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Peripelvic and periureteric areas are frequently overlooked in the imaging evaluations of the urinary system on computed tomography and magnetic resonance imaging. Several neoplastic and non-neoplastic disorders and diseases including lipomatosis, angiomyolipoma and angiolipomatous proliferation, vascular lesions, lymphangiomatosis, Rosai-Dorfman disease, Erdheim-Chester disease, extramedullary hematopoiesis, IgG4-related disease, lymphoma, mesenchymal tumors, trauma, and Antopol-Goldman lesion may involve these areas. Differentiation of these benign or malignant pathologies among themselves and from primary renal pathologies is of utmost importance to expedite the triage of patients for correct treatment approach. In this article, we aim to increase the awareness of the imaging specialists to the typical and atypical imaging features of the entities affecting these areas.

Primary involvement of leptomeninges with melanocytic tumours is rarely seen and its diagnosis is challenging. Here we summarise two cases of primary leptomeningeal melanomatosis presenting as subacute meningitis. Both cases have pleocytosis and high protein on cerebrospinal fluid analysis, and demonstrated atypical cells on cytology. On magnetic resonance imaging, there is diffuse leptomeningal thickening and avid enhancement of intracranial and intraspinal leptomeninges. One of them demonstrates T1 shortening due to magnetic effects of melanin, the other case is amelanotic and shows hypointensity on precontrast T1-weighted images. Both cases can be diagnosed with biopsy. In conclusion, these cases highlight the importance of the correct interpretation of cytological and magnetic resonance imaging findings in patients with atypical findings.

Objectives: Diffusion weighted imaging (DWI) has become important for orbital imaging. However, the echoplanar imaging (EPI) DWI has inherent obstacles due to susceptibility to magnetic field inhomogeneities. We conducted a comparative study assessing the image quality of orbits in a patient cohort with uveal melanoma (UM). We hypothesized that single shot turbo spin echo (ssTSE) DWI would have better image quality in terms of less distortion and artifacts and yield better tissue evaluation compared to ssEPI-DWI. Methods: ssEPI-DWI and ssTSE-DWI of orbits were obtained from 50 patients with uveal melanoma who were prospectively enrolled in the study. Distortion ratio (DR), signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), diffusion signal properties, and apparent diffusion coefficient (ADC) values were collected and compared between ssEPI-DWI and ssTSE-DWI. Two reviewers evaluated and compared the geometric distortion, susceptibility and ghosting artifacts, resolution, demarcation of ocular mass, and overall quality. Results: A higher DR was found in ssEPI-DWI compared to ssTSE-DWI (p < 0.001). SNR and CNR were lower for the temporal lobe cortex (p ≤ 0.004), but higher for melanoma in ssEPI-DWI than ssTSE-DWI (p ≤ 0.037). Geometric distortion and artifacts were more common in ssEPI-DWI (p < 0.001). Resolution (p ≤ 0.013) and overall quality (p < 0.001) were better in ssTSE-DWI. Ocular masses were demarcated better on ssEPI-DWI (p ≤ 0.002). Significant negative correlations between T1 and T2 signal intensities (r = −0.369, p ≤ 0.008) and positive correlations between T2 and both DWI signal intensities (r = 0.686 and p < 0.001 for ssEPI-DWI, r = 0.747 and p < 0.001 for ssTSE-DWI) were revealed. Conclusion: With less geometric distortion and susceptibility artifacts, better resolution, and overall quality, ssTSE-DWI can serve as an alternative to ssEPI-DWI for orbital DWI. Advances in knowledge: ssTSE-DWI can be a better alternative of diffusion imaging of orbits with less susceptibility artefact and geometric distortion compared to ssEPI-DWI.

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Dural sinuses have critical importance during intracranial approaches. Detailed anatomical knowledge of the dural sinuses is crucial for surgeons to reduce unexpected venous bleeding. The aim of this study was to investigate anatomical relation of sigmoid sinus and tentorium cerebelli according to clinically palpable landmarks and cranial morphometry. The authors evaluated 222 individuals’ (94 women, 128 men) 3-dimensional computed tomography angiograms, retrospectively. The authors also studied on 12 mid-sagittal cut dried hemiskulls and 8 formalin fixed cadaver heads hemisected midsagitally. All measurements were completed using Osirix-Lite version 9 software. Craniometrical values were measured to define cranium morphology. Furthermore, level of the sigmoid sinus according to asterion and tentorial angle were evaluated in detail. Our results demonstrated that there were significant differences between parameters and genders, except vertical angle of the tentorium cerebelli. Distance between asterion and sigmoid sinus was statistically different between right and left sides in favor of the left side. This also varied depending on the position of the sigmoid sinus, as well. Only transverse angle between the upper point of external acoustic meatus and asterion demonstrated a significant correlation with age. This study evaluated the detailed 3D anatomy of sigmoid sinus and tentorium cerebelli related with the cranium morphology. Determining to sigmoid sinus anatomy according to clinically palpable landmarks has advantages for setting surgical protocols and reducing to unexpected injuries while surgery to these structures.