Dual-energy CT using iodine quantification improves early acute pancreatitis diagnosis

Dual-energy computed tomography (DECT) using iodine quantification produces a higher sensitivity for early acute pancreatitis compared to standard computed tomography image evaluation, according to a team of researchers from Germany, Italy, and the United States. They reached this conclusion after studying the performance of a DECT-based technique using iodine quantification and fat fraction analysis, reporting their findings in the May 2019 European Radiology.

Detecting early acute pancreatitis can be challenging on CT, unlike the detection of severe pancreatitis. In early or mild acute pancreatitis, peripancreatic inflammation, necrosis, or focal fluid collections may not be apparent.

The study cohort included 45 patients presenting with abdominal pain suggestive of pancreatitis and elevated serum lipase levels three or more times than normal. They included 35 men and 10 women, ranging in age from 18 to 95 years. A control group of 35 men who did not have a tumor history or chronic pancreatitis and with normal serum lipase, were also recruited, matched by age, body mass index, and clinical inclusion criteria.

The abdominal CT studies were independently evaluated by three radiologists. They assessed each case to determine the presence or absence of pancreatitis, and in a subsequent viewing, manually placed region-of-interest (ROI) measurements on pancreatic-phase DECT material density images in the head, body, and tail of the pancreas in each patient. They also collected and recorded normalized attenuation values. The researchers then compared mean values of iodine density and fat fraction between inflammatory and normal pancreatic parenchyma.

Simon Martin, MD, of the Department of Diagnostic and Interventional Radiology of the University Hospital Frankfurt, and co-authors reported that DECT-based iodine density values showed significant differences between inflammatory and normal pancreatic parenchyma, whereas fat fraction measurements showed no significant difference. The optimal iodine density threshold for the diagnosis of acute pancreatitis was 2.1 mg/mL, with a sensitivity of 96%, a specificity of 77%, and an area under the curve (AUC) of 0.86. In comparison, standard image evaluation resulted in a sensitivity of 78%, a specificity of 82%, and an AUC of 0.80.

“Material density analysis provided a more direct measure of iodine presence within the pancreas that resulted in a higher diagnostic accuracy in comparison to attenuation measurements,” they wrote. “DECT with iodine quantification allows for differentiation between normal and inflammatory pancreatic parenchyma and may substantially improve the sensitivity as a diagnostic test for the detection of early acute pancreatitis.”

Co-author Julian Wichmann, MD, also of the Department of Diagnostic and Interventional Radiology of the University Hospital Frankfurt, commented to Applied Radiology, “Abdominal imaging has been a focus of new DECT techniques for years, particularly for tumor evaluation. Our work supports the growing role of DECT in routine abdominal imaging, which is standard at our institution.”

REFERENCE

1. Martin SS, Trapp F, Wichmann JL, et al. Dual-energy CT in early acute pancreatitis: improved detection using iodine quantification. Eur Radiol. 2019;29(5):2226-2232.