Preparation of patients before being examined
1.Inquire and check if the patient has a pacemaker, nerve stimulator, artificial heart valve, eye foreign body and aneurysm clip, do not conduct the examination if you find these items;
2. Remove all metal objects from the patient’s body before entering the examination room, such as dentures, hairpins, fingers, earrings, keys, pens, watches, coins, etc. These objects can cause metal artifacts and affect the imaging quality. Credit cards, disks, and magnetic tapes should also be removed, otherwise demagnetization damage can occur. Before examining the eyes, eye shadow and other cosmetics should be washed off, and the pelvis should be examined by removing women’s sanitary napkins and contraceptive rings, otherwise artifacts will also affect the diagnosis;
3, young children, irritable and claustrophobic patients should be given appropriate amounts of sedatives, such as chloral hydrate, Valium, etc.
4, stroke, brain tumor with cranial hypertension should first take measures to lower the pressure, otherwise the patient lying supine will cause asphyxia and aspiration pneumonia due to jet vomiting.
Contraindications of magnetic resonance examination
1.People with pacemakers and neurostimulators;
2.Patients who have undergone aneurysm surgery and intracranial aneurysm clips;
3.Has had heart surgery. With artificial heart valves;
4.Patients with metal foreign bodies in the eye or various metal implants in the body;
5, women during pregnancy;
6, critically ill patients who need to use life support systems;
7.Patients with epilepsy;
8.Patients with claustrophobia.
Magnetic resonance examination indications
1, central nervous system lesions: the central nervous system location is fixed, not affected by respiratory movement, gastrointestinal peristalsis, so MRI is the best effect of the central nervous system, MRI’s multi-directional, multi-parameter, multi-axis tilt layer for the localization of central nervous system lesions qualitative diagnosis is extremely superior.
In the diagnosis of CNS diseases, MRI is superior to other imaging examinations in the diagnosis of brain tumors, intracranial infections, cerebral vascular lesions, cerebral white matter lesions, cerebral developmental malformations, degenerative brain lesions, ventricular and subpyramidal lesions, cerebral contusions, subacute intracranial hematomas, and tumors, infections, vascular lesions, and traumatic injuries of the spinal cord, except for skull fractures and acute intracranial hemorrhage, which are inferior to CT. Because MRI has the advantage of not producing bone artifacts, it has unique advantages for the diagnosis of lesions in the posterior cranial recess and craniocervical junction area.
2. Eye, nose, mouth and larynx lesions: including congenital lesions, occupational lesions, inflammation, trauma and temporomandibular joint lesions, etc.
3, spinal lesions: including cervical, thoracic and lumbar intraspinal occupying lesions, spinal cord inflammation, degeneration, cavitation and traumatic lesions, intervertebral discs, ligaments and paravertebral soft tissue lesions, etc.
4, lung and mediastinal lesions: including benign and malignant occupying lesions of the lung and mediastinum, inflammation, traumatic lesions, etc. These include pericardial and myocardial lesions, intra-cardiac occupying lesions and large vessel abnormalities. MRI is particularly valuable in the diagnosis of mediastinal and hilar lymph node enlargement and occupying lesions due to the flow-space effect of the vessels in the mediastinum and the high signal characteristics of the fat in the mediastinum, which creates excellent contrast in mediastinal MR images. However, the detection of intrapulmonary calcifications and small lesions is inferior to that of CT.
5. Upper abdomen and retroperitoneal lesions: including benign and malignant occupying lesions of the liver, spleen, pancreas, kidney, adrenal glands and other organs, abscesses, hematomas, trauma and congenital anomalous lesions. Multiparametric techniques are of great value in the differential diagnosis of liver lesions, and can directly identify liver cysts, cavernous hemangiomas, hepatocellular carcinoma and metastatic carcinoma by T1-weighted images and T2-weighted images without contrast agents. The diagnosis of fatty liver is less sensitive than CT, and MRCP (bile duct water imaging) is of great value in the diagnosis of gallbladder and biliary tract diseases.
The kidney and its surrounding fatty capsule form a sharp contrast on MR images, and the renal parenchyma contrasts well with the urine in the renal pelvis. MRI is of great value in the diagnosis of renal diseases, and MRI can directly display urographic images (MRU), which is of great value in ureteral stenosis and obstruction. Due to the fat lining around the pancreas, MRI can show the pancreas and pancreatic ducts, and MRCP is helpful for pancreatic diseases. In the diagnosis of pancreatic lesions, CT and MRI are both complementary.
MRI can clearly show the anatomical structure of the pelvis with multi-directional and large field imaging. It has important diagnostic value especially for female pelvic diseases, and it is easier to identify blood vessels and lymph nodes in the pelvis, and it is the best imaging means for pelvic tumors, inflammation, endometriosis, metastatic cancer and other lesions.
7, bone and joint lesions: including benign and malignant tumors: chronic inflammation, bursal effusion, chronic injury, aseptic necrosis, etc. MRI can clearly display cartilage, joint capsule, joint fluid and joint ligament, and has unparalleled value for the diagnosis of articular cartilage injury, joint effusion and other lesions by other imaging examinations. In the diagnosis of degeneration and necrosis of articular cartilage, it is earlier than other imaging methods. Such as aseptic necrosis of the femoral head, meniscal injury.
8, soft tissue lesions: benign and malignant tumors, chronic injuries, inflammation, etc.
9, vascular lesions: including systemic vascular motility and static tumors, vascular stenosis, occlusion, congenital variants, etc.