title: Incremental value of liver MR imaging in patients with potentially curable colorectal hepatic metastasis detected at CT: a prospective comparison of diffusion-weighted imaging, gadoxetic acid-enhanced MR imaging, and a combination of both MR techniques.
abstract: OBJECTIVE
  To prospectively compare diagnostic performance of diffusion-weighted (DW) imaging, gadoxetic acid-enhanced magnetic resonance (MR) imaging, both techniques combined (combined MR imaging), and computed tomography (CT) for detecting colorectal hepatic metastases and evaluate incremental value of MR for patients with potentially curable colorectal hepatic metastases detected with CT.
  
  
  METHODS
  In this institutional review board-approved prospective study, with informed consent, 51 patients (39 men, 12 women; mean age, 62 years) with potentially resectable hepatic metastases detected with CT underwent liver MR, including DW imaging and gadoxetic acid-enhanced MR. Two independent readers reviewed DW, gadoxetic acid-enhanced, combined MR, and CT image sets to detect hepatic metastases. The figure-of-merit (FOM) value representing overall diagnostic performance, sensitivity, and positive predictive value (PPV) for each image set were analyzed by using free-response receiver operating characteristic analysis and generalized estimating equations.
  
  
  RESULTS
  There were 104 hepatic metastases in 47 patients. The pooled FOM values, sensitivities, and PPVs of combined MR (FOM value, 0.93; sensitivity, 98%; and PPV, 88%) and gadoxetic acid-enhanced MR (FOM value, 0.92; sensitivity, 95%; and PPV, 90%) were significantly higher than those of CT (FOM value, 0.82; sensitivity, 85%; and PPV, 73%) (P < .006). The pooled FOM value and sensitivity of combined MR (FOM value, 0.92; sensitivity, 95%) was also significantly higher than that of DW imaging (FOM value, 0.82; sensitivity, 79%) for metastases (≤1-cm diameter) (P ≤ .003). DW imaging showed significantly higher pooled sensitivity (79%) and PPV (60%) than CT (sensitivity, 50%; PPV, 33%) for the metastases (≤1-cm diameter) (P ≤ .004). In 47 patients with hepatic metastases, combined MR depicted more metastases than CT in 10 and 14 patients, respectively, according to both readers.
  
  
  CONCLUSIONS
  Gadoxetic acid-enhanced MR and combined MR are more accurate than CT in detecting colorectal hepatic metastases, have an incremental value when added to CT alone for detecting additional metastases, and can be routinely performed in patients with potentially curable hepatic metastases detected with CT.
authors.affiliation: From the Department of Radiology and Research Institute of Radiology (H.J.K., S.S.L., J.H.B., S.H.P., A.Y.K., H.K.H.) and Department of Surgery (J.C.K., C.S.Y.), University of Ulsan College of Medicine, Asan Medical Center, 86 Asanbyeongwon-Gil, Songa-Gu, Seoul 138-736, Korea.
authors.forename: Hye Jin
authors.initials: HJ
authors.lastname: Kim
authors.forename: Seung Soo
authors.initials: SS
authors.lastname: Lee
authors.forename: Jae Ho
authors.initials: JH
authors.lastname: Byun
authors.forename: Jin Cheon
authors.initials: JC
authors.lastname: Kim
authors.forename: Chang Sik
authors.initials: CS
authors.lastname: Yu
authors.forename: Seong Ho
authors.initials: SH
authors.lastname: Park
authors.forename: Ah Young
authors.initials: AY
authors.lastname: Kim
authors.forename: Hyun Kwon
authors.initials: HK
authors.lastname: Ha
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015179:Colorectal Neoplasms / Q000473:pathology*; D003287:Contrast Media; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D008113:Liver Neoplasms / Q000175:diagnosis* / Q000556:secondary*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods
chemical_list: D003287:Contrast Media; C073590:gadolinium ethoxybenzyl DTPA; D019786:Gadolinium DTPA