Near-infrared Fluorescence Imaging System Research Articles

Near-infrared fluorescent molecular probes with cetuximab in the in vivo fluorescence imaging for epithelial ovarian cancer.

Near-infrared fluorescence (NIRF) imaging is an excellent choice for image-guided surgery due to its simple operation and non-invasiveness. Developing tumor-specific fluorescent molecular probes is key to fluorescence imaging-guided surgery. EGFR (epidermal growth factor receptor) is closely related to the proliferation and growth of tumor cells and is highly expressed in epithelial ovarian cancer (EOC). The study aims to construct a NIR fluorescent molecular probe using cetuximab (an EGFR monoclonal antibody) and investigate its feasibility for targeting EOC in vivo through fluorescence imaging. We determined the expression of EGFR in EOC. NIR fluorescent molecular probe with cetuximab (cetuximab-Cy7) was chemically engineered and identified. The subcutaneous xenografted tumor model of EOC was induced using SKOV3-Luc cell line with positive expression of EGFR. Cetuximab-Cy7 was used for in vivo fluorescence imaging, and phosphate-buffered saline, free Cy7 dye and mouse isotype immunoglobulin G-Cy7 were used as controls. NIRF imaging system was performed to study the distribution and targeting of the probes. Tumors were imaged in situ and ex vivo, and fluorescent intensity was quantified. Resected specimens were analyzed to confirm diagnosis, and immunohistochemical (IHC) staining was used to identify EGFR expression. EGFR expression was increased in EOC tissues than fallopian tube tissues. The high expression of EGFR was significantly correlated with well-differentiation, residual lesions ≤ 1cm, no recurrence and increased survival. NIRF imaging showed that the cetuximab-Cy7 enabled detection of tumor lesions in EOC-bearing mice with the optimal dose of 30µg. The suitable imaging time window may be 24-96h post-injection. Ex vivo fluorescence imaging indicated that fluorescent signal was mainly detected in the tumor and the lung. IHC results confirmed that xenografts were EGFR positive. Cetuximab-Cy7 can specifically target the tumors of EOC xenografted nude mice. This research lays the foundation for future studies on EOC surgery navigation.

Platelet membrane coated r-SAK to improve thrombolytic efficacy by targeting thrombus

Abstract Background Thrombolytic therapy is one of the most effective treatments to achieve rapid thrombus clearance and recanalization of blocked vessels in thrombotic diseases. However, the application of thrombolytic strategy has been limited due to unsatisfied thrombolytic efficacy, relatively higher bleeding complications, and consequently restricted indications.[1] With the development of nanotechnology and biotechnology, platelet membrane nanoparticles have been developed to enable the targeted delivery of thrombolytic agents to local thrombus sites.[2] Recombinant staphylokinase (r-SAK) is a third-generation thrombolytic agent produced by genetic engineering technology. In this study, platelet membrane coated r-SAK (PLT-r-SAK) was constructed, and its thrombolytic efficacy was evaluated in in-vitro and in-vivo experiments. Purpose We aimed to construct a thrombus-targeting agent of PLT-r-SAK and investigate its thrombolytic efficacy. Methods PLT-r-SAK was prepared by encapsulating r-SAK into platelet membrane vesicles using a membrane extrusion method. An in-vitro thrombolytic experiment was performed to examine the thrombolytic efficacy of PLT-r-SAK, and a totally occluded femoral artery thrombosis model of rabbit was developed to evaluate the in-vivo thrombolytic efficacy of PLT-r-SAK. The changes in femoral artery pressure were adopted to assess the vessel opening status. Besides, the effect of the antiplatelet drugs on the thrombolytic efficacy of PLT-r-SAK was explored. Finally, near-infrared fluorescence imaging system was used to verify the thrombus-targeting effect of PLT-r-SAK. Results PLT-r-SAK was firstly constructed, which exhibited a uniformly dispersed spherical morphology with a diameter of 185.8 ± 1.5 nm and a zeta potential of -26.1 ± 0.8 mV. In the in-vitro animal experiment, the thrombolysis rate of PLT-r-SAK was significantly higher than that of the same (low) dose and 4-fold (high) dose r-SAK (Figure 1a, 1b). In the in-vivo experiment, the initial recanalization time of PLT-r-SAK was significantly shorter than that of the low dose and high dose r-SAK, and the duration of the reperfusion time of PLT-r-SAK was prolonged compared to low dose and high dose r-SAK (Figure 1c). Another in-vitro experiment showed that the increased thrombolysis rate of PLT-r-SAK could be inhibited by platelet poor plasma (PPP) from aspirin- and ticagrelor-treated patients. Finally, both the in-vitro and in-vivo near-infrared fluorescence imaging showed significantly higher radiant efficiency in the PLT-r-SAK group as compared to the NS group (Figure 2). Conclusions Platelet membrane coating significantly improves the thrombolytic efficacy of r-SAK, which is related to the thrombus-targeting activity of the platelet membrane and can be inhibited by aspirin- and ticagrelor-treated plasma.Thrombolytic efficacy of PLT-r-SAKThrombus-targeting evidence of PLT-r-SAK

