title: Liver lesion conspicuity during real-time MR-guided radiofrequency applicator placement using spoiled gradient echo and balanced steady-state free precession imaging.
abstract: OBJECTIVE
  To retrospectively evaluate the conspicuity of liver lesions in a fluoroscopic spoiled gradient echo (GRE) and a balanced steady-state free precession (SSFP) magnetic resonance imaging (MRI) sequence.
  
  
  METHODS
  In all, 103 patients with hepatocellular carcinomas (HCC) (41) or liver metastases (67) were treated using MR-guided radiofrequency ablation in a wide-bore 1.5 T scanner. A multislice real-time spoiled GRE sequence allowing for a T1 weighting (T1W) and a balanced SSFP sequence allowing for a T2/T1W contrast were used for MR guidance. The contrast-to-noise-ratio (CNR) of the lesions was calculated and lesion conspicuity was assessed retrospectively (easily detectable / difficult to detect / not detectable).
  
  
  RESULTS
  HCC was easily detectable in 33/52% (GRE/SSFP), difficult to detect in 30/18%, and not detectable in 37/30% of the cases. Mean CNR varied widely (9.1 for GRE vs. 16.4 for SSFP). Liver metastases were easily detectable in 58/41% (GRE/SSFP), difficult to detect in 14/21%, and not detectable in 28/38% of the cases. Mean CNR for liver metastases was 11.5 (GRE) vs. 12.7 (SSFP). Twenty percent of all lesions could not be detected with either of the MR fluoroscopy sequences.
  
  
  CONCLUSIONS
  MR fluoroscopy using GRE and SSFP contrast enabled real-time detectability of 80% of the liver lesions.
authors.affiliation: Eberhard Karls University of Tübingen, Department of Diagnostic and Interventional Radiology, Tübingen, Germany.
authors.forename: Hansjörg
authors.initials: H
authors.lastname: Rempp
authors.forename: Henning
authors.initials: H
authors.lastname: Loh
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Hoffmann
authors.forename: Eva
authors.initials: E
authors.lastname: Rothgang
authors.forename: Li
authors.initials: L
authors.lastname: Pan
authors.forename: Claus D
authors.initials: CD
authors.lastname: Claussen
authors.forename: Stephan
authors.initials: S
authors.lastname: Clasen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D006528:Carcinoma, Hepatocellular / Q000473:pathology* / Q000601:surgery*; D017115:Catheter Ablation / Q000379:methods*; D003199:Computer Systems; D005260:Female; D006498:Hepatectomy / Q000379:methods; D006801:Humans; D008113:Liver Neoplasms / Q000473:pathology* / Q000601:surgery*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D025321:Surgery, Computer-Assisted / Q000379:methods*
keywords: MR fluoroscopy; MR-guided intervention; interventional MRI; radiofrequency ablation; real-time MR sequences; steady-state free precession sequence