engleski

The clinical value of brain spect with 123I- Ioflupane (DaTSCAN) in patients with movement disorders

Introduction: Parkinson’ s disease (PD) is a chronic progressive neurodegenerative central nervous system disease of unknown etiology. The basic biochemical disorder is dopaminergic nigrostriatal system hypofunction in the basal ganglia. The degree of dopaminergic neurons loss can be assessed in vivo by neuroimaging technique, with a radiopharmaceutical that selectively binds to dopamine cells which transport dopamine (dopamine transport - DAT) in the presynaptic terminal of the dopaminergic neuron in the striatum (caudate nucleus and putamen), which belong to the extrapyramidal system. Several tracers that connect to the DAT (123I-beta CIT, 123I-FP-CIT, 123I-altropane and 99mTc-TroDAT) are available, all of which are cocaine derivates, shown by single photon emission computerised tomography (SPECT), while 123I-beta CIT and 123I- FP-CIT are widely used. There is a probability that during the disease process dopa decarboxylase activity was regulated earlier, which, during the positron emission tomography (PET) with 18F- fluordopa, results in an underestimation of dopaminergic neurons loss. Therefore, tracers that connect selectively to the dopamine transporters, and for which the SPECT technique is used, are a better choice, because they give a more precise evaluation of dopaminergic neurons degeneration [1]. The progressive loss of dopaminergic neurons in the substantia nigra leads to the classic PD symptoms: bradykinesia, resting tremors, muscular rigidity and postural reflexes loss. PD is the only neurodegenerative disease for which there is an efficient symptomatic therapy, especially in the early stages of the disease. It is treated successfully by administering levodopa preparation, dopaminergic agonists, dopamine degradation blockers (MAO-B blockers and COMT- inhibitors), anticolinergics and amantadine [2]. The basic advantage of 123I-ioflupane (123I-FP- CIT) is that the stable state allowing the SPECT imaging of the brain is achieved 3 hours after the injection of the radiopharmaceutical, and DAT scintigraphy is finished on the same day. Therefore, the above-mentioned radiopharmaceutical is most widely used today [3]. It is said that the sensibility of the test for the identification of nigrostrial degeneration in PD is 97% [4]. The differential diagnosis of the idiopathic PD and other forms of degenerative parkinsonism (progressive supranuclear palsy, multiple system atrophy and Lewy body dementia) is not simple, especially at the early stage of the disease [5]. It has been noted that supranuclear palsy is characterised by profound and diffuse loss of dopaminergic neurons [1]. Aim: We have researched the clinical-diagnostic value of brain SPECT with 123I-ioflupane (DaTSCAN) in differentiating the Parkinsonian syndrome from the essential tremor for the purpose of adequate treatment. Patients and methods: Cases of PD confirmation using the DaTSCAN, as the latest diagnostic procedure performed at the Department of Nuclear Medicine and Radiation Protection of Osijek University Hospital's, are shown. DAT connecting in 17 patients with expressed and noticeable motor symptoms was studied. Patients did not take the drugs that could interfere with the dopamine transporters. The differential diagnosis of the Parkinsonian syndrome and the essential tremor was based on the visual interpretation of the allocation of the 123I-ioflupane accumulation, within caudate nucleus and putamen the large basal ganglia. The thyroid gland was blocked with 400 mg of sodium perchlorate, 60 minutes before the injection of radiopharmaceutical. SPECT (double detector gamma camera SMV Sopha DST-XLi) was performed 3 hours after intravenous injection of 185 MBq 123I-ioflupane. High-resolution collimators, 128×128 imaging matrix and a 159 KeV, 20% energy window were used. Studies were done in the period of 32 minutes, with 30 seconds per projection. Results: The demonstrations of significantly reduced accumulation of radiopharmaceuticals in the striatum correspond to the presynaptic dopaminergic deficit and are in accordance with degenerative parkinsonism diagnosis. Normal accumulation of radiopharmaceuticals in the striatum points to the regular distribution of presynaptic dopaminergic neurons found in healthy persons and in the cases of essential tremors. Those sorts of scintigrams exclude degenerative parkinsonism. The demonstration of asymmetric reduced accumulation of 123I-ioflupane in the basal ganglia, more on the one side than on the other, pointed to the advanced Parkinsonian syndrome. Conclusion: Brain SPECT with 123I-ioflupane is a reliable indicator of preservation or loss of the nigrostriatal neurons. This scintigraphic method with a radionuclide marked with dopamine transporters reliably differentiates the Parkinsonian syndrome with presynaptic dopaminergic deficit (Parkinson’ s disease, progressive supranuclear palsy and multiple system atrophy) from an essential tremor without dopaminergic deficit, and has a value in setting the precise clinical diagosis, in the reduction of the number of wrong movement disorders diagnoses and in adequate treatment of patients with Parkinsonian syndrome.

movement disorders ; Parkinson’ s disease ; DaTSCAN

Abstract of the Scientific Syposium with International Participation "40 Years of Nuclear Medicine in Osijek", November 15-17, 2007. Osijek, Croatia.