Robot-assisted Surgery for Gastrointestinal Cancer Using Indocyanine Green Conjugated Endoscopic Marking Clip Under Firefly Fluorescence Imaging.

Intraoperative identification of the cancer location is often difficult during robot-assisted surgery, especially in early stage cancers. This study aimed to investigate the feasibility and accuracy of a novel endoscopic clip emitting near-infrared (NIR) fluorescence during robot-assisted surgery for gastrointestinal cancer. Preoperative placement of endoscopic marking clips equipped with NIR fluorescent resin was performed to determine the resection margins in six patients with gastrointestinal cancer. During robot-assisted surgery, a NIR fluorescence imaging system was used to detect the fluorescence. The evaluation examined whether fluorescence from the clips was visualized during robot-assisted surgery. The NIR fluorescent signals emitted from the clips were successfully detected in all six patients from the serosal surfaces, resulting in the quick and accurate identification of the resection line. There were no significant differences in age, sex, or body mass index between the patients in whom we could detect NIR fluorescence. This novel NIR fluorescent clip is a promising diagnostic tool for accurately detecting tumor locations during robot-assisted surgery for gastrointestinal cancer.

Validation of a semi-quantitative scoring system and workflow for analysis of fluorescence quantification in companion animals.

Many commercially available near-infrared (NIR) fluorescence imaging systems lack algorithms for real-time quantifiable fluorescence data. Creation of a workflow for clinical assessment and post hoc analysis may provide clinical researchers with a method for intraoperative fluorescence quantification to improve objective outcome measures. Scoring systems and verified image analysis are employed to determine the amount and intensity of fluorescence within surgical specimens both intra and postoperatively. Lymph nodes from canine cancer patients were obtained during lymph node extirpation following peritumoral injection of indocyanine green (ICG). First, a semi-quantitative assessment of surface fluorescence was evaluated. Images obtained with a NIR exoscope were analysed to determine fluorescence thresholds and measure fluorescence amount and intensity. Post hoc fluorescence quantification (threshold of Hue = 165-180, Intensity = 30-255) displayed strong agreement with semi-quantitative scoring (k = 0.9734, p < 0.0001). Fluorescence intensity with either threshold of 35-255 or 45-255 were significant predictors of fluorescence and had high sensitivity and specificity (p < 0.05). Fluorescence intensity and quantification had a strong association (p < 0.001). The validation of the semi-quantitative scoring system by image analysis provides a method for objective in situ observation of tissue fluorescence. The utilization of thresholding for ICG fluorescence intensity allows post hoc quantification of fluorescence when not built into the imaging system.

Near-infrared fluorescence imaging technology guided margin design in oral squamous cell carcinoma: a single-centre retrospective study.

