Magnetic resonance imaging and computed tomography are extremely informative methods of body research. These procedures have numerous similarities and differences. If you need to undergo an abdominal examination, should you go for an MRI or CT scan?
What is AN MRI and CT scan?
Both methods involve layered studies of the body. This is why they have the term ”tomography” in their name.
Even though a general principle is used, the physical ways of obtaining images are different. Therefore, some organs and systems inside the body are more visible during X-ray computed tomography while others in magnetic resonance imagining.
Intravenous contrast amplification can be used in both procedures to assess the supply of blood to various organs or to detect pathological diseases. To perform this a catheter is placed in the elbow vein and a special contrast ”colouring” substance is introduced during ”photography”.
Computed tomography is a procedure that yields results that are very accurate especially if the study is contrasting. The resulting images show the bone structures, lymph nodes, vessels and formation of various organs of the examination area. CT scan does not need any special preparation and preliminary examinations.
The method used in computed tomography is bases on X-rays. MRI is a non-beam method of research. In magnetic resonance imagine, a person is exposed to strong magnetic fields and the basis of the image is the effect of magnetic resonance from atoms of hydrogen protons.
Both methods produce layered images and thus they can create a 3D model of the area being examined. The resulting models can be printed on a film or transferred to the media in the desired projections and scale.
Similarities and differences of procedures
Three similarities of MRI and CT
There are a few similarities in the two types of tomography and they are related to the organization of the research:
- Both procedures take place in externally similar machines – tomography – and in both the patient falls on a special moving table.
- During the study, the laboratory watches the course of the diagnostic process. If a person feels unwell, he can signal the lab technician at any time and stop the procedure. During the MRI, the patient is given a special pear to give a signal.
- Both types of tomography are often performed with a contrast substance for a clearer understanding of the nature of the identified pathology (benign or malignant). The results of the procedures is the same – a set of layered images of the examination area on a digital medium and a printed version of the doctor’s opinion. These results are also available in a private office or via an internet consultation. This is useful if you need to send the results of the study to a clinic in another city or country for consultation with your doctor.
5 differences between MRI and CT scan
These procedures have more differences than similarities and both are in the conduct and contraception:
1. Time of research. Computer tomography is performed in an average of 3-5 minutes (with contrasting reinforcement up to 15-20). While magnetic resonance imaging of the abdominal cavity can be carried out for up to 40 minutes without contrast and up to 60 minutes with it.
2. One of the limitations of MRI is the duration of the study: it is difficult to tolerate people with claustrophobia, young children, people with mental illness or acute pain and it is difficult for a person to be sedentary. After all, everything happens here as in normal photography: if the object moves, the pictures are fuzzy.
In such a situation, it is better to perform a CT. Therefore discuss with the doctor pre-pain relief or selection of an alternative method of diagnosis.
3. Sounds during the study. The MRI procedure is very loud, and the lab technician will give you noise-cancelling headphones or protective earplugs to avoid discomfort. However, the CT scan is very silent.
4. The attraction of metal by a magnetic field.
- Intracranial ferromagnetic hemostatic clips of cerebral vessels
- Aortic clips
- Ferromagnetic metal implants
- Metal structures in the anatomical area to be explored (metal plates, dystractors, etc.)
- Ferromagnetic or electronic middle ear implants
- Metal shavings in the eyes
All of these elements have magnetic properties. Before an MRI is performed, you need to present a passport to the implanted device as this will show its MRI compatibility. MRI should never be done if the patient has any metallic objects on their body such as implants, prostheses, foreign bodies and devices such as pacemakers. In computed tomography, there are no such limitations.
5. Restrictions on pregnancy. CT scan should not be performed on children and pregnant women. This is because such radiation load is not suitable for pregnant women and it can only be done when there is a vital need. The decision ca only be made by the medical board. MRI should strictly not be done in the first trimester, that is between the first 12 weeks of pregnancy. During this period, internal organs of the foetus are being formed and therefore it is not recommended to alter this environment. MRI during this period can only be performed if the authorised by the physician.
