Optic Nerve Diameter Research Articles

Non-invasive estimation of cerebrospinal fluid pressure in idiopathic intracranial hypertension: magnetic resonance imaging analysis of optic nerve and eyeball.

Invasive methods such as lumbar puncture and intraventricular catheters are commonly used to measure intracranial pressure (ICP). This study aims to develop quantitative and non-invasive techniques to measure ICP in patients with Idiopathic Intracranial Hypertension (IIH) using magnetic resonance imaging (MRI) findings. MRI data obtained from 50 patients with IIH and 30 age- and sex- matched controls were analyzed and optic nerve sheath diameter (ONSD), eyeball transverse diameter (ETD) and optic nerve diameter (OND) were measured. ONSD, ONSD/ETD and OND/ONSD indexes were calculated according to different ONSD measurement distances. Correlations of MRI findings with ICP were calculated. Sensitivity and specificity of all methods were analyzed. ONSD and ONSD/ETD index at 3mm and 10mm behind the eyeball were significantly higher (p < 0.001) and OND/ONSD index at 3mm behind the eyeball was significantly lower (p < 0.001) in the IIH group. The ONSD/ETD index at 3mm had the highest area under the curve (AUC) value (0.898) with a cut-off of 0.27mm (82% sensitivity and 91.67% specificity) for predicting high cerebrospinal fluid (CSF) pressure, followed by ONSD measurements at 3mm (AUC = 0.886) with a cut-off of 6.17mm (83% sensitivity and 86.67% specificity). The OND/ONSD index at 3mm posterior to the eyeball decreased significantly as ICP increased, and the strength of the relationship was moderate (p < 0.001; r = -0.358). ONSD and ONSD/ETD index measured on MRI sequences are potentially useful in detecting elevated ICP. The OND/ONSD index correlates with CSF pressure and these techniques may be helpful in diagnosing IIH.

Optic nerve sheath measurement to monitor disease activity in giant cell arteritis: a pilot study

Introduction/ObjectivesOptic nerve sheath (ONS) enhancement using magnetic resonance imaging of the orbits was observed in patients with giant cell arteritis (GCA). We previously showed that ONS diameter (ONSD) by bedside ultrasound is increased in patient with active GCA. This study aims to assess whether ONSD decreases with clinical remission in patients with GCA.MethodsA prospective cohort study was conducted from June 2022 to January 2023. Patients who had an optic nerve ultrasound at GCA diagnosis as part of a previous crosssectional study were eligible. Optic nerve ultrasound was performed by the same investigator at diagnosis and month 3. ONSD (includes the optic nerve and its sheath) and optic nerve diameter (OND) were measured. Descriptive statistics for baseline characteristics and paired sample t-test were performed to assess the mean difference in OND and ONSD between diagnosis and month 3.ResultsNine patients with GCA were included. The median age at disease onset was 79 years (interquartile range (IQR) of 79–82 years), and 7 patients were males. All patients were in clinical remission at month 3 on prednisone (median dose of 15 mg/day, IQR of 10–25 mg). The mean ONSD was lower at month 3 (3.76 mm) compared to baseline (5.98 mm), with a paired mean difference of 2.22 mm (95% CI 1.41–3.03 mm, p < 0.001). As anticipated, OND measurements did not vary between diagnosis and month 3.ConclusionONSD on ultrasound improves after 3 months of therapy in patients with GCA. A longer prospective study is required to determine if ONSD is useful to assess disease activity in GCA.Key Points• ONS ultrasound can identify patients with active GCA.• The ONSD on ultrasound is dynamic and improved after 3 months of GCA therapy.• ONS ultrasound may be useful to monitor disease activity in GCA.

Automatic Optic Nerve Assessment From Transorbital Ultrasound Images: A Deep Learning-based Approach.

