Biomedical subjects

Yuko Fukuya

Publications and source records attributed to Yuko Fukuya.

3 recordsLinked to original sources

PubMed2006

[Optimization of three-dimensional triple IR fast spoiled gradient recalled acquisition in the steady state (FSPGR) to decrease vascular artifact at 3.0 Tesla].

The purpose of this study was to decrease vascular artifacts caused by the in-flow effect in three-dimensional inversion recovery prepared fast spoiled gradient recalled acquisition in the steady state (3D IR FSPGR) at 3.0 Tesla. We developed 3D triple IR (3IR) FSPGR and examined the signal characteristics of the new sequence. We have optimized scan parameters based on simulation, phantom, and in-vivo studies. As a result, optimized parameters (1st TI=600 ms, 3rd TI=500 ms) successfully have produced the vessel signal at more than 40% reduction, while gray-white matter contrast was preserved. Moreover, the reduced artifact was also confirmed by visual inspection of the in-vivo images for which this condition was used. Thus, 3D 3IR FSPGR was a useful sequence for the acquisition of T1-weighted images at 3.0 Tesla.

Adult↗

PubMed2006

[Vessel contrast and saturation effect at three Tesla in three-dimensional time of flight magnetic resonance angiography].

The purpose of this study was to clarify the effects of the increased field strength of 1.5T vs. 3.0T on blood vessel contrast and saturation in 3D time of flight MR angiography. Vessel contrast and saturation effect were evaluated for various flow velocities and flip angles using a steady-state flow phantom. The results showed increased vessel contrast and decreased saturation of blood on 3.0T compared to 1.5T, due to the following factors: 1) sufficient saturation of stationary tissue by extended T1 relaxation time, 2) increased signal-to-noise ratio (SNR), and 3) high in-flow effect. However, the blood signal on 3.0T revealed a strong tendency to phase dispersion compared to that of 1.5T. Therefore, in order to exploit the characteristic of high field strength in 3.0T, it is suggested that adequate consideration of these factors is important in setting the image acquisition parameters.

Imaging, Three-Dimensional↗

PubMed2003

[Dynamic contrast-enhanced T(1) measuring MRI using variable flip angle SPGR].

We modified the multi-phase spoiled gradient recalled echo (SPGR) pulse sequence using the double-echo MR technique for estimation of T(1) during the first pass of contrast agent, and examined its precision. In the first half of the pulse sequence, the flip angle was varied systematically to calculate static T(1) values. It was necessary to choose optimal flip angles to minimize the calculation error of static T(1) values. In the latter half of this sequence, changes in absolute T(1) were calculated using differences in signal intensities before and after the injection of contrast agent. The optimal flip angle was 20 degrees for precise conversion to T(1) values under the short TR (33.3 ms) condition. Double echo MR data were used to minimize the T(2)* effect. The present method appears to be useful for quantitative estimation of dynamic contrast-enhanced MRI.

Brain Neoplasms↗