title: Acoustic radiation force impulse quantification of spleen elasticity for assessing liver fibrosis.
abstract: OBJECTIVE
  The purpose of this study is to assess the correlation between liver fibrosis and spleen stiffness measured by ARFI in patients with chronic viral hepatitis (B or C) and to explore the possible complementary role of spleen and liver ARFI in grading liver fibrosis.
  
  
  METHODS
  84 subjects (51 patients, 33 healthy volunteers) were enrolled. ARFI of the spleen and the liver was performed. Patients subsequently underwent liver biopsy for grading liver fibrosis according to Knodell scoring system. Multivariate logistic regression and decision tree analysis were adopted to test the relationship between spleen and liver stiffness (independent variables) and liver fibrosis (F1< vs. ≥F3). Leave-One-Out Cross-Validation was used for validating the predictive classification models. Area under the ROC curve (AUROCC) was used as accuracy metric.
  
  
  RESULTS
  Spleen ARFI was able to discriminate early (F1) from severe (≥F3) liver fibrosis with an optimal cut-off of 3.05 m/s: AUROCC 0.807, cross-validated AUROCC 0.614. Liver ARFI was superior to spleen ARFI, using a cut-off of 2.11 m/s: AUROCC 0.879, cross-validated AUROCC 0.672. Neither spleen nor liver ARFI was able to differentiate healthy volunteers from F1 patients. Odds ratios derived from logistic regression were 23.1 and 9.9 for liver and spleen ARFI, respectively; resulting AUROCC was 0.905 (cross-validated 0.848). A decision tree considering the sequential use of liver and spleen ARFI with cut-off of 2.14 and 3.39 m/s, respectively, resulted in AUROCC of 0.903 (cross-validated 0.7).
  
  
  CONCLUSIONS
  Spleen ARFI has the potential to discriminate early from severe liver fibrosis. Spleen and liver ARFI, when combined, show a better discriminative power than liver ARFI alone.
authors.affiliation: Department of Radiology, University of Brescia, Piazzale Spedali Civili 1, 25123, Brescia, Italy, paolocab@libero.it.
authors.forename: Paolo
authors.initials: P
authors.lastname: Cabassa
authors.forename: Marco
authors.initials: M
authors.lastname: Ravanelli
authors.forename: Angelo
authors.initials: A
authors.lastname: Rossini
authors.forename: Gianbattista
authors.initials: G
authors.lastname: Contessi
authors.forename: Raed
authors.initials: R
authors.lastname: Almajdalawi
authors.forename: Roberto
authors.initials: R
authors.lastname: Maroldi
mesh_terms: D000328:Adult; D019540:Area Under Curve; D004311:Double-Blind Method; D004548:Elasticity; D054459:Elasticity Imaging Techniques; D005260:Female; D019698:Hepatitis C, Chronic / Q000000981:diagnostic imaging*; D006801:Humans; D008099:Liver / Q000000981:diagnostic imaging; D008103:Liver Cirrhosis / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012372:ROC Curve; D015203:Reproducibility of Results; D013154:Spleen / Q000000981:diagnostic imaging*