Cerebrospinal fluid velocity changes of idiopathic scoliosis: a preliminary study on 3-T PC-MRI and 3D-SPACE-VFAM data

Decoding pulsatile patterns of cerebrospinal fluid dynamics through enhancing interpretability in machine learning

Analyses of complex behaviors of Cerebrospinal Fluid (CSF) have become increasingly important in diseases diagnosis. The changes of the phase-contrast magnetic resonance imaging (PC-MRI) signal formed by the velocity of flowing CSF are represented as a set of velocity-encoded images or maps, which can be thought of as signal data in the context of medical imaging, enabling the evaluation of pulsatile patterns throughout a cardiac cycle. However, automatic segmentation of the CSF region in a PC-MRI image is challenging, and implementing an explained ML method using pulsatile data as a feature remains unexplored. This paper presents lightweight machine learning (ML) algorithms to perform CSF lumen segmentation in spinal, utilizing sets of velocity-encoded images or maps as a feature. The Dataset contains 57 PC-MRI slabs by 3T MRI scanner from control and idiopathic scoliosis participants are involved to collect data. The ML models are trained with 2176 time series images. Different cardiac periods image (frame) numbers of PC-MRIs are interpolated in the preprocessing step to align to features of equal size. The fivefold cross-validation procedure is used to estimate the success of the ML models. Additionally, the study focusses on enhancing the interpretability of the highest-accuracy eXtreme gradient boosting (XGB) model by applying the shapley additive explanations (SHAP) technique. The XGB algorithm presented its highest accuracy, with an average fivefold accuracy of 0.99% precision, 0.95% recall, and 0.97% F1 score. We evaluated the significance of each pulsatile feature's contribution to predictions, offering a more profound understanding of the model's behavior in distinguishing CSF lumen pixels with SHAP. Introducing a novel approach in the field, develop ML models offer comprehension into feature extraction and selection from PC-MRI pulsatile data. Moreover, the explained ML model offers novel and valuable insights to domain experts, contributing to an enhanced scholarly understanding of CSF dynamics.

The significance of cerebrospinal fluid dynamics in adolescent idiopathic scoliosis using time-SLIP MRI

Adolescent idiopathic scoliosis (AIS) affects approximately 3% of the global population. Recent studies have drawn attention to abnormalities in the dynamics of the CSF as potential contributors. This research aims to employ the Time-Spatial Labeling Inversion Pulse (Time-SLIP) MRI to assess and analyze cerebrospinal fluid (CSF) dynamics in AIS patients. 101 AIS patients underwent Time-SLIP MRI. Images were taken at the mid-cervical and craniocervical junction regions. The sum of the maximum movement distances of CSF on the ventral and dorsal sides of the spinal canal within a single timeframe was defined and measured as Travel Distance (TD). Correlations between TD, age, Cobb angle, and Risser grade were analyzed. TD comparisons were made across Lenke classifications. TD for all patients was a weak correlation with the Cobb angle (r = - 0.16). Comparing TD between Lenke type 1 and 5, type 5 patients display significantly shorter TD (p < 0.05). In Risser5 patients with Lenke type 5 showed a significant negative correlation between Cobb angle and TD (r = - 0.44). Lenke type 5 patients had significantly shorter CSF TD compared to type1, correlating with worsening Cobb angles. Further analysis and exploration are required to understand the mechanism of onset and progression.

Characterising spinal cerebrospinal fluid flow in the pig with phase-contrast magnetic resonance imaging

BACKGROUND

Detecting changes in pulsatile cerebrospinal fluid (CSF) flow may assist clinical management decisions, but spinal CSF flow is relatively understudied. Traumatic spinal cord injuries (SCI) often cause spinal cord swelling and subarachnoid space (SAS) obstruction, potentially causing pulsatile CSF flow changes. Pigs are emerging as a favoured large animal SCI model; therefore, the aim of this study was to characterise CSF flow along the healthy pig spine.

METHODS

Phase-contrast magnetic resonance images (PC-MRI), retrospectively cardiac gated, were acquired for fourteen laterally recumbent, anaesthetised and ventilated, female domestic pigs (22-29 kg). Axial images were obtained at C2/C3, T8/T9, T11/T12 and L1/L2. Dorsal and ventral SAS regions of interest (ROI) were manually segmented. CSF flow and velocity were determined throughout a cardiac cycle. Linear mixed-effects models, with post-hoc comparisons, were used to identify differences in peak systolic/diastolic flow, and maximum velocity (cranial/caudal), across spinal levels and dorsal/ventral SAS. Velocity wave speed from C2/C3 to L1/L2 was calculated.

RESULTS

PC-MRI data were obtained for 11/14 animals. Pulsatile CSF flow was observed at all spinal levels. Peak systolic flow was greater at C2/C3 (dorsal: - 0.32 ± 0.14 mL/s, ventral: - 0.15 ± 0.13 mL/s) than T8/T9 dorsally (- 0.04 ± 0.03 mL/s; p < 0.001), but not different ventrally (- 0.08 ± 0.08 mL/s; p = 0.275), and no difference between thoracolumbar levels (p > 0.05). Peak diastolic flow was greater at C2/C3 (0.29 ± 0.08 mL/s) compared to T8/T9 (0.03 ± 0.03 mL/s, p < 0.001) dorsally, but not different ventrally (p = 1.000). Cranial and caudal maximum velocity at C2/C3 were greater than thoracolumbar levels dorsally (p < 0.001), and T8/T9 and L1/L2 ventrally (p = 0.022). Diastolic velocity wave speed was 1.41 ± 0.39 m/s dorsally and 1.22 ± 0.21 m/s ventrally, and systolic velocity wave speed was 1.02 ± 0.25 m/s dorsally and 0.91 ± 0.22 m/s ventrally.

