title: An Ultrasound Image-Based Dynamic Fusion Modeling Method for Predicting the Quantitative Impact of In Vivo Liver Motion on Intraoperative HIFU Therapies: Investigations in a Porcine Model.
abstract: Organ motion is a key component in the treatment of abdominal tumors by High Intensity Focused Ultrasound (HIFU), since it may influence the safety, efficacy and treatment time. Here we report the development in a porcine model of an Ultrasound (US) image-based dynamic fusion modeling method for predicting the effect of in vivo motion on intraoperative HIFU treatments performed in the liver in conjunction with surgery. A speckle tracking method was used on US images to quantify in vivo liver motions occurring intraoperatively during breathing and apnea. A fusion modeling of HIFU treatments was implemented by merging dynamic in vivo motion data in a numerical modeling of HIFU treatments. Two HIFU strategies were studied: a spherical focusing delivering 49 juxtapositions of 5-second HIFU exposures and a toroidal focusing using 1 single 40-second HIFU exposure. Liver motions during breathing were spatially homogenous and could be approximated to a rigid motion mainly encountered in the cranial-caudal direction (f = 0.20 Hz, magnitude > 13 mm). Elastic liver motions due to cardiovascular activity, although negligible, were detectable near millimeter-wide sus-hepatic veins (f = 0.96 Hz, magnitude < 1 mm). The fusion modeling quantified the deleterious effects of respiratory motions on the size and homogeneity of a standard "cigar-shaped" millimetric lesion usually predicted after a 5-second single spherical HIFU exposure in stationary tissues (Dice Similarity Coefficient: DSC < 45%). This method assessed the ability to enlarge HIFU ablations during respiration, either by juxtaposing "cigar-shaped" lesions with spherical HIFU exposures, or by generating one large single lesion with toroidal HIFU exposures (DSC > 75%). Fusion modeling predictions were preliminarily validated in vivo and showed the potential of using a long-duration toroidal HIFU exposure to accelerate the ablation process during breathing (from 0.5 to 6 cm3 · min(-1)). To improve HIFU treatment control, dynamic fusion modeling may be interesting for assessing numerically focusing strategies and motion compensation techniques in more realistic conditions.
authors.affiliation: LabTAU, Inserm U1032, Institut National de la Santé et de la Recherche Médicale, Lyon, France; Université Claude Bernard Lyon 1, Lyon, France.
authors.forename: W Apoutou
authors.initials: WA
authors.lastname: N'Djin
authors.affiliation: LabTAU, Inserm U1032, Institut National de la Santé et de la Recherche Médicale, Lyon, France; Université Claude Bernard Lyon 1, Lyon, France.
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Chapelon
authors.affiliation: LabTAU, Inserm U1032, Institut National de la Santé et de la Recherche Médicale, Lyon, France; Université Claude Bernard Lyon 1, Lyon, France.
authors.forename: David
authors.initials: D
authors.lastname: Melodelima
mesh_terms: D000818:Animals; D057086:High-Intensity Focused Ultrasound Ablation; D007090:Image Interpretation, Computer-Assisted; D007432:Intraoperative Period; D008099:Liver / Q000502:physiology / Q000601:surgery*; D009068:Movement; D025321:Surgery, Computer-Assisted; D034421:Sus scrofa; D016896:Treatment Outcome