Shaving Papillary Thyroid Carcinoma Involving Functioning Recurrent Laryngeal Nerve: Safety of Incomplete Tumor Resection and Nerve Sparing.

BACKGROUND: Whether to sacrifice or spare the recurrent laryngeal nerve (RLN) when papillary thyroid carcinoma (PTC) involves a functioning RLN remains controversial. Oncological outcomes after shaving PTC with gross remnant on the RLN have been rarely reported. The objective of this study was to evaluate the oncological outcomes of patients who underwent shaving of a PTC from the RLN, leaving a gross residual tumor with the intent of vocal function preservation. METHODS: A retrospective, cohort study was conducted in 47 patients who were determined to have PTC invasion of the RLN via intraoperative inspection and underwent tumor shaving with macroscopic remnant (R2 resection) less than 1 cm in length and 4 mm in thickness. Median follow-up period was 93 (range, 60-215) months. The primary endpoint was the recurrence-free survival and the progression-free survival. Secondary endpoints were biochemical outcomes (serum thyroglobulin) and vocal cord function. RESULTS: Of the 47 patients, five (10.6%) patients showed recurrence (central neck, 3; lateral neck, 2) without death or distant metastasis. The RLN was resected along with the tumor in one (2.1%) patient who presented with progression of the residual tumor. Postoperative temporary vocal cord paralysis occurred in six (12.8%) patients without permanent cases. The final nonstimulated serum thyroglobulin was 0.7 ± 1.8 ng/ml. CONCLUSIONS: Shaving a tumor from a RLN with gross residual disease may be considered an alternative strategy to preserve vocal function when complete tumor resection with nerve preservation is impossible in patients with PTC invading a functioning RLN.

Application of Adhesive Skin Electrode for Intraoperative Neuromonitoring During Enucleation of a Cervical Vagal Schwannoma.

BACKGROUND: No reports on applying adhesive skin electrodes for intraoperative nerve monitoring (IONM) of the vagus nerve during schwannoma enucleation have been reported in the literature. METHODS: A 45-year-old patient was referred to our institution with a 2.2 cm mass in the left lateral neck, suspected to be a vagal nerve schwannoma. A pair of surface electrodes were attached to the lateral margin of the thyroid cartilage. After exposing the tumor, the authors selected the incision site avoiding the expected course of the vagus nerve fibers after mapping on the surface of the tumor. RESULTS: Postoperative vocal cord function was intact, without aspiration or dysphagia. CONCLUSIONS: The authors report the successful use of skin electrodes for IONM of the vagus nerve during cervical vagal schwannoma removal, suggesting the feasibility of applying these electrodes for IONM of neck surgeries other than those associated with the thyroid or parathyroid glands.

Five-year follow-up results of thermal ablation for low-risk papillary thyroid microcarcinomas: systematic review and meta-analysis.

OBJECTIVES: Confidence in long-term treatment results of thermal ablation for papillary thyroid microcarcinoma (PTMC) is required in comparison with active surveillance. The objective of this meta-analysis is to report 5-year follow-up results of thermal ablation for PTMC. METHODS: Ovid MEDLINE and EMBASE databases were searched through May 30, 2020, for studies reporting outcomes in patients with PTMC treated with thermal ablation and followed up for at least 5 years. Data were extracted and methodological quality was assessed independently by two radiologists according to the PRISMA guidelines. RESULTS: Three studies, involving 207 patients with 219 PTMCs, met the inclusion criteria through database searches. None of these patients experienced local tumor recurrence, lymph node metastasis, or distant metastasis or underwent delayed surgery during a mean pooled 67.8-month follow-up. Five new tumors appeared in the remaining thyroid gland of four patients, with four of these tumors successfully treated by repeat thermal ablation. The pooled mean major complication rate was 1.2%, with no patient experiencing life-threatening or delayed complications. CONCLUSIONS: Thermal ablation is an excellent local tumor control method in patients with low-risk PTMC, with low major complication rates at 5 years. KEY POINTS: • No local tumor recurrence, lymph node metastasis, or distant metastasis was noted by thermal ablation during follow-up of 5 years and none underwent delayed surgery. • The pooled mean major complication rate was 1.2%.

