Near-infrared Autofluorescence Imaging Research Articles

Procurement of Deceased Donor Parathyroid Glands With the Aid of Near-infrared Autofluorescence Imaging

Background.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.Methods.Research 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.Results.Thirty-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).Conclusions.The use of an en bloc surgical technique with ex vivo NIRAF imaging significantly enhances the identification and recovery of PTG from deceased donors.

Autofluorescence of parathyroid glands during endocrine surgery with minimally invasive technique.

Accidental injury to the parathyroid glands (PTGs) is common during thyroid and parathyroid surgery. To overcome the limitation of naked eye in identifying the PTGs, intraoperative autofluorescence imaging has been embraced by an increasing number of surgeons. The aim of our study was to describe the technique and assess its utility in clinical practice. Near-infrared (NIR) autofluorescence imaging was carried out during open parathyroid and thyroid surgery in 25 patients (NIR group), while other 26 patients underwent traditional PTG detection based on naked eye alone (NO-NIR group). Primary variables assessed for correlation between traditional approach and autofluorescence were number of PTGs identified and incidence of postoperative hypoparathyroidism (hypoPT). 81.9% of PTGs were detected by means of fluorescence imaging and 74.5% with visual inspection alone, with an average of 2.72 PTGs visualized per patient using NIR imaging versus approximately 2.4 per patient using naked eye (p = 0.38). Considering only the more complex total thyroidectomies (TTs), the difference was almost statistically significant (p = 0.06). Although not statistically significant, the observed postoperative hypoPT rate was lower in the NIR group. Despite the limitations and technical aspects still to be investigated, fluorescence seems to reduce this complication rate by improving the intraoperative detection of the PTGs.

Histopathological correlation of near infrared autofluorescence in human cadaver coronary arteries

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.

Evaluation of Autofluorescence in Identifying Parathyroid Glands by Measuring Parathyroid Hormone in Fine-Needle Biopsy Washings

BackgroundNear-infrared autofluorescence imaging has potentially great value for assisting endocrine surgeons in identifying parathyroid glands and may dramatically change the surgical strategy of endocrine surgeons in thyroid surgery. This study is designed to objectively evaluate the role of near-infrared autofluorescence imaging in identifying parathyroid glands during thyroid surgery by measuring intraoperative parathyroid hormone in fine-needle aspiration biopsy washings.MethodsThis study was conducted at a tertiary referral teaching hospital in China from February 2020 to June 2020. Patients undergoing total thyroidectomy with or without neck lymph node dissection were consecutively included. The surgeon used near-infrared autofluorescence imaging to identify parathyroid glands during thyroid surgery and confirmed suspicious parathyroid tissues by measuring their intraoperative parathyroid hormone. Nanocarbon was injected into the thyroid gland if the thyroid autofluorescence intensity was too strong. The sensitivity and accuracy of near-infrared autofluorescence imaging and vision for identifying parathyroid glands, and the difference in autofluorescence intensity in various tissues were the main outcomes.ResultsOverall, 238 patients completed the trial. Based on the pathological and aIOPTH results, the sensitivity of near-infrared autofluorescence imaging for detecting parathyroid glands (568 of 596 parathyroid glands; 95.30%)was significantly higher than that of vision (517 of 596 parathyroid glands; 86.74%, P<.001). The accuracy of near-infrared autofluorescence imaging (764 of 841 tissues; 90.84%) was significantly higher than that of vision (567 of 841 tissues; 67.42%, P<.001) when the evaluations of certain tissues were inconsistent. There was a significant difference between the autofluorescence intensity of the parathyroid glands and that of the lymph nodes (74.19 ± 17.82 vs 33.97 ± 10.64, P<.001).ConclusionThe use of near-infrared autofluorescence imaging, along with intraoperative parathyroid hormone and nanocarbon for the identification of parathyroid glands in thyroid surgery may increase the number of confirmed parathyroid glands. Using near-infrared autofluorescence imaging can effectively distinguish lymph nodes and parathyroid glands during lymph node dissection.

