Intraoperative Identification Of Parathyroid Glands Research Articles

Artificial Intelligence for Intraoperative Guidance: Using an Object Detection Model in Conjunction With Data Augmentation to Detect Parathyroid Glands During Thyroidectomy

Background: Postoperative hypoparathyroidism is a major complication of thyroidectomy that occurs when the parathyroid glands are inadvertently damaged during surgery. Although intraoperative images are rarely used to train AI because of its complex nature, our group recognized the potential of training AI to intraoperatively detect parathyroid glands using various augmentation methods. The aim of the present study was to train an effective artificial intelligence (AI) model to detect parathyroid glands during thyroidectomy and evaluate its accuracy. Methods: Video clips of the parathyroid gland were collected during thyroid lobectomy procedures. Confirmed parathyroid images were used to form three types of datasets according to augmentation status: baseline, geometric transformation, and generative adversarial network-based image inpainting. The average precision was set as the primary outcome regarding the performance of parathyroid detection performance. Findings: The performance of the AI model in detecting parathyroid glands based on baseline data was 77%. This performance was enhanced by applying both geometric transformation and image inpainting augmentation methods. Between the two, the geometric transformation data augmentation dataset demonstrated superior results compared to that of the image inpainting model. The average precision was 79% in the transformation dataset vs. 78.6% in the inpainting dataset. However, when the model was subjected to images of a completely different thyroidectomy approach, image inpainting methods proved to be more effective compared to both geometric transformation and baseline (46% vs. 37% vs. 33%). Conclusions: Our study demonstrated the utility of our AI model, which, when aided with appropriate augmentation methods, is potentially an effective and generalizable tool for intraoperative identification of parathyroid glands during thyroidectomy. Furthermore, this technology has significant potential to be easily extended to identifying important structures during other surgical procedures in general. Funding Information: Basic Science Research Program of the National Research Foundation of Korea [NRF-2019R1C1C1008384]. Declaration of Interests: We declare no competing interests. Ethics Approval Statement: Institutional review board approval was acquired (GDIRB2019-359), and research was conducted in accordance with the Declaration of Helsinki in its latest form.

Intraoperative identification of parathyroid glands by autofluorescence on total thyroidectomy – Does it really reduces post-operative hypocalcemia?

Abstract Background Intraoperative identification of parathyroid glands which remains largely dependent on the surgeon's expertise, is a major challenge in endocrine surgery and the most efficient way to reduce postoperative hypocalcemia and its important morbidity. Since the description on autofluorescence of parathyroid glands by Paras et al. in 2011, other works had confirmed the utility of this property in the identification of the glands but its efficacy in reducing hypocalcemia is not completely stated. In this study we evaluate the utilization of a low-cost device in total thyroidectomy. Methods In a before and after controlled study we compared patients submitted to total thyroidectomy by the same surgeon in two periods: From January 2017 to February 2018 (visual identification of parathyroid glands) and from February 2018 to December 2019 (with utilization of the near infrared system). Main outcomes included postoperative hypocalcemia and hypoparathyroidism, parathyroid identification and incidental resection. Results Patients in the study group displayed significantly lower postoperative hypoparathyroidism (p = 0.044). In spite of the reduction observed in study group absolute values of calcium and number of hypocalcemic patients didn't achieve statistical significance. There were no patients with permanent hypocalcemia in study group comparing with 3 in the control group. Number of parathyroid glands identified was significantly higher in study group (p Near infrared autofluorescence device was able to identify accurately inadvertently removed parathyroid glands, with a sensivity of 100% and a specificity of 87.5%. Conclusions Event though we couldn't demonstrate significant improvement in transient postoperative hypocalcemia, the reduction of permanent hypocalcemia and the improvement in surgeon's ability and confidence in the identification of parathyroid glands could make near infrared autofluorescence an useful tool in surgery of thyroid gland.

