Nerve Imaging Research Articles

Transformative imaging of the extracranial facial nerve by MRI and Microsoft HoloLens2

Introduction: The facial nerve is a small structure that can be displaced into unexpected positions by tumors growing within the parotid gland. Hololens2 is an augmented reality headset which allows the holographic projection of images onto the wearers view of their surroundings creating a mixed image. In this study we assessed the ability of 3T MRI and Hololens2 to visualise the path of facial nerve around parotid tumors and the impact on surgical planning. Methods: 18 patients with parotid neoplasms underwent 3T MRI imaging. MRI images were subsequently segmented using 3D slicer software and uploaded into a mixed reality device (Microsoft HoloLens2) using ApoQlar software. This created a 3D hologram of the facial nerve and the relations to the surrounding structure.Images were later compared to observations made intraoperatively. Results: 18 patients with parotid neoplasms were included in this study. 14 females and 4 males between the ages of 18 and 66. This included 13 benign and 5 malignant neoplasms. Identical match of projected 3D hologram images to the surgical findings was present in 100% of the patients. Age, sex, tumor type, size, site did not make a change in the predicted images. Conclusions: The facial nerve can be faithfully visually traced in 3D hologram as it passes through the parotid gland and weaves its way past resident tumors. This allows surgeons to be forewarned of unusual configuration of the facial nerve and also opens up the opportunity to plan and execute operations in a way that minimizes nerve contact. Introduction: The facial nerve is a small structure that can be displaced into unexpected positions by tumors growing within the parotid gland. Hololens2 is an augmented reality headset which allows the holographic projection of images onto the wearers view of their surroundings creating a mixed image. In this study we assessed the ability of 3T MRI and Hololens2 to visualise the path of facial nerve around parotid tumors and the impact on surgical planning. Methods: 18 patients with parotid neoplasms underwent 3T MRI imaging. MRI images were subsequently segmented using 3D slicer software and uploaded into a mixed reality device (Microsoft HoloLens2) using ApoQlar software. This created a 3D hologram of the facial nerve and the relations to the surrounding structure.Images were later compared to observations made intraoperatively. Results: 18 patients with parotid neoplasms were included in this study. 14 females and 4 males between the ages of 18 and 66. This included 13 benign and 5 malignant neoplasms. Identical match of projected 3D hologram images to the surgical findings was present in 100% of the patients. Age, sex, tumor type, size, site did not make a change in the predicted images. Conclusions: The facial nerve can be faithfully visually traced in 3D hologram as it passes through the parotid gland and weaves its way past resident tumors. This allows surgeons to be forewarned of unusual configuration of the facial nerve and also opens up the opportunity to plan and execute operations in a way that minimizes nerve contact.

Research on application of spatial attention mechanism in the super-resolution reconstruction of single-channel greyscale image of mouse brain

High-resolution medical images are an essential basis for scientific research and clinical judgment. At this stage, saq is still limited by the hardware conditions of imaging equipment and the generalisation of imaging methods. An economical method would involve the application of Single Image Super-Resolution (SISR) technology in the acquisition of high-resolution images in the biomedical field. Based on the classic super-resolution network, the cascaded residual plate aimed at CARN is examined into in this study. Regarding the problem of the insufficient feature learning process, the sSE module of spatial incentives was introduced, and the network structure of CARN was optimised. The mouse brain nerve image reconstructed by the CARN-L algorithm is significantly improved compared with the original image.

Role of Ultrasonography and Strain Elastography Findings in Peripheral Nerve Sheath Tumor

Peripheral nerve imaging science is rapidly advancing, for early and robust diagnosis of many ill-health conditions, especially in detection of tumors. Radiological imaging techniques provide dynamic, real-time assessment of anatomy which either can help in diagnosis or prognosis in peripheral nerve disorders. Peripheral nerve tumors are often evaluated with magnetic resonance imaging, although there are many advantages offered with ultrasonography (USG). Strain elastography (SE), another technique, is well known for the diagnosis of soft-tissue tumors and is used to evaluate tissue stiffness. Hard lesions are more resistant to extrinsic compression and show smaller strain, whereas soft lesions show larger strain. The narrative review provides insight in functioning and utility of USG and SE techniques in peripheral nerve sheath tumor diagnosis.

Multi-scale Multi-structure Siamese Network (MMSNet) for Primary Open-Angle Glaucoma Prediction.