NPHP1 Full Deletion Causes Nephronophthisis and a Cone-Rod Dystrophy.

To describe in detail the structural and functional phenotype of a patient with cone-rod dystrophy associated with a full deletion of the NPHP1 gene. A 30-year-old male with history of end-stage renal disease (ESRD) presented with progressive vision loss in early adulthood prompting evaluation for retinal disease. Ophthalmic evaluation was performed including, kinetic fields, electroretinography (ERG), spectral domain optical coherence tomography (SD-OCT), fundus auto-fluorescence (FAF), wide-angle fluorescein angiography and near infrared imaging (NIR). Visual acuity was 20/60 in each eye. Fundus examination revealed a subtle bull's-eye maculopathy confirmed with fundus autofluorescence. SD-OCT demonstrated perifoveal loss of the outer retinal layers with structural preservation further peripherally. Testing of retinal function confirmed loss of cone greater than rod sensitivities in a manner that co-localized to structural findings. ERG revealed decreased photopic and scotopic responses. Genetic testing confirmed a homozygous whole gene deletion of the NPHP1 gene. NPHP1-associated retinal degeneration may present as a cone-rod dystrophy in addition to the previously reported rod-predominant phenotypes and can notably be associated with systemic abnormalities, including renal disease. Our work further expands upon the growing literature describing retinal disease associated with systemic ciliopathies.

Intraoperative detection of parathyroid glands by autofluorescence identification using image-based system: report of 15 cases

BackgroundA detection of parathyroid glands by the evaluation of their autofluorescence in the near-infrared spectrum is considered as a promising tool in addition to their visual verification. The aim of this study was to evaluate the role of near-infrared autofluorescence application by using two different image-based systems for the identification of parathyroid glands during surgery of thyroid and parathyroid benign and malignant lesions.MethodsEvaluation of near-infrared autofluorescence was performed in 15 patients by using two different image-based systems equipped with a near-infrared laser camera. Intravenous injection of fluorophore indocyanine green was used for the enhancement of near-infrared autofluorescence signal.ResultsNormal parathyroid glands were identified and mobilized after visual inspection in 12 (80%) patients, which was confirmed by near-infrared autofluorescence evaluation. Confident recognition of parathyroid glands by near-infrared autofluorescence signal and their subsequent distinction from lymph nodes was achieved in two (13%) patients with prior surgery for papillary thyroid carcinoma. In one (7%) case, parathyroid gland was identified as fragments of tissue within the postoperative scarring area by near-infrared autofluorescence evaluation, but not by visual inspection. A less intensive near-infrared autofluorescence signal was detected in the parathyroid gland owing to unintentional excision in one (7%) case. Better signal intensity from parathyroid glands was noticed after changes of the near-infrared camera in Fluobeam 800 image-based system in position to an angle of approximately 45–65° in relation to area of interest in all cases as compared with holding straight on the parathyroid gland. Fluobeam LX demonstrated a good near-infrared autofluorescence signal without any specific changes in the camera angle. Thyroid carcinoma demonstrated low-intensity signal in the case of invasion to thyroid capsule. No fluorescent signal was identified from metastatic, or from normal, lymph nodes.ConclusionsThe application of near-infrared autofluorescence imaging is considered as a useful, but additional, tool for the visual assessment of parathyroid gland in the case of primary neck exploration. The utility of near-infrared autofluorescence imaging for parathyroid detection is increased in the case of repeated surgical intervention owing to increased risk of unintentional parathyroid removal as well as for discrimination of parathyroids from the lymph nodes in cases of thyroid malignancy.

Can near-infrared autofluorescence imaging be used for intraoperative confirmation of parathyroid tissue?

