A Novel Automated Visual Acuity Test Using a Portable Head-mounted Display.

Significance: We developed a head-mounted display (HMD) as an automated way of testing visual acuity (VA) to increase workplace efficiency. This study raises its potential utility and advantages, analyzes reasons for its current limitations, and discusses areas of improvement in the development of this device.

Purpose: Manual VA testing is important but labor-intensive in ophthalmology and optometry clinics.

Individualized diffeomorphic mapping of brains with large cortical infarcts.

Whole brain mapping of stroke patients with large cortical infarcts is not trivial due to the complexity of infarcts' anatomical location and appearance in magnetic resonance image. In this study, we proposed an individualized diffeomorphic mapping framework for solving this problem. This framework is based on our recent work of large deformation diffeomorphic metric mapping (LDDMM) in Du et al.

Association of silent lacunar infarct with brain atrophy and cognitive impairment.

Objective: Silent lacunar infarct (SLI) is associated with cognitive decline and linked to an increased risk of stroke and dementia. We examined the association of SLI with MRI measures of cortical thickness, subcortical and lateral ventricular shapes and cognition in 285 ethnic Chinese elderly.

Methods: SLI, cortical thickness, shapes of subcortical and ventricular structures were quantified using MRI.

Abnormalities of cortical thickness, subcortical shapes, and white matter integrity in subcortical vascular cognitive impairment.

Subcortical vascular cognitive impairment (sVCI) is caused by lacunar infarcts or extensive and/or diffuse lesions in the white matter that may disrupt the white matter circuitry connecting cortical and subcortical regions and result in the degeneration of neurons in these regions. This study used structural magnetic resonance imaging (MRI) and high angular resolution diffusion imaging (HARDI) techniques to examine cortical thickness, subcortical shapes, and white matter integrity in mild vascular cognitive impairment no dementia (VCIND Mild) and moderate-to-severe VCI (MSVCI). Our study found that compared to controls (n = 25), VCIND Mild (n = 25), and MSVCI (n = 30) showed thinner cortex predominantly in the frontal cortex.

Multi-stage segmentation of white matter hyperintensity, cortical and lacunar infarcts.

Cerebral abnormalities such as white matter hyperintensity (WMH), cortical infarct (CI), and lacunar infarct (LI) are of clinical importance and frequently present in patients with stroke and dementia. Up to date, there are limited algorithms available to automatically delineate these cerebral abnormalities partially due to their complex appearance in MR images. In this paper, we describe an automated multi-stage segmentation approach for labeling the WMH, CI, and LI using multi-modal MR images.

Volume reduction in subcortical regions according to severity of Alzheimer's disease.

We investigated whether there exists a hierarchical vulnerability of subcortical structures with respect to the severity of Alzheimer's disease (AD). A total of 236 subjects (179 with AD and 57 with normal cognition) underwent 1.5-T magnetic resonance (MR) imaging.

Ultra storage-efficient time digitizer for pseudorandom single photon counter implemented on a field-programmable gate array.

Pseudorandom single photon counting is a novel time-resolved optical measurement method, which is advantageous over convention techniques in terms of data-acquisition speed and system cost. As a critical component of the pseudorandom single photon counter, the photon arriving time digitizer should be storage efficient for a high photon counting rate, while maintaining good time accuracy. We report an ultra storage-efficient time digitizer for a pseudorandom single photon counter in this paper, which is based on the asynchronous serial communication and can store the arriving time of every photon in 1-b memory space.

Pseudo-random single photon counting for time-resolved optical measurement.

We report a new time-resolved optical measurement method which combines single photon counting and the spread spectrum time-resolved optical measurement method. A laser diode modulated with pseudo-random bit sequences replaces the short pulse laser used in conventional time-resolved optical systems, while a single photon detector records the pulse sequence in response to the modulated excitation. Periodic cross-correlation is used to retrieve the impulse response.