Prospective Study
Copyright ©The Author(s) 2015. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Jul 21, 2015; 21(27): 8425-8432
Published online Jul 21, 2015. doi: 10.3748/wjg.v21.i27.8425
Parameters affecting different acoustic radiation force impulse applications in the diagnosis of fibrotic liver changes
Sabrina Galgenmueller, Heike Jaeger, Wolfgang Kratzer, Stefan A Schmidt, Suemeyra Oeztuerk, Mark M Haenle, Richard A Mason, Tilmann Graeter
Sabrina Galgenmueller, Wolfgang Kratzer, Suemeyra Oeztuerk, Mark M Haenle, Department of Internal Medicine I, University Hospital Ulm, 89081 Ulm, Germany
Heike Jaeger, FASCIA Research, Division of Neurophysiology, 89081 Ulm, Germany
Stefan A Schmidt, Tilmann Graeter, Department of Diagnostic and Interventional Radiology, University Hospital Ulm, 89081 Ulm, Germany
Richard A Mason, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH 44106, United States
Author contributions: Galgenmueller S and Jaeger H contributed equally to this work; Kratzer W, Graeter T, Haenle MM, and Oeztuerk S designed the study; Galgenmueller S, Kratzer W, Graeter T, Haenle MM, Jaeger H, and Schmidt SA performed the research; Oeztuerk S analyzed the data; Galgenmueller S, Kratzer W, Mason RA, and Graeter T wrote the manuscript.
Institutional review board statement: The study was reviewed and approved by the local ethics committee of the University of Ulm.
Informed consent statement: Because of the retrospective and anonymous character of this study, the need for informed consent was waived by the institutional review board.
Conflict-of-interest statement: The authors declare that are no conflicts of interest.
Data sharing statement: No additional data are available.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Wolfgang Kratzer, Professor, Department of Internal Medicine I, University Hospital Ulm, Albert-Einstein-Allee 23, 89081 Ulm, Germany. wolfgang.kratzer@uniklinik-ulm.de
Telephone: +49-731-50044730 Fax: +49-731-50044620
Received: January 29, 2015
Peer-review started: February 10, 2015
First decision: March 10, 2015
Revised: March 17, 2015
Accepted: April 17, 2015
Article in press: April 17, 2015
Published online: July 21, 2015
Abstract

AIM: To analyze the virtual touch tissue quantification (VTTQ) and virtual touch imaging quantification (VTIQ) techniques, and identify possible factors that may influence VTTQ and VTIQ measurements.

METHODS: One hundred and eighty-six (104 women/82 men) of 323 subjects met the inclusion criteria (age > 18 years, no history of chronic or gastrointestinal disease, body-mass index (BMI) < 30 kg/m², a fasting period of at least three hours, no history of hepatotoxic pharmaceuticals, alcohol consumption < 24 g/d in men and < 12 g/d in women, and normal findings upon ultrasound examination of the abdomen). Measurements were taken at depths of 50 mm with VTTQ, 15 mm and 25 mm with VTIQ in the right hepatic lobe, and at 15 mm with only VTIQ in the left hepatic lobe. The examiner acquired six measurements per position, thereby giving 24 measurements in total.

RESULTS: The 95% confidence intervals of mean were 1.23-1.29 m/s for VTTQ and 1.29-1.37 m/s, 1.17-1.23 m/s, and 1.48-1.57 m/s for VTIQ in a depth of 15 mm and 25 mm in the right hepatic lobe and 15 mm in the left hepatic lobe. Only superficial measurements in the right hepatic lobe with the VTIQ method exhibited an effect of age on shear wave velocity. Measurements acquired using the 6C1 probe with the VTTQ method showed no dependence on BMI. By comparison, BMI influenced measurements taken with the VTIQ method using the 9L4 probe in the superficial and deep areas of the right hepatic lobe, as well as in the left hepatic lobe (P = 0.0160, P = 0.0019, P = 0.0173, respectively). Gender influenced measurements at depths of 50 mm with VTTQ and 25 mm with VTIQ in the right hepatic lobe (P = 0.0001, P = 0.0269). Significant differences were found between measurements with the 6C1 (VTTQ) and 9L4 probes (VTIQ) (P = 0.0067), between superficial and deep measurements (P < 0.0001), and between the right and left lobes of the liver (P < 0.0001).

CONCLUSION: Measurements in the right lobe and deep regions are preferable. Gender differences must be considered. BMI must be considered when assessing VTIQ technology.

Keywords: Acoustic radiation force impulse, Elasticity imaging techniques, Liver, Reference standards, Virtual touch imaging and quantification, Virtual touch tissue quantification, Ultrasonography

Core tip: Virtual touch tissue quantification (VTTQ) and virtual touch imaging and quantification (VTIQ) are two new elastographic techniques for estimating tissue stiffness. Both methods (VTTQ and VTIQ) allow a quantitative and non-invasive assessment of shear wave velocity. Shear wave speed quantification may be a diagnostic tool in the diagnosis of fibrotic liver changes. Therefore, standard values in healthy liver tissue must be generated. The objective of the present study is to analyze the VTTQ and VTIQ techniques. Possible factors that may influence VTTQ and VTIQ measurements were also studied.