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J. W. Goethe University Hospital Frankfurt, Germany
Saarland University Homburg/Saar, Germany
J. W. Goethe University Hospital Frankfurt, Germany
WEB—This is a Web exclusive article.
F2, 0.88 for F
F3, and 0.88 for F = F4—were similar to those revealed in the APRI
evaluation study by Wai et al.
[4] and higher than in previous
studies comparing the APRI with the biochemical test, FibroTest
(BioPredictive), and transient elastography (FibroScan, Echosens).
The results of the APRI in our study
[2] were superior to the
real-time elastography findings. However, a significantly higher diagnostic
accuracy than for the APRI was obtained by a mathematic combination of the
elasticity score and two routine laboratory parameters (platelet count and
-glutamyl transpeptidase [GGT]) with AUC of 0.93 for the diagnosis of
significant fibrosis (F F2), 0.95 for the diagnosis of severe fibrosis (F
F3), and 0.91 for the diagnosis of cirrhosis (F = F4). Especially for the
differentiation between F0 or F1 versus F2, F3, or F4 and F0, F1, or F2 versus
F3 or F4, the combination score was clearly superior to the APRI. Therefore,
we suggest a combination of real-time elastography with routine laboratory
values rather than using the APRI alone.
Concerning cost-effectiveness, the real-time elastography is integrated in a routine sonography scanner. Thus, after a single activation of the elastography module, which is relatively economic in relation to the overall cost of the sonography scanner, real-time elastography can be performed during routine sonography in a timely manner. However, we reemphasize that our study [2] is a "proof-of-principle" study, and further studies are needed before implementation into clinical practice can be recommended.
Of course besides GGT and platelet count, the variables of age and cholesterol, also analyzed in the Forns index, were considered in the multivariate regression analysis. However, GGT and platelet count were the only independent predictors. Real-time elastography was evaluated twice in 16 patients to assess the reproducibility of different variables characterizing elasticity. Ten variables with high reproducibility were then selected for the final analysis. Reproducibility was not evaluated in an independent patient group in this study [2]. Therefore, reproducibility of results may be misleading because it would certainly be overestimated.
The same applies for the intra- and interobserver variability. Because our study [2] was a proof-of-principle study, our goal was to optimize a formula for the calculation of elasticity by choosing variables with high intra- and interobserver reproducibility and not to evaluate the intra- and interobserver variability. Ongoing studies will evaluate the reproducibility as well as the intra- and interobserver variability (within- and between-session) of this formula in an independent patient group. In our study, all examinations were performed by the same operator, except for the analysis of reproducibility in the mentioned 16 patients for whom a second operator performed an additional examination. Both operators were experienced in sonography. Future studies are needed to evaluate whether different levels of training and experience affect the results.
The group of patients categorized as F4 consisted of four patients with histologically proven liver cirrhosis and 20 patients with clinically and sonographically overt signs of liver cirrhosis without histology. This, of course, is a heterogenic patient population. However, no significant difference was found between the histologically proven and the clinically proven patient groups for the APRI score (p = 0.44) and for the elasticity–laboratory combination score (p = 0.35) for the diagnosis of liver cirrhosis. A difference was only found for real-time elastography alone for the diagnosis of liver cirrhosis, with significantly higher real-time elastography values in the group of patients with clinically proven liver cirrhosis (p = 0.02). However, because of the small number of cases of histologically proven liver cirrhosis, we did not further differentiate between both cirrhosis groups.
High interobserver variability concerning the staging of liver fibrosis has
been shown in histology studies
[5]. The differentiation of
fibrosis stages (particularly F0 or F1 from F2, F3, or F4) is of special
clinical value rather than the exact prediction of a liver fibrosis stage to
identify patients who need treatment. Therefore, according to clinical
practice, diagnostic accuracies for patients with chronic viral hepatitis and
significant fibrosis ( F2), severe fibrosis ( F3), and cirrhosis (F4)
were chosen with the aim of aiding the treatment decision.
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  A. Saftoiu, D. I. Gheonea, and T. Ciurea Reply Am. J. Roentgenol., June 1, 2008; 190(6): W372 - W373. [Full Text] [PDF]
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