1.5 t clinical mri scanner

MR relaxation properties were carried out using a 1.5 T clinical MRI scanner (Siemens Medical Solutions, Erlangen, Germany). For in vitro MRI measurement, suspensions of synthesized nanoparticles with concentrations ranged from 0.05 to 0.25 mM were prepared and placed in a phantom for imaging. A spin-echo sequence was utilized for the measurement of the T2 relaxation time of the samples. The T2 measurement parameters were as follows: repetition time TR = 3000 ms, echo time TE = 13.8–220.8 ms, and flip angle = 180°.

The irradiated polymer gel vials were imaged using a 1.5 T clinical MRI scanner (Siemens Avanto, Germany) after 24 h as shown in Figure 1. These vials were moved to the MRI scanning room before imaging for equilibrating at room temperature (18 °C). The MRI factors for the multiple spin-echo were as follows: echo time (TE)=20–640 ms, inter-echo time=20 ms, number of echoes=32, repetition time (RT)=6000 ms, slice thickness=3 mm and field of view (FOV)=250×250 mm². The signal intensities were measured in a circular region of interest (ROI) of each vial using the DICOM images in the MATLAB (Mathworks, R₂017a, Version 9.2.0.538062) software. The signal changes were used to calculate the spin-spin relaxation, R₂ (1/T₂) by ((S=S0e-TE/T2) . The sensitivity was calculated as the slope of the curve [ 17 (link)
, 18 (link) ].