Inclusion Criteria:

- Histologically confirmed primary high-grade astrocytoma, i.e. anaplastic astrocytoma
or glioblastoma multiforme.

- Have a WHO performance status 0-2 and be able to undergo outpatient treatment.

- Age ≥18 years.

- No pregnant or lactating patients can be included.

- Patients must have radiographically documented measurable disease postoperatively. At
least one tumor lesion must be unidimensionally measurable as follows:

- Tumor lesion > 10 mm on conventional MRI scan, T1-weighted series, after
intravenous (i.v.) gadolinium chelate contrast.

- All diagnostic radiology studies must be performed within 28 days prior to
registration.

- Absence of conditions making MRI scans impossible;

- Cardiac pacemaker

- Other ferromagnetic metal implants not authorised for use in MRI such as some
types of cerebral aneurysm clips

- Serious claustrophobia

- Obesity (> 300 lb., 140 Kg)

- Patients who are receiving corticosteroids have to receive stable or decreasing doses
for at least 14 days before entering the trial.

- No prior chemotherapy for high-grade astrocytoma

- Absence of opportunistic infections making temozolomide contraindicated.

- Minimum required laboratory data:

- Hematology:

- Absolute granulocytes > 1.0 x 10^9/L

- Platelets > 100 x 10^9/L

- Biochemistry:

- Bilirubin < 1.5 x upper normal limit

- INR < 1.5

- Serum creatinine <1.5 x upper normal limit

- Adequate cognitive function in order to give informed consent.

- Absence of any psychological, familial or sociological condition potentially
hampering compliance with the study protocol and follow-up schedule; those conditions
should be discussed with the patient before registration in the trial

- Before patient registration/randomization, written informed consent must be given
according to national and local regulations.

Exclusion Criteria:

- Lack of fulfillment of inclusion criteria.