Familial Hemiplegic Migraine: Follow-up Findings of Diffusion-Weighted Magnetic Resonance Imaging (MRI), Perfusion-MRI and [99mTc] HMPAO-SPECT in a Patient with Prolonged Hemiplegic Aura

Familial hemiplegic migraine (FHM) is a rare inherited autosomal dominant disorder. Migraine aura may last up to several weeks and then resolve without sequel. We report a 21-year-old male with FHM since the age of 3 years. Diffusion-weighted magnetic resonance imaging (DWI), perfusion-MR imaging (P-MRI) and [99mTc] hexamethyl-propyleneamine-oxime-single photon emission tomography (HMPAO-SPECT) were performed on day 2, when he was somnolent with right-sided hemiplegia, on day 9 when a mild hemiparesis was still present and on day 24 after recovery. The right central region showed normal findings in DWI, whereas P-MRI and SPECT revealed hyperperfusion on day 2, less marked on day 9, and normal findings on day 24. In conclusion, this case report indicates for the first time, by means of SPECT, P-MRI and DWI studies, that even extremely long-lasting migraine aura is not associated with cerebral ischaemia. Therefore, it supports the revised International Headache Society criteria where the term ‘persistent’ aura is proposed.

EFNS guideline on neuroimaging in acute stroke. Report of an EFNS task force

Neuroimaging techniques are necessary for the evaluation of stroke, one of the leading causes of death and neurological impairment in developed countries. The multiplicity of techniques available has increased the complexity of decision making for physicians. We performed a comprehensive review of the literature in English for the period 1965-2005 and critically assessed the relevant publications. The members of the panel reviewed and corrected an initial draft, until a consensus was reached on recommendations stratified according to the European Federation of Neurological Societies (EFNS) criteria. Non-contrast computed tomography (CT) scan is the established imaging procedure for the initial evaluation of stroke patients. However, magnetic resonance imaging (MRI) has a higher sensitivity than CT for the demonstration of infarcted or ischemic areas and depicts well acute and chronic intracerebral hemorrhage. Perfusion and diffusion MRI together with MR angiography (MRA) are very helpful for the acute evaluation of patients with ischemic stroke. MRI and MRA are the recommended techniques for screening cerebral aneurysms and for the diagnosis of cerebral venous thrombosis and arterial dissection. For the non-invasive study of extracranial vessels, MRA is less portable and more expensive than ultrasonography but it has higher sensitivity and specificity for carotid stenosis. Transcranial Doppler is very useful for monitoring arterial reperfusion after thrombolysis, for the diagnosis of intracranial stenosis and of right-to-left shunts, and for monitoring vasospasm after subarachnoid hemorrhage. Currently, single photon emission computed tomography and positron emission tomography have a more limited role in the evaluation of the acute stroke patient.

In vivo imaging of serotonin transporter occupancy by means of SPECT and [123I]ADAM in healthy subjects administered different doses of escitalopram or citalopram

BACKGROUND

Escitalopram is a dual serotonin reuptake inhibitor (SSRI) approved for the treatment of depression and anxiety disorders. It is the S-enantiomer of citalopram, and is responsible for the serotonin reuptake activity, and thus for its pharmacological effects. Previous studies pointed out that clinically efficacious doses of other SSRIs produce an occupancy of the serotonin reuptake transporter (SERT) of about 80% or more. The novel radioligand [123I]ADAM and single photon emission computer tomography (SPECT) were used to measure midbrain SERT occupancies for different doses of escitalopram and citalopram.

METHODS

Twenty-five healthy subjects received a single dose of escitalopram [5 mg (n=5), 10 mg (n=5), and 20 mg (n=5)] or citalopram [(10 mg (n=5) and 20 mg (n=5)]. Midbrain SERT binding was measured with [(123)I]ADAM and SPECT on two study days, once without study drug and once 6 h after single dose administration of the study drug. The ratio of midbrain-cerebellum/cerebellum was the outcome measure (V3") for specific binding to SERT in midbrain. Subsequently, SERT occupancy levels were calculated using the untreated baseline level for each subject. An Emax model was used to describe the relationship between S-citalopram concentrations and SERT occupancy values. Additionally, four subjects received placebo to determine test-retest variability.

RESULTS

Single doses of 5, 10, or 20 mg escitalopram led to a mean SERT occupancy of 60+/-6, 64+/-6, and 75+/-5%, respectively. SERT occupancies for subjects treated with single doses of 10 and 20 mg citalopram were 65+/-10 and 70+/-6%, respectively. A statistically significant difference was found between SERT occupancies after application of 10 and 20 mg escitalopram, but not for 10 and 20 mg citalopram. There was no statistically significant difference between the SERT occupancies of either 10 mg citalopram or 10 mg escitalopram, or between 20 mg citalopram and 20 mg escitalopram. Emax was slightly higher after administration of citalopram (84%) than escitalopram (79%). In the test-retest study, a mean SERT "occupancy" of 4% was found after administration of placebo, the intraclass correlation coefficient was 0.92, and the repeatability coefficient was 0.25.

CONCLUSION

SPECT and [123I]ADAM were used to investigate SERT occupancies after single doses of escitalopram or citalopram. The test-retest study revealed good reproducibility of SERT quantification. Similar SERT occupancies were found after administration of equal doses (in respect to mg) of escitalopram and citalopram, giving indirect evidence for a fractional blockade of SERT by the inactive R-citalopram.

Factors influencing quality of life in multiple sclerosis patients: disability, depressive mood, fatigue and sleep quality

OBJECTIVES

In a series of 504 patients with multiple sclerosis (MS), quality of life (QOL) and its main clinical and demographic determinants were assessed in comparison with healthy individuals.

