I. Conventional clinical applications
MRI has the best effect on the central nervous system because its multi-directional, multi-parameter, multi-axis tilt cut layer is extremely superior for the localization and qualitative diagnosis of central nervous system lesions. In the diagnosis of central nervous system diseases, except for skull fracture and acute intracranial hemorrhage, which are inferior to CT, MRI is superior to CT in the diagnosis of brain tumors, intracranial infections, cerebral vascular lesions, cerebral white matter lesions, cerebral developmental malformations, degenerative brain lesions, ventricular and subarachnoid lesions, cerebral contusions, subacute intracranial hematomas, and tumors, infections, vascular lesions and traumatic lesions of the spinal cord.
2, craniocervical metastases: Because MRI has the advantage of not producing bone artifacts, it has unique advantages in the diagnosis of lesions in the posterior cranial recess and craniocervical junction area.
3.Cervical lesions: Because of the high soft tissue resolution and vascular flow effect, MRI can clearly show the pharynx, larynx, thyroid, cervical lymph nodes, blood vessels and cervical muscles, which has important diagnostic value for the diagnosis of cervical lesions.
MRI has special value for the diagnosis of mediastinal and hilar lymph node enlargement and occupying lesions. However, the detection of intrapulmonary calcifications and small lesions in the lung parenchyma and interstitium is far inferior to that of CT.
5.Cardiac macrovascular lesions: Since the heart has the characteristics of periodic beating, the use of cardiac gating trigger technology can make accurate diagnosis of myocardial and pericardial lesions and certain congenital heart diseases.
6.Liver lesions: Multi-parametric techniques have important value in the differential diagnosis of liver lesions. Rapid sequences and dynamic enhancement, diffusion and perfusion imaging through Tl-weighted images and T2-weighted images can identify liver cysts, cavernous hemangiomas, hepatocellular carcinoma and metastatic carcinoma. in phaseout phase techniques are not as sensitive as CT and ultrasound, but have high specificity. MRCP combined with conventional and dynamic enhanced MRI is of great value for the localization and qualitative diagnosis of gallbladder and biliary tract diseases.
7. Kidney and ureteral lesions: The kidney and its surrounding fatty sac form a sharp contrast on MR images, and the renal parenchyma contrasts well with the urine in the renal pelvis. MRI has an important value in the diagnosis of renal diseases. MRI can directly display the urographic image (MRU), which has an important diagnostic value for ureteral stenosis and obstruction.
8, pancreatic lesions: due to the fat lining around the pancreas, MRI can show the pancreas and pancreatic ducts, MRCP is helpful for pancreatic diseases, and in the diagnosis of pancreatic lesions, CT and MRI are both complementary.
9, pelvic lesions: MRI multi-directional, large field of view imaging can clearly show the anatomical structure of the pelvis. It is the best imaging tool for pelvic tumors, inflammation, endometriosis, metastatic cancer, prostate cancer and other lesions.
MRI can clearly show cartilage, joint capsule, joint fluid and joint ligament, which has unparalleled value for the diagnosis of articular cartilage damage and joint effusion. In the diagnosis of degeneration and necrosis of articular cartilage, it is earlier than other imaging methods.
II. Advanced clinical and scientific applications
1.Central nervous system
(1) Vascular lesions: display and assessment of hyperacute and acute cerebral infarction, diffusion images with different B values, assessment of diffusion and perfusion combined with semidark band to guide early thrombolytic therapy, dynamic changes of NAA and Lac peak in MRS over time. Diagnostic value and evaluation of 3D-TOF, 3D-PC MRA and CE-MRA of cerebrovascular malformations.
(2) Traumatic diseases: comprehensive dynamic evaluation of diffuse axonal injury with diffusion, MRS and various conventional imaging sequences and prediction of prognosis. sensitivity of T2Tirm sequence for small amount of epidural and subdural hemorrhage, small amount of subarachnoid hemorrhage display, sensitivity of GRE T2* image for brain contusion, diffuse axonal injury and small amount of intracerebral hemorrhage display.
(3) Neoplastic lesions: diffusion imaging ADC for the diagnosis and differential diagnosis of intra- and extracerebral tumors, differences in metabolites of different types of tumors by MRS, tumor grading studies by MRS and Perfusion or a combination of both, preoperative localization of tumors near motor function areas, motor language function areas, and visual cortex areas by fMRI, preoperative localization of tumors by MRS, dynamic enhancement, Perfusion or a combination of all three. (4) Infectious lesions.
(4) Infectious lesions: Diagnosis and differential diagnosis of brain abscess by enhancement, MRS and Diffusion, and study and analysis of intracranial infection secondary to HIV by MRS and Diffusion.
(5) Congenital lesions: MRS and Diffusion can provide more information for diagnosis and differential diagnosis.
