Role of Chemical Exchange Saturation Transfer andMagnetization Transfer MRI in Detecting Metabolicand Structural Changes of Renal Fibrosis in an AnimalModel at 3T

ABSTRACT

Objective@#To investigate the value of combined chemical exchange saturation transfer (CEST) and conventional magnetizationtransfer imaging (MT) in detecting metabolic and structural changes of renal fibrosis in rats with unilateral ureteral obstruction(UUO) at 3T MRI. @*Materials and Methods@#Thirty-five Sprague-Dawley rats underwent UUO surgery (n = 25) or sham surgery (n = 10). Theobstructed and contralateral kidneys were evaluated on days 1, 3, 5, and 7 after surgery. After CEST and MT examinations,18F-labeled fluoro-2-deoxyglucose positron emission tomography was performed to quantify glucose metabolism. Fibrosis wasmeasured by histology and western blots. Correlations were compared between asymmetrical magnetization transfer ratio at1.2 ppm (MTRasym(1.2ppm)) derived from CEST and maximum standard uptake value (SUVmax) and between magnetization transferratio (MTR) derived from MT and alpha-smooth muscle actin (α-SMA). @*Results@#On days 3 and 7, MTRasym(1.2ppm) and MTR of UUO renal cortex and medulla were significantly different from those ofcontralateral kidneys (p < 0.05). On day 7, MTRasym(1.2ppm) and MTR of UUO renal cortex and medulla were significantly differentfrom those of sham-operated kidneys (p < 0.05). The MTRasym(1.2ppm) of UUO renal medulla was fairly negatively correlated withSUVmax (r = -0.350, p = 0.021), whereas MTR of UUO renal medulla was strongly negatively correlated with α-SMA (r = -0.744, p <0.001). @*Conclusion@#CEST and MT could provide metabolic and structural information for comprehensive assessment of renal fibrosisin UUO rats in 3T MRI and may aid in clinical monitoring of renal fibrosis in patients with chronic kidney disease.