Factors affecting the near-infrared autofluorescence intensity of parathyroid glands and intraoperative identification of parathyroid glands

Objective: To evaluate the potential factors influencing the parathyroid autofluorescence intensity of near-infrared fluorescent (NIRF) and further value of NIRF in identifying the parathyroid during surgery. Methods: The clinical data of 51 patients who underwent thyroid or parathyroid surgery in the Department of Thyroid Surgery, the First Affiliated Hospital of Zhengzhou University from April to June 2019 were retrospectively analyzed, including 16 males and 35 females, aged 18 to 74 years.The fluorescence intensity (FI) of the parathyroid glands, thyroid glands and background, and the number of parathyroid glands detected by NIRF and white light were measured. Variance analysis, two independent samples t test and Spearman rank correlation analysis were used to analyze the relationship between standardized parathyroid FI and clinical variables. Chi square test was used to analyze the difference of parathyroid detection rate between NIRF and white light. Results: In the 51 patients, the mean standardized parathyroid FI was greater than the standardized thyroid FI (1.72 ± 0.68 vs. 1.25 ± 0.40, t=6.555, P<0.001). The standardized parathyroid FI was not associated with gender, age, operation type, BMI, preoperative serum Ca(2+), parathyroid hormone and calcitonin (all P>0.05), but it was associated with disease type (F=2.636, P<0.05). The mean standardized parathyroid FI of SHPT was lower than that of PTC, PTC with nodular goiter or NG(0.70±0.28 vs. 1.86±0.70, 1.69±0.49, 1.64±0.44, t value was 3.023, -1.129,-2.019, respectively, all P<0.05). There was no difference in the standardized parathyroid FI between SHPT and PHPT (1.34±0.18, t=1.218, P>0.05). There was no difference in standardized parathyroid FI between PHPT, PTC, NG, and PTC with NG(all P>0.05). Except for 3 cases of SHPT, 117 parathyroid glands were detected by NIRF and 101 parathyroid glands were detected by white light. The detection rate of parathyroid glands detected by NIRF was higher than that detected by white light (98.32% vs. 84.87%, χ(2)=13.974, P<0.001). In SHPT, the detection rate of parathyroid gland by NIRF was 25.00%. Conclusions: Except SHPT, parathyroid FI is not affected by other clinical variables. NIRF can improve the detection rate of parathyroid glands during operation.

Innovative Technology for Intraoperative Identification of Parathyroid Glands

Innovative Technology for Intraoperative Identification of Parathyroid Glands

Development of a Low-Cost Portable Device for Identification of Parathyroid Glands Using Autofluorescence

Intraoperative identification of parathyroid glands, which depends almost exclusively upon the surgeon’s visual acuity and experience is often a challenge in thyroid and parathyroid surgery; thus, developing a device capable of assisting the surgeon in this task will be highly useful. Demonstration of parathyroid glands’ autofluorescence when subjected to an infrared light beam of 785 nm, by Paras et al. in 2011, was followed by a few studies that confirmed the method’s value in identifying the parathyroid glands. Given the expensive nature of devices capable of inducing and detecting autofluorescence, the authors attempted to develop a low-cost, easily replicable device, based on commercially available accessories commonly used for other purposes, presented in this work, showing that autofluorescence can also be detected with inexpensive devices allowing its utilization even in hospitals with scarce economical resources.

Incidence and risk factors of inadvertent parathyroidectomy during thyroid surgery: A single-center retrospective study

