Imaging using Tc99m-tetrofosmin for the detection of the recurrence of brain tumour: a comparative study with Tc99m-glucoheptonate.

BACKGROUND In the past "blood-brain barrier" agents such as Tc99m-glucoheptonate were routinely used for the diagnosis of brain tumours. Of late, agents used for studying myocardial perfusion namely, Tc99m-tetrofosmin, Thallium-201, and Tc99m-sestamibi have replaced the "blood-brain barrier agents " when imaging is undertaken for the detection of the recurrence of brain tumours. However, the incremental diagnostic information provided by Tc99m-tetrofosmin when compared with a blood brain barrier agent in the diagnosis of recurrent brain tumour has not been evaluated till date. AIMS The study was carried out to substantiate whether Tc99m-tetrofosmin provides any incremental diagnostic information not provided by the blood brain barrier agent Tc99m-glucoheptonate. MATERIAL AND METHODS Brain SPECT scans were performed using Tc99m-tetrofosmin and Tc99m-glucoheptonate in 126 patients of recurrent brain tumour. Bio-distribution and uptake properties of both the tracers were analysed by measuring relative uptake of both the tracers in tumour compared to background (T/B ratio), nasopharynx (T/N ratio) and scalp (T/S ratio). STATISTICAL ANALYSIS Descriptive statistics were calculated for each variable. Pearson's correlation coefficient was applied to see agreement of the continuous variables. Paired t test was used to evaluate the difference between two means. RESULTS Uptake properties of both the tracers were analysed in 105 patients in whom both Tc99m-tetrofosmin and Tc99m-glucoheptonate showed concentration. The remaining 21 patients in whom the tumour mass did not show Tc99m-tetrofosmin concentration were excluded from the study. Mean T/B ratio, T/N ratio and T/S ratio was 5.83 + 2.09 and 5.99 + 2.26, 0.53 + 0.21 and 0.55 + 0.22 and 1.11 + 0.60 and 1.26 + 0.52 for Tc99m-tetrofosmin and Tc99m-glucoheptonate respectively. No statistically significant difference between T/B ratio and T/N ratio of Tc99m-tetrofosmin and Tc99m-glucoheptonate was found; p values were 0.25 and 0.83 respectively. However there was significant difference (P=0.006) between the T/S ratio of Tc99m-tetrofosmin and that of Tc99m-glucoheptonate. CONCLUSION Tc99m-tetrofosmin does not provide any incremental diagnostic information not provided by the blood brain barrier agent Tc99m-glucoheptonate.