Diffusion-Weighted Magnetic Resonance Imaging Improves the Accuracy of Differentiation of Benign from Malignant Peripheral Nerve Sheath Tumors.

OBJECTIVE: In patients with neurofibromatosis type 1 (NF1), it is important to accurately determine when plexiform neurofibroma (pNF) transforms to a malignant peripheral nerve sheath tumor (MPNST). The purpose of this study is to investigate the usefulness of diffusion-weighted imaging (DWI) in differentiating pNF and MPNST in NF1 patients. METHODS: Among the NF1 patients who were referred to our hospital between 1985 and 2015, 10 cases of MPNST and 19 cases of pNF were included. We evaluated features of standard magnetic resonance imaging according to the differentiation criteria of malignancy from benignancy as previously reported, apparent diffusion coefficient (ADC) value based on the DWI and the correlation between ADC value and benignancy/malignancy. ROC analysis was performed to determine the appropriate cutoff value of ADC. RESULTS: There were significant differences between MPNST and pNF in the size of the tumor (P = 0.009), peripheral enhancement pattern (P = 0.002), perilesional edema-like zone (P = 0.0008), and intratumoral cystic change (P = 0.02). The mean and minimum values of ADC were significantly lower in MPNST than those in pNF (P = 0.03 and P = 0.003, respectively). When we set a cutoff value of mean ADC as 1.85 × 10-3 mm2/s, the sensitivity and specificity were 80% and 74%, respectively. The area under the curve value improved by adding the Wasa score to the mean ADC evaluation. CONCLUSIONS: ADC values determined by DWI are useful in differentiating MPNST from pNF and adding ADC evaluation to standard MRI evaluation improved the diagnostic accuracy.

Peripheral nerve adaptations to 10 days of horizontal bed rest in healthy young adult males.

Space analogs, such as bed rest, are used to reproduce microgravity-induced morphological and physiological changes and can be used as clinical models of prolonged inactivity. Nevertheless, nonuniform decreases in muscle mass and function have been frequently reported, and peripheral nerve adaptations have been poorly studied, although some of these mechanisms may be explained. Ten young healthy males (18-33 yr) underwent 10 days of horizontal bed rest. Peripheral neurophysiological assessments were performed bilaterally for the dominant (DL) and nondominant upper and lower limbs (N-DL) on the 1st and 10th day of bed rest, including ultrasound of the median, deep peroneal nerve (DPN), and common fibular nerve (CFN) , as well as a complete nerve conduction study (NCS) of the upper and lower limbs. Consistently, reduced F waves, suggesting peripheral nerve dysfunction, of both the peroneal (DL: P = 0.005, N-DL: P = 0.013) and tibial nerves (DL: P = 0.037, N-DL: P = 0.005) were found bilaterally, whereas no changes were observed in nerve ultrasound or other parameters of the NCS of both the upper and lower limbs. In these young healthy males, only the F waves, known to respond to postural changes, were significantly affected by short-term bed rest. These preliminary results suggest that during simulated microgravity, most changes occur at the muscle or central nervous system level. Since the assessment of F waves is common in clinical neurophysiological examinations, caution should be used when testing individuals after prolonged immobility.

Dermal and cardiac autonomic fiber involvement in Parkinson's disease and multiple system atrophy.

Pathological aggregates of alpha-synuclein in peripheral dermal nerve fibers can be detected in patients with idiopathic Parkinson's disease and multiple system atrophy. This study combines skin biopsy staining for p-alpha-synuclein depositions and radionuclide imaging of the heart with [123I]-metaiodobenzylguanidine to explore peripheral denervation in both diseases. To this purpose, 42 patients with a clinical diagnosis of Parkinson's disease or multiple system atrophy were enrolled. All patients underwent a standardized clinical work-up including neurological evaluation, neurography, and blood samples. Skin biopsies were obtained from the distal and proximal leg, back, and neck for immunofluorescence double labeling with anti-p-alpha-synuclein and anti-PGP9.5. All patients underwent myocardial [123I]-metaiodobenzylguanidine scintigraphy. Dermal p-alpha-synuclein was observed in 47.6% of Parkinson's disease patients and was mainly found in autonomic structures. 81.0% of multiple system atrophy patients had deposits with most of cases in somatosensory fibers. The [123I]-metaiodobenzylguanidine heart-to-mediastinum ratio was lower in Parkinson's disease than in multiple system atrophy patients (1.94 ± 0.63 vs. 2.91 ± 0.96; p < 0.0001). Irrespective of the diagnosis, uptake was lower in patients with than without p-alpha-synuclein in autonomic structures (1.42 ± 0.51 vs. 2.74 ± 0.83; p < 0.0001). Rare cases of Parkinson's disease with p-alpha-synuclein in somatosensory fibers and multiple system atrophy patients with deposits in autonomic structures or both fiber types presented with clinically overlapping features. In conclusion, this study suggests that alpha-synuclein contributes to peripheral neurodegeneration and mediates the impairment of cardiac sympathetic neurons in patients with synucleinopathies. Furthermore, it indicates that Parkinson's disease and multiple system atrophy share pathophysiologic mechanisms of peripheral nervous system dysfunction with a clinical overlap.

