title: Reduced Field-of-View Diffusion-Weighted Magnetic Resonance Imaging of the Pancreas: Comparison with Conventional Single-Shot Echo-Planar Imaging.
abstract: OBJECTIVE
  To investigate the image quality (IQ) and apparent diffusion coefficient (ADC) of reduced field-of-view (FOV) di-ffusion-weighted imaging (DWI) of pancreas in comparison with full FOV DWI.
  
  
  METHODS
  In this retrospective study, 2 readers independently performed qualitative analysis of full FOV DWI (FOV, 38 × 38 cm; b-value, 0 and 500 s/mm(2)) and reduced FOV DWI (FOV, 28 × 8.5 cm; b-value, 0 and 400 s/mm(2)). Both procedures were conducted with a two-dimensional spatially selective radiofrequency excitation pulse, in 102 patients with benign or malignant pancreatic diseases (mean size, 27.5 ± 14.4 mm). The study parameters included 1) anatomic structure visualization, 2) lesion conspicuity, 3) artifacts, 4) IQ score, and 5) subjective clinical utility for confirming or excluding initially considered differential diagnosis on conventional imaging. Another reader performed quantitative ADC measurements of focal pancreatic lesions and parenchyma. Wilcoxon signed-rank test was used to compare qualitative scores and ADCs between DWI sequences. Mann Whitney U-test was used to compare ADCs between the lesions and parenchyma.
  
  
  RESULTS
  On qualitative analysis, reduced FOV DWI showed better anatomic structure visualization (2.76 ± 0.79 at b = 0 s/mm(2) and 2.81 ± 0.64 at b = 400 s/mm(2)), lesion conspicuity (3.11 ± 0.99 at b = 0 s/mm(2) and 3.15 ± 0.79 at b = 400 s/mm(2)), IQ score (8.51 ± 2.05 at b = 0 s/mm(2) and 8.79 ± 1.60 at b = 400 s/mm(2)), and higher clinical utility (3.41 ± 0.64), as compared to full FOV DWI (anatomic structure, 2.18 ± 0.59 at b = 0 s/mm(2) and 2.56 ± 0.47 at b = 500 s/mm(2); lesion conspicuity, 2.55 ± 1.07 at b = 0 s/mm(2) and 2.89 ± 0.86 at b = 500 s/mm(2); IQ score, 7.13 ± 1.83 at b = 0 s/mm(2) and 8.17 ± 1.31 at b = 500 s/mm(2); clinical utility, 3.14 ± 0.70) (p < 0.05). Artifacts were significantly improved on reduced FOV DWI (2.65 ± 0.68) at b = 0 s/mm(2) (full FOV DWI, 2.41 ± 0.63) (p < 0.001). On quantitative analysis, there were no significant differences between the 2 DWI sequences in ADCs of various pancreatic lesions and parenchyma (p > 0.05). ADCs of adenocarcinomas (1.061 × 10(-3) mm(2)/s ± 0.133 at reduced FOV and 1.079 × 10(-3) mm(2)/s ± 0.135 at full FOV) and neuroendocrine tumors (0.983 × 10(-3) mm(2)/s ± 0.152 at reduced FOV and 1.004 × 10(-3) mm(2)/s ± 0.153 at full FOV) were significantly lower than those of parenchyma (1.191 × 10(-3) mm(2)/s ± 0.125 at reduced FOV and 1.218 × 10(-3) mm(2)/s ± 0.103 at full FOV) (p < 0.05).
  
  
  CONCLUSIONS
  Reduced FOV DWI of the pancreas provides better overall IQ including better anatomic detail, lesion conspicuity and subjective clinical utility.
authors.affiliation: Department of Radiology, Seoul National University Hospital, Seoul 03080, Korea. ; Aerospace Medical Group, Air Force Education and Training Command, Jinju 52634, Korea.
authors.forename: Hyungjin
authors.initials: H
authors.lastname: Kim
authors.affiliation: Department of Radiology, Seoul National University Hospital, Seoul 03080, Korea. ; Institute of Radiation Medicine, Seoul National University College of Medicine, Seoul 03080, Korea.
authors.forename: Jeong Min
authors.initials: JM
authors.lastname: Lee
authors.affiliation: Department of Radiology, Seoul National University Hospital, Seoul 03080, Korea.
authors.forename: Jeong Hee
authors.initials: JH
authors.lastname: Yoon
authors.affiliation: Department of Surgery, Seoul National University Hospital, Seoul 03080, Korea.
authors.forename: Jin-Young
authors.initials: JY
authors.lastname: Jang
authors.affiliation: Department of Surgery, Seoul National University Hospital, Seoul 03080, Korea.
authors.forename: Sun-Whe
authors.initials: SW
authors.lastname: Kim
authors.affiliation: Division of Gastroenterology, Department of Internal Medicine, Seoul National University College of Medicine, Seoul 03080, Korea.
authors.forename: Ji Kon
authors.initials: JK
authors.lastname: Ryu
authors.affiliation: Siemens Healthcare, Erlangen, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Kannengiesser
authors.affiliation: Department of Radiology, Seoul National University Hospital, Seoul 03080, Korea. ; Institute of Radiation Medicine, Seoul National University College of Medicine, Seoul 03080, Korea.
authors.forename: Joon Koo
authors.initials: JK
authors.lastname: Han
authors.affiliation: Department of Radiology, Seoul National University Hospital, Seoul 03080, Korea. ; Institute of Radiation Medicine, Seoul National University College of Medicine, Seoul 03080, Korea.
authors.forename: Byung Ihn
authors.initials: BI
authors.lastname: Choi
mesh_terms: D000328:Adult; D000368:Aged; D016477:Artifacts; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging; D017352:Echo-Planar Imaging; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010179:Pancreas / Q000000981:diagnostic imaging*; D010182:Pancreatic Diseases / Q000000981:diagnostic imaging* / Q000473:pathology; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology; D011859:Radiography; D012189:Retrospective Studies
keywords: Apparent diffusion coefficient; Diffusion-weighted imaging; Image quality; Magnetic resonance imaging; Pancreas; Reduced field-of-view