Viscoelastic parameters for quantifying liver fibrosis: three-dimensional multifrequency MR elastography study on thin liver rat slices.
OBJECTIVE
To assess in a high-resolution model of thin liver rat slices which viscoelastic parameter at three-dimensional multifrequency MR elastography has the best diagnostic performance for quantifying liver fibrosis.


METHODS
The study was approved by the ethics committee for animal care of our institution. Eight normal rats and 42 rats with carbon tetrachloride induced liver fibrosis were used in the study. The rats were sacrificed, their livers were resected and three-dimensional MR elastography of 5 ± 2 mm liver slices was performed at 7T with mechanical frequencies of 500, 600 and 700 Hz. The complex shear, storage and loss moduli, and the coefficient of the frequency power law were calculated. At histopathology, fibrosis and inflammation were assessed with METAVIR score, fibrosis was further quantified with morphometry. The diagnostic value of the viscoelastic parameters for assessing fibrosis severity was evaluated with simple and multiple linear regressions, receiver operating characteristic analysis and Obuchowski measures.


RESULTS
At simple regression, the shear, storage and loss moduli were associated with the severity of fibrosis. At multiple regression, the storage modulus at 600 Hz was the only parameter associated with fibrosis severity (r = 0.86, p<0.0001). This parameter had an Obuchowski measure of 0.89+/-0.03. This measure was significantly larger than that of the loss modulus (0.78+/-0.04, p = 0.028), but not than that of the complex shear modulus (0.88+/-0.03, p = 0.84).


CONCLUSIONS
Our high resolution, three-dimensional multifrequency MR elastography study of thin liver slices shows that the storage modulus is the viscoelastic parameter that has the best association with the severity of liver fibrosis. However, its diagnostic performance does not differ significantly from that of the complex shear modulus.
Department of Radiology, Beaujon University Hospitals Paris Nord Val de Seine, Clichy, France; University Paris Diderot, Sorbonne Paris Cité, France; IPMA, INSERM U773, Centre de Recherche Biomédicale Bichat-Beaujon, Paris, France.
Maxime
M
Ronot
University Paris Diderot, Sorbonne Paris Cité, France; IPMA, INSERM U773, Centre de Recherche Biomédicale Bichat-Beaujon, Paris, France.
Simon A
SA
Lambert
Department of Radiology, Beaujon University Hospitals Paris Nord Val de Seine, Clichy, France; University Paris Diderot, Sorbonne Paris Cité, France; IPMA, INSERM U773, Centre de Recherche Biomédicale Bichat-Beaujon, Paris, France.
Mathilde
M
Wagner
University Paris Diderot, Sorbonne Paris Cité, France; IPMA, INSERM U773, Centre de Recherche Biomédicale Bichat-Beaujon, Paris, France.
Philippe
P
Garteiser
University Paris Diderot, Sorbonne Paris Cité, France; IPMA, INSERM U773, Centre de Recherche Biomédicale Bichat-Beaujon, Paris, France.
Sabrina
S
Doblas
IPMA, INSERM U773, Centre de Recherche Biomédicale Bichat-Beaujon, Paris, France; Department of Pathology, Beaujon University Hospitals Paris Nord Val de Seine, Clichy, France.
Miguel
M
Albuquerque
University Paris Diderot, Sorbonne Paris Cité, France; IPMA, INSERM U773, Centre de Recherche Biomédicale Bichat-Beaujon, Paris, France; Department of Pathology, Beaujon University Hospitals Paris Nord Val de Seine, Clichy, France.
Valérie
V
Paradis
Department of Radiology, Beaujon University Hospitals Paris Nord Val de Seine, Clichy, France; University Paris Diderot, Sorbonne Paris Cité, France; IPMA, INSERM U773, Centre de Recherche Biomédicale Bichat-Beaujon, Paris, France.
Valérie
V
Vilgrain
University Paris Diderot, Sorbonne Paris Cité, France; IPMA, INSERM U773, Centre de Recherche Biomédicale Bichat-Beaujon, Paris, France.
Ralph
R
Sinkus
Department of Radiology, Beaujon University Hospitals Paris Nord Val de Seine, Clichy, France; University Paris Diderot, Sorbonne Paris Cité, France; IPMA, INSERM U773, Centre de Recherche Biomédicale Bichat-Beaujon, Paris, France.
Bernard E
BE
Van Beers
D000818:Animals; D002251:Carbon Tetrachloride; D004548:Elasticity; D054459:Elasticity Imaging Techniques; D008099:Liver / Q000473:pathology*; D008103:Liver Cirrhosis / Q000139:chemically induced / Q000473:pathology*; D008297:Male; D051381:Rats; D017208:Rats, Wistar
D002251:Carbon Tetrachloride