[Nuclear medicine diagnosis in diseases of the central nervous system]

Distinctive FDG-PET/CT Findings in Acute Neurological Hospital Care

A compilation of 6 distinctive ¹⁸F-fluorodeoxyglucose positron emission tomography (PET) combined with computed tomography (CT) findings in the acute setting of neurohospital care is presented. In case 1, PET/CT allowed the final diagnosis of circumscribed ischemic infarction by demonstrating a clear pattern of luxury perfusion. In case 2, diagnosis of thalamic abscess was made, whereby PET/CT demonstrated an empty zone. Hypermetabolic enlarged hilar lymph nodes and hypermetabolic spinal lumbar roots in PET/CT led to the diagnosis of neurosarcoidosis in case 3. In case 4, a hypermetabolic brain focus in PET/CT identified the seizure focus in epilepsia partialis continua. A cerebral hemispheric hypometabolism in PET/CT in case 5 supported the diagnosis of Creutzfeldt-Jakob disease, which initially mimicked acute stroke. In case 6, PET/CT detected infective endocarditis as a source of multiple cerebral ischemic lesions. In conclusion, PET/CT can contribute importantly to find the correct diagnosis in acute neurohospital patients.

Imaging with 99mTc ECDG targeted at the multifunctional glucose transport system: feasibility study with rodents

PURPOSE

To evaluate the feasibility of technetium 99m ((99m)Tc) ethylenedicysteine-deoxyglucose (ECDG) imaging in tumor-bearing rodents.

MATERIALS AND METHODS

ECDG was synthesized by means of reacting ethylenedicysteine with glucosamine, with carbodiimide as the coupling agent. Hexokinase assays were performed at an ultraviolet wavelength of 340 nm. To determine whether blood glucose level could be altered, ECDG or glucosamine was injected into six rats. In a separate study, ECDG followed by insulin was administered to three rats. To determine biodistribution, lung tumor cells were intramuscularly injected into the hind legs of 18 nude mice. The animals were then injected with (99m)Tc ECDG or fluorine 18 ((18)F) fluorodeoxyglucose (FDG) (0.037-0.074 MBq per mouse). Radioactivity was measured in tissue excised from the animals. Scintigraphy was performed in three groups: in group 1 to demonstrate that different-sized tumors could be imaged after (99m)Tc ECDG administration, in group 2 to ascertain whether tumor uptake of (99m)Tc ECDG was perfusion related, and in group 3 to demonstrate that tumor uptake of (99m)Tc ECDG occurred by means of a glucose-mediated process.

RESULTS

ECDG was positive for phosphorylation at hexokinase assay. Blood glucose level increased with ECDG injection and decreased with insulin administration. Tumor-to-brain tissue and tumor-to-muscle tissue ratios of (99m)Tc ECDG uptake were higher than those of (18)F FDG uptake. Scintigraphic results demonstrated the feasibility of (99m)Tc ECDG imaging.

CONCLUSION

There are similarities between (99m)Tc ECDG uptake and (18)F FDG uptake in tumors, and study findings supported the potential use of (99m)Tc ECDG as a functional imaging agent.