Primary open-angle glaucoma (POAG) is one of the leading causes of irreversible blindness in the United States and worldwide. POAG prediction before onset plays an important role in early treatment. Although deep learning methods have been proposed to predict POAG, these methods mainly focus on current status prediction. In addition, all these methods used a single image as input. On the other hand, glaucoma specialists determine a glaucomatous eye by comparing the follow-up optic nerve image with the baseline along with supplementary clinical data. To simulate this process, we proposed a Multi-scale Multi-structure Siamese Network (MMSNet) to predict future POAG event from fundus photographs. The MMSNet consists of two side-outputs for deep supervision and 2D blocks to utilize two-dimensional features to assist classification. The MMSNet network was trained and evaluated on a large dataset: 37,339 fundus photographs from 1,636 Ocular Hypertension Treatment Study (OHTS) participants. Extensive experiments show that MMSNet outperforms the state-of-the-art on two "POAG prediction before onset" tasks. Our AUC are 0.9312 and 0.9507, which are 0.2204 and 0.1490 higher than the state-of-the-art, respectively. In addition, an ablation study is performed to check the contribution of different components. These results highlight the potential of deep learning to assist and enhance the prediction of future POAG event. The proposed network will be publicly available on https://github.com/bionlplab/MMSNet.

The Role of Artificial Intelligence in the Diagnosis and Management of Glaucoma.

Glaucomatous optic neuropathy is the leading cause of irreversible blindness worldwide. Diagnosis and monitoring of disease involves integrating information from the clinical examination with subjective data from visual field testing and objective biometric data that includes pachymetry, corneal hysteresis, and optic nerve and retinal imaging. This intricate process is further complicated by the lack of clear definitions for the presence and progression of glaucomatous optic neuropathy, which makes it vulnerable to clinician interpretation error. Artificial intelligence (AI) and AI-enabled workflows have been proposed as a plausible solution. Applications derived from this field of computer science can improve the quality and robustness of insights obtained from clinical data that can enhance the clinician's approach to patient care. This review clarifies key terms and concepts used in AI literature, discusses the current advances of AI in glaucoma, elucidates the clinical advantages and challenges to implementing this technology, and highlights potential future applications.

Optic disc cupping after circumpapillary Pd-103 slotted plaque radiation therapy

ObjectifExaminer les effets vasculaires et morphologiques sur le disque optique après une radiothérapie par plaque fendue dans le traitement d'un mélanome choroïdien touchant le disque optique. NatureÉtude transversale rétrospective. ParticipantsTrente-neuf patients atteints d'un mélanome choroïdien touchant le nerf optique. MéthodesChaque mélanome a été traité au moyen d'une plaque radioactive fendue (palladium-103) incluant et/ou entourant la gaine du nerf optique entre 2005 et 2019. Les images du nerf optique avant et après la radiothérapie ont permis de documenter et d’évaluer les changements au chapitre de la pâleur du nerf optique et du rapport cupule/disque (C/D). On a mesuré le rapport C/D à la tomographie par cohérence optique (OCT) de même que la pression intraoculaire (PIO) avant le traitement et pendant le suivi, et 22 patients ont également fait l'objet d'une angiographie-tomographie par cohérence optique (OCT-A) dont la qualité des images permettait l’évaluation de la densité et de la longueur des vaisseaux sanguins. On a noté une corrélation entre les différences quant aux mesures du rapport C/D et les modifications de la densité et de la longueur des vaisseaux sanguins visibles à l'OCT-A. RésultatsSuivant une radiothérapie par plaque fendue, on n'a pas observé de hausse significative de la PIO ni d'augmentation de la pâleur du nerf optique. Les images OCT et les photographies couleur ont mis au jour une augmentation significative (p < 0,001 pour les 2 techniques) du rapport C/D à la fin du suivi, comparativement à ce qui avait été mesuré avant le traitement. On notait une corrélation significative entre la hausse du rapport C/D selon l'OCT et les variations de la longueur des vaisseaux sanguins mesurées à l'OCT-A (p = 0,027). De même, on a établi une corrélation significative entre une augmentation du rapport C/D dans les photographies du fond d’œil et les variations de la densité (p = 0,043) et de la longueur (p = 0,019) des vaisseaux sanguins mesurées à l'OCT-A. ConclusionLes photographies du fond d’œil et les images OCT ont mis en lumière une augmentation du phénomène d'excavation du disque optique au décours d'une radiothérapie par plaque fendue. L'excavation était associée à une occlusion et à une atténuation vasculaires progressives synchrones de la zone péripapillaire, visibles à l'OCT-A. On en conclut que l'ischémie péripapillaire et papillaire due à la radiothérapie par plaque fendue s'accompagne d'une hausse du rapport C/D et d'une aggravation de l'excavation du disque optique.

