title: High-intensity focused ultrasound ablation of thyroid nodules: first human feasibility study.
abstract: BACKGROUND
  Thyroid surgery is common, but complications may occur. High-intensity focused ultrasound (HIFU) is a minimally invasive alternative to surgery. We hypothesized that an optimized HIFU device could be safe and effective for ablating benign thyroid nodules without affecting neighboring structures.
  
  
  METHODS
  In this open, single-center feasibility study, 25 patients were treated with HIFU with real-time ultrasound imaging 2 weeks before a scheduled thyroidectomy for multinodular goiter. Thyroid ultrasonography imaging, thyroid function, were evaluated before and after treatment. Adverse events were carefully recorded. Each patient received HIFU for one thyroid nodule, solid or mixed, with mean diameter ≥8 mm, and no suspicion of malignancy. The HIFU device was progressively adjusted with stepwise testing. The energy level for ablation ranged from 35 to 94 J/pulse for different groups of patients. One pathologist examined all removed thyroids.
  
  
  RESULTS
  Three patients discontinued treatment due to pain or skin microblister. Among the remaining 22 patients, 16 showed significant changes by ultrasound. Macroscopic and histological examinations showed that all lesions were confined to the targeted nodule without affecting neighboring structures. At pathological analysis, the extent of nodule destruction ranged from 2% to 80%. Five out of 22 patients had over 20% pathological lesions unmistakably attributed to HIFU. Seventeen cases had putative lesions including nonspecific necrosis, hemorrhage, nodule detachment, cavitations, and cysts. Among these 17 cases, 12 had both ultrasound changes and cavitation at histology that may be expected for an HIFU effect. In the last three patients ablated at the highest energy level, significant ultrasound changes and complete coagulative necrosis were observed in 80%, 78%, and 58% of the targeted area, respectively. There were no major complications of ablation.
  
  
  CONCLUSIONS
  This study showed the potential efficacy of HIFU for human thyroid nodule ablation. Lesions were clearly visible by histology and ultrasound after high energy treatments, and safety and tolerability were good. We identified a power threshold for optimal necrosis of the target thyroid tissue. Further studies are ongoing to assess nodule changes at longer follow-up times.
authors.affiliation: ENT & Cervicofacial Surgery (Private Practice), Paris, France. olivier.esnault@wanadoo.fr
authors.forename: Olivier
authors.initials: O
authors.lastname: Esnault
authors.forename: Brigitte
authors.initials: B
authors.lastname: Franc
authors.forename: Fabrice
authors.initials: F
authors.lastname: Ménégaux
authors.forename: Agnès
authors.initials: A
authors.lastname: Rouxel
authors.forename: Eric
authors.initials: E
authors.lastname: De Kerviler
authors.forename: Pierre
authors.initials: P
authors.lastname: Bourrier
authors.forename: François
authors.initials: F
authors.lastname: Lacoste
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Chapelon
authors.forename: Laurence
authors.initials: L
authors.lastname: Leenhardt
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004867:Equipment Design; D005240:Feasibility Studies; D005260:Female; D006044:Goiter, Nodular / Q000175:diagnosis / Q000601:surgery*; D057086:High-Intensity Focused Ultrasound Ablation / Q000009:adverse effects / Q000295:instrumentation; D006801:Humans; D008297:Male; D008875:Middle Aged; D009336:Necrosis; D010297:Paris; D013960:Thyroid Function Tests; D016606:Thyroid Nodule / Q000175:diagnosis / Q000601:surgery*; D013965:Thyroidectomy; D013997:Time Factors; D016896:Treatment Outcome; D018608:Ultrasonography, Doppler