Spect Radioligands

Although 123I-P-CIT is clearly useful in imaging striatal DAT, its pharmacokinetic characteristics delay imaging until the day after radioligand injection (28). It also may be somewhat less specific than desired, having a tendency to accumulate at serotonin transporters (29,30). Thus, N-Q-fluoralkyl analogs 123I-FP-P-CIT 4-iodophenyl -nortropane) and 123I-FE-P-CIT were developed. Both of these compounds bind to live and postmortem striatal DAT within 30 min and wash out of the occipital cortex...

References

Tryptophan hydroxylase activity and synaptosomal uptake of serotonin in discrete brain regions after midbrain raphe lesions correlations with serotonin levels and histochemical fluorescence. Brain Res 1972 44 165-176. 2. Samanin R, Valzelli L, Gumulka W. Inhibitory effect of midbrain raphe stimulation on cortical evoked potentials in rats. Psycho-pharmacologia 1972 24 373-379. 3. Kovacs DA, Zoll JG. Seizure inhibition by median raphe nucleus stimulation in rat....

Lysosomal Disorders

Krabbe Disorder Infants

Lysosomal disorders may present as a classic leukodystro-phy or a leukoencephalopathy associated with systemic manifestations. The disorders discussed are not exhaustive of lysosomal disease with white matter disorders and are meant to be representative. Metachromatic leukodystrophy is also known as MLD metachromatic leukoencephalopathy cerebral sclerosis, diffuse, metachromatic form sulfatide lipidosis arylsulfatase A deficiency arylsulfatase A (ARSA) deficiency and cerebro-side sulfatase...

Mitochondrial Cytopathies

Mitochondrial disorders are caused by mutations of nuclear or mitochondrial DNA encoded genes involved in oxidative phosphorylation. Mutations in these critical genes are associated with specific clinical syndromes with diverse presentations (99,100). Because mitochondria are present in many of our organs and play a key role in energy metabolism, mitochondrial encephalomyopathies often present as multisystem disorders that may manifest with neurologic, cardiac, endocrine, gastrointestinal,...

Presynaptic Da Function

18F fluorodopa FDOPA is the radioligand used mostly for quantifying the nigrostriatal dopaminergic dysfunction in PD. This tracer measures the rate of FDOPA decarboxylation and subsequent storage in the dopaminergic nerve terminals. FDOPA uptake is estimated by using a striatal occipital ratio SOR striatal occipital - 1 9,10 or influx constant K computed from dynamic data 11-13 . It has been established that FDOPA uptake is reduced in the posterior putamen but relatively preserved in the...

Summary

Positron emission tomography PET scan with 18F -6-fluoro- dihydroxyphenylalanine FDOPA is currently the imaging gold standard for diagnosing Parkinson's disease PD , but this procedure is available at only a limited number of facilities. PET cameras are expensive, they require proximity to a cyclotron, and tests are nonreimbursable. A less costly and more available test, such as a single photon emission computed tomography SPECT , may thus be helpful in the diagnosis of early or atypical PD, if...