Yibao Wang

Differences Between Generalized Q-Sampling Imaging and Diffusion Tensor Imaging in the Preoperative Visualization of the Nerve Fiber Tracts Within Peritumoral Edema in Brain

BACKGROUNDnDiffusion tensor imaging (DTI) tractography enables the in vivo visualization of white matter tracts inside normal brain tissue, which provides the neurosurgeon important information to plan tumor resections. However, DTI is associated with restrictions in the resolution of crossing fibers in the vicinity of the tumor or in edema. We find that generalized q-sampling imaging (GQI) can overcome these difficulties and is advantageous over DTI for the tractography of the fiber bundle in peritumoral edema.nnnOBJECTIVEnTo demonstrate the differences between GQI and DTI in the preoperative mapping of fiber tractography in peritumoral edema of cerebral tumors, and discuss the clinical application of GQI in neurosurgical planning.nnnMETHODSnFive patients with brain tumors underwent 3-T magnetic resonance imaging scans, and the data were reconstructed by DTI and GQI. We adjusted the parameters and compared the differences between DTI and GQI in visualizing the fiber tracts in the peritumoral edema of cerebral tumors.nnnRESULTSnGQI and DTI showed substantial differences in displaying the nerve fibers in the edema surrounding the tumor. The GQI tractography method could fully display existing intact fibers in the edema, whereas the fiber tracts in edema displayed by DTI tractography were incomplete, missing, or ruptured.nnnCONCLUSIONnGQI can visualize the tracts in the peritumoral edema of cerebral tumors better than DTI. Although GQI has many limitations, its future in the preoperative guidance of brain tumor lesions is promising.

Subcomponents and Connectivity of the Inferior Fronto-Occipital Fasciculus Revealed by Diffusion Spectrum Imaging Fiber Tracking

The definitive structure and functional role of the inferior fronto-occipital fasciculus (IFOF) are still controversial. In this study, we aimed to investigate the connectivity, asymmetry, and segmentation patterns of this bundle. High angular diffusion spectrum imaging (DSI) analysis was performed on 10 healthy adults and a 90-subject DSI template (NTU-90 Atlas). In addition, a new tractography approach based on the anatomic subregions and two regions of interest (ROI) was evaluated for the fiber reconstructions. More widespread anterior-posterior connections than previous “standard” definition of the IFOF were found. This distinct pathway demonstrated a greater inter-subjects connective variability with a maximum of 40% overlap in its central part. The statistical results revealed no asymmetry between the left and right hemispheres and no significant differences existed in distributions of the IFOF according to sex. In addition, five subcomponents within the IFOF were identified according to the frontal areas of originations. As the subcomponents passed through the anterior floor of the external capsule, the fibers radiated to the posterior terminations. The most common connection patterns of the subcomponents were as follows: IFOF-I, from frontal polar cortex to occipital pole, inferior occipital lobe, middle occipital lobe, superior occipital lobe, and pericalcarine; IFOF-II, from orbito-frontal cortex to occipital pole, inferior occipital lobe, middle occipital lobe, superior occipital lobe, and pericalcarine; IFOF-III, from inferior frontal gyrus to inferior occipital lobe, middle occipital lobe, superior occipital lobe, occipital pole, and pericalcarine; IFOF-IV, from middle frontal gyrus to occipital pole, and inferior occipital lobe; IFOF-V, from superior frontal gyrus to occipital pole, inferior occipital lobe, and middle occipital lobe. Our work demonstrates the feasibility of high resolution diffusion tensor tractography with sufficient sensitivity to elucidate more anatomical details of the IFOF. And we provides a new framework for subdividing the IFOF for better understanding its functional role in the human brain.

Tracing short connections of the temporo-parieto-occipital region in the human brain using diffusion spectrum imaging and fiber dissection