Transorbital Ultrasonography (TOS) is a promising imaging technology that can be used to characterize the structures of the optic nerve and the potential alterations that may occur in those structures as a result of an increase in intracranial pressure (ICP) or the presence of other disorders such as multiple sclerosis (MS) and hydrocephalus. In this paper, the primary objective is to develop a fully automated system that is capable of segmenting and calculating the diameters of structures that are associated with the optic nerve in TOS images. These structures include the optic nerve diameter sheath (ONSD) and the optic nerve diameter (OND). A fully convolutional neural network (FCN) model that has been pre-trained serves as the foundation for the segmentation method. The method that was developed was utilized to collect 464 different photographs from 110 different people, and it was accomplished with the assistance of four distinct pieces of apparatus. An examination was carried out to compare the outcomes of the automatic measurements with those of a manual operator. Both OND and ONSD have a typical inaccuracy of -0.12 0.32 mm and 0.14 0.58 mm, respectively, when compared to the operator. The Pearson correlation coefficient (PCC) for OND is 0.71, while the coefficient for ONSD is 0.64, showing that there is a positive link between the two measuring tools. A conclusion may be drawn that the technique that was developed is automatic, and the average error (AE) that was reached for the ONSD measurement is compatible with the ranges of inter-operator variability that have been discovered in the literature.

Optic Nerve Sheath Measurement on Ultrasound: A Novel Diagnostic Test for Giant Cell Arteritis.

Optic nerve sheath enhancement on magnetic resonance imaging has been reported in patients with giant cell arteritis (GCA), with or without visual manifestations. Whether similar findings can be documented on ultrasound is unknown. Optic nerve ultrasound is a point-of-care, easy to learn, rapid, and noninvasive technique. This study aims to investigate whether optic nerve sheath diameter (ONSD) measured on ultrasound is useful in the diagnosis of active, new-onset GCA. A single-center, diagnostic accuracy study was performed from June to November 2022 on consecutive eligible patients referred for suspected GCA. Optic nerve ultrasound was performed on both eyes. The ONSD (includes the optic nerve and its sheath) and optic nerve diameter (OND) were measured 3 mm behind the ocular globe. The presence or absence of GCA was confirmed clinically 6 months later. Multivariable linear regression, adjusting for age and sex, was used to determine the association between optic nerve ultrasound measures and final GCA diagnosis. Thirty participants were enrolled, including nine participants with a final diagnosis of GCA. Mean ± SD ONSD was 5.98 ± 1.17 mm in patients with GCA and 4.02 ± 0.99 mm in patients without GCA. Mean ONSD was greater by 1.26 mm in patients with GCA (95% confidence interval 0.30-2.21 mm, P = 0.01) compared with those without GCA, adjusting for age and sex. Mean ± SD OND was 2.97 ± 0.46 mm in patients with GCA and 2.47 ± 0.58 mm in patients without GCA. There was no evidence of an association between GCA diagnosis and OND. Patients with GCA had a significantly greater ONSD on ultrasound than patients without GCA. Optic nerve ultrasound may represent a novel, rapid, bedside diagnostic test for GCA. A large prospective study is required to confirm these findings and evaluate whether ONSD can be used as a disease activity biomarker in GCA.

Which compartments of the optic nerve and its sheath are associated with intracranial pressure? An exploratory study.

The optic nerve sheath diameter (ONSD) is a commonly used estimate of intracranial pressure (ICP). The rationale behind this is that pressure changes in the cerebrospinal fluid affect the optic nerve subarachnoid space (ONSAS) thickness. Still, possible effects on other compartments of the optic nerve sheath (ONS) have not been studied. This is the first study ever to analyze all measurable compartments of the ONS for associations with elevated ICP. We measured changes in ICP and changes in ONS compartments in 75 patients treated with invasive ICP monitoring at the Karolinska University Hospital. Associations between changes in ICP and changes in ONS compartments were estimated with generalized estimating equations. The potential to identify elevated ICP was assessed with the area under the receiver operating characteristic curve (AUROC) for ONS compartments associated with ICP changes. Both ONSAS and perioptic dura mater thickness were significantly associated with changes in ICP in multivariable modeling. ONSAS was the only compartment that independently predicted changes in ICP, with an AUROC of 0.69 for predicting ICP increase. Still, both the perioptic dura mater thickness and the optic nerve diameter added value in predicting ICP changes in multivariable modeling. The results from this study challenge the current understanding of the mechanism behind the association between ICP and ONSD. Contrary to the common opinion that ONSAS is the only affected compartment, this study shows a more complex picture. It suggests that all ONS compartments may add value in predicting changes in ICP.