Moreover, CT scan with contrast can only be prescribed while paying attention to the kidney and thyroid glands. People who have an allergic background and diabetes should g for preliminary consultation from the endocrinologist so as to correct therapy.
If you are allergic to 4 or more allergens, you have exacerbation of asthma, severe allergic reactions in the past such as swelling of Kwinke, bronchospasm, anaphylactic shock, ensure that you notify the doctor and perform an examination in the hospital.
Preparing for abdominal studies
Before the MRI
Before studying the abdominal organs, perebia and pelvic floor, two days prior to the examination you should stop consuming foods rich in fibre and those that contribute to the formation of gas such as:
- Yeast dough
- Black bread
- Legumes and canned food
- Fizzy drinks and sweets
Before the procedure, take activated charcoal.
The examination is usually done on an empty stomach, the last meal should be taken 6 hours before the procedure. You can also take small quantities of water as well as medication. You may also be advised to take two tablets of spasmolytic drugs such as No-Spa, at least 30 minutes before the study as it will remove any air from the peristaltic movement of the intestines.
Three of four days before the CT scan, you should stop the consumption of foods that are heavy, fatty, avoid nuts, sweets and any flour products. You should also stop taking strong tea and coffee. The best diet that should be taken is boiled fish, vegetables, light soups and broths. The last meal should be taken at least 6 hours before the procedure. During the CT scan, spasmolytic may also be required to eliminate air form the peristaltic movement of the intestines.
What is the difference between the results of MRI and CT scans of the abdominal cavity?
Different MRI and CT technologies are used in the studies and therefore they are sensitive to different tissues.
Computed tomography provides more information about the dense formations, bone tissues and vascular conditions. CT scan is the best method when assessing chest organs and kidney stones.
Magnetic resonance imagine is more sensitive to soft tissues and fluids. The doctor will be able to note the early stages of the tumours, circulatory disorders, metastases, hematomas, abscesses and chronic lesions using the images.
Does the choice of procedure depend on the disease?
The first thing you should do is see a doctor as he is the only one who can assess your situation and make the right choice out of the diagnostic method.
But life sometimes dictates its adjustments and if you decide to independently pass the examination, it is important to understand the diseases that will be more informative each type of tomography.
Computed tomography should be chosen for diseases such as:
- Injuries, damage to ureters, kidneys and breaks of the renal capsule.
- X-ray stones in the kidneys and ureters, in the bile ducts.
- Weight loss, pain and other symptoms indicating possible diseases of the organs of the area.
- Signs of any pathologies detected as a result of X-rays, ultrasound and so on, requiring clarification.
- Mixed or questionable results from other studies.
- If there are contraindications to MRI.
- Enlargement of the liver (non-obvious origin).
- Symptoms of mechanical jaundice.
- Assessing the effectiveness of cancer treatment.
- Thrombosis, aneurysms, ruptures and vascular deformities.
Computed tomography is also useful when preparing for surgery as the study with contrast reveal features of the supply of blood to the organ and it allows the planning and assessment of surgery.
Magnetic tomography will produce better results in the following cases:
- Suspicions of oncology.
- The size and structure of abdominal organs: spleen and liver, gallbladder and pancreas, adrenal glands and kidneys, bile ducts and lymph nodes.
- Inflammatory, degenerative, obstructive and cystic processes.
- Circulatory disorders and heart attacks.
- Congenital abnormalities in the structure of abdominal organs.
- Malignant or benign tumours.
- Thrombosis, aneurysms, ruptures and deformities of large vessels.
- Stones and pathological changes in the bile ducts and gallbladder.
What to choose to examine the abdominal cavity – MRI or CT scan?
A doctor is the only one who can answer this question. By having a complete picture of the disease the need of certain procedures can be determined. After consultation with a specialist you can undergo an MRI or CT scan of the abdominal region.