Definition
Magnetic resonance imaging, or MRI for short, is an imaging procedure that is widely used in medicine in particular. With the help of a strong magnetic field, organs, tissue and joints can be displayed in the form of sectional images during an MRI examination and finally evaluated for pathological changes. Due to its good soft tissue contrast and high resolution, the MRI of the pelvis is well suited for imaging organs of the pelvis, such as: For this reason, the MRI examination of the pelvis is nowadays an extremely important diagnostic tool and is performed for a variety of diseases of the pelvic organs.
- The rectum
- The urinary bladder and
- The prostate in men and
- The uterus and
- The ovaries in the woman.
MRI of the pelvis is a non-invasive imaging procedure. This means that no instruments need to be inserted into the body to visualize the organs of the pelvis, such as the rectum, bladder, prostate, uterus or ovaries. The MRI of the pelvis works with the help of a strong magnetic field.
Put simply, the magnetic field generated by the MRI machine causes excitation of atomic nuclei, especially hydrogen atoms, in the patient’s tissue under examination. The hydrogen atoms are excited to a certain movement and thereby emit a measurable electrical signal. These measured signals are then converted into image information.
Since different tissues have a different content of hydrogen atoms and hydrogen atoms behave differently depending on the tissue, it is possible to differentiate between different tissues using MRI. The differentiation of different tissues can be simplified by the additional administration of a contrast agent, for example the well-tolerated gadolinium DTPA. Finally, the image shows the different tissues in different shades of grey.
Compared to other imaging methods, such as X-ray or computed tomography (CT), the MRI is characterized by a better soft tissue contrast, which is caused by a different water and fat content of different tissues and is therefore very well suited for imaging the pelvic organs, such as the rectum, bladder, prostate, uterus or ovaries. Another advantage over other imaging procedures is that the MRI of the pelvis works with the help of a magnetic field and does not use harmful X-rays or ionizing radiation. The disadvantages, however, are the high time required for an MRI examination and the high power consumption of the MRI machine.
An MRI of the pelvis can be performed in a hospital or in a radiological practice. Before an MRI of the pelvis can be performed, it must be clarified whether the patient is carrying metal-containing objects with him/her, as these can be destroyed by the MRI examination, impair the image, but also cause injuries to the patient. This is done on the basis of an interview with the doctor or the nursing staff.
Asking the patient about metal-containing objects is extremely important because the MRI of the pelvis works with a strong magnetic field that attracts metal-containing objects. If these objects are attracted during the MRI examination, they can damage the MRI machine and cause injury to the patient. This is especially the case with implanted metal parts, such as pacemakers, dental prostheses or piercings.
In addition, the metal parts in the MRI machine can heat up considerably and thus cause burns to the patient. For these reasons, all objects that could contain metal should be placed in a cubicle before an MRI examination of the pelvis. These include items of clothing with metal zippers, buttons or rivets, watches, jewelry, keys, check or credit cards.
Cosmetic products can also contain metal particles, which can lead to local burns, so make-up should be removed before an MRI of the pelvis. If metal-containing objects, such as a pacemaker or a prosthesis (with the exception of hip and knee prostheses) cannot be removed, the MRI of the pelvis must generally not be performed. Here, an individual decision by the physician is required.
An MRI of the pelvis can be performed without contrast medium (native) and with contrast medium. If the administration of contrast medium is necessary, for example for more detailed imaging of various tissues, this is applied at the beginning of the examination via a vein in the arm or hand.The contrast medium allows blood vessels to be better separated from muscles and other surrounding tissue. The administration of contrast medium is important for the diagnosis of tumors of the pelvic organs, such as bladder cancer or prostate cancer.
Tumors are usually heavily supplied with blood, so that during an MRI examination of the pelvis with the administration of contrast medium, the contrast medium also accumulates in the tumor, making tumors of the pelvic organs more visible. A frequently used contrast medium is the so-called gadolinium DTPA, which is generally well tolerated. In many cases, two MRI images are taken, first without contrast medium (native) and then with contrast medium.
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