MRI in Oncology: can a scan show cancer?
Early diagnosis is a priority trend in modern Oncology. Even cancer identified before occurred screening of atypical cells in the lymph nodes and distant organs, can be cured, while achieving long-term remission process. The emergence of methods of magnetic resonance scanning has opened new perspectives in the diagnosis of tumors.
The advantages of the magnetic resonance diagnosis for cancer patients
- high resolution – you can define the tumor with a size of 0.1-0.3 mm, that is, to detect cancer to the formation of metastases;
- the reproducibility of the result for two images taken at different times, the doctor may give an opinion on the status of the tumor dynamics;
- using an MRI with contrast, to evaluate the nature of the growth of education and to determine its vascularization, which is particularly important when the biopsy before surgery is impossible.
- harmless to the body – the magnetic field does not potentiates tumor growth, therefore the tests can be carried out repeatedly without fear of aggravating the process.
What it’s used for MRI in Oncology?
- Diagnosis of tumor at an early stage.
With the advent of magnetic resonance scanning diagnostic opportunities in Oncology has expanded considerably. Due to its high resolution can identify lesions with a diameter of 0.1 – 0.3 mm. Inspection is prescribed as a screening in the presence of risk factors, and the appearance of specific and nonspecific symptoms of tumor growth. If the photographs revealed the formation, further added contrast. This allows to determine the topography of the tumor and to do a preliminary conclusion about its nature.
- Evaluation of treatment results.
A magnetic field harmless to the body, so patients undergoing radiation therapy for cancer, do not have to worry about increasing side effects. However, it is possible to obtain a reliable picture of changes in the tumor after treatment.
- Planning of surgical intervention.
MRI not only shows the presence of the tumor, but also gives reliable information about its size, shape and relation to surrounding vessels, nerves and internal organs. Based on these images creates a three-dimensional reconstruction of the study area that actually allows the surgeon to see the surgical field at the planning stage of the operation.
- Monitoring of neoplasm in dynamics.
Removal of a tumor located near vital structures may pose a serious risk to the patient. Therefore, in the absence of aggressive growth, these tumors try to control conservatively. In this case, the magnetic scan is the optimal method for periodic monitoring, informative and harmless to the body.
Diagnosis of malignant tumors using MRI
Magnetic resonance scan is used for primary detection of cancer, planning of surgical intervention and the evaluation of the results of chemotherapy or radiation or surgical treatment in the dynamics. An experienced specialist knows what it looks like tumor on the images in various scan modes on the basis of these data we can with some degree of probability which education has.
The doctor in the description of the MRI makes a conclusion about the nature of the tumor on the basis of indirect evidence. To definitely diagnose cancer or benign education is possible only on the basis of biopsy.
Conducting an MRI, the doctor will include found the tumor to benign or malignant on the basis of indirect evidence:
- The nature of the circuit.
In most cases, benign tumors have smooth and even borders, which testifies to their expansive growth (they are pushing the surrounding tissues and pushed back those nearby structures). Fuzzy and jagged, characteristic of malignant tumors show infiltrative growth.
- Uniformity of content.
Benign tumors have a homogeneous structure, so often look like the shadow of uniform density. Malignant — contain areas of necrosis, calcification, therefore, the density of the image is non-uniform.
- The degree of vascularity and uptake of contrast.
The structure of blood vessels the doctor can see when performing MRI with intravenous enhancement. In benign tumors the vessels are arranged linearly and are not intertwined, they accumulate more contrast than surrounding tissues, but less than malignant. The cancer contains many highly branched capillaries, actively anastomosing among themselves.
Finally to differentiate the nature of education can only biopsy – microscopic examination of a fragment. The higher the qualifications of the doctor running the scan and gives a conclusion, the less likely you are to confuse benign process to cancer. However, there are tumors that look benign, but the biopsy results are malignant.
Conclusion MRI and the final diagnosis
MRI is a modern and high-precision, but still a helper method. Diagnosis matter of clinical symptoms, results of other laboratory and instrumental studies. Therefore, the detected formation (fibroma, lipoma or cancer) in the conclusion, which is handed to the patient, is not specified.
Using magnetic resonance scanning, you can make an assumption about the nature of the tumor, based on indirect signs. Muscle, adipose tissue or the epithelium gives a different MRI signal, so often it can even be assumed, from what material formed the tumor. However, to determine definitively the type of tumor and to reliably know benign or malignant, only a biopsy – microscopic analysis of a fragment of the tumor.
MRI is an auxiliary method of research, the results of which there is only a description of the image. A diagnosis can only ask the attending physician on the basis of clinical complaints and laboratory tests.
Thus, to say that with the help of MRI scan can diagnose cancer is not entirely true. The study helps to detect the tumor and gives the necessary information about its structure, and the diagnosis puts the physician on the totality of the whole clinical picture. Therefore it is not necessary to read the description of the MRI, trying to determine their own disease and see cancer if it is better to trust a diagnosis by a specialist.
The limitations of the method and possible errors
The diagnostic capabilities of MRI are dependent on the resolution of the apparatus and the professionalism of the doctor. The minimum thickness of the object rendered in the photo depends on the power of the magnetic field of the apparatus. Pictures taken on low-floor installations for MRI do not have sufficient diagnostic accuracy for early detection of tumors. On this unit the tumor may not even see a highly qualified specialist. To obtain reliable information about the presence of the mass, its form, size and proportion with the surrounding structures, it is necessary to do an MRI apparatus with the magnetic field of 1.5 Tesla.
Certain limitations in the diagnosis of diseases of the lungs and the skeletal system using MRI exist, but they are not revealing of oncological processes. Tumors of lung and bone can be detected using magnetic resonance.
Examination of the lungs and the skeletal system has its own characteristics, but to the diagnosis of cancer is irrelevant:
- Light: because of the high lightness and low fluid content on MRI is poorly visualized broncho-alveolar tissue, so the disease is accompanied by its diffuse changes, it is better to diagnose using CT. Benign tumors or lung cancer, like other focal education are well seen on magnetic resonance images.
- The bone is poor in water, and therefore in itself gives a weak signal on MRI, in contrast to the contained bone marrow. Using magnetic resonance imaging, the doctor can detect any changes in the structure of bone marrow and bone than from the tumor tissue.