Fig 1.
Average values for different tumor types and grades.
Boxplots of average rCBV, rCTH, and COV values for different tumor types and grades (bars show median values, boxes represent interquartile ranges). GBM: glioblastoma; AC3: astrocytoma grade 3; AC2+AC1: astrocytoma greade 2 and 1, respectively; ODG3: oligodendroglioma grade 3; ODG2: oligodendroglioma grade 2; HGG: high grade glioma; LGG: low grade glioma.
Fig 2.
Image examples of a high-grade and a low-grade glioma.
Contrast-enhanced T1, T2FLAIR, cerebral blood volume (CBV), capillary transit time heterogeneity (CTH), and coefficient of variance (COV) maps in a patient with (A) a glioblastoma and (B) an astrocytoma grade 2. The enhancing tumor and the peri-focal edema are outlined with black lines on the parameter maps. (A) The glioblastoma shows increased COV in the enhancing part and high CTH in the peri-tumoral edema, whereas (B) the astrocytoma grade 2 is characterized by low CBV, CTH, and COV.
Fig 3.
Scatterplots showing the very weak correlation of rCBV and rCTH in (A) the enhancing tumor (R2 = 0.01; p = 0.41) and (B) the peri-focal edema (R2 = 0.06; p = 0.05), suggesting that they provide different information. Mean values for each patient are plotted. High-grade gliomas are marked with blue, low-grade gliomas with red.
Table 1.
Average values for different glioma types and grades.
Fig 4.
Accuracy for differentiating high-grade from low-grade gliomas.
The area under the curve as a measure for diagnostic accuracy is represented by bar length. Accuracy is calculated for single parameters (rCBV, rCTH, and COV) as well as for combinations of predictors, measured in the enhancing tumor (in red), the peri-focal edema (in blue), and a combined enhancing tumor/edema region (in brown).
Fig 5.
Differentiation of high-grade from low-grade gliomas.
Receiver Operating Characteristic curves illustrating the diagnostic performance of rCBV (blue), rCTH (green), and combined rCBV / rCTH (red) mean values within the enhancing tumor and the peri-focal edema to discriminate high-grade from low-grade gliomas.
Table 2.
Results of the logistic regression differentiating high-grade from low-grade gliomas.
Fig 6.
Survival curves for high-grade glioma patients.
Time to progression and overall survival for all glioma and for high-grade glioma (HGG) cases are shown. Curves for patients with high mean rCBV, rCTH, and COV values in the enhancing tumor or in a combined region consisting of the enhancing part and the peri-tumoral edema are blue; curves for patients with low mean values are red. A p-value < 0.05 denotes significant difference between the two curves.