He An, Presenter: Nothing to Disclose

Yu Shi PhD, Abstract Co-Author: Nothing to Disclose

Qiyong Guo MD, Abstract Co-Author: Nothing to Disclose

Differential diagnosis of pancreatic masses remains as an important clinical challenge nowadays. Recently, we conducted a prospective study to assess the ability of MR Elastography (MRE) to evaluate the shear stiffness in patients with pancreatic benign and malignant masses. Hence, the purpose of this study was to evaluate the potential value of MRE in the characterization of pancreatic tumors.

22 patients with pancreatic tumors and 10 healthy volunteers underwent 3.0T MRE exam using echo planar imaging (EPI) pulse sequence with low-frequency vibrations (40Hz) between December 2013 and March 2014. The patients included 9 cases with pancreatic benign masses and 13 cases with pancreatic cancer (PC).Cyst with pure liquid and lesion with diameter less than 1.5cm were excluded due to fail for algorithm or detection on elastogram. Except for 5 cases with PC proven by extra-pancreatic metastasis, all the other cases were proven by surgery and pathology. Of the 9 benign cases, 5 were diagnosed with mass-forming pancreatitis (MFP), 2 with cystadenoma, 1 with islet cell adenoma and 1 with pancreatic lipoma. Of the 13 malignant cases, all were diagnosed with Pancreatic Ductal Adenocarcinoma (PDAC).Stiffness was calculated with a 3D direct inversion algorithm. Statistical analysis was performed on the stiffness values for differentiation of normal pancreas, benign tumors and malignant tumors.

Malignant liver tumors had significantly greater mean shear stiffness than both benign tumors (2.04±0.52kPa vs 1.19±0.24kPa,p=0.038) and normal pancreas (2.04±0.52kPa vs 1.21 ±0.08kPa,p=0.001). Benign tumors had similar stiffness values to normal pancreas (1.19±0.24kPa vs 1.21 ±0.08kPa,P=0.07).Within the benign lesions, the MFP had a little greater stiffness than other types of tumors (1.22~1.47kPa vs. 0.67~1.14kPa,P=0.025).

MR Elastography has the unique ability to define benign/healthy pancreas and malignant masses. A hallmark of PDAC is the presence of ‘desmoplasia’, a process in which massive fibrous tissue infiltrates and envelops neoplasm, which might contribute the tumor much harder than the healthy pancreatic tissues. Different types of benign tumors might have varied stiffness due to their diverse mechanical properties.

MR Elastography has the unique ability to define benign/healthy pancreas and malignant tumors and is recommended for the diagnosis of pancreatic masses in clinic. 

An, H, Shi, Y, Guo, Q, Feasibility of Using MR Elastography to Differentiate Benign and Malignant Masses in Pancreas.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14007058.html