title: A comparative study of apparent diffusion coefficient and intravoxel incoherent motion-derived parameters for the characterization of common solid hepatic tumors.
abstract: BACKGROUND
  The performance of diffusion-weighted imaging parameters for characterizing hepatic tumors is controversial.
  
  
  OBJECTIVE
  To compare the performances of apparent diffusion coefficient (ADC) and intravoxel incoherent motion (IVIM)-derived parameters, including the pure diffusion coefficient (D), perfusion coefficient (D*), and perfusion fraction (f), in the characterization of common solid hepatic tumors.
  
  
  METHODS
  Twelve healthy volunteers and 43 patients underwent free-breath diffusion-weighted magnetic resonance imaging (DW-MRI) of the liver using eight b values (10-800 s/mm(2)). Twelve regions of interest (ROIs) of normal liver tissue in healthy volunteers and 49 hepatic lesions (23 hepatocellular carcinomas [HCCs], 16 hemangiomas, and 10 metastases) were measured. Conventional ADC(0,500) and ADCtotal obtained by the mono-exponential model, as well as D, D*, and f were calculated. Student t-tests and receiver operating characteristic (ROC) analysis were also performed.
  
  
  RESULTS
  ADC(0,500), ADCtotal, and D were significantly lower in the malignant group ([1.48 ± 0.35] × 10(-3) mm(2)/s; [1.35 ± 0.30] × 10(-3) mm(2)/s; [1.18 ± 0.33] × 10(-3) mm(2)/s) compared to the hemangioma group ([2.74 ± 1.03] × 10(-3) mm(2)/s; [2.61 ± 0.81] × 10(-3) mm(2)/s; [1.97 ± 0.79] × 10(-3) mm(2)/s]. D* did not differ among multiple comparisons. For the area under the ROC curve (AUC-ROC), the maximum value was attained with ADCtotal (0.983) and was closely followed by ADC(0,500) (0.967), with lower values obtained for D (0.837), f (0.649), and D* (0.599). Statistically significant differences were found between the AUC-ROC of both ADCs (ADCtotal and ADC(0,500)) and D. There was no statistically significant difference between the AUC-ROC of ADCtotal and ADC(0,500).
  
  
  CONCLUSIONS
  ADCs showed superior diagnostic performance compared to IVIM-derived parameters in detecting differences between the malignant group and hemangioma group.
authors.affiliation: Radiology Department, Xiamen Second Hospital, Xiamen, Fujian, PR China.
authors.forename: Liuhong
authors.initials: L
authors.lastname: Zhu
authors.affiliation: Radiology Department, Xiamen Second Hospital, Xiamen, Fujian, PR China.
authors.forename: Qihua
authors.initials: Q
authors.lastname: Cheng
authors.affiliation: Radiology Department, Xiamen Second Hospital, Xiamen, Fujian, PR China.
authors.forename: Wenbin
authors.initials: W
authors.lastname: Luo
authors.affiliation: Department of Electronic Science, Magnetic Resonance Imaging Research Center, Xiamen University, Xiamen, PR China.
authors.forename: Lijun
authors.initials: L
authors.lastname: Bao
authors.affiliation: Radiology Department, Xiamen Second Hospital, Xiamen, Fujian, PR China guogangxm@163.com.
authors.forename: Gang
authors.initials: G
authors.lastname: Guo
mesh_terms: D000328:Adult; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008099:Liver / Q000473:pathology; D008113:Liver Neoplasms / Q000473:pathology*; D008297:Male; D009038:Motion; D012372:ROC Curve; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult
keywords: Intravoxel incoherent motion; common solid hepatic tumors; diffusion-weighted imaging