What exactly is an MRI scan?
Magnetic resonance imaging has become more and more commonly used in major hospitals, but some patients still don't know much about it. Let's unravel the mystery of MRI examination together with you.
What is Magnetic Resonance Imaging (MRI)?
Magnetic resonance imaging, in layman's terms, is to apply a magnetic field on your body to make the hydrogen nuclei in your body face the direction of the magnetic field, and then remove the magnetic field to capture the energy released by these nuclei returning to their original state to form MR signals. Then the different organs can be distinguished.
Is there any radiation in MRI examination?
No radiation. The principle of magnetic resonance mainly depends on the high-frequency magnetic field generated by current excitation, which is different from the principle of ionizing radiation formed by X-ray examination. At present, medical science has not found that magnetic resonance commonly used in clinical practice will have adverse effects on the human body.
What is the difference between plain and enhanced MRI scans?
Generally speaking, plain scan is an inspection without injection, and enhanced scan is what we often say requires an injection before inspection, the purpose is to inject gadolinium-containing contrast agent into the blood vessel. The enhanced scan is done on the basis of the plain scan. The purpose is to compare the changes of the lesion before and after the enhancement and provide more evidence for the diagnosis. Therefore, it is necessary to ensure that there is a recent plain scan for comparison before the enhanced scan.
What are the advantages of MRI?
1. The most prominent advantage is that MRI can distinguish different soft tissues very well. For example: it can clearly distinguish soft tissue structures such as muscles, tendons, fascia, and fat, and can accurately distinguish between gray matter and white matter.
2. Capable of multi-directional slices (including transverse, coronal, sagittal, without changing the position of the examinee).
3. Multi-plane, multi-parameter imaging technology, so it can clearly show the location and range of the lesion and the relationship with the surrounding tissues and organs, so that the lesion can be accurately determined. Therefore, it has unique advantages in the qualitative, localization and quantitative diagnosis of many lesions.
4. It is a non-invasive technology, and there is no X-ray radiation damage, and it really avoids other imaging examinations, such as X-ray or radionuclide scanning imaging and other radiation damage to the human body.
What diseases are MRIs suitable for detecting?
Head: tumor, vascular disease (infarction, hemorrhage), inflammation, trauma, developmental malformation, white matter lesion, etc.
Neck: Various benign and malignant tumors of the neck.
Chest: Mediastinal tumors, heart and great vessel lesions, etc.
Abdomen: liver tumors, hemangiomas, cysts, inflammatory lesions, pancreatic tumors, kidney tumors, cysts, adrenal tumors, splenomegaly, etc.
Pelvic cavity: ovarian cysts, ovarian tumors, endometriosis, uterine fibroids, uterine cancer, benign prostatic hyperplasia, prostate cancer, seminal vesicle lesions, bladder tumors, etc.
Spine: Spinal cord trauma, herniated intervertebral disc, intraspinal tumor, spinal cord tumor, spinal cord developmental deformity, spinal cord inflammation, vertebral body tumor, vertebral body inflammatory disease, etc.
Limbs and joints: meniscus injury, tendon injury, joint effusion, bone tumor, avascular necrosis of the femoral head, osteoinflammatory disease, muscle tumor, etc.
What are the precautions for MRI examination?
1. The magnet room is a strong magnetic field environment. In order to ensure personal safety, patients (including family members) who install or carry the following items and devices in the body cannot enter the magnet room: cardiac pacemaker, defibrillator, artificial heart valve, aneurysm surgery Metal clips, any electronic devices implanted in the body, metal sutures, hearing aids, cochlear implants, insulin pumps, gastric tube negative pressure drainage boxes, removable dentures, internal shrapnel or iron sand, etc.
2. Within five meters around the MRI machine, there is a strong magnetic field. Patients and family members are strictly prohibited from bringing ferromagnetic items and electronic products into the examination room, including: watches, mobile phones, keys, lighters, coins, hair clips, glasses, etc. Beds and wheelchairs are strictly prohibited from entering the magnet room.
3. Critically ill patients with claustrophobia, pregnancy, restlessness, severe trauma, life support and rescue cannot undergo MRI examination.
4. Patients with a history of surgery and patients with fixed dentures, tattoos, IUDs, eyeliner tattoos, etc. should inform the doctor before the examination.
5. For patients undergoing neck, chest, waist, abdomen, hip and other parts of the examination, clothes with iron hooks, iron buckles, and zippers should be removed first, and it is advisable to wear clothes made of pure cotton; fasting for 6 hours before MRCP examination, No water.
6. Patients with fever (body temperature above 38 degrees Celsius) are not suitable for this examination.