The temporo-parieto-occipital (TPO) junction plays a unique role in human high-level neurological functions. Long-range fibers from and to this area have been described in detail but little is known about short TPO tracts mediating local connectivity. In this study, we performed high angular diffusion spectrum imaging (DSI) analyses to visualize the short TPO connections in the human brain. Fiber tracking was conducted on a subject-specific approach (10 subjects) and a template of 90 subjects (NTU-90 Atlas). Three tracts were identified: posterior segment of the superior longitudinal fasciculus (SLF-V), connecting the posterior part of the middle and inferior temporal gyri with the angular gyrus and supramarginal gyrus, vertical occipital fasciculus (VOF), connecting the inferior parietal with the lower temporal and occipital lobe, and a novel temporo-parietal (TP) connection, interconnecting the inferior temporal gyrus, middle temporal gyrus and fusiform gyrus, and inferior occipital lobe with the superior parietal lobe. These studies were complemented by fiber dissection techniques. It is the first study that demonstrated the trajectory and connectivity of the VOF using fiber dissection, as well as displayed the spatial relationship of the SLF-V with the cortex and the adjacent fiber bundles on one dissecting hemisphere. By providing a more accurate and detailed description of the local connectivity of the TPO junction, our findings help to develop new insights into its functional role in the human brain.

Bradykinin regulates the expression of claudin-5 in brain microvascular endothelial cells via calcium-induced calcium release

To investigate the mechanism underlying the regulation of claudin‐5, a tight junction protein that participates primarily in the constitution of the blood–brain barrier by bradykinin (BK), we established a primary culture of rat brain microvascular endothelial cells (BMECs). BMECs were treated with 10−5 M BK, and changes in the intracellular Ca2+ levels were measured by using the sensitive fluorescent dye fluo‐3; the expression and distribution of claudin‐5 were investigated by immunocytochemistry and Western blot analyses. We did not detect any expression of bradykinin B2 receptors in the BMECs or freshly isolated rat brain microvessels. We found that 10−5 M BK triggered Ca2+ transients in BMECs, and further investigations revealed that inositol 1,4,5‐trisphosphate receptors (IP3Rs) and ryanodine receptors (RyRs) on the endoplasmic reticulum (ER) were responsible for the Ca2+ fluctuation. Consequently, these intracellular Ca2+ changes that occur in response to BK application were identified as Ca2+‐induced Ca2+ release (CICR). Immunocytochemistry and Western blot results demonstrated that 10−5 M BK could cause the internalization and a decrease in the expression of claudin‐5; agonists of IP3Rs and RyRs, such as IP3 and caffeine, enhanced the BK‐induced downregulation of claudin‐5, whereas antagonists of IP3Rs and RyRs, such as 2‐APB and ryanodine, abrogated BKs effect on claudin‐5. In conclusion, the BK‐induced CICR in primary culture BMECs might be the mechanism by which BK modulates claudin‐5.

Segmentation of the Cingulum Bundle in the Human Brain: A New Perspective Based on DSI Tractography and Fiber Dissection Study

The cingulum bundle (CB) is a critical white matter fiber tract in the brain, which forms connections between the frontal lobe, parietal lobe and temporal lobe. In non-human primates, the CB is actually divided into distinct subcomponents on the basis of corticocortical connections. However, at present, no study has verified similar distinct subdivisions in the human brain. In this study, we reconstructed these distinct subdivisions in the human brain, and determined their exact cortical connections using high definition fiber tracking (HDFT) technique on 10 healthy adults and a 488-subject template from the Human Connectome Project (HCP-488). Fiber dissections were performed to verify tractography results. Five CB segments were identified. CB-I ran from the subrostral areas to the precuneus and splenium, encircling the corpus callosum (CC). CB-II arched around the splenium and extended anteriorly above the CC to the medial aspect of the superior frontal gyrus (SFG). CB-III connected the superior parietal lobule (SPL) and precuneus with the medial aspect of the SFG. CB-IV was a relatively minor subcomponent from the SPL and precuneus to the frontal region. CB-V, the para-hippocampal cingulum, stemmed from the medial temporal lobe and fanned out to the occipital lobes. Our findings not only provide a more accurate and detailed description on the associated architecture of the subcomponents within the CB, but also offer new insights into the functional role of the CB in the human brain.

