Measurement of the Skin-Liver Capsule Distance on Ultrasound RF Data for 1D Transient Elastography

Audière, Stéphane; Charbit, Maurice; Angelini, Elsa D.; Oudry, Jennifer; Sandrin, Laurent

doi:10.1007/978-3-642-15745-5_5

Cited by 5 publications

(5 citation statements)

References 13 publications

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“…The thick layer of subcutaneous adiposity can account at least partially for the association between CAP and BMI. A previous study using the M probe also showed an independent association between BMI and CAP which still persisted in patients with steatosis less than 5% [18]. Overall, these data suggest the contribution of subcutaneous adipose tissue to CAP overestimation in patients with morbid obesity.…”

Section: Discussionsupporting

confidence: 64%

Adaptation of controlled attenuation parameter (CAP) measurement depth in morbidly obese patients addressed for bariatric surgery

et al. 2019

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Background and aim The controlled attenuation parameter (CAP) using FibroScan (Echosens, Paris, France) M or XL probe has been developed for liver steatosis assessment. However, CAP performs poorly in patients with high body mass index. The aim of our study was to assess whether CAP is overestimated using the standard XL probe in patients with morbid obesity, and in the case of an overestimation, to reprocess the data at a greater depth to obtain the appropriate CAP (CAPa). Patients and methods We conducted an observational prospective cohort study on a total of 249 severely obese patients admitted to our institution to undergo sleeve gastrectomy. Patients had a liver biopsy performed during the surgery and a CAP measurement during the 15 days preceding biopsy. Patient files were reprocessed retrospectively by an algorithm, blinded to the patients’ clinical data. The algorithm automatically assessed the probe-to-capsula distance (PCD) by analysing the echogenicity of ultrasound signals on the time-motion mode. In the case of a distance >35 mm, the algorithm automatically selected a deeper measurement for CAP (CAPa). When PCD was less than 35 mm, the measured CAP was considered as appropriated (CAPa) and no further reprocessing was performed. Results CAP recording was not performed at a sufficient depth in 130 patients. In these patients, the CAPa obtained at the adapted depth was significantly lower than CAP (298±3.9 versus 340±4.2 dB/m; p< 0.0001) measured at the standard depth (35 to 75 mm). Multiple linear regression analysis revealed that both body mass index and hepatic steatosis were independently correlated with CAP values. After reprocessing the CAP in patients with PCD > 35 mm, steatosis stage was the only parameter independently correlated with CAP values. For the diagnosis of steatosis (S≥1), moderate to severe steatosis (S≥2) and severe steatosis (S = 3), the AUROC curves of CAPa (measured CAP in patients with PCD<35 mm and reprocessed CAP in those with PCD>35 mm) were 0.86, 0.83 and 0.79, respectively. The Obuchowski measure for the diagnosis of steatosis was 0.90±0.013. Conclusion CAP was overestimated in a half of morbidly obese patients using an XL probe, but CAP can be performed correctly in these patients after adapting the measurement depth.

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Section: Discussionsupporting

confidence: 64%

Adaptation of controlled attenuation parameter (CAP) measurement depth in morbidly obese patients addressed for bariatric surgery

et al. 2019

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“…3 for three of the parameters, these images showed high spatial variations of the parameter values and poor homogeneity within the three tissue layers: subcutaneous fat, muscle/fat layer and liver. Segmentation of these layers might be worthwhile to investigate via three approaches: (1) thresholding of the RF envelope, which is limited by a high noise level and uncalibrated variations on the RF envelope intensity, (2) thresholding of the spectral variance, confirming the results reported in [12], (3) exploitation of the SPI converging to zero at specular interfaces between the three layers, as clearly observed in Fig. 3.…”

Section: Spectral Parametric Images For Tissue Segmentationsupporting

confidence: 75%

Evaluation of in vivo Liver Tissue Characterization with Spectral RF Analysis versus Elasticity

