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Vucevic D, Malis V, Bae WC, Ota H, Oshio K, McDonald MA, Miyazaki M. Visualization of Cerebrospinal Fluid Outflow and Egress along the Nerve Roots of the Lumbar Spine. Bioengineering (Basel) 2024; 11:708. [PMID: 39061790 PMCID: PMC11273714 DOI: 10.3390/bioengineering11070708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2024] [Revised: 07/10/2024] [Accepted: 07/11/2024] [Indexed: 07/28/2024] Open
Abstract
Intrinsic cerebrospinal fluid (CSF) dynamics in the brain have been extensively studied, particularly the egress sites of tagged intrinsic CSF in the meninges. Although spinal CSF recirculates within the central nervous system (CNS), we hypothesized that CSF outflows from the lumbar spinal canal. We aimed to visualize and semi-quantify the outflow using non-contrast MRI techniques. We utilized a 3 Tesla clinical MRI with a 16-channel spine coil, employing time-spatial labeling inversion (Time-SLIP) with tag-on and tag-off acquisitions, T2-weighted coronal 2D fluid-attenuated inversion recovery (FLAIR) and T2-weighted coronal 3D centric ky-kz single-shot FSE (cSSFSE). Images were acquired using time-spatial labeling inversion pulse (Time-SLIP) with tag-on and tag-off acquisitions with varying TI periods. Ten healthy volunteers with no known spinal diseases participated. Variations in tagged CSF outflow were observed across different thoracolumbar nerve root segments in all participants. We quantified CSF outflow at all lumbar levels and the psoas region. There was no significant difference among the ROIs for signal intensity. The tagged CSF outflow from the spinal canal is small but demonstrates egress to surrounding tissues. This finding may pave the way for exploring intrathecal drug delivery, understanding of CSF-related pathologies and its potential as a biomarker for peripheral neuropathy and radiculopathy.
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Affiliation(s)
- Diana Vucevic
- Department of Radiology, University of California San Diego, La Jolla, CA 92093, USA; (D.V.); (V.M.); (W.C.B.); (M.A.M.)
| | - Vadim Malis
- Department of Radiology, University of California San Diego, La Jolla, CA 92093, USA; (D.V.); (V.M.); (W.C.B.); (M.A.M.)
| | - Won C. Bae
- Department of Radiology, University of California San Diego, La Jolla, CA 92093, USA; (D.V.); (V.M.); (W.C.B.); (M.A.M.)
- Department of Radiology, VA San Diego Healthcare System, San Diego, CA 92161, USA
| | - Hideki Ota
- Department of Radiology, Tohoku University, Sendai 980-8576, Miyagi, Japan;
| | - Koichi Oshio
- Department of Radiology, Juntendo University, Tokyo 113-8421, Japan;
| | - Marin A. McDonald
- Department of Radiology, University of California San Diego, La Jolla, CA 92093, USA; (D.V.); (V.M.); (W.C.B.); (M.A.M.)
| | - Mitsue Miyazaki
- Department of Radiology, University of California San Diego, La Jolla, CA 92093, USA; (D.V.); (V.M.); (W.C.B.); (M.A.M.)