(6) Degenerative and metabolic lesions: measurement of hippocampal volume in epileptic patients, changes in local metabolites of MRS, enhanced scans of multiple sclerosis, changes in MRS, ADC values. Changes in signal in the basal ganglia region of images of hepatic encephalopathy and MRS.
(7) Neonatal ischemic-hypoxic encephalopathy: MRS, diffusion provides more information on its neuropathophysiological changes, neuropathology, and prognosis judgment.
(8) FMRI on learning and memory of different languages, brain cognitive function, stimulation of various sensory stimuli of different intensities, stimulation of different forms of nociception on the localization of brain activation zones, the scope and distribution of brain activation zones of different acupuncture points and different frequencies of acupuncture.
(9) Spinal cord lesions: diffusion ADC values to diagnose early spinal cord lesions.
(10) Application of enhancement: meningeal lesions, suspected metastases should be enhanced and the double dose should be used, suspected pituitary microadenoma should be examined by dynamic enhancement, MS (multiple sclerosis) in the brain and spinal cord should be examined by enhancement.
2.Head and neck
(1) Orbital lesions: 3D-FSPGR sequence + fat suppression technique is applied in the diagnosis and differential diagnosis of intraorbital lesions to improve the lesion diagnosis rate.
(2) Evaluation of neurovascular relationship of skull base: 3-D Fiesta sequence combined with enhanced FSPGR sequence for the display of vestibular nerve, cochlear nerve and facial nerve, TOF-FSPGR sequence for the display of vascular and nerve relationship.
(3) Maxillofacial joint:: TMJ conventional MRI orientation is tilted coronal and tilted sagittal. Sagittal monolayer multi-temporal dynamic imaging can be used to diagnose meniscal lesions and their functional lesions in cine display mode, which can replace temporomandibular arthrography.
(4) Nasopharynx: Enhancement to determine the size, extent and depth of infiltration of nasopharyngeal carcinoma; to show the invasion and metastasis of the skull base; dynamic enhancement is used to identify recurrence of nasopharyngeal carcinoma after treatment and fibrosis after radiotherapy, MRS, perfusion and diffusion can provide more information for diagnosis and differential diagnosis of recurrence.
(5) Neck: MRI study of carotid atherosclerotic plaque.
(6) Display and determination of airway stenosis sites in sleep apnea syndrome, quantitative measurement of airway volume before and after treatment.
(7) Magnetic resonance spectroscopy studies of tumors of the neck and sinuses.
3.Spine
Enhanced MRI + fat suppression technique to differentiate postoperative epidural fibrosis from non-enhanced recurrent or residual disc hernias, and to provide assistance in the diagnosis of primary epidural tumors and metastases.
4.Thorax
(1) Thoracic and mediastinal tumors: Fiesta or Fastcine sequences provide more definitive information for the diagnosis and staging of mediastinal tumors and central type lung cancer.
(2) Breast masses: Dynamic enhancement, diffusion ADC values, MRS combined with conventional MR imaging can basically clarify the diagnosis of benign and malignant breast masses, staging of breast cancer and preoperative evaluation.
5.Heart
(1) Cardiac morphology: the diagnosis of cardiomyopathy by black blood (Double-IR, Triple-IR) and bright blood (Fista, Fastcine) techniques, and the diagnosis of valvular and outflow tract lesions.
(2) Evaluation of myocardial activity in coronary artery disease: myocardial perfusion (at rest, under load), survival of delayed enhanced judgment myocardium, guiding the determination of treatment plan and assessment of treatment effect.
6.Abdomen
(1) Liver nodal lesions: dynamic enhancement scanning and perfusion imaging, diffusion ADC values, EPI sequences and liver-specific contrast agents such as FELIMAG are used to improve the sensitivity and specificity of diagnosis, which helps to identify benign and malignant intrahepatic occlusive lesions, detect smaller occult lesions, resectability of hepatocellular carcinoma and determine the prognosis.
(2) Evaluation of the arterial system, portal venous system, hepatic venous system and biliary system before and after liver transplantation.
(3) Biliary system: MRCP can show the normal biliary system and its variants, and combined with conventional and dynamic MRI, it can make accurate localization and more accurate qualitative diagnosis of benign and malignant obstruction of the biliary system.
(4) Pancreas: The combination of dynamic enhancement imaging with fat suppression and MRCP can provide more help in the display and differentiation of inflammatory diseases and tumors of the pancreas.
(5) Small intestine lesions with water and gas imaging + enhancement have high diagnostic sensitivity.
(6) Kidney: Dynamic MR enhancement plus fat suppression can accurately identify the location of mass lesions as intrarenal, extrarenal or retroperitoneal. The evaluation of perinephric and vascular involvement in kidney cancer staging is better than CT, and the change of renal cortex and medullary signal over time in dynamic MR scan can evaluate the situation of renal function.
