title: Characterization of Liver Tumors by Diffusion-Weighted Imaging: Comparison of Diagnostic Performance Using the Mean and Minimum Apparent Diffusion Coefficient.
abstract: OBJECTIVE
  To determine the minimum apparent diffusion coefficient (ADC(min)) values of benign and malignant hepatic lesions based on diffusion-weighted imaging and to compare the diagnostic performance of ADC(min) and mean ADC (ADC(mean)) values for differentiating between benign and malignant tumors of the liver.
  
  
  METHODS
  We retrospectively subjected 240 patients with 195 malignant (hepatocellular carcinoma [HCC], n = 137; metastases, n = 44; cholangiocellular carcinoma [CCC], n = 14) and 45 benign tumors (hemangiomas, n = 37; focal nodular hyperplasia [FNH], n = 8). Both ADC(mean) and ADC(min) were evaluated independently by 2 readers, the sensitivity and specificity for the detection of malignancy were calculated, and receiver operating characteristic (ROC) curves were generated. To determine interobserver agreement, we calculated the Pearson correlation coefficient.
  
  
  RESULTS
  Mean ADC (×10 mm/s) was 1.19 for malignant (HCC, 1.15; metastasis, 1.23; CCC, 1.51) and 2.01 for benign tumors (hemangioma, 2.09; FNH, 1.52; P < 0.001). Minimum ADC was 0.81 for malignant (HCC, 0.79; metastasis, 0.81; CCC, 0.91) and 1.62 for benign tumors (hemangioma, 1.66; FNH, 1.28; P < 0.001). The sensitivity, specificity, and the calculated area under the ROC curve for diagnosing malignant lesions were 86.2%, 86.7%, and 0.942 (reader 1) and 88.7%, 88.9%, and 0.939 (reader 2) for ADC(mean); they were of 92.3%, 97.8%, and 0.984 (reader 1) and 94.9%, 97.8%, and 0.983 (reader 2) for ADC(min).
  
  
  CONCLUSIONS
  Mean ADC and ADC(min) were valuable for differentiating between malignant and benign hepatic lesions. The area under the ROC curve of ADC(min) was significant higher than that of ADC(mean).
authors.affiliation: From the Department of Diagnostic Radiology, Graduate School of Life Sciences, Kumamoto University, Honjo, Kumamoto, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Namimoto
authors.forename: Masataka
authors.initials: M
authors.lastname: Nakagawa
authors.forename: Yuuki
authors.initials: Y
authors.lastname: Kizaki
authors.forename: Ryo
authors.initials: R
authors.lastname: Itatani
authors.forename: Masafumi
authors.initials: M
authors.lastname: Kidoh
authors.forename: Daisuke
authors.initials: D
authors.lastname: Utsunomiya
authors.forename: Seitaro
authors.initials: S
authors.lastname: Oda
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Yamashita
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D003287:Contrast Media; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D007089:Image Enhancement; D007090:Image Interpretation, Computer-Assisted; D008099:Liver / Q000473:pathology; D008113:Liver Neoplasms / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D003287:Contrast Media; C073590:gadolinium ethoxybenzyl DTPA; D019786:Gadolinium DTPA