Primary study of chronic kidney disease with intravoxel incoherent motion diffusion-weighted imaging

Abstract

Objective To investigate the value of intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) in the staging of chronic kidney disease(CKD). Methods From May 2016 to April 2017, seventy-two patients diagnosed as CKD according to the criteria of clinical diagnostic and 20 healthy volunteers (control group) underwent routine MRI and IVIM-DWI (8 b values, 0 to 800 s/mm2).CKD patients were divided into two groups based on their estimated glomerular filtration rate (eGFR): mild CKD group (45 cases, eGFR≥60 ml·min-1·1.73m-2) and moderate to severe CKD group (27 cases, eGFR<60 ml·min-1·1.73 m-2). The ADC, true diffusion coefficient (D), pseudo-diffusion coefficient (D*), perfusion fraction (f) were measured on both cortex and medulla. The paired-samples t test was used to compare the cortico-medullary difference of the ADC, D, D* and f values in three groups. Differences of the ADC, D, D* and f values among three groups were compared using the one-way analysis of variance (ANOVA). Correlations between eGFR and the IVIM-DWI parameters in CKD were evaluated by using Pearson correlation analysis. ROC was performed to evaluate the diagnostic efficiency of using IVIM-DWI parameters to distinguish CKD with moderate to severe renal impairment from mild renal impairment, as well as distinguish CKD with mild renal impairment from healthy volunteers. Results The cortical ADC,D,D* and f values were significantly higher than that in the medulla in healthy volunteers(all P<0.05). The cortical ADC,D* and f values were significantly higher than that in the medulla in mild CKD group (all P<0.05). The cortical ADC,D and f values were significantly higher than that in the medulla in moderate to severe CKD group (all P<0.05). The ADC,D,D* and f values of cortex and medulla showed significantly differences among three groups (all P<0.05). In CKD patients, no significant correlation was found between medullary D*,f values and eGFR, there was a significant positive correlation between eGFR and cortical ADC,D,D* and f values (r=0.475, 0.362, 0.625, 0.276;all P<0.05) ,as well as between eGFR and medullary ADC,D values (r=0.427, 0.615;P<0.05). The results of the ROC analysis for distinguishing the mild CKD group from the moderate to severe CKD group revealed that the cortical D* value had the highest area under the ROC curve (AUC=0.965), cortical f value showed high sensitivity(92.6%) to distinguish CKD with different degree of renal impairment, with the threshold of 32.99%, and cortical D* value showed high specificity (97.8%) with the threshold of 17.07×10-3 mm2/s;the results of the ROC analysis for distinguishing the mild CKD group from healthy volunteers revealed that the cortical D* value had the highest AUC (0.885), medullary ADC value showed high sensitivity (82.2%) to distinguish mild CKD group from healthy volunteers, with the threshold of 1.83×10-3 mm2/s, and medullary f value showed high specificity(100.0%)with the threshold of 21.70%, as well as medullary D value showed high specificity (100.0%) with the threshold of 1.75×10-3mm2/s. Conclusion IVIM-DWI may be useful for CKD early diagnosis and assessing renal function. Key words: Kidney diseases; Intravoxel incoherent motion; Diffusion weighted imaging; Glomerular filtration rate