Context: Thyroidectomy is considered a relatively safe surgery with morbidity of <5% when undertaken by experienced surgeons. Inadvertent parathyroidectomy (IP) means pathology report has found parathyroid tissue in the thyroid specimen, and it was reported to range from 2.9% to 31%. Aims: The aim of this study is to measure the incidence rate and to evaluate the significant relationship between risk factors and IP during thyroid surgery. Settings and Design: A retrospective chart review study was carried out in King Fahad Armed Forces Hospital, Jeddah, between June 2015 and December 2019. Subjects and Methods: All consecutive patients undergoing unilateral or bilateral thyroidectomy were enrolled in this study. Histopathology reports were reviewed to identify the specimens that included parathyroid tissue and underlying thyroid disease, and these were compared to patients with no parathyroidectomy in terms of gender, pathological features, re-operation, Hashimoto thyroiditis, extrathyroidal extension, and central neck dissection. Statistical Analysis Used: Statistical analysis was carried out using the Statistical Package for the Social Sciences. Results: Retrospective analysis of 181 consecutive thyroidectomy cases reveals that 34 (18.7%) patients had IP. Significant risk factors for IP included extra-thyroid extension (P = 0.008), total thyroidectomy (P = 0.017), and Hashimoto thyroiditis (P = 0.021). Other risk factors, including gender, malignancy, central neck dissection, and re-operation, were not statistically significant in this study. Conclusions: IP during thyroid surgery is not uncommon (18.7%). Total thyroidectomy, hashimoto thyroiditis, and extrathyroidal extension of the tumor were found to be significant risk factors. We recommend more meticulous intra-operative identification of parathyroid glands, particularly for patients with these risk factors.

Imaging or Fiber Probe-Based Approach? Assessing Different Methods to Detect Near Infrared Autofluorescence for Intraoperative Parathyroid Identification

Near infrared autofluorescence (NIRAF) can guide intraoperative parathyroid gland (PG) identification. NIRAF detection devices typically rely on imaging and fiber probe-based approaches. Imaging modalities provide NIRAF pictures on adjacent display monitors, and fiber probe-based systems measure tissue NIRAF and provide real-time quantitative information to objectively aid PG identification. Both device types recently gained FDA approval for PG identification but have never been compared directly. Patients undergoing thyroidectomy and/or parathyroidectomy were recruited prospectively. Target tissues were intraoperatively visualized with PDE-Neo II (imaging-based) and concurrently assessed with PTeye (fiber probe-based). For PDE-Neo II, NIRAF images were collected from in situ or excised tissues, alongside the surgeon's interpretation of visualized tissues, and retrospectively analyzed in a blinded fashion. The PTeye was concomitantly used to record NIRAF intensities and ratios from the same tissues in real time. Twenty patients were enrolled for concurrent evaluation with both systems, which included 33 PGs and 19 nonparathyroid sites. NIRAF imaging demonstrated 90.9% sensitivity, 73.7% specificity, and 84.6% accuracy for PG identification when interpreted in real time by the surgeon compared with 81.8% sensitivity, 73.7% specificity, and 78.8% accuracy where images were quantitatively analyzed post hoc by an independent observer. In parallel, NIRAF detection with PTeye yielded 97.0% sensitivity, 84.2% specificity, and 92.3% accuracy in real time for the same specimens. Both NIRAF-based systems were beneficial for identifying PGs intraoperatively. Although NIRAF imaging provides valuable spatial information to localize PGs, NIRAF detection with fiber probe provides real-time quantitative information to identify PGs in presence of ambient room lights.

Parathyroid identification by autofluorescence \u2013 preliminary report on five cases of surgery for primary hyperparathyroidism

BackgroundIntra-operative identification of parathyroid glands is often a challenge for surgeons performing parathyroid or thyroid surgery. Parathyroid glands stimulated by near-infrared light emit autofluorescence, which allows their discrimination from all other tissues in the region, and this may be of value during thyroid and parathyroid surgery. In this study, we present the results of the utilization of a low-cost device developed for the identification of parathyroid glands in surgery for primary hyperparathyroidism.Case presentationIn 5 patients operated in our hospital with the diagnosis of primary hyperparathyroidism and non-concordant ultrasonography and Sestamibi scan, we used a 780 nm Light Emitting Diode (LED) to stimulate the cervical area. The resulting autofluorescence was visualized with night vision goggles with a 832 nm filter assembled.In all the five patients, an easily distinguishable nodule was identified and excised, and confirmed as parathyroid adenoma by histological exam. Intra-operative PTH assay showed significant decrease compared with basal values, fulfilling the Miami Criteria for surgical success in use in our institution.ConclusionThe utilization of autofluorescence for intra-operative identification of parathyroid glands may have a clinical application in surgery for primary hyperparathyroidism, being of special utility when ultrasonography and Sestamibi Scan are non concordant.

