Electrode displacement strain imaging of thermally-ablated liver tissue in an in vivo animal model.
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.
Rubert
N
N
Department of Medical Physics, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, Wisconsin 53706, USA.
Bharat
S
S
DeWall
R J
RJ
Andreano
A
A
Brace
C
C
Jiang
J
J
Sampson
L
L
Varghese
T
T
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*
AJR Am J Roentgenol. 2003 Sep;181(3):701-7
12933463
Radiology. 1997 Nov;205(2):367-73
9356616
Ultrasound Med Biol. 2002 Nov-Dec;28(11-12):1467-73
12498942
Med Phys. 2008 Sep;35(9):4132-41
18841866
Phys Med Biol. 2006 Dec 21;51(24):6403-18
17148825
Ann Surg. 2004 Jan;239(1):53-60
14685100
Magn Reson Med. 2001 Jan;45(1):80-7
11146489
Ultrasound Med Biol. 2001 Aug;27(8):1099-106
11527596
J Ultrasound Med. 2008 Jun;27(6):935-46
18499853
Ultrasound Med Biol. 2008 Feb;34(2):276-88
17935863
Minim Invasive Ther Allied Technol. 2006;15(1):9-17
16687327
AJR Am J Roentgenol. 2007 Feb;188(2):480-8
17242258
Eur Radiol. 2007 Sep;17(9):2401-10
17701184
Oncology. 2007;72 Suppl 1:124-31
18087193
Int J Radiat Oncol Biol Phys. 1984 Jun;10(6):787-800
6547421
Med Phys. 2008 Jun;35(6):2432-42
18649476
Eur J Ultrasound. 2001 Jun;13(2):149-58
11369526
Ultrasound Med Biol. 2008 Oct;34(10):1590-603
18471954
Phys Med Biol. 2007 Jan 21;52(2):389-401
17202622
Ultrasound Med Biol. 2008 Aug;34(8):1307-16
18374467
J Vasc Interv Radiol. 2009 Apr;20(4):490-9
19328427
Eur J Ultrasound. 2001 Jun;13(2):117-27
11369524
IEEE Trans Ultrason Ferroelectr Freq Control. 2005 Apr;52(4):631-41
16060512
AJR Am J Roentgenol. 2000 Feb;174(2):323-31
10658699
CA Cancer J Clin. 2008 Mar-Apr;58(2):71-96
18287387
Crit Rev Oncol Hematol. 2008 Jun;66(3):200-7
18304832
Radiology. 1997 Jan;202(1):195-203
8988211
IEEE Trans Ultrason Ferroelectr Freq Control. 2007 Feb;54(2):281-9
17328325
Ultrasound Med Biol. 1999 Sep;25(7):1099-113
10574342