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Shlobin NA, Staple BL, Sclafani M, Harter DH. The Glymphatic System and Subarachnoid Lymphatic-Like Membrane: Recent Developments in Cerebrospinal Fluid Research. World Neurosurg 2024; 190:147-156. [PMID: 39002777 DOI: 10.1016/j.wneu.2024.07.062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Revised: 07/05/2024] [Accepted: 07/06/2024] [Indexed: 07/15/2024]
Abstract
BACKGROUND Cerebrospinal fluid (CSF) circulates throughout the ventricles, cranial and spinal subarachnoid spaces, and central spinal cord canal. CSF protects the central nervous system through mechanical cushioning, regulation of intracranial pressure, regulation of metabolic homeostasis, and provision of nutrients. Recently, investigators have characterized the glial-lymphatic (glymphatic) system, the analog of the lymphatic system in the central nervous system, and described a fourth meningeal layer; the subarachnoid lymphatic-like membrane (SLYM)relevant to the CSF. METHODS A narrative review was conducted. RESULTS In this review, we summarize these advances. We describe the development of the original model, controversies, a revised model, and a new conceptual framework. We characterize the biological functions, influence of sleep-wake cycles, and effect of aging with relevance to the glymphatic system. We highlight the role of the glymphatic system in Alzheimer's disease, idiopathic normal pressure hydrocephalus, ischemic stroke, subarachnoid hemorrhage, and traumatic brain injury. Next, we characterize the structure and role of the SLYM. Finally, we explore the relevance of the glymphatic system and SLYM to neurosurgery. CONCLUSIONS This manuscript will inform clinicians and scientists regarding preclinical and translational advances in the understanding of the structure, dynamics, and function of the CSF.
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Affiliation(s)
- Nathan A Shlobin
- Department of Neurological Surgery, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA.
| | - Brandon L Staple
- College of Medicine, University of Nebraska, Omaha, Nebraska, USA
| | | | - David H Harter
- Department of Neurosurgery, NYU Langone, New York, New York, USA
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Jaafar N, Alsop DC. Arterial Spin Labeling: Key Concepts and Progress Towards Use as a Clinical Tool. Magn Reson Med Sci 2024; 23:352-366. [PMID: 38880616 PMCID: PMC11234948 DOI: 10.2463/mrms.rev.2024-0013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Accepted: 05/15/2024] [Indexed: 06/18/2024] Open
Abstract
Arterial spin labeling (ASL), a non-invasive MRI technique, has emerged as a valuable tool for researchers that can measure blood flow and related parameters. This review aims to provide a qualitative overview of the technical principles and recent developments in ASL and to highlight its potential clinical applications. A growing literature demonstrates impressive ASL sensitivity to a range of neuropathologies and treatment responses. Despite its potential, challenges persist in the translation of ASL to widespread clinical use, including the lack of standardization and the limited availability of comprehensive training. As experience with ASL continues to grow, the final stage of translation will require moving beyond single site observational studies to multi-site experience and measurement of the added contribution of ASL to patient care and outcomes.
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Affiliation(s)
- Narjes Jaafar
- Department of Radiology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA
| | - David C. Alsop
- Department of Radiology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA
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Bae WC, Malis V, Vucevic D, Yamamoto A, Nakamura K, Lane J, Miyazaki M. Non-contrast MRI of micro-vascularity of the feet and toes. Jpn J Radiol 2024; 42:785-797. [PMID: 38536557 DOI: 10.1007/s11604-024-01553-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Accepted: 02/28/2024] [Indexed: 07/03/2024]
Abstract
PURPOSE This study aimed to develop novel non-contrast MR perfusion techniques for assessing micro-vascularity of the foot in human subjects. METHODS All experiments were performed on a clinical 3 T scanner using arterial spin labeling (ASL). Seven healthy subjects (30-72 years old, 5 males and 2 females) were enrolled and bilateral feet were imaged with tag-on and tag-off alternating inversion recovery spin labeling for determining micro-vascularity. We compared an ASL technique with 1-tag against 4-tag pulses. For perfusion, we determined signal increase ratio (SIR) at varying inversion times (TI) from 0.5 to 2 s. SIR versus TI data were fit to determine perfusion metrics of peak height (PH), time to peak (TTP), full width at half maximum (FWHM), area under the curve (AUC), and apparent blood flow (aBF) in the distal foot and individual toes. Using analysis of variance (ANOVA), effects of tag pulse and region of interest (ROI) on the mean perfusion metrics were assessed. In addition, a 4-tag pulse perfusion experiment was performed on patients with peripheral artery disease (PAD) and Raynaud's disease. RESULTS Using our MR perfusion techniques, SIR versus TI data showed well-defined leading and trailing edges, with a peak near TI of 0.75-1.0 s and subsiding quickly to near zero by TI of 2 s, particularly when 4-tag pulses were used. When imaged with 4-tag pulse, we found significantly greater values in perfusion metrics, as compared to 1-tag pulse. The patients with PAD and Raynaud's disease showed a reduced or scattered perfusion curves compared to the healthy control. CONCLUSION MR perfusion imaging of the distal foot shows greater SIR and perfusion metrics with the 4-tag pulse compared to the 1-tag pulse technique. This will likely benefit those with low perfusion due to aging, PAD, diabetic foot, and other vascular diseases.