In Vivo Cellular-Level 3D Imaging of Peripheral Nerves Using a Dual-Focusing Technique for Intra-Neural Interface Implantation.

In vivo volumetric imaging of the microstructural changes of peripheral nerves with an inserted electrode could be key for solving the chronic implantation failure of an intra‐neural interface necessary to provide amputated patients with natural motion and sensation. Thus far, no imaging devices can provide a cellular‐level three‐dimensional (3D) structural images of a peripheral nerve in vivo. In this study, an optical coherence tomography‐based peripheral nerve imaging platform that employs a newly proposed depth of focus extension technique is reported. A point spread function with the finest transverse resolution of 1.27 µm enables the cellular‐level volumetric visualization of the metal wire and microstructural changes in a rat sciatic nerve with the metal wire inserted in vivo. Further, the feasibility of applying the imaging platform to large animals for a preclinical study is confirmed through in vivo rabbit sciatic nerve imaging. It is expected that new possibilities for the successful chronic implantation of an intra‐neural interface will open up by providing the 3D microstructural changes of nerves around the inserted electrode.

Assessing Lumbar Plexus and Sciatic Nerve Damage in Relapsing-Remitting Multiple Sclerosis Using Magnetisation Transfer Ratio.

Background: Multiple sclerosis (MS) has traditionally been regarded as a disease confined to the central nervous system (CNS). However, neuropathological, electrophysiological, and imaging studies have demonstrated that the peripheral nervous system (PNS) is also involved, with demyelination and, to a lesser extent, axonal degeneration representing the main pathophysiological mechanisms.Aim: The purpose of this study was to assess PNS damage at the lumbar plexus and sciatic nerve anatomical locations in people with relapsing-remitting MS (RRMS) and healthy controls (HCs) in vivo using magnetisation transfer ratio (MTR), which is a known imaging biomarker sensitive to alterations in myelin content in neural tissue, and not previously explored in the context of PNS damage in MS.Method: Eleven HCs (7 female, mean age 33.6 years, range 24-50) and 15 people with RRMS (12 female, mean age 38.5 years, range 30-56) were recruited for this study and underwent magnetic resonance imaging (MRI) investigations together with clinical assessments using the expanded disability status scale (EDSS). Magnetic resonance neurography (MRN) was first used for visualisation and identification of the lumbar plexus and the sciatic nerve and MTR imaging was subsequently performed using identical scan geometry to MRN, enabling straightforward co-registration of all data to obtain global and regional mean MTR measurements. Linear regression models were used to identify differences in MTR values between HCs and people with RRMS and to identify an association between MTR measures and EDSS.Results: MTR values in the sciatic nerve of people with RRMS were found to be significantly lower compared to HCs, but no significant MTR changes were identified in the lumbar plexus of people with RRMS. The median EDSS in people with RRMS was 2.0 (range, 0-3). No relationship between the MTR measures in the PNS and EDSS were identified at any of the anatomical locations studied in this cohort of people with RRMS.Conclusion: The results from this study demonstrate the presence of PNS damage in people with RRMS and support the notion that these changes, suggestive of demyelination, maybe occurring independently at different anatomical locations within the PNS. Further investigations to confirm these findings and to clarify the pathophysiological basis of these alterations are warranted.