Intraoperative Neuromonitoring of Recurrent Laryngeal Nerve During Thyroidectomy with Adhesive Skin Electrodes.

BACKGROUND: Alternative methods to overcome limitations of electromyogram (EMG) tube applied for intraoperative neuromonitoring (IONM) of recurrent laryngeal nerve (RLN) during thyroidectomy have been introduced. In this study, we evaluated the feasibility of adhesive skin electrodes for IONM of RLN in patients who underwent thyroidectomy. METHODS: A total of 39 nerves at risk were prospectively enrolled in this study. Twenty-five patients with papillary thyroid carcinoma, 3 patients with follicular neoplasm, and 2 patients with Graves' disease underwent thyroidectomy. All patients were intubated with EMG tube, and two disposable pre-gelled surface electrodes were attached to skin at both upper margins of thyroid cartilage. We followed the standard procedure of IONM, and the latency (msec) and amplitude (µV) of each signal were recorded prospectively. RESULTS: Intraoperative neuromonitoring using skin adhesive electrodes was successful in all nerves at risk. Amplitudes of the signals in IONM were significantly lower compared to those from EMG tube at each step of IONM, while no significant difference was identified in latency between two methods. Four nerves at risk (10.3%) showed loss of signal (<100 µV) during the steps of IONM from EMG tube, while all nerves at risk from adhesive skin electrodes showed acceptable biphasic EMG signal. CONCLUSION: We verified the usefulness of adhesive skin electrodes for IONM of RLN during thyroidectomy. Although lower amplitude remains the major limitation of this technique, adhesive skin electrodes may be considered an alternative method for IONM during thyroidectomy.

Rabbit model of tracheal stenosis using cylindrical diffuser.

BACKGROUND AND OBJECTIVE: Variable methods of animal model have been introduced to develop tracheal stenosis. However, none of the prior models allow for predictable determination of the grade of stenosis. This study sought to establish an animal model of tracheal stenosis by using a cylindrical diffuser and to evaluate the feasibility of a reproducible model. STUDY DESIGN/MATERIALS AND METHODS: A cylindrical diffuser was developed to have a 5 mm active segment to emit laser light circumferentially. Twenty one New Zealand white rabbits were enrolled in this study. The cylindrical diffuser was inserted transorally under bronchoscopic view and the diffused light was delivered to tracheal mucosa 2 cm below the level of vocal cord. Input power of irradiation was 10 W, 5 seconds in group A (n = 7), 10 W, 7 seconds in group B (n = 7), and 8 W, 5 seconds in group C (n = 7). The degree of tracheal stenosis was observed weekly and the rabbits were euthanized 4 weeks after the laser irradiation. RESULTS: The degree of stenosis in group B (90-98%) was significantly larger than that of group A (75-92%) (P = 0.004), while degree in group C (24-35%) was significantly smaller than that of group A (P < 0.001). Two rabbits of group A were euthanized at 3 weeks due to costal retraction. In group B, six rabbits died within 3 weeks after laser irradiation due to severe tracheal stenosis and tracheal malacia, while one rabbit was euthanized 16 days after the irradiation. All rabbits in group C survived up to 4 weeks. Survival between three groups showed significant difference (P = 0.001). CONCLUSION: The degree of stenosis was significantly different according to the delivered optical energy to tracheal mucosa. Therefore, the proposed model may be used in animal studies to emulate variable grades of tracheal stenosis. Lasers Surg. Med. 49:372-379, 2017. © 2016 Wiley Periodicals, Inc.

MAGE-A1-6 expression in patients with head and neck squamous cell carcinoma: impact on clinical patterns and oncologic outcomes.

