[Analysis of indocyanine green plasma disappearance rate in clinical practice]. / Vybor metodiki opredeleniya skorosti plazmennoi eliminatsii indotsianina zelenogo v klinicheskoi praktike.

OBJECTIVE: To justify the optimal method for determining indocyanine green plasma disappearance rate (PDRICG). MATERIAL AND METHODS: We analyzed PDRICG in intensive care units. Indocyanine green was administered intravenously at a dose of 0.25 mg/kg. PDRICG was analyzed simultaneously by using of three methods: 1) PDD (PiCCO2 LiMON device), 2) SBS with analysis of plasma samples on precise spectrophotometer, 3) SBS with analysis of plasma samples on simple experimental photometer. RESULTS: PDD method was used for 346 PDRICG tests in 256 patients. Of these, 14.3% of measurements were erroneous. Paired tests using PDD and SBS methods were performed in 299 cases. SBS method resulted erroneous data in 0.6% of cases. Certain correlation (r=0.79, p<0.001) was found between the reference method (SBS with spectrophotometry) and the PDD method. Bland-Altman plot for these two methods showed that proportional bias of mean difference was caused by extremely high PDRICG of the PDD method (for example, more than 30%/min). Comparison of two SBS variants (spectrophotometer and experimental photometer) revealed good correlation (r=0.91, p<0.001). CONCLUSION: SBS method for measuring PDRICG ensures accurate results under mechanical interferences in patients with impaired capillary blood flow. This eliminates the need for redo measurement. Duplication of the PDD and SBS methods is recommended when repeating the test is not possible (organ donors).

Shortwave-Infrared Fluorescent Molecular Imaging Probes Based on π-Conjugation Extended Indocyanine Green.

Recently, shortwave-infrared (SWIR) fluorescence imaging for the optical diagnostics of diseases has attracted much attention as a new noninvasive imaging modality. For this application, the development of SWIR molecular imaging probes with high biocompatibility is crucial. Although many types of biocompatible SWIR fluorescent probes based on organic dyes have been reported, there are no SWIR-emitting molecular imaging probes that can be used for the detection of specific biomolecules in vivo. To apply SWIR-emitting molecular imaging probes to biomedical fields, we developed a biocompatible SWIR fluorescent dye based on π-conjugation extended indocyanine green (ICG), where ICG is the only approved near-infrared dye by the US Food and Drug Administration (FDA) for use in the clinic. Using the π-conjugation extended ICG, we prepared SWIR molecular imaging probes that can be used for in vivo tumor imaging. Herein, we demonstrate noninvasive SWIR fluorescence imaging of human epidermal growth factor receptor 2 (HER2)-positive and epidermal growth factor receptor (EGFR)-positive breast tumors using π-conjugation extended ICG and monoclonal antibody conjugates. The presented π-conjugation extended ICG analog probes will be a breakthrough to apply SWIR fluorescence imaging in biomedical fields.

Hemodynamic and anti-inflammatory effects of early esmolol use in hyperkinetic septic shock: a pilot study.