The margin status of oral squamous cell carcinoma patients is considered to be predictive of recurrence and long-term survival. Therefore, precise intraoperative margin assessment is crucial. This study investigated the feasibility of using near-infrared fluorescence imaging technology to guide margin design in oral squamous cell carcinoma patients. In this retrospective study, indocyanine green solution was intravenously injected preoperatively into patients. Intraoperatively, the surgical area was illuminated using a near-infrared fluorescence imaging system, which caused the lesion to fluoresce in the surgical area. Surgery was performed with the assistance of fluorescence imaging. The fluorescence intensity of the lesion area and surrounding normal tissue was recorded during surgery. Intraoperative margins were sent for rapid pathology, and postoperative margin pathology results were documented. Sixteen patients were included in this study (7 males, 9 females), with an average age of 65.65 ± 12.37 years. Preoperative biopsy and postoperative pathology confirmed oral squamous cell carcinoma in all patients. No cancer cells were found in the margin pathology results. The average fluorescence intensity of the lesion area was 214 ± 4.70, and that of the surrounding normal tissue was 104.63 ± 3.14. There was no significant difference in the fluorescence intensity values of the lesion areas among all patients (F=0.38, P>0.05). There was a significant difference in fluorescence intensity between the lesion area and surrounding normal tissue (t=33.76, P<0.05). Near-infrared fluorescence imaging technology can aid in real-time imaging differentiation of lesion areas based on differences in fluorescence intensity during surgery. The use of this technology can assist surgeons in assessing the safety margin and reliably guide surgery.

A preliminary investigation of precise visualization, localization, and resection of pelvic lymph nodes in bladder cancer by using indocyanine green fluorescence-guided approach through intracutaneous dye injection into the lower limbs and perineum.

This study aimed to investigate the feasibility and effectiveness of using indocyanine green (ICG) injected intracutaneously through the lower limbs and perineum for visualized tracking, localization, and qualitative assessment of pelvic lymph nodes (LNs) in bladder cancer to achieve their accurate resection. First, ICG was injected into the LN metastasis model mice lower limbs, and real-time and dynamic in vivo and ex vivo imaging was conducted by using a near-infrared fluorescence imaging system. Additionally, 26 patients with bladder cancer were enrolled and divided into intracutaneous group and transurethral group. A near-infrared fluorescence imaging device with internal and external imaging probes was used to perform real-time tracking, localization, and resection of the pelvic LNs. The mice normal LNs and the metastatic LNs exhibited fluorescence. The metastatic LNs showed a significantly higher signal-to-background ratio than the normal LNs (3.9 ± 0.2 vs. 2.0 ± 0.1, p < 0.05). In the intracutaneous group, the accuracy rate of fluorescent-labeled LNs was 97.6%, with an average of 11.3 ± 2.4 LNs resected per patient. Six positive LNs were detected in three patients (18.8%). In the transurethral group, the accuracy rate of fluorescent-labeled LNs was 84.4%, with an average of 8.6 ± 2.3 LNs resected per patient. Two positive LNs were detected in one patient (12.5%). Following the intracutaneous injection of ICG into the lower limbs and perineum, the dye accumulates in pelvic LNs through lymphatic reflux. By using near-infrared fluorescence laparoscopic fusion imaging, physicians can perform real-time tracking, localization, and precise resection of pelvic LNs.

Efficacy of Neonatal Porcine Bone Marrow-Derived Mesenchymal Stem Cell Xenotransplantation for the Therapy of Hind Limb Lymphedema in Mice.

Lymphedema is an intractable disease with few effective therapeutic options. Autologous mesenchymal stem cell (MSC) transplantation is a promising therapy for this disease. However, its use is limited by the cost and time for preparation. Recently, xenotransplantation of porcine MSCs has emerged as an alternative to autologous MSC transplantation. In this study, we aimed to clarify the usefulness of neonatal porcine bone marrow-derived MSC (NpBM-MSC) xenotransplantation for the treatment of lymphedema. One million NpBM-MSCs were xenotransplanted into the hind limbs of mice with severe lymphedema (MSC transplantation group). The therapeutic effects were assessed by measuring the femoral circumference, the volume of the hind limb, the number and diameter of lymphatic vessels in the hind limb, and lymphatic flow using a near-infrared fluorescence (NIRF) imaging system. We compared the effects using mice with lymphedema that did not undergo NpBM-MSC transplantation (negative control group). The condition of the transplanted NpBM-MSCs was also evaluated histologically. The femoral circumference and volume of the hind limb had been normalized by postoperative day (POD) 14 in the MSC transplantation group, but not in the negative control group (P = 0.041). NIRF imaging revealed that lymphatic flow had recovered in the MSC transplantation group by POD 14, as shown by an increase in luminance in the hind limb. Histological assessment also showed that the xenotransplantation of NpBM-MSC increased the proliferation of lymphatic vessels, but they had been rejected by POD 14. The xenotransplantation of NpBM-MSCs is an effective treatment for lymphedema, and this is mediated through the promotion of lymphangiogenesis.

