Tumor-Vessel Relationships in Pancreatic Ductal Adenocarcinoma at Multidetector CT: Different Classification Systems and Their Influence on Treatment Planning

Abstract

Treatment of pancreatic ductal adenocarcinoma (PDAC) remains a challenge, given its propensity for early systemic spread and growth into the adjacent vital vascular structures. With the advent of newer surgical techniques and chemoradiation therapies, multidetector computed tomography (CT) plays a crucial role in the identification of patients with borderline resectable disease who may benefit from such treatments. Stage III PDAC is divided into two categories-locally advanced, defined by arterial encasement or nonreconstructible portovenous axis involvement; and borderline resectable, defined by limited arterial involvement and/or reconstructible portovenous involvement. A consensus definition for stage III borderline resectable PDAC has been proposed by the Americas Hepato-Pancreato-Biliary Association, the Society of Surgical Oncology, and the Society for Surgery of the Alimentary Tract and has gained widespread use. Evaluation of borderline resectable disease involves the identification of the circumferential and longitudinal relationship of the tumor with its neighboring vessels, markers of vascular invasion, and aberrant anatomic structures that alter the surgical approach. Furthermore, the use of template-based radiology reporting may increase the objectivity of the evaluation and mandate the provision of all of the key descriptors required for a comprehensive evaluation of the disease. In this review, the staging of PDAC at multidetector CT is described, with reference to the evaluation of the tumor-vessel interface as it guides treatment planning, along with a discussion of the key descriptors of PDAC at multidetector CT and their importance. Examples are provided of the imaging findings of borderline resectable disease and different surgical approaches, along with a discussion on the importance of standardized terminology and template-based reporting. RSNA, 2016.

Imaging diagnosis and staging of pancreatic ductal adenocarcinoma: a comprehensive review

“…Axial, coronal, and sagittal reconstructions should be examined thoroughly to assess the tumor contact with the circumference and long axis of the vessels. Maximum intensity projections (MIP) images and volume-rendered images are useful in detecting subtle changes in vascular calibers [41]. MR imaging including MR angiography is an excellent alternative option with a sensitivity and specificity comparable to CT [1,15,39,42].…”

“…Tumor abutment is defined as circumferential tumor contact ≤ 180°with the vessel, and tumor encasement refers to > 180°tumor contact with the vessel [9,46,47]. Teardrop sign, an altered shape of the affected vein on axial CT images due to tumor encasement or desmoplastic reaction, is highly associated with venous invasion [41,48]. Morphological changes of the artery carry a higher risk of invasion compared with the vein.…”

“…Morphological changes of the artery carry a higher risk of invasion compared with the vein. Tumor encasement of the arteries on CT has a sensitivity of up to 80% and a specificity of 98% for vascular invasion [41,49].…”

“…The presence of anatomic arterial variants increases the risk for intraoperative vascular injuries and postoperative complications such as hepatic ischemia, biliary anastomotic leak, and pseudoaneurysms. Hepatic arterial anatomic variations occur in 55-79% of the patients and include a replaced right or left hepatic artery, an accessory right or left hepatic artery, and a hepatomesenteric trunk, where the common hepatic trunk arises from the SMA [41,48]. Preoperative diagnosis of these variations can aid in surgical planning and selecting the vascular reconstruction technique to reserve the aberrant artery and avoid vascular injury.…”

“…The radiologist should report the arterial variant especially the presence of a replaced hepatic artery or hepatomesenteric trunk because they may determine tumor resectability. The report should also describe the absence or presence and degree of tumor contact with the aberrant artery [9,41].…”