title: Hepatic fat quantification using the proton density fat fraction (PDFF): utility of free-drawn-PDFF with a large coverage area.
abstract: OBJECTIVE
  To evaluate the diagnostic performance of magnetic resonance imaging-estimated proton density fat fraction (MRI-PDFF) using a free-drawn region-of-interest (ROI) measurement of hepatic fat deposition compared to MR spectroscopy (MRS) as the reference standard.
  
  
  METHODS
  A total of 156 patients underwent 3T MR imaging with a multi-step adaptive fitting approach, multi-echo volume interpolated breath-hold examination (VIBE) acquisition and single-voxel high-speed T2-corrected multiple-echo (1)H-MR spectroscopy (SVS). Seven ROI measurements were performed in each segment of the fat percentage maps ("segmental-PDFF"). Three ROIs were placed at the same level as the SVS ("VOI-PDFF"). Free-hand-drawn ROIs were placed at three different levels along the entire liver ("free-drawn-PDFF") and separately along the right and left lobes ("free-drawn-PDFF-2").
  
  
  RESULTS
  A strong correlation was found between VOI-PDFF and SVS (r = 0.977). The right lobe had greater fat content than the left lobe (p < 0.001). After image analysis, 54 and 46 patients were classified as having steatosis using SVS and free-drawn-PDFF as a reference standard, respectively. The diagnostic performance of free-drawn-PDFF was significantly different from SVS (p < 0.05).
  
  
  CONCLUSIONS
  Free-drawn-PDFF provides accurate and generalized information regarding hepatic fat deposition. It is a useful method, particularly if fat deposition is heterogeneous, and should be considered as a new reference standard.
authors.affiliation: Department of Radiology, Chonbuk National University Medical School and Hospital, Research Institute of Clinical Medicine of Chonbuk National University-Biomedical Research Institute of Chonbuk National University Hospital, 20 Geonji-ro, Deokjin-gu, Jeonju-Si, Chonbuk, 561-712, Korea.
authors.forename: Kun Young
authors.initials: KY
authors.lastname: Kim
authors.affiliation: Department of Radiology, Chonbuk National University Medical School and Hospital, Research Institute of Clinical Medicine of Chonbuk National University-Biomedical Research Institute of Chonbuk National University Hospital, 20 Geonji-ro, Deokjin-gu, Jeonju-Si, Chonbuk, 561-712, Korea. pichgo@gmail.com.
authors.forename: Ji Soo
authors.initials: JS
authors.lastname: Song
authors.affiliation: MR Applications Development, Siemens Healthcare, Erlangen, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Kannengiesser
authors.affiliation: Department of Radiology, Chonbuk National University Medical School and Hospital, Research Institute of Clinical Medicine of Chonbuk National University-Biomedical Research Institute of Chonbuk National University Hospital, 20 Geonji-ro, Deokjin-gu, Jeonju-Si, Chonbuk, 561-712, Korea.
authors.forename: Young Min
authors.initials: YM
authors.lastname: Han
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D005223:Fats / Q000032:analysis*; D005234:Fatty Liver / Q000175:diagnosis; D005260:Female; D006801:Humans; D008099:Liver / Q000737:chemistry*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D012015:Reference Standards
chemical_list: D005223:Fats
keywords: Fat quantification; Hepatic steatosis; MR spectroscopy; Proton density fat fraction