Abstract: Ｏｂｊｅｃｔｉｖｅ：We aimed to explore whether the functional magnetic resonance imaging（fMRI），an noninvasive technique，could judge the nature of kidney lesions and predict recovery of kidney function in acute kidney injury （AKI） patients.
Ｍｅｔｈｏｄｏｌｏｇｙ：13 AKI patients who underwent fMRI and renal biopsy in the National Clinical Research Center of Kidney Diseases were enrolled in this study. The routine pathological data，including immunofluorescence，light microscopy，and electron microscopy，and pathology diagnoses were collected for each patient. Apparent diffusion coefficient of intravoxel incoherent motion diffusion weighted imaging（IVIM Standard-ADC） and magnetic resonance elastography （MRE）-derived stiffness，as well as baseline estimated glomerular filtration rate （eGFR） and follow-up data within 12 months after discharge were recorded for each patient. The relationship between IVIM Standard-ADC and MRE-derived stiffness and the rate of eGFR change during the follow-up period was analyzed.
Ｒｅｓｕｌｔｓ：Of the 13 patients（8 males，5 females），the median age was 33 （21～44） years. Mean baseline eGFR was 31（16.5～43.5） mL／（min·1.73 m2），and mean annual eGFR slope was 12.29（4.42～25.66）.The results of histology shows that 7 cases had chronic lesions and 6 cases were simple AKI. First，the slope of eGFR change over the 12 months follow-up period was not significantly correlated with the values of IVIM Standard-ADC and 45 Hz MRE-derived stiffness，but was significantly positively correlated with 60 Hz MRE-derived stiffness （rs=0.709； P=0.022）. Moreover，increased kidney stiffness was associated with better prognosis in kidney function in AKI（regression r2=0.456； P=0.032）. Second，we can see the same result in 45 Hz MRE-derived stiffness，the value of 45 Hz MRE-derived stiffness also could be a predictor of annual eGFR slope （regression r2=0.44； P=0.036）. That is，MRE-derived stiffness can relatively distinguish kidney injury degree and different eGFR recovery slope.
Ｃｏｎｃｌｕｓｉｏｎ：The study indicates that MRE can predict the change of kidney function in the future in AKI patients as a powerful noninvasive tool. Compared with the pure AKI patients，kidney function in patients with AKI combined with CKD is difficult to completely return to normal，and the baseline MRE-derived stiffness of the two patients are significantly different.

Key words: functional magnetic resonance imaging, acute kidney injury, kidney function, prognosis, estimated glomerular filtration rate