Comparision of PET/CT and difusion / perfusion weighted magnetic resonance imaging findings in malignant brain tumors

In this study, our aim was to determine if there was a relationship between the metabolic activity obtained from 18F FDG PET imaging (SUVmax) and diffusion coefficient (ADC) in diffusion weighted magnetic resonance imaging (DW-MRI) and relative cerebral blood volume (rCBV) obtained from perfusion magnetic resonance imaging in malignant brain tumors; to investigate the contribution of FDG PET imaging in differentiating grade 4 glioblastoma from metastatic cerebral mass lesions. A retrospective analysis was performed in 20 cases, 9 male and 11 female, who presented to Akdeniz University Medical Faculty Hospital Neurosurgery clinic with intracranial mass lesion diagnosis/pre-diagnosis. Patients who had conventional MR and FDG PET/CT images were included in the study. Patients who were operated previously, however, had no recurrence or residual mass in subsequent examinations and patients with extra axially located mass lesions were excluded from the study. A statistically significant negative correlation between the ADC value of the primary lesion and the ratio of metabolic activity in the late images to the metabolic activity of contralateral cortex (GSUV/ GSUVK) was determined (p<0.05, r =-0.52). Also, a statistically significant negative correlation was found between the perfusion of primary tumor (rCBV) and the percentage changes in SUVmax values of the mass in the late images (GSUV- ESUV/100* ESUV) (p<0.01, r = -0.63). Besides these, it was observed that late imaging has a diagnostic value in differentiating grade 4 glioblastoma from metastatic cerebral mass lesions (100% sensitivity, 75% specifity). According to the results obtained from our study, FDG PET provides an additional contribution to intracranial mass lesion diagnosis, and we believe that specially late imaging should be performed in brain lesions