title: Assessment of acute thermal damage volumes in muscle using magnetization-prepared 3D T2-weighted imaging following MRI-guided high-intensity focused ultrasound therapy.
abstract: To evaluate magnetization-prepared 3D T2-weighted magnetic resonance imaging (MRI) measurements of acute tissue changes produced during ablative MR high-intensity focused ultrasound (MR-HIFU) exposures.
  
  
  
  A clinical MR-HIFU system (3T) was used to generate thermal lesions (n = 24) in the skeletal muscles of three pigs. T1-weighted, 2D T2-weighted, and magnetization-prepared 3D T2-weighted sequences were acquired before and after therapy to evaluate tissue changes following ablation. Tissues were harvested shortly after imaging, fixed in formalin, and gross-sectioned. Select lesions were processed into whole-mount sections. Lesion dimensions for each imaging sequence (length, width) and for gross sections (diameter of lesion core and rim) were assessed by three physicists. Contrast-to-background ratio between lesions and surrounding muscle was compared.
  
  
  
  Lesion dimensions on T1and 2D T2-weighted imaging sequences were well correlated (R2∼0.7). The contrast-to-background ratio between lesion and surrounding muscle was 7.4 ± 2.4 for the magnetization-prepared sequence versus 1.7 ± 0.5 for a conventional 2D T2-weighted acquisition, and 7.0 ± 2.9 for a contrast-enhanced T1-weighted sequence. Compared with diameter measured on gross pathology, all imaging sequences overestimated the lesion core by 22-33%, and underestimated the lesion rim by 6-13%.
  
  
  
  After MR-HIFU exposures, measurements of the acute thermal damage patterns in muscle using a magnetization-prepared 3D T2-weighted imaging sequence correlate with 2D T2-weighted and contrast-enhanced T1-weighted imaging, and all agree well with histology. The magnetization-prepared sequence offers positive tissue contrast and does not require IV contrast agents, and may provide a noninvasive imaging evaluation of the region of acute thermal injury at multiple times during HIFU procedures.
  
  
  
  1 Technical Efficacy: Stage 2 J. MAGN. RESON. IMAGING 2017;46:354-364.
authors.affiliation: Department of Radiology, UT Southwestern Medical Center, Dallas, Texas, USA.|Clinical Sites Research Program, Philips Research North America, Cambridge, Massachusetts, USA.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Staruch
authors.affiliation: Department of Radiology, UT Southwestern Medical Center, Dallas, Texas, USA.
authors.forename: Joris
authors.initials: J
authors.lastname: Nofiele
authors.affiliation: Department of Pathology, UT Southwestern Medical Center, Dallas, Texas, USA.
authors.forename: Jamie
authors.initials: J
authors.lastname: Walker
authors.affiliation: Department of Radiology, UT Southwestern Medical Center, Dallas, Texas, USA.
authors.forename: Chenchen
authors.initials: C
authors.lastname: Bing
authors.affiliation: Department of Radiology, UT Southwestern Medical Center, Dallas, Texas, USA.|Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, Texas, USA.
authors.forename: Ananth J
authors.initials: AJ
authors.lastname: Madhuranthakam
authors.affiliation: Department of Radiology, UT Southwestern Medical Center, Dallas, Texas, USA.
authors.forename: April
authors.initials: A
authors.lastname: Bailey
authors.affiliation: Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University, Seoul, Korea.
authors.forename: Young-Sun
authors.initials: YS
authors.lastname: Kim
authors.affiliation: Department of Radiology, UT Southwestern Medical Center, Dallas, Texas, USA.
authors.forename: Avneesh
authors.initials: A
authors.lastname: Chhabra
authors.affiliation: Department of Pathology, UT Southwestern Medical Center, Dallas, Texas, USA.
authors.forename: Dennis
authors.initials: D
authors.lastname: Burns
authors.affiliation: Department of Radiology, UT Southwestern Medical Center, Dallas, Texas, USA.|Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, Texas, USA.
authors.forename: Rajiv
authors.initials: R
authors.lastname: Chopra
mesh_terms: D000818:Animals; D002404:Catheterization; D003287:Contrast Media; D000074059:Extracorporeal Shockwave Therapy; D005260:Female; D006358:Hot Temperature; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging*; D009336:Necrosis; D010100:Oxygen; D059629:Signal-To-Noise Ratio; D013552:Swine
chemical_list: D003287:Contrast Media; D010100:Oxygen
keywords: HIFU; MRI; high-intensity focused ultrasound; preclinical; thermal ablation