title: Hypovascular hepatic nodules at gadoxetic acid-enhanced MRI: whole-lesion hepatobiliary phase histogram metrics for prediction of progression to arterial-enhancing hepatocellular carcinoma.
abstract: OBJECTIVE
  To explore whole-lesion histogram analysis of the hepatobiliary phase (HBP) defect in indeterminate hypovascular liver lesions for predicting progression to arterial-enhancing hepatocellular carcinoma (HCC).
  
  
  METHODS
  Twenty patients undergoing gadoxetic acid-enhanced MRI for HCC screening with 12° and 25° flip angle (FA) HBP acquisitions demonstrating an indeterminate lesion showing HBP hypointensity but no arterial enhancement were included. Volumes-of-interest were placed on HBP defects, from which histogram metrics were obtained. Associations between these metrics and progression to arterial-enhancing HCC on follow-up imaging were investigated. Lesions were also assessed for the presence of a signal abnormality on conventional sequences.
  
  
  RESULTS
  40% of lesions progressed to arterial-enhancing HCC; 60% were stable at ≥6 months follow-up. Neither T2-hyperintensity increased diffusion signal nor portal/equilibrium phase washout was different between progressing and nonprogressing lesions (p = 1.0). Among direct signal intensity-based measures (overall mean; mean of bottom 10th, 10-25th, and 25-50th percentiles), area-under-the-curve (AUC) for prediction of progression to arterial-enhancing HCC was consistently higher at 25° (range 0.619-0.657) than at 12° (range 0.512-0.548). However, at both FAs, the four measures with highest AUC were measures related to lesion texture and heterogeneity [standard deviation (SD), coefficient of variation (CV), skewness, and entropy], having AUC of 0.655-0.750 at 12° and 0.686-0.800 at 25. The metric with highest AUC at 12° was SD (AUC = 0.750) and at 25° was CV (AUC = 0.800).
  
  
  CONCLUSIONS
  Whole-lesion histogram HBP measures of indeterminate hypovascular liver lesions may help predict progression to arterial-enhancing HCC by reflecting greater lesion heterogeneity, particularly at higher FA. Larger studies are therefore warranted.
authors.affiliation: Department of Radiology, NYU School of Medicine, NYU Langone Medical Center, 550 First Avenue, New York, NY, 10016, USA. andrew.rosenkrantz@nyumc.org.
authors.forename: Andrew B
authors.initials: AB
authors.lastname: Rosenkrantz
authors.affiliation: Department of Radiology, NYU School of Medicine, NYU Langone Medical Center, 550 First Avenue, New York, NY, 10016, USA.
authors.forename: Niveditha
authors.initials: N
authors.lastname: Pinnamaneni
authors.affiliation: Department of Radiology, NYU School of Medicine, NYU Langone Medical Center, 550 First Avenue, New York, NY, 10016, USA.
authors.forename: Andrea S
authors.initials: AS
authors.lastname: Kierans
authors.affiliation: Department of Radiology, NYU School of Medicine, NYU Langone Medical Center, 550 First Avenue, New York, NY, 10016, USA.
authors.forename: Justin M
authors.initials: JM
authors.lastname: Ream
mesh_terms: D006528:Carcinoma, Hepatocellular / Q000473:pathology*; D003287:Contrast Media / Q000008:administration & dosage; D018450:Disease Progression; D005260:Female; D019786:Gadolinium DTPA / Q000008:administration & dosage; D006801:Humans; D008113:Liver Neoplasms / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009389:Neovascularization, Pathologic / Q000473:pathology*; D010865:Pilot Projects; D011230:Precancerous Conditions / Q000098:blood supply* / Q000473:pathology*; D015203:Reproducibility of Results; D012189:Retrospective Studies
chemical_list: D003287:Contrast Media; C073590:gadolinium ethoxybenzyl DTPA; D019786:Gadolinium DTPA
keywords: Gadoxetic acid; Hepatobiliary; Hepatocellular carcinoma; Liver; MRI