Project description:Contrast-free autofluorescence (AF) of the parathyroid glands (PTGs) and thyroid tissue occurs in the near-infrared (NIR) spectrum on excitation by light in the upper range of the visible spectrum or lower NIR spectrum. In vivo, PTGs autofluoresce more brightly than thyroid (by a factor of 2-20 times) and appear as a bright spot against surrounding thyroid, muscle or fat on a processed image which is generated in real-time. NIR-AF of PTGs was first described in 2009 although NIR-AF had previously been used in several other clinical applications. Since then there has been a great amount of interest in the use of NIR-AF in thyroid and parathyroid surgery with over 25 published reports of the utilisation of both self-built and proprietary NIR-AF devices in neck endocrine surgery. All of these reports have confirmed the feasibility of NIR-AF intraoperatively and its ability to detect PTGs, although the reported accuracy varies from 90-100%. Reports of the effect of NIR-AF on relevant clinical endpoints i.e., post-operative hypoparathyroidism in thyroidectomy and persistent disease in parathyroidectomy are however scant. There has been one multicentre clinical trial of NIR-AF in thyroidectomy but this did not report clinical outcomes and two single-centre, non-randomised studies which did report post-operative hypoparathyroidism but with differing results: one showing no benefit in 106 NIR-AF vs. 163 controls and one, a reduction of early hypocalcaemia from 20% to 5% in 93 NIR-AF patients vs. 420 controls. There were only 2 cases of permanent hypoparathyroidism across both studies and therefore no significant observable difference in this key outcome variable. In parathyroidectomy, possible variability of the AF signal due to composition of a PTG adenoma, secondary/tertiary disease and MEN1 as well as depth-penetration preventing detection of sub-surface PTGs would imply that NIR-AF in its current form is not well-placed to improve cure-rates in hyperparathyroidism, which may already be as high as 98%. Thus far, no study has addressed this. Despite the promising results of NIR-AF, the absence of data demonstrating an improvement in outcomes and the cost of its use currently limit its use in routine clinical practice, especially in a publicly funded healthcare system with budgetary constraints. However, it can be utilised in research settings and this should be undertaken within the context of well-designed and conducted randomised, multi-centre, appropriately powered studies, which will assist in establishing its role in neck endocrine surgery.
Project description:ObjectivesCompared to adult patients undergoing thyroid surgery, pediatric patients have higher rates of hypoparathyroidism often related to parathyroid gland (PG) inadvertent injury or devascularization. Previous studies have shown that near-infrared-autofluorescence (NIRAF) can be reliably used intraoperatively for label-free parathyroid identification, but all prior studies have been performed in adult patients. In this study, we assess the utility and accuracy of NIRAF with a fiber-optic probe-based system to identify PGs in pediatric patients undergoing thyroidectomy or parathyroidectomy.MethodsAll pediatric patients (under 18 years of age) undergoing thyroidectomy or parathyroidectomy were enrolled in this IRB-approved study. The surgeon's visual assessment of tissues was first noted and the surgeon's confidence level in the tissue identified was recorded. A fiber-optic probe was then used to illuminate tissues-of-interest with a wavelength of 785 nm and resulting NIRAF intensities from these tissues were measured while the surgeon was blinded to results.ResultsNIRAF intensities were measured intraoperatively in 19 pediatric patients. Normalized NIRAF intensities for PGs (3.63 ± 2.47) were significantly higher than that of thyroid (0.99 ± 0.36, p < 0.001) and other surrounding soft tissues (0.86 ± 0.40, p < 0.001). Based on the PG identification ratio threshold of 1.2, NIRAF yielded a detection rate of 95.8% (46/48 pediatric PGs).ConclusionOur findings indicate that NIRAF detection can potentially be a valuable and non-invasive technique to identify PGs during neck operations in the pediatric population. To our knowledge, this is the first study in children to assess the accuracy of probe-based NIRAF detection for intraoperative parathyroid identification.Level of evidenceLevel 4 Laryngoscope, 133:3208-3215, 2023.
