Delayed Ferumoxtran-10-Enhanced Magnetic Resonance Neurography of the Lumbosacral Plexus: Impact on Vascular Suppression and Image Quality.

BACKGROUND: Intravenous Ferumoxtran-10 belongs to ultra-small superparamagnetic iron oxide particles and can be used for magnetic resonance neurography (MRN) as an alternative to other imaging methods which use contrast agents. PURPOSE: To examine the impact of intravenous Ferumoxtran-10 on vascular suppression and compare image quality to gadolinium (Gd)-enhanced image acquisition in MRN of lumbosacral plexus (LS). STUDY TYPE: Prospective. POPULATION/SUBJECTS: 17 patients with Ferumoxtran-10-enhanced MRN, and 20 patients with Gd-enhanced MRN. FIELDSTRENGTH/SEQUENCE: 3T/3D STIR sequence. ASSESSMENT: Image quality, nerve visibility and vascular suppression were evaluated by 3 readers using a 5-point Likert scale. STATISTICAL TESTS: Inter-reader agreement (IRA) was calculated using intraclass coefficients (ICC). Quantitative analysis of image quality was performed by signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) measurements and compared using Student's t-testing. RESULTS: Image quality, nerve visibility and vascular suppression were significantly higher for Ferumoxtran-10-enhanced MRN compared to Gd-enhanced MRN sequences (p < 0.05). IRA for image quality of nerves was good in Gd-enhanced and Ferumoxtran-10 MRN with ICC values of 0.76 and 0.89, respectively. IRA for nerve visibility was good in Gd- and Ferumoxtran-10 enhanced MR neurography (ICC 0.72 and 0.90). Mean SNR was significantly higher in Ferumoxtran-10-enhanced MRN for all analyzed structures, while mean CNR was for significantly better for S1 ganglion and femoral nerve in Ferumoxtran-10-enhanced MRN (p < 0.05). DATA CONCLUSION: Ferumoxtran-10-enhanced MRN of the LS plexus showed significantly higher image quality and nerve visibility with better vascular suppression as compared to Gd-enhanced MRN. EVIDENCE LEVEL: 2 TECHNICAL EFFICACY: Stage 3.

Magnetic Resonance Neurography of the Foot and Ankle.

Peripheral neuropathies of the foot and ankle can be challenging to diagnose clinically due to concomitant traumatic and nontraumatic or degenerative orthopedic conditions. Although clinical history, physical examination, and electrodiagnostic testing comprised of nerve conduction velocities and electromyography are used primarily for the identification and classification of peripheral nerve disorders, MR neurography (MRN) can be used to visualize the peripheral nerves as well as the skeletal muscles of the foot and ankle for primary neurogenic pathology and skeletal muscle denervation effect. Proper knowledge of the anatomy and pathophysiology of peripheral nerves is important for an MRN interpretation.

Magnetic resonance neurography in the diagnosis of neurological subtypes of thoracic outlet syndrome.

Neurological thoracic outlet syndrome (TOS) can be challenging to diagnose, particularly given its described subtypes of neurogenic TOS (NTOS) and disputed TOS (DTOS) that exhibit variable clinical presentations and etiologies. The diagnostic workup of TOS often includes magnetic resonance neurography (MRN) of the brachial plexus. Specific MRN imaging modifications for TOS evaluation are required to maximize spatial and contrast resolution to increase the conspicuity of nerve segments and their relationships to surrounding osseous structures. Dynamic assessment with arm positioning is used to evaluate outlet narrowing and compression of the plexus. Individual nerve segments are interrogated for their longitudinal and cross-sectional morphologies and signal characteristics. In patients with NTOS, MRN may reveal focal impingement of the C8/T1 nerve roots and/or lower trunk with accompanying abnormal T2-weighted signal hyperintensity. Predisposing anatomical entities include cervical ribs, rib synostoses, hypertrophic callous following clavicular fracture, remnant first thoracic rib from prior incomplete resection, and variable perineural scarring. In comparison, DTOS patients frequently demonstrate signal hyperintensity and enlargement of the mid plexus (trunk and division level), with narrowing of the costoclavicular interval. Following comprehensive diagnostic workup that frequently includes electrodiagnostic testing, patients are directed to different management pathways. Nonsurgical management is considered for all cases of DTOS; all patients with NTOS or DTOS who fail conservative treatment warrant referral for a surgical opinion. If surgery is pursued, MRN can be helpful in preoperative planning.

