Desenvolvimento de um dispositivo de teste dinâmico para avaliação da estabilidade de imagens de ressonância magnética funcional

Abstract

Among the protocols for quality control of magnetic resonance equipment is to evaluate the stability of the sequence EPI (Echo-Planar Imaging), this used in imaging method called functional magnetic resonance imaging. Nowadays, static and homogeneous test devices are recommended for this review. This work proposes the development of a dynamic test device for quality control of the stability of EPI sequences. The test device consists of an acrylic box, where two brackets are inserted, through which passes a tube in which a liquid circulates signal producing. At certain times during acquisition, is injected through a fuel injection pump, a solution of copper sulfate and gadolinium in order to produce variations in signal intensity in the region of the hose, over time. To validate the device, images were acquired in a magnetic resonance with 3.0 T during the period of a month, on Monday morning and evening and on Tuesday morning in order to evaluate machine wear. For each acquisition were evaluated: (1) the standard deviation of average normalized signal intensity in the region of the images corresponding to the homogeneous region of the liquid; (2) the average normalized signal intensity at baseline and injection in the image region corresponding to the hose; (3) the difference between the mean of baseline and injection; (4) the signal to noise ratio in the region of the images corresponding to the homogeneous region. As a result there was an increase in the standard deviation in the homogeneous region of the liquid from the acquisitions made on Monday evening. There was also wide variation in the difference between the baseline and injection line, and in one day this went from approximately 0.3 to 0.6 after five acquisitions and on another day of approximately 0.7 to 0.5 after a single acquisition. The test has been validated for use in 3.0 T equipment and that additional tests are needed to verify the reproducibility of the results