BACKGROUND: Several studies have shown that heart rate control with selective beta-1 blockers in septic shock is safe. In these trials, esmolol was administered 24 h after onset of septic shock in patients who remained tachycardic. While an earlier use of beta-blockers might be beneficial, such use remains challenging due to the difficulty in distinguishing between compensatory and non-compensatory tachycardia. Therefore, the Esmosepsis study was designed to study the effects of esmolol aimed at reducing the heart rate by 20% after the initial resuscitation process in hyperkinetic septic shock patients on (1) cardiac index and (2) systemic and regional hemodynamics as well as inflammatory patterns. METHODS: Nine consecutive stabilized tachycardic hyperkinetic septic shock patients treated with norepinephrine for a minimum of 6 h were included. Esmolol was infused during 6 h in order to decrease the heart rate by 20%. The following data were recorded at hours H0 (before esmolol administration), H1-H6 (esmolol administration) and 1 h after esmolol cessation (H7): systolic arterial pressure, diastolic arterial pressure, mean arterial pressure, central venous pressure, heart rate, PICCO transpulmonary thermodilution, sublingual and musculo-cutaneous microcirculation, indocyanine green clearance and echocardiographic parameters, diuresis, lactate, and arterial and venous blood gases. RESULTS: Esmolol was infused 9 (6.4-11.6) hours after norepinephrine introduction. Esmolol was ceased early in 3 out of 9 patients due to a marked increase in norepinephrine requirement associated with a picture of persistent cardiac failure at the lowest esmolol dose. For the global group, during esmolol infusion, norepinephrine infusion increased from 0.49 (0.34-0.83) to 0.78 (0.3-1.11) µg/min/kg. The use of esmolol was associated with a significant decrease in heart rate from 115 (110-125) to 100 (92-103) beats/min and a decrease in cardiac index from 4.2 (3.1-4.4) to 2.9 (2.5-3.7) l/min/m-2. Indexed stroke volume remained unchanged. Cardiac function index and global ejection fraction also markedly decreased. Using echocardiography, systolic, diastolic as well as left and right ventricular function parameters worsened. After esmolol cessation, all parameters returned to baseline values. Lactate and microcirculatory parameters did not change while the majority of pro-inflammatory proteins decreased in all patients. CONCLUSION: In the very early phase of septic shock, heart rate reduction using fast esmolol titration is associated with an increased risk of hypotension and decreased cardiac index despite maintained adequate tissue perfusion (NCT02068287).

Absolute Purity Determination of a Hygroscopic Substance, Indocyanine Green, Using Quantitative NMR (qNMR).

Quantitative NMR (qNMR) is applied to determine the absolute quantitative value of analytical standards for HPLC-based quantification. We have previously reported the optimal and reproducible sample preparation method for qNMR of hygroscopic reagents, such as saikosaponin a, which is used as an analytical standard in the assay of crude drug section of Japanese Pharmacopoeia (JP). In this study, we examined the absolute purity determination of a hygroscopic substance, indocyanine green (ICG), listed in the Japanese Pharmaceutical Codex 2002, using qNMR for standardization by focusing on the adaptation of ICG to JP. The purity of ICG, as an official non-Pharmacopoeial reference standard (non-PRS), had high variation (86.12 ± 2.70%) when preparing qNMR samples under non-controlled humidity (a conventional method). Additionally, residual ethanol (0.26 ± 0.11%) was observed in the non-PRS ICG. Next, the purity of non-PRS ICG was determined via qNMR when preparing samples under controlled humidity using a saturated sodium bromide solution. The purity was 84.19 ± 0.47% with a lower variation than that under non-controlled humidity. Moreover, ethanol signal almost disappeared. We estimated that residual ethanol in non-PRS ICG was replaced with water under controlled humidity. Subsequently, qNMR analysis was performed when preparing samples under controlled humidity in a constant temperature and humidity box. It showed excellent results with the lowest variation (82.26 ± 0.19%). As the use of a constant temperature and humidity box resulted in the lowest variability, it is recommended to use the control box if the reference ICG standard is needed for JP assays.

Liver function assessment using indocyanine green plasma disappearance rate in a young male with icteric leptospirosis: a case report.

BACKGROUND: Leptospirosis is one of the leading global zoonotic causes of morbidity and mortality. It is induced by a pathogenic spirochete of the genus Leptospira. The icteric form of leptospirosis is characterized by pronounced hyperbilirubinemia and associated with significantly increased mortality. Conventional static liver function tests insufficiently assess hepatic damage and have limited prognostic value. Dynamic tests, such as indocyanine green plasma (ICG) clearance, more adequately reflect hepatic functional status. In this case report we describe the ICG plasma disappearance rates (ICG-PDR) in a patient with leptospirosis and massive hyperbilirubinemia, expanding our knowledge of liver dysfunction in icteric leptospirosis. CASE PRESENTATION: A 21-year-old Caucasian man presented with acute-onset jaundice, myalgia, fever and headaches. Laboratory tests upon admission revealed, most notably, acute kidney failure and hyperbilirubinemia of 17 mg/dl with mild elevation of aminotransferases. In the course of the following 4 days, total serum bilirubin increased to 54 mg/dl. The clinical outcome was favorable with intravenous ceftriaxone and doxycycline. Presumptive diagnosis of leptospirosis was later confirmed by PCR-based amplification of leptospiral DNA in the blood. ICG-PDR values, bilirubin as well as aminotransferases were recorded throughout hospitalization and a 3-month follow-up period. Initially dramatically reduced ICG-PDR (2.0%/min, normal range: 18-25%/min) rapidly normalized within 10 days, while bilirubin remained elevated up to week 7. Mild elevation of serum alanine aminotransferase was at its peak of 124 U/l by day 12 and reached close to normal levels by week 7 upon admission. CONCLUSIONS: Markedly diminished ICG-PDR values presented in this case report suggest severe liver function impairment in the acute phase of icteric leptospirosis. Prolonged elevation of serum bilirubin may not adequately reflect recovery of liver injury in this disease. ICG clearance appears to be a promising marker for the detection of hepatic dysfunction and recovery in icteric leptospirosis in addition to the static tests.

