Procedure
PATHOLOGY, DISSECTION, THYROID GLAND
Referring to the “Perrier” nomenclature (Classification and schematic diagram of the parathyroid glands according to the surgical exploration process.The operation can be performed from cephalic to caudal or from caudal to cephalic, in accordance with the surgeon’s preference. Because the autofluorescence signal of parathyroid glands is best when imaging in vertical direction, the imaging head of the camera must be rotated slightly during localization. To reduce the imaging frequency, the procedure can be divided into several phases (P1-P6). The following is an example from the right side.P1: Lateral thyroid dissection. The middle vein can be cut close to the thyroid gland to dissect the fascial tissue on the lateral side of the thyroid. Then the NIRAF camera was moved from the lateral to the medial side to capture the fluorescence signal from the parathyroid glands (
P2: Dissection of the thyrothymic ligament. After separating the junction of the thyrothymic ligament and thyroid gland, the thyroid gland was pulled upward and inward. The dorsal surfaces of the thyroid and thyrothymic ligament were detected (
P3: Ligation of tertiary vessels on the thyroid surface. 1) The anterior branch of the superior thyroid artery was disconnected and the superior pole of the thyroid was lifted. The superior parathyroid gland was searched from the direction of the superior blood vessel to the point where the recurrent laryngeal nerve entered the larynx (
P4: Thyroid gland removal. The surrounding tissue was then stretched, and the tracheoesophageal groove was exposed. The camera should be positioned directly above and with a search for parathyroid glands that were hidden deep in the tracheoesophageal groove or covered by other tissues (
P5: Central neck dissection. The recurrent laryngeal nerve was dissected, and the tissues at level VI and thymus were exposed. The thymic tongue was pulled upwards with imaging from the cephalic to caudal side toward the proximal end of the recurrent laryngeal nerve (P6: Examination of isolated specimens. After the specimen was obtained, it was sent to the pathology department for frozen section or paraffin section examination. Before that, all tissues that had been removed were placed on gauze to carefully check whether there was any parathyroid gland that had been inadvertently removed (
The parathyroid gland identified in the paraffin pathology was recorded as P7. PX was recorded if no parathyroid gland was located during surgery or found in a postoperative specimen.The NIRAF and control groups both underwent the same surgical procedure. The main difference was that, in the NIRAF group, the position of the parathyroid glands was preferentially identified, and then the surrounding blood vessels and connective tissue were retrogradely dissected towards the superior thyroid artery or inferior artery. In the control group, the parathyroid glands were identified by the naked eye during dissection from the surrounding tissue with increased risk of damaging their blood supply vessels.