Effect of near infrared autofluorescence guided total thyroidectomy on postoperative hypoparathyroidism: a randomized clinical trial

Exploring near-infrared autofluorescence properties in parathyroid tissue: an analysis of fresh and paraffin-embedded thyroidectomy specimens

Significance

Near-infrared autofluorescence (NIRAF) utilizes the natural autofluorescence of parathyroid glands (PGs) to improve their identification during thyroid surgeries, reducing the risk of inadvertent removal and subsequent complications such as hypoparathyroidism. This study evaluates NIRAF's effectiveness in real-world surgical settings, highlighting its potential to enhance surgical outcomes and patient safety.

Aim

We evaluate the effectiveness of NIRAF in detecting PGs during thyroidectomy and central neck dissection and investigate autofluorescence characteristics in both fresh and paraffin-embedded tissues.

Approach

We included 101 patients diagnosed with papillary thyroid cancer who underwent surgeries in 2022 and 2023. We assessed NIRAF's ability to locate PGs, confirmed via parathyroid hormone assays, and involved both junior and senior surgeons. We measured the accuracy, speed, and agreement levels of each method and analyzed autofluorescence persistence and variation over 10 years, alongside the expression of calcium-sensing receptor (CaSR) and vitamin D.

Results

NIRAF demonstrated a sensitivity of 89.5% and a negative predictive value of 89.1%. However, its specificity and positive predictive value (PPV) were 61.2% and 62.3%, respectively, which are considered lower. The kappa statistic indicated moderate to substantial agreement (kappa = 0.478; P < 0.001 ). Senior surgeons achieved high specificity (86.2%) and PPV (85.3%), with substantial agreement (kappa = 0.847; P < 0.001 ). In contrast, junior surgeons displayed the lowest kappa statistic among the groups, indicating minimal agreement (kappa = 0.381; P < 0.001 ). Common errors in NIRAF included interference from brown fat and eschar. In addition, paraffin-embedded samples retained stable autofluorescence over 10 years, showing no significant correlation with CaSR and vitamin D levels.

Conclusions

NIRAF is useful for PG identification in thyroid and neck surgeries, enhancing efficiency and reducing inadvertent PG removals. The stability of autofluorescence in paraffin samples suggests its long-term viability, with false positives providing insights for further improvements in NIRAF technology.

The role of parathyroid autotransplantation for hypoparathyroidism following total thyroidectomy with bilateral central neck dissection

Background

Hypoparathyroidism is the most common complication for patients who undergo total thyroidectomy (TT) with bilateral central lymph node dissection (BCLND). The objective of this retrospective study was to investigate the relationship between parathyroid autotransplantation (PA) and postoperative hypoparathyroidism.

Materials and Methods

Four hundred and sixty-five patients with papillary thyroid carcinoma (PTC) who underwent TT with BCLND (including prophylactic and therapeutic BCLND) by the same surgeon were enrolled in this retrospective study. They were divided into five groups based on the number of PAs. Group 0 was defined as no PA, while Group 1, 2, 3, and 4 were considered as 1, 2, 3, and 4 PAs during TT with BCLND, respectively.

Results

Transient and permanent hypoparathyroidism occurred in 83 (17.8%) and 2 (0.4%) patients who underwent TT and BCLND, respectively. The incidence of transient hypoparathyroidism increased gradually with an increase in the number of PAs. Compared with the previous group, Groups 2 and 3 had significantly more cases of transient hypoparathyroidism (p=0.03 and p=0.04, respectively). All cases of permanent hypoparathyroidism occurred in the patients without PA. Compared with Group 0, there were more removed central lymph nodes (RCLNs) in patients with one PA. Furthermore, Group 2 had more metastatic central lymph nodes(MCLNs) and RCLNs than Group 1.The number of PAs was the only identified risk factor for transient hypoparathyroidism after the multivariate logistic regression analysis. The median parathyroid hormone level recovered to the normal range within 1 month after surgery.

Conclusion

With an increasing number of PAs, the possibility of transient hypoparathyroidism also increases in patients with PTC who undergo TT and BCLND. Considering the rapid recovery of transient hypoparathyroidism in 1 month, two PAs during TT and BCLND could be a good choice, leading to an increase in the central lymph node yield and no permanent hypoparathyroidism. However, this conclusion should be validated in future multicenter prospective studies.