A study on uterine lymphatic anatomy for standardization of pelvic sentinel lymph node detection in endometrial cancer.

OBJECTIVE: To describe the anatomy of uterine lymphatic drainage following cervical or fundal tracer injection to enable standardization of a pelvic sentinel lymph node (SLN) concept in endometrial cancer (EC). METHODS: A prospective consecutive study of women with EC was conducted. A fluorescent dye (Indocyanine green) was injected into the cervix (n=60) or the uterine fundus (n=30). A systematic trans- and retroperitoneal mapping of uterine lymphatic drainage was performed. Positions of the pelvic SLNs, defined by afferent lymph vessels, and lymph node metastases were compared. RESULTS: Two consistent lymphatic pathways with pelvic SLNs were identified irrespective of injection site; an upper paracervical pathway (UPP) with draining medial external and/or obturator lymph nodes and a lower paracervical pathway (LPP) with draining internal iliac and/or presacral lymph nodes. Bilateral display of at least one pelvic pathway following cervical and fundal injection occurred in 98% and 80% respectively (p=0.005). Bilateral display of both pelvic pathways occurred in 30% and 20% respectively (p=0.6) as the LPP was less often displayed. Nearly one third of the 19% node positive patients had metastases along the LPP. No false negative SLNs were identified. CONCLUSIONS: Based on uterine lymphatic anatomy a bilateral detection of at least one SLN in both the UPP and LPP should be aimed for. Absence of display of the LPP may warrant a full presacral lymphadenectomy. Although pelvic pathways and positions of SLNs are independent of the tracer injection site, cervical injection is preferable due to a higher technical success rate.

Value of Preoperative Indocyanine Green Clearance Test for Predicting Post-Hepatectomy Liver Failure in Noncirrhotic Patients.

BACKGROUND Liver failure is the most feared complication following hepatectomy. Post-hepatectomy liver failure (PHLF) is closely related to the remnant liver volume, and functional reserve. There are several methods for predicting PHLF prior to liver resection. The indocyanine green (ICG) clearance test was popularized in patients with hepatocellular cancer (HCC). We aim to demonstrate the value of preoperative ICG clearance measurement via pulse spectrophotometer (LIMON®) in prediction of PHLF in noncirrhotic patients prior to liver resection. MATERIAL AND METHODS Fifty-three noncirrhotic patients who underwent liver resection due to different pathologies were included. Retrospectively collected clinical data, including the preoperative ICG clearance measurements and remnant liver volumes of the patients, were statistically evaluated according to the PHLF criteria of the International Study Group of Liver Surgery. RESULTS Four (7.5%) patients with PHLF were observed. There was no significant difference between PHLF and non-PHLF groups regarding ICG clearance measurements with cut-off values of 5% and 9.5%. CONCLUSIONS The ICG clearance test does not satisfy our expectations in noncirrhotic patients in predicting PHLF. We believe that the ICG clearance test should be reserved for patients with cirrhosis and/or HCC. This test could be an option for noncirrhotic patients with chronic active hepatitis, advanced-grade fatty livers, or for patients who received long-term preoperative chemotherapy, and also for patients who underwent single or multiple sessions of TACE or TARE prior to liver resection. If the routine selection criteria have been fulfilled, there is no further need to perform the ICG clearance test for living liver donors.

Affinity of Indocyanine Green in the Detection of Colorectal Peritoneal Carcinomatosis.

