Nerve autofluorescence under near-ultraviolet light: cutting-edge technology for intra-operative neural tissue visualization in 17 patients

mRNA Expression of Mineralocorticoid and Glucocorticoid Receptors in Human and Mouse Sensory Neurons of the Dorsal Root Ganglia

BACKGROUND

Corticosteroid receptors, including mineralocorticoid receptor (MR) and glucocorticoid receptor (GR), play important roles in inflammatory pain in the dorsal root ganglion (DRG). Although it is widely known that activating the GR reduces inflammatory pain, it has recently been shown that MR activation contributes to pain and neuronal excitability in rodent studies. Moreover, little is known about the translation of this work to humans, or the mechanisms through which corticosteroid receptors regulate inflammatory pain.

METHODS

Corticosteroid receptor expression in human and mouse DRGs was characterized. RNAscope was used to perform high-resolution in situ hybridization for GR and MR mRNAs and to examine their colocalization with markers for nociceptors ( SCN10A , Na V 1.8 mRNA) and Aβ mechanoreceptors ( KCNS1 , Kv9.1 mRNA) in human DRG and C57BL/6J mouse DRG samples.

RESULTS

GR and MR mRNAs are expressed in almost all DRG neurons across species. The 2 receptors colocalize in 99.2% of human DRG neurons and 95.9% of mouse DRG neurons ( P = .0004, Fisher exact test). In both human and mouse DRGs, the large-diameter KCNS1+ Aβ mechanoreceptors showed a significantly higher MR/GR ratio (MR-leaning) compared to KCNS1- neurons (human: 0.23 vs 0.04, P = .0002; mouse: 0.35 vs -0.24, P < .0001; log ratios, unpaired t test), whereas small-diameter SCN10A+ nociceptive neurons showed a significantly lower MR/GR ratio (GR-leaning) compared to SCN10A- neurons (human: -0.02 vs 0.18, P = .0001; mouse: -0.16 vs 0.08, P < .0001; log ratios, unpaired t test).

CONCLUSIONS

These findings indicate that mouse corticosteroid receptor mRNA expression reflects human expression in the DRG, and that mice could be a suitable model for studying corticosteroid receptor involvement in pain. Additionally, this study supports the translatability of rodent data to humans for the use of more selective corticosteroids at the DRG in pain treatments.

Imaging Peripheral Nerves In Vivo with CT Neurogram Using Novel 2,4,6-Tri-Iodinated Lidocaine Contrast Agent

Peripheral nerve injuries are a significant concern in surgical procedures, often leading to chronic pain and functional impairment. Despite advancements in imaging, preoperative and intraoperative visualization of peripheral nerves remains a challenge. This study introduces and evaluates a novel tri-iodinated lidocaine-based contrast agent for computed tomography neurography, aiming to enhance the intraoperative visibility of peripheral nerves in vivo. A tri-iodinated lidocaine analogue was synthesized and characterized for its radiodensity, sodium channel binding and nerve affinity. Sodium channel affinity was performed using molecular docking. In vitro contrast enhancement was assessed by comparing the agent's Hounsfield unit (HU) values with those of Omnipaque, a clinically approved contrast medium. In vivo imaging was conducted on rat sciatic nerves using micro-CT, followed by ex vivo validation. Nerve conduction blockade was assessed via electrical stimulation and histological analysis was performed to evaluate neurotoxicity. Experimental results revealed the tri-iodinated lidocaine analogue to have similar or higher affinity toward voltage-gated sodium channels than the parent lidocaine and a radiodensity comparable to the commercial CT contrast agent Omnipaque in vitro. In vivo, the contrast agent provided CT visualization of the sciatic nerve, with a significant increase in HU values compared to untreated nerves. Electrical stimulation confirmed transient nerve conduction blockade without observable histological damage, supporting its dual role as an imaging and nerve-blocking agent. This study presents a novel tri-iodinated lidocaine-based contrast agent that enables clear CT visualization of peripheral nerves while maintaining reversible nerve inhibition. These findings support its potential application in preoperative planning and intraoperative nerve protection to reduce surgical nerve injuries. Further studies are warranted to optimize imaging conditions and evaluate its clinical feasibility.

Fluorescence-guided inguinal hernia repair with heightened nerve visualization to prevent chronic post-operative inguinal pain: Case report

INTRODUCTION

Iatrogenic injury to the ilioinguinal nerve and its branches during anterior inguinal hernia repair is a cause of chronic inguinal pain in up to 12 % of patients undergoing this operation. The risk of nerve injury is high, given the nerves' relatively small caliber and strictly-confined space through which they pass. In the current report, we describe using a novel fluorescence imaging system developed to detect nerve autofluorescence in a 66-year-old man who presented with a left-sided Type II inguinal hernia and underwent inguinal hernioplasty.

