1
|
Maki Y, Takayama M, Okawa T, Goda A, Miyakoshi A. Diffusion tensor imaging combined with the dual-echo steady-state (DESS) protocol for the evaluation of the median nerve in the carpal tunnel: A preliminary study. Surg Neurol Int 2024; 15:110. [PMID: 38628509 PMCID: PMC11021107 DOI: 10.25259/sni_156_2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2024] [Accepted: 03/08/2024] [Indexed: 04/19/2024] Open
Abstract
Background Carpal tunnel syndrome (CTS) is diagnosed based on neurological, electrophysiology, and radiological findings. Due to the technical development of magnetic resonance imaging (MRI), the median nerve is evaluated with several MRI protocols. However, diffusion tensor imaging (DTI) combined with a dual-echo steady-state (DESS) protocol is not frequently used to evaluate the median nerve of CTS. This study aimed to evaluate the median nerve in the carpal tunnel using DTI combined with a DESS protocol. Methods Five healthy volunteers and seven patients with CTS were enrolled. The patients underwent MRI for CTS pre- and post-operatively. The median nerve was evaluated using a 3-T MRI scanner. The parameters of the DESS protocol were as follows: Repetition time (TR)/echo time (TE) = 10.83/3.32 ms, slice thickness = 0.45 mm, field of view (FoV) = 350 × 253 × 350 mm, and 3D voxel size = 0.5 × 0.5 ×0.4 mm. The parameters of the DTI sequence were as follows: TR/TE = 4000/86 ms, slice thickness = 3 mm, FoV = 160 × 993 × 90 mm, 3D voxel size = 1.2 × 1.2 ×3.0 mm, and b value = 0.1000 s/mm2. The apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values of the median nerve were statistically analyzed. Statistical significance was set at P< 0.05. Results The FA value of healthy volunteers was 0.576 ± 0.058, while those of the patients were 0.357 ± 0.094 and 0.395 ± 0.062 pre-and post-operatively, respectively. Statistically significant differences were identified between the FA values of healthy volunteers and pre-operative/post-operative patients. The ADC values of healthy volunteers and pre-operative patients were 0.931 ± 0.096 and 1.26 ± 0.282 (10-3 mm2/s), respectively (P< 0.05). Conclusion This MRI protocol may be useful for evaluating the median nerve in the carpal tunnel.
Collapse
Affiliation(s)
- Yoshinori Maki
- Department of Neurosurgery, Hikone Chuo Hospital, Hikone, Japan
| | | | - Tsuyoshi Okawa
- Department of Radiology, Fujieda Municipal General Hospital, Fujieda, Japan
| | - Akio Goda
- Department of Physical Therapy, Faculty of Health and Medical Sciences, Hokuriku University, Kanazawa, Japan
| | - Akinori Miyakoshi
- Department of Neurosurgery, Shizuoka General Hospital, Shizuoka, Japan
| |
Collapse
|
2
|
Schmid AB, Ridgway L, Hailey L, Tachrount M, Probert F, Martin KR, Scott W, Crombez G, Price C, Robinson C, Koushesh S, Ather S, Tampin B, Barbero M, Nanz D, Clare S, Fairbank J, Baskozos G. Factors predicting the transition from acute to persistent pain in people with 'sciatica': the FORECAST longitudinal prognostic factor cohort study protocol. BMJ Open 2023; 13:e072832. [PMID: 37019481 PMCID: PMC10111910 DOI: 10.1136/bmjopen-2023-072832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 03/15/2023] [Indexed: 04/07/2023] Open
Abstract
INTRODUCTION Sciatica is a common condition and is associated with higher levels of pain, disability, poorer quality of life, and increased use of health resources compared with low back pain alone. Although many patients recover, a third develop persistent sciatica symptoms. It remains unclear, why some patients develop persistent sciatica as none of the traditionally considered clinical parameters (eg, symptom severity, routine MRI) are consistent prognostic factors.The FORECAST study (factors predicting the transition from acute to persistent pain in people with 'sciatica') will take a different approach by exploring mechanism-based subgroups in patients with sciatica and investigate whether a mechanism-based approach can identify factors that predict pain persistence in patients with sciatica. METHODS AND ANALYSIS We will perform a prospective longitudinal cohort study including 180 people with acute/subacute sciatica. N=168 healthy participants will provide normative data. A detailed set of variables will be assessed within 3 months after sciatica onset. This will include self-reported sensory and psychosocial profiles, quantitative sensory testing, blood inflammatory markers and advanced neuroimaging. We will determine outcome with the Sciatica Bothersomeness Index and a Numerical Pain Rating Scale for leg pain severity at 3 and 12 months.We will use principal component analysis followed by clustering methods to identify subgroups. Univariate associations and machine learning methods optimised for high dimensional small data sets will be used to identify the most powerful predictors and model selection/accuracy.The results will provide crucial information about the pathophysiological drivers of sciatica symptoms and may identify prognostic factors of pain persistence. ETHICS AND DISSEMINATION The FORECAST study has received ethical approval (South Central Oxford C, 18/SC/0263). The dissemination strategy will be guided by our patient and public engagement activities and will include peer-reviewed publications, conference presentations, social media and podcasts. TRIAL REGISTRATION NUMBER ISRCTN18170726; Pre-results.
