant-infecting brome mosaic virus as the encapsulating shell. We refer to these nanoconstructs as optical viral ghosts (OVGs). For example, when fabricated at CP to dye concentration ratio of 200, value of the spectrally integrated fluorescence emission for BrCy106-NHS-doped OVGs is ∼60 times higher than that of ICG-doped OVGs. Our analysis of homogenized mice intraperitoneal tumors indicate that the averaged total fluorescence emission associated with the use of BrCy106-NHS-doped can be at least about 44 times greater than that of ICG-doped OVGs. Our results suggest that OVGs containing BrCy106-NHS may potentially serve as effective optical probes for tumor imaging.

Beyond the margins: real-time detection of cancer using targeted fluorophores

Over the past two decades, synergistic innovations in imaging technology have resulted in a revolution in which a range of biomedical applications are now benefiting from fluorescence imaging. Specifically, advances in fluorophore chemistry and imaging hardware, and the identification of targetable biomarkers have now positioned intraoperative fluorescence as a highly specific real-time detection modality for surgeons in oncology. In particular, the deeper tissue penetration and limited autofluorescence of near-infrared (NIR) fluorescence imaging improves the translational potential of this modality over visible-light fluorescence imaging. Rapid developments in fluorophores with improved characteristics, detection instrumentation, and targeting strategies led to the clinical testing in the early 2010s of the first targeted NIR fluorophores for intraoperative cancer detection. The foundations for the advances that underline this technology continue to be nurtured by the multidisciplinary collaboration of chemists, biologists, engineers, and clinicians. In this Review, we highlight the latest developments in NIR fluorophores, cancer-targeting strategies, and detection instrumentation for intraoperative cancer detection, and consider the unique challenges associated with their effective application in clinical settings.

Long wavelength excitable near-infrared fluorescent nanoparticles with aggregation-induced emission characteristics for image-guided tumor resection

Near infrared (NIR) fluorescence imaging (700-900 nm) is a promising technology in preclinical and clinical tumor diagnosis and therapy. The availability of excellent NIR fluorescent contrast agents is still the main barrier to implementing this technology. Herein, we report the design and synthesis of two series of NIR fluorescent molecules with long wavelength excitation and aggregation-induced emission (AIE) characteristics by fine-tuning their molecular structures and substituents. Further self-assembly between an amphiphilic block co-polymer and the obtained AIE molecules leads to AIE nanoparticles (AIE NPs), which have absorption maxima at 635 nm and emission maxima between 800 and 815 nm with quantum yields of up to 4.8% in aggregated states. In vitro and in vivo toxicity results demonstrate that the synthesized AIE NPs are biocompatible. Finally, the synthesized AIE NPs have been successfully used for image-guided tumor resection with a high tumor-to-normal tissue signal ratio of 7.2.

Near-infrared fluorescence laparoscopy of the cystic duct and cystic artery: first experience with two new preclinical dyes in a pig model

Background

Imaging techniques that enhance visualisation of the anatomy may help prevent bile duct injury. Near-Infrared Fluorescence Imaging is such a technique. Previous experiments with ICG have shown that illumination of the extra-hepatic bile ducts is feasible. Yet, there is room for improvement in the visualisation of the target as compared to the background. Experiments with IRDye^® 800CW show promising results. However, this dye is too expensive for routine clinical use. The aim of this study is to test the first applicability of two newly developed preclinical dyes regarding intraoperative imaging of the cystic duct and cystic artery, compared with IRDye^® 800CW.

Methods

Laparoscopic cholecystectomy was performed in three pigs, using a laparoscopic fluorescence imaging system. Each pig received 6 mg of one of the fluorescent dyes (1 mg/mL; IRDye^® 800CW, IRDye^® 800BK or IRDye^® 800NOS) by intravenous injection. Intraoperative recognition of the biliary system and cystic artery was registered at set time points. All procedures were digitally recorded, and the target to background ratio (TBR) was determined to assess the fluorescence signal.

Results

With all three fluorescent dyes, the cystic artery was directly visualised. For the visualisation of the cystic duct, 15, 34 and 30 min were needed using IRDye^® 800BK, IRDye^® 800NOS and IRDye^® 800CW, respectively. The maximum TBR of the cystic duct was the highest with IRDye^® 800NOS (4.20) after 36 min, compared to 2.45 for IRDye^® 800BK and 2.15 for IRDye^® 800CW, both after 45 min. There were no adverse events.

Conclusion

IRDye^® 800BK and IRDye^® 800NOS seem to be good alternatives for IRDye^® 800CW for the visualisation of the cystic duct and cystic artery in pigs.