CASE PRESENTATION

Under general anesthesia, a left inguinal hernioplasty with mesh was performed using the Lichtenstein technique through an anterior approach. During surgery, a Dendrite® Imaging camera (Dendrite® Imaging, Germany) was employed to allow the surgical team to alternate freely between standard operating room (white) light and near-ultraviolet light (NUVL), specifically to enhance visualization of the ilioinguinal nerve and its branches. Under white light, neither the ilioinguinal nerve nor any of its branches were clearly visible. However, under NUVL, all fluoresced brightly and were easily avoided throughout the course of the hernia repair. The operation proceeded with no intraoperative or postoperative complications.

DISCUSSION

In this case, autofluorescence of the ilioinguinal nerve and its branches under NUVL utilizing a novel, hand-held fluorescent camera during hernia repair aided in their visualization and appeared to help prevent nerve injury.

CONCLUSION

New intraoperative technology that allows nerves to auto-fluoresce intra-operatively under NUVL warrants larger series and comparative trials to evaluate its efficacy at reducing iatrogenic nerve injury during inguinal hernioplasties.

Nerve autofluorescence to enhance nerve visualization during axillary lymph node dissection in three breast cancer patients: Case series

INTRODUCTION AND IMPORTANCE

Iatrogenic nerve injury is a possible complication of axillary lymph node dissection (ALND), which remains standard-of-care for some breast cancer patients. Recently, several studies have demonstrated that nerves auto-fluoresce in near-ultraviolet light (NUVL). We describe three women with BC in whom a recently-developed NUVL camera was used to facilitate visualization of and prevent iatrogenic injury to the intercostobrachial, long thoracic, and thoracodorsal nerves during ALND.

CASE PRESENTATION

In all three women, ALND was deemed necessary per current guidelines for the treatment of locally-advanced breast cancer following neoadjuvant chemotherapy. The surgery was performed using standard-of-care surgical techniques, except that a Dendrite® Imaging System was employed to visualize the surgical field both in white light and NUVL. In all patients, all nerves fluoresced brightly throughout their course in the surgical field. Such visualization was crucial during resection of lymph nodes close to nerves. No peri-operative complications occurred and no evidence of neurological injury was evident at one-month follow-up.

CLINICAL DISCUSSION

The Dendrite® Imaging System employs a NUVL light source and filter system to detect fluorescent signals emitted by neural tissue. These signals then pass through a filter system within the camera head, are captured by a chip, and are transmitted to a dedicated software platform for real-time analysis, processing, and relay to a display screen, allowing the surgical team to observe neural structures with clarity.

CONCLUSION

In three breast cancer patients undergoing ALND, nerve autofluorescence under NUVL aided in visualizing and preventing injury to all nerves within the surgical field.

Ultraviolet (UV) radiation: a double-edged sword in cancer development and therapy

It has long been widely acknowledged that ultraviolet (UV) light is an environment risk factor that can lead to cancer, particularly skin cancer. However, it is worth noting that UV radiation holds potential for cancer treatment as a relatively high-energy electromagnetic wave. With the help of nanomaterials, the role of UV radiation has caught increasing attention in cancer treatment. In this review, we briefly summarized types of UV-induced cancers, including malignant melanoma, squamous cell carcinoma, basal cell carcinoma, Merkel cell carcinoma. Importantly, we discussed the primary mechanisms underlying UV carcinogenesis, including mutations by DNA damage, immunosuppression, inflammation and epigenetic alterations. Historically limited by its shallow penetration depth, the introduction of nanomaterials has dramatically transformed the utilization of UV light in cancer treatment. The direct effect of UV light itself generally leads to the suppression of cancer cell growth and the initiation of apoptosis and ferroptosis. It can also be utilized to activate photosensitizers for reactive oxygen species (ROS) production, sensitize radiotherapy and achieve controlled drug release. Finally, we comprehensively weigh the significant risks and limitations associated with the therapeutic use of UV radiation. And the contradictory effect of UV exposure in promoting and inhibiting tumor has been discussed. This review provides clues for potential clinical therapy as well as future study directions in the UV radiation field. The precise delivery and control of UV light or nanomaterials and the wavelength as well as dose effects of UV light are needed for a thorough understanding of UV radiation.

Case report: Fluorescence-guided laparotomic radical prostatectomy with heightened nerve visualization

INTRODUCTION AND IMPORTANCE

Iatrogenic injury to the cavernous nerve and its branches results in post-operative erectile dysfunction in up to 85 % of men undergoing a radical prostatectomy. Here, we describe using a novel fluorescence-imaging system developed to detect nerve autofluorescence in a 66-year-old gentleman with prostate adenocarcinoma (Gleason Score 8 [4 + 4], prognostic group 4, indicating a highly-aggressive prostate cancer) who underwent laparotomic radical prostatectomy.