Project description:Parathyroid allotransplantation is a burgeoning treatment for severe hypoparathyroidism. Deceased donor parathyroid gland (PTG) procurement can be technically challenging due to lack of normal intraoperative landmarks and exposure constraints in the neck of organ donors. In this study, we assessed standard 4-gland exposure in situ and en bloc surgical techniques for PTG procurement and ex vivo near-infrared autofluorescence (NIRAF) imaging for identification of PTGs during organ recovery.MethodsResearch tissue consent was obtained from organ donors or donor families for PTG procurement. All donors were normocalcemic, brain-dead, solid organ donors between 18 and 65 y of age. PTGs were procured initially using a standard 4-gland exposure technique in situ and subsequently using a novel en bloc resection technique after systemic organ preservation flushing. Parathyroid tissue was stored at 4 °C in the University of Wisconsin solution up to 48 h post-procurement. Fluoptics Fluobeam NIRAF camera and Image J software were utilized for quantification of NIRAF signal.ResultsThirty-one brain-dead deceased donor PTG procurements were performed by abdominal transplant surgeons. In the initial 8 deceased donors, a mean of 1.75 glands (±1.48 glands SD) per donor were recovered using the 4-gland in situ technique. Implementation of combined en bloc resection with ex vivo NIRAF imaging in 23 consecutive donors yielded a mean of 3.60 glands (±0.4 SD) recovered per donor (P < 0.0001). Quantification of NIRAF integrated density signal demonstrated >1-fold log difference in PTG (2.13 × 105 pixels) versus surrounding anterior neck structures (1.9 × 104 pixels; P < 0.0001). PTGs maintain distinct NIRAF signal from the time of recovery (1.88 × 105 pixels) up to 48 h post-procurement (1.55 × 105 pixels) in organ preservation cold storage (P = 0.34).ConclusionsThe use of an en bloc surgical technique with ex vivo NIRAF imaging significantly enhances the identification and recovery of PTG from deceased donors.
Project description:BackgroundNear infrared autofluorescence (NIRAF) detection has previously demonstrated significant potential for real-time parathyroid gland identification. However, the performance of a NIRAF detection device - PTeye® - remains to be evaluated relative to a surgeon's own ability to identify parathyroid glands.MethodsPatients eligible for thyroidectomy and/or parathyroidectomy were enrolled under 6 endocrine surgeons at 3 high-volume institutions. Participating surgeons were categorized based on years of experience. All surgeons were blinded to output of PTeye® when identifying tissues. The surgeon's performance for parathyroid discrimination was then compared with PTeye®. Histology served as gold standard for excised specimens, while expert surgeon's opinion was used to validate in-situ tissues.ResultsPTeye® achieved 92.7% accuracy across 167 patients recruited. Junior surgeons (<5 years of experience) were found to have lower confidence in parathyroid identification and higher tissue misclassification rate per specimen when compared to PTeye® and senior surgeons (>10 years of experience).ConclusionsNIRAF detection with PTeye® can be a valuable intraoperative adjunct technology to aid in parathyroid identification for surgeons.
Project description:Intraoperative localisation and preservation of parathyroid glands improves outcomes following thyroid and parathyroid surgery. This can be facilitated by fluorescent imaging and methylene blue; a fluorophore is thought to be taken up avidly by parathyroid glands. This preliminary study aims to identify the optimum dose of methylene blue (MB), fluorescent patterns of thyroid and parathyroid glands and develop a protocol for the use of intravenous MB emitted fluorescence to enable parathyroid identification.This is a phase 1b, interventional study (NCT02089542) involving 41 patients undergoing thyroid and/or parathyroid surgery. After exposure of the thyroid and/or parathyroid gland(s), intravenous boluses of between 0.05 and 0.5 mg/kg of MB were injected. Fluobeam® (a hand held fluorescence real-time imager) was used to record fluorescence from the operating field prior and up to 10 min following administration.The optimum dose of MB to visualise thyroid and parathyroid glands was 0.4 mg/kg body weight. The median time to onset of fluorescence was 23 and 22 s and the median time to peak fluorescence was 41.5 and 40 s, respectively. The peak fluorescence for thyroid and parathyroid glands compared to muscle were 2.6 and 4.3, respectively. Parathyroid auto-fluorescence prior to methylene blue injection was commonly observed.A clinical protocol for detection of fluorescence from MB during thyroid and parathyroid surgery is presented. Parathyroids (especially enlarged glands) fluoresce more intensely than thyroid glands. Auto-fluorescence may aid parathyroid detection, but MB fluorescence is needed to demonstrate viability.
