Magnetic resonance imaging (MRI) Radio frequency and magnetic field imaging

Although computed tomography scan (CT) is the image exam mostly used in diagnostic investigation in Urology (on par with ultrasound), magnetic resonance (MRI) has been assuming a greater importance in the genito-urinary imaging evaluation, as the quality of its resolution is increasing.


The great advantage of this technique is that, even though it completely dispenses the use of ionizing radiation, as well as, in many situations, the use of intravenous contrast, an excellent resolution in soft tissue contrast is obtained. Thus, it is the technique of choice for pregnants and patients with renal insufficiency or with allergy to iodinated contrast.


It is an image examination that is based on a complex technology.

Briefly, for obtaining MRI images, exposure to a magnetic field with high strength is necessary, allowing the orientation of the protons of free water molecules, existing in the cells of the patient to be examined, according to an axis oriented from the head to feet - this is the reason for the “tunnel” where the positioner is, where the patient is placed. This tunnel is surrounded by a large and very powerful magnet. Placing a radio frequency antenna over the body area to be studied, pulses of radio frequency are emitted that pass through the organism. When this emission is stopped, the protons of the water molecules release their energy, which is detected and processed into MRI images.

These images are differential in the way energy is released, that is, quickly or slowly, being images in which the water content appears light or dark, respectively.


The main disadvantages, compared to CT, are the longer duration of the exam, the loud noise, the feeling of confinement in a tight space, which can trigger claustrophobia, and the incompatibility of use in patients with some types of implanted material, such as some prostheses and some types of pacemakers.

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2 - The published articles were produced by specialists based on the recommendations and guidelines of clinical practice of the European Association of Urology (EAU), at the date of the last review;

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