Monitoring Distribution of the Therapeutic Agent Dimethyl Sulfoxide via Solvatochromic Shift of Albumin-Bound Indocyanine Green.

We recently developed a novel hyperspectral excitation-resolved near-infrared fluorescence imaging system (HER-NIRF) based on a continuous-wave wavelength-swept laser. In this study, this technique is applied to measure the distribution of the therapeutic agent dimethyl sulfoxide (DMSO) by utilizing solvatochromic shift in the spectral profile of albumin-bound Indocyanine green (ICG). Using wide-field imaging in turbid media, complex dynamics of albumin-bound ICG are measured in mixtures of dimethyl sulfoxide (DMSO) and water. Phantom experiments are conducted to evaluate the performance of the HER-NIRF system. The results show that the distribution of DMSO can be visualized in the wide-field reflection geometry. One of the main purposes of the DMSO is to act as a carrier for other drugs, enhancing their effects by facilitating skin penetration. Understanding the solubility and permeability of drugs in vivo is very important in drug discovery and development. Hence, this HER-NIRF technique has great potential to advance the utilization of the therapeutic agent DMSO by mapping its distribution via the solvatochromic shift of ICG. By customizing the operational wavelength range, this system can be applied to any other fluorophores in the near-infrared region and utilized for a wide variety of drug delivery studies.

Cost-Effective Near Infrared Fluorescence Wide-Field Camera for Breast Tumor Imaging

Near-infrared (NIR) fluorescence imaging has long been proven useful for numerous medical applications, especially image-guided surgery since it can deeply penetrate tissue and acquire a fluorescence image from the FDA-approved fluorescence dye known as indocyanine green (ICG). NIR imaging-guided surgery can help enhance outcomes by better defining surgical margins and minimizing operative time. However, most commercial NIR fluorescence imaging systems are bulky and expensive. In this work, we introduce a low-cost and portable NIR fluorescence imaging system. The proposed system exploits an inexpensive complementary metal-oxide-semiconductor (CMOS) based on Nyxel® technology, considerably improving quantum efficiency (QE) in the NIR range. Therefore, it can acquire a NIR fluorescence image with outstanding quality. Furthermore, we conjugated ICG with nanoworm particles (NWs-ICG) since nanoparticle-conjugated dye can increase accumulation in a tumor. We show impressive applications of our system for <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ex vivo</i> tissues and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in vivo</i> image-guided surgery using NWs-ICG as a contrast agent for breast tumors from transgenic mice.

Superior Epididymal Artery-Based Paraepididymal Adipofascial Flap: An Experimental Adipofascial Flap Model in the Rat.

Flap surgery is widely performed in reconstructive surgery. Experimental research is vital to improve flap viability. However, the number of flap models for animals is still limited. In this study, we define a new adipofascial flap in rats that can be used to investigate pedicled flap and/or adipofascial flap physiology. Eight Wistar male rats were used. Under deep anesthesia, paraepididymal adipofascial flaps were harvested. Flap perfusion was assessed using a near-infrared fluorescence imaging system. The length of the flap and the diameter of the flap pedicle were measured. All animals (n = 8) had sufficient sizes of paraepididymal fat pad, and no animals were lost. The only postoperative complication was testicular hematoma, which was observed in 2 animals. The maximum length of the harvested paraepididymal adipofascial flap was 9.7 cm with a mean of 6.6 cm. The maximum width of the flap was 3.3 cm with a mean of 2.6 cm. The mean pedicle diameter of the paraepididymal adipofascial flap was 1.1 mm. Near-infrared fluorescence imaging revealed adequate perfusion in all flaps. The number of reported adipofascial flap models in animals is low, and they are mostly limited to flaps based on epigastric vessels. Superior epididymal artery-based paraepididymal adipofascial flap can be used as a pedicled flap model for studies focusing on adipofascial and/or pedicled flap physiology. Uncomplicated surgical technique and short operative time make this flap a valuable alternative to other flap models.