BACKGROUND: Various subtypes of melanoma-associated antigens (MAGEs) are expressed in the tumor tissues of patients with head and neck squamous cell carcinoma (HNSCC). However, little data are currently available on how the gene expression of MAGEs impacts clinical patterns and oncologic outcomes. We have therefore evaluated the expression of MAGE-A1-6 (A1-6) subtypes in tumor tissues of patients with HNSCC and the clinical impact of this expression. METHODS: This was a retrospective review of 53 patients with histologically proven HNSCC of the oral cavity, oropharynx, larynx, or hypopharynx who underwent both treatment and analysis by reverse transcription (RT)-PCR assay with a common primer to identify the expression of MAGE-A1-6 subtypes in the tumor tissue. The clinicopathologic factors and oncologic outcomes of these patients and the correlations of both to MAGE-A1-6 gene expression were analyzed. RESULTS: MAGE-A1-6 subtypes were expressed in the tumor tissues of 37 patients (69.8 %). Patient age of ≥65 years [p = 0.031, hazard ratio (HR) 4.866] and advanced American Joint Committee on Cancer stage (p = 0.035, HR 4.291) were independent risk factors for expression of MAGE-A1-6 subtypes. Patients with MAGE-A1-6 expression had lower disease-free survival (p = 0.029), disease-specific survival (p = 0.070), and overall survival (p = 0.017) rates. Overall survival rate was independently associated to chemotherapy (p = 0.011, HR 2.859), while no surgery (p = 0.050, HR 2.400) and MAGE-A1-6 expression (p = 0.050, HR 2.527) showed borderline significance. CONCLUSION: In our patient group the expression of MAGE-A1-6 subtypes in tumor tissues of patients with HNSCC was correlated with advanced clinical stage of cancer and poor oncologic outcomes. We suggest that gene expression of MAGE-A1-6 subtypes may be considered to be a predictive factor to determine patient treatment or follow-up strategy.

Preliminary study of optical coherence tomography imaging to identify microscopic extrathyroidal extension in patients with papillary thyroid carcinoma.

BACKGROUND AND OBJECTIVES: We evaluated the feasibility of using optical coherence tomography (OCT), to identify microscopic extrathyroidal extension (mETE) in ex vivo thyroidectomy specimens of patients who underwent thyroidectomy for the treatment of papillary thyroid carcinoma (PTC). METHODS: A total of 170 ex vivo OCT images of the tumor, were acquired just after completion of thyroidectomy in 17 patients. The OCT images of each patient were separately evaluated by two blinded investigators, and the outcomes were compared with the histopathology reports. RESULTS: The sensitivity and specificity of mETE identification from the OCT images were 81.4% and 86.0%, respectively, for the first investigator, and 82.9% and 87.0%, respectively, for the second investigator. Substantial agreement between the investigators was verified by Cohen's κ (Cohen's κ = 0.772). CONCLUSION: In this preliminary study of a limited series of ex vivo thyroidectomy specimens, we verified the feasibility of OCT as a method of identifying mETE in patients with PTC.

Pathologic features of metastatic lymph nodes identified from prophylactic central neck dissection in patients with papillary thyroid carcinoma.

The importance of pathologic features of metastatic lymph nodes (LNs), such as size, number, and extranodal extension, has been recently emphasized in patients with papillary thyroid carcinoma (PTC). We evaluated the characteristics of metastatic LNs identified after prophylactic central neck dissection (CND) in patients with PTC. We performed a retrospective review of 1,046 patients who underwent unilateral or bilateral thyroidectomy with ipsilateral prophylactic CND. We reviewed the characteristics of the metastatic LNs and analyzed their correlation to the clinicopathologic characteristics of the primary tumor. Cervical LN metastasis after prophylactic CND was identified in 280 out of 1046 patients (26.8 %). The size of metastatic foci (≥2 mm) was independently correlated with primary tumor size (≥1 cm) (p = 0.016, OR = 1.88). Primary tumor size (≥1 cm) was also correlated to the number of metastatic LNs (≥5) (p = 0.004, OR = 3.14) and extranodal extension (p = 0.021, OR = 2.41) in univariate analysis. The size of the primary tumor affects pathologic features of subclinical LN metastasis in patients with PTC. Patients with primary tumors ≥1 cm have an increased risk of larger LN metastases (≥2 mm), an increased number of LN metastases (≥5), and a higher incidence of ENE, which should be considered in decision for prophylactic CND.

