MR imaging features of benign retroperitoneal extra-adrenal paragangliomas

Yanguang Shen,Kun Zhang,Yingwei Wang,Zhonghua Sun,Haiyi Wang,Lu Ma,Yan Zhong,Jingjing Pan,Huiyi Ye

doi:10.1038/s41598-017-04753-y

Abstract

The goal of this study was to retrospectively review the magnetic resonance imaging (MRI) features of retroperitoneal extra-adrenal paragangliomas and to evaluate the diagnostic capabilities of MRI. Twenty-four patients with confirmed benign retroperitoneal extra-adrenal paragangliomas who underwent preoperative MRI and surgical resection were enrolled. The patients’ clinical characteristics and MRI features were reviewed by two radiologists. There were no significant differences in the qualitative and quantitative MRI features were determined by the reviewers. High signal intensity in T2-weighted imaging (T2WI) and diffusion-weighted imaging (DWI) was observed in all tumors. In contrast T1-weighted imaging (T1WI) in the arterial phase, 83.33% of the tumors were clearly enhanced. In 87.5% of cases, a persistent enhancement pattern was observed in the venous and delayed phases, and 12.5% of tumors showed a “washout” pattern. The tumor capsule, intratumoral septum and degenerations were visualized in the tumors and may be helpful in the qualitative diagnosis of extra-adrenal paragangliomas in MRI. MRI was useful in locating the position, determining the tumor ranges and visualizing the relationship between the tumors and adjacent structures. The presence of typical clinical symptoms and positivity of biochemical tests are also important factors in making an accurate preoperative diagnosis.

Highlights

Primary neurogenic tumors, which constitute 10% to 20% of primary retroperitoneal tumors, typically occur at younger ages and are usually benign[1]
(2) The results showed that 54.17% of the paragangliomas were located in the prevertebral region, which is close to the aorta and inferior vena cava; no retroperitoneal extra-adrenal paragangliomas were observed in the pelvis
Our study includes the largest series to date describing the magnetic resonance imaging (MRI) features of benign retroperitoneal extra-adrenal paragangliomas with diffusion-weighted imaging (DWI) and dynamic contrast-enhanced MRI (DCE-MRI)

Summary

Introduction

Primary neurogenic tumors, which constitute 10% to 20% of primary retroperitoneal tumors, typically occur at younger ages and are usually benign[1]. Retroperitoneal extra-adrenal paragangliomas account for 1–3% of retroperitoneal tumors, originate in the paraganglionic system and are the most common benign soft-tissue tumors[2, 3]. Patients diagnosed with retroperitoneal extra-adrenal pheochromocytomas typically present with hypertension, tachycardia, headache and diaphoresis[6], other tumors may be completely clinically silent and are only detected incidentally in imaging studies; these tumors are referred to as “incidentalomas”. Any physical contact with these tumors can precipitate cardiac arrhythmias and malignant hypertension[7]. This is the most important reason why urologists and radiologists should, more than ever, understand the imaging appearance of paragangliomas. A description of the MRI features of retroperitoneal extra-adrenal paragangliomas has been reported for only studies with small sample sizes; the purpose of our study was to retrospectively analyze the MRI features of benign retroperitoneal extra-adrenal paragangliomas

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Conclusion