Sodium and proton diffusion MRI as biomarkers for early therapeutic response in subcutaneous tumors.
The ability to quantitate early effects of tumor therapeutic response using noninvasive imaging would have a major impact in clinical oncology. One area of active research interest is the ability to use MR techniques to detect subtle changes in tumor cellular density. In this study, sodium and proton diffusion MRI were compared for their ability to detect early cellular changes in tumors treated with a cytotoxic chemotherapy. Subcutaneous 9L gliosarcomas were treated with a single dose of 1,3-bis(2-chloroethyl)-1-nitrosourea. Both sodium and diffusion imaging modalities were able to detect changes in tumor cellularity as early as 2 days after treatment, which continued to evolve as increased signal intensities reached a maximum approximately 8 days posttreatment. Early changes in tumor sodium and apparent diffusion coefficient values were predictive of subsequent tumor shrinkage, which occurred approximately 10 days later. Overall, therapeutical induced changes in sodium and diffusion values were found to have similar dynamic and spatial changes. These findings suggest that these imaging modalities detected similar early cellular changes after treatment. The results of this study support the continued clinical testing of diffusion MRI for evaluation of early tumor treatment response and demonstrate the complementary insights of sodium MRI for oncology applications.
Department of Radiology, Center for Molecular Imaging, University of Michigan Medical School, Ann Arbor, MI 48109-0503, USA. vschepki@umich.edu
Victor D
VD
Schepkin
Thomas L
TL
Chenevert
Kyle
K
Kuszpit
Kuei C
KC
Lee
Charles R
CR
Meyer
Timothy D
TD
Johnson
Alnawaz
A
Rehemtulla
Brian D
BD
Ross
D000818:Animals; D018906:Antineoplastic Agents, Alkylating / Q000494:pharmacology*; D014408:Biomarkers, Tumor; D001932:Brain Neoplasms / Q000737:chemistry / Q000188:drug therapy*; D002330:Carmustine / Q000494:pharmacology*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D018316:Gliosarcoma / Q000737:chemistry / Q000188:drug therapy*; D021621:Imaging, Three-Dimensional; D008297:Male; D009368:Neoplasm Transplantation; D011522:Protons; D051381:Rats; D011916:Rats, Inbred F344; D012964:Sodium
D018906:Antineoplastic Agents, Alkylating; D014408:Biomarkers, Tumor; D011522:Protons; D012964:Sodium; D002330:Carmustine