Contrast-enhanced magnetic resonance neurography for diagnosing brachial plexopathy: improved visualization and additional imaging features.

Contrast-enhanced magnetic resonance neurography (CE-MRN) holds promise for diagnosing brachial plexopathy by enhancing nerve visualization and revealing additional imaging features in various lesions. This study aims to validate CE-MRN's efficacy in improving brachial plexus (BP) imaging across different patient cohorts. Seventy-one subjects, including 19 volunteers and 52 patients with BP compression/entrapment, injury, and neoplasms, underwent both CE-MRN and plain MRN. Two radiologists assessed nerve visibility, with inter-reader agreement evaluated. Quantitative parameters such as signal intensity (SI), contrast-to-noise ratio (CNR), and contrast ratio (CR) of the C7 nerve were measured. Both qualitative scoring and quantitative metrics were compared between CE-MRN and plain MRN within each patient group. Patient classification followed the Neuropathy Score Reporting and Data System (NS-RADS), summarizing additional imaging features for each brachial plexopathy type. Inter-reader agreement for qualitative assessment was strong. CE-MRN significantly enhanced BP visualization and nerve-tissue contrast across all cohorts, particularly in volunteers and patients with injuries. It also uncovered additional imaging features such as hypointense signals in ganglia, compressed nerve sites, and neoplastic enhancements. CE-MRN effectively mitigated muscle edema and vascular contamination, enabling precise classification of BP injuries. Overall, CE-MRN consistently enhances BP visualization and provides valuable imaging features for accurate diagnosis.

Advances in Imaging of Compressive Neuropathies.

Ultrasound and magnetic resonance neurography are useful modalities to aid in the assessment of compressive neuropathies, although they are still limited in their resolution of nerve microstructure and their capacity to monitor postoperative nerve recovery. Optical coherence tomography, a preclinical imaging modality, is promising in its ability to better identify structural and potential physiologic changes to peripheral nerves, but requires additional testing and research prior to widespread clinical implementation. Further advances in nerve imaging may elucidate the ability to visualize the zone of nerve injury intraoperatively, monitor the progression of nerve regeneration, and localize problems during nerve recovery.

3D MR neurography with gadolinium contrast to improve the visualization of pelvic nerves and the branches.

Objective: To evaluate the effectiveness of 3D NerveVIEW sequence with gadolinium contrast on the visualization of pelvic nerves and their branches compared to that without contrast. Methods: Participants were scanned twice using 3D NerveVIEW sequence with and without gadolinium contrast to acquire pelvic nerve images. The signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and contrast ratio of the nerves were calculated and compared to determine the quality of images. To subjectively assess, using a 3-point scale, branch nerves critical to therapeutic decision-making, including the pelvic splanchnic nerve and pelvic plexus, the superior gluteal nerve, and the pudendal nerve. Results: In the 32 eligible participants after using contrast, the CNRs of the images of nerve-to-bone and nerve-to-vessel significantly increased (p < 0.05). The CR of the images with contrast of all nerve-to-surrounding tissues (i.e., bone, muscle, blood vessels, and fat) were also found significantly higher (p < 0.05). The assessment of observers also shows higher scores for images with contrast compared to images without contrast. Conclusion: The 3D NerveVIEW sequence combined with gadolinium contrast improved vascular suppression, increased the contrast between pelvic nerves and surrounding tissue, and enhanced the visualization of nerves and their branches. This study may be helpful for the technically challenging preoperative planning of pelvic diseases surgery.

Dorsal root ganglion magnetic resonance imaging biomarker correlations with pain in Fabry disease.