Does fluoroscopy prevent inadvertent parathyroidectomy in thyroid surgery?

Near-infrared imaging may facilitate intraoperative identification of parathyroid glands by causing autofluorescence but its clinical value has not been established. Inadvertent parathyroidectomy occurs in 5-22% of thyroidectomies and is associated with temporary and permanent hypoparathyroidism. The aim of this study was to determine whether near-infrared imaging prevents inadvertent parathyroidectomy and early hypocalcaemia as a surrogate for permanent hypoparathyroidism. Near-infrared imaging was used in a prospective cohort of consecutive thyroidectomies. Thyroidectomies performed prior to the introduction of near-infrared imaging formed a control group. The thyroid bed and specimen were scanned with near-infrared imaging. Areas of autofluorescence on the specimen were examined and any parathyroid tissue found was autotransplanted. Inadvertent parathyroidectomy was therefore recorded as established intraoperatively by near-infrared imaging (allowing autotransplantation) or on subsequent histology (missed). Serum calcium and parathyroid hormone were measured on day one and at two weeks and six months postoperatively. A total of 269 patients were included: 106 near-infrared imaging and 163 controls. Inadvertent parathyroidectomy was detected by near-infrared imaging in two (and autotransplantation performed) and histologically (i.e. missed by near-infrared imaging in 13, 12.3% vs 17, 10.4% controls). Neither result was statistically significant (P = 0.08, 0.89). There was no significant difference in serum calcium or parathyroid hormone between near-infrared imaging and control groups at one day, two weeks or thereafter. Near-infrared imaging may detect inadvertent parathyroidectomy and may allow autotransplantation. It did not, however, reduce the incidence of missed inadvertent parathyroidectomy and no difference was seen in early hypocalcaemia or late hypoparathyroidism. Current near-infrared imaging technology does not appear to confer a clinical benefit sufficient to justify its use.

Randomized Controlled Trial Comparing White Light with Near-Infrared Autofluorescence for Parathyroid Gland Identification During Total Thyroidectomy

Parathyroid glands are difficult to identify during total thyroidectomies, and accidental resection can lead to problematic postoperative hypocalcemia. Our main goals were to evaluate the effectiveness of using near-infrared light (NIRL) autofluorescence intraoperatively for parathyroid gland identification and to measure its impact on postoperative hypocalcemia incidence. Total thyroidectomies were performed on 170 patients with different thyroid pathologies, block-randomized (1:1) into 2 equal groups. Among controls, traditional overhead white light (WL) was used throughout. In the experimental group, NIRL was used to enhance parathyroid gland recognition before thyroid dissection. The number of parathyroid glands identified was compared after thyroid dissection in controls using WL vs pre-dissection in the experimental using NIRL and with WL vs NIRL before thyroid dissection in the experimental group. Postoperative serum calcium levels and hypocalcemia rates were compared. The mean number of parathyroid glands identified pre-dissection with NIRL was the same identified post-dissection with WL (3.5 vs 3.6). In the experimental group, converting from WL to NIRL increased the number of glands detected from 2.6 to 3.5 (p < 0.001), and revealed at least 1 previously missed gland in 67.1% of patients. Calcium levels ≤7.5 mg/dL were one-tenth as common in the NIRL group (p= 0.005). The adjusted odds of hypocalcemia developing increased by 15% for every 5-g increase in thyroid gland weight (odds ratio 1.15; 95% CI 1.06 to 1.25). All hypocalcemia resolved within 6 months. Using NIRL during thyroidectomy increases intraoperative identification of parathyroid glands, enhances their detection before thyroid dissection, and decreases the incidence of postoperative hypocalcemia.