The impact of using near-infrared autofluorescence on parathyroid gland parameters and clinical outcomes during total thyroidectomy: a meta-analytic study of randomized controlled trials

BACKGROUND

The added benefit of using near-infrared autofluorescence (NIRAF) during total thyroidectomy (TT) remains controversial. This study investigated whether or not NIRAF results in improved patient outcomes postoperatively.

MATERIALS AND METHODS

We analyzed 1711 TT patients, reported in nine randomized controlled trials, following a systematic search of five databases. NIRAF was compared to the standard of care (naked eye with/without white light). Outcomes included parathyroid gland (PG) and calcium parameters and other clinical outcomes. For dichotomous outcomes, the log odds ratio (logOR) was calculated, and for continuous outcomes, the crude mean difference (MD) was measured. Sensitivity analysis was performed when heterogeneity was significant. The revised Cochrane risk of bias tool was used to assess the methodological quality.

RESULTS

Compared to the standard of care, the use of NIRAF was associated with a significant reduction in postoperative hypoparathyroidism [logOR=-0.31; 95% CI: -0.57: -0.05], inadvertent PG removal [logOR=-0.93; 95% CI: -1.60: -0.26], and postoperative hypocalcemia [logOR=-0.43 mmol/l; 95% CI: -0.77: -0.09]. It was also associated with significantly higher postoperative PTH levels [MD=4.78 pg/ml; 95% CI: 2.13: 7.43], PG identification rate [logOR=1.02; 95% CI: 0.31: 1.72], postoperative serum calcium [MD=0.05; 95% CI: 0.00: 0.09], and operative time [MD=9.38 min; 95% CI: 6.68: 12.09]. No difference was seen regarding PG autotransplantation, length of hospital stay, and hospitalization due to hypocalcemia. Seven trials had low risk and the remainder had some concerns.

CONCLUSION

NIRAF is superior to the naked eye in identifying all four PGs during TT. The reduced risk of postoperative hypoparathyroidism and hypocalcemia reflected this preservation value. However, it was not associated with a change in the length of hospital stay. Although rare, the readmission rate due to hypocalcemia was similar across both methods.

Autofluorescence-Guided Total Thyroidectomy in Low-Volume, Nonparathyroid Institutions

Importance

Hypoparathyroidism following thyroid surgery is a serious complication that occurs frequently when surgery is performed by low-volume thyroid surgeons without experience in parathyroid surgery.

Objective

To evaluate the occurrence of hypoparathyroidism following total thyroidectomy after the introduction of autofluorescence in low-volume, nonparathyroid institutions.

Design, Setting, and Participants

This prospective, multicenter cohort study, with a follow-up period of up to 1 year, was conducted in Denmark at 2 low-volume nonparathyroid institutions between January 2021 and November 2023. All adult patients referred for total thyroidectomy were assessed for eligibility (n = 90). Only patients with no history of thyroid surgery were considered (n = 89). Patients who only underwent lobectomy (n = 6) or declined to participate (n = 5) were excluded. All included patients completed follow-up. The prospective cohort was compared with a historical cohort of successive patients undergoing primary total thyroidectomy from 2016 to 2020 (before autofluorescence was available).

Intervention

Included patients underwent autofluorescence-guided total thyroidectomy.

Main outcomes and Measures

Rate of hypoparathyroidism. Immediate hypoparathyroidism was defined as the need for active vitamin D postoperatively, whereas permanent hypoparathyroidism was considered when there still was a need for active vitamin D 1 year after surgery.

Results

Seventy-eight patients underwent autofluorescence-guided surgery (mean [SD] age, 55.6 [13.1] years; 67 [86%] female) and were compared with 89 patients in the historical cohort (mean [SD] age, 49.7 [12.8] years; 78 [88%] female). The rate of immediate hypoparathyroidism decreased from 37% (95% CI, 27%-48%) to 19% (95% CI, 11%-30%) after the introduction of autofluorescence (P = .02). Permanent hypoparathyroidism rates decreased from 32% (95% CI, 22%-42%) to 6% (95% CI, 2%-14%) (P < .001), reaching 0% at the end of the study. More parathyroid glands were identified with autofluorescence (75% [95% CI, 70%-80%] vs 61% [95% CI, 56%-66%]) (P < .001) and less parathyroid glands were inadvertently excised (4% [95% CI, 1%-11%] vs 21% [95% CI, 13%-31%]) (P = .001).