Correlation of minimal extrathyroidal extension with pathologic features of lymph node metastasis in patients with papillary thyroid carcinoma.

BACKGROUND: The impact of minimal extrathyroidal extension (mETE) to the prognosis of patients with papillary thyroid carcinoma (PTC) is controversial. In this study, we investigated whether mETE is related to the aggressive biology of metastatic lymph node (LN) in patients with PTC. METHODS: A retrospective review of 369 patients who had biopsy-confirmed cervical LN metastasis after initial surgery for PTC was conducted. The correlations of mETE with the specific features of metastatic LNs such as the LN size, number, LN ratio, and presence of extranodal extension (ENE) were statistically analyzed. RESULTS: Size of the primary tumor (≥1 cm) had independent correlations to mETE (HR = 5.750). While mETE was related to number of metastatic LNs (≥5), LN ratio (≥0.31) and ENE in univariate analysis, only ENE (HR = 2.322) was independently correlated to mETE in our series. Along with mETE, size of primary tumor (≥1 cm) had significant impact on ENE (HR = 2.107). CONCLUSION: Minimal ETE particularly those with larger primary tumor (≥1 cm) may be still considered as a significant factor regarding the management of cervical LNs in patients with PTC.

Papillary thyroid carcinoma with exclusive involvement of a functioning recurrent laryngeal nerve may be treated with shaving technique.

OBJECTIVES: We sought to validate the feasibility of preserving a functioning recurrent laryngeal nerve (RLN) invaded by papillary thyroid carcinoma (PTC) using a shaving technique followed by high-dose radioactive iodine (RAI) therapy. METHODS: A retrospective review of 34 patients with locally invasive PTC who had exclusive tumor involvement of a functioning RLN was performed. All patients underwent total thyroidectomy and high-dose RAI therapy. A shaving technique was conducted with the goal of leaving the smallest amount of residual tumor as possible while attempting to preserve nerve function. Clinicopathologic factors and oncologic outcomes of the patients with resected RLN (group A, n = 14) and preserved RLN (group B, n = 20) were compared. RESULTS: The two groups showed no differences in clinicopathologic factors or follow-up period. Mean dose of radioiodine therapy was 245.0 ± 140.3 mCi (range 100-540 mCi). Permanent postoperative vocal cord paralysis after RLN shaving occurred in two patients of group B (10%). Only one patient (5%) in group B had local recurrence at the thyroid bed where the residual tumor was located. The overall recurrence rate was 35.7% (5/14) and 20.0% (4/20) in groups A and B, respectively showing no significant difference (p = 0.525). There were no cases of death due to PTC during the median follow-up of 75 months (range 36-159 months). CONCLUSIONS: Patients with locally invasive PTC with exclusive involvement of a functioning RLN may be treated by nerve shaving followed by treatment of the macroscopic residual tumor with high-dose RAI therapy.

Multimodal imaging using optical coherence tomography and endolaryngeal ultrasonography in a new rabbit VX2 laryngeal cancer model.