Intracompartmental pressure in lower leg muscles and tibial nerve in healthy volunteers correlate to the stiffness measured using shear wave elastography

BackgroundAcute compartment syndrome in the lower leg is a painful condition characterized by an increase in intracompartmental pressure. To prevent misdiagnosis and delay in the recognition of the condition, which can lead to severe complications, continuous monitoring of intracompartmental pressure for at least 24 h. from the onset of initial symptoms has been recommended. The purpose of the current study was to establish shear wave elastography as a potential imaging biomarker for the observed increase in pressure in four compartments of the lower leg. MethodsEighteen healthy participants (9 males) without any injury in their leg muscles were recruited for the study after internal review board approval. Subjects were instructed to sit on a table and pressures at 60, 90, and 120 mmHg were applied using a pressure cuff placed above the proximal pole of the patella. Shear wave elastography-measured stiffness outcomes at baseline (0 mmHg) and at each cuff pressure level were obtained from the tibialis anterior, the peroneus longs, gastrocnemius medialis, and tibialis posterior muscles, as well as the tibial nerve. FindingsSpearman's rank correlation coefficient showed strong correlations between shear wave elastography-measured stiffness from all four muscles and cuff pressure levels (r > 0.80, P < 0.05). Stiffness from the tibial nerve was also significantly correlated with cuff pressure levels (r > 0.99, P < 0.05). InterpretationShear wave elastography imaging of lower leg muscles and nerve can be useful to non-invasively monitor intracompartmental pressure in patients suspected of acute compartment syndrome.

Artificial intelligence utilising corneal confocal microscopy for the diagnosis of peripheral neuropathy in diabetes mellitus and prediabetes

Aims/hypothesisWe aimed to develop an artificial intelligence (AI)-based deep learning algorithm (DLA) applying attribution methods without image segmentation to corneal confocal microscopy images and to accurately classify peripheral neuropathy (or lack of).MethodsThe AI-based DLA utilised convolutional neural networks with data augmentation to increase the algorithm’s generalisability. The algorithm was trained using a high-end graphics processor for 300 epochs on 329 corneal nerve images and tested on 40 images (1 image/participant). Participants consisted of healthy volunteer (HV) participants (n = 90) and participants with type 1 diabetes (n = 88), type 2 diabetes (n = 141) and prediabetes (n = 50) (defined as impaired fasting glucose, impaired glucose tolerance or a combination of both), and were classified into HV, those without neuropathy (PN−) (n = 149) and those with neuropathy (PN+) (n = 130). For the AI-based DLA, a modified residual neural network called ResNet-50 was developed and used to extract features from images and perform classification. The algorithm was tested on 40 participants (15 HV, 13 PN−, 12 PN+). Attribution methods gradient-weighted class activation mapping (Grad-CAM), Guided Grad-CAM and occlusion sensitivity displayed the areas within the image that had the greatest impact on the decision of the algorithm.ResultsThe results were as follows: HV: recall of 1.0 (95% CI 1.0, 1.0), precision of 0.83 (95% CI 0.65, 1.0), F1-score of 0.91 (95% CI 0.79, 1.0); PN−: recall of 0.85 (95% CI 0.62, 1.0), precision of 0.92 (95% CI 0.73, 1.0), F1-score of 0.88 (95% CI 0.71, 1.0); PN+: recall of 0.83 (95% CI 0.58, 1.0), precision of 1.0 (95% CI 1.0, 1.0), F1-score of 0.91 (95% CI 0.74, 1.0). The features displayed by the attribution methods demonstrated more corneal nerves in HV, a reduction in corneal nerves for PN− and an absence of corneal nerves for PN+ images.Conclusions/interpretationWe demonstrate promising results in the rapid classification of peripheral neuropathy using a single corneal image. A large-scale multicentre validation study is required to assess the utility of AI-based DLA in screening and diagnostic programmes for diabetic neuropathy.Graphical abstract

Advances in Imaging of Subbasal Corneal Nerves With Micro-Optical Coherence Tomography.

PurposeTo investigate the most peripheral corneal nerve plexus using high-resolution micro–optical coherence tomography (µOCT) imaging and to assess µOCT's clinical potential as a screening tool for corneal and systemic diseases.MethodsAn experimental high-resolution (1.5 × 1.5 × 1 µm) µOCT setup was applied for three-dimensional imaging of the subbasal nerve plexus in nonhuman primates (NHPs) and swine within 3 hours postmortem. Morphologic features of subbasal nerves in µOCT were compared to β3 tubulin-stained fluorescence confocal microscopy (FCM). Parameters such as nerve density, nerve distribution, and imaging repeatability were evaluated, using semiautomatic image analysis in form of a custom corneal surface segmentation algorithm and NeuronJ.ResultsSwine and NHP corneas showed the species-specific nerve morphology in both imaging modalities. Most fibers showed a linear course, forming a highly parallel pattern, converging in a vortex with overall nerve densities varying between 9.51 and 24.24 mm/mm2. The repeatability of nerve density quantification of the µOCT scans as approximately 88% in multiple image recordings of the same cornea.ConclusionsCompared to the current gold standard of FCM, µOCT's larger field of view of currently 1 × 1 mm increases the conclusiveness of density measurements, which, coupled with µOCT's feature of not requiring direct contact, shows promise for future clinical application. The nerve density quantification may be relevant for screening for systemic disease (e.g., peripheral neuropathy).Translational RelevanceTechnological advances in OCT technology may enable a quick assessment of corneal nerve density, which could be valuable evaluating ophthalmic and systemic peripheral innervation.

