Correlation between pathology and quantitative ultrasonographic evaluation of pancreatic fat with ultrasonographic classification.

Abstract

No studies of the relationship between grayscale sonographic findings and pancreatic fat content have been reported to date. This study aimed to investigate the correlation between echogenicity and fat content of resected specimens using quantitative analysis. Forty-two consecutive patients who underwent pancreatoduodenectomy or distal pancreatectomy for pancreatic tumors were enrolled in this study. Ultrasonographic images were compared with quantitative pathological analysis. Subjective evaluation of echogenicity was classified as hypoechoic, isoechoic, hyperechoic, and super hyperechoic. The total and intralobular fat areas were measured. The mean, median, modal, minimum, and maximum ultrasound gray values correlated with the proportion of total fat area (r = 0.349; 0.357, 0.486, 0.466, and 0.347; p = 0.024, 0.020, 0.014, 0.019, and 0.089, respectively), but did not correlate with the proportion of intralobular fat area. Subjective classification was correlated with median gray value (p < 0.001), intralobular fat area (p = 0.118), and total fat area (p = 0.011). Cases were classified as hypoechoic (n = 3), isoechoic (n = 7), hyperechoic (n = 30), and super hyperechoic (n = 2). The subjective classification was correlated with the median gray value (p < 0.001) and total fat area (p = 0.005), and not correlated with the intralobular fat area (p = 0.118). Hyperechoic or super hyperechoic pancreatic parenchyma contains over 19.7% fat. Computed tomography values correlated with the proportion of intralobular fat area (r = -0.479, p = 0.004) and total fat area (r = -0.541, p < 0.001). Echogenicity classified based on subjective evaluation and image analysis were correlated with the proportion of fat in the pancreas.