There are some people who visit the doctor because of drowsiness as the first symptom before discovering lung cancer brain metastasis, so it is a sign of advanced lung cancer. It should also be excluded that advanced lung cancer is combined with chronic obstructive pulmonary disease and liver disease, and drowsiness caused by pulmonary encephalopathy and hepatic encephalopathy due to respiratory failure and liver failure, which is not a sign of advanced lung cancer. Multiple brain metastases are more common in advanced lung cancer. The diagnosis rate of multiple brain metastases accounts for more than 50% when diagnosing brain metastases by CT examination, and the diagnosis transfer rate of multiple brain metastases by MRI reaches 2/3-3/4, indicating that MRI can detect smaller lesions more accurately and earlier.