Hypoxic-Ischemic brain injury in an adult: Magnetic Resonance Imaging findings

MRI Findings of Acute Hippocampal Disorders: Pictorial Essay

The hippocampus is one of the most metabolically active regions of the brain; therefore, it may be affected by various acute disorders. This study aimed to introduce and categorize various acute conditions that can involve the hippocampus and explain the findings of MRI, especially diffusion-weighted imaging (DWI). Acute hippocampal disorders are divided into six categories: infection, inflammation, metabolic, ischemic, traumatic, and miscellaneous. In this study, patients were retrospectively reviewed based on clinical findings and MRI, especially DWI. All diseases had been confirmed clinically or pathologically. Many acute hippocampal disorders overlap with the clinical manifestations. Thus, it is necessary to categorize acute hippocampal lesions and understand their specific imaging findings for differential diagnosis.

Role of Neonatal Behavioral Neurological Assessment combined with magnetic resonance diffusion tensor imaging in evaluating white matter development in preterm infants

OBJECTIVES

To study the correlation of fractional anisotropy (FA) on magnetic resonance diffusion tensor imaging with Neonatal Behavioral Neurological Assessment (NBNA) score in preterm infants, and to study the role of FA in evaluating white matter development from the perspective of imaging.

METHODS

A prospective study was performed for 98 preterm infants who were admitted to the Neonatal Intensive Care Unit of the Third Affiliated Hospital of Zhengzhou University within 24 hours after birth from October 2016 to January 2020. According to the results of NBNA, they were divided into an abnormal group with 51 infants (NBNA score <37) and a normal group with 47 infants (NBNA score ≥37). The FA values of 10 regions of interest were collected and compared between the two groups. The correlations of FA value and umbilical arterial blood gas pH value with the NBNA score were analyzed.

RESULTS

Compared with the normal group, the abnormal group had significantly lower FA value of the posterior limb of the internal capsule and umbilical arterial blood pH (P<0.05). The FA value of the posterior limb of the internal capsule and umbilical arterial blood pH were positively correlated with the NBNA score (r=0.584 and 0.604 respectively, P<0.001), and the FA value of the posterior limb of the internal capsule was positively correlated with umbilical arterial blood pH (r=0.426, P<0.05).

CONCLUSIONS

The FA value of the posterior limb of the internal capsule can quantitatively reflect white matter development in preterm infants and is correlated with the NBNA score. The combination of the two indices can help to evaluate white matter development in preterm infants more accurately and objectively. Citation.

Gyriform restricted diffusion in adults: looking beyond thrombo-occlusions

Gyriform restricted diffusion (GRD) refers to hyperintense signal involving the cerebral cortex on diffusion-weighted images (DWI) with corresponding hypointensity on apparent diffusion coefficient (ADC) images. These changes are commonly seen following a vascular occlusion, reflecting the limitation of water molecule movement across cell membranes (restricted diffusion) due to the failure of Na⁺/K⁺-ATPase pumps (cytotoxic oedema). However, GRD can occur in several other neurological conditions as well. A thorough understanding of these conditions and their anatomic predilection plays a critical role in identifying and differentiating them from vascular thrombo-occlusion, with impact towards appropriate clinical management. This review highlights the less commonly encountered, non-stroke causes of GRD in adults with case-based examples. A tabulated chart of the patterns of cortical and subcortical involvement associated with these aetiologies is provided for a quick, pattern-based reference for daily radiological reporting.

Cerebral Pulsed Arterial Spin Labeling Perfusion Weighted Imaging Predicts Language and Motor Outcomes in Neonatal Hypoxic-Ischemic Encephalopathy

Rationale and Objectives: To compare cerebral pulsed arterial spin labeling (PASL) perfusion among controls, hypoxic ischemic encephalopathy (HIE) neonates with normal conventional MRI(HIE/MRI⊕), and HIE neonates with abnormal conventional MRI(HIE/MRI⊖). To create a predictive machine learning model of neurodevelopmental outcomes using cerebral PASL perfusion. Materials and Methods: A total of 73 full-term neonates were evaluated. The cerebral perfusion values were compared by permutation test to identify brain regions with significant perfusion changes among 18 controls, 40 HIE/MRI⊖ patients, and 15 HIE/MRI⊕ patients. A machine learning model was developed to predict neurodevelopmental outcomes using the averaged perfusion in those identified brain regions. Results: Significantly decreased PASL perfusion in HIE/MRI⊖ group, when compared with controls, were found in the anterior corona radiata, caudate, superior frontal gyrus, precentral gyrus. Both significantly increased and decreased cerebral perfusion changes were detected in HIE/MRI⊕ group, when compared with HIE/MRI⊖ group. There were no significant perfusion differences in the cerebellum, brainstem and deep structures of thalamus, putamen, and globus pallidus among the three groups. The machine learning model demonstrated significant correlation (p < 0.05) in predicting language(r = 0.48) and motor(r = 0.57) outcomes in HIE/MRI⊖ patients, and predicting language(r = 0.76), and motor(r = 0.53) outcomes in an additional group combining HIE/MRI⊖ and HIE/MRI⊕. Conclusion: Perfusion MRI can play an essential role in detecting HIE regardless of findings on conventional MRI and predicting language and motor outcomes in HIE survivors. The perfusion changes may also reveal important insights into the reperfusion response and intrinsic autoregulatory mechanisms. Our results suggest that perfusion imaging may be a useful adjunct to conventional MRI in the evaluation of HIE in clinical practice.