Fabry disease is a rare monogenetic, X-linked lysosomal storage disorder with neuropathic pain as one characteristic symptom. Impairment of the enzyme alpha-galactosidase A leads to an accumulation of globotriaosylceramide in the dorsal root ganglia. Here, we investigate novel dorsal root ganglia MR imaging biomarkers and their association with Fabry genotype and pain phenotype. In this prospective study, 89 Fabry patients were examined using a standardized 3 T MRI protocol of the dorsal root ganglia. Fabry pain was assessed through a validated Fabry pain questionnaire. The genotype was determined by diagnostic sequencing of the alpha-galactosidase A gene. MR imaging end-points were dorsal root ganglia volume by voxel-wise morphometric analysis and dorsal root ganglia T2 signal. Reference groups included 55 healthy subjects and Fabry patients of different genotype categories without Fabry pain. In patients with Fabry pain, T2 signal of the dorsal root ganglia was increased by +39.2% compared to healthy controls (P = 0.001) and by +29.4% compared to painless Fabry disease (P = 0.017). This effect was pronounced in hemizygous males (+40.7% compared to healthy; P = 0.008 and +29.1% compared to painless; P = 0.032) and was consistently observed across the genotype spectrum of nonsense (+38.1% compared to healthy, P < 0.001) and missense mutations (+39.2% compared to healthy; P = 0.009). T2 signal of dorsal root ganglia and globotriaosylsphingosine levels were the only independent predictors of Fabry pain (P = 0.047; P = 0.002). Volume of dorsal root ganglia was enlarged by +46.0% in Fabry males in the nonsense compared to missense genotype category (P = 0.005) and by +34.5% compared to healthy controls (P = 0.034). In painful Fabry disease, MRI T2 signal of dorsal root ganglia is increased across different genotypes. Dorsal root ganglion MRI T2 signal as a novel in vivo imaging biomarker may help to better understand whether Fabry pain is modulated or even caused by dorsal root ganglion pathology.

The role of imaging in focal neuropathies.

Electrodiagnostic testing (EDX) has been the diagnostic tool of choice in peripheral nerve disease for many years, but in recent years, peripheral nerve imaging has been used ever more frequently in daily clinical practice. Nerve ultrasound and magnetic resonance (MR) neurography are able to visualize nerve structures reliably. These techniques can aid in localizing nerve pathology and can reveal significant anatomical abnormalities underlying nerve pathology that may have been otherwise undetected by EDX. As such, nerve ultrasound and MR neurography can significantly improve diagnostic accuracy and can have a significant effect on treatment strategy. In this chapter, the basic principles and recent developments of these techniques will be discussed, as well as their potential application in several types of peripheral nerve disease, such as carpal tunnel syndrome (CTS), ulnar neuropathy at the elbow (UNE), radial neuropathy, brachial and lumbosacral plexopathy, neuralgic amyotrophy (NA), fibular, tibial, sciatic, femoral neuropathy, meralgia paresthetica, peripheral nerve trauma, tumors, and inflammatory neuropathies.

Improved visualization of median, ulnar nerves, and small branches in the wrist and palm using contrast-enhanced magnetic resonance neurography.

Background: Magnetic resonance imaging of peripheral nerves in the wrist and palm is challenging due to the small size, tortuous course, complex surrounding tissues, and accompanying blood vessels. The occurrence of carpal palmar lesions leads to edema, swelling, and mass effect, which may further interfere with the display and identification of nerves. Objective: To evaluate whether contrast-enhanced magnetic resonance neurography (ceMRN) improves the visualization of the morphology and pathology of the median, ulnar nerves, and their small branches in the wrist and palm. Design: An observational study. Methods: In total 57 subjects, including 36 volunteers and 21 patients with carpal palmar lesions, were enrolled and underwent ceMRN and non-contrast MRN (ncMRN) examination at 3.0 Tesla. The degree of vascular suppression, nerve visualization, diagnostic confidence, and lesion conspicuity was qualitatively assessed by two radiologists. Kappa statistics were obtained for inter-reader agreement. The signal-to-noise ratio, contrast ratio (CR), and contrast-to-noise ratio (CNR) of the median nerve were measured. The subjective ratings and quantitative measurements were compared between ncMRN and ceMRN. Results: The inter-reader agreement was excellent (k > 0.8) for all qualitative assessments and visualization assessment of each nerve segment. Compared with ncMRN, ceMRN significantly improved vascular suppression in volunteers and patients (both p < 0.001). The ceMRN significantly enhanced nerve visualization of each segment (all p < 0.05) and diagnostic confidence in volunteers and patients (both p < 0.05). The ceMRN improved lesion conspicuity (p = 0.003) in patients. Quantitatively, ceMRN had significantly higher CRs of nerve versus subcutaneous fat, bone marrow, and vessels and CNR of nerve versus vessel than ncMRN (all p < 0.05). Conclusion: The ceMRN significantly improves the visualization of peripheral nerves and pathology in the wrist and palm by robustly suppressing the signals of fat, bone marrow, and especially vessels in volunteers and patients.

