I. Recommended points for CT diagnosis of brain imaging technology
1.CT is the first choice of examination for brain hemorrhage. (Grade A evidence, Grade I recommendation)
2.CT is the preferred diagnostic test for arachnoid hemorrhage. (Grade A evidence, Grade I recommendation)
3.CT is the first choice of emergency examination for acute ischemic stroke. (Class A evidence, Level I recommendation)
4. NECT should be completed to rule out cerebral hemorrhage and to clarify the presence of hypointense ischemic foci before intravenous rtPA treatment. (Grade A evidence, Grade I recommendation)
5, CT can be used as the initial routine examination of cerebral venous sinus thrombosis; if unexplained edema or cerebral hemorrhage in the cerebral cortex and subcortical areas is found, the possibility of thrombosis should be considered, but at this time, due to the low sensitivity and false-positive rate of CT, it is not recommended as the first choice. (Level B evidence, Level II recommendation)
Second, the recommended points of brain imaging technology MRI
1. Diffusion-weighted imaging (DWI) has better sensitivity and specificity than CT and other MRI modalities within 6 hours of the onset of stroke symptoms, and is useful for early ischemic stroke diagnosis. (Level A evidence, Level I recommendation)
2. If the patient has symptoms for more than 3 hours, it is recommended to improve MRI-DWI or CTA-SI, angiography and perfusion imaging, which is especially important for patients with arterial thrombolysis or thrombus retrieval. (Level A evidence, Level I recommendation)
3. DWI can assess the severity and final infarct size of anterior cerebral stroke (level B evidence, level II recommendation), but it is not recommended in the basal region (level C evidence).
4. MRI-DWI is useful for predicting the size of the final infarct area (level B evidence, level II recommendation) and clinical prognosis (level C evidence, level II recommendation).
5. MRI is significantly better than CT for the subacute and chronic phases of stroke and post-ischemic hemorrhage.(Level B evidence, Level II recommendation)
6.GRE sequence of MRI can diagnose cerebral hemorrhage at an early stage, and it is significantly better than CT in diagnosing new or old microhemorrhagic foci.(Grade B evidence, Grade II recommendation)
7.For microhemorrhagic foci detected by MRI but not shown by CT, it is currently not a contraindication to intravenous thrombolysis. (Grade B evidence, Grade II recommendation)
III. Recommended points of cerebrovascular imaging techniques
1. CTA has high sensitivity and specificity in the diagnosis of aneurysm and can be the first choice for patients who have not received DSA. (Level B evidence, level II recommendation)
2, CTA is the examination of choice for spontaneous arachnoid hemorrhage caused by intracranial aneurysm, and CT perfusion imaging (CTP) has diagnostic value for delayed hemorrhage. (Grade B evidence, Grade II recommendation)
3.For patients with CTA-negative subarachnoid hemorrhage, it is recommended to refine DSA.(Level B evidence, Level II recommendation)
4.CE-MRA is suitable for non-invasive screening of arterial entrapment. (Level A evidence, Level I recommendation)
5.In the diagnosis of cerebral venous sinus thrombosis, MRI and MRV are the primary examination modalities that are accurate and sensitive at present, and also the main examination modalities for follow-up. However, for patients with venous thrombosis alone and without intraventricular thrombotic imaging changes, further DSA examination is still required. (Grade A evidence, Grade I recommendation)
6, DSA is the gold standard for cerebral venous sinus thrombosis and can be used as a complementary means to MRI and MRV. (Grade A evidence, Grade I recommendation)
7.DSA is the gold standard for the diagnosis of intracranial aneurysm and is the primary recommendation. (Grade A evidence, Grade I recommendation)
8.DSA is the gold standard for the diagnosis of intracranial artery stenosis. (Class A evidence, Class I recommendation)
IV. Key points of technical guidelines for cerebral perfusion imaging
1.CTP combined with CTA testing can assess stenosis and predict TIA risk classification based on data such as TTP delay. (Grade B evidence, Grade II recommendation)
2, CTP can assist in evaluating peripheral hematoma perfusion. (Grade B evidence, Grade II recommendation)
3, CTP can diagnose delayed hemorrhage in patients with subarachnoid hemorrhage. (Grade B evidence, Grade II recommendation)
4, CTP can assist in clinical differentiation between permanent infarction and the presence of reversible ischemic semidark zones, which can help in thrombolysis and prognostic judgment. (Level B evidence, level II recommendation)
5.MRP is slightly better than CTP in identifying the perfusion area and ischemic semidark zone area, which helps to expand the thrombolytic time window. (Grade B evidence, Grade II recommendation)
6.MRP can assist in the differential diagnosis of TIA and mini-stroke. (Level B evidence, level II recommendation)
V. Other technical recommendations
1. Diffusion tensor imaging (DTI) can help to determine the degree of neurodegeneration and predict the regression of motor function. (Level B evidence, level II recommendation)
2. BOLD sequence can assess neurovascular activity, as well as the activity of cerebral infarction lesions. (Level B evidence, Level II recommendation)
3. Magnetic resonance elastography (MRE) can differentially diagnose stroke and brain tumor. (Level C evidence, Level III recommendation)
4.Magnetic resonance spectroscopy (MRS) can be used for early evaluation of metabolic changes in ischemic brain tissue, severity of ischemic tissue damage, and to determine patient prognosis and outcome. (Level C evidence)
5. Magnetic susceptibility weighted imaging (SWI) can provide early diagnosis of cerebral hemorrhage, ischemic stroke hemorrhagic transformation, microhemorrhage and venous thrombosis, thus providing information on ischemic stroke hemodynamics. (Level B evidence, Level II recommendation)