Abstract Background Indocyanine green (ICG) angiography is used to assess parathyroid gland perfusion after thyroidectomy to reduce rates of hypocalcemia. This study was conducted to evaluate the efficacy of probe-based fluorescence detection of parathyroid glands with ICG for quantitative perfusion assessment. Methods Patients undergoing endocrine neck surgery were recruited for a prospective study. Parathyroid glands were identified intraoperatively using near infrared autofluorescence (NIRAF) with a probe-based system. A 0. 25 mg dose of ICG was administered to patients before surgical closure, and the fluorescence from the parathyroid gland was measured 3 min after injection and compared with pre-ICG NIRAF. Images from ICG angiography were collected and scored by three surgeons to analyze inter-rater variability. Probe-measured ICG ratios were compared with ICG image scores to determine the utility of probe-based ICG perfusion quantification in parathyroid glands. Results This study analyzed 25 patients. Analysis of ICG image scores showed moderate agreement (κ = 0. 48–0. 58). However, there was significant disagreement when glands with poor blood flow, validating the need for a quantitative approach in ICG angiography. A metric of probe-measured fluorescence change after ICG was developed to classify ligated and untouched glands from parathyroidectomies. A ≤ 1. 0-fold increase in fluorescence corresponded with devascularized glands, whereas a ≥ 4. 5. -fold increase identified well-vascularized glands. Fluorescence between 1. 0 1. 0 - and 4. 5 4. 5 -fold identified glands with poor flow. Conclusion Scoring of ICG angiography is highly subjective and varies significantly among surgeons. However, probe-based fluorescence measurements after low-dose ICG administration can quantitatively predict the vascularity status of parathyroid glands.
Willmon et al. (Fri,) studied this question.