Study on the improvement of magnetic resonance imaging and lesion display of small nerves in the wrist and palm using contrast agents Why was the study done? Because the nerves and branches in the wrist and palm are numerous, small, tortuous, and surrounded by muscles, fat, bones, blood vessels and other tissues, it is difficult to show their complete shape with conventional magnetic resonance imaging. Hand lesions often lead to swelling, edema and masses, which interfere with the display of nerves. Therefore, it is difficult to directly diagnose the relationship between the lesions and nerves in clinical practice. What did the researchers do? The research team used contrast agent plus three-dimensional high-resolution magnetic resonance sequence to display the nerves of volunteers and patients with hand lesions, and used subjective and objective evaluation methods to compare the display effect of the sequence on the nerves before and after the use of contrast agent. What did the researchers find? The imaging method of contrast agent plus three-dimensional high-resolution magnetic resonance sequence can reduce the interference of fat, blood vessels, etc. on nerve display, improve the display effect of each nerve segment of the wrist and palm, increase readers' confidence in identifying nerves, and improve the detection of lesions. What do the findings mean? This study verified the feasibility and advantages of using contrast agents for magnetic resonance imaging of nerves in the wrist and palm. It provides a new method for clinical and imaging diagnosis of hand lesions, which can simultaneously display the morphological characteristics of nerves and lesions, reducing the difficulty of clinical diagnosis and improving the efficiency of imaging diagnosis.

Quantitative double echo steady state T2 mapping of upper extremity peripheral nerves and muscles.

Introduction: T2 mapping can characterize peripheral neuropathy and muscle denervation due to axonal damage. Three-dimensional double echo steady-state (DESS) can simultaneously provide 3D qualitative information and T2 maps with equivalent spatial resolution. However, insufficient signal-to-noise ratio may bias DESS-T2 values. Deep learning reconstruction (DLR) techniques can reduce noise, and hence may improve quantitation of high-resolution DESS-T2. This study aims to (i) evaluate the effect of DLR methods on DESS-T2 values, and (ii) to evaluate the feasibility of using DESS-T2 maps to differentiate abnormal from normal nerves and muscles in the upper extremities, with abnormality as determined by electromyography. Methods and results: Analysis of images from 25 subjects found that DLR decreased DESS-T2 values in abnormal muscles (DLR = 37.71 ± 9.11 msec, standard reconstruction = 38.56 ± 9.44 msec, p = 0.005) and normal muscles (DLR: 27.18 ± 6.34 msec, standard reconstruction: 27.58 ± 6.34 msec, p < 0.001) consistent with a noise reduction bias. Mean DESS-T2, both with and without DLR, was higher in abnormal nerves (abnormal = 75.99 ± 38.21 msec, normal = 35.10 ± 9.78 msec, p < 0.001) and muscles (abnormal = 37.71 ± 9.11 msec, normal = 27.18 ± 6.34 msec, p < 0.001). A higher DESS-T2 in muscle was associated with electromyography motor unit recruitment (p < 0.001). Discussion: These results suggest that quantitative DESS-T2 is improved by DLR and can differentiate the nerves and muscles involved in peripheral neuropathies from those uninvolved.

Magnetic Resonance Neurography of the Lumbosacral Plexus.

Pain and weakness in the low back, pelvis, and lower extremities are diagnostically challenging, and imaging can be an important step in the workup and management of these patients. Technical advances in magnetic resonance neurography (MRN) have significantly improved its utility for imaging the lumbosacral plexus (LSP). In this article, the authors review LSP anatomy and selected pathology examples. In addition, the authors will discuss technical considerations for MRN with specific points for the branch nerves off the plexus.

Ultrasound and magnetic resonance imaging neurography assessment of diagnostic criteria in patients with carpal tunnel syndrome using electrophysiological tests as gold standard: A prospective study.

