TITLE:
Assessment the Optimal Effect of Time of Repetition: Extrinsic Pulse Parameter on Gd-DTPA Enhanced, Spin-Echo T1-Weighted MR Images under Low Magnetic Field Strength
AUTHORS:
Bimali Sanjeevani Weerakoon, Toshiaki Osuga, Takehisa Konishi
KEYWORDS:
Gd-DTPA Concentration, Spin Echo Pulse Sequence, Signal Intensity, Time of Repetition, T1-Weighted Images, Low Field MRI
JOURNAL NAME:
International Journal of Medical Physics, Clinical Engineering and Radiation Oncology,
Vol.5 No.3,
August
31,
2016
ABSTRACT: The
contrast agent concentration, the time of repetition (TR) and magnetic field
strength are significant parameters that influence for the accurate signal
intensity (SI) in quantitative Magnetic Resonance Imaging (MRI). Therefore,
this study was conducted to investigate and refine the dependence and the
optimal effect of Time of Repetition (TR) on the relationship between signal
intensity and Gd-DTPA (Gadolinium-diethylene-triaminepenta-acetic acid)
concentration, after applying two-dimensional (2D) Spin Echo (SE) pulse sequence
under low-field MRI. In addition to that, the optimal concentration of Gd-DTPA
at given sequence parameters at low-field MRI was also evaluated. A
water-filled phantom was constructed for a range of Gd-DTPA concentrations (0 -
6 mmol/L) and the mean signal intensities (SIs) were assessed in the defined
region of interest on T1-weighted images with different TR values (40 - 2000
ms). The generated signal-concentration curves for Gd-DTPA revealed that
increasing TR was associated with the increase of the overall SIs and the
maximum relationship between SI to concentration. Moreover, the required
Gd-DTPA concentration to produce the maximum SI was associated to decrease with
the increase of TR. In addition to this, the application of beyond 100 ms TR
values in this study with relatively higher concentrations (beyond 1 - 2
mmol/L) has resulted predominantly non-linear patterns in the
signal-concentration curves and it appears the saturation or decay of the SIs
due to T2 effect. From these results, it can be suggested that the selection of
relatively lower Gd-DTPA concentration (
mmol/L)
with less than 800 ms (