Effect of hydrophilic components of the extracellular matrix on quantifiable diffusion-weighted imaging of human gliomas: preliminary results of correlating apparent diffusion coefficient values and hyaluronan expression level.
OBJECTIVE
The purpose of this study was to evaluate the relationship between apparent diffusion coefficient (ADC) measured by MR imaging and the level of immunohistochemical expression of hyaluronan or hyaluronic acid as one of the main hydrophilic components of the extracellular matrix in brain glial tumors.


METHODS
Nineteen patients with primary glial brain tumors were included in the study. Mean ADC values were calculated in all tumors and were normalized with the ADC values of the contralateral normal-appearing brain ratios. All tumors underwent surgical resection, and the histologic diagnosis was based on the analysis of the surgical specimen. Mean values of the labeling index of hyaluronan (LI-HA) were calculated to determine quantifiably the histochemical expression of hyaluronan in the tumor. The mean ADC values and the mean ADC ratios (ADC(ratio)) of the tumors were then correlated to the mean values of the LI-HA.


RESULTS
The mean ADC (93 x 10(-5) mm(2)/sec) and the mean ADC(ratio) (1.25) of the high-grade glial tumors were significantly lower than the mean ADC (123 x 10(-5) mm/sec) and the mean ADC(ratio) (1.64) of the low-grade glial tumors (p < 0.01). The mean LI-HA (72.8%) was also significantly lower in the high-grade gliomas than the mean LI-HA (93.4%) in the low-grade gliomas (p < 0.001). A positive correlation was found between mean ADC values and the mean LI-HA (tau = 0.35, p < 0.05) and also between the mean ADC(ratio) and the mean LI-HA (tau = 0.33, p < 0.05).


CONCLUSIONS
Hyaluronan as one of the main hydrophilic components of the extracellular matrix in gliomas likely contributes to differences in the ADC values between high- and low-grade glial tumors.
Sadeghi
Niloufar
N
Department of Radiology, Hôpital Erasme, Université Libre de Bruxelles, 808, Route de Lennik, 1070, Brussels, Belgium.
Camby
Isabelle
I
Goldman
Serge
S
Gabius
Hans-Joachim
HJ
Balériaux
Danielle
D
Salmon
Isabelle
I
Decaesteckere
Christine
C
Kiss
Robert
R
Metens
Thierry
T
D001921:Brain / Q000378:metabolism / Q000473:pathology; D001932:Brain Neoplasms / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D038524:Diffusion Magnetic Resonance Imaging; D005109:Extracellular Matrix / Q000378:metabolism*; D005260:Female; D005910:Glioma / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D006801:Humans; D006820:Hyaluronic Acid / Q000378:metabolism*; D008297:Male; D008875:Middle Aged
D006820:Hyaluronic Acid