Ioannis Koktzoglou

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The presence of susceptibility-shifting media can lead to signal voids in magnetic resonance images. While signal voids have been traditionally used to detect such magnetic perturbers, selective magnetic resonance imaging of off-resonant spins surrounding susceptibility-shifted media allows for them to be visualized as hyper-intense (positive contrast)(More)
This work developed a three-dimensional (3D) diffusion-prepared segmented steady-steady free precession (DP-SSFP) cardiovascular magnetic resonance (CMR) sequence for black-blood (BB) thoracic aortic and carotid wall visualization. In 14 healthy volunteers, BB CMR of the thoracic aorta (n = 7) and carotid arteries (n = 7) was performed over 12 cm and 3 cm(More)
Signal Targeting with Alternating Radiofrequency (STAR) and STAR and Flow-Independent Relaxation Enhancement (STARFIRE) are noncontrast methods for flow-dependent and flow-independent magnetic resonance angiography (MRA). The methods rely on the acquisition and complex subtraction of two image sets alternately labeled by spatially selective or spatially(More)
Contrast-enhanced magnetic resonance angiography is routinely performed using parallel imaging to best capture the first pass of contrast material through the target vasculature, followed by digital subtraction to suppress the appearance of unwanted signal from background tissue. Both processes, however, amplify noise and can produce uninterpretable images(More)
We performed technical optimization followed by a pilot clinical study of quiescent-interval single-shot MR angiography for peripheral vascular disease. Quiescent-interval single-shot MR angiography acquires data using a modified electrocardiographic (ECG)-triggered, fat suppressed, two-dimensional, balanced steady-state, free precession pulse sequence(More)
PURPOSE To evaluate a rapid sub-millimeter isotropic spoiled gradient-echo (nonselective SPGR) to facilitate the brain subcortical segmentation and the visualization of brain volume compared with the commonly accepted inversion recovery-prepared SPGR (SPGR-IR) technique. MATERIALS AND METHODS The feasibility of the nonselective SPGR was evaluated for two(More)
PURPOSE To develop a navigator technique enabling free-breathing acquisition to afford sufficient signal averaging for quantitative renal perfusion measurement using arterial spin labeling MRI. METHODS A novel two-dimensional (2D) navigator technique was implemented in concert with flow-sensitive alternating inversion recovery (FAIR) preparation and true(More)
PURPOSE We hypothesized that non-contrast-enhanced MR angiography (NEMRA) could be performed without cardiac gating by using a variant of the quiescent-inflow single-shot (QISS) technique. METHODS Ungated QISS (UnQISS) MRA was evaluated in eight patients with peripheral arterial disease at 1.5T. The radial acquisition used optimized azimuthal equidistant(More)
BACKGROUND Coronary magnetic resonance angiography (MRA) is usually obtained with a free-breathing navigator-gated 3D acquisition. Our aim was to develop an alternative breath-hold approach that would allow the coronary arteries to be evaluated in a much shorter time and without risk of degradation by respiratory motion artifacts. For this purpose, we(More)
BACKGROUND Cardiac and navigator-gated, inversion-prepared non-enhanced magnetic resonance angiography techniques can accurately depict the renal arteries without the need for contrast administration. However, the scan time and effectiveness of navigator-gated techniques depend on the subject respiratory pattern, which at times results in excessively(More)