| Magnetic Resonance Imaging (MRI) Scanner | |
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A Magnetic Resonance Imaging (MRI) scanner can create images of internal organs and pathologic tissues using magnetic fields, radiofrequency pulses, and physics/engineering knowledge/algorithms. In brief, the scanner uses suitable magnetic fields and appropriate radiofrequency pulse to excite a Hydrogen nucleus, a part of a water molecule which is abundant in a human body, at a specific location inside a patient body. The excited Hydrogen nucleus or Proton will return the energy it receives back as radiofrequency wave that can be detected by scanner receiver coils. The signals from the coils as well as the designed parameters of magnetic fields and radiofrequency pulse are used to computed for the image intensity at the specific location. After all targeted locations are investigated as above, whole images of internal organs or pathologic tissues can be reconstructed and displayed. Even though modern MRI scanners are expensive, they are widespread all over the globe at present because they are very helpful in making diagnoses using their resultant images. MRI images show distinct organs and tissues, and can be on any planes of reference (sagittal, coronal, axial, or oblique). An MRI scanner can scan any part of the patient body. In the investigation of brain and spine, MRI images give better information than CT images in general. Moreover, there are many kinds of MRI images. For examples, an MRI modality is very useful in making the diagnosis of acute brain infarction (Figure 3), another modality can be uses to measure biochemical substances (Figure 4), and MRI can be used to investigate blood vessels (Figure 5). MRI scanner does not use any ionizing ray (e.g., X-ray). Thus, it is a very useful tool to investigate pediatric patients.
Using MRI Scanner on a Patient and an Organ To be scanned by a MRI scanner, a patient must lie in the machine that looks like a short tunnel with 60 centimeter in diameter. The organ to be scanned will be covered or attached by a receiver coil set specially designed for individual organ. During being scanned, the patient will hear sound generated by switches of the scanner. The patient has to be in the scanner about 30-60 minutes, depending on the organ to be scanned. In some MRI examinations, the patient has to hold her/his breath. In addition, the patient may be asked to prepare herself/himself for the MRI examination. MRI can be used to scan nearly all organs of the body, giving excellent resultant images. However, the images from lungs and colon are generally distorted due to too much air in those organs. What You Should Know about MRI:
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