title: Electrode displacement strain imaging of thermally-ablated liver tissue in an in vivo animal model.
abstract: OBJECTIVE
  Percutaneous thermal ablation is increasingly being used to destroy hepatic tumors in situ. The success of ablative techniques is highly dependent on adequate ablation zone monitoring, and ultrasound-based strain imaging could become a convenient and cost-effective means to delineate ablation zone boundaries. This study investigates in vivo electrode displacement-based strain imaging for monitoring hepatic ablation procedures that are difficult to perform with conventional elastography.
  
  
  METHODS
  a In our method, minute displacements (less than a millimeter) are applied to the unconstrained end of the ablation electrode, resulting in localized tissue deformation within the ablation zone that provides the mechanical stimuli required for strain imaging. This article presents electrode displacement strain images of radiofrequency ablation zones created in porcine liver in vivo (n = 13).
  
  
  RESULTS
  Cross-sectional area measurements from strain images of these ablation zones were obtained using manual and automated segmentation. Area measurements from strain images were highly correlated with areas measured on histopathology images, quantitated using linear regression (R = 0.894, P < 0.001 and R = 0.828, P < 0.001, respectively).
  
  
  CONCLUSIONS
  This study further demonstrates that electrode displacement elastography is capable of providing high-contrast images using widely available commercial ultrasound systems which may potentially be used to assess the extent of thermal ablation zones.
authors.affiliation: Department of Medical Physics, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, Wisconsin 53706, USA.
authors.forename: N
authors.initials: N
authors.lastname: Rubert
authors.forename: S
authors.initials: S
authors.lastname: Bharat
authors.forename: R J
authors.initials: RJ
authors.lastname: DeWall
authors.forename: A
authors.initials: A
authors.lastname: Andreano
authors.forename: C
authors.initials: C
authors.lastname: Brace
authors.forename: J
authors.initials: J
authors.lastname: Jiang
authors.forename: L
authors.initials: L
authors.lastname: Sampson
authors.forename: T
authors.initials: T
authors.lastname: Varghese
mesh_terms: D000818:Animals; D017115:Catheter Ablation / Q000295:instrumentation / Q000379:methods*; D054459:Elasticity Imaging Techniques / Q000379:methods*; D004566:Electrodes; D006498:Hepatectomy / Q000379:methods*; D006801:Humans; D008099:Liver / Q000000981:diagnostic imaging* / Q000601:surgery*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D025321:Surgery, Computer-Assisted / Q000295:instrumentation / Q000379:methods*; D013552:Swine; D014463:Ultrasonography / Q000379:methods*
references.citation: AJR Am J Roentgenol. 2003 Sep;181(3):701-7
references.pmid: 12933463
references.citation: Radiology. 1997 Nov;205(2):367-73
references.pmid: 9356616
references.citation: Ultrasound Med Biol. 2002 Nov-Dec;28(11-12):1467-73
references.pmid: 12498942
references.citation: Med Phys. 2008 Sep;35(9):4132-41
references.pmid: 18841866
references.citation: Phys Med Biol. 2006 Dec 21;51(24):6403-18
references.pmid: 17148825
references.citation: Ann Surg. 2004 Jan;239(1):53-60
references.pmid: 14685100
references.citation: Magn Reson Med. 2001 Jan;45(1):80-7
references.pmid: 11146489
references.citation: Ultrasound Med Biol. 2001 Aug;27(8):1099-106
references.pmid: 11527596
references.citation: J Ultrasound Med. 2008 Jun;27(6):935-46
references.pmid: 18499853
references.citation: Ultrasound Med Biol. 2008 Feb;34(2):276-88
references.pmid: 17935863
references.citation: Minim Invasive Ther Allied Technol. 2006;15(1):9-17
references.pmid: 16687327
references.citation: AJR Am J Roentgenol. 2007 Feb;188(2):480-8
references.pmid: 17242258
references.citation: Eur Radiol. 2007 Sep;17(9):2401-10
references.pmid: 17701184
references.citation: Oncology. 2007;72 Suppl 1:124-31
references.pmid: 18087193
references.citation: Int J Radiat Oncol Biol Phys. 1984 Jun;10(6):787-800
references.pmid: 6547421
references.citation: Med Phys. 2008 Jun;35(6):2432-42
references.pmid: 18649476
references.citation: Eur J Ultrasound. 2001 Jun;13(2):149-58
references.pmid: 11369526
references.citation: Ultrasound Med Biol. 2008 Oct;34(10):1590-603
references.pmid: 18471954
references.citation: Phys Med Biol. 2007 Jan 21;52(2):389-401
references.pmid: 17202622
references.citation: Ultrasound Med Biol. 2008 Aug;34(8):1307-16
references.pmid: 18374467
references.citation: J Vasc Interv Radiol. 2009 Apr;20(4):490-9
references.pmid: 19328427
references.citation: Eur J Ultrasound. 2001 Jun;13(2):117-27
references.pmid: 11369524
references.citation: IEEE Trans Ultrason Ferroelectr Freq Control. 2005 Apr;52(4):631-41
references.pmid: 16060512
references.citation: AJR Am J Roentgenol. 2000 Feb;174(2):323-31
references.pmid: 10658699
references.citation: CA Cancer J Clin. 2008 Mar-Apr;58(2):71-96
references.pmid: 18287387
references.citation: Crit Rev Oncol Hematol. 2008 Jun;66(3):200-7
references.pmid: 18304832
references.citation: Radiology. 1997 Jan;202(1):195-203
references.pmid: 8988211
references.citation: IEEE Trans Ultrason Ferroelectr Freq Control. 2007 Feb;54(2):281-9
references.pmid: 17328325
references.citation: Ultrasound Med Biol. 1999 Sep;25(7):1099-113
references.pmid: 10574342