title: T1 ρ mapping for the evaluation of high intensity focused ultrasound tumor treatment.
abstract: OBJECTIVE
  This study was aimed to assess the effects of High Intensity Focused Ultrasound (HIFU) thermal ablation on tumor T1ρ .
  
  
  METHODS
  In vivo T1ρ measurements of murine tumors at various spin-lock amplitudes (B1 = 0-2000 Hz) were performed before (n = 13), directly after (n = 13) and 3 days (n = 7) after HIFU treatment. T2 maps were obtained from the measurements at B1 = 0 Hz.
  
  
  RESULTS
  Average tumor T1ρ distributions at the different experimental time points showed a shift toward lower T1ρ values after HIFU for all spin-lock amplitudes, which became larger with increasing spin-lock amplitude at 3 days after treatment. Statistical analysis confirmed a significant effect of spin-lock amplitude on the average change in T1ρ (ΔT1ρ ) as compared to baseline at 3 days after HIFU. At 3 days after treatment, ΔT1ρ values at B1 above 100 Hz were significantly lower (more negative) than at B1 = 0 Hz (T2 ).
  
  
  CONCLUSIONS
  Significant changes in tumor T1ρ were observed after HIFU treatment. These T1ρ changes were distinctly more pronounced than HIFU-induced changes in T2 . The results indicate that T1ρ imaging is sensitive to HIFU-induced tissue changes and may thus be a suitable MR method for the evaluation of HIFU treatment. Magn Reson Med 73:1593-1601, 2015. © 2014 Wiley Periodicals, Inc.
authors.affiliation: Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands; Center for Imaging Research and Education (CIRE), Eindhoven, The Netherlands.
authors.forename: Stefanie J C G
authors.initials: SJ
authors.lastname: Hectors
authors.forename: Rik P M
authors.initials: RP
authors.lastname: Moonen
authors.forename: Gustav J
authors.initials: GJ
authors.lastname: Strijkers
authors.forename: Klaas
authors.initials: K
authors.lastname: Nicolay
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000473:pathology* / Q000628:therapy*; D057086:High-Intensity Focused Ultrasound Ablation / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D025321:Surgery, Computer-Assisted / Q000379:methods*; D016896:Treatment Outcome
keywords: T1ρ; cancer treatment response; high intensity focused ultrasound; spin-lock