Indocyanine green angiography to evaluate immediate hypoparathyroidism after thyroid cancer surgery

Indocyanine green (ICG) fluorescence angiography has been introduced to assess parathyroid perfusion intraoperatively. This study aimed to evaluate whether the number of well-vascularized parathyroid glands identified using ICG fluorescence could predict the maintenance of adequate parathyroid hormone (PTH) levels in the immediate postoperative period.

A retrospective study was conducted on 150 consecutive patients who underwent total thyroidectomy for papillary thyroid cancer between March 2021 and December 2023. Parathyroid perfusion was assessed using ICG fluorescence angiography, and glands were classified on a scale from 0 (no vascularization) to 2 (good vascularization). PTH levels were measured 1 h postoperatively, and biochemical hypoparathyroidism was defined as PTH < 15 pg/dL. Statistical analyses were performed using Fisher's exact test and Chi-square test, with p < 0.05 considered significant.

Transient biochemical hypoparathyroidism occurred in 34.7% of patients. Among patients with two or more well-vascularized parathyroid glands (score 2), 70.2% did not experience a decrease in parathyroid hormone levels below 15 pg/mL (NPV 70.2%, 95% CI: 62.4-78.1%). However, 29.8% of patients with two or more well-vascularized glands still developed hypoparathyroidism, highlighting the limitations of using this metric alone to predict postoperative outcomes. The overall accuracy for predicting hypoparathyroidism was 70% (95% CI: 62.7-77.3%). No patient developed permanent hypoparathyroidism.

ICG fluorescence angiography is a reliable tool for assessing parathyroid gland perfusion during thyroidectomy. However, the identification of two or more well-vascularized parathyroid glands does not completely exclude the risk of transient hypoparathyroidism, indicating that additional factors must be considered in predicting postoperative outcomes.