Project description:In over 30% of all thyroid surgeries, complications arise from transient and definitive hypoparathyroidism, underscoring the need for real-time identification and preservation of parathyroid glands (PGs). Here, we evaluate the promising intraoperative optical technologies available for the identification, preservation, and functional assessment of PGs to enhance endocrine surgery. We performed a review of the literature to identify published studies on fluorescence imaging in thyroid and parathyroid surgery. Fluorescence imaging is a well-demonstrated approach for both in vivo and in vitro localization of specific cells or tissues, and is gaining popularity as a technique to detect PGs during endocrine surgery. Autofluorescence (AF) imaging and indocyanine green (ICG) angiography are two emerging optical techniques to improve outcomes in thyroid and parathyroid surgeries. Near-infrared-guided technology has significantly contributed to the localization of PGs, through the detection of glandular AF. Perfusion through the PGs can be visualized with ICG, which can also reveal the blood supply after dissection. Near infrared AF and ICG angiography, providing a valuable spatial and anatomical information, can decrease the incidence of complications in thyroid surgery.
Project description:BACKGROUND:Fundus autofluorescence is a non-invasive imaging technique in ophthalmology. Conventionally, short-wavelength autofluorescence (SW-AF) is used for detection of lipofuscin, a byproduct of the visual cycle which accumulates with age or disease in the retinal pigment epithelium (RPE). Furthermore, near-infrared autofluorescence (NIR-AF) is used as a marker for RPE and choroidal melanin, but contribution of lipofuscin to the NIR-AF signal is unclear. METHODS:We employed fluorescence microscopy to investigate NIR-AF properties of melanosomes, lipofuscin and melanolipofuscin granules in histologic sections of wildtype and Abca4-/- mouse eyes, the latter having increased lipofuscin, as well as aged human donor eyes. Differentiation between these pigments was verified by analytical electron microscopy. To investigate the influence of oxidative and photic stress we used an in vitro model with isolated ocular melanosomes and an in vivo phototoxicity mouse model. FINDINGS:We show that NIR-AF is not an intrinsic property of melanin, but rather increases with age and after photic or oxidative stress in mice and isolated melanosomes. Furthermore, when lipofuscin levels are high, lipofuscin granules also show NIR-AF, as confirmed by correlative fluorescence and electron microscopy in human tissue. However, lipofuscin in albino Abca4-/- mice lacks NIR-AF signals. INTERPRETATION:We suggest that NIR-AF is derived from melanin degradation products that accumulate with time in lipofuscin granules. These findings can help to improve the interpretation of patient fundus autofluorescence data. FUNDING:This work was supported by Bundesministerium für Bildung und Forschung, Deutsche Forschungsgemeinschaft and Chinese Scholarship Council. Major instrumentation used in this work was supported by Deutsche Forschungsgemeinschaft, the European Fund for Regional Development and the state of Baden-Württemberg.
