Assessing changes in regional cerebral hemodynamics in adults with a high-density full-head coverage time-resolved near-infrared spectroscopy device.

Significance: Cerebral oximeters have the potential to detect abnormal cerebral blood oxygenation to allow for early intervention. However, current commercial systems have two major limitations: (1) spatial coverage of only the frontal region, assuming that surgery-related hemodynamic effects are global and (2) susceptibility to extracerebral signal contamination inherent to continuous-wave near-infrared spectroscopy (NIRS). Aim: This work aimed to assess the feasibility of a high-density, time-resolved (tr) NIRS device (Kernel Flow) to monitor regional oxygenation changes across the cerebral cortex during surgery. Approach: The Flow system was assessed using two protocols. First, digital carotid compression was applied to healthy volunteers to cause a rapid oxygenation decrease across the ipsilateral hemisphere without affecting the contralateral side. Next, the system was used on patients undergoing shoulder surgery to provide continuous monitoring of cerebral oxygenation. In both protocols, the improved depth sensitivity of trNIRS was investigated by applying moment analysis. A dynamic wavelet filtering approach was also developed to remove observed temperature-induced signal drifts. Results: In the first protocol (28±5 years; five females, five males), hair significantly impacted regional sensitivity; however, the enhanced depth sensitivity of trNIRS was able to separate brain and scalp responses in the frontal region. Regional sensitivity was improved in the clinical study given the age-related reduction in hair density of the patients (65±15 years; 14 females, 13 males). In five patients who received phenylephrine to treat hypotension, different scalp and brain oxygenation responses were apparent, although no regional differences were observed. Conclusions: The Kernel Flow has promise as an intraoperative neuromonitoring device. Although regional sensitivity was affected by hair color and density, enhanced depth sensitivity of trNIRS was able to resolve differences in scalp and brain oxygenation responses in both protocols.

Near-Infrared-Driven Nanorocket for Rapid and Ultrasensitive Detection of MicroRNA.

Herein, by introducing gold nanostars (AuNSs) as fuel core, a near-infrared-driven nanorocket (NIDNR) with pretty fast walking was exploited for ultrasensitive miRNA detection. Compared with traditional nanomaterials-comprised nanomachines (NMs), the NIDNR possesses much better kinetic and thermodynamic performance owing to the extra photothermal driving force from localized surface plasmon (LSP). Impressively, the whole reaction time of NIDNR down to 15 min was realized, which is almost more than 8 times beyond those of conventional DNA-based NMs. This way, the inherent obstacle of traditional NMs, including long reaction time and low efficiency, could be easily addressed. As a proof of concept, the NIDNR was successfully applied to develop an electrochemical biosensing platform for rapid and sensitive detection of miRNA with an LOD down to 2.95 aM and achieved the real-time assay of real biological samples from human hepatocellular carcinoma cells (MHCC97L) and HeLa, thus providing an innovative insight to design more versatile DNA nanomachines for ultimate application in biosensing platform construction and clinical sample detection.

Cost-Effectiveness of Vioptix versus Clinical Examination for Flap Monitoring of Autologous Free Tissue Breast Reconstruction.

BACKGROUND: Vioptix is a near-infrared spectroscopy tissue oximetry technology that allows for noninvasive monitoring of flap perfusion. Despite the reported benefits of Vioptix, the cost-effectiveness of this flap monitoring technology has not been compared to clinical examination alone. METHODS: A cost-effectiveness model, from the patient perspective, was constructed with two treatment arms: clinical examination versus clinical examination combined with Vioptix for flap monitoring after autologous, free flap breast reconstruction. Costs, utilities, and other model inputs were identified from the literature. One-way and probabilistic sensitivity analyses were performed. Gamma distributions were created for cost variables, and beta distributions were created for probability variables. An incremental cost-effectiveness ratio under $50,000 per quality-adjusted life-year (QALY) was considered cost-effective. All analyses were performed using TreeAge Pro (Williamstown, Mass.). RESULTS: Mean cost of autologous free tissue transfer breast reconstruction with clinical examination-based flap monitoring was found to be $37,561 with an effectiveness of 0.79, whereas the mean cost of clinical examination with Vioptix for flap monitoring was $39,361 with effectiveness of 0.82. This yielded an incremental cost-effectiveness ratio of $60,507 for clinical examination combined with Vioptix for flap monitoring. One-way sensitivity analysis revealed that clinical examination with Vioptix became cost-effective when the cost of Vioptix was less than $1487. Probabilistic sensitivity analysis found that clinical examination was cost-effective in 86.5 percent of cases. CONCLUSION: Although clinical examination combined with Vioptix is minimally more effective for flap monitoring after autologous, free flap breast reconstruction, clinical examination alone is the more cost-effective flap monitoring option.