Microsurgery for the treatment of primary malignant intracranial melanoma: A surgical series and literature review

BACKGROUNDnPrimary malignant intracranial melanomas are rare tumors of the central nervous system. These tumors are highly malignant and are associated with poor prognosis. The field of neurosurgery has struggled with the diagnosis and treatment of these tumors.nnnMETHODSnIn this study, we present a surgical series of eight patients with primary malignant intracranial melanomas and retrospectively analyze the clinical features, imaging findings, pathological features and prognoses of these patients.nnnRESULTSnAll patients underwent microsurgery. Total and subtotal resection of the tumor was achieved in six and two patients, respectively. Of the eight patients, seven showed improvement while one remained the same at time of discharge. There was no neurosurgical deterioration. Radiotherapy was conducted in six patients after operation. The average follow-up duration was 13.8 months (range = 9-26 months). During the follow-up period, three patients died from this disease. One patient suffered from recurrence at the 16th month and underwent second surgery. The other patients were still alive with no evidence of tumor recurrence.nnnCONCLUSIONnMicrosurgery and radiotherapy should be the first line managements for patients with primary malignant intracranial melanomas. Improvements in chemotherapy, immunotherapy and targeted therapies may provide more effective treatments for malignant intracranial melanomas.

The uncinate fasciculus as observed using diffusion spectrum imaging in the human brain

IntroductionThe definitive structure and comprehensive role of the uncinate fasciculus (UF) are still obscure. We aimed to map the human UF white matter tractography and investigate the asymmetry, connectivity, and segmentation of the UF.MethodsSubcomponents of the UF were analyzed in 9 normal subjects and a 30-subject diffusion spectrum imaging (DSI) template (CMU-30). DSI and microdissection were performed to explore the tractography of the UF.ResultsBoth methods revealed that it connects the anterior part of the temporal lobe (superior temporal gyrus and temporal pole) with the inferior frontal cortex and the orbitofrontal cortex. The UF starts at the temporal gyrus, runs inferiorly to the inferior frontal occipital fasciculus and splits into two branches, terminating in the ventrolateral frontal cortex and the rostral middle frontal cortex. Our study showed that the cortical areas of termination in the frontal lobe of the UF are the pars triangularis and pars orbitalis. The relative volume of the UF in both hemispheres was calculated. An independent t test was used to determine variances in the value of tract volume between the left and right hemispheres. The volume and the length showed a significant statistical difference in the total volume of the UF. We suggest the UF is leftward asymmetry.ConclusionsThe two parts of the UF were divided, but the conclusion is not consistent with the previous published articles which have shown that the UF is segmented into three parts. Our research facilitates a better understanding of the UF.

Microsurgical treatment of meningeal malignant melanoma accompanied by nevus of Ota: two case reports and a literature review.

Introduction Primary malignant intracranial melanomas are rare lesions of the central nervous system [1–5], whereas those arising from meningeal and accompanied by nevus of Ota are even more rare. In this study, we present two cases of primary dural melanomas with a nevus of Ota and discussed the diagnostic and therapeutic strategies for treating these unusual lesions by reviewing the relevant literature.

Microsurgical management of dumbbell C1 and C2 schwannomas via the far lateral approach

Dumbbell C1 and C2 schwannomas are rare and have a distinctive presentation and anatomical features. To study the clinical characteristics of these tumors, we reviewed the microsurgical management of 18 patients with dumbbell C1 and C2 schwannomas by the far lateral approach. Data regarding clinical manifestations, radiological findings and surgical results were analyzed retrospectively. Total and subtotal resection of the tumor was achieved in 15 and three patients, respectively. At the time of discharge, 12 patients showed improvement while five patients remained the same. The average follow-up duration was 43 months (range = 3-110 months); six of seven patients had recovery from local pain or numbness. With the exception of one patient with hemiplegia or hemiparesthesia preoperatively, all patients recovered within 6 months postoperatively. The far lateral approach offers adequate exposure and access with minimal neural manipulation for treating dumbbell C1 and C2 schwannomas, and is considered the preferred surgical approach for resection of these tumors located ventrally or ventrolaterally to the first two cervical vertebrae.

Clival metastasis of renal clear cell carcinoma: Case report and literature review

The clivus is an atypical metastatic site for renal clear cell carcinoma (RCCC). Here we report a 54 year old man with acute cavernous sinus syndrome. Brain magnetic resonance imaging identified a clival-based lesion with associated bony erosion. The patient underwent endoscopic endonasal biopsy and partial resection of the clival mass. Because histologic examination of the resected specimen resulted in a diagnosis of RCCC, contrast-enhanced computed tomography scan of the abdomen was performed and showed an enhanced left renal mass. The patient subsequently underwent laparoscopic left radical nephrectomy and gamma knife was planned for the residual clival lesion. We also retrospectively reviewed available published reports on clival metastases, specifically those from RCCC, since 1990.