Korean J Radiol.  2019 Feb;20(2):225-235. 10.3348/kjr.2018.0320.

Usefulness of Virtual Expiratory CT Images to Compensate for Respiratory Liver Motion in Ultrasound/CT Image Fusion: A Prospective Study in Patients with Focal Hepatic Lesions

• Kang TW
• Lee MW
• Cha DI
• Park HJ
• Park JS
• Bang WC
• Kim SW

• KMID: 2438253
• DOI: http://doi.org/10.3348/kjr.2018.0320

Abstract

OBJECTIVE
To assess whether virtual expiratory (VE)-computed tomography (CT)/ultrasound (US) fusion imaging is more effective than conventional inspiratory (CI)-CT/US fusion imaging for hepatic interventional procedures.
MATERIALS AND METHODS
This prospective study was approved by the Institutional Review Board, and informed consent was obtained from each patient. In total, 62 patients with focal hepatic lesions referred for hepatic interventional procedures were enrolled. VE-CT images were generated from CI-CT images to reduce the effects of respiration-induced liver motion. The two types of CT images were fused with real-time US images for each patient. The operators scored the visual similarity with the liver anatomy upon initial image fusion and the summative usability of complete image fusion using the respective five-point scales. The time required for complete image fusion and the number of point locks used were also compared.
RESULTS
In comparison with CI-CT/US fusion imaging, VE-CT/US fusion imaging showed significantly higher visual similarity with the liver anatomy on the initial image fusion (mean score, 3.9 vs. 1.7; p < 0.001) and higher summative usability for complete image fusion (mean score, 4.0 vs. 1.9; p < 0.001). The required time (mean, 11.1 seconds vs. 22.5 seconds; p < 0.001) and the number of point locks (mean, 1.6 vs. 3.0; p < 0.001) needed for complete image fusion using VE-CT/US fusion imaging were significantly lower than those needed for CI-CT/US fusion imaging.
CONCLUSION
VE-CT/US fusion imaging is more effective than CI-CT/US fusion imaging for hepatic interventional procedures.

Keyword

Ultrasonography; Computed tomography; Fusion imaging; Liver; Respiration

MeSH Terms

Ethics Committees, Research
Humans
Informed Consent
Liver*
Prospective Studies*
Respiration
Ultrasonography
Weights and Measures

Figure

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  Fig. 1 Pilot study for technical feasibility of VE-CT images using CI-CT images.This is initial alignment of fusion imaging between CT and US images. To easily compare similarity of two images, VE-CT image was positioned on left side of US image and CI-CT image was positioned on right side of US image. Our simulation software (Blind Test Tool; Samsung Medison) shows that hepatic anatomy on US images at rest is more similar to VE-CT than CI-CT upon initial image fusion. Consequently, it is expected that point locks can be performed more easily with VE-CT by selecting right portal vein branch (arrows) for complete image fusion. CI = conventional inspiratory, CT = computed tomography, US = ultrasound, VE = virtual expiratory

• 

  Fig. 2 Study flow diagram.

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  Fig. 3 VE-CT generation using CI-CT and estimated liver motion.

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  Fig. 4 Process of image fusion and outcome evaluation.3D = three-dimensional

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  Fig. 5 Improved visual similarity after initial image fusion in VE-CT/US fusion imaging.A. 54-year-old-woman with hepatic metastasis from pancreatic cancer. On CI-CT/US fusion imaging before applying any point lock, anatomical relationship of right hepatic vein (white arrows) and right portal vein (black arrow) is quite different between real-time US images and CI-CT images. In CI-CT image, right portal vein is not visible due to misregistration. Total time elapsed for complete image fusion was 27 seconds. Scores for visual similarity and summative usability were 2 and 3, respectively. B. When using VE-CT images as reference dataset, hepatic vascular anatomy on real-time US image was quite similar to that on VE-CT image due to compensation of respiration-induced liver motion. Consequently, total time required for complete image fusion was only 6 seconds. In this case, VE-CT/US image fusion was performed first according to results of randomization. Scores for visual similarity and summative usability were 5 and 5, respectively. Right hepatic vein (white arrows) and right portal vein (black arrows).

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  Fig. 6 Improved summative usability for complete image fusion in VE-CT/US fusion imaging.A. 50-year-old-woman with multiple hepatic metastases from colon cancer. On CI-CT/US fusion imaging before applying any point lock, index T was invisible on CI-CT image upon initial registration. Therefore, two additional point locks were needed for complete image fusion. Total time required for complete image fusion was 10 seconds. Scores for visual similarity and summative usability were 2 and 2, respectively. B. On VE-CT/US fusion imaging before applying any point lock, index T was clearly visible at corresponding site and only one point lock was enough for fine registration. Total time required for complete image fusion was 4 seconds. In this case, VE-CT/US image fusion was performed first according to results of randomization. Scores for visual similarity and summative usability were 4 and 5, respectively. T = tumor

Reference

1. Yang M, Ding H, Kang J, Zhu L, Wang G. Subject-specific real-time respiratory liver motion compensation method for ultrasound-MRI/CT fusion imaging. Int J Comput Assist Radiol Surg. 2015; 10:517–529. PMID: 24927901.

2. Lee MW. Fusion imaging of real-time ultrasonography with CT or MRI for hepatic intervention. Ultrasonography. 2014; 33:227–239. PMID: 25036756.

3. Park HJ, Lee MW, Lee MH, Hwang J, Kang TW, Lim S, et al. Fusion imaging-guided percutaneous biopsy of focal hepatic lesions with poor conspicuity on conventional sonography. J Ultrasound Med. 2013; 32:1557–1564. PMID: 23980215.