Project description:Background and aimsPrior coronary optical coherence tomography (OCT)-near infrared auto-fluorescence (NIRAF) imaging data has shown a correlation between high-risk morphological features and NIRAF signal intensity. This study aims to understand the histopathological origins of NIRAF in human cadaver coronary arteries.MethodsEx vivo intracoronary OCT-NIRAF imaging was performed on coronary arteries prosected from 23 fresh human cadaver hearts. Arteries with elevated NIRAF were formalin-fixed and paraffin-embedded. Microscopic images of immunostained Glycophorin A (indicating intraplaque hemorrhage) and Sudan Black (indicating ceroid after fixation) stained slides were compared with confocal NIRAF images (ex. 635 nm, em. 655-755 nm) from adjacent unstained slides in each section. Different images from the same section were registered via luminal morphology. Confocal NIRAF-positive 45° sectors were compared to immunohistochemistry and colocalization between NIRAF and intraplaque hemorrhage or ceroid was quantified by Manders' overlap and Dice similarity coefficients.ResultsThirty-one coronary arteries from 14 hearts demonstrated ≥1.5 times higher NIRAF signal than background, and 429 sections were created from them, including 54 sections (12.6%) with high-risk plaques. Within 112 confocal NIRAF-positive 45° sectors, 65 sectors (58.0%) showed both Glycophorin A-positive and Sudan Black-positive, while 7 sectors (6.3%) and 40 sectors (33.6%) only showed Glycophorin A-positive or Sudan black-positive, respectively. A two-tailed McNemar's test showed that Sudan Black more closely corresponded to confocal NIRAF than Glycophorin A (p < 1.0 × 10-6). NIRAF was also found to spatially associate with both Glycophorin A and Sudan Black, with stronger colocalization between Sudan Black and NIRAF (Manders: 0.19 ± 0.15 vs. 0.13 ± 0.14, p < 0.005; Dice: 0.072 ± 0.096 vs. 0.060 ± 0.090, p < 0.01).ConclusionsAs ceroid associates with oxidative stress and intraplaque hemorrhage is implicated in rapid lesion progression, these results suggest that NIRAF provides additional, complementary information to morphologic imaging that may aid in identifying high-risk coronary plaques via translatable intracoronary OCT-NIRAF imaging.
Project description:The growing interest in the use of near-infrared (NIR) radiation for spectroscopy, optical communication, and medical applications spanning both NIR-I (700-900 nm) and NIR-II (900-1700 nm) has driven the need for new NIR light sources. NIR phosphor-converted light-emitting diodes (pc-LEDs) are expected to replace traditional lamps mainly due to their high efficiency and compact design. Broadband NIR phosphors activated by Cr3+ and Cr4+ have attracted significant research interest, offering emission across a wide range from 700 to 1700 nm. In this work, we synthesized a series of Sc2(1-x)Ga2xO3:Cr3+/4+ materials (x = 0-0.2) with broadband NIR-I (Cr3+) and NIR-II (Cr4+) emission. We observed a substantial increase in the intensity of Cr3+ (approximately 77 times) by incorporating Ga3+ ions. Additionally, our investigation revealed that energy transfer occurred between Cr3+ and Cr4+ ions. Configuration diagrams are presented to elucidate the behavior of Cr3+ and Cr4+ ions within the Sc2O3 matrix. We also observed a phase transition at a pressure of 20.2 GPa, resulting in a new unknown phase where Cr3+ luminescence exhibited a high-symmetry environment. Notably, this study presents the pressure-induced shift of NIR Cr4+ luminescence in Sc2(1-x)Ga2xO3:Cr3+/4+. The linear shifts were estimated at 83 ± 3 and 61 ± 6 cm-1/GPa before and after the phase transition. Overall, our findings shed light on the synthesis, luminescent properties, temperature, and high-pressure behavior within the Sc2(1-x)Ga2xO3:Cr3+/4+ materials. This research contributes to the understanding and potential applications of these materials in the development of efficient NIR light sources and other optical devices.
Project description:Different applications of near-infrared fluorescence-guided surgery are very promising, and techniques that help surgeons in intraoperative guidance have been developed, thereby bridging the gap between preoperative imaging and intraoperative visualization and palpation. Thus, these techniques are advantageous in terms of being faster, safer, less invasive, and cheaper. There are a few fluorescent dyes available, but the most commonly used dye is indocyanine green. It can be used in its natural form, but different nanocapsulated and targeted modifications are possible, making this dye more stable and specific. A new active tumor-targeting strategy is the conjugation of indocyanine green nanoparticles with antibodies, making this dye targeted and highly selective to various tumor proteins. In this mini-review, we discuss the application of near-infrared fluorescence-guided techniques in thoracic surgery. During lung surgery, it can help find small, non-palpable, or additional tumor nodules, it is also useful for finding the sentinel lymph node and identifying the proper intersegmental plane for segmentectomies. Furthermore, it can help visualize the thoracic duct, smaller bullae of the lung, phrenic nerve, or pleural nodules. We summarize current applications and provide a framework for future applications and development.