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Affiliation(s)
- Won C Bae
- Department of Radiology, University of California-San Diego, La Jolla, CA, USA
- Department of Radiology, VA San Diego Healthcare System, San Diego, CA, USA
| | - Vadim Malis
- Department of Radiology, University of California-San Diego, La Jolla, CA, USA
| | - Diana Vucevic
- Department of Radiology, University of California-San Diego, La Jolla, CA, USA
| | - Asako Yamamoto
- Department of Radiology, Teikyo University, Tokyo, Japan
| | | | - John Lane
- Department of Surgery, University of California-San Diego, La Jolla, CA, USA
| | - Mitsue Miyazaki
- Department of Radiology, University of California-San Diego, La Jolla, CA, USA.
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Ota H, Morita Y, Vucevic D, Higuchi S, Takagi H, Kutsuna H, Yamashita Y, Kim P, Miyazaki M. Motion robust coronary MR angiography using zigzag centric ky-kz trajectory and high-resolution deep learning reconstruction. MAGMA (NEW YORK, N.Y.) 2024:10.1007/s10334-024-01172-9. [PMID: 38916681 DOI: 10.1007/s10334-024-01172-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Revised: 04/28/2024] [Accepted: 05/27/2024] [Indexed: 06/26/2024]
Abstract
PURPOSE To develop a new MR coronary angiography (MRCA) technique by employing a zigzag fan-shaped centric ky-kz k-space trajectory combined with high-resolution deep learning reconstruction (HR-DLR). METHODS All imaging data were acquired from 12 healthy subjects and 2 patients using two clinical 3-T MR imagers, with institutional review board approval. Ten healthy subjects underwent both standard 3D fast gradient echo (sFGE) and centric ky-kz k-space trajectory FGE (cFGE) acquisitions to compare the scan time and image quality. Quantitative measures were also performed for signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) as well as sharpness of the vessel. Furthermore, the feasibility of the proposed cFGE sequence was assessed in two patients. For assessing the feasibility of the centric ky-kz trajectory, the navigator-echo window of a 30-mm threshold was applied in cFGE, whereas sFGE was applied using a standard 5-mm threshold. Image quality of MRCA using cFGE with HR-DLR and sFGE without HR-DLR was scored in a 5-point scale (non-diagnostic = 1, fair = 2, moderate = 3, good = 4, and excellent = 5). Image evaluation of cFGE, applying HR-DLR, was compared with sFGE without HR-DLR. Friedman test, Wilcoxon signed-rank test, or paired t tests were performed for the comparison of related variables. RESULTS The actual MRCA scan time of cFGE with a 30-mm threshold was acquired in less than 5 min, achieving nearly 100% efficiency, showcasing its expeditious and robustness. In contrast, sFGE was acquired with a 5-mm threshold and had an average scan time of approximately 15 min. Overall image quality for MRCA was scored 3.3 for sFGE and 2.7 for cFGE without HR-DLR but increased to 3.6 for cFGE with HR-DLR and (p < 0.05). The clinical result of patients obtained within 5 min showed good quality images in both patients, even with a stent, without artifacts. Quantitative measures of SNR, CNR, and sharpness of vessel presented higher in cFGE with HR-DLR. CONCLUSION Our findings demonstrate a robust, time-efficient solution for high-quality MRCA, enhancing patient comfort and increasing clinical throughput.