Initial clinical experiences using the intraoperative probe-based parathyroid autofluorescence identification system-PTeye™ during thyroid and parathyroid procedures.

BACKGROUND AND OBJECTIVE: The Food and Drug Administration has cleared a probe-based near-infrared autofluorescence (NIRAF) detection system called PTeye™ as an adjunct tool for label-free intraoperative parathyroid gland (PG) identification. Since PTeye™ has been investigated only in a "blinded" manner to date, this study describes the preliminary impressions of PTeye™ when used by surgeons without being blinded to the device output. METHODS: Patients undergoing thyroid and parathyroid procedures were prospectively recruited. Target tissues were intraoperatively assessed with PTeye™. The surgeon's confidence in PG identification was recorded concomitantly with NIRAF parameters that were output in real-time from PTeye™. RESULTS: A retrospective review of prospectively collected data on 83 patients was performed. PTeye™ was used for interrogating 336 target tissues in 46 parathyroid and 37 thyroid procedures. PTeye™ yielded an overall accuracy of 94.3% with a positive predictive value of 93.0% and a negative predictive value of 100%. An increase in confidence for intraoperative PG identification with PTeye™ was observed by all three participating high-volume surgeons, irrespective of their level of accrued surgical experience. CONCLUSIONS: Probe-based NIRAF detection with PTeye™ can be a valuable adjunct device to intraoperatively identify PGs for surgeons of varied training and experience.

SiPM-based gamma detector with a central GRIN lens for a visible/NIRF/gamma multi-modal laparoscope.

Intraoperative imaging has been studied using conventional devices such as near infrared (NIR) optical probes and gamma probes. However, these devices have limited depth penetration and spatial resolution. In a previous study, we realized a multi-modal endoscopic system. However, charge-coupled device (CCD)-based gamma imaging required long acquisition times and lacked gamma energy information. A silicon photomultiplier (SiPM)-based gamma detector is implemented in a multi-modal laparoscope herein. A gradient index (GRIN) lens and CCD are used to transfer and readout visible and NIR photons. The feasibility of in-vivo sentinel lymph node (SLN) mapping was successfully performed with the proposed system.

Effect of Formalin Fixation for Near-Infrared Fluorescence Imaging with an Antibody-Dye Conjugate in Head and Neck Cancer Patients.

PURPOSE: This study evaluated the effect of formalin fixation for near-infrared (NIR) fluorescence imaging of an antibody-dye complex (panitumumab-IRDye800CW) that was intravenously administered to patients with head and neck squamous cell carcinoma (HNSCC) scheduled to undergo surgery of curative intent. PROCEDURES: HNSCC patients were infused with 25 or 50 mg of panitumumab-IRDye800CW followed by surgery 1-5 days later. Following resection, primary tumor specimens were imaged in a closed-field fluorescence imaging device, before and after formalin fixation. The fluorescence images of formalin-fixed specimens were compared with images prior to formalin fixation. Regions of interest were drawn on the primary tumor and on the adjacent normal tissue on the fluorescence images. The mean fluorescence intensity (MFI) and tumor-to-background ratios (TBRs) of the fresh and formalin-fixed tissues were compared. RESULTS: Of the 30 enrolled patients, 20 tissue specimens were eligible for this study. Formalin fixation led to an average of 10 % shrinkage in tumor specimen size (p < 0.0001). Tumor MFI in formalin-fixed specimens was on average 10.9 % lower than that in the fresh specimens (p = 0.0002). However, no statistical difference was found between the TBRs of the fresh specimens and those of the formalin-fixed specimens (p = 0.85). CONCLUSIONS: Despite the 11 % decrease in MFI between fresh and formalin-fixed tissue specimens, the relative difference between tumor and normal tissue as measured in TBR remained unchanged. This data suggests that evaluation of formalin-fixed tissue for assessing the accuracy of fluorescence-guided surgery approaches could provide a valid, yet more flexible, alternative to fresh tissue analysis. TRIAL REGISTRATION: NCT02415881.

