title: Does the measurement of the difference of resistive indexes in spleen and kidney allow a selective assessment of chronic kidney injury?
abstract: OBJECTIVE
  To determine whether the difference of resistive indexes (RIs) in spleen and kidney (DI-RISK) is a more specific ultrasonographic (US) marker of intrarenal parenchymal damage than intrarenal RI alone.
  
  
  METHODS
  The study was approved by the local ethics committee. All study participants provided informed consent. The authors defined standard values for renal RI, splenic RI, and DI-RISK in 152 healthy subjects; carotid intima media thickness (IMT) was assessed as a marker of systemic vascular disease. Next, the authors measured these US parameters and collected echocardiographic data in 290 patients with chronic kidney disease (stage 2-4) recruited between September 2008 and February 2011 to evaluate the DI-RISK across the spectrum of stages of kidney function. Correlation coefficients were calculated with the Spearman test, and multivariate linear regression was used to analyze independent predictors of renal RI, splenic RI, and DI-RISK.
  
  
  RESULTS
  Healthy subjects had a mean age of 34.3 years ± 8.7, and patients with chronic kidney disease had a mean age of 65.0 years ± 12.3 (P < .001). In healthy subjects, both renal and splenic RIs were associated with IMT (renal RI: r = 0.19, P = .022; splenic RI: r = 0.23, P = .005); there was no correlation between DI-RISK and IMT (r = -0.10, P = .215). Similarly, in patients with chronic kidney disease, renal and splenic RIs correlated with IMT (renal RI: r = 0.33, P < .001; splenic RI: r = 0.30, P = .001). DI-RISK was associated with the estimated glomerular filtration rate (eGFR; r = -0.19, P = .001) but not with IMT (r = 0.08, P = .174). At multivariate regression analysis, DI-RISK was independently associated with eGFR but not with extrarenal factors.
  
  
  CONCLUSIONS
  In patients with chronic kidney disease, renal RIs do not selectively indicate organ damage, but also mirror systemic vascular disease. The authors introduced DI-RISK as a potential US marker that may more specifically reflect kidney damage.
authors: Department of Internal Medicine IV-Nephrology and Hypertension, Saarland University Hospital, Kirrberger Strasse, 66421 Homburg/Saar, Germany.
authors: Oliver S
authors: OS
authors: Grün
authors: Esther
authors: E
authors: Herath
authors: Anja
authors: A
authors: Weihrauch
authors: Franziska
authors: F
authors: Flügge
authors: Kyrill S
authors: KS
authors: Rogacev
authors: Danilo
authors: D
authors: Fliser
authors: Gunnar H
authors: GH
authors: Heine
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D004452:Echocardiography; D005260:Female; D006801:Humans; D007668:Kidney / Q000098:blood supply* / Q000000981:diagnostic imaging* / Q000503:physiopathology; D007676:Kidney Failure, Chronic / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D007677:Kidney Function Tests; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D018570:Risk Assessment; D012307:Risk Factors; D013154:Spleen / Q000098:blood supply* / Q000000981:diagnostic imaging* / Q000503:physiopathology; D018709:Statistics, Nonparametric; D011795:Surveys and Questionnaires; D018608:Ultrasonography, Doppler; D014655:Vascular Resistance / Q000502:physiology*