Whether ex vivo autofluorescence (AF) imaging findings could be quantified to intraoperatively differentiate parathyroid tissue has not been reported. Our aim was to assess the ability of AF imaging to confirm parathyroid tissue during thyroidectomy and parathyroidectomy procedures. This was a retrospective Institutional Review Board-approved study. AF signals of specimens imaged ex vivo before submission to pathology during thyroidectomy and parathyroidectomy procedures were quantified. Using receiver operating characteristic (ROC) curves, optimal values for sensitivity/specificity to differentiate parathyroid tissue were calculated. 166 parathyroid and 217 non-parathyroid specimens were analyzed. With surgical drapes as background, the optimal normalized AF intensity threshold to predict parathyroid tissue on ROC curve analysis was 1.72 (86.1% sensitivity, 84.8% specificity, and area under the curve [AUC]: 0.919). The cutoff for 97% sensitivity was 1.31and for 99.1% specificity was 3.16. With Telfa as background, the optimal threshold to predict parathyroid tissue was 1.46 (88.4% sensitivity, 76.8% specificity, and AUC: 0.896). The threshold for 96.8% sensitivity was 1.18and for 98.8% specificity was 2.44. If thresholds for highest specificity were used, 40% of frozen sections to confirm parathyroid tissue could have been avoided. Quantified brightness analysis of ex vivo AF signals may have utility in intraoperative differentiation of parathyroid tissue for 40% of surgical specimens.

Near-Infrared Autofluorescence Imaging May Reduce Temporary Hypoparathyroidism in Patients Undergoing Total Thyroidectomy and Central Neck Dissection.

Background: Near-infrared autofluorescence (NIRAF) imaging is known to reduce the incidence of post-thyroidectomy hypocalcemia. However, there are no studies on how much NIRAF imaging affects the serum parathyroid hormone (PTH) level after surgery. We investigated the changes of the serum PTH level and ionized calcium (iCa.) in patients undergoing total thyroidectomy with central neck dissection (CND). Materials and Methods: This retrospective study with historical control enrolled 542 patients who underwent total thyroidectomy with CND. Patients were divided into two groups: the NIRAF group (261 patients) and the control group (281 patients). PTH and iCa. levels were measured at the hospital stay, 1, 3, and 6 months after surgery. In addition, the number of identified parathyroid glands (PGs), autotransplanted PGs, and the inadvertent resection rate of PGs was evaluated. Results: The incidence of postoperative hypoparathyroidism (PTH <15 pg/mL) was significantly lower in the NIRAF group during the hospitalization (88 patients: 33.7% vs. 131 patients: 46.6%; p = 0.002) and at 1 month postoperatively (23 patients: 8.8% vs. 53 patients: 18.9%; p = 0.001). There was no difference in the permanent hypoparathyroidism rate (6 months after surgery) between the NIRAF group and the control group (4.2% vs. 4.6%; p = 0.816). There was no difference in the incidence of hypocalcemia (iCa. <1.09 mmol/L) (during hospitalization: 6.5% vs. 10.0%; 1 month: 2.3% vs. 2.5%; 3 months: 0.8% vs. 0.7%; 6 months after surgery: 1.1% vs. 1.1%) between the two groups. The number of inadvertently resected PGs was significantly lower in the NIRAF group (18:6.9% vs. 36:12.8%; p = 0.021). Conclusions: These results suggest that NIRAF imaging may reduce temporary hypoparathyroidism and the risk of inadvertent resection of PGs in patients undergoing total thyroidectomy with CND.

Near-Infrared Autofluorescence in Atherosclerosis Associates With Ceroid and Is Generated by Oxidized Lipid-Induced Oxidative Stress.

[Figure: see text].

Intraoperative near-infrared autofluorescence imaging for hypocalcemia risk reduction after total thyroidectomy: Evidence from a meta-analysis.

