Chang-Ki Kang

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Hypertension may increase tortuosity or twistedness of arteries. We applied a centerline extraction algorithm and tortuosity metric to magnetic resonance angiography (MRA) brain images to quantitatively measure the tortuosity of arterial vessel centerlines. The most commonly used arterial tortuosity measure is the distance factor metric (DFM). This study(More)
BACKGROUND Noninvasive magnetic resonance angiography using ultra-high-field magnetic resonance imaging has recently provided us with the potential to image cerebral microvascular structures such as the lenticulostriate arteries. However, most studies using ultra-high-field magnetic resonance angiography have been limited to the visualisation of(More)
The effect of caffeine as a cognitive enhancer is well known; however, caffeine-induced changes in the cortical regions are still not very clear. Therefore, in this study, we conducted an investigation of the activation and deactivation with blood-oxygenation-level-dependent (BOLD) functional magnetic resonance imaging (fMRI) and of metabolic activity(More)
Hypertension, a major risk factor for stroke, is associated with altered arterial anatomy and function; however, the limited resolution of current imaging techniques has restricted the in vivo study of microvascular changes in the brain. In this report, we quantitatively examined the lenticulostriate arteries in hypertensive patients using ultrahigh-field(More)
BACKGROUND AND PURPOSE We sought to examine the feasibility of observing the lenticulostriate arteries (LSAs) noninvasively by ultrahigh-field MRI with 7.0T. METHODS We used 3-dimensional time-of-flight MR angiography with a radiofrequency coil optimized for 7.0T MRI. We examined the LSAs of 6 healthy subjects and compared 7.0T MR angiography images with(More)
OBJECTIVE Arterial stiffness is a common change associated with aging and can be evaluated by measuring pulse wave velocity (PWV) between sites in the arterial tree, with the stiffer artery having the higher PWV. Arterial stiffness is associated with the risk of stroke in the general population and of fatal stroke in hypertensive patients. This study is to(More)
Accurate 3D models of the human brain vessels can greatly help to diagnose serious diseases. Such models can be constructed by segmentation of 3D MRA images, especially the recently introduced high resolution 7T MRA. We propose a new two-step approach for fully automatic segmentation of 7T MRA images of the human cerebrovascular system. First, a 3D(More)
Segmentation of 3D cerebral vasculature is important for clinical diagnosis. However, many relevant thin vessels are not visible in 1.5T and 3T MRA. With the recent introduction of 7T MRA, images of higher resolution can be acquired, which contain much more thin vessels. We propose a fully automatic hybrid approach for segmenting vessels from 7T MRA images(More)
The present study proposes a novel functional magnetic resonance venography (fMRV) method to examine changes in venous dynamics that are difficult to detect with commonly used MRV methods such as susceptibility-weighted imaging (SWI). We used a fast gradient echo imaging sequence, known as a time-resolved angiography with interleaved stochastic(More)
BACKGROUND Small vessel diseases have been studied noninvasively with magnetic resonance imaging. Direct observation or visualization of the connected microvessel to the infarct, however, was not possible due to the limited resolution. Hence, one could not determine whether vessel occlusion or abnormal narrowing is the cause of an infarct. METHODS In this(More)