Transorbital ultrasound in the diagnosis of giant cell arteritis.

The objective of this study was to prospectively evaluate the diagnostic efficacy of transorbital ultrasound (TOS) in patients newly diagnosed with giant cell arteritis (GCA), presenting with visual symptoms. Patients with newly diagnosed, untreated GCA were examined using TOS, assessing central retinal artery flow velocity [peak systolic velocity (PSV), end-diastolic velocity (EDV), resistance index (RI)], and optic nerve diameter (OND). Vascular ultrasound was conducted to evaluate the superficial temporal arteries, their branches, facial, axillary, carotid, and vertebral arteries. We enrolled 54 GCA patients, 27 with visual symptoms, and 27 healthy controls. Eyes of GCA patients with visual symptoms demonstrated significantly lower PSV and EDV (PSV: β = -1.91; P = 0.029; EDV: β = -0.57; P = 0.032) and significantly elevated OND (β = 0.79; P = 0.003) compared with controls. RI did not significantly differ from controls (β = -0.06, P = 0.129). Vascular ultrasound identified an average of 8.7 (SD ± 2.8) pathological vessels per GCA patient. A significant negative association was observed between the number of affected vessels and both PSV (P = 0.048) and EDV (P = 0.040). No association was found with RI (P = 0.249), while a positive significant association was noted with OND (P < 0.001). This study pioneers the application of TOS to assess structural eye changes in newly diagnosed, untreated GCA patients with visual symptoms. Our findings suggest reduced central retinal artery flow and increased optic nerve diameter as potential biomarkers for serious ocular involvement in GCA. The detected association between internal and external carotid artery involvement indicates a common pathophysiological mechanism underlying systemic and ocular manifestations of GCA.

The Effect of Hydrocephalus on the Optic Nerve in the Presence of Intracranial Mass

The measurement of optic nerve sheath diameter is a noninvasive, practical, and economical method used to identify increased intracranial pressure. The purpose of this study is to detect the preoperative and postoperative changes in optic nerve sheath diameter in patients with intracranial mass, to correlate these changes with optic nerve diameter variations, and to evaluate the impact of hydrocephalus on these alterations. This study was conducted with patients who presented to our clinic with complaints of intracranial mass, were decided for surgery, and underwent surgical procedures. The optic nerve and optic nerve sheath diameter measurement values were different preoperatively and postoperatively, with a significant decrease in the optic nerve sheath diameter in all groups in postoperative measurements, while the optic nerve diameter significantly increased. Although there was no significant difference between the effects of hydrocephalus and intracranial mass-related increase in intracranial pressure on the optic nerve and optic nerve sheath, it was observed that hydrocephalus increased intracranial pressure when considering the Evans ratio. It has been determined that as ventricular dilatation increases, so does intracranial pressure, which leads to an increase in the diameter of the optic nerve sheath, resulting in papilledema and thinning of the optic nerve. These findings indicate the importance of early cerebrospinal fluid diversion and monitoring optic nerve sheath diameter in the management.

Visual Impairment in Pre-Clinical Models of Mild Traumatic Brain Injury.

Impairment in visual function is common after traumatic brain injury (TBI) in the clinical setting, a phenomenon that translates to pre-clinical animal models as well. In Morris et al. (2021), we reported histological changes following weight-drop-induced TBI in a rodent model including retinal ganglion cell (RGC) loss, decreased electroretinogram (ERG) evoked potential, optic nerve diameter reduction, induced inflammation and gliosis, and loss of myelin accompanied by markedly impaired visual acuity. In this review, we will describe several pre-clinical TBI models that result in injuries to the visual system, indicating that visual function may be impaired following brain injury induced by a number of different injury modalities. This underscores the importance of understanding the role of the visual system and the potential detrimental sequelae to this sensory modality post-TBI. Given that most commonly employed behavioral tests such as the Elevated Plus Maze and Morris Water Maze rely on an intact visual system, interpretation of functional deficits in diffuse models may be confounded by off- target effects on the visual system.