CASE PRESENTATION

Under general anesthesia, a laparotomic radical prostatectomy was performed using standard operative techniques. During surgery, a Dendrite imaging camera (Dendrite® Imaging, Germany) was employed to permit the surgical team to toggle freely between standard operating room (white) light and near-ultraviolet light (NUVL), with the specific purpose of enhancing visualization of the periprostatic nerve plexus, including the cavernous nerve and all its branches. Under white light, neither the cavernous nerve nor any of its branches were clearly visible. However, under NUVL, all fluoresced brightly and were easily avoided during prostate resection. Prostate resection proceeded with no intra-operative or post-operative complications. Moreover, upon one-month follow-up in the surgery clinic, the patient reported no erectile dysfunction, difficulties voiding, or other neurological or non-neurological complaints.

CLINICAL DISCUSSION

In this case, autofluorescence of the cavernous nerve and its branches during radical prostatectomy aided in their visualization and appeared to help prevent post-operative erectile dysfunction and all other potential neurological deficits.

CONCLUSION

Novel intra-operative technology enabling nerves to auto-fluoresce warrants larger series and comparative trials to assess its effectiveness reducing iatrogenic nerve injury during radical prostatectomies.

NIR-II light in clinical oncology: opportunities and challenges

Novel strategies utilizing light in the second near-infrared region (NIR-II; 900-1,880 nm wavelengths) offer the potential to visualize and treat solid tumours with enhanced precision. Over the past few decades, numerous techniques leveraging NIR-II light have been developed with the aim of precisely eliminating tumours while maximally preserving organ function. During cancer surgery, NIR-II optical imaging enables the visualization of clinically occult lesions and surrounding vital structures with increased sensitivity and resolution, thereby enhancing surgical quality and improving patient prognosis. Furthermore, the use of NIR-II light promises to improve cancer phototherapy by enabling the selective delivery of increased therapeutic energy to tissues at greater depths. Initial clinical studies of NIR-II-based imaging and phototherapy have indicated impressive potential to decrease cancer recurrence, reduce complications and prolong survival. Despite the encouraging results achieved, clinical translation of innovative NIR-II techniques remains challenging and inefficient; multidisciplinary cooperation is necessary to bridge the gap between preclinical research and clinical practice, and thus accelerate the translation of technical advances into clinical benefits. In this Review, we summarize the available clinical data on NIR-II-based imaging and phototherapy, demonstrating the feasibility and utility of integrating these technologies into the treatment of cancer. We also introduce emerging NIR-II-based approaches with substantial potential to further enhance patient outcomes, while also highlighting the challenges associated with imminent clinical studies of these modalities.

Nerve Visualization using Phenoxazine-Based Near-Infrared Fluorophores to Guide Prostatectomy

Fluorescence-guided surgery (FGS) is poised to revolutionize surgical medicine through near-infrared (NIR) fluorophores for tissue- and disease-specific contrast. Clinical open and laparoscopic FGS vision systems operate nearly exclusively at NIR wavelengths. However, tissue-specific NIR contrast agents compatible with clinically available imaging systems are lacking, leaving nerve tissue identification during prostatectomy a persistent challenge. Here, it is shown that combining drug-like molecular design concepts and fluorophore chemistry enabled the production of a library of NIR phenoxazine-based fluorophores for intraoperative nerve-specific imaging. The lead candidate readily delineated prostatic nerves in the canine and iliac plexus in the swine using the clinical da Vinci Surgical System that has been popularized for minimally invasive prostatectomy procedures. These results demonstrate the feasibility of molecular engineering of NIR nerve-binding fluorophores for ready integration into the existing surgical workflow, paving the path for clinical translation to reduce morbidity from nerve injury for prostate cancer patients.

Fluorescence imaging to visualize the recurrent laryngeal nerve during thyroidectomy procedures: analysis of 65 cases and 81 nerves

BACKGROUND

Recurrent laryngeal nerve (RLN) injury after thyroidectomy is relatively common. Locating the RLN prior to thyroid dissection is paramount to avoid injury. We developed a fluorescence imaging system that permits nerve autofluorescence. We aimed to determine the sensitivity and specificity of fluorescence imaging at detecting the RLN relative to thyroid and other background tissue and compared it to white light.

METHODS

In this prospective study, 65 patients underwent thyroidectomy from January to April 2022 (16 bilateral thyroid resections) using white and fluorescent light. Fluorescence intensity [relative fluorescence units (RFU)] was recorded for RLN, thyroid, and background. RFU mean, minimum, and maximum values were calculated using Image J software. Thirty randomly selected pairs of white and fluorescent light images were independently reviewed by two examiners to compare RLN detection rate, number of branches, and length and minimum width of nerves visualized. Parametric and nonparametric statistical analysis was performed.

