Visualization of nerve fibers and their relationship to peripheral nerve tumors by diffusion tensor imaging

OBJECT The majority of growing and/or symptomatic peripheral nerve tumors are schwannomas and neurofibromas. They are almost always benign and can usually be resected while minimizing motor and sensory deficits if approached with the proper expertise and techniques. Intraoperative electrophysiological stimulation and recording techniques allow the surgeon to map the surface of the tumor in an effort to identify and thus avoid damaging functioning nerve fibers. Recently, MR diffusion tensor imaging (DTI) techniques have permitted the visualization of axons, because of their anisotropic properties, in peripheral nerves. The object of this study was to compare the distribution of nerve fibers as revealed by direct electrical stimulation with that seen on preoperative MR DTI. METHODS The authors conducted a retrospective chart review of patients with a peripheral nerve or nerve root tumor between March 2012 and January 2014. Diffusion tensor imaging and intraoperative data had been prospectively collected for patients with peripheral nerve tumors that were resected. Preoperative identification of the nerve fiber location in relation to the nerve tumor surface as seen on DTI studies was compared with the nerve fiber’s intraoperative localization using electrophysiological stimulation and recordings. RESULTS In 23 patients eligible for study there was good correlation between nerve fiber location on DTI and its anatomical location seen intraoperatively. Diffusion tensor imaging demonstrated the relationship of nerve fibers relative to the tumor with 95.7% sensitivity, 66.7% specificity, 75% positive predictive value, and 93.8% negative predictive value. CONCLUSIONS Preoperative DTI techniques are useful in helping the peripheral nerve surgeon to both determine the risks involved in resecting a nerve tumor and plan the safest surgical approach.

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4.7-T diffusion tensor imaging of acute traumatic peripheral nerve injury

Neurosurgical FOCUS ◽

10.3171/2015.6.focus1590 ◽

2015 ◽

Vol 39 (3) ◽

pp. E9 ◽

Cited By ~ 25

Author(s):

Richard B. Boyer ◽

Nathaniel D. Kelm ◽

D. Colton Riley ◽

Kevin W. Sexton ◽

Alonda C. Pollins ◽

...

Keyword(s):

Diffusion Tensor Imaging ◽

High Resolution ◽

Peripheral Nerve ◽

Nerve Injury ◽

Peripheral Nerve Injury ◽

Diffusion Tensor ◽

Ex Vivo ◽

Nerve Fibers ◽

Nerve Transection ◽

Nerve Injuries

Diagnosis and management of peripheral nerve injury is complicated by the inability to assess microstructural features of injured nerve fibers via clinical examination and electrophysiology. Diffusion tensor imaging (DTI) has been shown to accurately detect nerve injury and regeneration in crush models of peripheral nerve injury, but no prior studies have been conducted on nerve transection, a surgical emergency that can lead to permanent weakness or paralysis. Acute sciatic nerve injuries were performed microsurgically to produce multiple grades of nerve transection in rats that were harvested 1 hour after surgery. High-resolution diffusion tensor images from ex vivo sciatic nerves were obtained using diffusion-weighted spin-echo acquisitions at 4.7 T. Fractional anisotropy was significantly reduced at the injury sites of transected rats compared with sham rats. Additionally, minor eigenvalues and radial diffusivity were profoundly elevated at all injury sites and were negatively correlated to the degree of injury. Diffusion tensor tractography showed discontinuities at all injury sites and significantly reduced continuous tract counts. These findings demonstrate that high-resolution DTI is a promising tool for acute diagnosis and grading of traumatic peripheral nerve injuries.

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Diffusion tensor imaging to visualize axons in the setting of nerve injury and recovery

Neurosurgical FOCUS ◽

10.3171/2015.6.focus15211 ◽

2015 ◽

Vol 39 (3) ◽

pp. E10 ◽

Cited By ~ 17

Author(s):

Thomas Anthony Gallagher ◽

Neil G. Simon ◽

Michel Kliot

Keyword(s):

Diffusion Tensor Imaging ◽

Peripheral Nerve ◽

Nerve Injury ◽

Peripheral Nerves ◽

Diffusion Tensor ◽

Nerve Fibers ◽

Accurate Localization ◽

Peripheral Nerve Trauma ◽

Nerve Trauma ◽

Diffusion Tensor Imaging Dti

Successful management of peripheral nerve trauma relies on accurate localization of the injury and grading of the severity of nerve injury to determine whether surgical intervention is required. Existing techniques, such as electrodiagnostic studies and conventional imaging modalities, provide important information, but are limited by being unable to distinguish severe nerve lesions in continuity that will recover from those that will not. Diffusion tensor imaging (DTI) and tractography of peripheral nerves provide a novel technique to localize and grade nerve injury, by assessing the integrity of the nerve fibers across the site of nerve injury. Diffusion tensor imaging and tractography also hold promise as markers of early nerve regeneration, prior to clinical and electrodiagnostic evidence of recovery. In the present review, the techniques of peripheral nerve DTI and tractography are discussed with respect to peripheral nerve trauma, with illustrative cases demonstrating potential roles of these novel approaches.