Audière

Angelini

Charbit

et al. 2011

Lecture Notes in Computer Science

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Abstract. Ultrasonic elastography, via vibration-controlled transient elastography (VCTE™), enables to assess, under active mechanical constraints, the elasticity of the liver, correlating with fibrosis stages. On the other hand, the same VCTE™ probe can also be used in passive mode, acquiring RF lines at different locations in the liver. This paper presents a thorough evaluation of passivemode RF spectral parameters (integrated backscatter coefficient, power spectral index, effective scattering size and spectral variance), for tissue characterization on a large cohort of volunteers with various ranges of elasticity measures. Results showed that capabilities to discriminate between liver and subcutaneous fat tissues were highly variable among spectral parameters. Furthermore, it appears that no in vivo discrimination of liver elasticity/fibrosis stage can be performed with passive RF spectral analysis, at 3.5MHz.

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“…The SCD includes the layers of tissues connecting the epidermis of the skin to the liver, and can contain various proportions of fatty tissue. A fixed‐position FibroScan‐502 with M probe was used, and a series of temporal ultrasound radiofrequency lines were acquired to measure the subcutaneous layer thickness (<25 mm and ≥25 mm), which was subsequently separated from the liver tissue using real‐time computation during TE scanning . The value was based on the first measurement.…”

Section: Methodsmentioning

confidence: 99%

“…The layers of tissues that connect the skin to the liver capsule were defined as the skin capsular distance (SCD), and these layers are mainly comprised of subcutaneous fatty tissue. SCD may contribute to the beam distortion and scattering that is known to attenuate the propagation of shear waves into the liver and ultrasonic signals used to assess the speed of propagation . In patients with SCD thicker than 25 mm, the attenuation may be enhanced and lead to an overestimation of LSM, and the failure rate of the M probe was markedly increased to 33% .…”

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Impact of skin capsular distance on the performance of controlled attenuation parameter in patients with chronic liver disease

Shen

Zheng²,

Shi

et al. 2015

Liver International

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Background & AimsControlled attenuation parameter (CAP) is a non‐invasive method for evaluating hepatic steatosis. However, larger skin capsular distance (SCD) can affect the accuracy. The aim of this study was to investigate the impact of SCD on the diagnostic performance of CAP and liver stiffness measurement (LSM).MethodsOf 101 patients with non‐alcoholic fatty liver disease (NAFLD) and 280 patients with chronic hepatitis B (CHB) who underwent liver biopsy were prospectively recruited. CAP, LSM and SCD were performed using FibroScan with M probe. The areas under receiver operating characteristics curves (AUROCs) were calculated to determine the diagnostic efficacy. The optimal thresholds were defined by the maximum Youden index.Results SCD (B 30.34, P < 0.001) and hepatic steatosis (B 23.04, P < 0.001) were independently associated with CAP by multivariate analysis. The AUROCs were slightly higher for SCD <25 mm compared to those for SCD ≥25 mm for steatosis ≥5% (0.88 vs. 0.81), >33% (0.90 vs. 0.85) and >66% (0.84 vs. 0.72). For SCD <25 mm, the optimal CAP cut‐offs for differentiating steatosis ≥5%, >33% and >66% were 255.0 dB/m, 283.5 dB/m and 293.5 dB/m. However, cut‐offs were elevated by approximately 60–70 dB/m for SCD ≥25 mm. When stratified by fibrosis grade, LSM was significantly affected by SCD ≥25 mm for advanced fibrosis (≥F3) in NAFLD, but not in CHB.Conclusion CAP is a promising tool for detecting and quantifying hepatic steatosis. SCD ≥25 mm may cause overestimation of steatosis. Similarly, SCD ≥25 mm affects the detection of advanced fibrosis by LSM in NAFLD patients.

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Measurement of the Skin-Liver Capsule Distance on Ultrasound RF Data for 1D Transient Elastography

Cited by 5 publications

References 13 publications

Adaptation of controlled attenuation parameter (CAP) measurement depth in morbidly obese patients addressed for bariatric surgery

Adaptation of controlled attenuation parameter (CAP) measurement depth in morbidly obese patients addressed for bariatric surgery

Evaluation of in vivo Liver Tissue Characterization with Spectral RF Analysis versus Elasticity

Impact of skin capsular distance on the performance of controlled attenuation parameter in patients with chronic liver disease

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