4. Ahn SJ, Lee JM, Lee DH, Lee SM, Yoon JH, Kim YJ, et al. Real-time US-CT/MR fusion imaging for percutaneous radiofrequency ablation of hepatocellular carcinoma. J Hepatol. 2017; 66:347–354. PMID: 27650284.

5. Jung EM, Friedrich C, Hoffstetter P, Dendl LM, Klebl F, Agha A, et al. Volume navigation with contrast enhanced ultrasound and image fusion for percutaneous interventions: first results. PLoS One. 2012; 7:e33956. PMID: 22448281.

6. Lee DH, Lee JM. Recent advances in the image-guided tumor ablation of liver malignancies: radiofrequency ablation with multiple electrodes, real-time multimodality fusion imaging, and new energy sources. Korean J Radiol. 2018; 19:545–559. PMID: 29962861.

7. Kim JW, Shin SS, Heo SH, Hong JH, Lim HS, Seon HJ, et al. Ultrasound-guided percutaneous radiofrequency ablation of liver tumors: how we do it safely and completely. Korean J Radiol. 2015; 16:1226–1239. PMID: 26576111.

8. Paulsson AK, Yom SS, Anwar M, Pinnaduwage D, Sudhyadhom A, Gottschalk AR, et al. Respiration-induced intraorgan deformation of the liver. Technol Cancer Res Treat. 2017; 1533034616687193. PMID: 28071340.

9. Cha DI, Lee MW, Kang TW, Oh YT, Jeong JY, Chang JW, et al. Comparison between CT and MR images as more favorable reference data sets for fusion imaging-guided radiofrequency ablation or biopsy of hepatic lesions: a prospective study with focus on patient's respiration. Cardiovasc Intervent Radiol. 2017; 40:1567–1575. PMID: 28462444.

10. Rohlfing T, Maurer CR Jr, O'Dell WG, Zhong J. Modeling liver motion and deformation during the respiratory cycle using intensity-based nonrigid registration of gated MR images. Med Phys. 2004; 31:427–432. PMID: 15070239.

11. Lee MW, Park HJ, Kang TW, Ryu J, Bang WC, Lee B, et al. Image fusion of real-time ultrasonography with computed tomography: factors affecting the registration error and motion of focal hepatic lesions. Ultrasound Med Biol. 2017; 43:2024–2032. PMID: 28641911.

12. Mauri G, Cova L, De Beni S, Ierace T, Tondolo T, Cerri A, et al. Real-time US-CT/MRI image fusion for guidance of thermal ablation of liver tumors undetectable with US: results in 295 cases. Cardiovasc Intervent Radiol. 2015; 38:143–151. PMID: 24806953.

13. Kang TW, Rhim H, Lee MW, Kim W, Park JG. Predicting coverage of transverse subcostal sonography with the use of previous computed tomography before a sonographic liver examination: a prospective study. J Ultrasound Med. 2013; 32:2053–2061. PMID: 24277886.

14. Cha DI, Lee MW, Kim AY, Kang TW, Oh YT, Jeong JY, et al. Automatic image fusion of real-time ultrasound with computed tomography images: a prospective comparison between two auto-registration methods. Acta Radiol. 2017; 58:1349–1357. PMID: 28273740.

15. Cha DI, Lee MW, Song KD, Oh YT, Jeong JY, Chang JW, et al. A prospective comparison between auto-registration and manual registration of real-time ultrasound with MR images for percutaneous ablation or biopsy of hepatic lesions. Abdom Radiol (NY). 2017; 42:1799–1808. PMID: 28194514.

16. Bobin J, Starck JL, Fadili JM, Moudden Y, Donoho DL. Morphological component analysis: an adaptive thresholding strategy. IEEE Trans Image Process. 2007; 16:2675–2681. PMID: 17990744.

17. Che C, Mathai TS, Galeotti J. Ultrasound registration: a review. Methods. 2017; 115:128–143. PMID: 27965119.

18. Kang TW, Lee MW, Hye MJ, Song KD, Lim S, Rhim H, et al. Percutaneous radiofrequency ablation of hepatic tumours: factors affecting technical failure of artificial ascites formation using an angiosheath. Clin Radiol. 2014; 69:1249–1258. PMID: 25149600.

19. Yu JI, Kim JS, Park HC, Lim DH, Han YY, Lim HC, et al. Evaluation of anatomical landmark position differences between respiration-gated MRI and four-dimensional CT for radiation therapy in patients with hepatocellular carcinoma. Br J Radiol. 2013; 86:20120221. PMID: 23239694.

20. Ewertsen C, Săftoiu A, Gruionu LG, Karstrup S, Nielsen MB. Real-time image fusion involving diagnostic ultrasound. AJR Am J Roentgenol. 2013; 200:W249–W255. PMID: 23436869.

21. Suramo I, Päivänsalo M, Myllylä V. Cranio-caudal movements of the liver, pancreas and kidneys in respiration. Acta Radiol Diagn (Stockh). 1984; 25:129–113. PMID: 6731017.

22. Lim S, Lee MW, Rhim H, Cha DI, Kang TW, Min JH, et al. Mistargeting after fusion imaging-guided percutaneous radiofrequency ablation of hepatocellular carcinomas. J Vasc Interv Radiol. 2014; 25:307–314. PMID: 24315550.

23. Chung S, Kim KE, Park MS, Bhagavatula S, Babb J, Axel L. Liver stiffness assessment with tagged MRI of cardiac-induced liver motion in cirrhosis patients. J Magn Reson Imaging. 2014; 39:1301–1307. PMID: 24719241.

24. Brüggmann D, Tchartchian G, Wallwiener M, Münstedt K, Tinneberg HR, Hackethal A. Intra-abdominal adhesions: definition, origin, significance in surgical practice, and treatment options. Dtsch Arztebl Int. 2010; 107:769–775. PMID: 21116396.