[Application of apparent diffusion coefficient and fractional anisotropy in identification of tumor component and grading of brain astrocytoma].
OBJECTIVE
To evaluate the value of apparent diffusion coefficient (ADC) and fractional anisotropy (FA) in identification of tumor element and grading of brain astrocytoma.


METHODS
Thirty-three patients with histologically confirmed astrocytoma underwent diffusion weighted imaging (DWI), diffusion tensor imaging (DTI), and conventional MRI before operation. The values of ADC and FA of different regions in the same tumor and of astrocytoma of different grades were measured and compared.


RESULTS
The ADC values of the tumor parenchyma, necrotic region, peritumoral edema region were (1.28 +/- 0.44), (1.97 +/- 0.53), and (1.74 +/- 0.47) respectively, all significantly higher than that of the corresponding normal brain tissues [(0.80 +/- 0.18), P = 0.009, P = 0.000, P = 0.000] with significantly differences between the tumor parenchyma and necrotic region and peritumoral edema region (both P < 0.05), however, there was not significant difference between the necrotic region and peritumoral edema region. The FA values of the tumor parenchyma, necrotic region, and peritumoral edema region were (0.18 +/- 0.07), (0.14 +/- 0.05), and (0.16 +/- 0.05) respectively, all significantly higher than that of the corresponding normal brain tissues [(0.58 +/- 0.10), all P = 0.000], without significant differences among the former 3 groups. There were no significant differences in the ADC and FA values among the tumors at different grades, however, there was a tendency of ADC to decrease and of FA to increase along the increase of grade of tumor, although not significantly.


CONCLUSIONS
ADC value plays an important part in distinguishing tumor components and determining tumor boundary, and plays a certain role in judging the grade of astrocytomas. FA value is vital to determine the tumor boundary, and has certain value in differentiating high-grade from low-grade astrocytomas.
Li
Min
M
Department of Medical Imaging, Affiliated Hospital of Nantong University, Nantong 226001, China.
Jia
Zhong-Zheng
ZZ
Gu
Hong-Mei
HM
Zhou
Xue-Jun
XJ
Tang
Le-Min
LM
D000293:Adolescent; D000328:Adult; D000368:Aged; D016880:Anisotropy; D001254:Astrocytoma / Q000473:pathology*; D001932:Brain Neoplasms / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging