title: Diffusion-weighted imaging in the characterization of focal liver lesions: efficacy of visual assessment.
abstract: OBJECTIVE
  The objective of the study was to assess the value of visual assessment of signal intensities on b800 diffusion-weighted images and apparent diffusion coefficient (ADC) maps in differentiation of benign and malignant focal liver lesions (FLLs).
  
  
  METHODS
  Approval for this retrospective study was obtained from the institutional review board. One hundred forty-three FLLs in 65 patients (38 women, 27 men; mean age, 50.8 years) underwent magnetic resonance (MR) imaging and diffusion-weighted imaging (DWI) with a respiratory-triggered single-shot echo-planar imaging sequence. Focal liver lesions were evaluated visually according to the signal intensities on b800 and ADC map images, and ADC values were also calculated. The conventional MR imaging, follow-up imaging findings, and histopathologic data were regarded as gold standard. Normal distribution was assessed with Kolmogorov-Smirnov test. The accuracies of visual assessment and ADC values in differentiating benign and malignant FLLs were assessed with the Student t test, and threshold values were determined with receiver operating characteristic curve analysis.
  
  
  RESULTS
  By using a cutoff value of 1.21 × 10⁻³ mm²/s, ADC had a sensitivity of 100%, a specificity of 89.3%, and an accuracy of 92.3% in the discrimination of malignant FLLs. With the visual assessment of the DWIs and ADC maps, malignant lesions were differentiated from benign ones, with 100% sensitivity, 92.2% specificity, and 94.4% accuracy. Although some benign lesions were interpreted as malignant, no malignant lesion was determined as benign in visual assessment.
  
  
  CONCLUSIONS
  Most FLLs are benign ones such as hemangiomas and cysts, which can be readily and practically characterized only by using visual assessment of DWIs without requiring time-consuming conventional and dynamic contrast-enhanced imaging sequences. Some benign lesions that are falsely interpreted as malignant can be further characterized by using conventional and contrast-enhanced MR studies.
authors.affiliation: Department of Radiology, Gulhane Military Medical School, Ankara, Turkey. bilbat_23@yahoo.com
authors.forename: Bilal
authors.initials: B
authors.lastname: Battal
authors.forename: Murat
authors.initials: M
authors.lastname: Kocaoglu
authors.forename: Veysel
authors.initials: V
authors.lastname: Akgun
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Karademir
authors.forename: Salih
authors.initials: S
authors.lastname: Deveci
authors.forename: Inanc
authors.initials: I
authors.lastname: Guvenc
authors.forename: Nail
authors.initials: N
authors.lastname: Bulakbasi
mesh_terms: D003287:Contrast Media; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D017352:Echo-Planar Imaging; D005260:Female; D006801:Humans; D008107:Liver Diseases / Q000175:diagnosis*; D008113:Liver Neoplasms / Q000175:diagnosis; D008297:Male; D008536:Meglumine / Q000031:analogs & derivatives; D008875:Middle Aged; D009942:Organometallic Compounds; D012372:ROC Curve; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; C064572:gadobenic acid; D008536:Meglumine