Current state of intraoperative use of near infrared fluorescence for parathyroid identification and preservation.

BACKGROUND: Finding and preserving normal parathyroid glands or localizing and removing diseased parathyroid glands are crucial steps to successful thyroid and parathyroid operations. Using near-infrared fluorescence detection to identify parathyroid glands during thyroid and parathyroid operations has lately gained widespread recognition, with 2 Food and Drug Administration-cleared devices currently in the market. We aim to update the endocrine surgery community on how near-infrared fluorescence detection can be most optimally used for rapid intraoperative parathyroid gland identification or preservation. METHODS: A literature review was performed using the key terms: "parathyroid," "near infrared," and "fluorescence" in relevant search engines. Based on the reviewed literature and expert surgeons' opinions, recommendations were formulated for applying near-infrared fluorescence detection to identify or preserve parathyroid glands during cervical endocrine surgery. RESULTS: The scope of near-infrared fluorescence detection can be broadly categorized into (1) using near-infrared auto-fluorescence to identify or locate both healthy and diseased parathyroid glands, and (2) using contrast-enhanced near-infrared fluorescence to evaluate parathyroid gland perfusion. The benefits and pitfalls for both near-infrared-based approaches are described herein. CONCLUSION: Near-infrared fluorescence detection appears helpful for identification and likely preservation of parathyroid glands. We hope these recommendations will be valuable to the practicing endocrine surgeon as they consider incorporating these intraoperative adjuncts in their surgical practice.

Noninvasive Monitoring of Deep Tissue Oxygenation in Buried Flaps by Time-Resolved Near-Infrared Spectroscopy in Pigs.

BACKGROUND: Flap monitoring in reconstructive surgery is particularly important because flap failure is a dramatic event for the patient and for the medical team. Noninvasive deep tissue oxygenation monitoring is a challenge. The aim of this experimental study was to assess the performance of time-resolved near-infrared spectroscopy compared with continuous-wave near-infrared spectroscopy and with invasive oxygen partial pressure measurement in pigs. METHODS: Thirty fasciocutaneous flaps based on the superficial epigastric inferior pedicle were harvested and buried under the transcutaneous dorsal muscle (approximately 1 cm thick). An optical probe was placed on the skin above each buried flap. For each pig, two buried flaps were performed, one submitted to arterial occlusion and one to venous occlusion. Oxyhemoglobin and deoxyhemoglobin concentrations were observed for over 40 minutes before clamping, almost 20 minutes during clamping and during a period of release of approximately 20 minutes. Variations in time-resolved near-infrared spectroscopy were compared to the oxygen partial pressure and continuous-wave near-infrared spectroscopy variations. RESULTS: All vascular events were detected by the time-resolved near-infrared spectroscopy. During arterial clamping, oxyhemoglobin decreased rapidly, whereas deoxyhemoglobin increased moderately. The divergence of oxyhemoglobin and deoxyhemoglobin curves indicated arterial occlusion. During venous clamping, deoxyhemoglobin increased, whereas oxyhemoglobin increased briefly then remained stable or decreased moderately. The initial increases in the oxyhemoglobin and deoxyhemoglobin curves indicated venous occlusion. Oxygen partial pressure failed to detect vascular events in three cases. Continuous-wave near-infrared spectroscopy could not clearly identify vascular occlusions. CONCLUSIONS: Thus, the authors demonstrated the relevance of time-resolved near-infrared spectroscopy to buried flap monitoring. Time-resolved near-infrared spectroscopy could differentiate between arterial occlusion and venous occlusion.

The Use of Near-Infrared Light-Emitting Fluorescent Nanodiamond Particles to Detect Ebola Virus Glycoprotein: Technology Development and Proof of Principle.