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Diffusion tensor imaging–based fiber tracking for prediction of the position of the facial nerve in relation to large vestibular schwannomas

Journal of Neurosurgery ◽

10.3171/2011.7.jns11495 ◽

2011 ◽

Vol 115 (6) ◽

pp. 1087-1093 ◽

Cited By ~ 52

Author(s):

Venelin M. Gerganov ◽

Mario Giordano ◽

Madjid Samii ◽

Amir Samii

Keyword(s):

Diffusion Tensor Imaging ◽

Facial Nerve ◽

Diffusion Tensor ◽

Fiber Tracking ◽

Anatomical Location ◽

Visualization Technique ◽

Correlative Analysis ◽

Nerve Tumor ◽

Anatomical Images

Object The reliable preoperative visualization of facial nerve location in relation to vestibular schwannoma (VS) would allow surgeons to plan tumor removal accordingly and may increase the safety of surgery. In this prospective study, the authors attempted to validate the reliability of facial nerve diffusion tensor (DT) imaging–based fiber tracking in a series of patients with large VSs. Furthermore, the authors evaluated the potential of this visualization technique to predict the morphological shape of the facial nerve (tumor compression–related flattening of the nerve). Methods Diffusion tensor imaging and anatomical images (constructive interference in steady state) were acquired in a series of 22 consecutive patients with large VSs and postprocessed with navigational software to obtain facial nerve fiber tracking. The location of the cerebellopontine angle (CPA) part of the nerve in relation to the tumor was recorded during surgery by the surgeon, who was blinded to the results of the fiber tracking. A correlative analysis was performed of the imaging-based location of the nerve compared with its in situ position in relation to the VS. Results Fibers corresponding to the anatomical location and course of the facial nerve from the brainstem to the internal auditory meatus were identified with the DT imaging–based fiber tracking technique in all 22 cases. The location of the CPA segment of the facial nerve in relation to the VS determined during surgery corresponded to the location of the fibers, predicted by the DT imaging–based fiber tracking, in 20 (90.9%) of the 22 patients. No DT imaging–based fiber tracking correlates were found with the 2 morphological types of the nerve (compact or flat). Conclusions The current study of patients with large VSs has shown that the position of the facial nerve in relation to the tumor can be predicted reliably (in 91%) using DT imaging–based fiber tracking. These are preliminary results that need further verification in a larger series.

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DTI and MTR Measures of Nerve Fiber Integrity in Pediatric Patients With Ankle Injury

Frontiers in Pediatrics ◽

10.3389/fped.2021.656843 ◽

2021 ◽

Vol 9 ◽

Author(s):

Scott A. Holmes ◽

Anastasia Karapanagou ◽

Steven J. Staffa ◽

David Zurakowski ◽

Ronald Borra ◽

...

Keyword(s):

Neuropathic Pain ◽

Peripheral Nerve ◽

Nerve Fiber ◽

Nerve Injury ◽

Diffusion Tensor ◽

Nerve Fibers ◽

Ankle Injury ◽

Future Research ◽

Post Injury ◽

Fibular Nerve

Acute peripheral nerve injury can lead to chronic neuropathic pain. Having a standardized, non-invasive method to evaluate pathological changes in a nerve following nerve injury would help with diagnostic and therapeutic assessments or interventions. The accurate evaluation of nerve fiber integrity after injury may provide insight into the extent of pathology and a patient's level of self-reported pain. The aim of this investigation was to evaluate the extent to which peripheral nerve integrity could be evaluated in an acute ankle injury cohort and how markers of nerve fiber integrity correlate with self-reported pain levels in afferent nerves. We recruited 39 pediatric participants with clinically defined neuropathic pain within 3 months of an ankle injury and 16 healthy controls. Participants underwent peripheral nerve MRI using diffusion tensor (DTI) and magnetization transfer imaging (MTI) of their injured and non-injured ankles. The imaging window was focused on the branching point of the sciatic nerve into the tibial and fibular division. Each participant completed the Pain Detection Questionnaire (PDQ). Findings demonstrated group differences in DTI and MTI in the sciatic, tibial and fibular nerve in the injured ankle relative to healthy control and contralateral non-injured nerve fibers. Only AD and RD from the injured fibular nerve correlated with PDQ scores which coincides with the inversion-dominant nature of this particular ankle injuruy cohort. Exploratory analyses highlight the potential remodeling stages of nerve injury from neuropathic pain. Future research should emphasize sub-acute time frames of injury to capture post-injury inflammation and nerve fiber recovery.

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Diffusion Is Directional: Innovative Diffusion Tensor Imaging to Improve Prostate Cancer Detection

Diagnostics ◽

10.3390/diagnostics11030563 ◽

2021 ◽

Vol 11 (3) ◽

pp. 563

Author(s):

Chen Shenhar ◽

Hadassa Degani ◽

Yaara Ber ◽

Jack Baniel ◽

Shlomit Tamir ◽

...

