title: Microvascular invasion in small hepatocellular carcinoma: is it predictable with preoperative diffusion-weighted imaging?
abstract: OBJECTIVE
  The presence of microvascular invasion (MVI) is an independent risk factor affecting recurrence-free survival following surgical treatment for small hepatocellular carcinoma (HCC). Our aim in this study was to investigate whether diffusion-weighted imaging (DWI) could be useful in predicting MVI for small HCC.
  
  
  METHODS
  Breath-hold DWI (b-value 0, 500 s/mm(2) ) and gadopentate dimeglumine-enhanced dynamic imaging of preoperative magnetic resonance imaging of 109 surgically proven small HCCs from 92 patients were retrospectively analyzed. The signal intensity ratio on DWI and apparent diffusion coefficients (ADCs) for lesions were quantitatively measured. Signal intensity ratio and ADC of DWI, tumor size, tumor shape, tumor capsule, peritumoral enhancement on arterial phase images, and dynamic enhancement pattern were analyzed as radiological parameters reflecting MVI and were compared with histopathological references. The chi-square test, Fisher's exact test, Mann-Whitney U test, and the independent t-test were used for univariate analysis. To identify the independent predictors of MVI among these radiological parameters and to evaluate their diagnostic performance, multivariate logistic regression analysis and receiver operating characteristic curve analysis were performed, respectively.
  
  
  RESULTS
  A univariate analysis showed that a lower ADC value (P = 0.005) and irregular circumferential enhancement (P = 0.020) showed statistically significant associations with MVI. A multiple logistic regression analysis showed that the ADC value and irregular circumferential enhancement were independent predictors of MVI. With a cut-off of 1.227 × 10(-3)  mm(2) /s, the ADC value provided a sensitivity of 66.7% and a specificity of 78.6% in the prediction of MVI with an odds ratio of 7.63 (P < 0.01).
  
  
  CONCLUSIONS
  Lower ADC values (< 1.227 × 10(-3)  mm(2) /s) on DWI with b-value of 0.500 s/mm(2) can be a useful preoperative predictor of MVI for small HCCs.
authors.affiliation: Department of Radiology, Shanghai Institute of Medical Imaging, Shanghai, China.
authors.forename: Pengju
authors.initials: P
authors.lastname: Xu
authors.forename: Mengsu
authors.initials: M
authors.lastname: Zeng
authors.forename: Kai
authors.initials: K
authors.lastname: Liu
authors.forename: Yan
authors.initials: Y
authors.lastname: Shan
authors.forename: Chen
authors.initials: C
authors.lastname: Xu
authors.forename: Jiang
authors.initials: J
authors.lastname: Lin
mesh_terms: D000328:Adult; D000368:Aged; D006528:Carcinoma, Hepatocellular / Q000098:blood supply* / Q000175:diagnosis / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D005544:Forecasting; D006801:Humans; D008113:Liver Neoplasms / Q000098:blood supply* / Q000175:diagnosis / Q000473:pathology*; D016015:Logistic Models; D008297:Male; D055806:Microvessels / Q000473:pathology*; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009389:Neovascularization, Pathologic; D012189:Retrospective Studies
keywords: apparent diffusion coefficient; diffusion-weighted MRI; hepatocellular carcinoma; magnetic resonance imaging; microvascular invasion