Indocyanine green (ICG) is increasingly being used in digestive oncology. In colorectal cancer, ICG can be used to detect lymph node metastasis and hepatic metastasis on the surface of the liver. In peritoneal carcinomatosis, it was previously suspected that the diffusion of ICG in the tumor mass was due to the enhanced permeability and retention effect; however, this phenomenon has not been clearly demonstrated. Using bevacizumab, an antibody directed against vascular endothelial growth factor that consequently inhibits neoangiogenesis, we sought to confirm the mode of ICG diffusion. We compared the fluorescence of peritoneal carcinomatosis nodules from patients who had previously received bevacizumab during their oncologic treatment with those who did not receive this therapy. The sensitivity of the carcinomatosis nodule fluorescence was higher in the patients who did not receive bevacizumab compared with those who received the drug (76.3% and 65.0%, respectively). The rate of false-negative results was higher in the bevacizumab group than in the group that did not receive the drug (53.8% and 42.9%, respectively). Using bevacizumab, we demonstrate that the enhanced permeability and retention effect causes ICG accumulation in peritoneal carcinomatosis resulting from colorectal cancer.

The Application of Heptamethine Cyanine Dye DZ-1 and Indocyanine Green for Imaging and Targeting in Xenograft Models of Hepatocellular Carcinoma.

Near infrared fluorescence (NIRF) imaging has strong potential for widespread use in noninvasive tumor imaging. Indocyanine green (ICG) is the only Food and Drug Administration (FDA) -approved NIRF dye for clinical diagnosis; however, it is unstable and poorly targets tumors. DZ-1 is a novel heptamethine cyanine NIRF dye, suitable for imaging and tumor targeting. Here, we compared the fluorescence intensity and metabolism of DZ-1 and ICG. Additionally, we assayed their specificities and abilities to target tumor cells, using cultured hepatocellular carcinoma (HCC) cell lines, a nude mouse subcutaneous xenograft model of liver cancer, and a rabbit orthotopic transplantation model. We found that DZ-1 accumulates in tumor tissue and specifically recognizes HCC in subcutaneous and orthotopic models. The NIRF intensity of DZ-1 was one order of magnitude stronger than that of ICG, and DZ-1 showed excellent intraoperative tumor targeting in the rabbit model. Importantly, ICG accumulated at tumor sites, as well as in the liver and kidney. Furthermore, DZ-1 analog-gemcitabine conjugate (NIRG) exhibited similar tumor-specific targeting and imaging properties, including inhibition of tumor growth, in HCC patient-derived xenograft (PDX) mice. DZ-1 and NIRG demonstrated superior tumor-targeting specificity, compared to ICG. We show that DZ-1 is an effective molecular probe for specific imaging, targeting, and therapy in HCC.

In vitro and in vivo analysis of indocyanine green-labeled panitumumab for optical imaging-a cautionary tale.

Indocyanine green (IC-Green), the only FDA approved near-infrared (NIR) fluorophore for clinical use, is attractive to researchers for the development of targeted optical imaging agents by modification of its structure and conjugation to monoclonal antibodies (mAbs) or their fragments. IC-Green derivative, ICG-sulfo-OSu (ICG-sOSu), is frequently used for antibody conjugation. However, ICG-sOSu is amphiphilic and readily facilitates aggregation of mAbs that is not easily separable from the desired immunoconjugates. Complications originating from this behavior are frequently overlooked by researchers. This study examined detailed chemical and biological characteristics of an ICG-sOSu-labeled mAb, panitumumab, and provided a clinically applicable strategy to deliver a pure conjugation product. Size-exclusion high-performance liquid chromatography (SE-HPLC) analysis of conjugation reactions, performed at molar reaction ratios of ICG-sOSu: mAb of 5, 10, or 20, resulted in isolable desired ICG-sOSu-panitumumab conjugation product in 72%, 53%, and 19% yields, respectively, with the remainder consisting of high molecular weight aggregates (>150 kDa) 14%, 30%, and 51%, respectively. The HPLC-purified ICG-sOSu-panitumumab products were analyzed by native and SDS polyacrylamide gel electrophoresis (PAGE) followed by optical imaging. Results indicated that the interaction between ICG-sOSu and panitumumab was due to both covalent and noncovalent binding of the ICG-sOSu to the protein. Noncovalently bound dye in the ICG-sOSu-panitumumab conjugate products was removed by extraction with ethyl acetate to further purify the HPLC-isolated conjugation products. With conserved immunoreactivity, excellent target-specific uptake of the doubly purified bioconjugates was observed with minimal liver retention in athymic nude mice bearing HER1-expressing tumor xenografts. In summary, the preparation of well-defined bioconjugate products labeled with commercial ICG-sOSu dye is not a simple process and control of the conjugation reaction ratio and conditions is crucial. Furthermore, absolute purification and characterization of the products is necessitated prior to in vivo optical imaging. Use of validated and characterized dye conjugate products should facilitate the development of clinically viable and reproducible IC-Green derivative and other NIR dye mAb conjugates for optical imaging applications.