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Affiliation(s)
- Hideki Ota
- Department of Advanced Radiological Imaging Collaborative Research, Graduate School of Medicine, Tohoku University, Sendai, Japan
- Department of Diagnostic Radiology, Tohoku University Hospital, Sendai, Japan
| | - Yoshiaki Morita
- Department of Diagnostic Radiology, Tohoku University Hospital, Sendai, Japan
- Department of Radiology, National Cerebral and Cardiovascular Center, Suita, Osaka, Japan
| | - Diana Vucevic
- Department of Radiology, University of California, San Diego, La Jolla, CA, USA
| | - Satoshi Higuchi
- Department of Diagnostic Radiology, Tohoku University Hospital, Sendai, Japan
| | - Hidenobu Takagi
- Department of Advanced Radiological Imaging Collaborative Research, Graduate School of Medicine, Tohoku University, Sendai, Japan
- Department of Diagnostic Radiology, Tohoku University Hospital, Sendai, Japan
| | | | | | - Paul Kim
- Department of Cardiology, University of California, San Diego, La Jolla, CA, USA
| | - Mitsue Miyazaki
- Department of Radiology, University of California, San Diego, La Jolla, CA, USA.
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Azadian MM, Macedo N, Yu BJ, Fame RM, Airan RD. Ultrasonic cerebrospinal fluid clearance improves outcomes in hemorrhagic brain injury models. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.02.597001. [PMID: 38895304 PMCID: PMC11185536 DOI: 10.1101/2024.06.02.597001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
Impaired clearance of the byproducts of aging and neurologic disease from the brain exacerbates disease progression and severity. We have developed a noninvasive, low intensity transcranial focused ultrasound protocol that facilitates the removal of pathogenic substances from the cerebrospinal fluid (CSF) and the brain interstitium. This protocol clears neurofilament light chain (NfL) - an aging byproduct - in aged mice and clears red blood cells (RBCs) from the central nervous system in two mouse models of hemorrhagic brain injury. Cleared RBCs accumulate in the cervical lymph nodes from both the CSF and interstitial compartments, indicating clearance through meningeal lymphatics. Treating these hemorrhagic brain injury models with this ultrasound protocol reduced neuroinflammatory and neurocytotoxic profiles, improved behavioral outcomes, decreased morbidity and, importantly, increased survival. RBC clearance efficacy was blocked by mechanosensitive channel antagonism and was effective when applied in anesthetized subjects, indicating a mechanosensitive channel mediated mechanism that does not depend on sensory stimulation or a specific neural activity pattern. Notably, this protocol qualifies for an FDA non-significant risk designation given its low intensity, making it readily clinically translatable. Overall, our results demonstrate that this low-intensity transcranial focused ultrasound protocol clears hemorrhage and other harmful substances from the brain via the meningeal lymphatic system, potentially offering a novel therapeutic tool for varied neurologic disorders.
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Affiliation(s)
- Matine M. Azadian
- Department of Radiology, Stanford University School of Medicine, Stanford, CA, United States
| | - Nicholas Macedo
- Department of Radiology, Stanford University School of Medicine, Stanford, CA, United States
| | - Brenda J. Yu
- Department of Radiology, Stanford University School of Medicine, Stanford, CA, United States
| | - Ryann M. Fame
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA, United States
| | - Raag D. Airan
- Department of Radiology, Stanford University School of Medicine, Stanford, CA, United States
- Department of Materials Science and Engineering, Stanford University School of Medicine, Stanford, CA, United States
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, CA, United States
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Miyazaki M, Malis V, Yamamoto A, Kungsamutr J, McEvoy LK, McDonald MA, Bae WC. Physical Exercise Alters Egress Pathways for Intrinsic CSF Outflow: An Investigation Performed with Spin-labeling MR Imaging. Magn Reson Med Sci 2024; 23:171-183. [PMID: 36908171 PMCID: PMC11024710 DOI: 10.2463/mrms.mp.2023-0005] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 02/03/2023] [Indexed: 03/13/2023] Open
Abstract