This meta-analysis evaluates whether near-infrared autofluorescence (NIRAF) imaging reduces the risk of hypocalcemia after total thyroidectomy. A systematic literature search in PubMed, EMBASE, Web of Science, and Cochrane Library for studies from June 2011 to January 2021 comparing total thyroidectomy with NIRAF and conventional surgery (naked eye). Six eligible studies involving 2180 patients were included. The prevalence of transient hypocalcemia was 8.11% (40/493) and 25.19% (425/1687) in the NIRAF and naked eye groups (p < 0.0001), respectively. The prevalence of permanent hypocalcemia was 0% (0/493) and 2.19% (37/1687) in the NIRAF and naked eye groups (p=0.05), respectively. NIRAF reduces the risk of transient hypocalcemia and may possibly lower the rate of permanent hypocalcemia. Nonetheless, further studies are needed to verify our results and evaluate the cost-effectiveness of NIRAF in real-world clinical practice.

Evaluation of retinal pigment epithelium changes in serous pigment epithelial detachment in age-related macular degeneration

The purpose of this study was to quantitatively evaluate retinal pigment epithelium (RPE) changes in serous pigment epithelial detachment (PED) among patients with age-related macular degeneration by means of prototype multi-contrast optical coherence tomography (OCT), which is capable of simultaneous collection of OCT angiography, polarization-sensitive OCT, and standard OCT images. We evaluated 26 eyes of 21 patients with serous PED. RPE-melanin OCT images were calculated from the multi-contrast OCT dataset and compared with near-infrared autofluorescence images. An active RPE lesion was defined as an area of thickened RPE-melanin (≥ 70 μm; RPE70) on RPE-melanin OCT. Each PED area was divided into peak and slope regions. RPE70 area ratios were compared with the maximum PED height, PED area, PED volume, and slope area ratio (area of slope region/area of whole PED). RPE-melanin OCT images were consistent with near-infrared autofluorescence images. The RPE70 area ratio in the slope region was significantly negatively correlated with the slope area ratio. Development of active RPE lesions in the slope region was correlated with the PED configuration. Multi-contrast OCT is useful for objective evaluation of changes in the RPE in patients with age-related macular degeneration.

The effect of intraoperative autofluorescence monitoring on unintentional parathyroid gland excision rates and postoperative PTH concentrations-a single-blind randomized-controlled trial.

Intraoperative imaging of parathyroid glands (PGs) has been developed in order to reduce the risk of unintentional parathyroidectomy during total thyroidectomy. This novel modality is based on their intrinsic characteristic of autofluorescence (AF) after near-infrared light exposure. The aim of this study was to assess the effect of this method on the risk of unintentional PG excision (total or partial) during total thyroidectomy. This was a single-blind, randomized-controlled trial including adult patients who underwent scheduled total thyroidectomy between December 2019 and March 2020. These patients were randomly allocated to two groups: one in which near-infrared autofluorescence imaging (NIRAF) was applied (NIR group) and one without NIRAF (NONIR group). Hormonal and biochemical assessment was performed pre- and 24-h postoperatively. AF findings and the number of PGs autotransplanted were recorded. One-hundred and eighty patients were eligible. Unintentional (total or partial) PG excision rates during total thyroidectomy in the NONIR (n = 90) and NIR (n = 90) groups were 28.9% [95% confidence interval (CI) 19.8-39.4%] and 14.4% (95% CI 7.7-22.1%), respectively (p = 0.02). Furthermore, NIR reduced the risk of parathyroid tissue presence in the specimen sent for pathology (relative risk 0.51, 95% CI 0.28-0.92; p = 0.02). However, the number of PGs identified by NIR could not predict the risk of postoperative hypoparthyroidism. NIRAF imaging during total thyroidectomy led to a significant reduction in PG excision rates. However, this modality did not result in the reduction of postoperative hypoparathyroidism or hypocalcemia risk.

Autofluorescence pattern of parathyroid adenomas.

