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Water diffusion in a rat glioma during ganciclovir‐thymidine kinase gene therapy‐induced programmed cell death in vivo: Correlation with cell density
Author(s) -
Valonen Piia K.,
Lehtimäki Kimmo K.,
Väisänen Tuula H.,
Kettunen Mikko I.,
Gröhn Olli H.J.,
YläHerttuala Seppo,
Kauppinen Risto A.
Publication year - 2004
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/jmri.20026
Subject(s) - effective diffusion coefficient , in vivo , chemistry , glioma , diffusion mri , programmed cell death , nuclear magnetic resonance , diffusion , thymidine kinase , apoptosis , pathology , magnetic resonance imaging , biology , medicine , cancer research , physics , immunology , biochemistry , virus , microbiology and biotechnology , radiology , herpes simplex virus , thermodynamics
Purpose To study the characteristics of diffusion magnetic resonance imaging (MRI) contrast in a rat brain BT4C glioma during progression of ganciclovir (GCV)‐thymidine kinase gene therapy‐induced programmed cell death (PCD) in vivo. Materials and Methods The trace of the diffusion tensor (Dav = 1/3Trace), T 2 , and spin density were determined by MRI and the apparent diffusion coefficient (ADC) of water by diffusion nuclear MR (NMR) spectroscopy using largely varying b values and diffusion times (t D ) at 4.7 T. Cell count and apoptotic cells were quantified by histological means. Results Decline in cell count was strongly associated with increase in both D av and T 2 . Spin density ratio between tumor and contralateral parietal cortex increased with a very similar time course as D av and T 2 , indicating net water gain into the eradicating tumor. Diffusion spectroscopy showed a nonmonoexponential signal decay at all t D values ranging from 14–192 msec. During PCD, the ADC of the component yielding fast diffusion coefficient (D 1 ), as acquired with t D ≥ 47 msec, increased with kinetics similar to those of D av (t D = 4.8 msec). The fractional size of D 1 increased by 10% to 15% throughout the entire t D range. Apparent water residence time of the slow diffusion component, D 2 , shortened from a value of 38.3 ± 1.7 msec on day 0 to 33.4 ± 0.5 msec by day 8. Conclusion The present results show that reduced cell density and increased water content, leading to altered water microenvironment, are associated with increased water diffusion coefficient in eradicating gliomas as a result of PCD. J. Magn. Reson. Imaging 2004;19:389–396. © 2004 Wiley‐Liss, Inc.