Transcranial Doppler Ultrasound and Magnetic Resonance Imaging (MRI) each have their own characteristics. Transcranial Doppler Ultrasound is a test that looks at blood flow in the brain, while MRI is a test that is used to clearly visualize the presence of parenchymal lesions in various areas of the brain, and it is not possible to evaluate which one is better. Transcranial Doppler ultrasonography is a noninvasive test that examines hemodynamic changes in the main stem of the basilar artery and is one of the common tests performed in neurology. This test mainly observes whether there is any significant narrowing of the main arterial vessels in the patient’s brain, but it cannot show changes in the specific structures of the brain. MRI can clearly show lesions in the cerebral hemispheres, spinal cord, and brain stem, and is useful in aiding the diagnosis of acute cerebral infarction, cerebral hemorrhage, and brain tumors. However, MRI angiography can also look at arterial stenosis in the brain. The specific tests should be performed under the advice of a neurologist.