title: Assisted hepatic resection using a toroidal HIFU device: an in vivo comparative study in pig.
abstract: OBJECTIVE
  Bleeding is the main cause of postoperative complications during hepatic surgery. Blood loss and transfusions increase tumor recurrence in liver metastases from colorectal cancer. A high intensity focused ultrasound (HIFU) device with an integrated ultrasound imaging probe was developed for the treatment of colorectal liver metastasis.
  
  
  METHODS
  The HIFU toroidal-shaped transducer contains 256 elements (working frequency: 3 MHz) and can create a single conical lesion of 7 cm3 in 40 s. Then, the volume of treatment can be significantly increased by juxtaposing single lesions. Presented here is the use of this device in an animal model as a complementary tool to improve surgical resection in the liver. Before transecting the liver, a wall of coagulative necrosis was performed using this device in order to minimize blood loss and dissection time during hepatectomy. Resection assisted by HIFU was compared to classical dissections with clamping [intermittent Pringle maneuver (IPM) group] and without clamping (control group). For each technique, 14 partial liver resections were performed in seven pigs. Blood loss per dissection surface area and resection time were the main outcome parameters.
  
  
  RESULTS
  Conserving liver blood inflow during hepatic resection assisted by HIFU did not increase total blood loss (7.4 +/- 3.3 ml cm(-2)) compared to hepatic resection performed during IPM and controlled blood inflow (11.2 +/- 2.2 ml cm(-2)). Lower blood loss was measured on average when using HIFU, even though difference with clamping (IPM) was not statistically significant (p = 0.09). Resection assisted by HIFU reduced blood loss by 50% compared to control group (14.0 +/- 3.4 ml cm(-2), p = 0.03). The duration of transection when using HIFU (13 +/- 3 min) was significantly lower compared to clamping (23 +/- 4 min, p < 0.01) and control (18 +/- 3 min, p = 0.02). Precoagulation also resulted in sealing blood vessels with a diameter of less than 5 mm, and therefore the number of clips needed in the HIFU group was significantly lower (0.8 +/- 0.2 cm(-2)) when compared to clamping (1.6 +/- 0.2 cm(-2), p < 0.01) and control (1.8 +/- 0.4 cm(-2), p < 0.01).
  
  
  CONCLUSIONS
  This method holds promise for future clinical applications in resection of liver metastases.
authors.affiliation: INSERM, Therapeutic Application of Ultrasound, U1032, Lyon F-69003, France.
authors.forename: W A
authors.initials: WA
authors.lastname: N'Djin
authors.forename: D
authors.initials: D
authors.lastname: Melodelima
authors.forename: F
authors.initials: F
authors.lastname: Schenone
authors.forename: M
authors.initials: M
authors.lastname: Rivoire
authors.forename: J Y
authors.initials: JY
authors.lastname: Chapelon
mesh_terms: D000818:Animals; D016063:Blood Loss, Surgical / Q000517:prevention & control; D005260:Female; D057086:High-Intensity Focused Ultrasound Ablation / Q000295:instrumentation*; D008099:Liver / Q000166:cytology / Q000601:surgery*; D013552:Swine; D013997:Time Factors