Changes in motor nerve excitability in acute phase Guillain-Barré syndrome.

BACKGROUND: The most common subtypes of Guillain-Barré syndrome (GBS) are acute inflammatory demyelinating polyneuropathy (AIDP) and acute motor axonal neuropathy (AMAN). In the first days after the onset of weakness, standard nerve conduction studies (NCS) may not distinguish GBS subtypes. Reduced nerve excitability may be an early symptom of nerve dysfunction, which can be determined with the compound muscle action potential (CMAP) scan. The aim of this study was to explore whether early changes in motor nerve excitability in GBS patients are related to various subtypes. METHODS: Prospective case-control study in 19 GBS patients from The Netherlands and 22 from Bangladesh. CMAP scans were performed within 2 days of hospital admission and NCS 7-14 days after onset of weakness. CMAP scans were also performed in age- and country-matched controls. RESULTS: CMAP scan patterns of patients who were classified as AMAN were distinctly different compared to the CMAP scan patterns of the patients who were classified as AIDP. The most pronounced differences were found in the stimulus intensity parameters. CONCLUSIONS: CMAP scans made at hospital admission demonstrate several characteristics that can be used as an early indicator of GBS subtype.

Mapping the rest of the human connectome: Atlasing the spinal cord and peripheral nervous system.

The emergence of diffusion, structural, and functional neuroimaging methods has enabled major multi-site efforts to map the human connectome, which has heretofore been defined as containing all neural connections in the central nervous system (CNS). However, these efforts are not structured to examine the richness and complexity of the peripheral nervous system (PNS), which arguably forms the (neglected) rest of the connectome. Despite increasing interest in an atlas of the spinal cord (SC) and PNS which is simultaneously stereotactic, interactive, electronically dissectible, scalable, population-based and deformable, little attention has thus far been devoted to this task of critical importance. Nevertheless, the atlasing of these complete neural structures is essential for neurosurgical planning, neurological localization, and for mapping those components of the human connectome located outside of the CNS. Here we recommend a modification to the definition of the human connectome to include the SC and PNS, and argue for the creation of an inclusive atlas to complement current efforts to map the brain's human connectome, to enhance clinical education, and to assist progress in neuroscience research. In addition to providing a critical overview of existing neuroimaging techniques, image processing methodologies and algorithmic advances which can be combined for the creation of a full connectome atlas, we outline a blueprint for ultimately mapping the entire human nervous system and, thereby, for filling a critical gap in our scientific knowledge of neural connectivity.

Improved visualization of diffusion-prepared MR neurography (SHINKEI) in the lumbosacral plexus combining high-intensity reduction (HIRE) technique.

PURPOSE: This study attempted to improve visualization of the pelvic nervous system using the high-intensity reduction (HIRE)-nerve-SHeath signal increased with INKed rest-tissue RARE Imaging (SHINKEI) technique that involves subtracting signals of 3D heavily T2W images from SHINKEI images. We identified the optimum TE value for 3D heavily T2W images and assessed the usefulness of the HIRE-SHINKEI technique. MATERIALS AND METHODS: Coronal lumbosacral plexus images were acquired from six healthy volunteers at 3 T. We optimized the TE of the 3D heavily T2-weighted (T2W) images in HIRE-SHINKEI and compared HIRE-SHINKEI images with conventional SHINKEI images with respect to nerve depiction, and vein, bladder, and cerebrospinal fluid (CSF) signal suppression using a 5-point scale. RESULTS: In 3D heavily T2W images optimized by HIRE-SHINKEI technique, the signal corresponding to nerves became significantly lower at TE = 400 ms (p < 0.0005), while that of veins occurred at TE = 400 ms and 600 ms (p < 0.05). The suppression of bladder signals was significant at TE = 400, 600, and 800 ms (p < 0.05); however, there was no difference in signal inhibition from CSF at all TEs tested. Based on these results, an optimal TE of 600 ms was identified for 3D heavily T2W images; these images corresponded to the minimal loss of nerve signal and simultaneous maximum subtraction of signals from the bladder, vein, and CSF with dissimilar T2 values. Compared with SHINKEI images, the optimized HIRE-SHINKEI images selectively delineated nerves in greater detail, and along with significant signal suppression of the bladder (p < 0.0001) and veins (p < 0.05). CONCLUSION: HIRE-SHINKEI can be used to better visualize the lumbosacral plexus with higher signal suppression of other pelvic structures. Such detailed Magnetic resonance neurography and selective depiction of nerves are useful for the diagnosis of peripheral nerve disorders.

