Protecting the health of the elderly, MRI examination can help - examination principles and indications

Author: Wang Xuan, deputy chief physician, Peking Union Medical College Hospital

Reviewer: Feng Feng, Chief Physician, Peking Union Medical College Hospital

Magnetic resonance imaging (MRI) is an advanced medical imaging technology that can help diagnose and monitor a variety of common diseases and protect the health of the elderly. Understanding the necessity, precautions and process of the examination will help the elderly and their families cooperate with doctors to better complete the examination. Today, the "Xieying Puhui" science popularization team of the Department of Radiology of Peking Union Medical College Hospital (the original plan of Xiehexing) will take you to understand the things about MRI examinations for the elderly, so that the elderly can be worry-free and their families can feel at ease.

Our introduction is divided into three parts: the principle of magnetic resonance imaging, common situations in which the elderly need to undergo MRI examinations; preparations before MRI examinations for the elderly; and the specific process of MRI examinations for the elderly.

Figure 1 Staff positions an elderly patient for scanning (head first) (copyright image not authorized for reproduction)

Let's take a brief look at the principle of magnetic resonance. The magnetic resonance imaging device used in clinical practice is like a huge camera. It uses strong magnetic fields and radio frequency pulses to make the hydrogen nuclei in the human body produce resonance signals, thereby receiving and processing to generate images. In the human body, the number of hydrogen atoms is very large, especially in water and fat. When the magnetic resonance imaging device generates a strong magnetic field, the hydrogen nuclei are attracted to a specific direction and arranged neatly. Then, the radio frequency pulse is like a commander giving orders, instructing the hydrogen nuclei to "dance". Under the action of strong magnetic fields and radio frequency pulses, the spin state of the hydrogen nuclei changes, absorbing energy and entering an excited state. When the radio frequency pulse stops, these hydrogen nuclei return to their original queue positions like children from a cheerful spinning dance, while releasing the stored energy. The signals generated when the hydrogen nuclei release energy are captured by the magnetic resonance imaging device and processed by a computer to eventually form an image reflecting the internal structure of the body.

Unlike X-rays and CT scans, MRI does not emit ionizing radiation, making it safer for the human body. Initially, MRI technology was called nuclear magnetic resonance, which stems from its physics basis, which is to generate images by observing the behavior of atomic nuclei in a magnetic field. As mentioned earlier, clinical MRI is based on hydrogen nuclei, so the word "nuclear" in nuclear magnetic resonance refers to the hydrogen nuclei that naturally exist in the human body, such as the hydrogen in the water molecule H2O, rather than the "nucleus" used as a lethal weapon such as a nuclear bomb. Because the word "nuclear" may cause misunderstandings and fears about nuclear radiation, in 1984, experts decided to change the name to magnetic resonance imaging to eliminate public concerns. Since then, the term magnetic resonance imaging has been used to this day. Please rest assured that MRI examinations do not cause radiation and have no known side effects on the human body.

Figure 2 Staff place the body coil for a patient undergoing abdominal examination (feet first) (copyrighted image not authorized for reproduction)

The elderly population often faces the following health problems, and MRI examinations are particularly important in these cases.

1. Nervous system diseases : such as stroke, dementia, etc. Magnetic resonance imaging can help evaluate brain blood flow, detect cerebral infarction and brain atrophy. The nervous system is the earliest human system to use magnetic resonance imaging, and rich clinical experience has been accumulated. Magnetic resonance imaging is relatively accurate in locating and qualitatively diagnosing various lesions, and can detect many early and small lesions.

2. Musculoskeletal diseases : such as arthritis, fractures, etc. Magnetic resonance imaging can clearly display soft tissue structures and lesions, such as intervertebral disc lesions, bone marrow edema, and whether compression fractures caused by osteoporosis are fresh fractures.

3. Tumor diagnosis and follow-up : such as abdominal and pelvic, head and neck tumors, etc. Magnetic resonance imaging can provide more information on tissue composition and function, help detect tumors, diagnose and identify them, and follow up to monitor the efficacy.

4. Cardiovascular system diseases : such as coronary heart disease, cardiomyopathy, aortic aneurysm, arterial stenosis, etc. Magnetic resonance imaging can non-invasively evaluate heart structure, myocardial thickness and cardiac function, and evaluate vascular morphology and other information.

In the following articles, we will continue to introduce the second and third parts, the preparation before and examination process of MRI examination. We look forward to your attention.

MRI is a safe and non-invasive examination method that can provide important information for the diagnosis of diseases in the elderly, especially in cases where high-resolution soft tissue imaging is required. I hope that this series of articles can help the elderly and their families better understand and prepare for MRI examinations, so as to obtain the best health protection.