Single photon emission computer tomography of dopamine transporters in monkeys and humans with ^(99m)Tc-TRODAT-1

Background The diagnosis of Parkinson’s disease is presently based on non-specific symptoms. However, radionuclide dopamine transporters imaging can provide specific diagnostic tool for Parkinson’s disease. This study was designed to investigate the effects of imaging of dopamine transporters with 99mTc-TRODAT-1 in early diagnosis or differential diagnosis of Parkinson’s disease.Methods Nine normal monkeys were used to establish N-methyl-4-phenyl-1, 2, 3, 6-tetra-hydropyridine (MPTP) hemi-Parkinsonian animal models, and they were subjected to imaging. Twenty-nine patients with Parkinson’s disease, 12 age-matched healthy volunteers, and 18 age-matched patients with Parkinson’s syndrome were investigated. Single photon emission computer tomography (SPECT) was performed 3 hours after intravenous injection of 740 MBq 99mTc-TRODAT-1. Striatum specific uptake of 99mTc-TRODAT-1 was calculated according to the ratio of striatum (ST) to cerebellum (CB)in dopamine transporters uptake.Results In normal monkeys, bilateral ratio of ST/CB was 2.34±0.41. After the injection of MPTP, uptake rate of 99mTc-TRODAT-1 at damaged region was much lower than that at the contralateral region, resulting in a significant difference in the ratio of ST/CB (right: ST/CB=1.73±0.35; left: ST/CB=1.90±0.30), especially in hemi-Parkinsonian model monkeys (right: ST/CB=1.29±0.17; left: ST/CB=1.80±0.33). The ratios of ST/CB were 1.57±0.17 and 1.61±0.14 for the right and left respectively in the healthy volunteers, 1.04±0.29 and 1.06±0.30 in the age-matched patients with Parkinson’s disease, and 1.56±0.17 and 1.59±0.18 in the age-matched patients with Parkinson’s disease syndrome. A significant difference was noted between group of Parkinson’s disease, normal controls and Parkinson’s disease syndrome. Conclusion The results suggest that 99mTc-TRODAT-1 dopamine transporters SPECT has clinical application value in early diagnosis or differential diagnosis of Parkinson’s disease.

The role of technetium Tc99m-tetrofosmin as head and neck tumor-seeking agent:a preliminary report

Aim:To evaluate the diagnostic value of technetium Tc99m-tetrofosmin(^(99m)Tc-TF)in primary cancers of the head and neck.Methods:Single photon emission computer tomography with planar imaging of the neck for primary site evaluation and whole body scanning for assessment of metastases in 12 patients with newly diagnosed head and neck cancer.Tumor-to-background index(T/Bg)was derived in patients with positive findings(tumor or lymph nodes).Results:The tomographic images showed increased tracer uptake in pathological sites(primary tumor or lymph node)in 9 patients(overall sensitivity 75%).Primary tumor was visualised in 7 patients(sensitivity 58%)and infiltrated lymph nodes in 4 out 7 patients(sensitivity 57%).Mean values for T/Bg index were 5.44±1.28 for primary tumor and 4.25±1.67 for lymph nodes.Mean values for T/Bg index were 4.5±0.71 for patients with in situ and grade I carcinoma and 6.68±0.36 for patients with tumor grade II and III(P=0.034,Mann-Whitney U test).Conclusion:The present study demonstrates that ^(99m)Tc-TF is a valuable radiotracer for head and neck cancer imaging.To determine the potential role of this imaging protocol in clinical practice will require a larger sample size.