Radiographic improvement of hepatic steatosis after Roux-en-Y gastric bypass.

Joshua S Winder, MD, Brandon J Dudeck, BS, Jerome R Lyn-Sue, MD, Randy S Haluck, MD, Ann M Rogers, MD. Penn State Hershey Medical Center

Introduction

 Due to the increasing rates of obesity in developed countries, nonalcoholic fatty liver disease (NAFLD) is now the most common form of liver disease and the leading cause of cirrhosis in those regions. As such it is also a risk factor for hepatocellular carcinoma. Prior studies have shown improvement of liver histopathology after significant weight loss. However, biochemical studies and sonography have not been shown to be definitive in showing improvement. Computed tomographic (CT) findings of NAFLD include low attenuation of liver parenchyma and hepatomegaly.  We hypothesized that patients  undergoing laparoscopic Roux-en-Y gastric bypass (RYGB) and experiencing significant weight loss would have radiographic improvement of their NAFLD.

Methods

A retrospective review was performed of all patients who underwent RYGB at this institution.   We then identified patients who had either a preoperative abdominal CT scan or an early postoperative scan (prior to  significant weight loss) as well as those patients with a CT scan performed  at more than 60 days after surgery for any indication.  The radiologists’ interpretations were reviewed and all  descriptions of steatosis, fatty infiltration, fatty liver, fatty changes, or hypodense liver were documented.  Furthermore, any noncontrast CT scans that met diagnostic criteria for steatosis (liver parenchyma measuring ≤40 Hounsfield units averaged at 3 locations) were noted.  Later scans were  searched for similar criteria as well as evidence of improvement.

Results

19 patients were identified as having perioperative radiographic evidence of NAFLD.  89.5% were female with an average age of 41.5 years and a median body mass index (BMI) of 46.9 kg/m2.  16 of these patients (84.2%) showed radiographic improvement of their NAFLD (Figure).  The median time period from initial CT to postoperative CT was 826 days, and the median BMI at that time point was 30.5kg/m2 .  The three patients who did not experience radiographic improvement still experienced weight loss (average BMI points lost of 19.3 kg/m2).

Conclusions

Although the functional status of the liver was not examined in this study, the radiographic improvement of NAFLD in this series in 84% of patients was significant.  Routine liver biopsy during bariatric surgery is probably not indicated. Obesity  clearly plays a role in the pathophysiology of NAFLD, although this does not fully explain our results of 3 patients with substantial weight loss but ongoing radiographic evidence of NAFLD. 

Figure: Left: Preprocedure hypo-attenuation of liver.  Right: Same patient post-procedure, now with higher attenuating liver parenchyma outlining hypodense hepatic vessels.