Prospective analysis of optic nerve diameter and NSE values in patients with refractory headaches

Purpose: This study aims to investigate the usability of ultrasonographic optic nerve diameter measurement and plasma neuron-specific enolase (NSE) levels in detecting secondary causes of headaches in patients with refractory headaches in emergency department.&#x0D; Materials and Methods: The study was conducted in a university-based adult emergency department over 3 years. Sixty-six consecutive patients presenting to the emergency department with refractory headaches and 50 healthy volunteers for the control group were included. Information recorded included the duration of complaints, type and location of headache, symptoms, co-morbidities, results of imaging studies, optic nerve diameters, results of lactate, arterial blood gas and NSE levels.&#x0D; Results: A total of 66 patients were included, comprising 33 females. The mean age was 43.05 ± 17.06 years. Secondary causes of headache were identified in 45 patients (68.2%). Evaluation of ultrasonographic optic nerve diameter revealed that 17 (25.8%) right and 21 (31.8%) left optic nerve diameters were ≥5 mm. Optic nerve diameter values were significantly higher in patients diagnosed with secondary headache compared to those with primary headache, with no statistically significant difference observed in NSE values. Lactate levels in patients with secondary headaches were significantly higher than those in patients with primary headaches.&#x0D; Conclusion: In patients admitted to the emergency department with refractory headaches and normal imaging, ultrasonographic optic nerve diameter measurement may be preferred as an easily accessible method to guide the detection of secondary causes. NSE was not an effective in the early selection of patients with secondary headaches.

Synergistic Protection of Retinal Ganglion Cells (RGCs) by SARM1 Inactivation with CNTF in a Rodent Model of Nonarteritic Anterior Ischemic Optic Neuropathy.

We evaluated whether inhibiting sterile alpha and (Toll/interleukin receptor (TIR)) motif-containing 1 (SARM1) activity protects retinal ganglion cells (RGCs) following ischemic axonopathy (rodent nonarteritic anterior ischemic optic neuropathy: rNAION) by itself and combined with ciliary neurotrophic factor (CNTF). Genetically modified SARM1(-) rats were rNAION-induced in one eye and compared against equivalently induced wild-type animals of the same background. Optic nerve (ON) diameters were quantified using optical coherence tomography (SD-OCT). RGCs were quantified 30 d post-induction using retinal stereology for Brn3a(+) nuclei. ON sections were analyzed by TEM and immunohistochemistry. SARM1(-)(-) and WT animals were then bilaterally sequentially rNAION-induced. One eye received intravitreal vehicle injection following induction; the contralateral side received CNTF and was analyzed 30 d post-induction. Inhibiting SARM1 activity suppressed axonal collapse following ischemic axonopathy. SARM1(-) animals significantly reduced RGC loss, compared with WT animals (49.4 ± 6.8% RGC loss in SARM1(-) vs. 63.6 ± 3.2% sem RGC loss in WT; Mann-Whitney one-tailed U-test, (p = 0.049)). IVT-CNTF treatment vs. IVT-vehicle in SARM1(-) animals further reduced RGC loss by 24% at 30 d post-induction, but CNTF did not, by itself, improve long-term RGC survival in WT animals compared with vehicle (Mann-Whitney one-tailed t-test; p = 0.033). While inhibiting SARM1 activity is itself neuroprotective, combining SARM1 inhibition and CNTF treatment generated a long-term, synergistic neuroprotective effect in ischemic neuropathy. Combinatorial treatments for NAION utilizing independent neuroprotective mechanisms may thus provide a greater effect than individual treatment modalities.

Establishing Optic Nerve Diameter Threshold Sensitive and Specific for Optic Atrophy Diagnosis.

