title: Acoustic radiation force impulse imaging for noninvasive evaluation of renal parenchyma elasticity: preliminary findings.
abstract: OBJECTIVE
  To evaluate the diagnostic value of acoustic radiation force impulse (ARFI) to test the elasticity of renal parenchyma by measuring the shear wave velocity (SWV) which might be used to detect chronic kidney disease (CKD).
  
  
  METHODS
  327 healthy volunteers and 64 CKD patients were enrolled in the study. The potential influencing factors and measurement reproducibility were evaluated in the healthy volunteers. Correlations between SWV and laboratory tests were analyzed in CKD patients.?Receiver-operating characteristic curve (ROC) analyses were performed to assess the diagnostic performance of ARFI.
  
  
  RESULTS
  The SWV of healthy volunteers correlated significantly to age (r = -0.22, P<0.001, n = 327) and differed significantly between men and women (2.06±0.48 m/s vs. 2.2±0.52 m/s, P = 0.018, n = 327). However, it did not correlate significantly to height, weight, body mass index, waistline, kidney dimension and the depth for SWV measurement (n = 30). Inter- and intraobserver agreement expressed as intraclass coefficient correlation were 0.64 (95% CI: 0.13 to 0.82, P = 0.011) and 0.6 (95% CI: 0.31 to 0.81, P = 0.001) (n = 40). The mean SWV in healthy volunteers was 2.15±0.51 m/s, while was 1.81±0.43 m/s, 1.79±0.29 m/s, 1.81±0.44 m/s, 1.64±0.55 m/s, and 1.36±0.17 m/s for stage 1, 2, 3, 4 and 5 in CKD patients respectively. The SWV was significantly higher for healthy volunteers compared with each stage in CKD patients. ARFI could not predict the different stages of CKD except stage 5. In CKD patients, SWV correlated to e-GFR (r = 0.3, P = 0.018), to urea nitrogen (r =  -0.3, P = 0.016), and to creatinine (r =  -0.41, P = 0.001). ROC analyses indicated that the area under the ROC curve was 0.752 (95% CI: 0.704 to 0.797) (P<0.001). The cut-off value for predicting CKD was 1.88 m/s (sensitivity 71.87% and specificity 69.69%).
  
  
  CONCLUSIONS
  ARFI may be a potentially useful tool in detecting CKD.
authors.affiliation: Department of Medical Ultrasound, Shanghai Tenth People's Hospital, Tenth People's Hospital of Tongji University, Shanghai, China.
authors.forename: Le-Hang
authors.initials: LH
authors.lastname: Guo
authors.forename: Hui-Xiong
authors.initials: HX
authors.lastname: Xu
authors.forename: Hui-Jun
authors.initials: HJ
authors.lastname: Fu
authors.forename: Ai
authors.initials: A
authors.lastname: Peng
authors.forename: Yi-Feng
authors.initials: YF
authors.lastname: Zhang
authors.forename: Lin-Na
authors.initials: LN
authors.lastname: Liu
mesh_terms: D000162:Acoustics; D000368:Aged; D003952:Diagnostic Imaging / Q000379:methods*; D004548:Elasticity; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007668:Kidney / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D051436:Renal Insufficiency, Chronic / Q000175:diagnosis* / Q000000981:diagnostic imaging*; D015203:Reproducibility of Results