Evaluation of dural venous sinuses and confluence of sinuses via MRI venography: anatomy, anatomic variations, and the classification of variations.

Abstract

We aimed to determine the anatomical variations more comprehensively particularly at the level of superior sagittal sinus (SSS), confluence of sinuses (CS), transverse sinuses (TS), straight sinuses (SS) and occipital sinuses (OS) with the help of the images obtained via MRI venography, and to contribute to the classification efforts. In our retrospective study, we evaluated 211 patients who admitted to our hospital with various complaints and cerebral MRI venography has been performed. All investigations were performed by using 1.5-T MRIscanner (Achiva, Philips) with a VEN-3D -PCA MR venous angiography technique. Section thickness was 0.8 mm and axial plane was used. Other parameters were as follows: 17/7.1 (TR/TE), flip angle, 10.00, FOV, 220-mm, and matrix 244x140. We divided our cases into 3 types but we increased the number of subgroups. Type I was divided into 4 subgroups (Type IA, IB, IC, ID), Type II into 9 (Type IIA1, IIA2, IIB1, IIB2, IIC, IID1, IID2, IIE1, IIE2) and Type III into 2 (Type IIIA, IIIB). Type I constitutes a 26.06% of whole cases, and Type II 59.71%, Type III 14.21%. In our cases R-TS wasn't revealed in 10 cases (4.73%) whereas in 37 cases (17.53%) it was hypoplastic. L-TSwasn't shown in 26 cases (12.32%) and in 85 cases (49.09%) it was hypoplastic. R-Sig S wasn't revealed in 7 (3,31%) and was hypoplastic in 34 (16.11%) whereas L-Sig S wasn't present in 2 (0.94%) and hypoplastic in 72 (34.12%). Among these cases 14 had bilateral hypoplastic TS (6.63%). In cases with hypoplastic TS or Sig S, as an alternative pathway 30 patients had OS (14.21%). Two of these patients had double OS. Our wish is to contribute to the efforts of clarifying and classifying the intracranial venous structures and their anatomical variations. We hope our study enlightens a path in this field for future studies.