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Quantitative MR Images of Renal Parenchymal Disease: An Experimental In Vivo Study Using Rat Chronic Kidney Disease Models1Radiology, Seoul National University Hospital, Seoul, Korea, Republic of
Synopsis
Keywords: Kidney, Quantitative Imaging
Quantitative MRI sequences could be a noninvasive assessment modality in the diagnosis and evaluation of CKD. In particular, T1ρ may be a suitable MR sequence parameter to assess renal parenchymal fibrosis in a quantitative manner. Moreover, monitoring the change in common metabolites using MRS may reflect the alteration of osmolality in the renal medulla in CKD.This study aimed to validate the usefulness of quantitative multiparametric magnetic resonance imaging (MRI) sequence parameters and suggest suitable spectroscopic metabolites in the evaluation of parenchymal fibrosis using an experimental animal model of chronic kidney disease (CKD) by long-term adenine intake.
Materials and Methods
Experimental adenine intake in rats induces renal dysfunction due to the deposition of 2,8-dihydroxyadenine crystals in the renal parenchyma. This pathophysiologic progression resembles that of human CKD. A total of 16 male Wistar rats were analyzed. They were divided into three groups: control (n = 7), CKD1 (n = 5), and CKD2 (n = 4). The CKD groups were kept under the 3- or 6-week term intake of 0.25% adenine. According to the group assignment, quantitative MRI sequences, including diffusion-weighted image, T1ρ (T1 rho), T2* mapping, and in vivo MR spectroscopy (1H-MRS), were performed using a 9.4T animal MR scanner. A semiquantitative histopathologic analysis for renal fibrosis was conducted. Comparative analyses of quantitative MR values measured from anatomic regions of kidneys between groups were performed.
Results
Compared to the control group, significant histopathologic changes were observed in CKD groups according to periods. The apparent diffusion coefficient (ADC) and T1 (T1 rho) values were significantly increased in all CKD groups compared with those in the control group. The differences in values measured from the cortex and outer medulla were significant between the CKD and control groups. The total ADC values tended to increase according to periods. The T1ρ (T1 rho) values were increased in the CKD1 group and decreased in the CKD2 group. Among MRS metabolites acquired from each region, the ratio of glycerophosphorylcholine–choline–phosphatidylcholine signals to myo-inositol–glycine signals collected from voxels located at medulla region was significantly lower in the CKD groups than in the control group (0.17 vs. 0.456, P = 0.0448).
Conclusion
Quantitative MRI sequences could be a noninvasive assessment modality in the diagnosis and evaluation of CKD. In particular, T1ρ may be a suitable MR sequence parameter to assess renal parenchymal fibrosis in a quantitative manner. Moreover, monitoring the change in common metabolites using MRS may reflect the alteration of osmolality in the renal medulla in CKD.
Acknowledgements
No acknowledgement found.References
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