Feasibility of indocyanine green fluorescence imaging for intraoperative identification of parathyroid glands during thyroid surgery.

BackgroundThis study assessed the feasibility of near‐infrared fluorescence imaging with indocyanine green (ICG) to identify the parathyroid glands (PGs) intraoperatively and to assess their perfusion after thyroid resection.MethodsPatients undergoing elective thyroidectomy were enrolled in this prospective study. An intravenous bolus of 7.5 mg ICG was administered twice: the first bolus to identify the PGs before resection of the thyroid and the second to assess vascularization of the PGs after resection.ResultsA total of 30 operations in 26 patients were included. In 17 surgeries (56.7%), fluorescence imaging was of added value, especially to confirm the presence of a suspected PG. No intraoperative or postoperative complications occurred because of the use of ICG.ConclusionNear‐infrared fluorescence imaging with the use of ICG for intraoperative identification of the PGs and the assessment of its vascularization is feasible and safe and can provide more certainty about the location of the PGs.

Intraoperative rapid aspiration cytological method for parathyroid glands identification and protection.

To explore new methods for intraoperative identification of parathyroid glands, 86 thyroid cancer patients, admitted to Xijing hospital from July 2017 to July 2018, were included. During lymph node dissection, parathyroid glands were firstly judged by clinician eyeballing, based on his clinical experience. Then, cytological detection was used for rapid identification via Diff-quik staining. PTH monitoring was performed by PTH detection kit. Finally, frozen pathology was examined and regarded as the golden standard. In this study, 172 suspicious parathyroid glands were observed. According to frozen pathology outcome, the accuracy, sensitivity and specificity of clinician eyeballing were calculated as 63.3%, 100%, and 13.9%. Kappa test showed poor consistency (kappa = 0.156), AUC area was 0.569 ± 0.045, 95%CI = (0.480-0.658), p = 0.123. For cytological and PTH detection, the accuracy, sensitivity and specificity were 91.7% vs. 92.3%, 93.6% vs. 93.8% and 89.0% vs. 90.3%. Kappa value was 0.829 vs. 0.842, indicating good consistency. AUC area was 0.908 ± 0.027 vs. 0.918 ± 0.025, 95%CI = (0.856-0.960) vs. (0.869-0.966), p < 0.001, indicating higher diagnositic value. Besides, compared with frozen pathology, cytological detection was easily and rapid. The time-taking between frozen pathology and cytological detection or PTH detection were 39.0 ± 6.59 min vs. 5.02 ± 0.78 min and 39.0 ± 6.59 min vs. 6.1 ± 1.23 min, p < 0.001. In conclusion, intra-operative cytological detection maybe potential for in-situ preservation of parathyroid glands.

Developing a Clinical Prototype to Guide Surgeons for Intraoperative Label-Free Identification of Parathyroid Glands in Real Time.

