title: Self-gated bSSFP sequences to detect iron-labeled cancer cells and/or metastases in vivo in mouse liver at 7 Tesla.
abstract: BACKGROUND
  To develop and evaluate three-dimensional (3D) self-gated balanced steady state free precession (bSSFP) imaging at high magnetic fields to track iron-labeled cells and metastases in murine abdomens.
  
  
  METHODS
  Mice were injected intravenously with iron-labeled melanoma cells and imaged at 7 Tesla (T). Respiration peaks were identified using Free Induction Decay acquired immediately after the radiofrequency pulse. Respiration-corrupted k-space lines were deleted. Four images were acquired to reconstruct final images using the Sum-Of-Square technique. Image sharpness, metastasis contrast and iron-labeled cell detection with SG-bSSFP sequence (acquired with echo time [TE] = 3 ms or TE = 6 ms) were compared with standard methods (gradient echo (GRE) and RARE).
  
  
  RESULTS
  After reconstruction, the 3D SG-bSSFP images were 75-80% sharper, free from banding (75% liver signal-to-noise ratio recovery) and respiratory motion (26-42% improvement in signal homogeneity) artifacts. Metastasis contrast was twice higher on SG-bSSFP with TE = 3 ms than on RARE images. Iron-labeled cells and metastases were simultaneously detected on SG-bSSFP images with TE = 6 ms, with similar void intensity and tumor contrast to GRE and RARE, respectively. Halving acquisition time preserved iron sensitivity and metastasis contrast, allowing for 3D abdomen imaging in 13 min (TE = 3 ms) or 26 min (TE = 6 ms).
  
  
  CONCLUSIONS
  Combining a self-gating technique with bSSFP sequences at 7T provides high-resolution 3D artifact-free abdominal images of small animals.
authors.affiliation: Centre de Résonance Magnétique des Systèmes Biologiques, UMR5536, CNRS-Université Bordeaux, France.
authors.forename: Emeline J
authors.initials: EJ
authors.lastname: Ribot
authors.forename: Tom J
authors.initials: TJ
authors.lastname: Duriez
authors.forename: Aurélien J
authors.initials: AJ
authors.lastname: Trotier
authors.forename: Eric
authors.initials: E
authors.lastname: Thiaudiere
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Franconi
authors.forename: Sylvain
authors.initials: S
authors.lastname: Miraux
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D058948:Cell Tracking / Q000379:methods; D003287:Contrast Media; D005260:Female; D005290:Ferric Compounds; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008113:Liver Neoplasms / Q000473:pathology* / Q000556:secondary*; D008545:Melanoma / Q000473:pathology* / Q000556:secondary*; D051379:Mice; D008810:Mice, Inbred C57BL; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013194:Staining and Labeling / Q000379:methods
chemical_list: D003287:Contrast Media; D005290:Ferric Compounds; C000499:ferric oxide
keywords: 7T; bSSFP; metastasis; mouse abdomen; self-gating