BACKGROUND: There is a dire need for rapid diagnostic tests of high sensitivity, efficiency, and point-of-test reporting capability to mitigate lethal viral epidemic outbreaks. PURPOSE: To develop a new operating system within the lateral flow assay (LFA) format for Ebola virus (EBOV), based on fluorescent nanodiamond particles (FNDP) nitrogen vacancy (NV) emitting near-infrared (NIR) light. Specifically, we aimed to detail technical issues and the feasibility of mobilizing FNDP-NV on nitrocellulose membranes (NCM) and capturing them at test and control lines. METHODS: FNDP-NV-200nm, 400nm or 800nm were linked to anti-EBOV glycoprotein (GP) monoclonal antibodies (mAb) and tested for LFA performance by monitoring NIR emissions using an in vivo imaging system or optoelectronic device (OED). Anti-EBOV recombinant glycoprotein (GP) humanized mAb c13C6 was linked to FNDP-NV-200nm for the mobile phase; and a second anti-GP mouse mAb, 6D8, was printed on NCM at the test line. Goat anti-human IgG (GAH-IgG) served as a nonspecific antibody for conjugated FNDP-NV-200nm at the control line. RESULTS: FNDP-NV-200nm-c13C6 specifically and dose-dependently bound to recombinant EBOV GP in vitro and was effectively captured in a sandwich configuration at the test line by mAb 6D8. FNDP-NV-200nm-c13C6 was captured on the control line by GAH-IgG. The OED quantitative analysis of NIR (obtained in less than 1 minute) was further validated by an in vivo imaging system. CONCLUSION: FNDP-NV-200nm performance as a reporter for EBOV GP rapid diagnostic tests suggests an opportunity to replace contemporary visual tests for EBOV GP and other highly lethal viral pathogens. Mobile, battery-operated OED adds portability, quantitative data, rapid data collection, and point-of-test reporting capability. Further development of FNDP-NV-200nm within a LFA format is justified.

Shortwave-infrared meso-patterned imaging enables label-free mapping of tissue water and lipid content.

Water and lipids are key participants in many biological processes, but there are few non-invasive methods that provide quantification of these components in vivo, and none that can isolate and quantify lipids in the blood. Here we develop a new imaging modality termed shortwave infrared meso-patterned imaging (SWIR-MPI) to provide label-free, non-contact, spatial mapping of water and lipid concentrations in tissue. The method utilizes patterned hyperspectral illumination to target chromophore absorption bands in the 900-1,300 nm wavelength range. We use SWIR-MPI to monitor clinically important physiological processes including edema, inflammation, and tumor lipid heterogeneity in preclinical models. We also show that SWIR-MPI can spatially map blood-lipids in humans, representing an example of non-invasive and contact-free measurements of in vivo blood lipids. Together, these results highlight the potential of SWIR-MPI to enable new capabilities in fundamental studies and clinical monitoring of major conditions including obesity, cancer, and cardiovascular disease.

Towards a Portable Platform Integrated With Multispectral Noncontact Probes for Delineating Normal and Breast Cancer Tissue Based on Near-Infrared Spectroscopy.

Currently, the confirmation of diagnosis of breast cancer is made by microscopic examination of an ultra-thin slice of a needle biopsy specimen. This slice is conventionally formalin-fixed and stained with hematoxylin-eosin and visually examined under a light microscope. This process is labor-intensive and requires highly skilled doctors (pathologists). In this paper, we report a novel tool based on near-infrared spectroscopy (Spectral-IRDx) which is a portable, non-contact, and cost-effective system and could provide a rapid and accurate diagnosis of cancer. The Spectral-IRDx tool performs absorption spectroscopy at near-infrared (NIR) wavelengths of 850, 935, and 1060 nm. We measure normalized detected voltage (Vdn) with the tool in 10 deparaffinized breast biopsy tissue samples, 5 of which were cancer (C) and 5 were normal (N) tissues. The difference in Vdn at 935 nm and 1060 nm between cancer and normal tissues is statistically significant with p-values of 0.0038 and 0.0022 respectively. Absorption contrast factor (N/C) of 1.303, 1.551, and 1.45 are observed for 850, 935, and 1060 nm respectively. The volume fraction contrast (N/C) of lipids and collagens are reported as 1.28 and 1.10 respectively. Higher absorption contrast factor (N/C) and volume fraction contrast (N/C) signifies higher concentration of lipids in normal tissues as compared to cancerous tissues, a basis for delineation. These preliminary results support the envisioned concept for noninvasive and noncarcinogenic NIR-based breast cancer diagnostic platform, which will be tested using a larger number of samples.