Objectives: Evaluating peripheral neuropathy mainly relies on physical examination, patient history, and electrophysiological studies. High-resolution ultrasound is a fast, noninvasive modality for dynamic nerve assessment that enables the length of the nerve to be examined. Magnetic resonance imaging is preferred for examining deeper nerves with a high contrast resolution; its use shows excellent benefit in patients with atypical presentation, equivocal diagnosis, suspected secondary causes, and postsurgical relapse. We aimed to assess the measurements and criteria for both ultrasound and magnetic resonance neurography for the diagnosis of carpal tunnel syndrome, based mainly on the three measurements assessed by Buchberger et al. Methods: This prospective study was conducted to test diagnostic accuracy. Thirty-two patients who presented clinically with, and were diagnosed by electrophysiological tests as having, carpal tunnel syndrome participated. Superficial ultrasound of the wrist joint was performed on all participants, followed by magnetic resonance imaging within 1 week of ultrasonography. Results: The three main parameters of cross-sectional area measurement, distal nerve flattening, and flexor retinaculum bowing indices showed positive occurrences of 93.7%, 59.4%, and 59.4%, respectively; 90.6% of patients had decreased nerve echotexture. The diagnostic ability of magnetic resonance imaging was decreased when cross-sectional area measurements were used: positive results were achieved in 81.2% of patients, but the positive results showing the distal tunnel nerve increased flattening and bowed flexor retinaculum slightly decreased to 56.2% for each. A high T2 signal of the median nerve was observed in 90.6% of patients. In an agreement analysis, we found a statistically significant difference that supported the use of ultrasound as a primary diagnostic modality for carpal tunnel syndrome. However, magnetic resonance imaging improved tissue characterization and was a good diagnostic modality, with a statistically significant difference, for cases of secondary carpal tunnel syndrome, detection of the underlying entrapping cause, and early abnormality detection in the innervated muscle. Conclusions: Our results demonstrate that ultrasound examination can be used as the first imaging modality after physician evaluation, with results comparable to those of electrophysiological studies for evaluating carpal tunnel syndrome and determining its cause. Magnetic resonance neurography examination is the second step in detecting secondary causes in cases with suspected early muscle denervation changes that cannot be elicited by ultrasound or in cases with equivocal results.

Phase angle of bioelectrical impedance analysis as an indicator for diabetic polyneuropathy in type 2 diabetes mellitus.

CONTEXT: Due to the heterogenous clinical symptoms and deficits, the diagnosis of diabetic polyneuropathy (DPN) is still difficult in clinical routine leading to increased morbidity and mortality. OBJECTIVE: We studied the correlation of phase angle (PhA) of bioelectrical impedance analysis (BIA) with clinical, laboratory and physical markers of DPN to evaluate PhA as possible diagnostic method for DPN. MATERIALS AND METHODS: In this cross-sectional observational study as part of the Heidelberg Study on Diabetes and Complications we examined 104 healthy individuals and 205 patients with type 2 diabetes mellitus (T2D), amongst which 63 had DPN. The PhA was calculated from multi-frequency BIA. Nerve conduction studies (NCS), quantitative sensory testing (QST) and diffusion-weighted magnetic resonance neurography (MRN) to determine fractional anisotropy (FA) reflecting peripheral nerve integrity were performed. RESULTS: T2D patients with DPN had lower PhA values (5.71 ± 0.10) compared to T2D patients without DPN (6.07 ± 0.08, p = 0.007, + 6.1%) and healthy controls (6.18 ± 0.08, p < 0.001, + 7.9%). Confounder-adjusted analyses showed correlations of the PhA with conduction velocities and amplitudes of the peroneal (ß=0.28; ß=0.31, p < 0.001) and tibial nerves (ß=0.28; ß=0.32, p < 0.001), Z-scores of QST (thermal detection ß=0.30, p < 0.05) and the FA (ß=0.60, p < 0.001). ROC analysis showed similar performance of PhA in comparison to mentioned diagnostic methods. CONCLUSION: The study shows that PhA is in comparison to other test systems used, at least an equally good and much easier to handle, investigator independent marker for detection of DPN.

Magnetic resonance neurography in spinal cord injury: Imaging findings and clinical significance.