Peripheral nerve stimulation limits of a high amplitude and slew rate magnetic field gradient coil for neuroimaging.

PURPOSE: To establish peripheral nerve stimulation (PNS) thresholds for an ultra-high performance magnetic field gradient subsystem (simultaneous 200-mT/m gradient amplitude and 500-T/m/s gradient slew rate; 1 MVA per axis [MAGNUS]) designed for neuroimaging with asymmetric transverse gradients and 42-cm inner diameter, and to determine PNS threshold dependencies on gender, age, patient positioning within the gradient subsystem, and anatomical landmarks. METHODS: The MAGNUS head gradient was installed in a whole-body 3T scanner with a custom 16-rung bird-cage transmit/receive RF coil compatible with phased-array receiver brain coils. Twenty adult subjects (10 male, mean ± SD age = 40.4 ± 11.1 years) underwent the imaging and PNS study. The tests were repeated by displacing subject positions by 2-4 cm in the superior-inferior and anterior-posterior directions. RESULTS: The x-axis (left-right) yielded mostly facial stimulation, with mean ΔGmin = 111 ± 6 mT/m, chronaxie = 766 ± 76 µsec. The z-axis (superior-inferior) yielded mostly chest/shoulder stimulation (123 ± 7 mT/m, 620 ± 62 µsec). Y-axis (anterior-posterior) stimulation was negligible. X-axis and z-axis thresholds tended to increase with age, and there was negligible dependency with gender. Translation in the inferior and posterior directions tended to increase the x-axis and z-axis thresholds, respectively. Electric field simulations showed good agreement with the PNS results. Imaging at MAGNUS gradient performance with increased PNS threshold provided a 35% reduction in noise-to-diffusion contrast as compared with whole-body performance (80 mT/m gradient amplitude, 200 T/m/sec gradient slew rate). CONCLUSION: The PNS threshold of MAGNUS is significantly higher than that for whole-body gradients, which allows for diffusion gradients with short rise times (under 1 msec), important for interrogating brain microstructure length scales.

Peripheral nervous system alterations in infant and adult neurofibromatosis type 2.

OBJECTIVE: To examine the involvement of dorsal root ganglia and peripheral nerves in children with neurofibromatosis type 2 compared to healthy controls and symptomatic adults by in vivo high-resolution magnetic resonance neurography. METHODS: In this prospective multicenter study, the lumbosacral dorsal root ganglia and sciatic, tibial, and peroneal nerves were examined in 9 polyneuropathy-negative children diagnosed with neurofibromatosis type 2 by a standardized magnetic resonance neurography protocol at 3T. Volumes of dorsal root ganglia L3 to S2 and peripheral nerve lesions were assessed and compared to those of 29 healthy children. Moreover, dorsal root ganglia volumes and peripheral nerve lesions were compared to those of 14 adults with neurofibromatosis type 2. RESULTS: Compared to healthy controls, dorsal root ganglia hypertrophy was a consistent finding in children with neurofibromatosis type 2 (L3 +255%, L4 +289%, L5 +250%, S1 +257%, and S2 +218%, p < 0.001) with an excellent diagnostic accuracy. Moreover, peripheral nerve lesions occurred with a high frequency in those children compared to healthy controls (18.89 ± 11.11 vs 0.90 ± 1.08, p < 0.001). Children and adults with neurofibromatosis type 2 showed nonsignificant differences in relative dorsal root ganglia hypertrophy rates (p = 0.85) and peripheral nerve lesions (p = 0.28). CONCLUSIONS: Alterations of peripheral nerve segments occur early in the course of neurofibromatosis type 2 and are evident even in children not clinically affected by peripheral polyneuropathy. While those early alterations show similar characteristics compared to adults with neurofibromatosis type 2, the findings of this study suggest that secondary processes might be responsible for the development and severity of associated polyneuropathy.