A low-cost, wireless near-infrared spectroscopy device detects the presence of lower extremity atherosclerosis as measured by computed tomographic angiography and characterizes walking impairment in peripheral artery disease.

BACKGROUND: Patients with peripheral artery disease (PAD) who experience intermittent claudication report a range of symptoms. Patients with symptoms other than classically described intermittent claudication may be at the highest risk for functional decline and mobility loss. Therefore, technologies allowing for characterization of PAD severity are desirable. Near-infrared spectroscopy (NIRS) allows for measurements of muscle heme oxygen saturation (StO2) during exercise. We hypothesized lower extremities affected by PAD would exhibit distinct NIRS profiles as measured by a low-cost, wireless NIRS device and that NIRS during exercise predicts walking limitation. METHODS: We recruited 40 patients with PAD and 10 control participants. All patients with PAD completed a computed tomographic angiography, 6-minute walk test, and a standardized treadmill test. Controls completed a 540-second treadmill test for comparison. StO2 measurements were continuously taken from the gastrocnemius during exercise. Variables were analyzed by Fischer's exact, χ2, Wilcoxon rank-sum, and Kruskal-Wallis tests as appropriate. Correlations were assessed by partial Spearman correlation coefficients adjusted for occlusive disease pattern. RESULTS: Patients with PAD experienced claudication onset at a median of 108 seconds with a median peak walking time of 288 seconds. The baseline StO2 was similar between PAD and control. The StO2 of PAD and control participants dropped below baseline at a median of 1 and 104 seconds of exercise, respectively (P < .0001). Patients with PAD reached minimum StO2 earlier than control participants (119 seconds vs 522 seconds, respectively; P < .001) and experienced a greater change in StO2 at 1 minute of exercise (-73.2% vs 8.3%; P < .0001) and a greater decrease at minimum exercise StO2 (-83.4% vs -16.1%; P < .0001). For patients with PAD, peak walking time, and 6-minute walking distance correlated with percent change in StO2 at 1 minute of exercise (r = -0.76 and -0.67, respectively; P < .001) and time to minimum StO2 (r = 0.79 and 0.70, respectively; P < .0001). CONCLUSIONS: In this initial evaluation of a novel, low-cost NIRS device, lower extremities affected by PAD exhibited characteristic changes in calf muscle StO2, which differentiated them from healthy controls and were strongly correlated with walking impairment. These findings confirm and expand on previous work demonstrating the potential clinical value of NIRS devices and the need for further research investigating the ability of low-cost NIRS technology to evaluate, diagnose, and monitor treatment response in PAD.

Detecting the Near Infrared Autofluorescence of the Human Parathyroid: Hype or Opportunity?

OBJECTIVE: With the recent approval of 2 NIRAF-based devices for label-free identification of PG by the Food and Drug Administration, it becomes crucial to educate the surgical community on the realistic scope of this emerging technology. Here, we have compiled a review of studies that utilize NIRAF and present a critical appraisal of this technique for intraoperative PG detection. BACKGROUND: Failure to visualize PGs could lead to accidental damage/excision of healthy PGs or inability to localize diseased PGs, resulting in postsurgical complications. The discovery that PGs have NIRAF led to new avenues for intraoperatively identifying PGs with high accuracy in real-time. METHODS: Using the following key terms: "parathyroid, near infrared, autofluorescence" in various search engines such as PubMed and Google Scholar, we identified various publications relevant to this review of NIRAF as a technique for PG identification. Articles were excluded if they focused solely on contrast agents, served as commentaries/overviews on NIRAF or were not written in English. RESULTS: To date, studies have investigated the potential of NIRAF detection for (i) identifying PG tissues intraoperatively, (ii) locating PGs before or after dissection, (iii) distinguishing healthy from diseased PGs, and (iv) minimizing postoperative hypocalcemia after total thyroidectomy. CONCLUSIONS: Because NIRAF-based identification of PG is noninvasive and label-free, the popularity of this approach has considerably surged. As the present limitations of various technologies capable of NIRAF detection are identified, we anticipate that newer device iterations will continue to be developed enhancing the current merits of these modalities to aid surgeons in identifying and preserving PGs. However, more concrete and long-term outcome studies with these modalities are essential to determine the impact of this technique on patient outcome and actual cost-benefits.

