IVIM Monitor The Progressive Changes In Contrast-Induced Acute Kidney Injury And Development Of A Preprocedure Nomogram For Predicting Contrast-induced Acute Kidney Injury

Chapter One[Objective]Contrast-induced acute kidney injury is a prevalent cause of renal failure,and the noninvasive tools to monitor its progress are lacking.We applied intravoxel incoherent motion(IVIM)DWI to measure the progressive changes in kidney diffusion and perfusion of CI-AKI.[Materials and Methods]Twenty-four rats received Iopromide(370 mg/ml,1600 mg iodine/kg)to induce CI-AKI.IVIM DWI was performed on rats(n = 6)at 24 h prior to and 12,24,48,72,96 h after the injection using a 3.0 T MRI scanner.The progressive changes in the diffusion(D)and perfusion parameters(D*and f)were studied in the cortex(CO),outer medulla(OM),and inner medulla(IM).For the histology group(n = 18),three rats were sacrificed at each time point.[Results]In the CO,D reduced progressively from 24 h to 48 h(P<0.001)and increased starting from 72 h(P<.001).However,D decreased untill to 72 h in the medulla(P<0.001)and increased starting from 96 h(P<0.001).D*decreased to the bottom at 24 h in the cortex and medullar(P =.037)and started to recover at 48 h(P= 0.007).f decreased in the cortex and medullar in an early stage(12 h)(P = 0.035)of CI-AKI and then ascended in the later stage(72 h)(P = 0.017).The H&E staining showed serial pathological change in different degree including tubule epithelial cells and glomerulus cells cloudy swelling,atrophy,even necrosis and interstitial vasodilator.[Conclusions]Our study demonstrates the feasibility of using IVIM DWI to monitor the progress of CI-AKI,implying that IVIM DWI is a useful biomarker in the staging of CI-AKI.Chapter Two[Objective]Develop a preprocedure nomogram for predicting contrast-induced acute kidney injury(CI-AKI)after coronary angiography(CAG)or percutaneous coronary intervention(PCI).[Materials and Methods]The institutional Ethics Research Committee approved the study,and the written informed consent was waived from all patients.This reprospectively designed observational study included consecutive patients who underwent coronary angiography(CAG)or percutaneous coronary intervention(PCI)between January 2015 and January 2017.We included patients aged ?18 years who had stayed in the hospital for 2-3 days after coronary angiography.Serum creatinine concentrations was measured in these patients at hospital admission before coronary angiography and on days 1,2,and 3 after procedure.The exclusions were identified according to the updated European Society of Urogenital Radiology Contrast Media Safety Committee guidelines.Our Institutional Review Board approved this retrospective study and waived the need to obtain informed consent from the patients.A total of 245 patients were included in this study.A total of 27 clinical characteristics were collected from PACS,including age,sex,diabetes mellitus(DM),years since DM,pre-existing hypertension,lactate dehydrogenase(LDH),high-sensitivity C-reactive protein(Hs-CRP),current drinking,years since drinking,current smoking,years since smoking,pre-existing chronic kidney disease(CKD),and so on.Subsequent analysis was performed using R version 3.2.3(R Foundation for Statistical Computing).We used least absolute shrinkage and selection operator(Lasso)method to select features that were most significant and then built a regression model including selected variates,and develop a preprocedure nomogram for predicting CI-AKI.The predictive accuracy of the risk model was assessed by discrimination measured by C-statistic and calibration evaluated by Hosmer-Lemeshow ?2 statistic.The differences in various variables between CI-AKI group and non-CI-AKI group were assessed by using an independent samples t test,Chi-square test,or Mann-Whitney U test,where appropriate.All statistical tests were two-sided,and p-values of<0.05 were considered significant.The CI-AKI risk score was calculated for each patient as a linear combination of selected predictors that were weighted by their respective coefficients.We divided patients into high-risk and low-risk groups according to cutoff value of CI-AKI risk score.[Results]A total of 245 patients were included in this study.The occurrence of CI-AKI was 13.9%(34 of 245).Ten predictors including sex,diabetes mellitus,lactate dehydrogenase level,C-reactive protein,years since drinking,chronic kidney disease(CKD),stage of CKD,stroke,acute myocardial infarction,and systolic blood pressure significantly associated with the CI-AKI were identified.The cutoff value of CI-AKI risk score was-1.953.The CI-AKI prediction nomogram obtained good discrimination(C-statistic,0.718,95%CI:0.637 to 0.800,p = 7.23 × 10-5)and was well calibrated with Hosmer-Lemeshow ?2 statistic of 5.829(p= 0.120).[Conclusions]The novel nomogram we developed is a simple and accurate tool for preprocedural prediction of CI-AKI in patients undergoing CAG or PCI.This low-cost tool allows assessment of the risk of CI-AKI before contrast exposure,allowing for timely initiation of appropriate preventive measures.