Intraoperative Mapping Angiograms of the Parathyroid Glands Using Indocyanine Green During Thyroid Surgery: Results of the Fluogreen Study

During thyroid surgery, preservation of parathyroid gland (PG) feeding vessels is often impossible. The aim of the Fluogreen study was to determine the feasibility of using indocyanine green (ICG)-based intraoperative mapping angiograms of the PG (iMAP) to improve vascular preservation.

This prospective study enrolled all patients undergoing thyroid lobectomy or total thyroidectomy at the Hôpital Européen Marseille between September and December 2018. After exploring the thyroid lobe by autofluorescence to locate the PGs, ICG solution was injected intravenously to locate the PG feeding vessels and guide dissection. A second ICG injection was administered at the end of the lobectomy to assess perfusion of the PGs. The primary outcome was the quality of the angiogram, scaled as iMAP 0 (not informative), iMAP 1 (general vascular pattern visible but no clear vascular pedicle flowing into the PG), or iMAP 2 (clear vascular pedicle flowing into the PG). The secondary outcome was the PG perfusion score at the end of surgery, scaled from ICG 0 (no perfusion) to ICG 2 (intense uptake).

A total of 47 adult patients were analyzed, including 34 total thyroidectomies and 13 lobectomies. ICG angiography assessed 76 PGs, which were scored as iMAP 2 in 24 cases (31.6%), iMAP 1 in 46 (60.5%) and iMAP 0 in six (7.9%). At the end of dissection, the ICG perfusion score was significantly better for the PGs with informative angiography (iMAP 1 or 2), than for the PGs with uninformative angiography (iMAP 0), or the PGs not evaluated by vascular angiography (p < 0.05).

iMAP is feasible and provides direct vascular information in one-third of the cases. Further improvements to this technology are necessary, and the influence of this technique on patient outcomes during thyroidectomy will need to be further evaluated.