Imaging of recurrent brain tumors with trivalent (99m)Tc-dimercaptosuccinic acid - initial results

There is considerable chemical and structural similarity between the widely used oncophilic substance pentavalent dimercaptosuccinic acid labeled with (99m)Tc [(99m)Tc-DMSA(V)] and the renal imaging agent trivalent [(99m)Tc-DMSA(III)]. Other renal imaging agents like diethyltriamine penta acetic acid (DTPA) and glucoheptonate labeled with (99m)Tc have been used for imaging brain lesions, mainly for brain tumor imaging. The aim of this study was to evaluate technetium labeled (99m)Tc-DMSA(III) for brain tumor imaging. Single photon emission computed tomography (SPECT) of the brain with (99m)Tc-DMSA(III) was performed in twenty-three patients with brain tumors in recurrence and the results were correlated with contrast enhanced magnetic resonance imaging (MRI) findings. Ten patients had multiform blioblastoma, 7 patients had anaplastic astocystoma, 5 patients low grade glioma and 1 patient menengioma. Our results show that brain SPECT was able to detect 20 of the 21 tumors detected by the contrast enhanced MRI of the brain. The brain scan was false positive in one patient. In two other patients two sites of radiation necrosis showed no tracer concentration. We conclude that (99m)Tc-DMSA(III) concentrates in recurrent brain tumors and can be used for the imaging of these tumors.