Pulsed and oscillating gradient MRI for assessment of cell size and extracellular space (POMACE) in mouse gliomas.

TitlePulsed and oscillating gradient MRI for assessment of cell size and extracellular space (POMACE) in mouse gliomas.
Publication TypeJournal Article
Year of Publication2016
AuthorsReynaud O, Winters KVeronica, Hoang DMinh, Wadghiri YZaim, Novikov DS, Kim SGene
JournalNMR Biomed
Volume29
Issue10
Pagination1350-63
Date Published2016 10
ISSN1099-1492
KeywordsAnimals, Brain Neoplasms, Cell Line, Tumor, Cell Size, Computer Simulation, Extracellular Space, Feasibility Studies, Female, Glioma, Image Interpretation, Computer-Assisted, Magnetic Resonance Imaging, Mice, Mice, Inbred C57BL, Models, Biological, Oscillometry, Reproducibility of Results, Sensitivity and Specificity, Signal Processing, Computer-Assisted, Tumor Burden
Abstract

Solid tumor microstructure is related to the aggressiveness of the tumor, interstitial pressure and drug delivery pathways, which are closely associated with treatment response, metastatic spread and prognosis. In this study, we introduce a novel diffusion MRI data analysis framework, pulsed and oscillating gradient MRI for assessment of cell size and extracellular space (POMACE), and demonstrate its feasibility in a mouse tumor model. In vivo and ex vivo POMACE experiments were performed on mice bearing the GL261 murine glioma model (n = 8). Since the complete diffusion time dependence is in general non-analytical, the tumor microstructure was modeled in an appropriate time/frequency regime by impermeable spheres (radius Rcell , intracellular diffusivity Dics ) surrounded by extracellular space (ECS) (approximated by constant apparent diffusivity Decs in volume fraction ECS). POMACE parametric maps (ECS, Rcell , Dics , Decs ) were compared with conventional diffusion-weighted imaging metrics, electron microscopy (EM), alternative ECS determination based on effective medium theory (EMT), and optical microscopy performed on the same samples. It was shown that Decs can be approximated by its long time tortuosity limit in the range [1/(88 Hz)-31 ms]. ECS estimations (44 ± 7% in vivo and 54 ± 11% ex vivo) were in agreement with EMT-based ECS and literature on brain gliomas. Ex vivo, ECS maps correlated well with optical microscopy. Cell sizes (Rcell  = 4.8 ± 1.3 in vivo and 4.3 ± 1.4 µm ex vivo) were consistent with EM measurements (4.7 ± 1.8 µm). In conclusion, Rcell and ECS can be quantified and mapped in vivo and ex vivo in brain tumors using the proposed POMACE method. Our experimental results support the view that POMACE provides a way to interpret the frequency or time dependence of the diffusion coefficient in tumors in terms of objective biophysical parameters of neuronal tissue, which can be used for non-invasive monitoring of preclinical cancer studies and treatment efficacy. Copyright © 2016 John Wiley & Sons, Ltd.

DOI10.1002/nbm.3577
Alternate JournalNMR Biomed
PubMed ID27448059
PubMed Central IDPMC5035213
Grant ListP30 CA016087 / CA / NCI NIH HHS / United States
P41 EB017183 / EB / NIBIB NIH HHS / United States
R01 CA160620 / CA / NCI NIH HHS / United States
Related Institute: 
MRI Research Institute (MRIRI)

Weill Cornell Medicine
Department of Radiology
525 East 68th Street New York, NY 10065