Recent Advances in Pediatric Brain, Spine, and Neuromuscular Magnetic Resonance Imaging Techniques.

Magnetic resonance imaging (MRI) is a powerful radiologic tool with the ability to generate a variety of proton-based signal contrast from tissues. Owing to this immense flexibility in signal generation, new MRI techniques are constantly being developed, tested, and optimized for clinical utility. In addition, the safe and nonionizing nature of MRI makes it a suitable modality for imaging in children. In this review article, we summarize a few of the most popular advances in MRI techniques in recent years. In particular, we highlight how these new developments have affected brain, spine, and neuromuscular imaging and focus on their applications in pediatric patients. In the first part of the review, we discuss new approaches such as multiphase and multidelay arterial spin labeling for quantitative perfusion and angiography of the brain, amide proton transfer MRI of the brain, MRI of brachial plexus and lumbar plexus nerves (i.e., neurography), and T2 mapping and fat characterization in neuromuscular diseases. In the second part of the review, we focus on describing new data acquisition strategies in accelerated MRI aimed collectively at reducing the scan time, including simultaneous multislice imaging, compressed sensing, synthetic MRI, and magnetic resonance fingerprinting. In discussing the aforementioned, the review also summarizes the advantages and disadvantages of each method and their current state of commercial availability from MRI vendors.

Toward in vivo determination of peripheral nervous system immune activity in amyotrophic lateral sclerosis.

INTRODUCTION: We sought to identify patients with amyotrophic lateral sclerosis (ALS) who displayed suspected peripheral nervous system (PNS) inflammation to compare them to those with suspected PNS degeneration. METHODS: We measured sonographic median and ulnar nerve cross-sectional area (CSA) and cerebrospinal fluid albumin/serum albumin ratio (Qalb ) in patients with ALS to classify them as having suspected PNS degeneration (small CSA/low Qalb ) or inflammation (larger CSA/high Qalb ). RESULTS: Fifty-seven percent of patients had suspected PNS degeneration, 21% had suspected PNS inflammation, and 21% displayed suspected "normal PNS state." Suspected PNS degeneration was related to classic ALS, shorter disease duration, and a smaller hypoechoic nerve area. Suspected PNS inflammation was associated with men, longer disease duration, and a larger hypoechoic nerve area and was the dominant finding in superoxide dismutase 1 mutation carriers. DISCUSSION: Our simple approach might aid in the in vivo differentiation of supposed ALS subtypes, those with suspected PNS degeneration vs. inflammation, for stratification in clinical trials. Muscle Nerve 59:567-567, 2019.

Prediction of peripheral nerve stimulation thresholds of MRI gradient coils using coupled electromagnetic and neurodynamic simulations.

PURPOSE: As gradient performance increases, peripheral nerve stimulation (PNS) is becoming a significant constraint for fast MRI. Despite its impact, PNS is not directly included in the coil design process. Instead, the PNS characteristics of a gradient are assessed on healthy subjects after prototype construction. We attempt to develop a tool to inform coil design by predicting the PNS thresholds and activation locations in the human body using electromagnetic field simulations coupled to a neurodynamic model. We validate the approach by comparing simulated and experimentally determined thresholds for 3 gradient coils. METHODS: We first compute the electric field induced by the switching fields within a detailed electromagnetic body model, which includes a detailed atlas of peripheral nerves. We then calculate potential changes along the nerves and evaluate their response using a neurodynamic model. Both a male and female body model are used to study 2 body gradients and 1 head gradient. RESULTS: There was good agreement between the average simulated thresholds of the male and female models with the experimental average (normalized root-mean-square error: <10% and <5% in most cases). The simulation could also interrogate thresholds above those accessible by the experimental setup and allowed identification of the site of stimulation. CONCLUSIONS: Our simulation framework allows accurate prediction of gradient coil PNS thresholds and provides detailed information on location and "next nerve" thresholds that are not available experimentally. As such, we hope that PNS simulations can have a potential role in the design phase of high performance MRI gradient coils.

Electrode fabrication and interface optimization for imaging of evoked peripheral nervous system activity with electrical impedance tomography (EIT).

