Compare with Computed tomography (CT), Magnetic resonance imaging (MRI) is superior in anatomical delineation. This feature of MRI facilitates the improvement of radiation dose distribution for both tumor treatment and normal tissues protection in high-dose-rate brachytherapy (HDR-BT) by using MRI compared with CT-Ultrasound guided treatment planning and dosimetric evaluation. However, the application of MRI approach was limited due to the lack of positive contrast MRI line markers that could clearly delineate the lumen of the HDR applicator and therefore precisely show the path of the HDR source. We have utilized a positive-signal MRI line marker (C4 Imaging), based on a cobalt dichloride-N-acetyl cysteine complex, to determine the HDR source path. Since C4 is ideally visualized in MRI images when scanning with T1 based sequences, herein, we further investigated the capability of a newly developed MRI positive contrast HDR line marker, which was obtained when the C4 complexed was created in a saline (C4-S) solution. Imaging was performed using the common clinically relevant T1 and T2 MRI sequence.