Collapse
Affiliation(s)
- Annina B Schmid
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, Oxfordshire, UK
- Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford, Oxfordshire, UK
| | - Lucy Ridgway
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, Oxfordshire, UK
| | - Louise Hailey
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, Oxfordshire, UK
- Nuffield Department of Orthopaedics Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, Oxfordshire, UK
| | - Mohamed Tachrount
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, Oxfordshire, UK
- Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford, Oxfordshire, UK
| | - Fay Probert
- Department of Chemistry, University of Oxford, Oxford, Oxfordshire, UK
| | - Kathryn R Martin
- Academic Primary Care, Institute of Applied Health Sciences, School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen, UK
- Aberdeen Centre for Arhtritis and Musculoskeletal Health, School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen, UK
| | - Whitney Scott
- Health Psychology Section, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
- INPUT Pain Management Unit, Guy's and St Thomas' NHS Foundation Trust, London, UK
| | - Geert Crombez
- Department of Experimental Clinical and Health Psychology, University of Ghent, Gent, Belgium
| | - Christine Price
- Patient partner FORECAST study, Oxford University, Oxford, UK
| | - Claire Robinson
- Patient partner FORECAST study, Oxford University, Oxford, UK
| | - Soraya Koushesh
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, Oxfordshire, UK
| | - Sarim Ather
- Department of Radiology, Oxford University Hospitals NHS Foundation Trust, Oxford, Oxfordshire, UK
| | - Brigitte Tampin
- Department of Physiotherapy, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia
- Curtin School of Allied Health, Faculty of Health Sciences, Curtin University, Perth, Western Australia, Australia
- Faculty of Business and Social Sciences, University of Applied Sciences, Osnabrueck, Germany
| | - Marco Barbero
- Rehabilitation Research Laboratory 2rLab, Department of Business Economics Health and Social Care, University of Applied Sciences and Arts of Southern Switzerland, Manno, Ticino, Switzerland
| | - Daniel Nanz
- Swiss Center for Musculoskeletal Imaging, Balgrist Campus AG, Zurich, Zurich, Switzerland
- Medical Faculty, University of Zurich, Zurich, Zurich, Switzerland
| | - Stuart Clare
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, Oxfordshire, UK
- Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford, Oxfordshire, UK
| | - Jeremy Fairbank
- Nuffield Department of Orthopaedics Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, Oxfordshire, UK
| | - Georgios Baskozos
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, Oxfordshire, UK
| |
Collapse
|
3
|
Evans AG, Morgan MD, Aiken BA, Assi PE, Joseph JT, Kesayan T, Mioton LM, Esteve IVM, Hill JB, Thayer WP, Al Kassis S. Can Diffusion Tensor Imaging Apparent Diffusion Coefficient Diagnose Carpal Tunnel Syndrome? A Systematic Review and Meta-Analysis. Hand (N Y) 2023; 18:91S-99S. [PMID: 35695339 PMCID: PMC9896277 DOI: 10.1177/15589447221096706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Magnetic resonance diffusion tensor imaging (DTI) can detect microstructural changes in peripheral nerves. Studies have reported that the median nerve apparent diffusion coefficient (ADC), a quantification of water molecule diffusion direction, is sensitive in diagnosing carpal tunnel syndrome (CTS). Five databases were searched for studies using ADC to investigate CTS. Apparent diffusion coefficient (measured in mm2/s) were pooled in random-effects meta-analyses. Twenty-two studies met criteria yielding 592 patients with CTS and 414 controls. Median nerve ADC