Candidate biomarkers of extravascular extracellular space: a direct comparison of apparent diffusion coefficient and dynamic contrast-enhanced MR imaging--derived measurement of the volume of the extravascular extracellular space in glioblastoma multiforme.
OBJECTIVE
ADC measurements have been shown to have an inverse relationship with tumor cell density. DCE-MR imaging modeling techniques can produce a measurement of the v(e), which would also be expected to have an inverse relationship with cell density. The objective of this study was to test the hypothesis that areas of increased cellularity, and therefore low ADC, would be expected to have a small EES (low v(e)).


METHODS
Nineteen patients with GBM were recruited. All imaging was performed before surgery on a 3T MR imaging scanner. Imaging included diffusion tensor imaging, T1-weighted DCE-MR imaging, and anatomic sequences. Tumor VOIs were defined on the anatomic images and modified to contain only enhancing voxels. Parametric maps of ADC and v(e) were generated. Statistical analysis of ADC and v(e) was performed on both a voxel-by-voxel basis and comparison of median values.


RESULTS
No correlation was demonstrated between ADC and v(e) in either a voxel-by-voxel analysis or comparison of median values (P = .124).


CONCLUSIONS
This study failed to demonstrate a correlation between ADC and v(e). This is important because it suggests that though the mechanisms underlying these parameters are theoretically similar, they actually reflect different aspects of tumor microenvironment. Consequently ADC and v(e) should be considered to provide independent information about the properties of the EES.
Imaging Science and Biomedical Engineering Department, School of Cancer and Imaging Sciences, University of Manchester, Withington, Manchester, United Kingdom. samantha.mills@manchester.ac.uk
S J
SJ
Mills
C
C
Soh
C J
CJ
Rose
S
S
Cheung
S
S
Zhao
G J M
GJ
Parker
A
A
Jackson
D000293:Adolescent; D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000378:metabolism; D001932:Brain Neoplasms / Q000378:metabolism* / Q000473:pathology*; D002452:Cell Count; D003287:Contrast Media; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005110:Extracellular Space / Q000378:metabolism; D005260:Female; D019786:Gadolinium DTPA; D005909:Glioblastoma / Q000378:metabolism* / Q000473:pathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D055815:Young Adult
D015415:Biomarkers; D003287:Contrast Media; C064925:gadodiamide; D019786:Gadolinium DTPA