title: The target sign in colorectal liver metastases: an atypical Gd-EOB-DTPA "uptake" on the hepatobiliary phase of MR imaging.
abstract: OBJECTIVE
  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.
  
  
  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.
  
  
  RESULTS
  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) mm(2)/s (range 1.10-1.45 × 10(-3) mm(2)/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.
  
  
  CONCLUSIONS
  A number of metastases show an atypical contrast medium uptake during the hepatobiliary phase of gadoxetic acid-enhanced MRI, consisting in a target appearance.
authors.affiliation: First Department of Radiology, Istituto Nazionale Tumori Fondazione G.Pascale, via Mariano Semmola, 80131, Naples, Italy.
authors.forename: Vincenza
authors.initials: V
authors.lastname: Granata
authors.affiliation: First Department of Radiology, Istituto Nazionale Tumori Fondazione G.Pascale, via Mariano Semmola, 80131, Naples, Italy. orlandcat@tin.it.
authors.forename: Orlando
authors.initials: O
authors.lastname: Catalano
authors.affiliation: First Department of Radiology, Istituto Nazionale Tumori Fondazione G.Pascale, via Mariano Semmola, 80131, Naples, Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: Fusco
authors.affiliation: Department of Pathology, Istituto Nazionale Tumori Fondazione G.Pascale, via Mariano Semmola, 80131, Naples, Italy.
authors.forename: Fabiana
authors.initials: F
authors.lastname: Tatangelo
authors.affiliation: Department of Colorectal Surgical Oncology, Istituto Nazionale Tumori Fondazione G.Pascale, via Mariano Semmola, 80131, Naples, Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Rega
authors.affiliation: Department of Colorectal Medical Oncology, Istituto Nazionale Tumori Fondazione G.Pascale, via Mariano Semmola, 80131, Naples, Italy.
authors.forename: Guglielmo
authors.initials: G
authors.lastname: Nasti
authors.affiliation: Department of Abdominal Medical Oncology, Istituto Nazionale Tumori Fondazione G.Pascale, via Mariano Semmola, 80131, Naples, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Avallone
authors.affiliation: Department of Hepatobiliary Surgery, Istituto Nazionale Tumori Fondazione G.Pascale, via Mariano Semmola, 80131, Naples, Italy.
authors.forename: Mauro
authors.initials: M
authors.lastname: Piccirillo
authors.affiliation: Department of Hepatobiliary Surgery, Istituto Nazionale Tumori Fondazione G.Pascale, via Mariano Semmola, 80131, Naples, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Izzo
authors.affiliation: First Department of Radiology, Istituto Nazionale Tumori Fondazione G.Pascale, via Mariano Semmola, 80131, Naples, Italy.
authors.forename: Antonella
authors.initials: A
authors.lastname: Petrillo
mesh_terms: D000328:Adult; D000368:Aged; D001659:Biliary Tract / Q000473:pathology; D015179:Colorectal Neoplasms / Q000473:pathology*; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D007089:Image Enhancement; D008099:Liver / Q000473:pathology; D008113:Liver Neoplasms / Q000556:secondary*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D016609:Neoplasms, Second Primary / Q000473:pathology*; D012189:Retrospective Studies
chemical_list: D003287:Contrast Media; C073590:gadolinium ethoxybenzyl DTPA; D019786:Gadolinium DTPA
keywords: Colorectal cancer; Gadoxetic acid; Liver metastasis; Magnetic resonance imaging