BACKGROUND AND OBJECTIVE: Optical coherence tomography (OCT) provides ultrahigh-resolution imaging of tissues within a depth of a few millimeters, whereas ultrasonography provides good imaging further below the surface. We aimed to develop a minimally invasive rabbit model of VX2 laryngeal cancer, suitable for these two imaging modalities through a transoral approach. We also sought to study the utility of combined OCT and endolaryngeal ultrasonography (EUS) for evaluation of early and advanced laryngeal cancer, using this model. MATERIALS AND METHODS: VX2 tumor suspension was inoculated into the vocal folds of ten rabbits by injection through the trans-thyrohyoid membrane. The tumor model was characterized by rigid laryngoscopy and the tumor generation rate was 80% (8/10). Correlation between frequency-domain OCT and high-frequency EUS were used to visualize laryngeal tumors in the area of protruding mass formation in four rabbits, one week after injection (group A) and the remaining four rabbits two weeks after injection (group B). RESULTS: A small submucosal tumor was observed with rigid laryngoscopy in group A, and pathologic evaluation showed that the tumor was close to the basement membrane of the vocal fold mucosa, but had not invaded. OCT confirmed that the lining of the mucosa and basement membrane of the vocal fold was not broken, but the mucosa had thinned at the most elevated ridge. However, these lesions were not detected by EUS, and the overall shape of the tumor could not be clearly identified by EUS. A large tumor filling the laryngeal lumen was observed with rigid laryngoscopy in group B, and nearly the entire vocal fold, including the paraglottic space, was found to be involved on pathologic analysis. Distinguishing between normal structures and tumor was difficult using OCT; however, EUS confirmed the overall shape, size, and extent of the tumor, and the paraglottic space and thyroid cartilage were shown to be intact. CONCLUSIONS: This study is the first experimental trial, assessing the value of multimodal imaging using OCT and EUS in a rabbit VX2 laryngeal tumor model. Combining OCT and EUS helped to identify changes in laryngeal mucous membranes, and could potentially be used to identify laryngeal tumors and predict how tumors progress. This combined modality could help in determining tumor extent, assisting in diagnosis, and establishing a treatment plan for laryngeal cancer.

Target delivery and cell imaging using hyaluronic acid-functionalized graphene quantum dots.

This work demonstrates the way to achieve efficient and target specific delivery of a graphene quantum dot (GQD) using hyaluronic acid (HA) (GQD-HA) as a targeting agent. HA has been anchored to a GQD that accepts the fascinating adhesive properties of the catechol moiety, dopamine hydrochloride, conjugated to HA, which was confirmed by X-ray photoelectron spectroscopy. Transmission electron microscopy revealed a particle size of ∼20 nm, and the fluorescence spectra revealed significant fluorescence intensity even after the anchoring of HA. The prepared GQD-HA was applied to CD44 receptor overexpressed tumor-bearing balb/c female mice, and the in vivo biodistribution investigation demonstrated more bright fluorescence from the tumor tissue. In vitro cellular imaging, via a confocal laser scanning microscope, exhibited strong fluorescence from CD44 overexpressed A549 cells. Both in vivo and in vitro results showed the effectiveness of using HA as targeting molecule. The loading and release kinetics of the hydrophobic drug doxorubicin from a GQD under mildly acidic conditions showed that a GQD can be considered as a novel drug carrier, while the nontoxic behavior from the MTT assay strongly supports the identification of GQD-HA as a biocompatible material.

The relationship between the BRAF(V600E) mutation in papillary thyroid microcarcinoma and clinicopathologic factors.

BACKGROUND: The BRAF(V600E) mutation, which accounts for about 60-80% papillary thyroid carcinoma(PTC), has been identifiedas a prognostic marker for risk stratification of PTC patients. However, the BRAF(V600E) mutation as a prognostic marker in papillary thyroid microcarcinoma (PTMC) is unclear. METHODS: We performed a retrospective review of 101 patients who underwent surgery for PTMC. We studied the prevalence of the BRAF(V600E) mutation. The associations between the BRAF(V600E) mutation and clinicopathologic characteristics were analyzed. RESULTS: The BRAF(V600E) mutation was observed in 72 patients (71.3%). There was no statistically significant correlation in age, gender, multifocality, extrathyroidal extension, presence of Hashimoto thyroiditis, and lymph node metastasis between the BRAF(V600E) mutant group and wild group. CONCLUSIONS: The BRAF(V600E) mutation is not significantly associated with prognostic factors in PTMC.

Salvage transoral laser supraglottic laryngectomy after radiation failure: a report of seven cases.

