Pancreatic carcinoma coexisting with chronic pancreatitis versus tumor-forming pancreatitis: diagnostic utility of the time-signal intensity curve from dynamic contrast-enhanced MR imaging

Abstract

Aim: To evaluate the ability of the time-signal intensity curve (TIC) of the pancreas obtained from dynamic contrast-enhanced magnetic resonance imaging (MRI) for differentiation of focal pancreatic masses, especially pancreatic carcinoma coexisting with chronic pancreatitis and tumor-forming pancreatitis.

Methods: Forty-eight consecutive patients who underwent surgery for a focal pancreatic mass, including pancreatic ductal carcinoma (n=33), tumor-forming pancreatitis (n=8), and islet cell tumor (n=7), were reviewed. Five pancreatic carcinomas coexisted with longstanding chronic pancreatitis. The pancreatic TICs were obtained from the pancreatic mass and the pancreatic parenchyma both proximal and distal to the mass lesion in each patient, prior to surgery, and were classified into 4 types according to the time to a peak: 25 s and 1, 2, and 3 min after the bolus injection of contrast material, namely, type-I, II, III, and IV, respectively, and were then compared to the corresponding histological pancreatic conditions.

Results: Pancreatic carcinomas demonstrated type-III (n=13) or IV (n=20) TIC. Tumor-forming pancreatitis showed type-II (n=5) or III (n=3) TIC. All islet cell tumors revealed type-I. The type-IV TIC was only recognized in pancreatic carcinoma, and the TIC of carcinoma always depicted the slowest rise to a peak among the 3 pancreatic TICs measured in each patient, even in patients with chronic pancreatitis.

Conclusion: Pancreatic TIC from dynamic MRI provides reliable information for distinguishing pancreatic carcinoma from other pancreatic masses, and may enable us to avoid unnecessary pancreatic surgery and delays in making a correct diagnosis of pancreatic carcinoma, especially, in patients with longstanding chronic pancreatitis.

Figure 1

Patterns of the time-signal intensity curve (TIC) from dynamic contrast-enhanced magnetic resonance imaging of the pancreas.

Figure 2

Representative pancreatic TIC profiles in patients with pancreatic ductal carcinoma developed in a normal pancreas. A, B: Dynamic contrast-enhanced MRI images of the pancreas in a 59-year-old man with carcinoma of the head of the pancreas. The ROIs are placed at the pancreatic mass (No.2 ROI) and the non-tumorous pancreatic parenchyma both proximal (No.1 ROI) and distal (No.3 ROI) to the mass lesion; C: Pancreatic TICs obtained from the no.1 and no. 2 ROIs as in (A) demonstrate type-I and type-IV, respectively; D: Pancreatic TIC obtained from the No.3 ROI as in Figure 2B shows type-II.

Figure 3

Pancreatic carcinoma occurring in a 67-year-old man with a longstanding chronic pancreatitis. A: An abdominal contrast-enhanced CT image shows a focal enlargement of the head of the pancreas. The tumor-to-parenchymal attenuation difference is obscure. The patient underwent a laparotomy under a diagnosis of tumor-forming pancreatitis presenting with obstructive jaundice and was found to have pancreas head carcinoma during the operation; B, C: Dynamic contrast-enhanced MRI images of the pancreas. The ROIs are placed at the focally enlarged pancreas head (No.2 ROI), the proximal side of the head of the pancreas (No.1 ROI) , and the body of the pancreas (No.3 ROI); D: Pancreatic TICs obtained from the No.1 and No.2 ROIs as in (B) demonstrate type-II and type-IV, respectively; E: Pancreatic TIC obtained from the No.3 ROI as in (C) shows type-III.

Figure 4

Tumor-forming pancreatitis in a 70-year-old man with a long history of alcohol abuse. The patient underwent a pylorus-preserving pancreaticoduodenectomy together with lymphadenectomy for a suspected pancreas head carcinoma associated with obstructive jaundice and was confirmed to be chronic pancreatitis after surgery. A, B: Dynamic contrast-enhanced MRI images of the pancreas. The ROIs are placed at the pancreatic mass (No.2 ROI) and the pancreatic parenchyma both proximal (nNo.1 ROI) and distal (No.3 ROI) to the mass lesion; C: Both of the pancreatic TICs obtained from the No.1 and no.2 ROIs as in Figure 4A demonstrate type-II; D: Pancreatic TIC obtained from the No.3 ROI as in Figure 4B also shows type-II.