Evaluation of different magnetic resonance imaging contrast materials to be used as dummy markers in image-guided brachytherapy for gynecologic malignancies^*

Avaliação do uso de diferentes agentes de contraste em ressonância magnética como fontes falsas em planejamentos de braquiterapia guiados por imagem

Abstract

Objective:

To identify a contrast material that could be used as a dummy marker for magnetic resonance imaging.

Materials and Methods:

Magnetic resonance images were acquired with six different catheter-filling materials-water, glucose 50%, saline, olive oil, glycerin, and copper sulfate (CuSO₄) water solution (2.08 g/L)-inserted into compatible computed tomography/magnetic resonance imaging ring applicators placed in a phantom made of gelatin and CuSO₄. The best contrast media were tested in four patients with the applicators in place.

Results:

In T2-weighted sequences, the best contrast was achieved with the CuSO₄-filled catheters, followed by saline- and glycerin-filled catheters, which presented poor visualization. In addition (also in T2-weighted sequences), CuSO₄ presented better contrast when tested in the phantom than when tested in the patients, in which it provided some contrast but with poor identification of the first dwell position, mainly in the ring.

Conclusion:

We found CuSO₄ to be the best solution for visualization of the applicator channels, mainly in T2-weighted images in vitro, although the materials tested presented low signal intensity in the images obtained in vivo, as well as poor precision in determining the first dwell position.

Keywords:
Imaging, three-dimensional; Brachytherapy/methods; Diagnostic techniques, obstetrical and gynecological; Magnetic resonance imaging/methods; Contrast media