OBJECTIVES: We evaluated the oncological and functional outcomes of salvage transoral laser supraglottic laryngectomy after radiation failure. In addition, we demonstrated the usefulness of laser surgery in patients with recurrent supraglottic cancer. METHODS: Between December 1999 and May 2011,7 patients (6 men and 1 woman) underwent transoral laser supraglottic laryngectomy after radiation failure. We conducted 4 different types of endoscopic supraglottic laryngectomy. In the cases with lymph node metastasis, we performed neck dissection at the time of laser surgery. RESULTS: All patients had recurrent squamous cell carcinoma confirmed on the surgical specimen. Two patients were classified as having T1 disease, 2 as having T2 disease, and 3 as having T3 disease with preepiglottic space involvement. The 2- and 5-year overall survival rates were 85.7% and 68.6%, respectively. There was a recurrence at 8 months of followup after laser surgery in 1 patient; he underwent successful salvage total laryngectomy. The ultimate local control rate was 100%, and the laryngeal preservation rate was 85.7%. The hospitalization times ranged from 2 to 32 days (mean, 15.6 days). The mean decannulation time was 10.7 days (range, 5 to 30 days). All patients started oral feeding within 1 to 3 days after surgery. CONCLUSIONS: Salvage transoral laser supraglottic laryngectomy following radiation failure seems a feasible and oncologically safe procedure in recurrent supraglottic cancers ranging from T1 to selected T3 with minimal preepiglottic space involvement. It can be an option for minimally invasive organ preservation surgery with lesser morbidity for recurrent supraglottic cancer.

Clinical characteristics of papillary thyroid microcarcinoma less than or equal to 5 mm on ultrasonography.

Management of papillary thyroid microcarcinoma sized ≤5 mm identified on ultrasonography is controversial. In this study, we evaluated the clinical characteristics of papillary thyroid microcarcinoma sized ≤5 mm on ultrasonography in comparison to those >5 mm and sought to present rationales for optimal management in papillary thyroid microcarcinoma ≤5 mm. The medical records of 396 patients who underwent surgery for papillary thyroid carcinoma between 2009 and 2011 were retrospectively analyzed. The patients were grouped into A (≤5 mm, n = 132) or B (>5 mm, n = 264) and the clinicopathologic characteristics of the patients were reviewed and compared between the two groups. Tumor capsular invasion (45.5 vs. 59.8 %, p = 0.007) and cervical lymph node metastasis (18.2 vs. 29.2 %, p = 0.018) were more frequent in group B. Nonetheless, group A presented lymph node metastasis in 42.3 % of multifocal cases showing no difference to that of group B (41.5 %, p = 0.946) and also included five cases (3.8 %) of lateral neck metastasis. Multifocality was the only predictive factor for lymph node metastasis in group A (p < 0.001). Over half (55.3 %) of the patients of group A were diagnosed with papillary carcinoma in private clinics; however, only 5.5 % of these patients underwent assessment of lateral neck lymph nodes initially. In conclusion, higher risk of cervical lymph node metastasis should be considered in evaluation and surgical decision of papillary thyroid microcarcinoma ≤5 mm identified on ultrasonography with multifocality. Evaluation of the cervical lymph nodes including the lateral neck should not be overlooked when suspicious thyroid nodule suggesting malignancy sized ≤5 mm shows multifocal lesions.

Partial cutting of sternothyroid muscle during total thyroidectomy: impact on postoperative vocal outcomes.