Methylene Blue-Based Near-Infrared Fluorescence Imaging for Breast Cancer Visualization in Resected Human Tissues.

Breast-conserving surgery is facing the challenge of objective tumor margin identification intraoperatively. Near-infrared fluorescence imaging would be an ideal approach to visualize tumor margins during surgeries. In this preliminary study, the feasibility of methylene blue-based near-infrared fluorescence imaging technique for breast cancer detection was assessed in resected human breast specimens after breast cancer surgeries. Thirty patients with breast cancer scheduled for surgical treatment were enrolled, including 10 patients with preoperative chemotherapy and 20 patients without. Each of them received an injection of 1 mg/kg methylene blue intravenously 3 hours before the surgery. Then, a home-developed methylene blue-specific near-infrared fluorescence imaging system was employed to image the resected breast tissues and identify the tumor by the fluorescence contrast. Specimens were taken for pathological examinations as the reference. There were no severe adverse events attributable to methylene blue. Of 20 patients, who did not receive preoperative chemotherapy, 16 exhibited fluorescent contrast on their resected tissues (signal-to-background ratio: 1.94 ± 0.71). In contrast, tumors were identified in 3 of 10 specimens from patients who underwent preoperative chemotherapy (signal-to-background ratio: 1.63 ± 0.38). A total of 35 tissues were sampled from 30 specimens. Besides 30 tumor samples, 5 more suspicious samples with fluorescence signal were confirmed to be benign hemorrhagic tissues. Therefore, a sensitivity of 0.63 and a positive predictive value of 0.79 were achieved by the methylene blue fluorescence imaging strategy. Here, we demonstrate the feasibility of using methylene blue fluorescence imaging to identify breast cancer. Preoperative chemotherapy had an impact on imaging effect, which may reduce the detection rate. After all, methylene blue fluorescence imaging has great potential to be used into breast-conserving surgery for tumor-positive margins detection, but further clinical trial study is needed ( http://www.chictr.org.cn/ Clinical Trial Registry ID: ChiCTR1800015400, Near-infrared fluorescence imaging applied in breast cancer identification with methylene blue).

Feasibility study for rapid near-infrared spectroscopic identification of different gallbladder diseases by direct analysis of bile juice.

A whole-sample-covering near-infrared (NIR) spectroscopy scheme has been adopted for the simple drop-and-dry measurement of raw bile juice for the identification of gallbladder (GB) diseases of stone, polyp, and cancer. For reproducible measurement, a non-NIR absorbing polytetrafluoroethylene (PTFE) providing a hydrophobic surface was chosen as a substrate to form bile juice droplets of a consistent shape. To ensure representative spectroscopic sampling, NIR radiation illuminated the whole area of the dried sample for spectral acquisition. The NIR band shapes and relative band intensities of GB cancer differed moderately from those of GB stone and GB polyp. The composition of GB cancer samples was presumed to be dissimilar from other sample compositions. Differentiation between GB polyp and GB stone, however, was less facile; nevertheless, in the case of GB polyp samples, the obtained NIR features were informative in the identification of various pathological conditions such as adenomyomatosis (abnormal growth of epidermal tissue) and hepatitis B. To elucidate the NIR features of bile juice samples, separate NIR spectra of major bile constituents such as conjugated bile salts, lecithin, cholesterol, and albumin were analyzed. The demonstrated NIR spectroscopy scheme requiring no sample pretreatment or separation of bile juice could be useful for fast bile juice-based screening of GB diseases, especially the identification of early GB cancer.

Raman Spectroscopy for Rapid Evaluation of Surgical Margins during Breast Cancer Lumpectomy.

