Cerebrospinal fluid dynamics along the optic nerve

Heart-on-a-chip systems with tissue-specific functionalities for physiological, pathological, and pharmacological studies

Recent advances in heart-on-a-chip systems hold great promise to facilitate cardiac physiological, pathological, and pharmacological studies. This review focuses on the development of heart-on-a-chip systems with tissue-specific functionalities. For one thing, the strategies for developing cardiac microtissues on heart-on-a-chip systems that closely mimic the structures and behaviors of the native heart are analyzed, including the imitation of cardiac structural and functional characteristics. For another, the development of techniques for real-time monitoring of biophysical and biochemical signals from cardiac microtissues on heart-on-a-chip systems is introduced, incorporating cardiac electrophysiological signals, contractile activity, and biomarkers. Furthermore, the applications of heart-on-a-chip systems in intelligent cardiac studies are discussed regarding physiological/pathological research and pharmacological assessment. Finally, the future development of heart-on-a-chip toward a higher level of systematization, integration, and maturation is proposed.

Automatic segmentation and quantification of the optic nerve on MRI using a 3D U-Net

Purpose

Pathological conditions associated with the optic nerve (ON) can cause structural changes in the nerve. Quantifying these changes could provide further understanding of disease mechanisms. We aim to develop a framework that automatically segments the ON separately from its surrounding cerebrospinal fluid (CSF) on magnetic resonance imaging (MRI) and quantifies the diameter and cross-sectional area along the entire length of the nerve.

Approach

Multicenter data were obtained from retinoblastoma referral centers, providing a heterogeneous dataset of 40 high-resolution 3D T2-weighted MRI scans with manual ground truth delineations of both ONs. A 3D U-Net was used for ON segmentation, and performance was assessed in a tenfold cross-validation (n = 32 ) and on a separate test-set (n = 8 ) by measuring spatial, volumetric, and distance agreement with manual ground truths. Segmentations were used to quantify diameter and cross-sectional area along the length of the ON, using centerline extraction of tubular 3D surface models. Absolute agreement between automated and manual measurements was assessed by the intraclass correlation coefficient (ICC).

Results

The segmentation network achieved high performance, with a mean Dice similarity coefficient score of 0.84, median Hausdorff distance of 0.64 mm, and ICC of 0.95 on the test-set. The quantification method obtained acceptable correspondence to manual reference measurements with mean ICC values of 0.76 for the diameter and 0.71 for the cross-sectional area. Compared with other methods, our method precisely identifies the ON from surrounding CSF and accurately estimates its diameter along the nerve's centerline.

Conclusions

Our automated framework provides an objective method for ON assessment in vivo.

Perioptic cerebro-spinal fluid transudation: case report of an unusual finding of optic hydrops in idiopathic intracranial hypertension

Background

Idiopathic intracranial hypertension (IIH) has well-described imaging findings, typically reversible with the adequate treatment. We hereby report a case of IIH with a peculiar imaging finding, that to our knowledge and by the research conducted, has never been described before—cerebro-spinal fluid (CSF) transudation across the optic nerve sheath.

Case presentation

A 15-year-old girl with a 2-week history of occipital headache, nausea and vomiting, diplopia, blurred vision and tinnitus in her right ear, was admitted in the neuropediatric department and after extensive diagnostic work-up was diagnosed with IIH. The MRI showed typical signs of idiopathic intracranial hypertension, including enlargement of the perioptic CSF spaces associated with a peculiar finding described as a blurred hyperintensity T2/FLAIR of the perioptic fat, which was likely related to transudation of CSF. The adequate medical therapy (including corticosteroids and acetazolamide) for 2 weeks didn’t revert the signs and symptoms and so a lumboperitoneal shunt was placed with complete resolution of the clinical picture and the imaging findings described.

Conclusions

The documentation of CSF transudation around the optic nerve in the setting of hydrops has never been reported before and should be recognized by the neuroradiologist. It seems to be reversible, like the other findings of IIH and its physiopathology is not clear.