BACKGROUND AND PURPOSE: It is unknown whether changes to the peripheral nervous system following spinal cord injury (SCI) are relevant for functional recovery or the development of neuropathic pain below the level of injury. Magnetic resonance neurography (MRN) at 3 T allows detection and localization of structural and functional nerve damage. This study aimed to combine MRN and clinical assessments in individuals with chronic SCI and nondisabled controls. METHODS: Twenty participants with chronic SCI and 20 controls matched for gender, age, and body mass index underwent MRN of the L5 dorsal root ganglia (DRG) and the sciatic nerve. DRG volume, sciatic nerve mean cross-sectional area (CSA), fascicular lesion load, and fractional anisotropy (FA), a marker for functional nerve integrity, were calculated. Results were correlated with clinical assessments and nerve conduction studies. RESULTS: Sciatic nerve CSA and lesion load were higher (21.29 ± 5.82 mm2 vs. 14.08 ± 4.62 mm2 , p < 0.001; and 8.70 ± 7.47% vs. 3.60 ± 2.45%, p < 0.001) in individuals with SCI compared to controls, whereas FA was lower (0.55 ± 0.11 vs. 0.63 ± 0.08, p = 0.022). DRG volumes were larger in individuals with SCI who suffered from neuropathic pain compared to those without neuropathic pain (223.7 ± 53.08 mm3 vs. 159.7 ± 55.66 mm3 , p = 0.043). Sciatic MRN parameters correlated with electrophysiological results but did not correlate with the extent of myelopathy or clinical severity of SCI. CONCLUSIONS: Individuals with chronic SCI are subject to a decline of structural peripheral nerve integrity that may occur independently from the clinical severity of SCI. Larger volumes of DRG in SCI with neuropathic pain support existing evidence from animal studies on SCI-related neuropathic pain.

Optimized 3D brachial plexus MR neurography using deep learning reconstruction.

OBJECTIVE: To evaluate whether 'fast,' unilateral, brachial plexus, 3D magnetic resonance neurography (MRN) acquisitions with deep learning reconstruction (DLR) provide similar image quality to longer, 'standard' scans without DLR. MATERIALS AND METHODS: An IRB-approved prospective cohort of 30 subjects (13F; mean age = 50.3 ± 17.8y) underwent clinical brachial plexus 3.0 T MRN with 3D oblique-coronal STIR-T2-weighted-FSE. 'Standard' and 'fast' scans (time reduction = 23-48%, mean = 33%) were reconstructed without and with DLR. Evaluation of signal-to-noise ratio (SNR) and edge sharpness was performed for 4 image stacks: 'standard non-DLR,' 'standard DLR,' 'fast non-DLR,' and 'fast DLR.' Three raters qualitatively evaluated 'standard non-DLR' and 'fast DLR' for i) bulk motion (4-point scale), ii) nerve conspicuity of proximal and distal suprascapular and axillary nerves (5-point scale), and iii) nerve signal intensity, size, architecture, and presence of a mass (binary). ANOVA or Wilcoxon signed rank test compared differences. Gwet's agreement coefficient (AC2) assessed inter-rater agreement. RESULTS: Quantitative SNR and edge sharpness were superior for DLR versus non-DLR (SNR by + 4.57 to + 6.56 [p < 0.001] for 'standard' and + 4.26 to + 4.37 [p < 0.001] for 'fast;' sharpness by + 0.23 to + 0.52/pixel for 'standard' [p < 0.018] and + 0.21 to + 0.25/pixel for 'fast' [p < 0.003]) and similar between 'standard non-DLR' and 'fast DLR' (SNR: p = 0.436-1, sharpness: p = 0.067-1). Qualitatively, 'standard non-DLR' and 'fast DLR' had similar motion artifact, as well as nerve conspicuity, signal intensity, size and morphology, with high inter-rater agreement (AC2: 'standard' = 0.70-0.98, 'fast DLR' = 0.69-0.97). CONCLUSION: DLR applied to faster, 3D MRN acquisitions provides similar image quality to standard scans. A faster, DL-enabled protocol may replace currently optimized non-DL protocols.

A diminished sciatic nerve structural integrity is associated with distinct peripheral sensory phenotypes in individuals with type 2 diabetes.