Influence of temperature on sonographic images of the median nerve for the diagnosis of carpal tunnel syndrome: a case control study

BackgroundIn addition to nerve conduction studies (NCSs), ultrasonography has been widely used as an alternative tool for diagnosing carpal tunnel syndrome (CTS). Although the results of NCSs are influenced by local skin temperature, few studies have explored the effects of skin temperature on ultrasonography of the median nerve. Since swelling and intraneural blood flow of the median nerve might be influenced by local temperature changes, the aim of this study was to evaluate the cross-sectional area (CSA) and intraneural blood flow of the median nerve under three skin temperatures (30 °C, 32 °C, 34 °C).MethodsFifty patients with CTS and 50 healthy volunteers were consecutively recruited from a community hospital. Each participant received physical examinations and NCSs and underwent ultrasonography, including power Doppler, to evaluate intraneural vascularity.ResultsThe CSA of the median nerve in the CTS patients was significantly larger than that in the healthy controls at all three temperatures. However, significant differences in the power Doppler signals of the median nerve between the two studied groups were observed only at 30 and 32 °C, not at 34 °C.ConclusionThe significant difference in the intraneural vascularity of the median nerve between the patients with CTS and the healthy subjects was lost at higher temperatures (34 °C). Therefore, the results of power Doppler ultrasonography in diagnosing CTS should be cautiously interpreted in patients with a high skin temperature or those who reside in warm environments.

Early corneal and optic nerve changes in a paediatric population affected by obstructive sleep apnea syndrome.

The relation between OSAS and eye diseases is well known in adults, while very few and contradictory data can be found regarding paediatric ages. The aim of this study is to explore the early corneal, macular and optic nerve changes in paediatric patients with OSAS. Prospective study that enrolled children aged ≥ 4years referred to the Paediatric Pneumology Clinic in Verona for suspected obstructive sleep apnoea syndrome (OSAS) and investigated with the overnight respiratory polygraphy. Patients with apnoea-hypopnea index (AHI) > 1 were classified as OSAS, while those with AHI < 1 were classified non-OSAS. All patients underwent comprehensive eye examination including slit lamp, refraction, intraocular pression (Goldman applanation tonometry), corneal tomography (corneal astigmatism, corneal keratometry at the apex, surface asymmetry index, central corneal thickness and thinnest corneal thickness) and optical coherence tomography (central macular thickness, macular volume and retinal nerve fibre layer). Seventy-two children were enrolled in the study. The overall prevalence of OSAS was 48.6%. Statistically significant differences were found between OSAS and non-OSAS group for corneal asymmetry (0.9 ± 0.5 and 0.6 ± 0.3, respectively; p = 0.02), thinnest corneal thickness (551.8 ± 33.9 and 563.7 ± 32.5; p = 0.04), average retinal nerve fibre layer (102.8 ± 10.5µm and 98.1 ± 12.3µm; p = 0.012) and in nasal quadrant (76.2 ± 15.4µm and 66.5 ± 12.6µm; p = 0.0002). A comprehensive eye examination with corneal and optic nerve imaging showed early corneal and optic nerve changes in children newly diagnosed with OSAS. These could be prelude of the known ocular manifestations associated with OSAS in adult patients.

New and Advanced Magnetic Resonance Imaging Diagnostic Imaging Techniques in the Evaluation of Cranial Nerves and the Skull Base.

