Potentialities of PET in Diagnosis of a Prolonged Growth of Cerebral Tumors and Assessment of Treatment Efficacy

Kostenikov N., Tyutin L., Fadeev N., Vinogradov V., Zhabina R., Katrashov .

Central Research Radiological Institute, Saint Petersburg, Russia

 

The research goal was to assess potentialities of PET with 11C-sodium butyrate (11C-SB) and 18F-fluordeoxyglucose (18F-FDG) in diagnosis of a prolonged growth of cerebral tumors and estimation of treatment efficacy.

Material and Methods. PET-scanning (Ecat Exact HR+, Siemens) was carried out in 45 cases with a suspected prolonged growth of cerebral tumors. It was done twice in a postoperative period, i.e. before and after a course of irradiation and polychemotherapy. Dynamic scanning started immediately after I/V administration of 650 MBq of 11C-SB. Static scanning was carried out 30 min after injection of 185 MBq of 18F-FDG. The activity of both radiopreparations was determined on the basis of the T/NT ratio. Vascularization, velocity of capture and utilization of 11C-SB within a tumor were estimated by the activity-time curve. Malignant and benign tumors were present in 27 and 9 out of 45 cases respectively. There was no prolonged growth of neoplasms in 9 patients.

Results. T/NT in PET with 18F-FDG was higher than 0.8 in 26 cases with a prolonged growth of malignant tumors. T/NT did not exceed 0.4 in 7 patients with no signs of a prolonged growth. T/NT reduction was watched during radiation therapy in studies, carried out with both radiopreparations. T/NT reduction up to 0.4 and less, observed in a tumor zone, was a criterion of healing. Vascularization, velocity of capture and utilization of fatty acids within a tumor were reliably lower in effective treatment.

Conclusion. PET with 18F-FDG allows to reveal a prolonged growth of tumors and to assess treatment efficacy. Dynamic studies with 11C-SB give a unique information on metabolic changes within tumors, taking place during treatment, and are the earliest criterion for determining its effect.