title: Can volumetric ADC measurement help predict response to Y90 radioembolization in HCC?
abstract: OBJECTIVE
  To compare changes in RECIST, anatomical volume, mRECIST, and volumetric diffusion-weighted Imaging parameters (3D apparent diffusion coefficient (ADC) measurements), with pathological analysis of hepatocellular carcinoma (HCC) treated by (90)Yttrium radioembolization (Y90).
  
  
  METHODS
  21 patients were treated by Y90 as a sole treatment modality for solitary, >2 cm HCC that underwent liver transplantation. MRI at baseline, 1 and 3 months post-Y90, and tumor pathological findings on explants were reviewed in all patients.
  
  
  RESULTS
  Compared to baseline (RECIST/volume: 3.6 cm/17.7 cm(3)), RECIST and volume were not modified after Y90 (1 month, p = 0.28/0.09 RECIST/tumor volume; 3 months, p = 0.28/0.54). In contrast, mRECIST (3.3-1.4 cm, p < 0.001), mean ADC (0.185-1.093 mm(2)/s × 10(-3), p = 0.04), and ADC standard deviation (STD) (0.041-0.201 mm(2)/s × 10(-3), p = 0.0496) changed as earlier as 1 month post-Y90. ADC STD % change was higher in ADC responding lesions than non-responding lesions at 1 month (p = 0.002) and 3 months (p = 0.008). All lesions exhibited necrosis on pathological analysis (11 partially viable, 10 complete pathological necrosis (CPN)) but no imaging criterion was able to predict CPN. mRECIST (±ADC) at 1 (κ ± ADC = 0.08/0.06) or 3 months (κ = -0.06/-0.06) were poor predictors of pathological response.
  
  
  CONCLUSIONS
  As soon as 1 month post-treatment, mRECIST and volumetric ADC performed better than traditional size RECIST or volumetric parameters in detecting imaging response to Y90; however, CPN cannot be predicted by any criteria. Improvements in methodologies to assess response and identification of better surrogates are awaited.
authors.affiliation: Section of Interventional Radiology and Division of Interventional Oncology, Department of Radiology, Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, IL, USA, mvouche@ulb.ac.be.
authors.forename: Michael
authors.initials: M
authors.lastname: Vouche
authors.forename: Riad
authors.initials: R
authors.lastname: Salem
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Lewandowski
authors.forename: Frank H
authors.initials: FH
authors.lastname: Miller
mesh_terms: D006528:Carcinoma, Hepatocellular / Q000473:pathology* / Q000532:radiotherapy*; D038524:Diffusion Magnetic Resonance Imaging; D004621:Embolization, Therapeutic; D005260:Female; D006801:Humans; D008099:Liver / Q000473:pathology / Q000528:radiation effects; D008113:Liver Neoplasms / Q000473:pathology* / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D016896:Treatment Outcome; D015021:Yttrium Radioisotopes / Q000627:therapeutic use*
chemical_list: D015021:Yttrium Radioisotopes