Real-time optoacoustic tomography of indocyanine green perfusion and oxygenation parameters in human finger vasculature.

We interrogated whether optoacoustic tomography could be employed to study blood functional parameters and biodistribution of injected fluorescent agents in humans. Using a multichannel scanner at a frame rate of 10 images per second, we obtained cross-sectional images of the human finger in real time, before and after the administration of indocyanine green. We demonstrated that multispectral optoacoustic tomography can sense fast flow kinetics and resolve spatiotemporal characteristics of a common fluorochrome in human vasculature at clinically relevant concentrations. We further register ICG images with oxygen saturation maps and anatomical views of the proximal interphalangeal joint of a healthy volunteer.

A novel endoscopic fluorescent clip visible with near-infrared imaging during laparoscopic surgery in a porcine model.

BACKGROUND: In gastrointestinal cancer surgery, particularly in early cancer, accurate tumor localization is important in order to determine the extent of resection. In laparoscopic surgery, because of the inability to palpate the lesion, the most prevalent method of localization is endoscopic tattooing. However, complicated maneuvering makes it difficult to control local dye spreading and dye leakage into the intraperitoneal cavity. A simpler, safe method is needed. In this study, we developed a novel method for applying fluorescence-coated endoscopic clips to visualize locations inside the colon during laparoscopic surgery. We tested the procedure in an in vivo porcine model and with ex vivo human colon tissues. METHODS: Bovine serum albumin was conjugated to indocyanine green or the succinimidyl ester CF™ 790 to form a pasty mixture, which was used to coat the front ends of endoscopic clips. The fluorescence-coated clips were endoscopically placed on the mucosal surface of a porcine colon. Using an Olympus near-infrared laparoscopy system, we attempted to identify the fluorescent clips from the outer, serosal side of the porcine colon during laparoscopic surgery in vivo. The clips were also evaluated using ex vivo human colon tissues. RESULTS: After placing two clips on the inner, mucosal surface of the porcine colon, we used near-infrared laparoscopy to view them from the outer, serosal surface of the colon in real time during in vivo laparoscopic surgery. We also identified the fluorescence-coated clips through human colon tissues in an ex vivo study. CONCLUSIONS: We developed a novel, fluorescence-coated clip that can be placed endoscopically for rapid, exact localization of colonic lesions. The clips were successfully visualized with near-infrared fluorescence imaging during laparoscopic surgery in an in vivo porcine model and in ex vivo human colon tissues.

Time-to-peak values can estimate hepatic functional reserve in patients undergoing surgical resection: a comparison between perfusion CT and indocyanine green retention test.

OBJECTIVE: To evaluate the potential usefulness of perfusion computed tomography (CT) for the estimation of hepatic functional reserve in patients scheduled for surgical resection and to compare the results with those of the indocyanine green retention test results. METHODS: Thirty-one patients with hepatobiliary malignancies were included. Perfusion CT and indocyanine green retention test were performed on the same day, and their results were compared using Pearson correlation test. RESULTS: A strong correlation was found between perfusion CT time-to-peak values and indocyanine green retention rate at 15 minutes and indocyanine green plasma disappearance rate values (R, 0.789 and -0.790; R, 0.832 and -0.823, respectively; P < 0.0001). CONCLUSIONS: Perfusion CT may be useful for the preoperative noninvasive estimation of hepatic functional reserve for patients undergoing liver resection.

Mini review of ultrafast fluorescence polarization spectroscopy [invited].