were measured at the level of the distal radioulnar joint (CTS ADC: 1.11, 95% CI: 1.07-1.15, I2 = 54%; control ADC: 1.04, 95% CI: 1.01-1.07, I2 = 57%), pisiform (CTS ADC: 1.39, 95% CI: 1.37-1.42, I2 = 0%; control ADC: 1.27, 95% CI: 1.23-1.31, I2 = 59%), hamate (CTS ADC: 1.40, 95% CI: 1.36-1.43, I2 = 58%; control ADC: 1.27, 95% CI: 1.25-1.28, I2 = 47%), and as an combination of several measurements (CTS ADC: 1.40, 95% CI: 1.37-1.47, I2 = 100%; control ADC: 1.39, 95% CI: 1.24-1.53, I2 = 100%). Median nerve ADC is decreased in individuals with CTS compared to controls at the levels of the hamate and pisiform. ADC cut-offs to diagnose CTS should be established according to these anatomic levels and can be improved through additional studies that include use of a wrist coil.
Collapse
Affiliation(s)
- Adam G. Evans
- Meharry Medical College,
Nashville, TN, USA
- Vanderbilt University Medical
Center, Nashville, TN, USA
| | | | | | | | | | - Tigran Kesayan
- Vanderbilt University Medical
Center, Nashville, TN, USA
| | | | | | | | | | | |
Collapse
|
4
|
Ridehalgh C, Fundaun J, Bremner S, Cercignani M, Young R, Trivedy C, Novak A, Greening J, Schmid A, Dilley A. Does peripheral neuroinflammation predict chronicity following whiplash injury? Protocol for a prospective cohort study. BMJ Open 2022; 12:e066021. [PMID: 36521884 PMCID: PMC9756191 DOI: 10.1136/bmjopen-2022-066021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 11/21/2022] [Indexed: 12/23/2022] Open
Abstract
INTRODUCTION Whiplash-associated disorder grade 2 (WAD2) is characterised by musculoskeletal pain/tenderness but no apparent nerve injury. However, studies have found clinical features indicative of neuropathy and neuropathic pain. These studies may indicate peripheral nerve inflammation, since preclinical neuritis models found mechanical sensitivity in inflamed, intact nociceptors. The primary aim of this study is to establish the contribution of peripheral neuroinflammation to WAD2 and its role in prognosis. Participants will be invited to participate in a sub-study investigating the contribution of cutaneous small fibre pathology to WAD2. METHODS AND ANALYSIS 115 participants within 1 month following whiplash injury and 34 healthy control participants will be recruited and complete validated questionnaires for pain, function and psychological factors. Data collection will take place at the Universities of Sussex and Oxford, UK. Clinical examination, quantitative sensory testing and blood samples will be undertaken. MRI scans using T2-weighted and diffusion tensor images of the brachial plexus and wrist will determine nerve inflammation and nerve structural changes. Skin biopsies from a substudy will determine structural integrity of dermal and intraepidermal nerve fibres. At 6 months, we will evaluate recovery using Neck Disability Index and a self-rated global recovery question and repeat the outcome measures. Regression analysis will identify differences in MRI parameters, clinical tests and skin biopsies between participants with WAD2 and age/gender-matched controls. Linear and logistic regression analyses will assess if nerve inflammation (MRI parameters) predicts poor outcome. Mixed effects modelling will compare MRI and clinical measures between recovered and non-recovered participants over time. ETHICS AND DISSEMINATION Ethical approval was received from London-Brighton and Sussex Research Ethics Committee (20/PR/0625) and South Central-Oxford C Ethics Committee (18/SC/0263). Written informed consent will be obtained from participants prior to participation in the study. Results will be disseminated through publications in peer-reviewed journals, presentations at national/international conferences and social media. TRIAL REGISTRATION NUMBER NCT04940923.
