SENSITIVITY AND SPECIFICITY OF TL-201 SINGLE-PHOTON EMISSION TOMOGRAPHY IN THE FUNCTIONAL DETECTION AND DIFFERENTIAL-DIAGNOSIS OF BRAIN-TUMORS

The aim of this retrospective study was to assess the contribution of thallium-201 single-photon emission tomography (SPET) in the detection and differential diagnosis of brain tumours. In 90 patients Tl-201 SP ET was performed because of clinical or radiological suspicion of tumo ral invasion, completed by technetium-99m hexamethylpropylene amine ox ime and Tc-99m-sestamibi SPET in some patients. For all tumours, diagn osis was based on biopsy or autopsy. Other diagnoses were made only af ter clinical and radiological follow-up for at least 6 months. Histolo gically tumours consisted of astrocytoma stage I or II (number of pati ents, n=6), astrocytoma stage III (n=8), glioblastoma multiforme (n=14 ) and oligodendroglioma (n=3), brain metastasis (n=14), lymphoma (n=3) , meningioma (n=3), pituitary adenoma (n=2), pineal tumour (n=1), coll oid cyst (n=1) and craniopharyngioma (n=1). False-negative studies inc luded pineal tumour (n=1), colloid cyst (n=1), craniopharyngioma (n=1) , astrocytomas stage I or II (n=6) and stage III (n=3), oligodendrogli oma (n=2) and metastasis in the brain stem (n=1). Additional metastase s approximately < 1.5 cm were not detected in two patients and Tl-201 SPET underestimated tumoral extent in one patient suffering from gliob lastoma multiforme (n=1). A false-positive positive study was obtained in a patient with skull metastasis (n=l). All 15 patients who were fi nally shown to suffer from ischaemic infarction had a normal SPET stud y 9-28 days after the onset of symptomatology. Of five patients with h aemorrhagic infarction, studied within 2 weeks, four were false-positi ve. Of six patients with intracranial haemorrhage, studied 9-39 days l ater, one showed focal Tl-201 accumulation. Two further false-posi