BackgroundPrimary hyperparathyroidism (pHPT) is a common endocrine pathology, and it is due to a single parathyroid adenoma in 80–85 per cent of patients. Near-infrared autofluorescence (NIRAF) has recently been used in endocrine surgery to help in the identification of parathyroid tissue, although there is currently no consensus on whether this technique can differentiate between normal and abnormal parathyroid glands. The aim of this study was to describe the autofluorescence pattern of parathyroid adenoma in pHPT.MethodsBetween January and June 2019, patients with pHPT who underwent surgical treatment for parathyroid adenoma were enrolled. Parathyroid autofluorescence was measured.ResultsTwenty-three patients with histologically confirmed parathyroid adenomas were included. Parathyroid adenomas showed a heterogeneous fluorescence pattern, and a well defined autofluorescent ‘cap’ region was observed in 17 of 23 specimens. This region was on average 28 per cent more fluorescent than the rest of the adenoma, and corresponded to a rim of normal histological parathyroid tissue (sensitivity and specificity 88 and 67 per cent respectively). After resection, all patients were treated successfully, with normal postoperative values of calcium and parathyroid hormone documented.ConclusionParathyroid adenomas show a heterogeneous autofluorescence pattern. Using NIRAF imaging, the majority of specimens showed a well defined autofluorescent portion corresponding to a rim of normal parathyroid tissue. Further studies should be conducted to validate these findings.

Central Serous Chorioretinopathy Analyzed by Multimodal Imaging.

PurposeWe correlated quantitative fundus autofluorescence (qAF) with other fundus features in patients exhibiting central serous chorioretinopathy (CSC).MethodsShort wavelength fundus autofluorescence (SW-AF, 488 nm excitation) was measured by qAF. Using nonnormalized images qAF values were calculated within eight concentric segments (qAF8) located at an eccentricity of 7° to 9°. Horizontal spectral domain optical coherence tomography (SD-OCT) scans and near-infrared fundus autofluorescence images (NIR-AF) were studied.ResultsThirty-six eyes of 20 patients (mean age 48.7± 8.5 years) diagnosed with CSC were studied. Thirteen patients had bilateral disease; four patients were female. In 22 eyes CSC was present in the macula; in one eye the lesion was in a peripapillary location, 10 involved both locations, and three were unaffected. Serous retinal detachment, retinal pigmented epithelial detachment (PED), outer retinal atrophy and subRPE hypertransmission were all features identifiable by SD-OCT. NIR-AF images were helpful in detecting foveal and parafoveal lesions. Sampling for retina-wide elevations in SW-AF intensity by measuring qAF8 did not indicate a generalizable relationship amongst CSC-diagnosed eyes. However, color-coded qAF images revealed alterations in SW-AF topography and intensity relative to healthy eyes at the same locations. Thus zones of higher than normal qAF intensity were found in association with SD-OCT detectable PED; loss of ellipsoid zone and interdigitation zone; and hyperreflectivity in outer retina. Pronounced decreases in qAF colocalized with serous retinal detachment and with outer retinal degeneration that included hypertransmission of SD-OCT signal into the choroid.ConclusionsLocalized elevations in qAF reflect increased bisretinoid in association with CSC lesions.Translational RelevanceFoci of elevated qAF at some stages of CSC contribute to the natural history of the disease.

Retinal Pigment Epithelium Atrophy in Recessive Stargardt Disease as Measured by Short-Wavelength and Near-Infrared Autofluorescence.