Collapse
Affiliation(s)
- Colette Ridehalgh
- Department of Neuroscience, Brighton and Sussex Medical School, Brighton, UK
- School of Sport and Health Sciences, University of Brighton, Eastbourne, UK
| | - Joel Fundaun
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Stephen Bremner
- Department of Primary Care and Public Health, Brighton and Sussex Medical School, Brighton, UK
| | - Mara Cercignani
- Cardiff University Brain Research Imaging Centre, Cardiff University, Cardiff, UK
| | - Rupert Young
- School of engineering and informatics, University of Sussex, Brighton, UK
| | - Chetan Trivedy
- Emergency Departments, University Hospitals Sussex NHS Foundation Trust, Brighton, UK
- Queen Mary University of London, London, UK
| | - Alex Novak
- Emergency Medicine Research Oxford, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Jane Greening
- Department of Neuroscience, Brighton and Sussex Medical School, Brighton, UK
| | - Annina Schmid
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Andrew Dilley
- Department of Neuroscience, Brighton and Sussex Medical School, Brighton, UK
| |
Collapse
|
5
|
Rojoa D, Raheman F, Rassam J, Wade RG. Meta-analysis of the normal diffusion tensor imaging values of the median nerve and how they change in carpal tunnel syndrome. Sci Rep 2021; 11:20935. [PMID: 34686721 PMCID: PMC8536657 DOI: 10.1038/s41598-021-00353-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 10/05/2021] [Indexed: 02/07/2023] Open
Abstract
Carpal tunnel syndrome (CTS) leads to distortion of axonal architecture, demyelination and fibrosis within the median nerve. Diffusion tensor imaging (DTI) characterises tissue microstructure and generates reproducible proxy measures of nerve 'health' which are sensitive to myelination, axon diameter, fiber density and organisation. This meta-analysis summarises the normal DTI values of the median nerve, and how they change in CTS. This systematic review included studies reporting DTI of the median nerve at the level of the wrist in adults. The primary outcome was to determine the normal fractional anisotropy (FA) and mean diffusivity (MD) of the median nerve. Secondarily, we show how the FA and MD differ between asymptomatic adults and patients with CTS, and how these differences are independent of the acquisition methods. We included 32 studies of 2643 wrists, belonging to 1575 asymptomatic adults and 1068 patients with CTS. The normal FA was 0.58 (95% CI 0.56, 0.59) and the normal MD was 1.138 × 10-3 mm2/s (95% CI 1.101, 1.174). Patients with CTS had a significantly lower FA than controls (mean difference 0.12 [95% CI 0.09, 0.16]). Similarly, the median nerve of patients with CTS had a significantly higher mean diffusivity (mean difference 0.16 × 10-3 mm2/s [95% CI 0.05, 0.27]). The differences were independent of experimental factors. We provide summary estimates of the normal FA and MD of the median nerve in asymptomatic adults. Furthermore, we show that diffusion throughout the length of the median nerve becomes more isotropic in patients with CTS.
Collapse
Affiliation(s)
- Djamila Rojoa
- grid.419248.20000 0004 0400 6485Department of Plastic and Reconstructive Surgery, Leicester Royal Infirmary, Leicester, UK
| | - Firas Raheman
- grid.419248.20000 0004 0400 6485Department of Plastic and Reconstructive Surgery, Leicester Royal Infirmary, Leicester, UK
| | - Joseph Rassam
- grid.419248.20000 0004 0400 6485Department of Plastic and Reconstructive Surgery, Leicester Royal Infirmary, Leicester, UK
| | - Ryckie G. Wade
- grid.415967.80000 0000 9965 1030Department of Plastic and Reconstructive Surgery, Leeds Teaching Hospitals Trust, Leeds, UK ,grid.9909.90000 0004 1936 8403Leeds Institute for Medical Research, Advanced Imaging Centre, University of Leeds, Leeds, LS1 3EX UK
| |
Collapse
|
6
|
Evans MC, Wade C, Hohenschurz-Schmidt D, Lally P, Ugwudike A, Shah K, Bangerter N, Sharp DJ, Rice ASC. Magnetic Resonance Imaging as a Biomarker in Diabetic and HIV-Associated Peripheral Neuropathy: A Systematic Review-Based Narrative. Front Neurosci 2021; 15:727311. [PMID: 34621152 PMCID: PMC8490874 DOI: 10.3389/fnins.2021.727311] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 08/17/2021] [Indexed: 12/18/2022] Open
Abstract