Conclusions and Relevance

In this cohort study of autofluorescence-guided thyroid surgery in low-volume, nonparathyroid institutions, the use of autofluorescence was associated with a significant decrease in both immediate and permanent hypoparathyroidism. When autofluorescence was used, hypoparathyroidism rates were comparable with those of high-volume surgeons who also perform parathyroid surgery.

Autofluorescence-guided hemithyroidectomy in a low-volume thyroid institution with no experience in parathyroid surgery: randomized clinical trial

BACKGROUND

Recent studies suggest that low-volume surgeons with no experience in parathyroid surgery are at increased risk of causing parathyroid gland damage during thyroid surgery. The aim of this RCT was to evaluate the impact of using autofluorescence in hemithyroidectomy on parathyroid gland identification and preservation in a low-volume institution with no experience in parathyroid surgery.

METHODS

Patients referred for hemithyroidectomy were randomized 1 : 1 to either autofluorescence-guided hemithyroidectomy (the near-infrared autofluorescence group) or conventional hemithyroidectomy (the control group). The primary outcome was parathyroid gland identification rate. Secondary outcomes were the rate of parathyroid gland autotransplantation and the rate of inadvertent parathyroid gland excision.

RESULTS

A total of 170 patients were randomized to either autofluorescence-guided hemithyroidectomy (84 patients) or conventional hemithyroidectomy (86 patients). In the near-infrared autofluorescence group, 81.0% of parathyroid glands were identified, compared with 57.0% in the control group (P < 0.001). Autofluorescence enabled parathyroid gland visualization before the naked eye in 46.3% of cases. Surgeons had lower confidence in the parathyroid gland identification process in the control group than in the near-infrared autofluorescence group (59.1% versus 87.5% respectively; P < 0.001). In the near-infrared autofluorescence group, the parathyroid gland autotransplantation rate was initially high, but declined over time. There was no difference in the rate of inadvertent parathyroid gland excision.

CONCLUSION

Autofluorescence guidance significantly improved the parathyroid gland identification rate in hemithyroidectomy in a low-volume institution with no experience in parathyroid surgery and provided an increase in surgical confidence. The pattern of parathyroid gland autotransplantation in autofluorescence-guided surgery indicates the presence of a learning curve.

REGISTRATION NUMBER

NCT05044351 (http://www.clinicaltrials.gov).

Intraoperative strategies in identification and functional protection of parathyroid glands for patients with thyroidectomy: a systematic review and network meta-analysis

BACKGROUND

This study aimed to assess the benefits and limitations of four intraoperative visualization of parathyroid gland (IVPG) strategies in the identification and functional protection of parathyroid glands (PGs).

METHODS

We searched PubMed, the Cochrane Central Register of Controlled Trials, CNKI, EMBASE, Web of Science and Google Scholar databases until 30 June 2023. Four IVPG strategies were composed of the naked eyes (NE) and three imaging strategies: autofluorescence (AF), indocyanine green fluorescence (ICGF), and carbon nanoparticles (CN). We performed a pairwise meta-analysis (PMA) for direct comparisons and a Bayesian network meta-analysis (NMA) for indirect comparisons.

RESULTS

A total of 29 eligible studies were included. According to NMA and PMA, AF had significantly lower rates of postoperative hypocalcemia and hypoparathyroidism, PG inadvertent resection, and PG auto-transplantation compared to NE, while had significantly higher rate of PG identification. CN showed significantly lower rates of postoperative hypocalcemia and hypoparathyroidism, and PG inadvertent resection compared to NE in PMA and NMA. ICGF showed a significantly higher rate of PG auto-transplantation compared to NE in PMA and AF in NMA. According to SUCRA values, AF showed the best advantage in reducing the rate of postoperative hypocalcemia (0.85) and PG inadvertent resection (0.89), and increasing the rate of PG identification (0.80). CN had the greatest advantage in reducing the rate of postoperative hypoparathyroidism (0.95). ICGF ranked the highest in the rate of PG auto-transplantation (0.98).