To determine apotential threshold optic nerve diameter (OND) that could reliably differentiate healthy nerves from those affected by optic atrophy (OA) and to determine correlations of OND in OA with retinal nerve fiber layer (RNFL) thickness, visual acuity (VA), and visual field mean deviation (VFMD). This was aretrospective case control study. Magnetic resonance (MR) images were reviewed from individuals with OA aged 18years or older with vision loss for more than 6months and an OA diagnosis established by aneuro-ophthalmologist. Individuals without OA who underwent MR imaging of the orbit for other purposes were also collected. OND was measured on coronal T2-weighted images in the midorbital section, 1cm posterior to the optic disc. Measurements of mean RNFL thickness, VA and VFMD were also collected. In this study 47 OA subjects (63% women, 78eyes) and 75 normal subjects (42.7% women, 127 eyes) were assessed. Healthy ONDs (mean 2.73 ± 0.24 mm) were significantly greater than OA nerve diameters (mean 1.94 ± 0.32 mm; P < 0.001). Athreshold OND of ≤2.3 mmhadasensitivity of 0.92 and aspecificity of 0.93 in predicting OA. Mean RNFL (r = 0.05, p = 0.68), VA (r = 0.17, p = 0.14), and VFMD (r = 0.18, p = 0.16) were not significantly associated with OND. ONDs are significantly reduced in patients with OA compared with healthy nerves. Athreshold OND of ≤2.3 mm is highly sensitive and specific for adiagnosis of OA. OND was not significantly correlated with RNFL thickness, VA, or VFMD.

Echographic Optic Nerve Evaluation: A Novel Diagnostic Modality in Glaucoma

Introduction: Primary Open-Angle Glaucoma (POAG) is considered a leading cause of blindness among all others. Different technologies such as Scanning Laser Polarimetry (SLP) and Optical Coherence Tomography (OCT) closely correlate in measuring structural parameters of the Retinal Nerve Fiber Layer (RNFL) and Optic Nerve Head (ONH). Visual impairment related to glaucomatous damage is attributed to the RNFL. Earlier studies have shown that retro-bulbar optic nerve thickness is reduced in glaucoma and have suggested that this is also the result of RNFL destruction. Aim: To investigate the correlation between the orbital and intraocular portions of the optic nerve among POAG patients. Materials and Methods: This was a hospital-based crosssectional study done in a tertiary care ophthalmic institute from October 2019 to February 2021. One eye of 32 volunteers with newly diagnosed POAG underwent optic disc analysis using OCT and echographic measurements of the retrobulbar optic nerve. For statistical calculations, Statistical Package for Social Sciences (SPSS) Statistics version 20.0 software (IBM Corp., Armonk, NY, USA) was used. Spearman’s rho (rs) was used as the index of correlation between retrobulbar optic nerve dimensions and ONH topographical data. A correlation between OCT-based RNFL and optic disc parameters was compared with retrobulbar optic nerve dimensions measured with the help of Ultrasonography- Brightness (USG B) Scan. Results: Orbital Optic Nerve Diameter (OND) and Optic Nerve Cross-sectional Area (ONCSA) significantly and positively correlated with Neuro-retinal Rim (NR) area (OND: p-value=0.00001; ONCSA: p-value=0.00001) and average nerve fiber layer thickness (OND: p-value=0.0001; ONCSA: p-value=0.00002). The Retrobulbar ONCSA-to-disc area ratio (ONCSA/D) was found to have a statistically demonstrable positive correlation with Neuro-retinal Rim Area/Disc area ratio (NR/D) (p=0.00003). Conclusion: This study showed that retrobulbar optic nerve dimensions correlate well with SD-OCT-based ONH parameters. Echographic measurements of the retrobulbar optic nerve add a new biomarker in the diagnosis of glaucoma.

A comparative analysis of biometric parameters of optic nerves obtained by ultrasonic sensors of varied frequencies

