(68Ga)-EDTA positron emission tomography in the diagnosis of brain tumors

Fifty-two patients with active brain tumors and 8 patients with brain lesions from surgical treatment and/or radio- and/or chemotherapy of their brain tumors were examined by positron emission tomography (PET) using (68Ga)-EDTA in addition to conventional X-ray computed tomography (XCT). All patients with active brain tumors showed abnormal uptake of radioactivity in the tumor region, while all treated patients had normal PET scans. Site and shape of abnormal radioactivity accumulation were in good agreement with the tumor as demonstrated by XCT. Small tumors had a tendency to appear larger in PET than in XCT, while tumors with a mean largest diameter of more than 50.7 mm in XCT usually appeared smaller in PET. Despite considerable overlap to tumor classes with respect to their degree of tracer uptake a highly significant decreasing order of tumor-sagittal sinus ratios of radioactivity (TSR) was found, malignant gliomas ranking highest (median TSR 0.634), followed by meningiomas (median TSR 0.522) and metastases (median TSR 0.391), benign gliomas showing the least uptake (median TSR 0.307). These findings suggest that PET with (68Ga)-EDTA has a high sensitivity supplementing XCT in the diagnosis of brain tumors, and may be helpful in early detection of recurrent tumor growth after therapy.