Ultrasound-guided percutaneous thermal ablation for benign parathyroid nodules

Abstract

Objective To establish treatment strategies using percutaneous radiofrequency ablation(RFA) and microwave ablation(MWA) for benign parathyroid nodules and to investigate the related techniques,procedures,safety and efficacy. Methods Percutaneous RFA and MWA were conducted on 317 benign parathyroid nodules in 96 patients using an auto-controlled bi-polar electrode system(Celon ProBreath,Germany) and thyroid-specified microwave antenna(Thy-ablationTM,China).The ablation strategy,optimal puncture route,protection of vital neck vessels and recurrent laryngeal nerve,reduction of bleeding from core-needle biopsy,indicator for complete therapy,ablation time(AT) for single nodule,and total operation time(TOT) for each case were investigated and analyzed.The focal changes of ablated region on multimode ultrasound,serum parathyroid hormone(PTH) level,serum calcium values,clinical manifestations and pathological alterations were assessed during follow-up. Results Cross section simultaneously demonstrating the ablation target,ablation needles and vital anatomic structures was essential for a safe ablation procedure of parathyroid lesions.Liquid isolating zone maneuver was beneficial for creating safe puncture route and for protecting laryngeal nerves,esophagus and trachea from heat damage."Thermal blocking of blood flow" prior to core-needle biopsy effectively reduced bleeding and successfully treated one patient with intensive subcutaneous hemorrhage.Contrast-enhanced ultrasound was an important and essential indicator for a complete therapy.In primary hyperparathyroidism(PHPT) group the TOT for each case was about(572.47±75.79) s and AT for single nodule was about(194.82±46.39) s,and the numbers in secondary hyperparathyroidism(SHPT) group were(1 548.47± 323.83) s and(217.55±52.42) s,respectively.Two months after ablation,the ablated region began to shrink,and RFA was superior to MWA regarding the speed and extent of shrinkage.At the end of twelfth month,ultrasound scanning revealed that the ablated region was completely dissolved in 73.1%(19/26) of nodules in PHPT group and 53.6%(156/291) of nodules in SHPT.Pre-ablative 99mTc-MIBI disclosed 93.1%(295/317) of the parathyroid lesions and none of them were visible after ablation.Ultrasound elastography disclosed hardening of the ablated region,and it gradually became soft,paralleling with shrinkage of the ablated region.Serum PTH level decreased rapidly after ablation,particularly in PHPT patients.In the later course PTH levels had relapse in some patients,but the relapses were quite different in timing and extent between PHPT and SHPT groups.Two cases with hyperparathyroidism crisis regained consciousness two hours after ablation therapy. Conclusion Ultrasound-guided percutaneous thermal therapy of parathyroid benign nodules is a new modality of surgical intervention for hyperparathyroidism.The ablative procedure is precise,accurate,safe,and time-saving.The lesion can be completely inactivated and the absorbed.Rapid dropping of PTH level makes it valuable for emergency treatment of crisis.The relapse of PTH may indicate new parathyroid lesion.