CONCLUSIONS

In anaesthetised and ventilated domestic pigs, spinal CSF has lower pulsatile flow and slower velocity wave propagation, compared to humans. This study provides baseline CSF flow at spinal levels relevant for future SCI research in this animal model.

The use of MRI in the study of patients with idiopathic scoliosis: a systematic review of the literature

Objective. To analyze the frequency of hidden neuraxial pathology in idiopathic scoliosis (IS), to substantiate the need for MRI in IS and to identify promising areas for the use of MRI in the examination of patients with IS.Material and Methods. The literature review was carried out using the PubMed and Google Scholar databases. Of the 780 papers on the research topic, 65 were selected after removing duplicates and checking for inclusion/exclusion criteria. As a result, 49 original studies were included in the analysis. Level of evidence – II.Results. According to modern literature, the main direction of using MRI in idiopathic scoliosis is the search for predictors of latent pathology of the spinal cord and craniovertebral junction. The frequency of neuraxial pathology in idiopathic scoliosis is 8 % for adolescent IS and 16 % for early IS. The main predictors of neuraxial pathology are male sex, early age of deformity onset, left-sided thoracic curve and thoracic hyperkyphosis. MRI in IS may be a useful addition to radiological diagnostic methods to identify risk factors and to study degenerative changes in the spine.Conclusion. MRI of the spine should be performed in the early stages of IS to detect latent spinal cord tethering. In type I Chiari anomalies, there is a possibility that early neurosurgery can prevent the development of scoliosis. The main signs of latent neuraxial pathology in IS are early progression of spinal deformity, left-sided thoracic curve, male gender and thoracic kyphosis over 40° according to Cobb.MRI can be used as an effective non-invasive tool in research aimed at identifying risk factors for IS, including helping to track early degeneration of intervertebral discs.

Venous Segmental Flow Changes after Superficial Venous Intervention Demonstrating by Quantitative Phase-Contrast Magnetic Resonance Analysis: Preliminary Data from a Longitudinal Cohort Study

The effects of superficial venous intervention on hemodynamics can be quantified using two-dimensional phase-contrast magnetic resonance imaging (2D PC-MRI). Twelve patients received pre- and postintervention 2D PC-MRI analysis using quantitative hemodynamic parameters. Fifteen healthy volunteers served as controls. The 2D PC-MRI results of the target limbs (limbs scheduled for intervention for venous reflux) differed from those of the controls in terms of stroke volume (SV), forward flow volume (FFV), absolute stroke volume (ASV), and mean flux (MF) in all venous segments. The velocity time integral (VTI) and mean velocity (MV) of the popliteal vein (PV) segments were similar between the target limbs and controls preoperatively. After intervention, the target limbs exhibited an increase in VTI and MV in the femoral vein (FV) and PV segments. We compared the target and nontreated limbs of the individual patients preoperatively and postoperatively to minimalize individual bias. All QFlow parameter ratios in the FV segment increased after venous intervention (VTI, p = 0.025; MV, p = 0.024). In the PV segment, FFV and ASV increased significantly (p = 0.035 and 0.024, respectively). After interventions, the volume (FFV and ASV) of the PV segment and the efficiency (VTI and MV) of the FV segment significantly increased.

Turning the Curve Into Straight: Phenogenetics of the Spine Morphology and Coordinate Maintenance in the Zebrafish

The vertebral column, or spine, provides mechanical support and determines body axis posture and motion. The most common malformation altering spine morphology and function is adolescent idiopathic scoliosis (AIS), a three-dimensional spinal deformity that affects approximately 4% of the population worldwide. Due to AIS genetic heterogenicity and the lack of suitable animal models for its study, the etiology of this condition remains unclear, thus limiting treatment options. We here review current advances in zebrafish phenogenetics concerning AIS-like models and highlight the recently discovered biological processes leading to spine malformations. First, we focus on gene functions and phenotypes controlling critical aspects of postembryonic aspects that prime in spine architecture development and straightening. Second, we summarize how primary cilia assembly and biomechanical stimulus transduction, cerebrospinal fluid components and flow driven by motile cilia have been implicated in the pathogenesis of AIS-like phenotypes. Third, we highlight the inflammatory responses associated with scoliosis. We finally discuss recent innovations and methodologies for morphometrically characterize and analyze the zebrafish spine. Ongoing phenotyping projects are expected to identify novel and unprecedented postembryonic gene functions controlling spine morphology and mutant models of AIS. Importantly, imaging and gene editing technologies are allowing deep phenotyping studies in the zebrafish, opening new experimental paradigms in the morphometric and three-dimensional assessment of spinal malformations. In the future, fully elucidating the phenogenetic underpinnings of AIS etiology in zebrafish and humans will undoubtedly lead to innovative pharmacological treatments against spinal deformities.