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

Abstract

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.

Associations between Phase Angle Values Obtained by Bioelectrical Impedance Analysis and Nonalcoholic Fatty Liver Disease in an Overweight Population

“…Currently, because CAP has been reported to perform well for mild steatosis on people with NAFLD [16], the normal range was less than 240 dB/min and our study also tested CAP values. CAP was measured by the ultrasonic attenuation at 3.5 MHz using the FibroScan (EchoSens, Paris, France).…”

Prospective comparison of transient elastography, MRI and serum scores for grading steatosis and detecting non-alcoholic steatohepatitis in bariatric surgery candidates

“… 17 , 18 Regarding morbidly obese patients who are candidates to bariatric surgery, data are scarce so far. [19] , [20] , [21] , [22] , [23] MRI-based techniques, such as magnetic resonance elastography (MRE) and proton density fat fraction (PDFF) have been shown to accurately stage fibrosis and grade steatosis, respectively, in patients with NAFLD 13 and to outperform TE-CAP for fibrosis staging and steatosis quantification. 24 , 25 However, data in morbidly obese patients undergoing bariatric surgery remains limited.…”

Impact of Sleeve Gastrectomy on Renal Function in Patients With Morbid Obesity: A One-Year Prospective Cohort Study

“…We conducted an observational prospective cohort study that included consecutive patients admitted to our institution to undergo sleeve gastrectomy between January 2013 and November 2016. As previously described 21 , patients ful lling the following criteria were considered to be eligible for this study: (i) severe obesity [body mass index (BMI) ≥ 35 kg/m 2 ] with at least one comorbid condition or morbid obesity alone (BMI ≥ 40 kg/m 2 ) not responsive to medical treatment, (ii) no medical or psychological contraindication for bariatric surgery, (iii) not currently an excessive drinker, as de ned by a mean daily consumption of more than 20 g of alcohol per day for women or more than 30 g of alcohol per day for men, (iv) no long-term consumption of hepatotoxic drugs, and (v) negative screening results for chronic liver disease unrelated to obesity. All patients had a pre-operative evaluation including: (i) a biological assessment of renal function, lipid pro le, nutritional status, and liver function tests, and (ii) liver ultrasound and transient elastography 21 .…”

“…A liver biopsy was performed during the sleeve gastrectomy as previously described 22 . The indications for liver biopsy were: (i) ultrasound results suggestive of liver steatosis or liver dysmorphia and/or (ii) abnormal liver tests and/or (iii) a macroscopically abnormal liver, as observed by the surgeons 21 . A computerized tomography (CT) scan was systematically performed two days and one year after sleeve gastrectomy to detect early and late complications of surgery.…”