RESUMO
Highly malignant gliomas have an infiltrating growth making it impossible to establish the exact limits of the lesion with magnetic resonance images after contrast medium administration because the peripheral component of the lesion does not enhance. On the contrary, cerebral metastases have an expansive growth and therefore lack a peripheral component beyond the enhanced area. In some cases the MR perfusional technique can demonstrate neoplastic tissue even with little damage to the brain-blood barrier and therefore with no enhancement. Our study aimed to estimate in which cases the MR perfusion technique will characterize peripheral neoplastic tissue that fails to enhance in gliomas in order to make a differential diagnosis between gliomas and metastases. We studied 60 tumours in 53 patients with MR perfusion and conventional sequences. We evaluated the presence of hyperperfused tissue in CBV maps outside the enhanced area after contrast administration and estimated the tumoral tissue CBV. None of the metastases (24 cases) had hyperperfused peritumoural tissue which was present instead in 22/36 gliomas (infiltrating aspect in CBV maps). Moreover all the gliomas with infiltrating aspect had CBV values of the solid component of the lesion higher than gliomas with a non infiltrating aspect with a threshold value between 4.4 and 6.3. It was therefore possible to characterize 22 gliomas with infiltrating aspect in the perfusion maps and with CBV values higher than the threshold value. In addition, 17 metastases with a non infiltrating aspect were characterized with CBV values higher than the threshold. Fourteen gliomas and seven metastases both with a non infiltrating aspect in the perfusion maps and with CBV values below the threshold were not characterized. In conclusion, MR perfusion succeeded in characterizing 39 lesions out of 60.