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Background: To determine whether MRI feature analysis can differentiate benign retroperitoneal extra-adrenal paragangliomas and schwannomas., Methods: The MRI features of 50 patients with confirmed benign retroperitoneal extra-adrenal paragangliomas and schwannomas were retrospectively reviewed by two radiologists blinded to the histopathologic diagnosis. These features were compared between two types of tumours by use of the Mann-Whitney test and binary logistic regression. The patients' clinical characteristics were reviewed., Results: Analysis of MRI images from 50 patients revealed no significant differences in the quantitative MRI features of lesion size, ratio of diameter and apparent diffusion coefficient. There were significant differences in the qualitative MRI features of location, necrosis, cysts and degree of tumour enhancement for two readers, with no significant differences in the other qualitative MRI features between these tumours. The combination of necrosis with degree of tumour enhancement during the arterial phase increased the probability that a retroperitoneal mass would represent retroperitoneal extra-adrenal paraganglioma as opposed to schwannoma., Conclusion: We have presented the largest series of MRI features of both benign retroperitoneal extra-adrenal paragangliomas and schwannomas. Some MRI features assist in the differentiation between these tumours, with imaging features consisting of necrosis and avid enhancement during the arterial phase, suggestive of retroperitoneal extra-adrenal paragangliomas.

Purpose: To document the magnetic resonance imaging (MRI) characteristics of paraganglioma of the urinary bladder in adults., Materials and Methods: The MRI findings and clinical features of pathologically-proven bladder paraganglioma in four patients (three men, one woman; age range, 39-62 years; mean age, 46.8 years) were reviewed retrospectively. All patients underwent MRI in a 1.5 T instrument. The MRI features of the lesions were analyzed, with emphasis on the size, shape, location, margin, signal intensity, degree of MRI enhancement, and apparent diffusion coefficient (ADC) values., Results: The bladder paragangliomas were located in the posterior vesicle wall (n=2), in the dome of the bladder wall (n=1), or the inferoanterior wall (n=1). On MR images, the tumors were round (n=1) or oval-shaped (n=3) and all exhibited well-circumscribed margins and broad-based attachment to the bladder wall. On T1-weighted images, the lesions demonstrated homogeneous hyperintensity (n=4) compared to the gluteus maximus muscle; while on T2-weighted images, they showed slight hyperintensity (n=4). On contrast-enhanced MR images, all lesions showed intense enhancement. On diffusion-weighted imaging (DWI), the lesions showed hyperintensity (n=4) and the mean ADC value was 0.973×10(-3) mm2/s., Conclusion: Bladder pheochromocytoma appears as a round or oval-shaped intensely enhancing lesion with T1 hyperintensity; these characteristics may facilitate the preoperative determination., (Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.)

Bladder paraganglioma (BPG) is a rare extra-adrenal pheochromocytoma with variable symptoms and easy to be misdiagnosed and mishandled. The aim of the study was to document the imaging features of BPG using computed tomography (CT) and magnetic resonance imaging (MRI).

Bladder paraganglioma (BPG) is a rare extra-adrenal pheochromocytoma with variable symptoms and easy to be misdiagnosed and mishandled. The aim of the study was to document the imaging features of BPG using computed tomography (CT) and magnetic resonance imaging (MRI). We retrospectively enrolled consecutive patients with pathology-proven BPG, who underwent CT or MRI examinations before surgery between October 2009 and October 2017. The clinical characteristics, CT, and MRI features of the patients were described and analysed. A total of 16 patients with 16 bladder tumours (median age 51 years, 9 females) were included. Among them, 13 patients underwent CT examinations and eight patients underwent MRI examinations preoperatively. Tumour diameters ranged from 1.6−5.4 cm. Most of the tumours grew into the bladder cavity (n = 11) with oval shapes (n = 10) and well-defined margins (n = 14). Intratumour cystic degeneration or necrosis (n = 2) was observed. Two lesions showed peripheral tissue invasion, suggesting malignant BPGs. All 13 lesions imaged with CT exhibited slight hypoattenuation and moderate to marked enhancement. Compared to the gluteus maximus, all lesions showed slight h yperintensity in T2-weighted images, hyperintensity on diffusion-weighted images (DWI), hypointensity on apparent diffusion coefficient maps, hyperintensity on T1-weighted images and a "fast in and slow out" enhanced pattern on contrast-enhanced MRI images. BPGs are mostly oval-shaped, broadly-based and hypervascular bladder tumours with hypoattenuation on non-contrast CT, T2 hyperintensity, slight T1 hyperintensity compared to the muscle, marked restricted diffusion on DWI. Peripheral tissue invasion can suggest malignancy of the BPGs. All of these features contribute to preoperative decision-making. [ABSTRACT FROM AUTHOR]