AIMS/HYPOTHESIS: Quantitative sensory testing (QST) allows the identification of individuals with rapid progression of diabetic sensorimotor polyneuropathy (DSPN) based on certain sensory phenotypes. Hence, the aim of this study was to investigate the relationship of these phenotypes with the structural integrity of the sciatic nerve among individuals with type 2 diabetes. METHODS: Seventy-six individuals with type 2 diabetes took part in this cross-sectional study and underwent QST of the right foot and high-resolution magnetic resonance neurography including diffusion tensor imaging of the right distal sciatic nerve to determine the sciatic nerve fractional anisotropy (FA) and cross-sectional area (CSA), both of which serve as markers of structural integrity of peripheral nerves. Participants were then assigned to four sensory phenotypes (participants with type 2 diabetes and healthy sensory profile [HSP], thermal hyperalgesia [TH], mechanical hyperalgesia [MH], sensory loss [SL]) by a standardised sorting algorithm based on QST. RESULTS: Objective neurological deficits showed a gradual increase across HSP, TH, MH and SL groups, being higher in MH compared with HSP and in SL compared with HSP and TH. The number of participants categorised as HSP, TH, MH and SL was 16, 24, 17 and 19, respectively. There was a gradual decrease of the sciatic nerve's FA (HSP 0.444, TH 0.437, MH 0.395, SL 0.382; p=0.005) and increase of CSA (HSP 21.7, TH 21.5, MH 25.9, SL 25.8 mm2; p=0.011) across the four phenotypes. Further, MH and SL were associated with a lower sciatic FA (MH unstandardised regression coefficient [B]=-0.048 [95% CI -0.091, -0.006], p=0.027; SL B=-0.062 [95% CI -0.103, -0.020], p=0.004) and CSA (MH ß=4.3 [95% CI 0.5, 8.0], p=0.028; SL B=4.0 [95% CI 0.4, 7.7], p=0.032) in a multivariable regression analysis. The sciatic FA correlated negatively with the sciatic CSA (r=-0.35, p=0.002) and markers of microvascular damage (high-sensitivity troponin T, urine albumin/creatinine ratio). CONCLUSIONS/INTERPRETATION: The most severe sensory phenotypes of DSPN (MH and SL) showed diminishing sciatic nerve structural integrity indexed by lower FA, likely representing progressive axonal loss, as well as increasing CSA of the sciatic nerve, which cannot be detected in individuals with TH. Individuals with type 2 diabetes may experience a predefined cascade of nerve fibre damage in the course of the disease, from healthy to TH, to MH and finally SL, while structural changes in the proximal nerve seem to precede the sensory loss of peripheral nerves and indicate potential targets for the prevention of end-stage DSPN. TRIAL REGISTRATION: ClinicalTrials.gov NCT03022721.

Multimodality imaging review of ulnar nerve pathologies.

The ulnar nerve is the second most commonly entrapped nerve after the median nerve. Although clinical evaluation and electrodiagnostic studies remain widely used for the evaluation of ulnar neuropathy, advancements in imaging have led to increased utilization of these newer / better imaging techniques in the overall management of ulnar neuropathy. Specifically, high-resolution ultrasonography of peripheral nerves as well as MRI has become quite useful in evaluating the ulnar nerve in order to better guide treatment. The caliber and fascicular pattern identified in the normal ulnar nerves are important distinguishing features from ulnar nerve pathology. The cubital tunnel within the elbow and Guyon's canal within the wrist are important sites to evaluate with respect to ulnar nerve compression. Both acute and chronic conditions resulting in deformity, trauma as well as inflammatory conditions may predispose certain patients to ulnar neuropathy. Granulomatous diseases as well as both neurogenic and non-neurogenic tumors can also potentially result in ulnar neuropathy. Tumors around the ulnar nerve can also lead to mass effect on the nerve, particularly in tight spaces like the aforementioned canals. Although high-resolution ultrasonography is a useful modality initially, particularly as it can be helpful for dynamic evaluation, MRI remains most reliable due to its higher resolution. Newer imaging techniques like sonoelastography and microneurography, as well as nerve-specific contrast agents, are currently being investigated for their usefulness and are not routinely being used currently.

MRI-based radiomics features uncover the micro-change of dorsal root ganglia lesion for patients with post-herpetic neuralgia.