Keyword(s):

Prostate Cancer ◽

Diffusion Tensor Imaging ◽

Predictive Value ◽

Breast Imaging ◽

Normal Tissue ◽

Diffusion Tensor ◽

Peripheral Zone ◽

Predictive Values ◽

Directional Diffusion ◽

Central Gland

In the prostate, water diffusion is faster when moving parallel to duct and gland walls than when moving perpendicular to them, but these data are not currently utilized in multiparametric magnetic resonance imaging (mpMRI) for prostate cancer (PCa) detection. Diffusion tensor imaging (DTI) can quantify the directional diffusion of water in tissue and is applied in brain and breast imaging. Our aim was to determine whether DTI may improve PCa detection. We scanned patients undergoing mpMRI for suspected PCa with a DTI sequence. We calculated diffusion metrics from DTI and diffusion weighted imaging (DWI) for suspected lesions and normal-appearing prostate tissue, using specialized software for DTI analysis, and compared predictive values for PCa in targeted biopsies, performed when clinically indicated. DTI scans were performed on 78 patients, 42 underwent biopsy and 16 were diagnosed with PCa. The median age was 62 (IQR 54.4–68.4), and PSA 4.8 (IQR 1.3–10.7) ng/mL. DTI metrics distinguished PCa lesions from normal tissue. The prime diffusion coefficient (λ1) was lower in both peripheral-zone (p < 0.0001) and central-gland (p < 0.0001) cancers, compared to normal tissue. DTI had higher negative and positive predictive values than mpMRI to predict PCa (positive predictive value (PPV) 77.8% (58.6–97.0%), negative predictive value (NPV) 91.7% (80.6–100%) vs. PPV 46.7% (28.8–64.5%), NPV 83.3% (62.3–100%)). We conclude from this pilot study that DTI combined with T2-weighted imaging may have the potential to improve PCa detection without requiring contrast injection.

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Diffusion tensor imaging in children following prenatal myelomeningocele repair and its predictive value for the need and timing of subsequent CSF diversion surgery for hydrocephalus

Journal of Neurosurgery Pediatrics ◽

10.3171/2020.9.peds20570 ◽

2021 ◽

Vol 27 (4) ◽

pp. 391-399

Author(s):

Weihong Yuan ◽

Charles B. Stevenson ◽

Mekibib Altaye ◽

Blaise V. Jones ◽

James Leach ◽

...

Keyword(s):

Logistic Regression ◽

Regression Analysis ◽

Diffusion Tensor Imaging ◽

Logistic Regression Analysis ◽

Predictive Value ◽

Diffusion Tensor ◽

Linear Regression Analysis ◽

Model Performance ◽

Time Interval ◽

Csf Diversion

OBJECTIVE The aim of this study was to investigate diffusion tensor imaging (DTI), an objective and noninvasive neuroimaging technique, for its potential as an imaging biomarker to predict the need and timing of CSF diversion surgery in patients after prenatal myelomeningocele (MMC) repair. METHODS This was a retrospective analysis of data based on 35 pediatric patients after prenatal MMC repair (gestational age at birth 32.68 ± 3.42 weeks, range 24–38 weeks; 15 females and 20 males). A logistic regression analysis was used to classify patients to determine the need for CSF diversion surgery. The model performance was compared between using the frontooccipital horn ratio (FOHR) alone and using the FOHR combined with DTI values (the genu of the corpus callosum [gCC] and the posterior limb of the internal capsule [PLIC]). For patients who needed to be treated surgically, timing of the procedure was used as the clinical outcome to test the predictive value of DTI acquired prior to surgery based on a linear regression analysis. RESULTS Significantly lower fractional anisotropy (FA) values in the gCC (p = 0.014) and PLIC (p = 0.037) and higher mean diffusivity (MD) values in the gCC (p = 0.013) were found in patients who required CSF diversion surgery compared with those who did not require surgery (all p values adjusted for age). Based on the logistic regression analysis, the FOHR alone showed an accuracy of performance of 0.69 and area under the receiver operating characteristic curve (AUC) of 0.60. The performance of the model was higher when DTI measures were used in the logistic regression model (accuracy = 0.77, AUC = 0.84 for using DTI values in gCC; accuracy = 0.75, AUC = 0.84 for using DTI values in PLIC). Combining the DTI values of the gCC or PLIC and FOHR did not improve the model performance when compared with using the DTI values alone. In patients who needed CSF diversion surgery, significant correlation was found between DTI values in the gCC and the time interval between imaging and surgery (FA: ρ = 0.625, p = 0.022; MD: ρ = −0.6830, p = 0.010; both adjusted for age and FOHR). CONCLUSIONS The authors’ data demonstrated that DTI could potentially serve as an objective biomarker differentiating patients after prenatal MMC repair regarding those who may require surgery for MMC-associated hydrocephalus. The predictive value for the need and timing of CSF diversion surgery is highly clinically relevant for improving and optimizing decision-making for the treatment of hydrocephalus in this patient population.

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