Vision 20/20: Molecular-guided surgical oncology based upon tumor metabolism or immunologic phenotype: Technological pathways for point of care imaging and intervention

Surgical guidance with fluorescence has been demonstrated in individual clinical trials for decades, but the scientific and commercial conditions exist today for a dramatic increase in clinical value. In the past decade, increased use of indocyanine green based visualization of vascular flow, biliary function, and tissue perfusion has spawned a robust growth in commercial systems that have near-infrared emission imaging and video display capabilities. This recent history combined with major preclinical innovations in fluorescent-labeled molecular probes, has the potential for a shift in surgical practice toward resection guidance based upon molecular information in addition to conventional visual and palpable cues. Most surgical subspecialties already have treatment management decisions partially based upon the immunohistochemical phenotype of the cancer, as assessed from molecular pathology of the biopsy tissue. This phenotyping can inform the surgical resection process by spatial mapping of these features. Further integration of the diagnostic and therapeutic value of tumor metabolism sensing molecules or immune binding agents directly into the surgical process can help this field mature. Maximal value to the patient would come from identifying the spatial patterns of molecular expression in vivo that are well known to exist. However, as each molecular agent is advanced into trials, the performance of the imaging system can have a critical impact on the success. For example, use of pre-existing commercial imaging systems are not well suited to image receptor targeted fluorophores because of the lower concentrations expected, requiring orders of magnitude more sensitivity. Additionally the imaging system needs the appropriate dynamic range and image processing features to view molecular probes or therapeutics that may have nonspecific uptake or pharmacokinetic issues which lead to limitations in contrast. Imaging systems need to be chosen based upon objective performance criteria, and issues around calibration, validation, and interpretation need to be established before a clinical trial starts. Finally, as early phase trials become more established, the costs associated with failures can be crippling to the field, and so judicious use of phase 0 trials with microdose levels of agents is one viable paradigm to help the field advance, but this places high sensitivity requirements on the imaging systems used. Molecular-guided surgery has truly transformative potential, and several key challenges are outlined here with the goal of seeing efficient advancement with ideal choices. The focus of this vision 20/20 paper is on the technological aspects that are needed to be paired with these agents.

Sensitivity and negative predictive value for sentinel lymph node biopsy in women with early-stage cervical cancer

OBJECTIVE

The role of sentinel lymph node (SLN) biopsy alone for staging of early-stage cervical cancer remains controversial. We aimed to determine the validity of this technique in women with early-stage cervical cancer.

METHODS

We retrospectively reviewed women with early-stage cervical cancer who underwent SLN mapping followed by complete pelvic lymphadenectomy as part of initial surgical management from August 1997 through October 2015. All modes of surgical approach were included. Lymphatic mapping was performed using blue dye, technetium-99m sulfur colloid (Tc-99), and/or indocyanine green (ICG). We determined SLN detection rates, sensitivity and negative predictive value.

RESULTS

One hundred eighty-eight patients were included, and 35 (19%) had lymph node metastases. At least one SLN was identified in 170 patients (90%), and bilateral SLNs were identified in 117 patients (62%). The majority of SLNs (83%) were found in the pelvis. There was no difference in detection rates between mapping agents, surgical approach, patients with and without prior conization or between patients with tumors <2cm and ≥2cm. The detection rate for bilateral SLNs was significantly lower in women with body mass index (BMI)>30kg/m² than in women with lower BMI (p=0.03). Metastatic disease in sentinel nodes was detected by H&E staining in 78% of cases and required ultrastaging/immunohistochemistry in 22% of cases. Only one patient had a false-negative result, yielding a sensitivity of 96.4% (95% CI 79.8%-99.8%) and negative predictive value of 99.3% (95% CI 95.6%-100%). The false-negative rate was 3.6%.

CONCLUSIONS

In these women with early-stage cervical cancer, SLN biopsy had very high sensitivity and negative predictive value. We believe it is time to change the standard of care for women with early-stage cervical cancer to SLN biopsy only.

Combination of Fluorescence-Guided Surgery With Photodynamic Therapy for the Treatment of Cancer

Specific visualization of body parts is needed during surgery. Fluorescence-guided surgery (FGS) uses a fluorescence contrast agent for in vivo tumor imaging to detect and identify both malignant and normal tissues. There are several advantages and clinical benefits of FGS over other conventional medical imaging modalities, such as its safety, effectiveness, and suitability for real-time imaging in the operating room. Recent advancements in contrast agents and intraoperative fluorescence imaging devices have led to a greater potential for intraoperative fluorescence imaging in clinical applications. Photodynamic therapy (PDT) is an alternative modality to treat tumors, which uses a light-sensitive drug (photosensitizers) and special light to destroy the targeted tissues. In this review, we discuss the fluorescent contrast agents, some newly developed imaging devices, and the successful clinical application of FGS. Additionally, we present the combined strategy of FGS with PDT to further improve the therapeutic effect for patients with cancer. Taken together, this review provides a unique perspective and summarization of FGS.

