title: Feasibility Study on MR-Guided High-Intensity Focused Ultrasound Ablation of Sciatic Nerve in a Swine Model: Preliminary Results.
abstract: BACKGROUND
  Spastic patients often seek neurolysis, the permanent destruction of the sciatic nerve, for better pain management. MRI-guided high-intensity focused ultrasound (MRgHIFU) may serve as a noninvasive alternative to the prevailing, more intrusive techniques. This in vivo acute study is aimed at performing sciatic nerve neurolysis using a clinical MRgHIFU system.
  
  
  METHODS
  The HIFU ablation of sciatic nerves was performed in swine (n = 5) using a HIFU system integrated with a 3 T MRI scanner. Acute lesions were confirmed using T1-weighted contrast-enhanced (CE) MRI and histopathology using hematoxylin and eosin staining. The animals were euthanized immediately following post-ablation imaging.
  
  
  RESULTS
  Reddening and mild thickening of the nerve and pallor of the adjacent muscle were seen in all animals. The HIFU-treated sections of the nerves displayed nuclear pyknosis of Schwann cells, vascular hyperemia, perineural edema, hyalinization of the collagenous stroma of the nerve, myelin sheet swelling, and loss of axons. Ablations were visible on CE MRI. Non-perfused volume of the lesions (5.8-64.6 cc) linearly correlated with estimated lethal thermal dose volume (4.7-34.2 cc). Skin burn adjacent to the largest ablated zone was observed in the first animal. Bilateral treatment time ranged from 55 to 138 min, and preparation time required 2 h on average.
  
  
  CONCLUSIONS
  The acute pilot study in swine demonstrated the feasibility of a noninvasive neurolysis of the sciatic nerve using a clinical MRgHIFU system. Results revealed that acute HIFU nerve lesions were detectable on CE MRI, gross pathology, and histology.
authors.affiliation: Department of Medical Physics, Memorial Sloan Kettering Cancer Center, 1275 York Ave, New York, NY, 10065, USA, kayee@mskcc.org.
authors.forename: Elena A
authors.initials: EA
authors.lastname: Kaye
authors.forename: Narendra Babu
authors.initials: NB
authors.lastname: Gutta
authors.forename: Sebastien
authors.initials: S
authors.lastname: Monette
authors.forename: Amitabh
authors.initials: A
authors.lastname: Gulati
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Loh
authors.forename: Govindarajan
authors.initials: G
authors.lastname: Srimathveeravalli
authors.forename: Paula C
authors.initials: PC
authors.lastname: Ezell
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Erinjeri
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Solomon
authors.forename: Majid
authors.initials: M
authors.lastname: Maybody
mesh_terms: D000818:Animals; D005240:Feasibility Studies; D057086:High-Intensity Focused Ultrasound Ablation; D053783:Magnetic Resonance Imaging, Interventional; D023421:Models, Animal; D010865:Pilot Projects; D012584:Sciatic Nerve / Q000601:surgery*; D013552:Swine