Pancreatic Tumors: Diagnostic Patterns by 3D Gradient-Echo Post Contrast Magnetic Resonance Imaging with Pathologic Correlation

MR imaging features of small solid pseudopapillary tumors: retrospective differentiation from other small solid pancreatic tumors

OBJECTIVE

The purpose of this study was to describe the MRI features of small solid pseudopapillary tumors useful for differentiating these tumors from other small solid pancreatic tumors.

MATERIALS AND METHODS

Forty-five patients (18 men, 27 women; mean age, 59 ± 11.7 years) with 45 solid pancreatic tumors smaller than 3 cm in diameter registered from 2000 to 2009 were included. Twenty-two of the tumors were adenocarcinomas, 12 were endocrine tumors, and 11 were solid pseudopapillary tumors. Two radiologists analyzed the MR images for morphologic features, signal intensity of the lesion on unenhanced images, and dynamic enhancement pattern. The contrast-to-noise ratio between the lesion and the pancreas was calculated on T1- and T2-weighted images and on dynamic images.

RESULTS

Solid pseudopapillary tumors commonly had the following features: completely well-defined margin (82%), pure solid consistency (82%), low signal intensity on unenhanced T1-weighted images (100%), high signal intensity on T2-weighted images (100%), a strong predominance among women (91%), and early heterogeneous and slowly progressive enhancement (100%). The solid pseudopapillary tumors rarely had a capsule or hemorrhage. A characteristic qualitative feature of solid pseudopapillary tumors that was significantly different from the other two tumor types was very high signal intensity on T2-weighted images (p < 0.01). Quantitative analysis showed that the solid pseudopapillary tumors had a lower contrast-to-noise ratio (-16.82 ± 5.84) on T1-weighted images and a higher contrast-to-noise ratio (37.35 ± 33.59) on T2-weighted images than did the other two tumor types (p < 0.01).

CONCLUSION

Small solid pseudopapillary tumors were predominantly seen as completely well-demarcated pure solid tumors in middle-aged women. They had lower signal intensity on T1-weighted images and higher signal intensity on T2-weighted images than did the other two tumor types and had early heterogeneous and progressive enhancement.

Preoperative evaluation of pancreatic cancer: comparison of gadolinium-enhanced dynamic MRI with MR cholangiopancreatography versus MDCT

PURPOSE

To determine the accuracy of magnetic resonance imaging (MRI) including dynamic imaging using three-dimensional gradient-echo (3D-GRE) sequences and MR cholangiopancreatograpy (MRCP) compared with that of multidetector row CT (MDCT) with regard to resectability in pancreas cancer.

MATERIALS AND METHODS

From February 2004 to July 2008, 54 patients (32 men, 22 women: age range, 28-83 years; mean age, 63.1 years old) with surgically proven pancreatic carcinoma, who had undergone preoperative gadolinium-enhanced 3D-GRE MRI with MRCP and triple-phase MDCT, were included in this retrospective study. Two, clinically experienced attending radiologists independently reviewed the two image sets. These readers evaluated the tumor conspicuity, presence of vascular invasion, choledochal and duodenal invasion, lymph node metastases, distant metastasis, and tumor resectability. The results were compared with the surgical and histopathologic findings using receiver operating characteristic analysis (Az) and kappa statistics.

RESULTS

Curative resections were performed on 42 patients. Regarding the tumor conspicuity, MRI had a significantly higher Az value compared with MDCT according to both reviewers (P < 0.05). The accuracy of resectability was Az = 0.753 and 0.768 on MRI and Az = 0.829 and 0.762 on MDCT for each reviewer, and the difference in the accuracy of resectability was not significant between MRI and MDCT for either reviewer (P > 0.05). Two imaging sets showed a similar diagnostic performance in the evaluation of vascular involvement, lymph node metastasis, and distant metastasis.

CONCLUSION

Dynamic 3D-GRE MRI with MRCP shows superior tumor conspicuity and similar diagnostic performance compared with MDCT in evaluating the resectability of pancreatic cancer.

New concepts in staging and treatment of locally advanced pancreatic head cancer

OBJECTIVE

The objective of this article is to discuss the CT findings that guide surgeons in deciding the feasibility of tumor excision in patients with locally advanced pancreatic head cancers.

CONCLUSION

Vascular resection as an adjunct to pancreaticoduodenectomy is increasingly used in pancreatic head cancer. As a result, the imaging criteria to determine which patients are candidates for potentially curative resection are evolving.