Patients undergoing thyroidectomy may have inadvertent damage or removal of the parathyroid gland(s) due to difficulty in real-time parathyroid identification. Near-infrared autofluorescence (NIRAF) has been demonstrated as a label-free modality for intraoperative parathyroid identification with high accuracy. This study presents the translation of that approach into a user-friendly clinical prototype for rapid intraoperative guidance in parathyroid identification. A laboratory (lab)-built spectroscopy system that measures NIRAF in tissue was evaluated for identifying parathyroid glands in vivo across 162 patients undergoing thyroidectomy and/or parathyroidectomy. Based on these results, a clinical prototype called PTeye was designed with a user-friendly interface and subsequently investigated in 35 patients. The performance of the lab-built system and the clinical prototype were concurrently compared side by side by a single user with 20 patients in each group. The influence of (i) intrapatient and interpatient variability of NIRAF in thyroid and parathyroid glands and (ii) thyroid and parathyroid pathology on intraoperative parathyroid identification were investigated. The effect of blood on NIRAF intensity of parathyroid and thyroid was tested ex vivo with the PTeye system to assess if a hemorrhagic surgical field would affect parathyroid identification. Accuracy of both systems were determined by correlating the acquired data with either visual confirmation by a surgeon for unexcised parathyroid glands or histology reports for excised parathyroid glands. The overall accuracy of the lab-built system in guiding parathyroid identification was 92.5%, while the PTeye system achieved an accuracy of 96.1%. Unlike the lab-built system, the PTeye could guide parathyroid identification even as the operating room lights remained on and required only 25% of the laser power used by the lab-built setup. Parathyroid glands had elevated NIRAF intensity compared to thyroid and other neck tissues, regardless of thyroid or parathyroid pathology. Blood did not seem to affect tissue NIRAF measurements obtained with both systems. In this study, the clinical prototype PTeye demonstrated high accuracy for label-free intraoperative parathyroid identification. The intuitive interface of the PTeye that can guide in identifying parathyroid tissue in the presence of ambient room lights suggests that it is a reliable and easy-to-use tool for surgical personnel.

Intraoperative Near-infrared Imaging for Parathyroid Gland Identification by Auto-fluorescence: A Feasibility Study.

Parathyroid glands (PGs) can be particularly hard to distinguish from surrounding tissue and thus can be damaged or removed during thyroidectomy. Postoperative hypoparathyroidism is the most common complication after thyroidectomy. Very recently, it has been found that the parathyroid tissue shows near-infrared (NIR) auto-fluorescence which could be used for intraoperative detection, without any use of contrast agents. The work described here presents a histological validation ex vivo of the NIR imaging procedure and evaluates intraoperative PG detection by NIR auto-fluorescence using for the first time to our knowledge a commercially available clinical NIR imaging device. Ex vivo study on resected operative specimens combined with a prospective in vivo study of consecutive patients who underwent total or partial thyroid, or parathyroid surgery at a comprehensive cancer center. During surgery, any tissue suspected to be a potential PG by the surgeon was imaged with the Fluobeam 800 (®) system. NIR imaging was compared to conventional histology (ex vivo) and/or visual identification by the surgeon (in vivo). We have validated NIR auto-fluorescence with an ex vivo study including 28 specimens. Sensitivity and specificity were 94.1 and 80%, respectively. Intraoperative NIR imaging was performed in 35 patients and 81 parathyroids were identified. In 80/81 cases, the fluorescence signal was subjectively obvious on real-time visualization. We determined that PG fluorescence is 2.93±1.59 times greater than thyroid fluorescence in vivo. Real-time NIR imaging based on parathyroid auto-fluorescence is fast, safe, and non-invasive and shows very encouraging results, for intraoperative parathyroid identification.

Cutting Edge in Thyroid Surgery: Autofluorescence of Parathyroid Glands

Identification of parathyroid glands may be challenging during thyroid and parathyroid surgery. Accidental resection of the glands may increase the morbidity of the surgery. The aim of this study was to evaluate accuracy in identification of autofluorescent parathyroid glands with the use of near infrared light in real time. Patients undergoing thyroid and parathyroid surgery between June and August 2015 were included in the study. During the procedure, the surgical field was exposed to near infrared laser light in order to analyze the intensity of the fluorescence of different tissues (parathyroid glands, thyroid glands, and background). Surgical images were recorded and analyzed. Twenty-eight patients were included in the study. Nineteen patients were women and 9 were men. Seven patients had primary hyperparathyroidism, 4 had hyperthyroidism, 3 had goiters, and 11 had thyroid cancer. Three patients had mixed pathologies, including 2 patients with thyroid cancer and primary hyperparathyroidism and 1 patient with goiter and primary hyperparathyroidism. Identification of autofluorescent parathyroid glands was achieved in all patients with near infrared light. The mean fluorescent intensity of parathyroid glands was 40.6 (±26.5), thyroid glands 31.8 (±22.3), and background 16.6 (±15.4). Parathyroid glands demonstrated statistically higher fluorescence intensity compared with the thyroid gland and background (p < 0.0014). No postoperative hypocalcemia or other complications related to the surgery were registered. Visualization of autofluorescent parathyroid glands with the use of near infrared light allows high rates of parathyroid gland identification and could be a safe, feasible, and noninvasive method for intraoperative identification of parathyroid glands in real time. Further clinical studies must be performed to determine the cost-effectiveness and clinical application of this method.

