CT attenuation offers insight into pancreatic fat, diabetes

CT attenuation indexes are correlated with pancreatic fat and associated with pancreatic dysfunction that could lead to diabetes, according to a study published online Jan. 16 in Radiology.

The findings indicate that unenhanced CT could have a role in predicting glucose homeostasis, wrote So Yeon Kim , MD, of Seoul National University College of Medicine, Korea, and colleagues.

A reliable, noninvasive technique for quantifying pancreatic fat is important because of the potential for pancreatic dysfunction fatty infiltration can cause, explained the authors. However, there was concern that while CT could indicate fatty infiltration through a decrease in attenuation, it could also be affected by other components, such as manganese, that could mask changes in attenuation.

To assess the relationship between CT indexes and histologically measured pancreatic fat as well as the correlation with impaired glucose metabolism, Kim and colleagues conducted a retrospective study of records at their institution from November 2008 to April 2009. A total of 62 patients—42 of whom were men with a mean age of 61.4 years—who underwent CT within a month before pancreatectomy were included in the study.

The authors measured the histologic pancreatic fat fraction in nontumorous tissue and measured attenuation in three regions of interest in the pancreas and spleen in order to calculate the difference between pancreatic and splenic attenuation.

Results showed that pancreatic fat fraction, which ranged from 0 percent to 65.3 percent, was significantly correlated with the difference between pancreatic and splenic attenuation as well as the pancreas-to-spleen attenuation ratio. CT attenuation indexes were also shown to be significant and independent variables that predicted impaired glucose metabolism.

“Although CT indexes allowed discrimination of patients with normal glucose metabolism from those with impaired glucose metabolism, a subgroup analysis did not show a statistically significant difference and was underpowered for detection of the differences according to the degree of impaired glucose metabolism,” wrote the authors.

A study featuring a larger number of patients will be required to validate the clinical implications of pancreatic fat measurement in the prediction of impaired glucose metabolism, noted Kim and colleagues.

They added that while MRI has been established as an accurate tool for quantification of hepatic fat, applying it to pancreatic fat will have to wait for technical advances that allow it to be less challenging to perform and comparable with CT. “Until that point, CT appears to be a more practical clinical imaging modality for the quantification of pancreatic fat.”