The skull base and cranial nerves are technically challenging to evaluate using magnetic resonance (MR) imaging, owing to a combination of anatomic complexity and artifacts. However, improvements in hardware, software and sequence development seek to address these challenges. This section will discuss cranial nerve imaging, with particular attention to the techniques, applications and limitations of MR neurography, diffusion tensor imaging and tractography. Advanced MR imaging techniques for skull base pathology will also be discussed, including diffusion-weighted imaging, perfusion and permeability imaging, with a particular focus on practical applications.

Comparison of imaging parameters between OCT, GDx and HRT in the Northern Finland birth cohort eye study.

The purpose of the study was to assess and compare the optic nerve head (ONH) and retinal nerve fibre layer (RNFL) parameters and image quality parameters obtained by Cirrus HD-OCT, GDxECC and HRT3 in a population-based screening study. This analysis examined 2566 subjects taking part in the Northern Finland Birth Cohort Eye study. Images with spectral domain OCT (Cirrus HD-OCT 4000), scanning laser ophthalmoscopy (HRT3) and scanning laser polarimetry (GDxECC) were obtained from each subject. The correlation of average and regional parameters of RNFL and ONH between devices was evaluated. The RNFL thickness was 90.9 µm when measured with OCT, 24.6 µm with HRT and 48.1 µm with GDx. There was a high correlation between the disc and cup measurements with the HRT and OCT and the RNFL thickness of the OCT and GDx (r > 0.5). A statistically significant correlation was found between RNFL measurements of the HRT and OCT in the superior, temporal and inferior quadrants. Optical coherence tomography (OCT) signal strength correlated with the image quality parameters of the HRT and GDx. The percentage of good quality images was the lowest with the GDx. The RNFL thickness in Northern Finland birth cohort was at a lower level compared to other studies. The study confirms the difference in measuring ONH parameters between the imaging devices. However, significant correlations between devices were found in the cup volume and cup disc area ratio parameters of the OCT and HRT. The correlations between image quality parameters and glaucoma detection parameters were relatively low.

Automated Segmentation of Median Nerve in Dynamic Sonography Using Deep Learning: Evaluation of Model Performance.

There is an emerging trend to employ dynamic sonography in the diagnosis of entrapment neuropathy, which exhibits aberrant spatiotemporal characteristics of the entrapped nerve when adjacent tissues move. However, the manual tracking of the entrapped nerve in consecutive images demands tons of human labors and impedes its popularity clinically. Here we evaluated the performance of automated median nerve segmentation in dynamic sonography using a variety of deep learning models pretrained with ImageNet, including DeepLabV3+, U-Net, FPN, and Mask-R-CNN. Dynamic ultrasound images of the median nerve at across wrist level were acquired from 52 subjects diagnosed as carpal tunnel syndrome when they moved their fingers. The videos of 16 subjects exhibiting diverse appearance and that of the remaining 36 subjects were used for model test and training, respectively. The centroid, circularity, perimeter, and cross section area of the median nerve in individual frame were automatically determined from the inferred nerve. The model performance was evaluated by the score of intersection over union (IoU) between the annotated and model-predicted data. We found that both DeepLabV3+ and Mask R-CNN predicted median nerve the best with averaged IOU scores close to 0.83, which indicates the feasibility of automated median nerve segmentation in dynamic sonography using deep learning.

Glymphatic imaging and modulation of the optic nerve.

Optic nerve health is essential for proper function of the visual system. However, the pathophysiology of certain neurodegenerative disease processes affecting the optic nerve, such as glaucoma, is not fully understood. Recently, it was hypothesized that a lack of proper clearance of neurotoxins contributes to neurodegenerative diseases. The ability to clear metabolic waste is essential for tissue homeostasis in mammals, including humans. While the brain lacks the traditional lymphatic drainage system identified in other anatomical regions, there is growing evidence of a glymphatic system in the central nervous system, which structurally includes the optic nerve. Named to acknowledge the supportive role of astroglial cells, this perivascular fluid drainage system is essential to remove toxic metabolites from the central nervous system. Herein, we review existing literature describing the physiology and dysfunction of the glymphatic system specifically as it relates to the optic nerve. We summarize key imaging studies demonstrating the existence of a glymphatic system in the optic nerves of wild-type rodents, aquaporin 4-null rodents, and humans; glymphatic imaging studies in diseases where the optic nerve is impaired; and current evidence regarding pharmacological and lifestyle interventions that may help promote glymphatic function to improve optic nerve health. We conclude by highlighting future research directions that could be applied to improve imaging detection and guide therapeutic interventions for diseases affecting the optic nerve.

