The Direction of Flow and Phase-encoding Schemes Effects on Signal Intensity in T1-weighted Inversion Recovery TurboFLASH Images.

Background: It is needed to minimize the effect of flow direction on the desired area, such as arterial input function (AIF) in magnetic resonance imaging (MRI).

Objective: The current study aimed to investigate the effect of flow direction on different velocities (0-80.39 cm/s) for the strength of the signal intensity (SI) at the linear phase-encoding (LPE) and the center out phase-encoding (COPE) schemes and to recommend the best flow direction in a selected slice and scheme for absolute perfusion measurement by inversion recovery T1-weighted turbo fast low-angle shot (TurboFLASH) MR images.

Effect of iron oxide nanoparticles coating type on the relationship between nanoparticles concentration and signal intensity in inversion recovery T1-weighted MRI.

Background: Ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles are used as blood pool contrast agent for magnetic resonance angiography and perfusion imaging. Our aim in this study was to investigate the effect of the two coating types of iron oxide nanoparticles on the relationship between nanoparticles concentration and signal intensity (SI) in T1-weighted MR images.

Methods: Different concentrations of the polyethylene glycol (PEG), and carboxydextran-coated iron oxide nanoparticles were imaged using inversion recovery Turbo-FLASH (Turbo fast low-angle shot) pulse sequence with inversion times (TIs) of 300-900 ms (interval of 100 ms).

Monte Carlo modeling of a conventional X-ray computed tomography scanner for gel dosimetry purposes.

Our purpose in the current study was to model an X-ray CT scanner with the Monte Carlo (MC) method for gel dosimetry. In this study, a conventional CT scanner with one array detector was modeled with use of the MCNPX MC code. The MC calculated photon fluence in detector arrays was used for image reconstruction of a simple water phantom as well as polyacrylamide polymer gel (PAG) used for radiation therapy.

Effect of Flip Angle on the Correlation Between Signal Intensity and Different Concentrations of Iron Oxide Nanoparticles Using T1-Weighted Turbo-FLASH Inversion Recovery Sequence.

Background: Ultrasmall superparamagnetic iron oxide nanoparticles have been used as a blood pool contrast agent for magnetic resonance angiography and perfusion studies. Linear relationship between signal intensity (SI) and nanoparticle concentration is essential for perfusion measurement.

Objectives: The aim of this study was to investigate the effect of different flip angles on maximum SI and the linear relationship between SI and different concentrations of iron oxide nanoparticles using T1-weighted Turbo-FLASH (fast low angle shot) inversion recovery sequence to find the optimum flip angle for perfusion measurement.

The effect of inversion times on the minimum signal intensity of the contrast agent concentration using inversion recovery t1-weighted fast imaging sequence.

Background: Inversion recovery (IR) pulse sequences can generate T1-weighted images with a different range of inversion time (TI) to suppress or null the signal intensity (SI) for a specified tissue. In this study, we aimed to investigate the effect of TI values on the concentration of the contrast agent, which leads to a minimum signal intensity, using an inversion recovery T1-weighted 3-dimensional fast-gradient echo imaging sequence.

Methods: A phantom was designed to hold 25 vials which contained different (between 0 and 19.

The Effect of Inversion Time on the Relationship Between Iron Oxide Nanoparticles Concentration and Signal Intensity in T1-Weighted MR Images.

Background: Magnetic nanoparticles have been widely applied in recent years for biomedical applications. Signal intensity (SI) of magnetic resonance (MR) images depends on the concentration of nanoparticles. It is important to find the minimum concentration of iron oxide nanoparticles that produces maximum SI and determines the minimum injection dose for clinical studies.

Effect of phase-encoding scheme on the relationship between contrast agent concentration and signal intensity on inversion recovery turbo fast low-angle shot T1-weighted images.

Previous studies have shown that the image parameters such as the repetition time and inversion time (TI) and image sequences can have an effect on the maximum linearity between signal intensity (SI) and concentration. Our aim in this study was to investigate the effect of a phase-encoding scheme (linear phase-encoding and center out phase-encoding) at different TIs on the maximum linear relationship between contrast agent concentration and SI using inversion recovery TurboFLASH (turbo fast low angle shot) T1-weighted images in MRI. A phantom was designed to hold 25 vials which contained either different (between 0 and 19.

Comparison of maximum signal intensity of contrast agent on t1-weighted images using spin echo, fast spin echo and inversion recovery sequences.

Background: MRI is not able to directly measure the concentration of contrast agent. It is measured indirectly from the signal intensity (SI). It is very important to know how much contrast agent should be injected to receive a maximum SI in the region of interest (ROI).

Effect of concentration of contrast agent on the inflow effect for measuring absolute perfusion by use of inversion recovery T₁-weighted TurboFLASH images.

Previous studies have shown that the organ blood flow (OBF) calculated from the T₁-weighted MRI technique was lower than expected. The inflow correction was one of the main corrections for measuring the absolute OBF. Our aim in this study was to investigate the influence of the contrast agent concentration on inflow effect on signal intensity (SI) and to find the gradient of different flow rates at different concentrations by use of inversion recovery T₁-weighted turbo fast low angle shot (TurboFLASH) MRI images.

Effects of inversion and saturation times on relationships between contrast agent concentrations and signal intensities of T1-weighted magnetic resonance images.

The present study was an attempt to investigate the effect of variation of inversion time (T (I)) and saturation time (T (S)) on the linear relationship between contrast agent concentration and signal intensity (SI) on Turbo Fast Low Angle Shot (TurboFLASH) T (1)-weighted images in MRI. For this purpose, inversion recovery (IR) and saturation recovery (SR) sequences (Center out Phase-Encoding acquisition) were used. A phantom was designed to hold 25 vials which contained either different (between 0 and 19.