Targeted Imaging of Endometriosis and Image-Guided Resection of Lesions Using Gonadotropin-Releasing Hormone Analogue-Modified Indocyanine Green

Objective. In this study, we utilized gonadotropin-releasing hormone analogue-modified indocyanine green (GnRHa-ICG) to improve the accuracy of intraoperative recognition and resection of endometriotic lesions. Methods. Gonadotropin-releasing hormone receptor (GnRHR) expression was detected in endometriosis tissues and cell lines via immunohistochemistry and western blotting. The in vitro binding capacities of GnRHa, GnRHa-ICG, and ICG were determined using fluorescence microscopy and flow cytometry. In vivo imaging was performed in mouse models of endometriosis using a near-infrared fluorescence (NIRF) imaging system and fluorescence navigation system. The ex vivo binding capacity was determined using confocal fluorescence microscopy. Results. GnRHa-ICG exhibited a significantly stronger binding capacity to endometriotic cells and tissues than ICG. In mice with endometriosis, GnRHa-ICG specifically imaged endometriotic tissues (EMTs) after intraperitoneal administration, whereas ICG exhibited signals in the intestine. GnRHa-ICG showed the highest fluorescence signals in the EMTs at 2 h and a good signal-to-noise ratio at 48 h postadministration. Compared with traditional surgery under white light, targeted NIRF imaging-guided surgery completely resected endometriotic lesions with a sensitivity of 97.3% and specificity of 77.8%. No obvious toxicity was observed in routine blood tests, serum biochemicals, or histopathology in mice. Conclusions. GnRHa-ICG specifically recognized and localized endometriotic lesions and guided complete resection of lesions with high accuracy.

Single Camera-Based Dual-Channel Near-Infrared Fluorescence Imaging system.

In this study, we propose a single camera-based dual-channel near-infrared (NIR) fluorescence imaging system that produces color and dual-channel NIR fluorescence images in real time. To simultaneously acquire color and dual-channel NIR fluorescence images of two fluorescent agents, three cameras and additional optical parts are generally used. As a result, the volume of the image acquisition unit increases, interfering with movements during surgical procedures and increasing production costs. In the system herein proposed, instead of using three cameras, we set a single camera equipped with two image sensors that can simultaneously acquire color and single-channel NIR fluorescence images, thus reducing the volume of the image acquisition unit. The single-channel NIR fluorescence images were time-divided into two channels by synchronizing the camera and two excitation lasers, and the noise caused by the crosstalk effect between the two fluorescent agents was removed through image processing. To evaluate the performance of the system, experiments were conducted for the two fluorescent agents to measure the sensitivity, crosstalk effect, and signal-to-background ratio. The compactness of the resulting image acquisition unit alleviates the inconvenient movement obstruction of previous devices during clinical and animal surgery and reduces the complexity and costs of the manufacturing process, which may facilitate the dissemination of this type of system.

Application of near-infrared fluorescence imaging in the accurate assessment of surgical margins during breast-conserving surgery