Challenges and Limitations of Narrow-Band Optical Imaging for Intra-Operative Parathyroid Identification

Background: Surgical resection of the parathyroid glands can be challenging due to poor visual contrast between the parathyroid and surrounding tissues. We hypothesized that narrow-band imaging (NBI) could enhance subtle differences in the colors of these tissues for improved visual contrast during parathyroid surgery. Methods: The diffuse optical reflectances of parathyroid, fat, muscle, and thyroid tissue were measured in vivo as a function of wavelength during six surgical procedures, using a fiber-optic probe and spectrophotometer. Analysis of these data led to three candidate NBI wavelength bands which exhibited the largest differences in reflectance between parathyroid and other tissue types. Color filters at these wavelength bands were attached to the surgeon’s loupes for qualitative visual assessment, and also to a digital camera for quantitative assessment of tissue contrast in seven additional surgeries. Results: Spectroscopic measurements showed that diffuse optical reflectance at green (515 - 565 nm), yellow (570 - 613 nm), and red (604 - 644 nm) wavelengths showed the greatest difference in intensity (appearing brighter or darker) between parathyroid and surrounding tissues. However, visual and digital NBI of the parathyroid using these wavebands generated measured intensities which were not significantly improved as compared to white light, providing only minimal contrast enhancement for the surgeon. Conclusions: Narrow-band color filters can be added to conventional loupes to selectively view the surgical field with light at specific wavelengths. When the parathyroid is viewed with filters chosen to maximize visual contrast between tissue types, there appears to be little benefit in contrast enhancement between tissues due to diminished overall brightness. J Curr Surg. 2016;6(1):14-20 doi: http://dx.doi.org/10.14740/jcs295w

The Relationship of Intraoperative Identification of Parathyroid Glands to Postoperative Hypoparathyroidism after Total Thyroidectomy for Cancer

The Relationship of Intraoperative Identification of Parathyroid Glands to Postoperative Hypoparathyroidism after Total Thyroidectomy for Cancer

Fluorescence Identification of Parathyroid Glands by Aminolevulinic Acid Hydrochloride in Rats

In this study, we investigate the feasibility of the use of aminolevulinic acid hydrochloride (5-ALA)-induced fluorescence in the detection of parathyroid glands in rats. The intraoperative identification of parathyroid glands is difficult, which is one of the main reasons for postoperative hypoparathyroidism. An animal experiment was designed. Ten Sprague-Dawley (S-D) adult rats were injected intraperitoneally with a 300 mg/kg dosage of 5-ALA. Anesthesia and surgical dissection were performed to expose the thyroid gland 1 h later. Blue light with a wavelength of 405±3 nm was used to light the trachea bilaterally in order to detect parathyroid fluorescence by direct vision. Histology of the fluorescent tissue was performed to confirm parathyroid identification. Parathyroid gland fluorescence was visualized in all 10 S-D rats. The red fluorescence of the parathyroid glands was located on the posterolateral thyroid glands and could be seen with the naked eye. Histology of the fluorescent tissue confirmed the identification of parathyroid glands under light microscopy. 5-ALA induced fluorescence of parathyroid glands can clearly differentiate them from the surrounding tissue by direct vision alone. This method could be used intraoperatively and has potential clinical value.

