Questions and answers
You may have many questions before, during and after an examination. During the procedure, you can ask your medical technical radiology (FMTRA) specialist or radiologist. We have compiled the most common questions about the MRI.
If you have further questions, please send us an email. We will answer your questions as soon as possible.
What happens during a PET/CT scan?
A PET/CT scan is a simple, safe examination that nuclear medicine physicians and radiologists have been performing for many years. PET/CT imaging is a two-step procedure: first, a low-dose CT is performed for attenuation correction and localisation of the target, followed directly by a PET investigation, which illuminates the metabolic information.
Does a PET/CT examination replace the CT scan?
Yes, because the CT and PET are performed in succession with the same device, information can be analysed separately and then merged.
How does the patient prepare for the procedure?
Depending on which radiopharmaceutical is used during the PET/CT examination, the patient may be asked not to eat or drink four for six hours before the examination (with the exception of water to take medication). Diabetics should please read the patient information sheet regarding medication before the PET/CT examination.
How long does a PET/CT take?
The length of the examination varies depending whether just one location is the focus or a whole-body PET/CT scan is performed. Depending on the problem, an X-ray contrast agent may be injected and a diagnostic CT performed. Plan a maximum of 90 minutes for the PET/CT examination.
When can I expect the results?
The results are sent to the referring doctor on the same day.
Will I be alone in the room?
Yes. To ensure optimum image quality, no other people should be moving about the room (this disturbs the magnetic field). Your family may sit next to you during the procedure. The radiology staff can watch you through a window and hear you through a microphone. You can also press an alarm button at any time to stop the test.
What happens if I feel claustrophobic?
The radiologist may give you a strong anti-anxiety medication, which will ensure you can complete the examination! If this is the case, you should not drive after the examination as your ability to operate a vehicle will be strongly affected.
I have metallic dental fillings and an artificial hip. Can I undergo magnetic resonance imaging?
Yes. The metal alloys used in dental fillings or inlays, joint prostheses, plates and screws (eg, those used in bone fractures) usually lead to image distortion only in the immediate area. There is no risk for patients with such implants. It has even been proven that most people with artificial heart valves can undergo an MRI investigation safely.
When should magnetic resonance imaging not be carried out?
The magnetic field is particularly dangerous for people with pacemakers. Other bio-electronic implants such as insulin pumps (artificial pancreas) or cochlear implants (inner ear prosthesis) are usually severely damaged by the MRI scanner. Further risks are presented by metal or shrapnel in the eye area and in brain tissue, and from older iron clips formerly used in vascular brain surgery. You must tell the medical technical radiology (FMTRA) specialist if you have such metals in your body.
What are the possible effects and consequences of the examination?
Is there exposure to radiation as with an X-ray or CT?
No. The MRI operates without the ionizing radiation that is used for X-rays, computed tomography or nuclear medicine.
Patients wear ear muffs or earplugs, though, to block out the noise, which is more unpleasant than harmful.
Does the scanner produce electro-smog?
The MRI testing conditions do in fact produce a strong alternating magnetic field, which is the basis of what is known as electro-smog. Apart from the significantly higher variable frequency rate, one must note that the word electro-smog refers to long-term exposure to such fields; for example, living under power lines or operation of streets and underground trains, etc. No health disorders are known related to the occasional 30-minute exposure to alternating magnetic fields.
Can children and pregnant women be examined in the MRI?
No medical disorders are known related to the examination of children or pregnant women. However, since this is a relatively new technology with no long-term experience, an MRI is performed in pregnant women with caution and only with good reason.
I have claustrophobia. Is the CT examination in the narrow tunnel?
No, the procedure using the narrow tunnel is the MRI. The scanning unit of the computed tomography, the ‘Gantry’, is like a ring through which patients are pushed. The device is open at the front and rear. People with claustrophobia rarely have problems. If you should feel claustrophobic, an anti-anxiety medication can be given. Afterwards driving ability will be limited, so in this case you should not come to the appointment by car.
Why are contrast agents needed?
Contrast agents are injected into the veins and accumulate in the perfused tissue. These tissues include the blood vessels themselves, most tumours and also inflammatory processes. In the highly perfused internal organs, pathological processes are sometimes detected due to the lesser blood flow compared with healthy tissue. Occasionally, benign and malignant foci can be distinguished through the use of contrast agents. In addition, a contrast agent drink is usually given before gastrointestinal tract imaging. It stains the intestines, so they can be distinguished from other structures in the abdominal cavity. Less commonly, contrast agents may be injected; for example, into a joint for improved delineation.
Do any CT tests not require a contrast agent?
The vast majority of examinations of the spine, skeletal system, joints, teeth and sinuses do not require a contrast agent. In studies of the brain, soft tissue of the neck, the chest and abdomen, however, contrast agent must usually be given in order to obtain optimal results.
What happens to the contrast agent after administration?
The contrast agent in the blood stream is flushed by the kidneys within 15 to 30 minutes. For faster elimination, drink plenty of fluids on the examination day. The contrast agent remains largely in the intestines and is excreted once again.
When should a CT not be carried out?
A CT must not be carried out during pregnancy because of the exposure to radiation. Other restrictions apply only to the administration of the contrast agent: for most forms of hyperthyroidism, in cases of severe previous contrast agent incompatibility, severe cardiovascular diseases, severe renal dysfunction or the bone marrow disease plasmacytoma, no contrast agent may be given.
How high is the exposure to radiation?
Computed tomography uses X-rays similar to other X-ray procedures. Differences exist in so far as the radiation is strongly defined and the exposure limited largely to the body part in question. In addition, with a CT scan many more factors affect radiation exposure than with normal X-rays: the thickness of the image slices, number of layers, sensitivity of CT detectors, size of the patient and of the examined body part, desired image quality. In summary, computed tomography radiation exposure fluctuates more than other X-ray examinations and is usually higher than for a corresponding X-ray image, but is lower than in most fluoroscopy examinations.
How much time should I plan?
If a CT of the abdomen is being performed, you must drink a contrast agent before the study to stain the intestinal tract. It takes about an hour until the contrast agent is distributed throughout the intestines. In a modern spiral CT, the actual CT slices are created within seconds, but including the time to change your clothes, position on the CT unit, place an access for the administration of contrast medium, plan the layers on the computer and subsequent image calculation, you must expect a total scan duration of 90 minutes to two hours. For all other CTs, you should calculate about 30 to 60 minutes.