OBJECTIVE: Non-invasive imaging techniques are undoubtedly the ideal methods for continuous monitoring of neural activity. One such method, fast neural electrical impedance tomography (EIT) has been developed over the past decade in order to image neural action potentials with non-penetrating electrode arrays. APPROACH: The goal of this study is two-fold. First, we present a detailed fabrication method for silicone-based multiple electrode arrays which can be used for epicortical or neural cuff applications. Secondly, we optimize electrode material coatings in order to achieve the best accuracy in EIT reconstructions. MAIN RESULTS: The testing of nanostructured electrode interface materials consisting of platinum, iridium oxide, and PEDOT:pTS in saline tank experiments demonstrated that the PEDOT:pTS coating used in this study leads to more accurate reconstruction dimensions along with reduced phase separation between recording channels. The PEDOT:pTS electrodes were then used in vivo to successfully image and localize the evoked activity of the recurrent laryngeal fascicle from within the cervical vagus nerve. SIGNIFICANCE: These results alongside the simple fabrication method presented here position EIT as an effective method to image neural activity.

Perineural Invasion and Perineural Tumor Spread in Head and Neck Cancer.

Perineural invasion (PNI), the neoplastic invasion of nerves, is a common pathologic finding in head and neck cancer that is associated with poor clinical outcomes. PNI is a histologic finding of tumor cell infiltration and is distinct from perineural tumor spread (PNTS), which is macroscopic tumor involvement along a nerve extending from the primary tumor that is by definition more advanced, being radiologically or clinically apparent. Despite widespread acknowledgment of the prognostic significance of PNI and PNTS, the mechanisms underlying its pathogenesis remain largely unknown, and specific therapies targeting nerve invasion are lacking. The use of radiation therapy for PNI and PNTS can improve local control and reduce devastating failures at the skull base. However, the optimal volumes to be delineated with respect to targeting cranial nerve pathways are not well defined, and radiation can carry risks of major toxicity secondary to the location of adjacent critical structures. Here we examine the pathogenesis of these phenomena, analyze the role of radiation in PNI and PNTS, and propose guidelines for radiation treatment design based on the best available evidence and the authors' collective experience to advance understanding and therapy of this ominous cancer phenotype.

Evaluation of local look diffusion tensor imaging for magnetic resonance tractography of the periprostatic neurovascular bundle.

The purpose of this study was to compare diffusion tensor imaging using the local look technique and sensitivity encoding for tractography of the periprostatic neurovascular bundle. We compared the surrounding tissues of the prostate in eight healthy volunteers. The results of tractography in terms of the numbers of fibers and the fractional anisotropy map were evaluated. Distortion was evaluated using the dice similarity coefficient between isotropic diffusion images created from diffusion tensor images and T2-weighted images. The number of lines in tractography was significantly greater in diffusion tensor imaging using the local look technique (p < 0.001). Although there was no difference in image distortion of the prostate between methods, an artifact appeared in the center of the diffusion tensor image using sensitivity encoding. In conclusion, diffusion tensor imaging using the local look technique was superior to that using sensitivity encoding for tractography of the periprostatic neurovascular bundle.

Flaccid paralysis in neuromyelitis optica: An atypical presentation with possible involvement of the peripheral nervous system.

BACKGROUND: Neuromyelitis optica spectrum disorders (NMOSD) typically lead to spastic paraparesis and spare the peripheral nervous system (PNS). CASE REPORT: Here, we describe an anti-aquaporin-4-seropositive NMOSD patient suffering from acute transverse myelitis with painful, flaccid paralysis and incontinence of urine and feces. Due to the involvement of the PNS as indicated by electrodiagnostic examination, we verified the expression of aquaporin-4-channels on the proximal dorsal spinal radix of rats by staining rat tissue with human NMOSD serum. CONCLUSION: This case suggests a manifestation of the proximal PNS in NMOSD. Thus, NMOSD should be considered as a differential diagnosis for patients presenting with signs of spinal cord disease and additional radicular involvement.