Background: Peripheral neuropathy can be caused by diabetes mellitus and HIV infection, and often leaves patients with treatment-resistant neuropathic pain. To better treat this condition, we need greater understanding of the pathogenesis, as well as objective biomarkers to predict treatment response. Magnetic resonance imaging (MRI) has a firm place as a biomarker for diseases of the central nervous system (CNS), but until recently has had little role for disease of the peripheral nervous system. Objectives: To review the current state-of-the-art of peripheral nerve MRI in diabetic and HIV symmetrical polyneuropathy. We used systematic literature search methods to identify all studies currently published, using this as a basis for a narrative review to discuss major findings in the literature. We also assessed risk of bias, as well as technical aspects of MRI and statistical analysis. Methods: Protocol was pre-registered on NIHR PROSPERO database. MEDLINE, Web of Science and EMBASE databases were searched from 1946 to 15th August 2020 for all studies investigating either diabetic or HIV neuropathy and MRI, focusing exclusively on studies investigating symmetrical polyneuropathy. The NIH quality assessment tool for observational and cross-sectional cohort studies was used for risk of bias assessment. Results: The search resulted in 18 papers eligible for review, 18 for diabetic neuropathy and 0 for HIV neuropathy. Risk of bias assessment demonstrated that studies generally lacked explicit sample size justifications, and some may be underpowered. Whilst most studies made efforts to balance groups for confounding variables (age, gender, BMI, disease duration), there was lack of consistency between studies. Overall, the literature provides convincing evidence that DPN is associated with larger nerve cross sectional area, T2-weighted hyperintense and hypointense lesions, evidence of nerve oedema on Dixon imaging, decreased fractional anisotropy and increased apparent diffusion coefficient compared with controls. Analysis to date is largely restricted to the sciatic nerve or its branches. Conclusions: There is emerging evidence that various structural MR metrics may be useful as biomarkers in diabetic polyneuropathy, and areas for future direction are discussed. Expanding this technique to other forms of peripheral neuropathy, including HIV neuropathy, would be of value. Systematic Review Registration: (identifier: CRD 42020167322) https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=167322.
Collapse
Affiliation(s)
- Matthew C. Evans
- Pain Research, Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, London, United Kingdom
- Department of Brain Sciences, Care Research and Technology Centre, UK Dementia Research Institute, London, United Kingdom
| | - Charles Wade
- Department of Brain Sciences, Care Research and Technology Centre, UK Dementia Research Institute, London, United Kingdom
| | - David Hohenschurz-Schmidt
- Pain Research, Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Pete Lally
- Department of Brain Sciences, Care Research and Technology Centre, UK Dementia Research Institute, London, United Kingdom
- Royal School of Mines, Imperial College London, London, United Kingdom
| | - Albert Ugwudike
- Royal School of Mines, Imperial College London, London, United Kingdom
| | - Kamal Shah
- Royal School of Mines, Imperial College London, London, United Kingdom
| | - Neal Bangerter
- Royal School of Mines, Imperial College London, London, United Kingdom
| | - David J. Sharp
- Department of Brain Sciences, Care Research and Technology Centre, UK Dementia Research Institute, London, United Kingdom
| | - Andrew S. C. Rice
- Pain Research, Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, London, United Kingdom
| |
Collapse
|
7
|
Manoharan D, Sudhakaran D, Goyal A, Srivastava DN, Ansari MT. Clinico-radiological review of peripheral entrapment neuropathies - Part 1 upper limb. Eur J Radiol 2020; 131:109234. [PMID: 32949858 DOI: 10.1016/j.ejrad.2020.109234] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 06/21/2020] [Accepted: 08/08/2020] [Indexed: 02/06/2023]
Abstract
PURPOSE This article aims to review the pertinent anatomy, etiopathogenesis, current clinical and radiological concepts and principles of management in case of upper limb entrapment neuropathies. METHODS The review is based on critical analysis of the existing literature as well as our experience in dealing with entrapment neuropathies. RESULTS Entrapment neuropathies of the upper limb peripheral nerves are common conditions that are often misdiagnosed because of their varying clinical presentations and lack of standardized diagnostic methods. Clinical assessment and electrodiagnostic studies have been the mainstay; however, imaging techniques have provided newer insights into the pathophysiology of these entities, leading to a paradigm shift in their diagnosis and management. The current best practice protocols for entrapment syndromes are constantly evolving with increasing emphasis on the role high-resolution ultrasound and magnetic resonance imaging. Many imaging criteria are described and we have tried to present the most validated measurements for diagnosing entrapment neuropathies. CONCLUSION It is imperative for a clinical radiologist to be familiar with the etiopathogenesis and clinical features of these conditions, in addition to being thorough with the anatomy and the latest imaging strategies.