The Intraluminal Use of Methylene Blue in Breast Expander Devices – A Word of Caution

In this technique, the authors inject methylene blue dye inside the lumen of the breast tissue expander in conjunction with saline so that the colour of the content turns blue for the easy identification in further injections. Although this provides an easy way to identify the port of entry of the breast tissue expander and make certain of the intraluminal placement of saline solution in future inflation sessions, the technique should not be taken lightly and a few points of caution should be raised before its universal use. Methylene blue is a tetramethylthionine chloride that belongs to a group of thiazide dyes with close chemical resemblance to phenothiazines.1 It is a potent inhibitor of guanylate, a target enzyme acted upon by nitric oxide in order to produce endothelium-dependent relaxation effect in shock condition.2 The medicinal use of methylene blue is well known. It is administered as an intravenous infusion for the intra-operative identification of parathyroid glands due to the selective uptake of the dye by the gland.3 In a small doses (1–2 mg/kg), methylene blue can be used for the treatment of methaemoglobinaemia, although in larger doses it can have the reverse effect and introduce the formation of methaemoglobin.4 Methylene blue is also used to reverse the adverse effect of nitric oxide and treat patients with anaphylactic or septic shock.2,5 In addition, methylene blue is commonly used in sentinel lymph node identification and biopsy in different types of cancer.6 Like all chemicals, there is an associated risk of developing adverse effects with the use of methylene blue. It was found in one study that when 3–5 ml of 1% methylene blue was injected intradermally for sentinel lymph node identification in breast cancer, there was a 21% incidence of developing either superficial ulceration or intense erythema at the injection site; therefore, it was recommended the dye be injected deeper in the peritumoural area to avoid such adverse effect.7,8 There are also three documented cases in the English medical literature of generalised toxicity effects when the dye is infused intravenously for the identification and localisation of parathyroid adenomas. These systemic effects were in the form of expressive aphasia, confusion, nystagmus, and myoclonic jerks. All three patients made complete recovery within 24–48 h.9–11 The use of breast expanders is associated with the risk of device leakage or complete deflation with the release of the expander contents into the breast pocket. In a 6-year follow-up study of breast reconstruction using saline-filled implants, the incidence of gradual leakage with loss of volume was 38%, while the incidence of sudden deflation that prompted re-operation was 16%.12 With the development of more modern devices, the incidence may be less but the risk is always there. The potential release of methylene blue solution inside a body cavity may be associated with a theoretical risk of local and systemic adverse effects. Keeping the amount of the used methylene blue at or below 4 mg/kg (recommended by the UK National Poisons Information Service11 as a maximum safe dose) may be a way to prevent the potential systemic hazard in case of fluid release. One last point of interest is that we believe the manufacturer device guarantee does not cover the intraluminal use of methylene blue in breast expanders in case of device failure or malfunction. In general, the benefits of using a technique should always be balanced against its potential risks and, in all cases, patients should be fully counselled to obtain their informed consent.

Intra-Operative Parathyroid Identification Using Methylene Blue in Parathyroid Surgery

The objective of this study was to determine the value of intra-operative methylene blue (MB) during parathyroid surgery. We did a retrospective study of 473 patients after initial exploration for previously untreated symptomatic primary hyperparathyroidism. Procedural and post procedural data were collected on four groups of patients: minimally invasive parathyroidectomy with MB (n = 147), and without MB (n = 205), bilateral parathyroid exploration with intra-operative parathormone assay with MB (n = 56), and without MB (n = 65). Length of surgery was shorter for patients explored with MB (P = 0.026). For the minimally invasive parathyroidectomy group, the difference between the MB and non-MB groups was seven minutes. Twelve minutes was the difference between the MB and non-MB intra-operative parathormone assay groups. Length of stay, local complications, and correction of hypercalcemia after parathyroidectomy were not significantly affected by the use of MB. Systemic complications were lower in the MB groups. Aside from a statistically significant, but quantitatively minimal decrease in the length of surgery, no consistent benefit was identified with the use of MB for intra-operative parathyroid identification.