Analysis of diffusion tensor imaging metrics for gliomas grading at 3 T.
OBJECTIVE
To assess the diagnostic accuracy of axial diffusivity (AD), radial diffusivity (RD), apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values derived from DTI for grading of glial tumors, and to estimate the correlation between DTI parameters and tumor grades.


METHODS
Seventy-eight patients with glial tumors underwent DTI. AD, RD, ADC and FA values of tumor, peritumoral edema and contralateral normal-appearing white matter (NAWM) and AD, RD, ADC and FA ratios: lowest average AD, RD, ADC and FA values in tumor or peritumoral edema to AD, RD, ADC and FA of NAWM were calculated. DTI parameters and tumor grades were analyzed statistically and with Pearson correlation. Receiver operating characteristic (ROC) curve analysis was also performed.


RESULTS
The differences in ADC, AD and RD tumor values, and ADC and RD tumor ratios were statistically significant between grades II and III, grades II and IV, and between grades II and III-IV. The AD tumor ratio differed significantly among all tumor grades. Tumor ADC, AD, RD and glial tumor grades were strongly correlated. In the ROC curve analysis, the area under the curve (AUC) of the parameter tumor ADC was the largest for distinguishing grade II from grades III to IV (98.5%), grade II from grade IV (98.9%) and grade II from grade III (97.0%).


CONCLUSIONS
ADC, RD and AD are useful DTI parameters for differentiation between low- and high-grade gliomas with a diagnostic accuracy of more than 90%. Our study revealed a good inverse correlation between ADC, RD, AD and WHO grades II-IV astrocytic tumors.
Section of Neuroradiology, Department of Radiology and Nuclear Medicine, Oslo University Hospital, Oslo, Norway. Electronic address: uxasea@ous-hf.no.
Andrés
A
Server
Vestre Viken Hospital Trust, Drammen, Norway. Electronic address: bjgrafe@vestreviken.no.
Bjørn A
BA
Graff
Department of Neurosurgery, Oslo University Hospital, Oslo, Norway. Electronic address: uxroos@ous-hf.no.
Roger
R
Josefsen
Interventional Centre, Oslo University Hospital, Oslo, Norway. Electronic address: uxdoto@ous-hf.no.
Tone E D
TE
Orheim
Section of Neuroradiology, Department of Radiology and Nuclear Medicine, Oslo University Hospital, Oslo, Norway. Electronic address: uxscti@ous-hf.no.
Till
T
Schellhorn
Interventional Centre, Oslo University Hospital, Oslo, Norway. Electronic address: wiben@ous-hf.no.
Wibeke
W
Nordhøy
Section of Neuroradiology, Department of Radiology and Nuclear Medicine, Oslo University Hospital, Oslo, Norway. Electronic address: uxpena@ous-hf.no.
Per H
PH
Nakstad
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D001932:Brain Neoplasms / Q000473:pathology*; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D005910:Glioma / Q000473:pathology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
Apparent diffusion coefficient; Axial diffusivity; Brain tumor; Diffusion tensor imaging; Fractional anisotropy; Radial diffusivity