Novel [18F]-Labeled Meta-Bromobenzylguanidine Derivatives: Potential Positron Emission Tomography Imaging Probes for the Norepinephrine Transporter.

To develop novel norepinephrine transporter (NET)-targeting positron emission tomography (PET) probes with optimal pharmacokinetic properties, a series of meta-bromobenzylguanidine derivatives was synthesized. 4-Fluorodiethoxyethane-3-bromobenzylguanidine (compound 12) showed relatively good affinity for the NET (IC50 = 1.00 ± 0.04 μM). The corresponding radiotracer 18F-12 was prepared in high radiochemical purity (>98%) via a three-step method. The in vitro cellular uptake results demonstrated that 18F-12 was specifically taken up by NET-expressing SK-N-SH cells by the uptake-1 mechanism. Biodistribution studies in mice showed that 18F-12 exhibited high cardiac uptake (10.45 ± 0.66 %ID/g at 5 min p.i. and 6.44 ± 0.40 %ID/g at 120 min p.i.), faster liver clearance, and a lower dose of absorbed radiation than [123I]-labeled meta-iodobenzylguanidine ([123I]MIBG). Small animal PET imaging confirmed the high heart-to-background ratio of 18F-12 and the uptake-1 mechanism specific for the NET in rats, indicating its potential as a promising PET radiotracer for cardiac sympathetic nerve imaging.

Pure Neuritic Leprosy with Bilateral Foot Drop and Central Nervous Involvement: A Clinical, Electrophysiological, and MR Correlation.

Central nervous system (CNS) involvement in leprosy is sparsely documented. Neurophysiological tests and magnetic resonance imaging (MRI) helps in demonstrating CNS involvement in the patient of pure neuritic leprosy. To demonstrate CNS involvement in pure neuritic leprosy. Detailed clinical presentation and skin lesions were evaluated. Sural nerve biopsy, MRI diffusion tensor imaging of spinal cord and optic nerve were performed. Visual evoked potential and tibial somatosensory evoked potential were done. Their clinical, electrophysiological, and MRI were done at follow-up visits. We report three patients of pure neuritic leprosy with bilateral foot drop as the initial presentation. MRI T2W sequence of cervico dorsal cord showed dorsal column hyperintensity in two patients. Diffusion-weighted MR revealed decrease fractional anisotropy and an increase in the apparent diffusion coefficient. Similar findings were also noted in the optic nerves. The patients were managed with multidrug therapy multibacillary regimen and steroid in tapering dose. At follow-up, they showed clinical improvement in vision and power of ankle dorsiflexor. Patients of pure neuritic leprosy may manifest with bilateral foot drop with the involvement of posterior column and cranial nerves.

Variability in electrodiagnostic findings associated with neurogenic thoracic outlet syndrome.

Introduction/AimsNeurogenic thoracic outlet syndrome (NTOS) is a heterogeneous and often disputed entity. An electrodiagnostic pattern of T1 > C8 axon involvement is considered characteristic for the diagnosis of NTOS. However, since the advent of high‐resolution nerve ultrasound (US) imaging, we have encountered several patients with a proven entrapment of the lower brachial plexus who showed a different, variable electrodiagnostic pattern.MethodsIn this retrospective case series, 14 patients with an NTOS diagnosis with a verified source of compression of the lower brachial plexus and abnormal findings on their electrodiagnostic testing were included. Their medical records were reviewed to obtain clinical, imaging, and electrodiagnostic data.ResultsSeven patients showed results consistent with the “classic” T1 axon > C8 pattern of involvement. Less typical findings included equally severe involvement of T1 and C8 axons, more severe C8 involvement, pure motor abnormalities, neurogenic changes on needle electromyography in the flexor carpi radialis and biceps brachii muscles, and one patient with an abnormal sensory nerve action potential (SNAP) amplitude for the median sensory response recorded from the third digit. Patients with atypical findings on electrodiagnostic testing underwent nerve imaging more often compared to patients with classic findings (seven of seven patients vs. five of seven respectively), especially nerve ultrasound.DiscussionWhen there is a clinical suspicion of NTOS, an electrodiagnostic finding other than the classic T1 > C8 pattern of involvement does not rule out the diagnosis. High resolution nerve imaging is valuable to diagnose additional patients with this treatable condition.