ObjectiveTo evaluate the feasibility and accuracy of near-infrared fluorescence imaging technology for assessing margins during breast-conserving surgery for breast cancer.MethodsForty-three breast cancer patients who received surgical treatment at Yijishan Hospital of Wannan Medical College were selected. Before the operation, the patients were administered with an indocyanine green injection of 0.5 mg/kg intravenously 2 h before operation. During and after the operation, all patients underwent surgical margin monitoring with the near-infrared fluorescence imaging system for fluorescence imaging and acquisition of images and quantitative fluorescence intensity. During the operation, the patients’ tissue specimens were collected on the upper, lower, inner, outer, apical, and basal sides of the fluorescence boundary of the isolated lesions for pathological examination.ResultsFluorescence was detected in the primary tumor in all patients. The average fluorescence intensities of tumor tissue, peritumoral tissue, and normal tissue were 219.41 ± 32.81, 143.35 ± 17.37, and 105.77 ± 17.79 arbitrary units, respectively (P < 0.05, t test). The signal-to-background ratio of tumor to peritumor tissue and normal tissue was 1.54 ± 0.20 and 2.14 ± 0.60, respectively (P < 0.05, t test). Abnormal indocyanine green fluorescence was detected in 11.6% patients (5/43), including 3 patients with residual infiltrating carcinoma and 2 patients with adenosis with ductal dilatation.ConclusionThis study confirms the high sensitivity and specificity of near-infrared fluorescence imaging technology for breast-conserving surgery margin assessment. Near-infrared fluorescence imaging technology can be used as an intraoperative diagnosis and treatment tool to accurately determine the surgical margin and is of important guiding value in breast-conserving surgery for breast cancer.

Application of near-infrared fluorescence imaging in lingual lymph node screening and drainage pattern observation for tongue cancer.

Objective: Lingual lymph node (LLN) metastasis is regarded as an indicator of unfavorable prognosis and a crucial sign of the high degree of primary tumor aggressiveness. However, detecting LLN metastasis is an important but frequently overlooked aspect of diagnosis and surgical treatment planning. The study aims to identify LLNs by intraoperative near-infrared (NIR) fluorescence imaging with indocyanine green absorbed into human serum albumin (ICG: HSA) and describe the presence of lymphatic drainage channels from the floor of the mouth in patients with tongue carcinoma. Materials and Methods: 21 patients diagnosed with cT1-T4 squamous cell carcinoma (SCC) of the tongue margin and scheduled to undergo tumor resection and unilateral neck dissection were enrolled. After exposing the neck, the patients were injected with 0.3 ml of ICG: HSA (500 μM) in three quadrants around the tumor, excluding the mucous membrane of the basal region cavity. Employing a near-infrared fluorescence imaging system, the fluorescence of levels I, II, III, and IV was measured during neck dissection. Results: LLNs were detected in four patients and were identified as metastatic LLNs in all 21 patients. The near-infrared fluorescence imaging system showed the existence of lymphatic drainage channels in the floor of the mouth. In patients receiving peritumoral injection of ICG: HSA, the mean fluorescence intensity (MFI)of metastatic lymph nodes (LNs) (178.4 ± 64.39, mean ± SD) was higher than that in non-metastatic LNs (132.0 ± 76.5, mean ± SD) (p < 0.05). Conclusion: NIR fluorescence imaging with ICG: HSA could be used for intraoperative identification of LLNs and assist in the determination of metastatic lymph nodes for tongue carcinoma patients. Additionally, this finding demonstrates the feasibility of near-infrared fluorescence imaging in defining lymphatic drainage channels in the head and neck.

Preoperative indocyanine green fluorescence injection to accurately determine a proximal margin during robotic distal gastrectomy.

Adequate surgical margins following gastrectomy for gastric cancer are required. In addition, a method for accurately detecting tumor location without palpation is needed during robotic surgery. Although several methods have been reported, most of these either lack accuracy or require increased time and effort during intraoperative detection. Herein, we introduce a new method for detecting tumor location using preoperative indocyanine green (ICG) marking and the built-in ICG detection system of the da Vinci Xi Surgical System in robotic gastrectomy to determine appropriate surgical margins. We used this method to determine the resection line in six patients who underwent robotic distal gastrectomy for clinical T1 gastric cancer. One to three days before surgery, ICG was diluted to 1.0mg/mL, and 0.1mL of this diluted ICG solution was endoscopically injected at one site into the submucosal layer of the stomach, 1cm proximal to the tumor edge. Gastrectomy was performed using the da Vinci Xi surgical platform, equipped with a near-infrared fluorescence imaging system (Firefly®). The diameter of the fluorescent signal during gastrectomy was estimated to be approximately 2cm. The resection line was determined on the outer edge of the fluorescent signal, which ensured a tumor-free margin of ≥2cm. Fluorescent signals were successfully observed in all cases. Moreover, the required 2-cm surgical margin was achieved in all cases. We could successfully determine proximal margins using preoperative ICG injection marking during robotic distal gastrectomy for gastric cancer.