Collapse
Affiliation(s)
- Dinesh Manoharan
- Department of Radiology, All India Institute of Medical Sciences, New Delhi, India
| | - Dipin Sudhakaran
- Department of Radiology, All India Institute of Medical Sciences, New Delhi, India
| | - Ankur Goyal
- Department of Radiology, All India Institute of Medical Sciences, New Delhi, India.
| | | | - Mohd Tahir Ansari
- Department of Orthopedics, All India Institute of Medical Sciences, New Delhi, India
| |
Collapse
|
8
|
Abstract
Magnetic resonance imaging (MRI) has been used extensively in revealing pathological changes in the central nervous system. However, to date, MRI is very much underutilized in evaluating the peripheral nervous system (PNS). This underutilization is generally due to two perceived weaknesses in MRI: first, the need for very high resolution to image the small structures within the peripheral nerves to visualize morphological changes; second, the lack of normative data in MRI of the PNS and this makes reliable interpretation of the data difficult. This article reviews current state-of-the-art capabilities in
in vivo MRI of human peripheral nerves. It aims to identify areas where progress has been made and those that still require further improvement. In particular, with many new therapies on the horizon, this review addresses how MRI can be used to provide non-invasive and objective biomarkers in the evaluation of peripheral neuropathies. Although a number of techniques are available in diagnosing and tracking pathologies in the PNS, those techniques typically target the distal peripheral nerves, and distal nerves may be completely degenerated during the patient’s first clinic visit. These techniques may also not be able to access the proximal nerves deeply embedded in the tissue. Peripheral nerve MRI would be an alternative to circumvent these problems. In order to address the pressing clinical needs, this review closes with a clinical protocol at 3T that will allow high-resolution, high-contrast, quantitative MRI of the proximal peripheral nerves.
Collapse
Affiliation(s)
- Yongsheng Chen
- Department of Neurology, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - E Mark Haacke
- Department of Radiology, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - Jun Li
- Department of Neurology, Wayne State University School of Medicine, Detroit, MI, 48201, USA.,Center for Molecular Medicine & Genetics, Wayne State University School of Medicine, Detroit, MI, 48201, USA.,Department of Biochemistry, Microbiology and Immunology, Wayne State University School of Medicine, Detroit, MI, 48201, USA.,John D. Dingell VA Medical Center, Detroit, MI, 48201, USA
| |
Collapse
|
9
|
Abstract
Radiofrequency (RF) coils are an essential part of the magnetic resonance (MR) system. To exploit the inherently higher signal-to-noise ratio at ultrahigh magnetic fields (UHF), research sites were forced to build up expertise in RF coil development, as the number of commercially available RF coils were limited. In addition, an integrated transmit body RF coil, which is well-established at MR systems of lower field strength, is still missing at UHF due to technical and physical constraints. This review article provides a brief recapitulation of RF characteristics and RF coils in general to introduce terminology and RF-related parameters, and will then provide an extensive overview of current state-of-the-art RF coils used for MRI from head to toe at 7 Tesla. Finally, a section on RF safety will briefly discuss challenges in performing a safety assessment for custom-designed RF coils, and issues arising from the interaction of the RF field and potentially implanted medical devices.
Collapse
Affiliation(s)
- Oliver Kraff
- Erwin L. Hahn Institute for MR Imaging, University of Duisburg-Essen, Essen, Germany
| | - Harald H Quick
- Erwin L. Hahn Institute for MR Imaging, University of Duisburg-Essen, Essen, Germany
- High-Field and Hybrid MR Imaging, University Hospital Essen, Essen, Germany
| |
Collapse
|