title: Magnetic resonance imaging assessment of effective ablated volume following high intensity focused ultrasound.
abstract: Under magnetic resonance (MR) guidance, high intensity focused ultrasound (HIFU) is capable of precise and accurate delivery of thermal dose to tissues. Given the excellent soft tissue imaging capabilities of MRI, but the lack of data on the correlation of MRI findings to histology following HIFU, we sought to examine tumor response to HIFU ablation to determine whether there was a correlation between histological findings and common MR imaging protocols in the assessment of the extent of thermal damage. Female FVB mice (n = 34), bearing bilateral neu deletion tumors, were unilaterally insonated under MR guidance, with the contralateral tumor as a control. Between one and five spots (focal size 0.5 × 0.5 × 2.5 mm3) were insonated per tumor with each spot receiving approximately 74.2 J of acoustic energy over a period of 7 seconds. Animals were then imaged on a 7T MR scanner with several protocols. T1 weighted images (with and without gadolinium contrast) were collected in addition to a series of T2 weighted and diffusion weighted images (for later reconstruction into T2 and apparent diffusion coefficient maps), immediately following ablation and at 6, 24, and 48 hours post treatment. Animals were sacrificed at each time point and both insonated/treated and contralateral tumors removed and stained for NADH-diaphorase, caspase 3, or with hematoxylin and eosin (H&E). We found the area of non-enhancement on contrast enhanced T1 weighted imaging immediately post ablation correlated with the region of tissue receiving a thermal dose CEM43 ≥ 240 min. Moreover, while both tumor T2 and apparent diffusion coefficient values changed from pre-ablation values, contrast enhanced T1 weighted images appeared to be more senstive to changes in tissue viability following HIFU ablation.
authors.affiliation: Department of Biomedical Engineering, University of California Davis, Davis, CA, 95616, United States of America.
authors.forename: Brett Z
authors.initials: BZ
authors.lastname: Fite
authors.affiliation: Department of Biomedical Engineering, University of California Davis, Davis, CA, 95616, United States of America.
authors.forename: Andrew
authors.initials: A
authors.lastname: Wong
authors.affiliation: Department of Biomedical Engineering, University of California Davis, Davis, CA, 95616, United States of America.
authors.forename: Yu
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Biomedical Engineering, University of California Davis, Davis, CA, 95616, United States of America.
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Mahakian
authors.affiliation: Department of Biomedical Engineering, University of California Davis, Davis, CA, 95616, United States of America.
authors.forename: Sarah M
authors.initials: SM
authors.lastname: Tam
authors.affiliation: Center for Comparative Medicine, University of California Davis, Davis, CA, 95616, United States of America.
authors.forename: Olulanu
authors.initials: O
authors.lastname: Aina
authors.affiliation: Center for Comparative Medicine, University of California Davis, Davis, CA, 95616, United States of America.
authors.forename: Neil E
authors.initials: NE
authors.lastname: Hubbard
authors.affiliation: Center for Comparative Medicine, University of California Davis, Davis, CA, 95616, United States of America; Department of Pathology and Laboratory Medicine, School of Medicine, University of California Davis, Davis, CA, 95616, United States of America.
authors.forename: Alexander
authors.initials: A
authors.lastname: Borowsky
authors.affiliation: Center for Comparative Medicine, University of California Davis, Davis, CA, 95616, United States of America; Department of Pathology and Laboratory Medicine, School of Medicine, University of California Davis, Davis, CA, 95616, United States of America.
authors.forename: Robert D
authors.initials: RD
authors.lastname: Cardiff
authors.affiliation: Image Guided Therapy, Pessac, France.
authors.forename: Erik
authors.initials: E
authors.lastname: Dumont
authors.affiliation: Department of Biomedical Engineering, University of California Davis, Davis, CA, 95616, United States of America.
authors.forename: Katherine W
authors.initials: KW
authors.lastname: Ferrara
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D000818:Animals; D045744:Cell Line, Tumor; D003287:Contrast Media / Q000737:chemistry / Q000378:metabolism; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D005682:Gadolinium / Q000737:chemistry / Q000378:metabolism; D057086:High-Intensity Focused Ultrasound Ablation / Q000295:instrumentation / Q000379:methods*; D006651:Histocytochemistry; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008325:Mammary Neoplasms, Experimental / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D051379:Mice; D013016:Sound; D025321:Surgery, Computer-Assisted; D047368:Tumor Burden / Q000528:radiation effects*
chemical_list: D003287:Contrast Media; D005682:Gadolinium