Role of MRI with hepatospecific contrast agent in the identification and characterization of focal liver lesions: pathological correlation in explanted livers.
OBJECTIVE
To assess the diagnostic performance of magnetic resonance imaging (MRI) with gadoxetic acid in the identification of hepatocellular carcinoma (HCC) nodules by comparison with histological findings.


METHODS
In a cohort of patients suffering from cirrhosis of various etiologies (chronic hepatitis C virus (HCV) or hepatitis B virus (HBV), alcohol abuse, cryptogenic forms), we selected 17 patients affected by HCC who were eligible for liver transplantation on the basis of a computed-tomography (CT) total-body examination. Such patients also underwent an MRI examination under basal conditions, and with four dynamic phases, as well as a hepatobiliary phase acquired after at least 20 min and recognized by the excretion of contrast agent into the bile duct, following intravenous administration of 0.05 mol/kg of gadoxetic acid (gadoxetate disodium, Primovist(®); Bayer, Osaka, Japan). The MRI images were then evaluated in a double-blinded experimental setup by two radiologists experienced in imaging of the liver. The diagnosis of HCC was made in the presence of nodular lesions that showed typical or atypical enhancement patterns. The liver was subsequently explanted (on average 47.4 days after MRI evaluation), dissected into 1-cm samples, and histologically evaluated according to the classification of Edmondson-Steiner.


RESULTS
At the histopathological examination, 46 nodules were identified, on average 2.7 nodules for each patient. Of these, 37 were hepatocellular carcinomas, 3 were characterized by histologically unrecognizable complete necrosis, and 6 showed high-grade dysplasia. MRI with hepatospecific contrast medium showed inter-observer average values of sensitivity, specificity, and diagnostic accuracy of 94.6, 90, and 93.6 %, respectively. In one case, a nodule was not identified by MRI with gadoxetic acid, even in the hepatospecific phase (false negative (FN)). This result could be implicated to the long time interval between the analysis and the explant (88 days). In another case, there was an overdiagnosis of a HCC with a typical nodular pattern (false positive (FP)), but which most likely should have been attributed to a previous echinococcus cyst. MRI analysis, in combination with the study of the hepatobiliary phase, also showed a greater sensitivity, the same specificity, and a greater diagnostic accuracy compared to MRI evaluated only in the dynamic phases (with an average percentage between the two operators, respectively, of 75.7, 90, and 78 %).


CONCLUSIONS
MRI with gadoxetic acid shows a diagnostic accuracy superior to contrast-enhanced MRI, allowing for the diagnosis of additional lesions, and it could be considered as an imaging method to carry out a more appropriate management of waiting lists for liver transplants.
Department of Diagnostic and Molecular Imaging, Radiation Therapy and Interventional Radiology, Viale Oxford, 81, 00133, Rome, Italy. aorlacchio@sirm.org.
Antonio
A
Orlacchio
Department of Diagnostic and Molecular Imaging, Radiation Therapy and Interventional Radiology, Viale Oxford, 81, 00133, Rome, Italy.
Fabrizio
F
Chegai
Department of Diagnostic and Molecular Imaging, Radiation Therapy and Interventional Radiology, Viale Oxford, 81, 00133, Rome, Italy.
Sebastiano
S
Fabiano
Department of Diagnostic and Molecular Imaging, Radiation Therapy and Interventional Radiology, Viale Oxford, 81, 00133, Rome, Italy.
Stefano
S
Merolla
Department of Diagnostic and Molecular Imaging, Radiation Therapy and Interventional Radiology, Viale Oxford, 81, 00133, Rome, Italy.
Valentina
V
Funel
Department of Diagnostic and Molecular Imaging, Radiation Therapy and Interventional Radiology, Viale Oxford, 81, 00133, Rome, Italy.
Francesca
F
Di Giuliano
Organ Transplantation Unit, University Hospital Tor Vergata, Rome, Italy.
Matteo
M
Manuelli
Organ Transplantation Unit, University Hospital Tor Vergata, Rome, Italy.
Giuseppe
G
Tisone
Liver Unit, University Hospital Tor Vergata, Rome, Italy.
Simona
S
Francioso
Liver Unit, University Hospital Tor Vergata, Rome, Italy.
Mario
M
Angelico
Pathological Anatomy Unit, University Hospital Tor Vergata, Rome, Italy.
Giampiero
G
Palmieri
Department of Diagnostic and Molecular Imaging, Radiation Therapy and Interventional Radiology, Viale Oxford, 81, 00133, Rome, Italy.
Giovanni
G
Simonetti
D006528:Carcinoma, Hepatocellular / Q000000981:diagnostic imaging* / Q000473:pathology; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D008113:Liver Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D016031:Liver Transplantation; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D011300:Preoperative Care; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed; D014850:Waiting Lists
D003287:Contrast Media; C073590:gadolinium ethoxybenzyl DTPA; D019786:Gadolinium DTPA
HCC diagnosis; HCC therapy; Histopathological correlation; Liver transplant; MRI contrast agent