MR imaging features of benign retroperitoneal paragangliomas and schwannomas

Abstract

BackgroundTo determine whether MRI feature analysis can differentiate benign retroperitoneal extra-adrenal paragangliomas and schwannomas.MethodsThe 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.ResultsAnalysis 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.ConclusionWe 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.

Schwannoma Misdiagnosed as Adrenal Adenoma: A Case Report and Review of the Literature

“…Schwannomas usually appear as a well-circumscribed, homogenous, and round or oval lesion, with slight enhancement on the CT scan with cystic degeneration or calcification [10]. In one study, it was found that the combination of necrosis with a minimal degree of tumor enhancement in the arterial phase of the CT scan increased the probability of ruling out schwannoma [11]. Furthermore, the schwannomas on MRI appear as a well-circumscribed mass with cystic degenerative changes with low signal intensity on T1-weighted images and heterogeneous high signal intensity on T2-weighted images.…”

Retroperitoneal paraganglioma: a chameleon masquerading as an adrenal pheochromocytoma

“…Retroperitoneal paragangliomas are rare tumours arising from chromaffin cells along the autonomic nervous system, with an estimated incidence of 2-8 per million, 1 accounting for 1-3% of retroperitoneal tumors. 3 Those paragangliomas arising from the medulla are known as pheochromocytomas, which comprise nearly 70% of such cases. 4 Paragangliomas are known to occur in various locations in the body such as the head and neck, thorax and abdomen.…”

“…On T1 weighted images, tumours appear similar to liver and muscle with an enhancement observed in T2 and diffusion-weighted image, confirming the diagnosis. 3 Nuclear imaging in the form of I123 MIBG and F18-fluorodopa positron emission tomography (PET) is also useful in the diagnosis of these enigmatic tumours. 123 MIBG has a sensitivity of 92-98% for non-metastatic tumours and 57-79% for detecting metastases.…”

Diagnostic Biomarkers for Alzheimer’s Disease Using Non-Invasive Specimens

“…All of the studies used an enzyme-like immunosorbent assay (ELISA) as their main experimental approach to detect Aβ. Most of the studies (5/7) demonstrated increased levels of Aβ42 in AD patients [ 52 , 53 , 54 , 55 , 56 ] while the others (2/7) showed undetectable or unchanged Aβ42 levels [ 42 , 57 ]. With the exception of a relatively larger study by Bermejo-Pareja et al [ 55 ], including 70 AD patients and 56 healthy volunteers serving as the study’s controls, the remaining studies reported results on much smaller cohorts ranging from 7–28 AD patients and 7–38 healthy controls.…”

“…More specifically, Sabbagh et al [ 52 ] recruited 15 AD patients (7 males, mean age: 77.8 years, mean mini-mental state examination (MMSE) score 19.0) and 7 normal controls (2 males, mean age: 60.4 years, mean MMSE 29.0) and demonstrated significantly higher salivary Aβ42 in AD patients than in controls (51.7 ± 1.6 pg/mL for AD and 21.1 ± 0.3 pg/mL for controls, p < 0.001). Participants were enrolled as mild and moderate AD according to the AD criteria established by the National Institute on Aging and the Alzheimer’s Association (NIA-AA) [ 79 ].…”