Indocyanine green fluorescence imaging in hepatobiliary surgery

Indocyanine green (ICG) is a fluorescent dye that has been widely used for fluorescence imaging during hepatobiliary surgery. ICG is injected intravenously, selectively taken up by the liver, and then secreted into the bile. The catabolism and fluorescence properties of ICG permit a wide range of visualization methods in hepatobiliary surgery. We have characterized the applications of ICG during hepatobiliary surgery into: 1) liver mapping, 2) cholangiography, 3) tumor visualization, and 4) partial liver graft evaluation. In this literature review, we summarize the current understanding of ICG use during hepatobiliary surgery. Intra-operative ICG fluorescence imaging is a safe, simple, and feasible method that improves the visualization of hepatobiliary anatomy and liver tumors. Intravenous administration of ICG is not toxic and avoids the drawbacks of conventional imaging. In addition, it reduces post-operative complications without any known side effects. ICG fluorescence imaging provides a safe and reliable contrast for extra-hepatic cholangiography when detecting intra-hepatic bile leakage following liver resection. In addition, liver tumors can be visualized and well-differentiated hepatocellular carcinoma tumors can be accurately identified. Moreover, vascular reconstruction and outflow can be evaluated following partial liver transplantation. However, since tissue penetration is limited to 5-10mm, deeper tissue cannot be visualized using this method. Many instances of false positive or negative results have been reported, therefore further characterization is required.

An Injectable, Click-Cross-Linked Small Intestinal Submucosa Drug Depot for the Treatment of Rheumatoid Arthritis

Here, a click-cross-linked small intestine submucosa (SIS) drug depot is described for the treatment of rheumatoid arthritis (RA). To the best of the knowledge, there have been no studies related to the intra-articular injection of methotrexate (Met)-loaded click-cross-linkable SIS (Met-loaded Cx-SIS) for RA treatment. As the key objective of this work, injectable formulations of tetrazine-modified SIS (TE-SIS) and transcyclooctene-modified SIS (TC-SIS) are employed as drug depots. Within a few seconds, the simple mixing of equal amounts of TE-SIS and TC-SIS suspensions forms a gelatinous click-cross-linked SIS (Cx-SIS) drug depot in vitro and in vivo. The formed Cx-SIS depot is maintained in the articular joint over an extended period, while SIS alone rapidly disappears. Injectable formulations of Met-loaded Cx-SIS and Met-loaded SIS are prepared and then injected into articular joints to form drug depots. Compared to animals treated with Met-loaded SIS, RA animals treated with Met-loaded Cx-SIS show effective RA repair, as well as extensive regeneration of chondrocytes and glycosaminoglycan deposits. Collectively, these results indicate that the Met-loaded Cx-SIS depot is successfully formed after intra-articular injection of click-cross-linkable SIS, and that this formulation induces long-lasting Met release and allows Met to act effectively in the articular joint, resulting in RA repair.

Sentinel Lymph Node Biopsy in Cutaneous Melanoma: Standard and New Technical Procedures and Clinical Advances. A Systematic Review of the Literature

Melanoma is an important public health problem, and its incidence is increasing worldwide. The disease status of regional lymph nodes is the most important prognostic factor in early-stage melanoma patients. Sentinel lymph node biopsy (SLNB) was introduced in the early 1990s as a less invasive procedure than complete lymph node dissection to allow histopathologic evaluation of the "sentinel lymph node" (SLN), which is the first node along the lymphatic pathway from a primary tumor. Sentinel lymph node biopsy has minimal complication risks compared with standard complete lymph node dissection. Currently, SLNB is the accepted method for staging patients with clinically node-negative cutaneous melanoma and provides the most powerful prognostic information by evaluating the nodal basin status. The current practice of SLNB consists of the injection of Tc-labeled radiopharmaceutical, preoperative lymphoscintigraphy with the possibility of using the SPECT/CT hybrid imaging, and intraoperative SLN localization using a handheld gamma probe with or without the use of blue dye. Recently, the SLN localization and detection have been enhanced with the use of new tracers and new intraoperative devices, which have demonstrated to be particularly useful in melanomas of the head and neck region and in area of complex anatomy. Despite these important advances in the technology and the increasing experience in SLN mapping, major research centers have reported a false-negative rate higher than 15%. This relatively high false-negative rate, greater than those reported in the initial validation studies, points out the importance for the nuclear medicine community to continuously improve their knowledge on the biological behavior of melanoma and to improve the technical aspects that may allow more precise staging. For the SLNB procedure to be accurate, it is of critical importance that all "true" SLNs are identified and removed for examination. The aim of this article is to provide general information about the SLNB procedure in clinical practice highlighting the importance of standardization and accuracy of SLN identification in the light of the most recent technical innovations.