Purpose: a comparative analysis of biometric parameters of the optic nerve obtained by different diagnostic ultrasound sensors.Material and methods. We examined 20 healthy volunteers with emmetropia aged 20 to 40 years (40 eyes), average age 30.5 ± 5.4 years, who had no complaints or ophthalmic pathologies. Ultrasound scanning was performed on a multifunctional Voluson E8 (GE) scanner (11–18 MHz linear sensor), ophthalmic ultrasound device Ellex Eyecubed (a conventional 10 MHz transducer) and an ophthalmic scanner Absolu «Quantel Medical» (a 20 MHz transducer). All examinations were carried out by one operator who used the same scanning technique and measured the optic nerve sheath diameter (ONSD) and optic nerve diameter (OND) without sheaths in both eyes. Six consequent measurements of the ONSD and the OND parameters were performed to ascertain the reproducibility of the examinations and evaluate the variation coefficient.Results. The analysis revealed no statistically significant differences in the ONSD and in the OND obtained with 11–18 MHz, 10 MHz and 20 MHz transducers in the B-mode (р &gt; 0.05). The minimum variation coefficient of the optic nerve thickness parameters was registered using a high-frequency 20 MHz transducer on the ophthalmic scanner. The biometry obtained with a high frequency 20 MHz transducer could be considered as the most reproducible.Conclusion. A high frequency 20 MHz transducer can be recommended for optimal visualization and precise evaluation of biometric parameters of the retrobulbar part of the optic nerve. Transducers of multifunctional scanners with the frequency range from 11 to 20 MHz can be used for measurements of the optic nerve sheath diameter.

Smaller optic nerve diameters and reduced flow velocity of ophthalmic artery suggest a history of optic neuritides: Transorbital Ultrasonography and Doppler Ultrasound in multiple sclerosis

Smaller optic nerve diameters and reduced flow velocity of ophthalmic artery suggest a history of optic neuritides: Transorbital Ultrasonography and Doppler Ultrasound in multiple sclerosis

Predicting optic atrophy in patients with anterior uveitis by computed tomography-based assessment of optic nerve diameter

Background: An objective assessment of factors for ocular inflammation and its sequelae and diagnostic assessment of possible development of the sequelae in early phases of uveitis are essential for early and effective treatment of endogenous uveitis. Purpose: To determine whether it is possible to predict optic atrophy in patients with anterior uveitis using computed tomography (CT)-based assessment of optic nerve diameter. Material and Methods: Patients with anterior uveitis underwent a routine eye examination (ophthalmoscopy, biomicroscopy, intraocular pressure (IOP) measurement, and Humphrey perimetry). In addition, they underwent CT-based assessment of optic disc diameter at 3-5 mm from the entrance into the orbit in the affected eye and the contralateral healthy eye. Patients received treatment as per the protocol. Results: The percentage difference in optic nerve diameter between patients with uveitis complicated by optic neuritis and those with uveitis only for affected eyes was large (33.1%) and statistically significant. At 3 months and 6 months after initiation of treatment, mean optic disc diameter in patients with optic neuritis decreased by 37.2% and 49.1%, respectively, compared to baseline values. At 6 months, a decrease in optic nerve diameter among optic neuritis patients was observed both in those who received treatment and in those who failed to receive treatment, but was less marked in the former patients. Particularly, from 3 months to 6 months, optic nerve diameter decreased by 17.3% in treated optic neuritis patients versus 23.5% in those who remained untreated. Conclusion: CT-based data on the change in the optic nerve diameter at the entrance into the orbit in patients with optic neuritis is an objective characteristic of the presence and grade of atrophic process. Early identification of the potential for development of optic atrophy in individuals with optic neuritis will make it possible to treat them early and, consequently, to prevent or stabilize the process.

Development of a Deep Learning–Based System for Optic Nerve Characterization in Transorbital Ultrasound Images on a Multicenter Data Set

