What is the meaning of long T 1 long T2 signal shadow in NMR?

According to the principle of action, MRI contrast agents can be divided into longitudinal relaxation contrast agents (T 1 preparation) and transverse relaxation contrast agents (T2 preparation). T 1 Preparation Through the direct interaction between hydrogen nuclei in water molecules and paramagnetic metal ions, T 1 is shortened, thus enhancing the signal and making the image brighter.

T2 preparation can shorten T2 by interfering with the inhomogeneity of external local magnetic environment, so that adjacent hydrogen protons can rapidly generate phase during relaxation, thus weakening the signal and darkening the image.

According to the magnetic composition, MRI contrast agents can be divided into paramagnetic, ferromagnetic and superparamagnetic. Gadolinium contrast agent commonly used in clinic belongs to paramagnetic contrast agent.

At present, six kinds of small molecular gadolinium complex contrast agents have been applied in clinic, namely: (NMG) 2 [GD (DTPA) H2O]] (Magnevist), Gd(DTPA-BMA)( Omniscan), (NMG) [GD (DOAREM), GD (HP). (NMG)2[Gd(BOPTA)(H2O)](multi Hance)，Gd(DO3A-butrol)(H2O) (Gadovist)

Extended data

Discover the lesion

Magnetic resonance imaging (MRI) is a new medical imaging technology based on the principle of nuclear magnetic resonance, which has excellent diagnostic function for brain, thyroid, liver, gallbladder, spleen, kidney, pancreas, adrenal gland, uterus, ovary, prostate and other solid organs, as well as heart and great blood vessels.

Compared with other auxiliary examination methods, nuclear magnetic resonance has the advantages of more imaging parameters, faster scanning speed, higher tissue resolution and clearer images, which can help doctors "see" early lesions that are not easy to detect. At present, it has become a sharp weapon for early screening of tumors, heart diseases and cerebrovascular diseases.

It is understood that because metals can interfere with external magnetic fields, patients must remove all metal objects from their bodies before undergoing MRI examination. Do not wear watches, metal necklaces, dentures, metal buttons, metal contraceptive rings and other magnetic objects for MRI examination.

In addition, wearing a pacemaker and having paramagnetic metal implants in the body, such as metal clips, stents, steel plates, screws, etc., can not be examined by magnetic resonance imaging. Upper abdomen (such as liver, pancreas, kidney, adrenal gland, etc.). Be sure to check on an empty stomach, but you can drink enough water before the check, which is conducive to a clearer boundary between the stomach and the liver and spleen.

Found a tumor

Nuclear magnetic resonance (MRI) is the most effective imaging diagnostic method for diseases such as brain and spinal cord. It can not only detect tumor, cerebral infarction, cerebral hemorrhage, brain abscess, cerebral cysticercosis and congenital cerebral vascular malformation at an early stage, but also determine the type and cause of hydrocephalus. For breast cancer, the first major gynecological disease that harms women's life and health in China, accurate screening through MRI is helpful to find the early focus of breast cancer.

For people with "hypertension, hyperlipidemia and hyperglycemia", we can detect high-risk diseases such as heart disease and cerebral infarction at an early stage through magnetic resonance examination of the head and heart before the health has issued a red light warning.

In addition, MRI can also be used to examine abdomen and pelvic cavity, such as liver, gallbladder, pancreas and uterus. Imaging of abdominal great vessels and blood vessels of limbs can definitely diagnose true and false aneurysms, dissecting aneurysms and various lesions of blood vessels of limbs. Nuclear magnetic resonance (NMR) is very accurate in the diagnosis of various joint tissue diseases and very sensitive to aseptic necrosis of bone marrow and bone.

It is understood that the Medical Imaging Department of Peking University Shenzhen Hospital is a key medical specialty in Shenzhen and a key clinical medical imaging specialty in Guangdong Province. At present, the Medical Imaging Department of our hospital has three world-advanced magnetic resonance (MR) scanners, namely 1 3.0T MRI scanner and two 1.5T MRI scanners. In view of the limitation of inaccurate ultrasound positioning, virtual prostate biopsy is currently used for early diagnosis and differential diagnosis of prostate cancer.

Baidu encyclopedia-nuclear magnetic resonance

Baidu encyclopedia-nuclear magnetic resonance