Journal Article

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

Lamouri, Karima, Perlemuter, Gabriel, Balian, Axel, Somda, Sosthene, Dagher, Ibrahim, Tranchart, Hadrien, Voican, Cosmin Sebastian, Prevot, Sophie, Lebrun, Amandine, Njike-Nakseu, Micheline, Gaillard, Martin, Lainas, Panagiotis, Naveau, Sylvie

2019

Overview

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). 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. 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. 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.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Accuracy / Adult / Algorithms / Analysis / Attenuation / Bariatric surgery / Bariatric Surgery - methods / Biology and Life Sciences / Biopsy / Body mass / Body mass index / Body size / Diagnosis / Elasticity Imaging Techniques - methods / Fatty liver / Female / Gastrectomy / Gastrointestinal surgery / Health aspects / Hepatology / Human health and pathology / Humans / Hépatology and Gastroenterology / Life Sciences / Liver / Liver diseases / Male / Medical diagnosis / Medicine and Health Sciences / Mortality / Non-alcoholic Fatty Liver Disease - complications / Non-alcoholic Fatty Liver Disease - diagnostic imaging / Non-alcoholic Fatty Liver Disease - pathology / Non-alcoholic Fatty Liver Disease - surgery / Nutrition / Obesity / Obesity, Morbid - complications / Obesity, Morbid - diagnostic imaging / Obesity, Morbid - pathology / Obesity, Morbid - surgery / Overweight persons / Parameters / Patients / Predictive Value of Tests / Prevalence studies (Epidemiology) / Prospective Studies / Recording / Regression analysis / Reprocessing / Retrospective Studies / Risk factors / Steatosis / Surgery / Ultrasonic imaging / Ultrasound