Perioperative Computed Tomography Assessments of the Pancreas Predict Nonalcoholic Fatty Liver Disease After Pancreaticoduodenectomy

Abstract

Nonalcoholic fatty liver disease (NAFLD) after pancreaticoduodenectomy (PD) has become a clinically important issue. Although pancreatic exocrine insufficiency has been reported to be a main cause of NAFLD after PD, a clinically practical examination to assess the pancreatic exocrine function has not been established. The aim of this study was to evaluate risk factors for NAFLD after PD with a focus on perioperative computed tomography (CT) assessments of the pancreas.A retrospective review of 245 patients followed for more than 6 months after PD was conducted. We evaluated several pancreatic CT parameters, including the pancreatic parenchymal thickness, pancreatic duct-to-parenchymal ratio, pancreatic attenuation, and remnant pancreatic volume (RPV) on pre- and/or postoperative CT around 6 months after surgery. The variables, including the pancreatic CT parameters, were compared between the groups with and without NAFLD after PD.The incidence of NAFLD after PD was 19.2%. A multivariate analysis identified 5 independent risk factors for NAFLD after PD: a female gender (odds ratio [OR] 5.66, P < 0.001), RPV < 12 mL (OR 4.73, P = 0.001), preoperative pancreatic attenuation of <30 Hounsfield units (OR 4.50, P = 0.002), dissection of the right-sided nerve plexus around the superior mesenteric artery (OR 3.02, P = 0.017) and a preoperative serum carbohydrate antigen 19-9 level of ≥70 U/mL (OR 2.58, P = 0.029).Our results showed that 2 pancreatic CT parameters, the degree of preoperative pancreatic attenuation and RPV, significantly influence the development of NAFLD after PD. Perioperative CT assessments of the pancreas may be helpful for predicting NAFLD after PD.

FIGURE 1

Liver and spleen attenuation values were measured on unenhanced computed tomography images. The degree of liver attenuation was measured in 4 regions of interest in different sectors in the liver. The degree of spleen attenuation was measured in 1 region of interest in the spleen.

FIGURE 2

Extent of pancreatic parenchymal attenuation was measured in 3 regions of interest at different locations in the body and tail of the pancreas on preoperative unenhanced computed tomography images (A). Enhanced images in the late arterial phase were reviewed side by side with unenhanced images in order to identify and exclude the main pancreatic duct and major vessels (B).

FIGURE 3

Diameter of the main pancreatic duct (MPD) (D) and thickness of the pancreas (T) were measured on enhanced computed tomography images. Preoperatively, the values were measured along the line at the left edge of the superior mesenteric vein (SMV) (A). Postoperatively, the parameters were measured at the greatest length of the MPD in the remnant pancreas (B).

FIGURE 4

In order to measure the remnant pancreatic volume, the pancreatic parenchyma was manually outlined using a free-hand region of interest on postoperative computed tomography images obtained in the equilibrium phase. Major vessels and dilated pancreatic ducts (3 mm or more) were excluded.