BACKGROUND: Cutting the sternothyroid (ST) muscle is a useful technique to expose the superior pole of thyroid gland during thyroidectomy. In this study, we evaluated the impact of partial cutting of the ST muscle on postoperative vocal outcomes after total thyroidectomy. METHODS: A retrospective review of 57 patients who underwent total thyroidectomy with central neck dissection for micropapillary thyroid carcinoma was conducted. Group A (n = 26) included those without cutting the ST muscle, while group B (n = 31) included patients whose muscle was partially cut at the superior pole. All patients underwent voice analysis before the operation and 2 weeks and 1 month after the surgery, and the outcomes were compared between the two groups. RESULTS: There were no differences between the two groups regarding the outcomes at each time of voice analysis. Group A showed a decrease of maximum frequency 2 weeks after surgery but showed no difference after 1 month. Group B showed a mild decrease in maximum frequency 2 weeks after surgery, but the difference was not significant. CONCLUSION: Partial cutting of ST muscle during thyroidectomy is useful to expose the superior pole without significant negative impact on postoperative outcomes of vocal analysis.

Detectable depth of unexposed parathyroid glands using near-infrared autofluorescence imaging in thyroid surgery.

Background: Near-infrared light can penetrate the fat or connective tissues overlying the parathyroid gland (PG), enabling early localization of the PG by near-infrared autofluorescence (NIRAF) imaging. However, the depth at which the PG can be detected has not been reported. In this study, we investigated the detectable depth of unexposed PGs using NIRAF during thyroidectomy. Materials and methods: Fifty-one unexposed PGs from 30 consecutive thyroidectomy patients, mapped by an experienced surgeon (K.D. Lee) with the use of NIRAF imaging, were included. For NIRAF detection of PGs, a lab-built camera imaging system was used. Detectable depths of the unexposed PGs were measured using a Vernier caliper. The NIRAF images were classified as faint or bright depending on whether a novice could successfully interpret the image as showing the PG. Data on variables that may affect detectable depth and NIRAF intensity were collected. Results: Detectable depth ranged between 0.35 and 3.05 mm, with a mean of 1.23 ± 0.73 mm. The average NIRAF intensity of unexposed PGs was 3.13 au. After dissection of the overlying tissue, the intensity of the exposed PG increased to 4.88 au (p < 0.001). No difference in NIRAF intensity between fat-covered (3.27 ± 0.90 au) and connective tissue-covered PGs (3.00 ± 1.23 au) was observed (p = 0.369). PGs covered by fat tissue (depth: 1.77 ± 0.67 mm) were found at deeper locations than those covered by connective tissue (depth: 0.70 ± 0.21 mm) (p < 0.001). The brightness of images of the faint group (2.14 ± 0.48 au) was on average 1.24 au lower than that of the bright group (3.38 ± 1.04 au) (p = 0.001). A novice successfully localized 80.4% of the unexposed PGs. Other variables did not significantly affect detectable depth. Conclusion: Unexposed PGs could be mapped using NIRAF imaging at a maximum depth of 3.05 mm and an average depth of 1.23 mm. A novice was able to localize the PGs before they were visible to the naked eye at a high rate. These results can be used as reference data for localization of unexposed PGs in thyroid surgery.

Emerging Imaging Technologies for Parathyroid Gland Identification and Vascular Assessment in Thyroid Surgery: A Review From the American Head and Neck Society Endocrine Surgery Section.

Importance: Identification and preservation of parathyroid glands (PGs) remain challenging despite advances in surgical techniques. Considerable morbidity and even mortality result from hypoparathyroidism caused by devascularization or inadvertent removal of PGs. Emerging imaging technologies hold promise to improve identification and preservation of PGs during thyroid surgery. Observation: This narrative review (1) comprehensively reviews PG identification and vascular assessment using near-infrared autofluorescence (NIRAF)-both label free and in combination with indocyanine green-based on a comprehensive literature review and (2) offers a manual for possible implementation these emerging technologies in thyroid surgery. Conclusions and Relevance: Emerging technologies hold promise to improve PG identification and preservation during thyroidectomy. Future research should address variables affecting the degree of fluorescence in NIRAF, standardization of signal quantification, definitions and standardization of parameters of indocyanine green injection that correlate with postoperative PG function, the financial effect of these emerging technologies on near-term and longer-term costs, the adoption learning curve and effect on surgical training, and long-term outcomes of key quality metrics in adequately powered randomized clinical trials evaluating PG preservation.