Visualization of Anatomic Variation of the Anterior Septal Vein on Susceptibility-Weighted Imaging

RESEARCH ARTICLE Visualization of Anatomic Variation of the Anterior Septal Vein on SusceptibilityWeighted Imaging Zhengzhen Chen1, Huihuang Qiao2, Yu Guo1, Jiance Li3, Huizhong Miao1, Caiyun Wen3, Xindong Wen3, Xiaofen Zhang1, Xindong Yang1, Chengchun Chen1* 1 Department of Human Anatomy, Wenzhou Medical University, Wenzhou, Zhejiang, China, 2 Department of Radiology, The 2nd hospital of Huangshi, Huangshi, Hubei, China, 3 Department of Radiology, the 1st Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China * a11111 Abstract Background and Purpose OPEN ACCESS Citation: Chen Z, Qiao H, Guo Y, Li J, Miao H, Wen C, et al. (2016) Visualization of Anatomic Variation of the Anterior Septal Vein on SusceptibilityWeighted Imaging. PLoS ONE 11(10): e0164221. doi:10.1371/journal.pone.0164221 Editor: Yen-Yu Ian Shih, University of North Carolina at Chapel Hill, UNITED STATES Received: April 28, 2016 Accepted: September 21, 2016 Published: October 7, 2016 Copyright: © 2016 Chen et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: All relevant data are within the paper and its Supporting Information files. Funding: This work was supported by the Natural Science Foundation of Zhejiang Province, China (NO.LY15C110001). Competing Interests: The authors have declared that no competing interests exist. Understanding the anatomy of the anterior septal vein (ASV) is critical for minimally invasive procedures to the third ventricle and for assessing lesion size and venous drainage in the anterior cranial fossa. Accordingly, this study evaluated topographic anatomy and anatomic variation of the ASV using susceptibility-weighted imaging (SWI). Methods Sixty volunteers were examined using a 3.0T MR system. The diameter of the ASV and distance between bilateral septal points were measured. ASVs were divided into types 1 (only drains frontal lobe) and 2 (drains both frontal lobe and head of the caudate nucleus). We evaluated the ASV-internal cerebral vein (ICV) junction based on its positional relationship with the appearance of a venous angle or a false venous angle and the foramen of Monro. Fused SW and T1-weighted images were used to observe positional relationships between the course of the ASV and the surrounding brain structures. Results The ASV and its small tributaries were clearly visualized in 120 hemispheres (100%). The average diameter of ASVs was 1.05±0.17 mm (range 0.9–1.6 mm). The average distance between bilateral septal points was 2.23±1.03 mm (range 1.3–6.6 mm). The ASV types 1 and 2 were in 77 (64.2%) and 43 (35.8%) hemispheres, respectively. In 83 (69.2%) hemispheres, the ASV-ICV junction was situated at the venous angle and the posterior margin of the foramen of Monro. In 37 (30.8%) hemispheres, the ASV-ICV junction was situated beyond the posterior margin of the foramen of Monro. The average distance between the posteriorly located ASV-ICV junction and the posterior margin of the foramen of Monro was 6.41±3.95 mm (range 2.4–15.9 mm). PLOS ONE | DOI:10.1371/journal.pone.0164221 October 7, 2016 1 / 13 Anatomic Variation of the Anterior Septal Vein Conclusion Using SWI, the topographic anatomy and anatomic variation of the ASV were clearly demonstrated. Preoperative assessment of anatomic variation of the ASV may be advantageous for minimally invasive neurosurgical procedures. Introduction As one of the subependymal veins, the chief function of the anterior septal vein (ASV) is to drain the deep white matter of the frontal lobe via deep medullary veins [1]. Various diseases have been shown to be associated with abnormalities of the deep medullary veins, such as stroke [2, 3], leukoaraiosis [4], and developmental venous anomaly [5]. Abnormalities of deep medullary veins in the frontal lobe may reflect poor reflux of the ASV. Previous studies have described the anatomy of the ASV using angiography, magnetic resonance venography (MRV), or autopsies [6–8]. However, those methods have certain disadvantages, such as invasiveness, use of radioactive materials, inefficiency, technical issues that render it difficult to distinguish anatomical variance, and inadequate resolution to visualize small tributaries of the ASV. Some scholars have suggested that the junction formed by the ASV and the internal cerebral vein (ICV) may play a significant role in minimally invasive procedures to the third ventricle [8–11]. However, there is a lack of research regarding methods of imaging the ASV and its small tributaries. Susceptibility-weighted imaging (SWI), such as T2 -weighted angiography (SWAN, General Electric), susceptibility weighted imaging (SWI, Siemens), and venous blood oxygen-level dependent imaging (VenoBOLD, Philips) are useful and relatively novel magnetic resonance imaging (MRI) sequences that exploit susceptibility differences between the venous deoxygenated blood and the surrounding brain tissues [12–14]. Deoxyhemoglobin serves as an intrinsic contrast agent to generate the high-resolution venous images. Compared with conventional MRI sequences, SWI has higher sensitivity to detect deoxygenated hemoglobin, calcification, and iron content [12]. Increasingly many clinical applications of SWI of the brain have been reported, such as prediction of stroke severity [2, 3], dural arteriovenous fistula [15], and cerebral neoplasms [16]. Currently, SWI is also widely used in visualization of the cerebral venous system [17–19]. To our knowledge, there is a lack of available research describing the use of SWI to visualize the ASV in detail. In this study, we illustrate the topographic anatomy and anatomic variation of the ASV by application of SWI in a healthy cohort. Materials and Methods Volunteer Selection Participants were 60 healthy volunteers (28 females and 32 males; age range 18–30 years; average age 26.1 years). None had cerebral disease or cerebral trauma. Informed consent forms were obtained from all volunteers. This study was approved by the Ethics Committee of Wenzhou Medical University. MR Imaging Technique All volunteers were scanned via a 3.0 Tesla TX-series MRI scanner (Royal Philips Electronics, Amsterdam, Netherlands) with an 8-channel high-resolution brain-phased array coil. The following scan protocols were performed: (1) T1-weighted imaging (T1WI) and fluid-attenuated PLOS ONE | DOI:10.1371/journal.pone.0164221 October 7, 2016 2 / 13 Anatomic Variation of the Anterior Septal Vein inversion recovery (FLAIR) sequence (repetition time [TR]/echo time [TE] = 1900 ms/20 ms, flip angle = 90°, image matrix = 256 × 141, field of view [FOV] = 230 mm, section thickness = 6 mm, gap between sections = 1 mm); (2) T2-weighted imaging (T2WI) and turbo spin-echo (TSE) sequence (TR/TE = 2100 ms/80 ms, flip angle = 90°, image (...truncated)