(201)Tl-SPECT, (1)H-MRS, and MIB-1 labeling index of central neurocytomas: three case reports

BACKGROUND: The proliferative activity and metabolic features of three central neurocytomas were investigated using the findings of thallium-201 single photon emission computed tomography ((201)Tl-SPECT) and proton magnetic resonance spectroscopy ((1)H-MRS), and the MIB-1 labeling index (MIB-1 LI). METHOD: The early and delayed (201)Tl indices were calculated as the ratio of tumour to normal brain tissue uptake by (201)Tl-SPECT. In vivo single-voxel (1)H-MRS was performed with echo time of 272 msec to evaluate the metabolites including choline (Cho), N-acetyl aspartate (NAA) and creatine/phosphocreatine (Cre). An external standard reference was used to semiquantitate each metabolite. MIB-1 LI was determined in the surgical specimens. FINDINGS: The MIB-1 LI was 0.5%, 1.2%, and 7.5% in an atypical central neurocytoma without intraventricular extension. Significant (201)Tl uptake was observed on delayed images in all three central neurocytomas. (1)H-MRS showed the high Cho peaks relative to the NAA and Cre peak. The signal at 3.55 ppm, which may be due to inositol or glycine, was observed in one central neurocytoma. INTERPRETATION: Both (201)Tl-SPECT and (1)H-MRS did not reflect the proliferative potential of central neurocytomas.