Quantitative apparent diffusion coefficients and T2 relaxation times in characterizing contrast enhancing brain tumors and regions of peritumoral edema.
OBJECTIVE
To investigate the potential value and relationship of in vivo quantification of apparent diffusion coefficients (ADCs) and T2 relaxation times for characterizing brain tumor cellularity and tumor-related edema.


METHODS
A total of 26 patients with newly diagnosed gliomas, meningiomas, or metastases underwent diffusion-weighted and six-echo multisection T2-preparation imaging. Regions of interest (ROIs) were drawn on conventional MR images to include tumor (as defined by contrast agent enhancement) and immediate and peripheral edema. Areas of necrosis were excluded. Median values of ADCs and T2 in the ROIs were calculated.


RESULTS
ADCs for gliomas were similar to those for meningiomas or metastases in all regions. Tumor T2 values for gliomas (159.5+/-30.6 msec) were significantly higher than those for meningiomas or metastases (125.0+/-31.1 msec; P=0.005). Immediate-edema T2 values for meningiomas or metastases (226.0+/-44.1 msec) were significantly higher than those for gliomas (203.5+/-32.8 msec; P=0.033). Peripheral-edema T2 values for gliomas (219.5+/-41.9 msec) were similar to those for meningiomas or metastases (202.5+/-26.5 msec; P=0.377). Both immediate- and peritumoral-edema ADCs and T2 values were significantly higher than those in tumor for both tumor types. ADCs and T2 values from all regions correlated significantly for gliomas (r=0.95; P<0.0001) and for meningiomas or metastases (r=0.81; P<0.0001).


CONCLUSIONS
The higher immediate-edema T2 values for nonglial tumors than for gliomas suggest tumor-related edema (vasogenic vs. infiltrated) can be further characterized by using T2 values. There were significant correlations between ADC and T2 values.
Oh
Joonmi
J
Center for Molecular and Functional Imaging, University of California, San Francisco, San Francisco, California 94107, USA. joonmi.oh@radiology.ucsf.edu
Cha
Soonmee
S
Aiken
Ashley H
AH
Han
Eric T
ET
Crane
Jason C
JC
Stainsby
Jeffrey A
JA
Wright
Graham A
GA
Dillon
William P
WP
Nelson
Sarah J
SJ
D000328:Adult; D000368:Aged; D001929:Brain Edema / Q000473:pathology*; D001932:Brain Neoplasms / Q000473:pathology*; D003287:Contrast Media; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D019786:Gadolinium DTPA; D005910:Glioma / Q000473:pathology; D006801:Humans; D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted; D008297:Male; D008579:Meningioma / Q000473:pathology; D008875:Middle Aged
D003287:Contrast Media; D019786:Gadolinium DTPA