CONCLUSIONS

Three imaging strategies demonstrate significant superiority over NE in the intraoperative PG identification and functional protection. AF is the best strategy in reducing the incidence of postoperative hypocalcemia, increasing the rate of PG identification, and reducing the rate of PG inadvertent resection and auto-transplantation. ICGF has great value in assessing PG viability, leading to the trend towards PG auto-transplantation. CN is the best strategy in reducing the incidence of postoperative hypoparathyroidism.

Lower Rates of Hypocalcemia Following Near-Infrared Autofluorescence Use in Thyroidectomy: A Meta-Analysis of RCTs

BACKGROUND

Iatrogenic injury of the parathyroid glands is the most frequent complication after total thyroidectomy.

OBJECTIVE

To determine the effectiveness of near-infrared autofluorescence (NIRAF) in reducing postoperative hypocalcemia following total thyroidectomy.

METHODS

PubMed, Scopus, and Google Scholar databases were searched. Randomised trials reporting at least one hypocalcemia outcome following total thyroidectomy using NIRAF were included.

RESULTS

The qualitative data synthesis comprised 1363 patients from nine randomised studies, NIRAF arm = 636 cases and non-NIRAF arm = 637 cases. There was a statistically significant difference in the overall rate of hypocalcemia log(OR) = -0.7 [(-1.01, -0.40), M-H, REM, CI = 95%] and temporary hypocalcemia log(OR) = -0.8 [(-1.01, -0.59), M-H, REM, CI = 95%] favouring the NIRAF. The difference in the rate of permanent hypocalcemia log(OR) = -1.09 [(-2.34, 0.17), M-H, REM, CI = 95%] between the two arms was lower in the NIRAF arm but was not statistically significant.

CONCLUSIONS

NIRAF during total thyroidectomy helps in reducing postoperative hypocalcemia. Level of evidence-1.

Hypoparathyroidism following total thyroidectomy: high rates at a low-volume, non-parathyroid institution

Background

Hypoparathyroidism following total thyroidectomy is globally the most common complication to thyroid surgery. The reported complication rates vary widely and might be highly dependent on the surgical experience. In this study we aimed to evaluate the rate of hypoparathyroidism following primary total thyroidectomy at a low-volume institution that only performs thyroid surgery and does not have any experience with parathyroid surgery.

Methods

Retrospective cohort study. All patients undergoing primary total thyroidectomy at the ENT-Department, Goedstrup Hospital, Denmark, over a 5-year period (2016-2020) were identified through the procedure codes for total thyroidectomy. Medical records, pathology reports, biochemical and medical histories were fully assessed for each patient. The primary endpoint was the rate of hypoparathyroidism- both immediate and permanent. Secondary outcomes were parathyroid gland identification rates, rates of parathyroid gland autotransplantation, and rates of inadvertent parathyroid gland excision.

Results

A total of 89 patients were included in the final analysis. A total of 33 patients (37.1%) experienced immediate hypoparathyroidism following surgery, while 30 patients (33.7%) still were on active vitamin D two months postoperatively. One year following surgery, 28 patients (31.5%) were still on active vitamin D and were considered as having permanent hypoparathyroidism. Sixty-one percent of the parathyroid glands were identified intraoperatively, and 19% of the patients experienced parathyroid autotransplantation. Inadvertent parathyroid gland excision occurred for 21% of the patients and was associated with a significantly increased risk of permanent hypoparathyroidism (RR = 2.99; 95% CI: 1.36 - 6.62, p = 0.005).

Conclusion

Both transient and permanent hypoparathyroidism following total thyroidectomy at a low-volume, non-parathyroid institution occurred with much higher frequencies than previously reported. The elevated rates were most likely due to the low-volume, non-parathyroid nature of the surgeons which in part was mirrored in low parathyroid gland identifications rates, and high rates of autotransplantation and inadvertent parathyroid gland excision.