Desplazamiento del sistema nervioso a partir del movimiento articular mediante ecografía. Revisión bibliográfica / Displacement of the nervous system through articular movement by ultrasound. Bibliographic review

El sistema nervioso tiene la capacidad de adaptarse a las fuerzas mecánicas de tensión, compresión y cizallamiento a las que se ve expuesto en los movimientos diarios. La reducción del deslizamiento del nervio puede alterar su función por el incremento de la tensión neural, pudiendo afectar negativamente y contribuir a la aparición de dolor. El objetivo del estudio es revisar la bibliografía actual respecto al desplazamiento del sistema nervioso y cómo medirlo. Para ello se realiza una búsqueda en Pubmed y PEDro de artículos donde se mida el desplazamiento neural mediante la técnica de «frame-by-frame cross correlation system». Se seleccionan 20 estudios: 14 de ellos miden el desplazamiento en personas sanas y 6 comparan con algún tipo de neuropatía periférica. Los resultados muestran la capacidad de movimiento del sistema nervioso periférico durante los diferentes movimientos de segmentos corporales para adaptarse al espacio por donde discurre, aunque no hay una diferencia significativa de desplazamiento entre personas sanas y pacientes con afectación nerviosa

The nervous system has the capacity to adapt to the mechanical forces of tension, compression and shearing to which it is exposed in daily movements. Reduction of nerve slide may alter its function by increasing neural tension, which may have an adverse effect, contributing to the onset of pain. The objective of the study was to review the current literature regarding the movement of the nervous system and how to measure it. To do this, a search was undertaken in Pubmed and PEDro of articles where neural displacement is measured by the «frame-by-frame cross correlation system» technique. Twenty studies were selected: 14 measured displacement in healthy subjects, and 6 compared some form of peripheral neuropathy. The results show that the peripheral nervous system is displaced during the different movements of body segments to adapt to the space through which it runs, although there is no significant difference in displacement between healthy people and patients with nerve involvement

Central and peripheral nervous system immune-mediated demyelinating disease after allogeneic hematopoietic stem cell transplantation.

OBJECTIVE: We aimed to evaluate clinical and diagnostic features of central and peripheral immune-mediated demyelinating disease (CPID) in allogeneic hematopoietic stem cell transplantation (aHSCT) recipients. BACKGROUND: CPID refers to the late-onset, immune-mediated neurological complications following aHSCT, when other frequent differential diagnoses have been ruled out, and when symptoms and signs of systemic GvHD manifestations are absent. METHODS: Case records at the University of Tuebingen, between 2001 and 2015, were screened to identify patients with CPID after aHSCT. RESULTS: Seven patients who developed CPID after aHSCT were identified. The average time interval from aHSCT until onset of CPID was 2.6 (±2.8) years (mean±SD). The most prevalent manifestations of CPID were optic neuritis and/or myelitis and polyneuropathy. Cerebrospinal fluid analyses involved elevated protein concentration and lymphocytic pleocytosis, while oligoclonal bands in CSF, but not in serum, were detected in 28% of cases. Aquaporin-4-antibodies were consistently absent. MRI studies showed features suggestive of demyelination processes, with cerebral and/or spinal cord white-matter involvement, and features compatible with cerebral vasculitis. Corticosteroids, Immunoglobulins, Cyclophosphamide, Rituximab and Interferon beta-1a showed marginal treatment responses, whereas plasma exchange resulted in marked clinical improvement in two treated patients. A chronic disease-course with persisting neurological deficits was prevalent. CONCLUSIONS: CPID may comprise a rare complication of aHSCT, which manifests as optic neuritis and/or myelitis and is accompanied by sensorimotor polyneuropathy. A concomitant systemic manifestation of GvHD is not mandatory for CPID diagnosis. Usually, CPID exhibits a chronic, persisting disease course. Thus, clinical awareness is required, as early diagnosis and aggressive treatment may be prognostically advantageous.

MR neurography for the evaluation of CIDP.

INTRODUCTION: To visualize peripheral nerves in patients with chronic inflammatory demyelinating polyneuropathy (CIDP), we used MR imaging. We also quantified the volumes of the brachial and lumbar plexus and their nerve roots. METHODS: Thirteen patients with CIDP and 12 healthy volunteers were enrolled. Whole-body MR neurography based on diffusion-weighted whole-body imaging with background body signal suppression (DWIBS) was performed. Peripheral nerve volumes were calculated from serial axial MR images. RESULTS: The peripheral nervous system was visualized with 3-dimensional reconstruction. Volumes ranged from 8.7 to 49.5 cm3 /m2 in the brachial plexus and nerve roots and from 10.2 to 53.5 cm3 /m2 in the lumbar plexus and nerve roots. Patients with CIDP had significantly larger volumes than controls (P < 0.05), and volume was positively correlated with disease duration. CONCLUSIONS: MR neurography and the measurement of peripheral nerve volume are useful for diagnosing and assessing CIDP. Muscle Nerve 55: 483-489, 2017.