title: MR-PET evaluation of 1-month post-ablation therapy for hepatocellular carcinoma: preliminary observations.
abstract: OBJECTIVE
  The purpose of the study was to evaluate the feasibility and protocol optimization of whole-body hybrid MR-PET system performed 1-month after post-locoregional thermoablative procedures for hepatocellular carcinomas (HCCs).
  
  
  METHODS
  Eight patients (6 men and 2 women; mean age, 56.6 ± 5.5 years) with 9 ablated HCCs constituted our study population. Three readers interpreted the studies to determine the presence or absence of residual malignancy. Two readers independently assessed the fused MR-PET images to compare registration accuracy of two types of T2-weighted (triggered T2 half-Fourier acquisition single-shot turbo spin-echo and turbo spin-echo) and T1-weighted [Cartesian and radial 3D gradient echo (GRE)]. Image quality evaluation of both 3D-GRE T1-weighted sequences was evaluated. Kappa statistics were used to measure inter-observer agreement. Non-parametric Kruskal-Wallis and Wilcoxon signed-rank tests were used for qualitative data analysis.
  
  
  RESULTS
  Definite residual tumor was observed in 3/9 ablations; two were PET positive. All residual tumors were isovascular on MRI. Radial 3D-GRE demonstrated significantly superior MR-PET subjective co-registration in comparison with the remaining sequences and showed a non-significant trend toward higher image quality scores than Cartesian GRE.
  
  
  CONCLUSIONS
  Whole-body hybrid MR-PET is feasible as a part of 1-month follow-up post-locoregional thermoablative treatment for HCC. Radial 3D-GRE offers improved co-registration with PET data, with overall good image quality.
authors.affiliation: Department of Radiology, University Of North Carolina at Chapel Hill, CB 7510, 2001 Old Clinic Bldg., Chapel Hill, NC, 7599-7510, USA.
authors.forename: Miguel
authors.initials: M
authors.lastname: Ramalho
authors.forename: Mamdoh
authors.initials: M
authors.lastname: AlObaidy
authors.forename: Lauren M
authors.initials: LM
authors.lastname: Burke
authors.forename: Brian M
authors.initials: BM
authors.lastname: Dale
authors.forename: David A
authors.initials: DA
authors.lastname: Gerber
authors.forename: Terence Z
authors.initials: TZ
authors.lastname: Wong
authors.forename: Richard C
authors.initials: RC
authors.lastname: Semelka
mesh_terms: D006528:Carcinoma, Hepatocellular / Q000601:surgery*; D017115:Catheter Ablation; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008099:Liver / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D008113:Liver Neoplasms / Q000601:surgery*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D015588:Observer Variation; D049268:Positron-Emission Tomography; D011183:Postoperative Complications / Q000175:diagnosis*; D011184:Postoperative Period; D015203:Reproducibility of Results; D016896:Treatment Outcome; D051598:Whole Body Imaging