Results
Patients’ demographics and clinical characteristics are presented in Table 2. The mean age of the patients at diagnosis was 58.5 ± 11.6 years and ranged from 33 to 75 years. Four patients with cerebral metastases were excluded from the perfusion analysis as their perfusion physiology differed depending on the primary tumour characteristics. Furthermore, no comparisons between the two patients with inflammatory lesions were carried out because of the heterogeneity and the limited number of patients in this subgroup.
Table 2 Patients’ demographics and clinical characteristics
n %
Male 30 61.2
Female 19 38.8
High-grade gliomas 31 63.3
Lymphomas 8 16.3
Low-grade gliomas 4 8.15
Metastases 4 8.15
Infectious tumour-like lesions 2 4.1
Data from 43 patients were finally analysed. Patients were classified into three histopathological subgroups (low-grade gliomas, high-grade gliomas, lymphomas).

Comparison of perfusion parameters between affected and normal cerebral parenchyma
The mean values for K Trans, CBV and CBF values for the study subgroups and the comparisons with the control healthy parenchyma are summarised in Table 3. No significant difference in the perfusion parameters was found between areas of low-grade gliomas and normal cerebral parenchyma (p > 0.05 for all analysed perfusion parameters). High-grade gliomas, on the other hand, demonstrated significantly higher values of all perfusion parameters compared with normal cerebral parenchyma (p < 0.0001 for KTrans, p < 0.0001 for CBV and p = 0.0002 for CBF). Lymphomas displayed significantly increased mean permeability values compared with unaffected cerebral parenchyma (p = 0.0078 for K Trans), whereas no significant difference was noted between the mean CBV and CBF values (p = 0.55 for CBV, p = 0.25 for CBF).
Table 3 Comparison of perfusion parameters between affected and normal cerebral parenchyma. Values are expressed as mean ± SD
Histopathological  K Trans  p a CBV  p a CBF  p a
subgroup (p) (ml/100 ml/min) (ml/100 ml) (ml/100 ml/min)
Lesion Control Lesion Control Lesion Control
Low-grade gliomas (4) 3.73 ± 5.35 1.66 ± 1.79 0.25 3.28 ± 0.46 2.96 ± 0.42 0.38 62.28 ± 16.91 65.80 ± 5.50 0.88
High-grade gliomas (31) 6.58 ± 3.68 0.86 ± 0.79 <0.0001 6.03 ± 2.18 3.22 ± 0.42 <0.0001 97.63 ± 41.17 64.45 ± 7.84 0.0002
Lymphomas (8) 11.96 ± 10.66 1.31 ± 1.79 0.0078 3.79 ± 1.95 3.14 ± 0.42 0.55 82.79 ± 40.03 64.87 ± 9.61 0.25
a p compared with healthy parenchyma values (control) using Wilcoxon test

Comparison of perfusion parameters between different histopathological subgroups
Low-grade gliomas were excluded from the comparisons among the histopathological subgroups because their low number precluded an efficient statistical analysis. Figures 1, 2 and 3 show the comparison between high-grade gliomas and lymphomas (Mann-Whitney U-test): whereas no statistical difference was found for CBF (p = 0.3567) and K Trans (p = 0.1394), high-grade gliomas showed a significant elevation of CBV in comparison to lymphomas (p = 0.0078). However, higher mean permeability values, though not statistically significant, were observed in lymphomas in comparison with high-grade gliomas.
Fig. 1 Comparison of high-grade gliomas (tumour type 2) and lymphomas (tumour type 3): Mann-Whitney U-test showed significant elevation of CBV within high-grade gliomas compared with lymphomas (p = 0.0078)
Fig. 2 Comparison of high-grade gliomas (tumour type 2) and lymphomas (tumour type 3): Mann-Whitney U-test showed no significant difference in CBF within the tumour tissue (p = 0.3567)
Fig. 3 Comparison of high-grade gliomas (tumour type 2) and lymphomas (tumour type 3): Mann-Whitney U-test showed no significant difference in K Trans within the tumour tissue (p = 0.1394)