RESULTS

All 81 RNLs observed were visualized more clearly under fluorescence (mean intensity, µ = 134.3 RFU) than either thyroid (µ = 33.7, p < 0.001) or background (µ = 14.4, p < 0.001). Forest plots revealed no overlap between RLN intensity and that of either other tissue. Sensitivity and specificity for RLN were 100%. All 30 RLNs and all 45 nerve branches were clearly visualized under fluorescence, versus 17 and 22, respectively, with white light (both p < 0.001). Visible nerve length was 2.5 × as great with fluorescence as with white light (µ = 1.90 vs. 0.76 cm, p < 0.001).

CONCLUSIONS

In 65 patients and 81 nerves, RLN detection was markedly and consistently enhanced with autofluorescence neuro-imaging during thyroidectomy, with 100% sensitivity and specificity.

Fluorescence Imaging to Identify and Preserve Fifth Intercostal Sensory Nerves during Bilateral Nipple-sparing Mastectomies

The use of nipple-sparing mastectomies has increased steadily over the past 10-15 years. However, one major source of patient dissatisfaction with both skin- and nipple-sparing mastectomies is lost skin and/or nipple sensation postoperatively due to intraoperative, iatrogenic sensory nerve injury. We summarize the case of a 41-year-old woman with BRCA(+) breast cancer who underwent bilateral, risk-reducing nipple-sparing mastectomies, immediately followed by bilateral, direct-to-implant breast reconstruction, in whom a prototype fluorescent imaging camera was used to facilitate sensory nerve identification and preservation. Preoperatively, tactile and thermal quantitative sensory testing were performed using a 30-gauge needle to determine baseline sensory function over both breasts. Then, nipple-sparing mastectomies and direct-to-implant reconstruction were performed. Using a laterally-displaced submammary approach, the anterior intercostal artery perforator neurovascular pedicle was preserved. Then a prototype camera, which emits near-ultraviolet light, was used to detect nerve autofluorescence. Intraoperatively under near-ultraviolet light, both the fifth intercostal nerve and its sensory branches auto-fluoresced clearly, so that surgery was completed without apparent injury to the fifth intercostal nerve or any of its branches. Postoperatively, the patient reported full sensory function throughout both breasts and both nipple-areolar complexes, which was confirmed on both tactile and thermal sensory testing at 3-month follow-up. The patient experienced no complications and rated her overall satisfaction with surgery on both breasts as 10 out of 10. To our knowledge, this is the first time sensory nerve auto-fluorescence has been reported to reduce the likelihood of intraoperative, iatrogenic nerve injury and preserve sensory function.

Efficacy of indocyanine green (ICG) fluorescent cholangiography to improve intra-operative visualization during laparoscopic cholecystectomy in pediatric patients: a comparative study between ICG-guided fluorescence and standard technique

BACKGROUND

In the last few years, indocyanine green (ICG) fluorescent cholangiography (FC) has been adopted to perform intra-operative biliary mapping during laparoscopic cholecystectomy (LC). This study aimed to compare the results of LC with and without use of ICG-FC.

METHODS

All LC operated from June 2017 to June 2021 in our unit were retrospectively reviewed. Pre-operative workup included ultrasonography to assess dilation of main biliary tree. The ICG dosage was 0.35 mg/kg and the median timing of administration was 15.5 h pre-operatively. We evaluated, analyzing videorecorded procedures, 3 parameters in both groups: the total operative time (T1), the time of cystic duct isolation, clipping and sectioning (T2), and the time of gallbladder removal from hepatic fossa (T3).

RESULTS

Forty-three LC were operated in the study period: 22 using standard technique (G1) and 21 using ICG-FC (G2). There were 27 girls and 16 boys, with median age at surgery of 11.5 years (range 7-17) and median weight of 47 kg (range 31-110). No conversions were reported in our series. In all ICG cases (except one patient under therapy with phenobarbital) the biliary tree was perfectly visualized during dissection. Intra-operative complications occurred in 3 G1 patients (13.6%): 2 bleedings from the Calot's triangle and 1 bleeding from the liver bed during the gallbladder removal. LC was significantly faster in G2 than in G1 (p = 0.001). In fact, the parameters analyzed (T1, T2, T3) were all significantly greater in G1 than in G2 (p = 0.001).

CONCLUSIONS

Based upon our experience, we strongly recommend the use of ICG-FC in all pediatric patients undergoing LC. ICG-guided fluorescence provided an excellent real-time visualization of the extrahepatic biliary tree and allowed faster and safer dissection, minimizing the risk of bile duct injuries. Furthermore, ICG use was clinically safe, with no adverse reactions to the product.