Fluorescence Imaging-Guided Identification of Thymic Masses Using Low-Dose Indocyanine Green.

Indocyanine green (ICG) fluorescence imaging has been used to detect many types of tumors during surgery; however, there are few studies on thymic masses and the dose and time of ICG injection have not been optimized. We aimed to evaluate the optimal ICG injection dose and timing for detecting thymic masses during surgery. Forty-nine consecutive patients diagnosed with thymic masses on preoperative computed tomography (CT) and scheduled to undergo thymic cystectomy or thymectomy were included. Patients were administered 1, 2, or 5mg/kg of ICG at different times. Thymic masses were observed during and after surgery using a near-infrared fluorescence imaging system, and the fluorescence signal tumor-to-normal ratio (TNR) was analyzed. Among the 49 patients, 14 patients with thymic cysts showed negative fluorescence signals, 33 patients with thymoma or thymic carcinoma showed positive fluorescence signals, and 2 patients showed insufficient fluorescence signals. The diagnosis of thymic masses based on CT was correct in 32 (65%) of 49 cases; however, the differential diagnosis of thymic masses based on NIR signals was correct in 47 of 49 cases (96%), including 14 cases of thymic cysts (100%) and 33 cases of thymomas or thymic carcinomas (94%). In addition, TNR was not affected by the time or dose of ICG injection, histological type, stage, or tumor size. Low-dose intravenous injection of ICG at flexible time can detect thymic tumors. In addition, thymic cysts can be distinguished from thymomas or thymic carcinomas during surgery by the absence of ICG fluorescence signals.

Bi-modal near-infrared fluorescence and ultrasound imaging via a transparent ultrasound transducer for sentinel lymph node localization.

Sentinel lymph node biopsy with an indocyanine green-based near-infrared fluorescence imaging system avoids the shortcomings of using a radioisotope or a combination of a blue dye and a radioactive tracer. To improve surgical precision, recent research has provided a depth profile of the sentinel lymph node by fusing fluorescence and ultrasound imaging. Here, we present a combined near-infrared fluorescence and ultrasound imaging system based on a transparent ultrasound transducer. The transparent ultrasound transducer enables seamless coaxial alignment of the fluorescence and ultrasound beam paths, allowing bi-modal observation of a single region of interest. Further, we demonstrate that the sentinel lymph node of mice injected with indocyanine green can be successfully localized and dissected based on information from the bi-modal imaging system.

A study on setting standards for near-infrared fluorescence-image guided surgery (NIRFGS) time lapse monitoring based on preoperative liver function assessment.

BackgroundThis study aimed to explore the relationship between the fluorescence intensity of indocyanine green (ICG) in near-infrared fluorescence guided surgery (NIRFGS) and preoperative liver function indicators.MethodsA total of 12 4T1 tumor-bearing mice were used for model establishment. Intraperitoneal injection (i.p.) of 20% carbon tetrachloride (CCl4) corn oil solution (50 µL) was given to mice in the liver injury model group, 24 hours after injection, the model was established, while the control group received 0% CCl4 corn oil solution (50 µL) (n=6 for each group). Additionally, doses of 8 mg/kg and 1 mg/kg of free ICG were injected intravenously (i.v.) (n=3 in each group). Fluorescence was imaged in vivo using an NIR fluorescence imaging system at different time points (1, 2, 4, 8, 12, 24, 48, and 72 h) after injection.ResultsThe absolute fluorescence intensity of mice in the liver injury model group was stronger than that in the control group. Mice in the liver injury model group had the same clearance rate of ICG from the tumor as normal mice. However, the background clearance rate was slower than that of normal mice, which prolonged the optimal tumor to background ratio (TBR) time. Correlation analysis was also used to determine which preoperative liver function parameters were most correlated with hepatic ICG clearance.ConclusionsLiver injury does not significantly affect the maximum TBR, but prolongs the optimal TBR time, and at the same time, a wider and more stable surgical window will appear. This study showed that a prolonged surgical start time is feasible according to preoperative liver function testing using NIR fluorescence imaging technology.

