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To the Editor:

I read with interest the article by Rimola et al.1 on the magnetic resonance (MR) findings of intrahepatic cholangiocarcinoma (ICC). The authors stated that the most characteristic MR contrast pattern for ICC in cirrhosis was progressive contrast uptake throughout the different phases, while contrast washout during delayed phases was not observed. As the authors pointed out, a significant number of ICC nodules were reported to display washout on dynamic computed tomography (CT) imaging, and this could be taken as a potential for a false positive diagnosis of hepatocellular carcinoma (HCC) if noninvasive diagnostic criteria of the American Association for the Study of Liver Diseases (AASLD) guidelines are applied.1–3 This article suggests that a false diagnosis of HCC can be minimized based on the MR findings, especially for delayed imaging. I agree with the authors on the main concepts of the study, but I would like to make some comments as follows.

First, the number of ICCs was relatively small, as the authors have pointed out in the text. Moreover, the diagnostic challenge between ICCs and HCCs is usually confined to small tumors less than 3 cm in size.2 The number of small ICCs less than 3 cm in size was only 20 in this series, and was not sufficiently large to allow for a decisive conclusion regarding a diagnosis.

Second, the peripheral region of the medullary subtype of cholangiocarcinoma with abundant tumor cells is known to show prominent early enhancement on MR imaging.4 In fact, a small number of ICC tumors with early enhancement and delayed washout pattern on MR imaging have already been reported, although these are very rare.4, 5 Areas of an ICC with early enhancement and rapid washout pattern seem to indicate active growth.3 Again, I feel that a final conclusion for the specificity of delayed MR imaging requires further large-scale studies in patients with cirrhosis.

In addition, some metastatic lesions from a hypervascular primary neoplasm can also show early enhancement and delayed washout of contrast material.6 However, in these tumors, washout is usually limited to the peripheral portion of the tumors (rim sign), which is a specific finding for the presence of a metastasis.6 Therefore, these observations would not weaken the strength of the present AASLD guidelines.

It seems evident that the use of liver MR imaging, especially with delayed phase images, is very promising for the differential diagnosis of liver tumors. However, I think that the chance of a false diagnosis of an HCC can be minimized only when these potential limitations are considered together. Future large-scale studies will be essential to obtain definite diagnostic conclusions.

References

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  • 1
    Rimola J, Forner A, Reig M, Vilana R, de Lope CR, Ayuso C, et al. Cholangiocarcinoma in cirrhosis: absence of contrast washout in delayed phases by MR avoids misdiagnosis of hepatocellular carcinoma. HEPATOLOGY 2009;doi:10.1002/hep.23071.
  • 2
    Kim SJ, Lee JM, Han JK, Kim KH, Lee JY, Choi BI. Peripheral mass-forming cholangiocarcinoma in cirrhotic liver. AJR Am J Roentgenol 2007; 189: 14281434.
  • 3
    Chung YE, Kim MJ, Park YN, Choi JY, Pyo JY, Kim YC, et al. Varing appearances of cholangiocarcinoma: radiologic-pathologic correlation. Radiographics 2009; 29: 683700.
  • 4
    Murakami T, Nakamura H, Tsuda K, Ishida T, Tomoda K, Hori S, et al. Contrast-enhanced MR imaging of intrahepatic cholangiocarcinoma: pathologic correlation study. J Magn Reson Imaging 1995; 5: 165170.
  • 5
    Zhang Y, Uchida M, Abe T, Nishimura H, Hayabuchi N, Nakashima Y. Intrahepatic peripheral cholangiocarcinoma: comparison of dynamic CT and dynamic MRI. J Comput Assist Tomogr 1999; 23: 670677.
  • 6
    Quillin SP, Atilla S, Brown JJ, Borrello JA, Yu CY, Pilgram TK. Characterization of focal hepatic masses by dynamic contrast-enhanced MR imaging: findings in 311 lesions. Magn Reson Imaging 1997; 15: 275285.

Yun Ku Cho M.D.*, * Department of Radiology, Seoul Veterans Hospital, Seoul, Korea.