Imaging preoperatively for pancreatic adenocarcinoma

Abstract

Pancreatic cancer is a highly lethal malignancy which is increasing in incidence and mortality. The fourth leading cause of cancer death in the U.S., pancreatic cancer is projected to become the second leading cause of cancer death by 2020. Patients with pancreatic cancer have an abysmal 5-year survival of 6%, and 90% of these patients eventually die from the disease. This is in large part due to the commonly advanced stage of disease at the time of diagnosis. Currently, the only potentially curative therapy for pancreatic carcinoma is complete surgical resection. Patients who undergo incomplete resection with residual disease have similar survival rates to those patients with metastatic disease and should be spared this relatively morbid surgery. Thus, the key to impacting prognosis is the detection of smaller and earlier stage lesions, and the key to optimal management is accurately determining which patients have potentially resectable surgery and which patients would not benefit from surgery. Cross-sectional imaging plays an essential role in both the diagnosis and appropriate staging of pancreatic carcinoma. The diagnosis and staging of pancreatic adenocarcinoma is performed with cross-sectional imaging. Multi-detector computed tomography (MDCT) is the most commonly used, best-validated imaging modality for the diagnosis and staging of pancreatic cancer. Modern contrast-enhanced magnetic resonance imaging (MRI) has been demonstrated to be equivalent to MDCT in detection and staging of pancreatic cancer. Endoscopic ultrasound (EUS) is very sensitive for detecting pancreatic masses; however, due to limitations in adequate overall abdominal staging, it is generally used in addition to or after MDCT. Transabdominal ultrasound and positron emission tomography/computed tomography (PET/CT) have limited roles in the diagnosis and staging of pancreatic cancer. Preoperative imaging is used to characterize patients as having resectable disease, borderline resectable disease, locally advanced disease (unresectable) and metastatic disease (unresectable). As the definitions of borderline resectable and unresectable may vary from institution to institution and within institutions, it is essential to accurately assess and describe the factors relevant to staging including: local extent of tumor, vascular involvement, lymph node involvement and distant metastatic disease. To facilitate this, standardized reporting templates for pancreatic ductal adenocarcinoma have been created and published. Structured reporting for pancreatic cancer has been reported to provide superior evaluation of pancreatic cancer, facilitate surgical planning, and increase surgeons' confidence about tumor resectability.

Keywords: Pancreatic cancer; magnetic resonance imaging (MRI); multi-detector computed tomography (MDCT); staging.

Figure 1

A 58-year-old man with stage IV pancreatic adenocarcinoma at presentation. (A) Portal venous phase 5 mm axial MDCT image through the pancreatic body and tail reveals slight dilation of the main pancreatic duct and numerous liver metastases; (B) at a more caudal level, the hypovascular mass in the right aspect of the uncinate process and additional hepatic metastases are noted, note the high density plastic biliary stent and the moderately dilated main pancreatic duct (both seen in cross section). MDCT, multi-detector computed tomography.

Figure 2

A 50-year-old man who underwent abdominal sonography for abdominal pain. (A) Transabdominal sonographic transverse image through the pancreatic body and tail in the upper abdomen shows a poorly marginated hypoechoic lesion (arrow); same patient, multiphasic MDCT the next week demonstrates that the small mass in the posterior pancreatic body and the upstream main pancreatic duct are much better seen on the pancreatic parenchymal phase 2.5 mm axial image (arrow on B) acquired at 35 s after the initiation of IV contrast medium compared to the portal venous phase image (arrow on C) acquired at 70 s. MDCT, multi-detector computed tomography.

Figure 3

A 60-year-old man who presented to the emergency department with nausea and abdominal pain was found to have possible pancreatic head mass. (A) Portal venous phase 5 mm axial image demonstrates fullness in the pancreatic head, but a mass is not clearly discernable. A multiphasic MDCT examination was performed specifically to evaluate potential pancreatic mass; (B) pancreatic parenchymal phase 2.5 mm axial image better demonstrate the margins of the hypovascular mass in the posterior head region compared to either the initial emergency department CT or (C) the 5 mm portal venous phase image obtained as part of the multiphasic pancreatic scan. MDCT, multi-detector computed tomography.