Objective: To create and authenticate MRI-based radiomic signatures to identify dorsal root ganglia (DRG) lesions in post-herpetic neuralgia (PHN) patients generalizable and interpretable. Method: This prospective diagnostic study was conducted between January 2021 and February 2022. Lesioned DRG in patients with PHN and normal DRG in age-, sex-, height-, and weight-matched healthy controls were selected for assessment and divided into two groups (8:2) randomly: training and testing sets. The least absolute shrinkage and selection operator algorithm was employed to generate feature signatures and construct a model, followed by the assessment of model efficacy using the area under the curve (AUC) of the receiver operating characteristic (ROC), as well as sensitivity and specificity metrics. Results: The present investigation involved 30 patients diagnosed with postherpetic neuralgia (PHN), consisting of 18 males and 12 females (mean age 60.70 ± 10.18 years), as well as 30 healthy controls, comprising 18 males and 12 females (mean age 58.13 ± 10.54 years). A total of 98 DRG were randomly divided into two groups (8:2), namely a training set (n = 78) and a testing set (n = 20). Five radiomic features were chosen to construct the models. In the training dataset, the area under the curve (AUC) was 0.847, while the sensitivity and specificity were 71.79 and 97.44%, respectively. In the test dataset, the AUC was 0.87, and the sensitivity and specificity were 80.00 and 100.00%, respectively. Conclusion: An MRI-based radiomic signatures model has the capacity to uncover the micro-change of damaged DRG in individuals afflicted with postherpetic neuralgia.

Three-dimensional magnetic resonance neurography aids in detection of brachial plexus nerve root signal and size alterations in patients with amyotrophic lateral sclerosis: a case-control study.

Background: Since previous histopathological studies have shown a distal to proximal gradient of axonal damage in peripheral nerves of patients with amyotrophic lateral sclerosis (ALS), it would be worthwhile to evaluate consequence of such changes on magnetic resonance imaging (MRI). The aim of this study was to assess proximal-distal longitudinal signal and size alterations of brachial plexus nerve roots in ALS patients using 3-dimensional (3D) magnetic resonance neurography (MRN). Methods: A total of 21 ALS patients and 19 controls were evaluated. The diameters and signal-to-noise (SNR) ratio values of C5-C8 roots were measured at five points from proximal to distal sites. Student's t-test was performed to compare the differences at each point between two groups. Linear regression was performed for each nerve root, and the differences in linear regression slopes between two groups were analyzed. Receiver operating characteristic (ROC) analysis was performed for the diameter and SNR value ratio of the distal to the proximal points. Results: Interobserver agreement was excellent [intraclass correlation coefficient (ICC): 0.802-0.913]. The diameters and SNR values of C5-C8 roots showed a significant decrease (P<0.05) from proximal to distal except SNR value of C5 root in controls. The slope values of diameters in ALS were -0.01924 for C5, -0.04404 for C6, -0.06228 for C7, and -0.06464 for C8. The slope values of SNR values in ALS were -10.14 for C5, -12.86 for C6, -15.99 for C7, and -19.06 for C8. The slope of nerve diameters and SNR values for ALS patients were more negatively sloped than controls (P<0.05) except SNR values of C5 and C7 roots. The ROC analysis confirmed that the diameter and SNR value ratio could differentiate ALS patients from controls with high accuracy. The cutoff values of diameter ratio were 0.7418 for C5, 0.6952 for C6, 0.6431 for C7, and 0.7147 for C8. The cutoff values of SNR value ratio were 0.5989 for C5, 0.6516 for C6, 0.6065 for C7, and 0.6758 for C8. Conclusions: Proximal-distal longitudinal diameters and SNR values decreased significantly for brachial plexus nerve roots in ALS patients with larger differences in slopes compared to controls. These results reflect pathophysiological changes of ALS and may be helpful in improving the diagnosis of ALS.

[Diagnostics and treatment of hourglass-like nerve constrictions and torsions in neuralgic amyotrophy]. / Diagnostik und Therapie sanduhrförmiger Nervenstrikturen und -torsionen bei neuralgischer Amyotrophie.

Neuralgic amyotrophy is a disease of the peripheral nervous system characterized by severe neuropathic pain followed by peripheral paralysis. A distinction is made between a hereditary and an idiopathic form, which is assumed to have an autoimmunological origin. Conservative medicinal treatment mainly consists of nonsteroidal anti-inflammatory drugs (NSAID), opioids and glucocorticoids; however, despite treatment, symptoms in the form of pain or paralysis persist in over 50% of cases. Inflammation can lead to strictures and torsions of peripheral nerves, which can be visualized by imaging using nerve sonography or magnetic resonance (MR) neurography and confirmed intraoperatively during surgical exploration. Based on the currently available data, patients with strictures and torsions of peripheral nerves can benefit from neurosurgical treatment.