title: Glioma cell density in a rat gene therapy model gauged by water relaxation rate along a fictitious magnetic field.
abstract: Longitudinal and transverse rotating-frame relaxation time constants, T(1) (ρ) and T(2) (ρ) , have previously been successfully applied to detect gene therapy responses and acute stroke in animal models. Those experiments were performed with continuous-wave irradiation or with frequency-modulated pulses operating in an adiabatic regime. The technique called Relaxation Along a Fictitious Field (RAFF) is a recent extension of frequency-modulated rotating-frame relaxation methods. In RAFF, spin locking takes place along a fictitious magnetic field, and the decay rate is a function of both T(1ρ) and T(2ρ) processes. In this work, the time constant characterizing water relaxation with RAFF (T(RAFF) ) was evaluated for its utility as a marker of response to gene therapy in a rat glioma model. To investigate the sensitivity to early treatment response, we measured several rotating-frame and free-precession relaxation time constants and the water apparent diffusion coefficients, and these were compared with histological cell counts in 8 days of treated and control groups of animals. T(RAFF) was the only parameter exhibiting significant association with cell density in three different tumor regions (border, intermediate, and core tissues). These results indicate that T(RAFF) may provide a marker to identify tumors responding to treatment.
authors: Department of Biotechnology and Molecular Medicine A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland. timo.liimatainen@uef.fi
authors: Timo
authors: T
authors: Liimatainen
authors: Alejandra
authors: A
authors: Sierra
authors: Timothy
authors: T
authors: Hanson
authors: Dennis J
authors: DJ
authors: Sorce
authors: Seppo
authors: S
authors: Ylä-Herttuala
authors: Michael
authors: M
authors: Garwood
authors: Shalom
authors: S
authors: Michaeli
authors: Olli
authors: O
authors: Gröhn
mesh_terms: D000818:Animals; D001932:Brain Neoplasms / Q000235:genetics / Q000473:pathology* / Q000628:therapy*; D002452:Cell Count; D045744:Cell Line, Tumor; D004574:Electromagnetic Fields; D005260:Female; D015316:Genetic Therapy / Q000379:methods*; D005910:Glioma / Q000235:genetics / Q000473:pathology* / Q000628:therapy*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D051381:Rats; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome; D014867:Water / Q000032:analysis
chemical_list: D014867:Water