Susceptibility-weighted imaging and transcranial Doppler ultrasound in patients with cerebral small vessel disease

Ray theory-based compounded plane wave ultrasound imaging for aberration corrected transcranial imaging: Phantom experiments and simulations

Compounded plane wave imaging (CPWI) allows high-frame-rate measurement and has been one of the most promising modalities for real-time brain imaging. However, ultrasonic brain imaging using the CPWI modality is usually performed with a worn thin or removal of the skull layer. Otherwise, the skull layer is expected to distort the ultrasonic wavefronts and significantly decrease intracranial imaging quality. The motivation of this study is to investigate a CPWI method for transcranial brain imaging with the skull layer. A coordinate transformation ray-tracing (CTRT) approach was proposed to track the distorted ultrasonic wavefronts and calculate the time delays for the ultrasound plane wave passing through the skull layer. With an accurate correction for the time delays in beamforming, the CTRT-based CPWI could achieve high-quality intracranial images with the presence of skulls. The proposed CTRT-based CPWI method was verified using a simplified three-layer transcranial model. The full-wave simulation demonstrated that CTRT could accurately (i.e., relative percentage error less than0.18%) track the distorted transmitting wavefront through skull. Compared with the CPWI without aberration correction, the CTRT-based CPWI provided high-quality intracranial imaging and could accurately localize intracranial point scatterers; specifically, positioning error decreases from 0.5 mm to 0.1 mm on average in the axial direction and from 0.7 mm to 0.1 mm on average in the lateral direction. As the compounded angles increased in the CTRT-based CPWI, the contrast improved by 16.2 dB on average for the region of interest, and the array performance indicator (representing resolution) decreased by 4.0 on average for the intracranial point scatterers. The CTRT is of low computational cost compared with full wave simulation. This study suggested that the proposed CTRT-based CPWI might have the potential for real-time and non-invasive transcranial aberration-corrected imaging.

Triglyceride-glucose index and cervical vascular function: outpatient-based cohort study

OBJECTIVES

The purpose of this study was to investigate the correlation between triglyceride-glucose (TyG) index and cervical vascular function parameters in the general population without cerebrovascular disease.

MATERIALS AND METHODS

This was a cross-sectional study that recruited a total of 1996 participants without cerebrovascular disease. TyG index was calculated based on fasting triglycerides and glucose. All patients were divided into two groups based on the median TyG index: the high TyG group and the low TyG group. The differences in basic clinical characteristics and neck vascular function parameters between the two groups of participants were compared, and then the correlation between TyG index and neck vascular function parameters was investigated.

RESULTS

Participants with a high TyG index had lower systolic, diastolic, and mean flow velocities in the basilar, vertebral, and internal carotid arteries compared with those with a low TyG index. Participants with a high TyG index had higher pulsatility index in the left vertebral artery and right internal carotid artery, but this difference was not observed in the basilar artery. In addition, TyG index was significantly negatively correlated with systolic, diastolic, and mean flow velocities in the basilar, vertebral, and internal carotid arteries, and the correlation remained after adjusting for confounding factors.

CONCLUSION

In the general population, there was a well-defined correlation between TyG index and cervical vascular function parameters, and increased TyG index was independently associated with reduced cervical vascular blood flow velocity.

Changes in cerebral arterial pulsatility and hippocampal volume: a transcranial doppler ultrasonography study

The physiological mechanisms of age-related cognitive decline remain unclear, in no small part due to the lack of longitudinal studies. Extant longitudinal studies focused on gross neuroanatomy and diffusion properties of the brain. We present herein a longitudinal analysis of changes in arterial pulsatility - a proxy for arterial stiffness - in two major cerebral arteries, middle cerebral and vertebral. We found that pulsatility increased in some participants over a relatively short period and these increases were associated with hippocampal shrinkage. Higher baseline pulsatility was associated with lower scores on a test of fluid intelligence at follow-up. This is the first longitudinal evidence of an association between increase in cerebral arterial stiffness over time and regional shrinkage.

Perivascular abnormalities in pediatric encephalopathy with fulminant brain edema

BACKGROUND

Acute encephalopathy with acute brain swelling (ABS) is a recently proposed disease of unknown etiology, characterized by rapid progression to whole-brain swelling. To our knowledge, we reported the first case of a patient with acute encephalopathy with ABS wherein brain magnetic resonance imaging (MRI) abnormalities were noted prior to the diffuse brain swelling onset.

CASE PRESENTATION

An 11-year-old boy was admitted to our unit owing to prolonged disturbance of consciousness following febrile status epilepticus. At the initial visit, the vital signs were within the normal range, except for the body temperature and consciousness level (Glasgow Coma Scale 6; E1V1M4). The initial laboratory results showed elevated inflammatory marker levels and mild hyponatremia. Cerebrospinal fluid analysis revealed albuminocytologic dissociation, whereas the myelin basic protein level was not elevated. Electroencephalography showed diffuse, high-amplitude slow waves. No abnormalities were detected on the initial brain computed tomography (CT) scan. However, at 11 h after the seizure onset, diffuse hyperintense lesions were observed throughout the cerebrum on T2-weighted brain MRI. The patient was diagnosed with acute encephalopathy and received methylprednisolone-pulse therapy (1 g) with high-dose gamma globulin (1 g/kg) administration. At 14 h after the seizure onset, the patient was declared brain-dead; the brain CT findings revealed whole-brain swelling and herniation.

CONCLUSION

Our findings were suggestive of a perivascular pathophysiology and may be used for subtyping acute encephalopathy. In cases where such findings are observed, subsequent development of severe diffuse brain swelling should be considered.

Association Between the Angiotensin-Converting Enzyme I/D Polymorphism and Risk of Cerebral Small Vessel Disease: A Meta-Analysis Based on 7186 Subjects

INTRODUCTION

Cerebral small vessel disease (CSVD) causes a quarter of all strokes and is the most common pathology underlying vascular dementia. However, the mechanism of CSVD remains unclear. Numerous studies have investigated whether the angiotensin-converting enzyme (ACE) intersection/deletion (I/D) polymorphism influences the risk of CSVD, but the results are controversial.

METHODS

We searched English and Chinese databases and calculated the odds ratio (OR) and 95% confidence interval (CI) to examine the existence of genetic associations between the ACE I/D polymorphism and the risk of CSVD. All relevant studies were screened and meta-analyzed using Review Manager 5.4.

RESULTS

A total of 27 studies involving 7,186 subjects were identified for the meta-analysis. The results of five genetic models showed a significantly increased risk of CSVD (allelic, OR=1.30; recessive, OR=1.41; dominant, OR=1.34; homozygous, OR=1.55 and heterozygous OR=1.22) in the overall analysis. Furthermore, in subgroup analysis, increased CSVD risks were also observed in Asian and Caucasian populations. We also found no relationship between ACE I/D and leukoaraiosis (LA) in patients with lacunar infarction (LI).

CONCLUSION

The ACE I/D polymorphism was positively associated with CSVD in both populations. However, this polymorphism did not increase the risk of LA in LI patients.