Observational Study
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World J Gastroenterol. Sep 7, 2014; 20(33): 11850-11855
Published online Sep 7, 2014. doi: 10.3748/wjg.v20.i33.11850
Radiologic-pathologic correlation of three-dimensional shear-wave elastographic findings in assessing the liver ablation volume after radiofrequency ablation
Katsutoshi Sugimoto, Hisashi Oshiro, Saori Ogawa, Mitsuyoshi Honjo, Takeshi Hara, Fuminori Moriyasu
Katsutoshi Sugimoto, Fuminori Moriyasu, Department of Gastroenterology and Hepatology, Tokyo Medical University, Tokyo 160-0023, Japan
Hisashi Oshiro, Saori Ogawa, Mitsuyoshi Honjo, Department of Pathology, Tokyo Medical University, Tokyo 160-0023, Japan
Takeshi Hara, Department of Intelligent Image Information, Gifu University Graduate School of Medicine, Gifu 501-1193, Japan
Author contributions: Sugimoto K and Moriyasu F designed the study; Sugimoto K, Oshiro H, Ogawa S and Honjo M performed the research; Hara T contributed the analytic tools; Sugimoto K and Moriyasu F analyzed the data; and Sugimoto K and Oshiro H wrote the paper.
Correspondence to: Katsutoshi Sugimoto, MD, Department of Gastroenterology and Hepatology, Tokyo Medical University, 6-7-1 Nishishinjuku, Shinjuku-ku, Tokyo 160-0023, Japan. sugimoto@tokyo-med.ac.jp
Telephone: +81-3-33426111  Fax: +81-3-53816654
Received: February 13, 2014
Revised: April 24, 2014
Accepted: May 29, 2014
Published online: September 7, 2014
Processing time: 205 Days and 21.3 Hours
Abstract

AIM: To evaluate the usefulness of three-dimensional (3D) shear-wave elastography (SWE) in assessing the liver ablation volume after radiofrequency (RF) ablation.

METHODS: RF ablation was performed in vivo in 10 rat livers using a 15-gauge expandable RF needle. 3D SWE as well as B-mode ultrasound (US) were performed 15 min after ablation. The acquired 3D volume data were rendered as multislice images (interslice distance: 1.10 mm), and the estimated ablation volumes were calculated. The 3D SWE findings were compared against digitized photographs of gross pathological and histopathological specimens of the livers obtained in the same sectional planes as the 3D SWE multislice images. The ablation volumes were also estimated by gross pathological examination of the livers, and the results were then compared with those obtained by 3D SWE.

RESULTS: In B-mode US images, the ablation zone appeared as a hypoechoic area with a peripheral hyperechoic rim; however, the findings were too indistinct to be useful for estimating the ablation area. 3D SWE depicted the ablation area and volume more clearly. In the images showing the largest ablation area, the mean kPa values of the peripheral rim, central zone, and non-ablated zone were 13.1 ± 1.5 kPa, 59.1 ± 21.9 kPa, and 4.3 ± 0.8 kPa, respectively. The ablation volumes depicted by 3D SWE correlated well with those estimated from gross pathological examination (r2 = 0.9305, P = 0.00001). The congestion and diapedesis of red blood cells observed in histopathological examination were greater in the peripheral rim of the ablation zone than in the central zone.

CONCLUSION: 3D SWE outperforms B-mode US in delineating ablated areas in the liver and is therefore more reliable for spatially delineating thermal lesions created by RF ablation.

Keywords: Radiofrequency ablation; Liver; Ultrasound; Shear-wave elastography; Three-dimensional

Core tip: Three-dimensional shear-wave elastography is a reliable noninvasive technique that may be useful for the real-time assessment of treatment efficacy immediately after radiofrequency ablation procedures. It is superior to B-mode ultrasound in delineating the ablated areas in the liver. The threshold value for determining remaining cell viability was found to be 13.1 ± 1.5 kPa.