Host–guest interactions of indocyanine green with β-cyclodextrin permit real-time characterization of the rat lymphatic system

ObjectiveFluorescence contrast technology using indocyanine green (ICG) could be useful for the rapid, dynamic, and objective assessment of blood vessels and the surrounding tissues when combined with near-infrared (NIR) imaging. Although ICG is a clinically available NIR fluorescence imaging probe, it can easily aggregate and is, thus, unstable. In the present study, we examined the efficacy of a host–guest ICG–β-cyclodextrin (CD) complex, which is used in pharmaceutics to improve the water solubility, stability, and bioavailability of hydrophobic molecules, for NIR imaging after hind footpad administration in a rat model. MethodsTo verify the performance of the ICG-β-CD complex with the host–guest self-assembly method in vivo, we performed simultaneous small animal (IVIS Spectrum system; PerkinElmer, Waltham, MA) and clinical (DIGI-MIH-001 near-infrared fluorescence imaging system; Beijing Digital Precision Medical Technology Co, Ltd, Beijing, China) imaging and evaluated the fluorescent properties of the ICG-β-CD complex in the hind footpad model of Sprague-Dawley male rats. ResultsWe successfully prepared the ICG-β-CD complex. Compared with ICG, in vivo experiments showed that this complex had reduced absorbance at 710 nm and increased absorbance at 780 nm, indicating that it could prevent the dimeric aggregation of ICG, and a significantly higher fluorescence intensity at 730 nm excitation. After injection of 1.25 mg/mL of ICG or ICG-β-CD complex solutions into the rat hind footpad, fluorescent NIR lymphatic images were observed with both imaging systems. During the 12-hour observation period, the signal background ratio of ICG-β-CD showed a greater acute increase and a higher signal background ratio compared with ICG. The signal background ratio of ICG-β-CD was 125 to 100 from 260 to 540 minutes. These in vivo data suggest that ICG-β-CD has greater diffusion from the injection site and faster transport to the lymphatic system compared with ICG. ConclusionsICG-β-CD showed faster lymphatic transport than ICG, allowing for more rapid lymphatic NIR imaging. Thus, the ICG-β-CD complex might be a promising fluorescent agent for clinical lymphatic NIR imaging.

Comparison of normal hindlimb lymphatic systems in rats with detours present after lymphatic flow blockage.

In the present study, we aimed to identify the normal hindlimb lymphatic systems in rats and compare them with the detours after lymphatic flow blockage. The lymphatic systems of the hindlimbs of normal rats were investigated via lymphography using a near-infrared fluorescence imaging system. The lymphatic vessels were stained using Evans Blue. The lymphatic flow was blocked through lymphatic vessel ligation combined with inguinal and popliteal lymph node dissection. Detours that appeared after 30 days were visualized using lymphography and immunostaining with anti-podoplanin antibodies. Three main results were obtained in the present study. First, the deep medial system, the superficial medial system, a connection between the superficial and deep medial lymphatic systems, and the superficial lateral system, were elucidated. Second, three types of detours, namely the detour of the lateral abdomen, the detour to the lymphatic vessel near the midline of the abdomen, and the detour to the contralateral inguinal lymph node, were identified after lymphatic flow blockage. Lastly, detours were located in the fatty layer above the panniculus carnosus muscle and their lumina were wide. The histology suggested that the detour was a pre-collecting lymphatic vessel. Lymphatic routes in the rat hindlimbs after lymphatic flow blockage were different from those of the normal rat lymphatic system. It was suggested that the detour is a pre-collecting lymphatic vessel and that encouraging its development may be a new method of simple lymphatic drainage.