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Influence of Probe Pressure on Ultrasound-Based Shear Wave Elastography of the Liver Using Comb-Push 2-D Technology
Umeå University, Faculty of Medicine, Department of Nursing.ORCID iD: 0000-0001-9338-1639
Umeå University, Faculty of Medicine, Department of Nursing.ORCID iD: 0000-0002-1248-5581
2019 (English)In: Ultrasound in Medicine and Biology, ISSN 0301-5629, E-ISSN 1879-291X, Vol. 45, no 2, p. 411-428Article in journal (Refereed) Published
Abstract [en]

It has been postulated that in the liver, applying increased probe pressure during ultrasound-based shear wave elastography (SWE) might lead to a false increase in the SWE result. We aimed to determine the influence of increased intercostal probe pressure when performing SWE of the liver. We also investigated the number of measurements required to achieve technically successful and reliable SWE examinations. This prospective, clinical study included 112 patients and 2240 SWE measurements of the liver. We applied probe pressure intercostally, to reduce the skin-to-liver capsule distance (SCD), which could stabilize the SWE signal and thus increase the number of technically successful measurements. We performed 10 measurements with maximum probe pressure and 10 with normal pressure in each patient. Thus, two analysis groups were compared for differences. Compared with normal pressure, maximum probe pressure significantly reduced the SCD (p < 0.001) and significantly increased the number of technically successful measurements from 981 to 1098, respectively (p < 0.001). The SWE results with normal and maximum probe pressure were 5.96 kPa (interquartile range: 2.41) and 5.45 kPa (interquartile range: 1.96), respectively (p < 0.001). In obese patients, a large SCD poses a diagnostic challenge for ultrasound SWE. We found that maximum intercostal probe pressure could reduce the SCD and increase the number of technically successful measurements, without falsely increasing the SWE result. Only three measurements were required to achieve technically successful and reliable SWE examinations.

Place, publisher, year, edition, pages
Elsevier, 2019. Vol. 45, no 2, p. 411-428
Keywords [en]
Shear wave elastography, Skin-to-liver capsule distance, Probe pressure, Measurements, Obesity, Pre-compressive force, Applied transducer force, Subcutaneous fat, Steatosis
National Category
Radiology, Nuclear Medicine and Medical Imaging Nursing
Research subject
Radiology; Radiography
Identifiers
URN: urn:nbn:se:umu:diva-153992DOI: 10.1016/j.ultrasmedbio.2018.09.023ISI: 000454875400012PubMedID: 30401508Scopus ID: 2-s2.0-85055907154OAI: oai:DiVA.org:umu-153992DiVA, id: diva2:1269704
Available from: 2018-12-11 Created: 2018-12-11 Last updated: 2020-03-29Bibliographically approved
In thesis
1. Ultrasound based shear wave elastography of the liver: a non-invasive method for evaluation of liver disease
Open this publication in new window or tab >>Ultrasound based shear wave elastography of the liver: a non-invasive method for evaluation of liver disease
2020 (English)Doctoral thesis, comprehensive summary (Other academic)
Alternative title[sv]
Ultraljudsbaserad shear wave elastografi av levern : en icke-invasiv metod för utvärdering av leversjukdom
Abstract [en]

Background: Detecting liver disease at an early stage is important, given that early intervention decreases the risk of developing cirrhosis and subsequently hepatocellular cancer (HCC). The non-invasive ultrasound-based shear wave elastography (SWE) has been used clinically for a decade to assess liver stiffness. This method is reliable, rapid and can be performed in an outpatient setting without known risks for the patient. However, increased variance in SWE results has been detected, without clear explanation. Factors that affect SWE results needs to be identified. Data are insufficient regarding the reliability of SWE with different body positions and probe pressures. Men have higher SWE results than women, also for unclear reasons. Increasing the reliability of SWE is crucial for understanding how factors such as overweight and obesity, cardiovascular and antiviral medication, age, sex, smoking habits, hepatic steatosis and cirrhosis affect SWE results.

Aims: The overall aim of the studies included in this thesis was to increase the reliability of SWE liver. The specific aims were to investigate patient-related factors associated with increased uncertainty in SWE results. Another aim was to investigate the influence of increased intercostal probe pressure on liver stiffness assessment with SWE liver.  The final aims were to investigate the influence of postural changes, sagittal abdominal diameter (SAD) and skin-to-liver capsule distance (SCD) on SWE results, along with sex-based differences for SWE results and cardiovascular medication.

Methods: All enrolled participants in these studies were consecutive patients with various liver diseases presenting at the radiology department Östersunds Hospital. The patients were examined using SWE liver method at the ultrasound unit between April 2014 and May 2018. Inclusion criteria were that participants be adults (age ≥18 years) who had provided written consent for participating in the study. The exclusion criterion was an inability to communicate. Current guidelines for SWE of the liver were used in the thesis with the following exceptions: In study II, increased intercostal probe pressure was used, and in study III, postural change was used. Study I included 188 patients; study II included 112 patients, and studies III and IV involved 200 patients. The four studies were conducted as cross-sectional and clinical trial, using quantitative methods.

Results: Factors associated with low variance for SWE results were age, sex, and presence of cirrhosis, the use of antiviral and/or cardiovascular medication, smoking habits, and body mass index.  Factors associated with increased uncertainty in SWE results were increased SCD and the presence of steatosis. With increased probe pressure SCD decreased and the quality of shear wave increased. The results showed that the number of required measurements can be reduced. A postural change to left decubitus decreased SCD. For patients with increased SAD and increased SWE result in the supine position, SWE result decreased with a postural change to left decubitus.  The SWE results, SCD and SAD significantly differed between women and men. SWE results was higher in the presence of increased SAD (≥23 cm) among men, but not among women.

Conclusions:  SWE of the liver is a reliable, non-invasive method for diagnosing liver disease. Results in this thesis suggest that for patients with SCD ≥2.5 cm, shear wave measures could be of poor quality and the SWE exam less reliable. In these cases, increased probe pressure may facilitate a reliable SWE exam. With such adjustments in probe pressure, the ultrasound-based SWE method can be superior for examination in patients with overweight or obesity. An effect of SAD ≥23 cm was seen for men with liver fibrosis only, which may explain the higher SWE result for men compared to women. Depending on the severity of liver disease and SAD, a postural change to left decubitus can produce a different outcome. As SAD increased, liver stiffness did, as well. Increased SAD thus is linked to increased liver stiffness, indicating that SAD should be taken into account when performing SWE of the liver.

Place, publisher, year, edition, pages
Umeå: Umeå University, 2020. p. 76
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 2070
Keywords
Anthropometric measurement, diagnostic imaging, elasticity imaging technique, blood supply, BMI, body position, fatty liver, liver disease, hepatic steatosis, liver fibrosis, liver stiffness, obesity, postural change, pressure, probe, sex characteristic, shear wave elastography, skin-to-liver capsule distance, transducer and ultrasonography
National Category
Radiology, Nuclear Medicine and Medical Imaging Gastroenterology and Hepatology Infectious Medicine
Research subject
Radiography
Identifiers
urn:nbn:se:umu:diva-167861 (URN)978-91-7855-197-2 (ISBN)978-91-7855-198-9 (ISBN)
Public defence
2020-04-24, Östersunds sjukhus, Hörsalen Snäckan, Östersund, 09:00 (Swedish)
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Supervisors
Note

Elektroniskt ISBN saknas i publikationen. 

Available from: 2020-04-03 Created: 2020-03-29 Last updated: 2020-04-08Bibliographically approved

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Byenfeldt, MarieFransson, Per

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