UPTAKE OF IODINE-123-ALPHA-METHYL TYROSINE BY GLIOMAS AND NONNEOPLASTIC BRAIN-LESIONS

Using single-photon emission tomography (SPET), the radiopharmaceutica l L-3-iodine-123-alpha-methyl tyrosine (IMT) has been applied to the i maging of amino acid transport into brain tumours. It was the aim of t his study to investigate whether IMT SPET is capable of differentiatin g between high-grade gliomas, low-grade gliomas and non-neoplastic bra in lesions. To this end, IMT uptake was determined in 53 patients usin g the triple-headed SPET camera MULTISPECT 3. Twenty-eight of these su bjects suffered from high-grade gliomas (WHO grade III or IV), 12 from low-grade gliomas (WHO grade II), and 13 from non-neoplastic brain le sions, including lesions after effective therapy of a glioma (five cas es), infarctions (four cases), inflammatory lesions (three cases) and traumatic haematoma (one case). IMT uptake was significantly higher in high-grade gliomas than in low-grade gliomas and non-neoplastic lesio ns. IMT uptake by low-grade gliomas was not significantly different fr om that by non-neoplastic lesions. Diagnostic sensitivity and specific ity were 71% and 83% for differentiating high-grade from low-grade gli omas, 82% and 100% for distinguishing high-grade gliomas from non-neop lastic lesions, and 50% and 100% for discriminating low-grade gliomas from non-neoplastic lesions. Analogously to positron emission tomograp hy with radioactively labelled amino acids and fluorine-ls deoxyglucos e, IMT SPET may aid in differentiating high-grade gliomas from histolo gically benign brain tumours and non-neoplastic brain lesions; it is o f only limited value in differentiating between non-neoplastic lesions and histologically benign brain tumours.