The T1T2 signal of MRI reflects the difference in relaxation time between tissues to suggest the composition of that normal or diseased tissue. The principle of nuclear magnetic resonance (MRI) is to use a strong external magnetic field to produce resonance phenomenon on the role of hydrogen nuclei in human tissues for imaging, and the time for the hydrogen atoms to return to the equilibrium state after resonance is called the relaxation time. The longitudinal relaxation time is T1, and the transverse relaxation time is T2, reflecting the difference in T1 values between tissues as T1-weighted imaging (T1WI), and the difference in T2 values between tissues as T2-weighted imaging (T2WI). T1WI and T2WI indicate the length of relaxation time in black and white grayscale. White shadows are high signal, gray shadows are medium signal, and black shadows are low or no signal.The high signal on T1WI images represents tissues with short T1 relaxation times, whereas the high signal on T2WI images represents tissues with long relaxation times. The signal level of T1 and T2 images can indicate the tissue composition or the composition of the lesion, e.g., cerebrospinal fluid is a low-signal black shadow in T1 and a high-signal white shadow in T2, while adipose tissue is a high-signal white shadow in T1 and a higher-signal white-gray shadow in T2. The reading of MRI should be combined with the T1T2 signal level, the shape, boundary and size of the lesion, etc. It is recommended that the patient consults the specialist in time and follows the doctor’s instructions for further examination and treatment.