Objective Characterization of the optic nerve through measurement of optic nerve diameter (OND) and optic nerve sheath diameter (ONSD) using transorbital sonography (TOS) has proven to be a useful tool for the evaluation of intracranial pressure (ICP) and multiple neurological conditions. We describe a deep learning–based system for automatic characterization of the optic nerve from B-mode TOS images by automatic measurement of the OND and ONSD. In addition, we determine how the signal-to-noise ratio in two different areas of the image influences system performance. Methods A UNet was trained as the segmentation model. The training was performed on a multidevice, multicenter data set of 464 TOS images from 110 subjects. Fivefold cross-validation was performed, and the training process was repeated eight times. The final prediction was made as an ensemble of the predictions of the eight single models. Automatic OND and ONSD measurements were compared with the manual measurements taken by an expert with a graphical user interface that mimics a clinical setting. Results A Dice score of 0.719 ± 0.139 was obtained on the whole data set merging the test folds. Pearson's correlation was 0.69 for both OND and ONSD parameters. The signal-to-noise ratio was found to influence segmentation performance, but no clear correlation with diameter measurement performance was determined. Conclusion The developed system has a good correlation with manual measurements, proving that it is feasible to create a model capable of automatically analyzing TOS images from multiple devices. The promising results encourage further definition of a standard protocol for the automatization of the OND and ONSD measurement process using deep learning–based methods. The image data and the manual measurements used in this work will be available at 10.17632/kw8gvp8m8x.1. Characterization of the optic nerve through measurement of optic nerve diameter (OND) and optic nerve sheath diameter (ONSD) using transorbital sonography (TOS) has proven to be a useful tool for the evaluation of intracranial pressure (ICP) and multiple neurological conditions. We describe a deep learning–based system for automatic characterization of the optic nerve from B-mode TOS images by automatic measurement of the OND and ONSD. In addition, we determine how the signal-to-noise ratio in two different areas of the image influences system performance. A UNet was trained as the segmentation model. The training was performed on a multidevice, multicenter data set of 464 TOS images from 110 subjects. Fivefold cross-validation was performed, and the training process was repeated eight times. The final prediction was made as an ensemble of the predictions of the eight single models. Automatic OND and ONSD measurements were compared with the manual measurements taken by an expert with a graphical user interface that mimics a clinical setting. A Dice score of 0.719 ± 0.139 was obtained on the whole data set merging the test folds. Pearson's correlation was 0.69 for both OND and ONSD parameters. The signal-to-noise ratio was found to influence segmentation performance, but no clear correlation with diameter measurement performance was determined. The developed system has a good correlation with manual measurements, proving that it is feasible to create a model capable of automatically analyzing TOS images from multiple devices. The promising results encourage further definition of a standard protocol for the automatization of the OND and ONSD measurement process using deep learning–based methods. The image data and the manual measurements used in this work will be available at 10.17632/kw8gvp8m8x.1.

Evaluation of optic nerve sheath complex by magnetic resonance imaging in patients with idiopathic normal pressure hydrocephalus

Background: We aimed to evaluate the optic nerve and optic nerve sheath diameter of patients with idiopathic normal pressure hydrocephalus with magnetic resonance imaging and to compare with the normal population. Methods: Magnetic resonance images and clinical records of the patients were retrospectively evaluated between 01.01.2015 and 01.01.2020. Twenty one patients in the normal pressure hydrocephalus group and 47 patients in the control group were included. Measurements were performed from the images obtained by creating multiplanar reconstructions from thin-slice Fast Spin Echo T2-weighted images. Measurements were made of optic nerve from the 3 mm posterior to the optic globe, on the plane which is oriented perpendicular to the nerve. Results: There was no difference between the two groups in terms of optic nerve diameters. Optic nerve sheath diameters are significantly higher in the normal pressure hydrocephalus group (p&lt;0.0001). Conclusion: Morphological analysis of the optic nerve sheath complex which contains cerebrospinal fluid will contribute to the diagnosis and understanding chronic effects of normal pressure hydrocephalus, a disease in which changes in brain compliance and cerebrospinal fluid absorption are suspected in its etiology.

Pediatric optic nerve and globe measurements on magnetic resonance imaging: establishing norms for children.

Normal optic nerve diameter (OND) and optic nerve sheath diameter (ONSD) may be beneficial for describing optic nerve pathway abnormality reflecting increased intracranial pressure. Nonetheless, magnetic resonance imaging (MRI) measurement of the normal ONSD range and its associations with clinical factors and eyeball transverse diameter (ETD) are not well established in children. To establish normal OND, ONSD, ETD, and OND/ONSD and ONSD/ETD measurements in children and their associations with age and sex. We evaluated and analyzed 336 brain MRI studies of children aged 0.5 months to 18 years. We measured a total of 672 optic nerves. The OND and ONSD were measured 1 cm anterior to the optic foramina and 3 mm behind the optic disc on an axial T2 sequence. The mean OND 3 mm and 1 cm, ONSD 3 mm and 1 cm, and ETD were 0.23 ± 0.05 mm and 0.16 ± 0.04 mm, 0.53 ± 0.08 mm and 0.38 ± 0.06 mm, and 2.3 ± 0.13, respectively. Only ONSD 1 cm was independent of age (P = 0.247). ONSD 3 mm and ETD were significantly wider in boys compared to girls and significantly influenced by age (both P < 0.001). Age at scan and ETD were significantly correlated (P < 0.001). We established MRI-based OND, ONSD, ETD, and ONSD/ETD and OND/ONSD ratio normative values in children, which can be helpful in pediatric populations with disease.