A mini review is presented on the theory, experiment, and application of the ultrafast fluorescence polarization dynamics and anisotropy with examples of two important medical dyes, namely Indocyanine Green and fluorescein. The time-resolved fluorescence polarization spectra of fluorescent dyes were measured with the excitation of a linearly polarized femtosecond laser pulse, and detected using a streak camera. The fluorescence emitted from the dyes is found to be partially oriented (polarized), and the degree of polarization of emission decreases with time. The decay of the fluorescence component polarized parallel to the excitation beam was found to be faster than that of the perpendicular one. Based on the physical model on the time-resolved polarized emission spectra in nanosecond range first described by Weber [J. Chem. Phys.52, 1654 (1970)], a set of first-order linear differential equations was used to model fluorescence polarization dynamics and anistropy of dye in picoseconds range. Using this model, two important decay parameters were identified separately: the decay rate of total emission intensity and the decay rate of the emission polarization affected by the rotation of fluorescent molecules causing the transfer of emission polarization from one orthogonal component to another. These two decay rates were separated and extracted from the measured time-resolved fluorescence polarization spectra. The emission polarization difference among dyes arising from different molecular volumes was used to enhance the image contrast.

Intraoperative ICG plasma disappearance rate helps to predict absence of early postoperative complications after orthotopic liver transplantation.

Early postoperative complications after orthotopic liver transplantation (OLT) are a common problem in intensive care medicine. Adequate assessment of initial graft function remains difficult, however, plasma disaperance rate of indocyanine green (PDRICG) may have an additional diagnostic and prognostic value in this setting. We retrospectively evaluated the ability of intraoperative PDRICG values to predict absence of early postoperative complications in 62 subjects. PDRICG was measured non-invasively by pulse dye densitometry during surgery and was correlated with initial graft function. At the end of surgery, PDRICG was higher in patients without complications: 24.9 % min(-1) (n = 40) versus 21.0 % min(-1), (n = 22; p = 0.034). An area under the ROC curve (AUROC) for PDRICG was 0.70, while the AUROC for pH, lactate and PT at ICU admission were 0.53, 0.50 and 0.46, respectively. The AUROC of serum bilirubin and PT at postoperative day 5 were 0.68 and 0.49, respectively. The optimal cut-off PDRICG value for predicting absence of development early postoperative complications was determined to be 23.5 % min(-1) with 72.4 % sensitivity and 71.0 % specificity. Intraoperative point-of-care PDRICG measurement during OLT already predicts absence of early postoperative complications, better and earlier than clinically used laboratory parameters.

Filamentous, mixed micelles of triblock copolymers enhance tumor localization of indocyanine green in a murine xenograft model.

Polymeric micelles formed by the self-assembly of amphiphilic block copolymers can be used to encapsulate hydrophobic drugs for tumor-delivery applications. Filamentous carriers with high aspect ratios offer potential advantages over spherical carriers, including prolonged circulation times. In this work, mixed micelles composed of poly(ethylene oxide)-poly[(R)-3-hydroxybutyrate]-poly(ethylene oxide) (PEO-PHB-PEO) and Pluronic F-127 (PF-127) were used to encapsulate a near-infrared fluorophore. The micelle formulations were assessed for tumor accumulation after tail vein injection to xenograft tumor-bearing mice by noninvasive optical imaging. The mixed micelle formulation that facilitated the highest tumor accumulation was shown by cryo-electron microscopy to be filamentous in structure compared to spherical structures of pure PF-127 micelles. In addition, increased dye loading efficiency and dye stability were attained in this mixed micelle formulation compared to pure PEO-PHB-PEO micelles. Therefore, the optimized PEO-PHB-PEO/PF-127 mixed micelle formulation offers advantages for cancer delivery over micelles formed from the individual copolymer components.

Photodynamic properties of vital dyes for vitreoretinal surgery.

