The target sign in colorectal liver metastases: an atypical Gd-EOB-DTPA “uptake” on the hepatobiliary phase of MR imaging
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To describe the MRI findings in colorectal cancer liver metastases using gadoxetic acid (Gd-EOB-DTPA), with special emphasis on the target feature seen on the hepatobiliary phase.
Material and methods
The medical records of 45 colorectal cancer patients with an overall number of 150 liver metastases were reviewed. All patients underwent Gd-EOB-DTPA-enhanced MRI before any kind of treatment. We retrospectively evaluated, for each lesion, the signal intensity on the T1-weighted, T2-weighted, and diffusion-weighted images. Additionally, the enhancement pattern during the arterial-, portal-, equilibrium-, and hepatobiliary-phase was assessed. Fourteen lesions had a pathological correlation.
Lesions size was 5–40 mm (mean 15 mm). All metastases were hypointense on T1-w imaging. Ninety-nine lesions (66%) had a central area of very high signal intensity on T2-w imaging. Fifty-one metastases (34%) were hyperintense on the T2-w images. In DWI, all lesions had a restricted diffusion. The mean ADC value was 1.31 × 10−3 mm2/s (range 1.10–1.45 × 10−3 mm2/s). During the arterial-phase imaging, 61 lesions (41%) showed a rim enhancement, while 89 lesions (59%) appeared as hypointense. All lesions had low signal intensity in the portal and equilibrium phase. Thirty-nine percent of the lesions also showed an enhancing rim on the portal-phase images. During the hepatobiliary phase, 80 lesions (53.3%) were hypointense, while 70 lesions (46.7%) had a target appearance.
A number of metastases show an atypical contrast medium uptake during the hepatobiliary phase of gadoxetic acid-enhanced MRI, consisting in a target appearance.
KeywordsColorectal cancer Liver metastasis Magnetic resonance imaging Gadoxetic acid
The authors are grateful to Alessandra Trocino, librarian at the National Cancer Institute of Naples, Italy.
Compliance with Ethical Standards
Conflict of interest
The authors have no conflict of interest to be disclosed.
Human and animal rights and informed consent
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Informed consent was obtained from all individual participants included in the study.
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