Measurement of Optic Nerve Sheath Diameter by Computed Tomography in the Pediatric Population: Normal Values.

To determine the normal values of optic nerve sheath diameter (ONSD) by computed tomography (CT) in the pediatric population. The CT scans of pediatric patients aged 1 to 16 years who underwent brain CT for different reasons, who did not have intracranial pathology or increased intracranial pressure, and who had no pathology on CT were included in the study. Four age groups were defined with the following ranges: 1 to 2, 3 to 6, 7 to 10, and 11 to 16 years. ONSD was measured from axial CT images, 3 and 10 mm behind the optic globe. The normative values of ONSD measured on CT imaging in children aged 1 to 16 years were reported. The change in ONSD according to age was investigated. ONSD was found to increase with age at both levels measured. The difference was statistically significant. Normal values should be known to detect pathologies that may cause an increase in optic nerve diameter. The values reported in this study can serve as a reference for normal optic nerve sheath diameter in the pediatric age group. [J Pediatr Ophthalmol Strabismus. 2024;61(1):38-43.].

Effect of General Anesthesia on MR Optic Nerve Sheath Diameter in the Pediatric Population.

Papilledema is thought to be the hallmark sign of increased intracranial pressure (ICP). Distension of the subarachnoid space within the optic nerve sheath is also commonly reported in MR studies as an indirect sign of increased ICP. General anesthesia and positive pressure ventilation might result in changes in optic sheath diameter (OSD) observed on clinical brain MRI. Retrospective. One hundred forty-five patients (154 MRI scans, 7.3 years ± 5.1); 97 studies in the anesthesia group (4.4 years ± 3.4) of which 22 had papilledema, and 57 in the non-anesthesia group (12.3 years ± 3.2), of which 28 had papilledema. 1.5T or 3.0T volumetric T2 images. T2 images were obtained from different vendors. OSD, optic nerve diameter (OND), and peri-optic cerebrospinal fluid (CSF) were measured manually on T2-weighted MR images for various population subgroups (with and without anesthesia; with or without papilledema). The correlation between these measurements and the clinical diagnosis of papilledema was evaluated via receiver operating characteristic (ROC) analysis. Chi-square test; Mann-Whitney Test; Spearman's test and ROCs; Interclass correlation coefficient, P = 0.05. General anesthesia resulted in significantly larger mean OSD in patients with or without papilledema (7.3 ± 1.0 mm vs. 6.1 ± 1.1 mm and 6.7 ± 1.0 mm vs. 5.4 ± 0.9 mm, respectively). In the non-anesthesia group, the average OSD values (6.1 ± 1.1 mm) were significantly higher in papilledema patients compared to non-papilledema patients (5.4 ± 0.9 mm), with larger peri-optic CSF rim (1.6 ± 0.4 mm vs. 1.3 ± 0.3 mm). In the anesthesia group, OND was significantly larger in papilledema patients (3.4 ± 0.4 mm vs. 3.1 ± 0.5 mm), though the average peri-optic CSF rim did not reach a significance in papilledema compared with non-papilledema patients (2.0 ± 0.3 mm vs. 1.8 ± 0.4 mm, P = 0.06). In patients with general anesthesia, peri-optic CSF rim had a limited correlation with increased ICP. In the pediatric population, imaging findings of increased OSD on brain MRI might be related to general anesthesia rather than increased ICP. The interpretation of optic nerve sheath distention should be reported cautiously in conjunction with anesthesia status, especially in the pediatric population. 4 Technical Efficacy: 5.