Figure 4

A 63-year-old woman with small pancreatic adenocarcinoma and upstream main pancreatic duct dilation. (A) Coronal reformatted 3 mm MDCT portal venous phase image demonstrates the dilated main pancreatic duct (small arrow) leading in to the 1.0 cm ductal adenocarcinoma (large arrow) in the pancreatic neck region. Note the slightly diminished enhancement of the gland in the body and tail region; the tiny tumor is better depicted on the pancreatic parenchymal phase 2.5 mm axial image (B); compared to the portal venous phase image (C) and appears resectable from a vascular standpoint; however, there is a small metastasis present in the lateral segment of the left lobe of the liver (circle on B). MDCT, multi-detector computed tomography.

Figure 5

A 69-year-old man with a narrowed superior mesenteric vein. (A-D) Successive coronal reformatted images progressing from anterior to posterior demonstrate narrowing of the portal confluence by the hypovascular pancreatic adenocarcinoma in the superior head region, much better depicted, particularly from the standpoint of length of vein involved, on the curved multiplanar reformatted image (E). The axis of this image is aligned with the long axis of the portal vein.

Figure 6

Dual energy MDCT in a 50-year-old man with a small resectable pancreatic ductal adenocarcinoma in the body region (same patient as Figure 2). (A) Low viewing energy (52 keV) axial 2.5 mm image and (B) iodine material density 2.5 mm image demonstrate increased conspicuity of the lesion and its relationship to the adjacent splenic artery (compare to Figure 2B and 2C). MDCT, multi-detector computed tomography.

Figure 7

A 49-year-old woman who underwent upper abdominal MRI to evaluate an incidental hepatic lesion detected on abdominal ultrasound obtained for abdominal pain. (A) Pancreatic parenchymal; and (B) portal venous phase 5 mm axial images well depict the 3.0 cm mass (solid arrows) in the pancreatic body. Note the upstream glandular atrophy and main pancreatic duct dilation (open arrows); the lesion is seen as high (bright) signal on the diffusion weighted image (arrow on C); and is confirmed to have restricted diffusion on the ADC map (arrow on D). MRI, magnetic resonance imaging; ADC, apparent diffusion coefficient.

Figure 8

A 75-year-old man with SMV occlusion and locally advanced pancreatic cancer who underwent PET/CT. (A) Axial PET/CT image through the pancreatic body and neck regions reveals an FDG-avid lesion in the midline (arrow). No distant metastatic lesions were detected, but there is abnormal, less FDG avid activity extending toward the gastric antrum; (B) MRCP image demonstrates focal narrowing of the main pancreatic duct (arrow) in the region of the mass, with upstream dilation in the body and tail; (C) pancreatic parenchymal phase 5 mm axial image; and (D) portal venous phase 5 mm axial image demonstrate the abrupt duct cut off by the small pancreatic mass (small arrows), with an inflammatory collection extending towards the stomach. SMV, superior mesenteric vein; PET/CT, positron emission tomography/computed tomography; FDG, fluorodeoxyglucose; MRCP, magnetic resonance cholangiopancreatography.

Figure 9

An 85-year-old woman with locally invasive pancreatic adenocarcinoma. Pancreatic parenchymal phase axial image demonstrates the low attenuation hypodense mass in the pancreatic neck/body extending through the posterior antral wall and disrupting the enhancing gastric mucosa.

Figure 10

A 61-year-old man with small pancreatic cancer and perineural spread to the celiac ganglion. (A-C) Successively caudal pancreatic parenchymal phase 2.5 mm axial images demonstrate the hypovascular mass in the medial pancreatic head extending posteriorly along the plexus pancreaticus capitalis 1 and abutting the right margin of the celiac trunk. This patient received neoadjuvant therapy.

Figure 11

A 55-year-old woman with SMA encasement. (A) Pancreatic parenchymal phase 2.5 mm axial image depicts the relationship of the hypovascular mass in the medial pancreatic head to the SMA (arrow) where there is ≥180° contact indicating encasement; note that this relationship is better seen on this phase of IV contrast administration compared to (B) the portal venous phase 5 mm axial image. SMA, superior mesenteric artery.

Figure 12

A 52-year-old man with SMA abutment. (A) Pancreatic parenchymal phase 2.5 mm axial image demonstrates contact of the large mass in the pancreatic head with <90° of the SMA (arrow); the SMV (open arrow) is not well evaluated in this phase of contrast, but is better seen on (B) the portal venous phase 5 mm image, where approximately 180° contact is present with slight straightening of the right lateral SMV (open arrow) wall indicating involvement/invasion. SMA, superior mesenteric artery; SMV, superior mesenteric vein.

Figure 13

Cartoon depiction of vascular involvement. (A) Abutment of the C with the V; (B) encasement; and (C) involvement/invasion with teardrop deformity. C, cancer; V, vessel.