PurposeTo compare the detection of retinal pigment epithelium (RPE) atrophy in short-wavelength (SW-AF) and near-infrared autofluorescence (NIR-AF) images in Stargardt disease (STGD1) patients.MethodsSW-AF and NIR-AF images (115 eyes from 115 patients) were analyzed by two independent graders. Hypoautofluorescent (hypoAF) areas, indicative of RPE atrophy, were measured, and the two modalities were compared.ResultsPatients were segregated into four groups: nascent (6 [5%]), widespread (21 [18%]), discrete (55 [48%]), and chorioretinal atrophy (33 [29%]). The areas of hypoAF were larger in NIR-AF compared to SW-AF images in discrete (3.9 vs. 2.2 mm2, P < 0.001) and chorioretinal atrophy (12.7 vs. 11.4 mm2, P = 0.015). Similar findings were observed qualitatively in nascent and widespread atrophy patients. Using the area linear model (ALM), lesion area increased at similar rates in SW-AF and NIR-AF images of discrete atrophy (0.20 vs. 0.32 mm2/y, P = 0.275) and chorioretinal atrophy (1.30 vs. 1.74 mm2/y, P = 0.671). Using the radius linear model (RLM), the lesion effective radius also increased similarly in SW-AF and NIR-AF images in discrete (0.03 vs. 0.05 mm2/y, P = 0.221) and chorioretinal atrophy (0.08 vs. 0.10 mm2/y, P = 0.754) patients.ConclusionsNIR-AF reveals a larger area of RPE atrophy in STGD1 patients compared to SW-AF images, but rates of lesion enlargement in the two modalities are similar.Translational RelevanceMeasurements of RPE atrophy by AF imaging are crucial for monitoring STGD1 disease progression and given our findings we advocate greater use of NIR-AF for patients.

Laser Pointer: A Possible Risk for the Retina.

In recent years, an increasing incidence of laser pointer-associated retinal injuries has been observed, likely due to easy access to incorrectly classified laser pointers, their labelling as toys, and lack of awareness concerning the associated risk. Laser pointer exposure can lead to irreversible retinal damage and associated vision loss, depending on the wavelength, radiation power, duration of exposure, localization, and spot size. Pronounced retinal laser damage is especially seen in children and teenagers. The structural appearance of retinal laser pointer damage varies and, in some cases, may be a diagnostic challenge. Besides often subtle findings on optical coherence tomography examination, characteristic alterations on near-infrared autofluorescence imaging may be valuable for the diagnosis of retinal laser pointer injuries and for differentiating other retinal lesions with similar appearance. The increase in laser pointer injuries indicates that regulatory actions and increased public awareness are required regarding the dangers of laser pointers.

Intravascular Photoacoustic and Autofluorescence Imaging for Detecting Intraplaque Hemorrhage: A Feasibility Study

Intraplaque hemorrhage (IPH), which is a trigger and conveys all blood components into the plaque, influencing the cholesterol crystal formation and retention, haemoglobin and oxidative enzymes, and blood-borne proteolytic activity. IPH is one of the key determinants for plaque vulnerability. In this paper, we proposed a dual-modality endoscope probe with a diameter of 1 mm for simultaneously detecting the lipid core and IPH, our system was composed of photoacoustic imaging (PAI) and near-infrared auto-fluorescence imaging (NIRAFI). The lipid as endogenous marker of intravascular PAI could visualize the lipid distribution of atherosclerotic plaque, and bilirubin as the marker of intravascular NIRAFI was used to locate and quantify the IPH. The phantom and ex vivo rabbit aorta experiments had proved the feasibility and capability of the dual-mode probe for imaging IPH and lipid core expansion. And the results indicated that the dual-mode intravascular endoscope had the potential for accurately detecting IPH in atherosclerotic plaques.

Clinical Application of Near-infrared Autofluorescence Detection of Parathyroid Glands in Thyroid Surgery