PURPOSE Cerebrospinal fluid (CSF) clearance is essential for maintaining a healthy brain and cognition by removal of metabolic waste from the central nervous system. Physical exercise has been shown to improve human health; however, the effect of physical exercise on intrinsic CSF outflow in humans remains unexplored. The purpose of this study was to investigate intrinsic CSF outflow pathways and quantitative metrics of healthy individuals with active and sedentary lifestyles. In addition, the effect of exercise was investigated among the sedentary subjects before and after 3 weeks of physical activity. METHODS This study was performed on 18 healthy adults with informed consent, using a clinical 3-Tesla MRI scanner. We classified participants into two groups based on reported time spent sitting per day (active group: < 7 hours sitting per day and sedentary group: ≥ 7 hours sitting per day). To elucidate the effect of exercise, sedentary individuals increased their activity to 3.5 hours for 3 weeks. RESULTS We show that there are two intrinsic CSF egress pathways of the dura mater and lower parasagittal dura (PSD). The adults with an active lifestyle had greater intrinsic CSF outflow metrics than adults with a more sedentary lifestyle. However, after increased physical activity, the sedentary group showed improved CSF outflow metrics. This improvement was particularly notable at the lower PSD, where outflow metrics were highest among the active group. CONCLUSION Our findings describe the relationship between physical activity and intrinsic CSF outflow and show a potential selective outflow pathway with increasing physical activity in the lower PSD pathway, potentially from the perivascular space or cortical venous subpial space.
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Affiliation(s)
- Mitsue Miyazaki
- Department of Radiology, University of California San Diego, La Jolla, CA, USA
| | - Vadim Malis
- Department of Radiology, University of California San Diego, La Jolla, CA, USA
| | - Asako Yamamoto
- Department of Radiology, Teikyo University, Tokyo, Japan
| | - Jirach Kungsamutr
- Department of Bioengineering, University of California San Diego, La Jolla, CA, USA
| | - Linda K. McEvoy
- Department of Radiology, University of California San Diego, La Jolla, CA, USA
- Herbert Wertheim School of Public Health and Human Longevity Science, University of California San Diego, La Jolla, CA, USA
| | - Marin A. McDonald
- Department of Radiology, University of California San Diego, La Jolla, CA, USA
| | - Won C Bae
- Department of Radiology, University of California San Diego, La Jolla, CA, USA
- Department of Radiology, Veterans Affairs Healthcare System, La Jolla, CA, USA
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Dai C, Zhao P, Ding H, Lv H, Qiu X, Tang R, Xu N, Huang Y, Han X, Yang Z, Wang Z. Cerebral Sinus Hemodynamics in Adults Revealed by 4D Flow MRI. J Magn Reson Imaging 2024. [PMID: 38235948 DOI: 10.1002/jmri.29210] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Revised: 12/16/2023] [Accepted: 12/18/2023] [Indexed: 01/19/2024] Open
Abstract
BACKGROUND The hemodynamics of the cerebral sinuses play a vital role in understanding blood flow-related diseases, yet the hemodynamics of the cerebral sinuses in normal adults remains an unresolved issue. PURPOSE To evaluate hemodynamics in the cerebral sinus of adults using 4-dimensional flow MRI (4D Flow MRI). STUDY TYPE Cross-sectional. POPULATION Ninety-nine healthy volunteers (mean age, 42.88 ± 13.16 years old; females/males, 55/44). FIELD STRENGTH/SEQUENCE 3 T/4D Flow MRI. ASSESSMENT The blood flow velocity, average blood flow rate (Q), and vortexes at the superior sagittal sinus (SSS), straight sinus (STS), transverse sinus, sigmoid sinus, and jugular bulb of each volunteer were evaluated by two independent neuroradiologists. The relationship between the total cerebral Q and sex and age was also assessed. Twelve volunteers underwent two scans within a month. STATISTICAL TESTS The intraclass correlation coefficient (ICC) evaluated the inter-observer agreement. Blood flow parameters among volunteers were compared by the independent-sample t-test or Mann-Whitney U test. The multiple linear regression equation was used to evaluate the relationship between total cerebral Q and age and sex. P < 0.05 indicated statistical significance. RESULTS The test-retest and interobserver reliability of average velocity and Q were moderate to high (ICC: 0.54-0.99). Cerebral sinus velocity varied by segment and cardiac cycle. The SSS's velocity and Q increased downstream and Q near torcular herophili was 3.5 times that through the STS. The total cerebral Q decreased by 0.06 mL/s per year (β = -0.06 ± 0.013) and was sex-independent within the group. Vortexes were found in 12.12%, 8.9%, and 59.8% of torcular herophili, transverse-sigmoid junction, and jugular bulb, respectively, and were related to higher upstream flow. DATA CONCLUSION Cerebral sinuses could be measured visually and quantitatively in vivo by 4D Flow MRI, providing a basis for future research on pulsating tinnitus, multiple sclerosis, and other related diseases. EVIDENCE LEVEL 2 TECHNICAL EFFICACY: Stage 1.