The purpose of this study was to evaluate photodynamic properties of indocyanine green (ICG), brilliant blue G (BBG) and trypan blue (TB) as currently used vital dyes for chromovitrectomy. Under consideration of intraoperative illumination intensities and dye concentrations, a simulative in vitro investigation was set up. Therefore, standardized dilutions of original ICG, BBG and TB vials were irradiated at a wavelength of 366 nm with an intensity of 14 µW/cm2 between 0 and 48 h. After this, all samples were measured spectroscopically in a 220- to 750-nm bandwidth. Analyzing the vital dyes over the time course, an exponential photolysis was observed for ICG, whereas BBG and TB presented photostable properties. Regarding ICG, 5% of the concentration was degraded to toxic metabolites every 20 min. For this reason, our study provides evidence that intraocular dye concentrations and modern endoillumination systems alone cannot fully prevent ICG photodegradation.

The new method to make diagnosis and identify the location of leakage of pleuroperitoneal communication in peritoneal dialysis patients.

Pleuroperitoneal communication is a severe complication in peritoneal dialysis, and about half of the patients forced to discontinue peritoneal dialysis. The method of coloring dialysis solution by indocyanine green or CT peritoneography have been reported to make diagnosis of pleuroperitoneal communication, however sensitivity of these tests is not a satisfactory level. By repairing the pleural hole with thoracoscopic surgery, it is possible to resume peritoneal dialysis. However, the recurrence rate is very high unless precisely detecting the location of the pleural hole during surgery. We report three cases of pleuroperitoneal communication in peritoneal dialysis patients, in which we found the combination of contrast-enhanced ultrasonography and the indocyanine green fluorescence system are reliable method to make diagnosis and identify the location of leakage of pleuroperitoneal communication. By making definite diagnosis and precisely identifying the localization, we were able to close diaphragm holes by video-assisted thoracoscopic surgery.

In vivo multispectral photoacoustic and photothermal flow cytometry with multicolor dyes: a potential for real-time assessment of circulation, dye-cell interaction, and blood volume.

Recently, photoacoustic (PA) flow cytometry (PAFC) has been developed for in vivo detection of circulating tumor cells and bacteria targeted by nanoparticles. Here, we propose multispectral PAFC with multiple dyes having distinctive absorption spectra as multicolor PA contrast agents. As a first step of our proof-of-concept, we characterized high-speed PAFC capability to monitor the clearance of three dyes (Indocyanine Green [ICG], Methylene Blue [MB], and Trypan Blue [TB]) in an animal model in vivo and in real time. We observed strong dynamic PA signal fluctuations, which can be associated with interactions of dyes with circulating blood cells and plasma proteins. PAFC demonstrated enumeration of circulating red and white blood cells labeled with ICG and MB, respectively, and detection of rare dead cells uptaking TB directly in bloodstream. The possibility for accurate measurements of various dye concentrations including Crystal Violet and Brilliant Green were verified in vitro using complementary to PAFC photothermal (PT) technique and spectrophotometry under batch and flow conditions. We further analyze the potential of integrated PAFC/PT spectroscopy with multiple dyes for rapid and accurate measurements of circulating blood volume without a priori information on hemoglobin content, which is impossible with existing optical techniques. This is important in many medical conditions including surgery and trauma with extensive blood loss, rapid fluid administration, and transfusion of red blood cells. The potential for developing a robust clinical PAFC prototype that is safe for human, and its applications for studying the liver function are further highlighted.

Drug delivery monitoring by photoacoustic tomography with an ICG encapsulated double emulsion.

The absorption spectrum of indocyanine green (ICG), a nontoxic dye used for medical diagnostics, depends upon its concentration as well as the nature of its environment, i.e., the solvent medium into which it is dissolved. In blood, ICG binds with plasma proteins, thus causing changes in its photoacoustic spectrum. We successfully encapsulated ICG in an ultrasound-triggerable perfluorocarbon double emulsion that prevents ICG from binding with plasma proteins. Photoacoustic spectral measurements on point target as well as 2-D photoacoustic images of blood vessels revealed that the photoacoustic spectrum changes significantly in blood when the ICG-loaded emulsion undergoes acoustic droplet vaporization (ADV), which is the conversion of liquid droplets into gas bubbles using ultrasound. We propose that these changes in the photoacoustic spectrum of the ICG emulsion in blood, coupled with photoacoustic tomography, could be used to spatially and quantitatively monitor ultrasound initiated drug delivery. In addition, we suggest that the photoacoustic spectral change induced by ultrasound exposure could also be used as contrast in photoacoustic imaging to obtain a background free image.