Thallium (T1) has recently been used as a pharmaceutical for tumor imaging and staging. The aim of this study was to evaluate the clinical significance of the T1 analogue, 99m-TcMIBI (methoxyisobutylisonitrile), for imaging of intracranial
lesions.
The
advantages of MIBI were thought to be a lower radiation exposure and better image quality than with T1.
99m-Tc-MIBI SPECT studies were done in 30 patients with brain tumors (14 astrocytomas, 7 meningiomas, 2 hemangioblastomas, 2 craniopharyngiomas, 1 ependymoma, 4 metastatic tumors) and in twelve patients with non-tumorous lesions (2 abscesses, 2
granulomas, 2 cysticercosis, 3 old intracerebral hemorrages, 1 infarction, 1 postoperative gliosis, 1 unknown pathology), and semiquantitative assessment of tracer uptake was made using a ratio of radioactivity for lesion to contralateral normal
brain
(Lesion/Contralateral normal brain ; L/C).
Twenty six of thirty tumors showed high L/C ratios (>1.5) and another four tumors low L/C ratios (<1.5). Of 12 non-tumorous intracranial lesions, 11 showed little or no uptake, but one moderate uptake.
In conclusion, it appears that rain tumors show more intense focal uptake than non-tumorous brain lesion. However, further studies would be warranted to evaluate the clinical significance of MIBI SPECT in tumor staging (grading) and in
differentiating
necrosis from tumor regrowth more clearly.
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