Recently, a new 1.5T high field strength magnetic resonance machine (MRI) from Philips was introduced, which is one of the most advanced MRI machines used in clinical practice in China. The introduction of this technology has made MRI imaging clearer and more accurate.
1. What is MRI?
MRI is the abbreviation of Magnetic Resonance Imaging, which means magnetic resonance imaging. MRI is a new imaging method that was only applied to clinical practice in the early 80s. It has the unique advantages of no ionizing radiation, no bony artifacts, multi-directional (cross-sectional, coronal, sagittal, etc.) and multi-parametric imaging, and can display vascular structures without the use of contrast agents. It has been hailed as the next major discovery in the field of medical imaging after x-ray and CT.
2. What are the advantages of MRI examination?
MR examination is a non-invasive examination method with no radiological hazards, high soft tissue resolution, multi-parameter imaging, and better differentiation between normal and diseased tissues, thus improving the accuracy of MR diagnosis; three-dimensional imaging in any direction can be performed, making lesions more clearly displayed and more accurately located; MR vascular imaging, without contrast, can obtain complete vascular images to show various vascular diseases; especially MR angiography, without contrast, can obtain complete vascular images to show various vascular diseases, especially for the examination of brain, spinal cord, bone and joint soft tissues and body organs.
3. What is the difference between MRI and CT?
MRI is superior to CT in showing cranial, spinal and spinal cord diseases, and it can show the structure of blood vessels without the use of angiographic contrast, so it is unique in identifying blood vessels, masses and lymph nodes from each other. It also has several times higher soft tissue resolution than CT, and is sensitive to detect changes in water content in tissue components, so it is often more effective and earlier than CT in detecting lesions.
4. What are the clinical applications of MRI?
(1) Cranial brain and spinal cord: MRI is more sensitive than CT in the diagnosis of brain tumors, inflammatory brain lesions, white matter lesions, cerebral infarction, and congenital brain anomalies, and can detect early lesions and locate them more accurately. MRI can also directly display some cranial nerves, and can detect early lesions on these nerves. MRI can show the whole spinal cord directly. For intervertebral disc lesions, MRI can
MRI can show degeneration, herniation or bulging of the disc. It is also better to show spinal stenosis.
(2) Head and neck: MRI can show tumor lesions in the eye, nose, throat and throat, such as the invasion of the skull base and cranial nerves by nasopharyngeal carcinoma, which is clearer and more accurate than CT. MRI can also show the extent and characteristics of neck masses to help characterize them.
(3) Thorax: MRI can directly show the myocardium and the right and left ventricular chambers (attentive electrical gating), which can provide insight into myocardial damage and allow measurement of cardiac function. The condition of large blood vessels in the mediastinum can be clearly displayed. It is also extremely useful for localizing and characterizing mediastinal tumors. It can also show pulmonary edema, pulmonary embolism, and pulmonary tumors. It can distinguish the nature of pleural effusion and whether it is a vascular section or a lymph node. (4) Abdomen: MRI can provide very valuable information for the diagnosis of liver, kidney, pancreas, spleen, adrenal gland and other substantial organ diseases, which can help to confirm the diagnosis. MR cholangiopancreatography (MRCP) can show the bile ducts and pancreatic ducts, and can replace ERCP. MR urography (MRU) can show dilated ureters and pelvic calyces, and is especially useful for patients with poor renal function and unremarkable IVP.
(5) Pelvis: MRI can show lesions in the uterus, ovaries, bladder, prostate, seminal vesicles, and other organs. The endometrium and myometrium can be seen directly, which is very helpful for early diagnosis of tumorigenic lesions of the uterus. It is also of great value for the localization and qualitative diagnosis of lesions in the ovaries, bladder, prostate, etc.
(6) Posterior peritoneum: MRI is of great value in showing tumors of the posterior peritoneum and the relationship with the surrounding organs. It can also show lesions of the abdominal aorta or other large vessels, such as abdominal aortic aneurysm, Bu-Char syndrome, and renal artery stenosis.
(7) Musculoskeletal system: MRI shows a higher rate of damage to cartilage discs, tendons and ligaments in joints than CT. Because it is more sensitive to changes in bone marrow, it can detect bone metastasis, osteomyelitis, aseptic necrosis, leukemia bone marrow infiltration, etc. at an early stage. It shows the soft tissue mass of bone tumor clearly. It also has a certain diagnostic value for soft tissue injury.
5. What preparations should be made before MRI examination?
(1) Before entering the examination room, the patient must remove all metal objects from his body, such as watches, keys, pens, coins, glasses, literature, etc.
(1) Before entering the examination room, the patient must remove all metallic objects from the body, such as watches, keys, pens, coins, glasses, bras, and various magnetic cards.
(2) Sedation should be given to young children, irritable and depressed phobic patients.
(3) The abdominal examination is best performed on an empty stomach, with or without gastrointestinal contrast. The abdomen may be wrapped with a lap band to reduce artifacts caused by respiratory movements.
Are there any contraindications to MRI examination?
Yes, there are. A contraindication is the presence of magnetically susceptible materials or devices in the patient’s body, where movement or loss of function of these structures could cause adverse effects. For example.
(1) Cardiac pacemakers.
(2) Cochlear implants.
(3) Certain artificial heart valves.
(4) Bone growth stimulators and nerve stimulators (tens).
(5) Arterial clips or loops.
(6) Metal structures (peri-frame); (7) Certain prostheses.
(7) certain prostheses.