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Affiliation(s)
- Chihang Dai
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Pengfei Zhao
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Heyu Ding
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Han Lv
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Xiaoyu Qiu
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Ruowei Tang
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Ning Xu
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Yan Huang
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Xu Han
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Zhenghan Yang
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Zhenchang Wang
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing, China
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Bito Y, Ochi H, Shirase R, Yokohama W, Harada K, Kudo K. Low b-value Diffusion Tensor Imaging to Analyze the Dynamics of Cerebrospinal Fluid: Resolving Intravoxel Pseudorandom Motion into Ordered and Disordered Motions. Magn Reson Med Sci 2023:mp.2023-0081. [PMID: 37899254 DOI: 10.2463/mrms.mp.2023-0081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2023] Open
Abstract
PURPOSE Analysis of cerebrospinal fluid (CSF) dynamics may be beneficial for understanding the mechanisms and diagnosis of several neurological diseases. Low b-value diffusion tensor imaging (low-b DTI) is useful for observing the slow and complex motion of the CSF. Theoretically, a mathematical framework suggests that low-b DTI provides the variance of the pseudorandom motion of the CSF. Furthermore, low-b DTI could provide comprehensive information on fluid dynamics. Accordingly, we proposed an analysis technique that resolves intravoxel pseudorandom motion into ordered (linear) and disordered (random) motions based on the mathematical framework. METHODS The proposed analysis technique helps measure low-b DTI with multiple diffusion times and linearly fits its mean diffusivity (MD) with the diffusion time to obtain two parameters, double-slope Vv and y-intersect Dr, which represent the variance of the velocity distribution of linear motion and the diffusion coefficient of random motion, respectively. Seven healthy subjects were scanned to evaluate the proposed technique and investigate fluid dynamics in several representative ROIs. RESULTS The obtained data showed the validity of the technique, repeatability, and consistency across the subjects in ROIs, such as the lateral ventricle (LV), third ventricle (3V), fourth ventricle (4V), and Sylvian fissure (SF). The obtained parameters Vv and Dr highlighted different characteristics of fluid dynamics in the representative ROIs: low Vv and low Dr in the LV, high Vv and moderate Dr in the 3V, and moderate Vv and moderate Dr in the 4V and SF. CONCLUSION The proposed analysis technique will facilitate a comprehensive investigation of the complex dynamics of the CSF using resolved parameters representing ordered and disordered motions.
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Affiliation(s)
- Yoshitaka Bito
- FUJIFILM Healthcare Corporation
- Department of Diagnostic Imaging, Hokkaido University Graduate School of Medicine
| | - Hisaaki Ochi
- FUJIFILM Healthcare Corporation
- Department of Diagnostic Imaging, Hokkaido University Graduate School of Medicine
| | | | | | - Kuniaki Harada
- Department of Diagnostic Imaging, Hokkaido University Graduate School of Medicine
| | - Kohsuke Kudo
- Department of Diagnostic Imaging, Hokkaido University Graduate School of Medicine
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