(7) Adrenal gland: magnetic resonance duplex scanning and dynamic MR enhancement examination can differentiate most adrenal tumors, malignant tumors and pheochromocytoma.
(8) Prostate cancer: Prostate imaging with a dedicated phased array coil in the abdomen or pelvis + endorectal coil has high diagnostic sensitivity and specificity for prostate cancer.
7.Musculoskeletal system
(1) Articular cartilage: T2* + fat suppression technique, FSPGR + fat suppression technique, proton density imaging + fat suppression technique several techniques for cartilage display evaluation.
(2) Rheumatoid arthritis: combination of dynamic enhancement and cartilage display techniques for early diagnosis and clinical study of pathological changes.
(3) Study of fatigue fracture magnetic resonance.
(4) MR enhancement examination is nearly as sensitive as nuclear scan for bone metastasis and more specific than ECT, which can distinguish tumor, aseptic necrosis and parasympathetic dystrophy bone changes, can roughly distinguish the histological type of bone tumor, and can distinguish post-treatment (radiotherapy or chemotherapy) changes from tumor recurrence.
(5) Imaging of the sacroiliac joint in ankylosing spondylitis.
(6) Tear of rotator cuff, shoulder joint crush syndrome.
(7) The study of signal changes before and after treatment of bone marrow tumor.
8.Psychiatric diseases
(1) Mania, schizophrenia: MRS of the limbic system.
(2) Quantitative measurement of certain limbic systems in depression, preliminary application of MRS
(3) Vascular dementia, Alzheimer’s disease: quantitative measurement of the volume of the limbic system, MRS in multiple parts of brain tissue.
9.MRA and CE-MRA
(1) 2D-TOF-MRA for venous vascular imaging of sagittal and sigmoid sinuses, 3D-TOF, 3D-PC neurovascular lesions can be used to show aneurysms, vascular stenosis and occlusion, arterial- venous malformations and their blood supplying arteries and draining veins.
(2) CE-MRA can be used in the nervous system, skeletal muscular system, abdomen and other organs to show the blood supply of tumor vessels and images of tumor compression and displacement of adjacent vascular structures, providing more information for the development of surgical plans.
(3) CE-MRA is of great clinical application value in the areas of entrapment aneurysm, renal artery stenosis, spinal vascular malformation, extensive vascular lesions in the lower extremities, portal vascular imaging, etc., and is extremely cost-effective.
10.Magnetic resonance water imaging technology
It includes magnetic resonance cholangiopancreatography (MRCP), magnetic resonance urologic imaging (MRU), magnetic resonance spinal canal imaging (MRM), magnetic resonance inner ear imaging, magnetic resonance salivary ductography, magnetic resonance tear ductography, magnetic resonance ventricular systemography, etc. Magnetic resonance aqueous imaging technology, as a safe, contrast-free and non-invasive imaging means, replaces to some extent the traditional imaging means such as diagnostic ERCP, PTC, IVP, X vertebral ductography, X salivary ductography, and lacrimal ductography.
(1) Magnetic resonance cerebrospinal fluid imaging: display of the normal ventricular system, narrowing of the conduit, and obstructive lesions.
(2) MR nasolacrimal ductography: nasolacrimal duct occlusion mostly occurs proximally, and MR nasolacrimal ductography can show dilatation and narrowing of the lacrimal sac as well as filling defects in the nasolacrimal duct, the latter mostly due to tumors.
(3) MR inner ear labyrinthography: congenital anomalies of the inner ear, vestibular duct syndrome, cochlear duct dilatation, labyrinthitis, and cochlear implantation to rule out surgical contraindications and relative contraindications.
(4) MR salivary ductography: evaluation of salivary duct dilatation, salivary duct stenosis, traumatic salivary duct injury, and x-ray-transparent calculi. In addition, in combination with conventional serial MR imaging, complete evaluation of salivary gland parenchyma and salivary ducts is possible.
(5) Magnetic resonance cholangiopancreatography (MRCP): to show normal pancreaticobiliary duct structure and its variants; to show cholelithiasis, benign and malignant bile duct obstruction; acute and chronic pancreatitis, pancreatic detachment.
(6) Magnetic resonance spinal canalography: MRM can show the spatial relationship between the intervertebral disc or the bony flap and the nerve root sheath membrane and the caudal filament, and at the same time, it can provide a kind of line drawing for the surgeon.
(7) MRI urinary tract water imaging technique: It has an extremely high display rate for urinary tract obstruction and an excellent display of ureteral, pelvic and bladder stones and benign and malignant ureteral strictures. It can also show the renal parenchyma and urinary collecting system at the same time, and is mainly used for the diagnosis of urinary tract hydrops.