Failure to precisely distinguish malignant from healthy tissue has severe implications for breast cancer surgical outcomes. Clinical prognoses depend on precisely distinguishing healthy from malignant tissue during surgery. Laser Raman spectroscopy (LRS) has been previously shown to differentiate benign from malignant tissue in real time. However, the cost, assembly effort, and technical expertise needed for construction and implementation of the technique have prohibited widespread adoption. Recently, Raman spectrometers have been developed for non-medical uses and have become commercially available and affordable. Here we demonstrate that this current generation of Raman spectrometers can readily identify cancer in breast surgical specimens. We evaluated two commercially available, portable, near-infrared Raman systems operating at excitation wavelengths of either 785 nm or 1064 nm, collecting a total of 164 Raman spectra from cancerous, benign, and transitional regions of resected breast tissue from six patients undergoing mastectomy. The spectra were classified using standard multivariate statistical techniques. We identified a minimal set of spectral bands sufficient to reliably distinguish between healthy and malignant tissue using either the 1064 nm or 785 nm system. Our results indicate that current generation Raman spectrometers can be used as a rapid diagnostic technique distinguishing benign from malignant tissue during surgery.

Near-infrared in vitro measurements of photosystem I cofactors and electron-transfer partners with a recently developed spectrophotometer.

A kinetic-LED-array-spectrophotometer (Klas) was recently developed for measuring in vivo redox changes of P700, plastocyanin (PCy), and ferredoxin (Fd) in the near-infrared (NIR). This spectrophotometer is used in the present work for in vitro light-induced measurements with various combinations of photosystem I (PSI) from tobacco and two different cyanobacteria, spinach plastocyanin, cyanobacterial cytochrome c6 (cyt. c6), and Fd. It is shown that cyt. c6 oxidation contributes to the NIR absorption changes. The reduction of (FAFB), the terminal electron acceptor of PSI, was also observed and the shape of the (FAFB) NIR difference spectrum is similar to that of Fd. The NIR difference spectra of the electron-transfer cofactors were compared between different organisms and to those previously measured in vivo, whereas the relative absorption coefficients of all cofactors were determined by using single PSI turnover conditions. Thus, the (840 nm minus 965 nm) extinction coefficients of the light-induced species (oxidized minus reduced for PC and cyt. c6, reduced minus oxidized for (FAFB), and Fd) were determined with values of 0.207 ± 0.004, - 0.033 ± 0.006, - 0.036 ± 0.008, and - 0.021 ± 0.005 for PCy, cyt. c6, (FAFB) (single reduction), and Fd, respectively, by taking a reference value of + 1 for P700+. The fact that the NIR P700 coefficient is larger than that of PCy and much larger than that of other contributing species, combined with the observed variability in the NIR P700 spectral shape, emphasizes that deconvolution of NIR signals into different components requires a very precise determination of the P700 spectrum.

Medulla loss of scalp hair in breast cancer patients determined by near-infrared microscopy.

Inexpensive near-infrared microscopy (NIRM) was developed as a convenient technique to detect the medulla loss of scalp hair while reducing analytical time with easy sample preparation, leading to a field screening tool for breast cancer. NIRM has been evaluated as an alternative to synchrotron-based nanoscopy and to the relatively expensive method of conventional infrared microscopy to determine the degree and pattern of medulla loss of scalp hairs of patients with breast cancer and benign diseases, as well as normal healthy individuals. NIR imaging showed a strong, scattering-based hyperintense contrast of the medulla compared to the fully attenuated cortex in medullated healthy hair. Complete medulla loss (CML) per hair strand was more extensively (60.9 ± 10.2 %) (p < 0.001) detected in the hair of all cancer patients than in the hair of either healthy individuals (less than 3.7 ± 7.5%) or those with benign disease (30.6 ± 5.9 % ), suggesting a potential biomarker for breast cancer diagnosis. The medulla structure was retained mostly in the hair of age-matched healthy individuals, but discontinuous medulla loss was observed concomitantly with less CML in fibroadenoma patients. Potentially, compact NIRM modules can be integrated into a mobile platform as point-of-care technology for breast cancer screening.