The purpose of this paper is to compare and analyze the advantages and disadvantages of near-infrared autofluorescence (NIRAF) imaging, nano-carbon negative imaging and conventional naked eye recognition technology in recognizing parathyroid glands during surgery, and to preliminary evaluate the effectiveness, safety and feasibility of NIRAF imaging in the recognition of parathyroid glands. The clinical trials retrospectively analyzed 36 patients, including 12 patients in Group A (NIRAF imaging group), 12 patients in Group B (nano-carbon negative imaging group), and 12 patients in Group C (conventional naked eye recognition group). The number of parathyroid glands recognized during surgery in Group A was more than that in Group B and C. The time taken to recognize parathyroid glands in Group A was shorter than that in Group B and C. There was no significant difference in the average calcium ion levels of the three groups A, B and C before surgery. After surgery, the average calcium ion level of Group A was not significantly different from that of Group B, but it was higher than that of Group C, and the difference was significant. The incidence of postoperative hypocalcemia in Group A was not significantly different from that in Group B, but it was lower than that in Group C. The incidence of postoperative symptomatic hypocalcemia in Group A was lower than that in Group B and C. Compared with traditional technology, NIRAF can recognize more parathyroid glands during surgery, take less time, and make the probability of postoperative hypocalcemia and symptomatic hypocalcemia lower during thyroid surgery. It needs noninvasive and simple operation. It is a kind of safe, effective and feasible parathyroid gland recognition technology, which is worth further exploration.

Spectral-Domain Optical Coherence Tomography Is More Sensitive for Hydroxychloroquine-Related Structural Abnormalities Than Short-Wavelength and Near-Infrared Autofluorescence.

PurposeTo analyze the appearance of structural abnormalities due to hydroxychloroquine (HCQ) toxicity by spectral-domain optical coherence tomography (SD-OCT) and short-wavelength autofluorescence (SW-AF) and near-infrared fundus autofluorescence (NIR-AF) imaging.MethodsThis retrospective cohort study included 88 eyes from 44 patients who had a history of or were currently taking HCQ. SD-OCT, SW-AF, and NIR-AF images were analyzed by two independent graders for the detection of HCQ-associated abnormalities.ResultsSixty eyes (30 patients, 68%) presented with no abnormalities for either imaging modality. Twenty eyes (10 patients, 23%) presented with parafoveal abnormalities (ellipsoid zone attenuation and/or interdigitation zone continuity loss) in SD-OCT scans but with qualitatively normal SW-AF and NIR-AF images. Eight eyes (four patients, 9%) presented with bull's-eye maculopathy in SW-AF and NIR-AF images, with corresponding outer retinal structures disrupted parafoveally in SD-OCT scans (“flying saucer” sign). No patients presented with normal SD-OCT scans and concurrent abnormalities in SW-AF or NIR-AF images.ConclusionsSD-OCT was more sensitive in detecting structural abnormalities than either SW-AF or NIR-AF imaging, suggesting its superiority as a screening imaging modality for HCQ toxicity. Maculopathy and abnormalities in the retinal pigment epithelium from HCQ toxicity can be appreciated in both SW-AF and NIR-AF images.Translational RelevanceAlthough debate exists regarding the best imaging modalities for screening patients for potential HCQ toxicity, our study supports the use of SD-OCT over both SW-AF and NIR-AF imaging as a screening modality.

Short-Wavelength and Near-Infrared Autofluorescence in Patients with Deficiencies of the Visual Cycle and Phototransduction

Fundus autofluorescence is a valuable imaging tool in the diagnosis of inherited retinal dystrophies. With the advent of gene therapy and the numerous ongoing clinical trials for inherited retinal degenerations, quantifiable and reliable outcome measurements continually need to be identified. In this retrospective analysis, normalized and non-normalized short-wavelength (SW-AF) and near-infrared (NIR-AF) autofluorescence images of ten patients with mutations in visual cycle (VC) genes and nineteen patients with mutations in phototransduction (PT) genes were analyzed. Normalized SW-AF and NIR-AF images appeared darker in all patients with mutations in the VC as compared to patients with mutations in PT despite the use of significantly higher detector settings for image acquisition in the former group. These findings were corroborated by quantitative analysis of non-normalized SW-AF and NIR-AF images; signal intensities were significantly lower in all patients with mutations in VC genes as compared to those with mutations in PT genes. We conclude that qualitative and quantitative SW-AF and NIR-AF images can serve as biomarkers of deficiencies specific to the VC. Additionally, quantitative autofluorescence may have potential for use as an outcome measurement to detect VC activity in conjunction with future therapies for patients with mutations in the VC.