MATERIALS AND METHODS

A postal questionnaire with self-completed measures of disability (Expanded Disability Status Scale, EDSS), QOL (Quality of Life Index, QLI), depressive mood (Self-rating Depression Scale, SDS), fatigue severity (Fatigue Severity Scale, FSS) and sleep quality (Pittsburgh Sleep Quality Index, PSQI) was sent to this sample of MS patients.

RESULTS

Most patients were severely disabled; almost half were mildly to severely depressed, suffering from reduced sleep quality and/or fatigue. The multiple sclerosis patients had significantly lower QLI scores than healthy controls. EDSS and SDS scores were found to be predictors of global QLI score. Regarding the different QLI domains, mean SDS scores remained predictive for all QLI items, while mean EDSS, PSQI and FSS scores were only predictive for physical domains.

CONCLUSION

Our study clearly demonstrates that depressive mood is the main factor influencing QOL. The disability status, fatigue and reduced sleep quality have an impact mainly on physical domains of life quality.

Normal striatal D2 receptor binding in idiopathic restless legs syndrome with periodic leg movements in sleep

Dopaminergic treatment is very effective in restless legs syndrome (RLS) and periodic leg movements in sleep (PLMS). However, neuroreceptor imaging studies that addressed altered striatal dopaminergic function have given controversial results. In this present study, 14 patients with idiopathic RLS (iRLS) and PLMS with a good response to dopaminergic and non-dopaminergic treatment and ten healthy sex- and age-matched controls were investigated off-medication by using 123I-IBZM and SPECT. RLS symptoms and sleep disturbances were evaluated using three nights of polysomnography, the Pittsburgh Sleep Quality Index, and the International RLS Study Group (IRLSSG) rating scale. The patients presented with sleep disturbances, a high PLMS index (56.2 +/- 33.1 per h), and severe RLS symptoms during SPECT (IRLSSG rating scale 23.1 +/- 8.0), and showed no significant differences in striatal to frontal IBZM binding to D2 receptors compared to controls (ratio striatum/frontal cortex, right side 1.60 +/- 0.10 vs 1.63 +/- 0.08, P = 0.35, NS; left side 1.61 +/- 0.11 vs 1.63 +/- 0.08, P = 0.51, NS). These findings show normal function of striatal D2 receptors in successfully treated patients with iRLS and PLMS. Dopaminergic and non-dopaminergic pretreatment does not appear to change striatal D2 receptor binding as compared to healthy controls. Structures other than striatal D2 receptors are discussed as possible causes of the treatment effects in RLS.

[PET and SPECT investigations in Alzheimer's disease]

Nuclear medicine offers a wide range of possibilities to investigate dementia. Various SPECT and PET tracers will be introduced in this article first. Different questions concerning evaluation of dementia are discussed taking Alzheimer's disease (AD) as an example. It is important to perform nuclear medicine investigations on high technical level, using standardized methods as statistical parametric mapping (SPM) for evaluation. If neuroprotective therapies are available, an early diagnosis, the determination of risk factors and longitudinal investigations will be the focus of interest and the main goal of nuclear medicine. Apart from measuring cerebral perfusion and glucose metabolism the development of new ligands, concerning the cholinergic system and the visualization of amyloid plaques, is of great importance.

Sequential MRI in a case of Creutzfeldt-Jakob disease

A 48-year-old man suddenly developed clinically and electroencephalographically nonspecific dementia. On MRI sequences, only diffusion-weighted images (DWI) of the cortex were unequivocally pathological. Obvious atrophy and basal ganglia signal changes appeared only 9 months after the onset. Brain biopsy confirmed Creutzfeldt-Jakob disease (CJD). In rapidly progressive dementia, we recommend DWI for early diagnosis of CJD.

Dopamine transporter availability in symptomatic depressed patients with seasonal affective disorder and healthy controls

BACKGROUND

During recent years hypotheses about the pathophysiology of seasonal affective disorder/winter type (SAD) have focused monoaminergic mechanisms. There is substantial evidence that serotonergic systems play an important role. The potential role of catecholaminergic pathways has not been fully explored.

METHODS

Eleven drug-free, symptomatic depressed patients with SAD and 11 healthy age- and gender-matched healthy controls were invited to participate in a 123Ibeta-CIT single photon emission computed tomography (SPECT) study to assess striatal density of dopamine transporters (DATs). The cerebellum was used as reference region. Ratios were calculated between mean counts in left and right striatum and cerebellum. These ratios minus I represent specific/non-displaceable binding and are assumed to be directly related to DAT availability at the time of binding equilibrium.

RESULTS

Displaceable 153Ibeta-CIT binding in the area corresponding to the left striatum was significantly reduced in SAD patients compared to healthy controls (10.49+/-0.91 v. 1195+/-1.54, respectively; 2-tailed P = 0.017, Mann-Whitney U test).

CONCLUSIONS

These data suggest reductions in the availability of striatal DAT binding sites in untreated symptomatic depressed SAD patients. It remains unclear whether these reductions represent a primary defect or an attempt to overcome a state of possible lowered dopamine availability in the synaptic cleft during a depressive episode of SAD. However, these findings provide evidence that brain dopaminergic systems may be involved in the pathophysiology of SAD.

In vivo (123)I IBZM SPECT imaging of striatal dopamine 2 receptor occupancy in schizophrenic patients

RATIONALE

Single photon emission computed tomography (SPECT) using (123)I iodobenzamide (IBZM) as tracer substance has been shown to be a useful tool to visualize dopamine 2 (D2) receptor occupancy.

OBJECTIVES

We investigated the striatal D2 receptor occupancy of zotepine which is referred to the class of atypical antipsychotic drugs.

METHODS

(123)I IBZM and SPECT were used to visualize striatal dopamine 2 (D2) receptor occupancy in zotepine-treated schizophrenic patients. Two groups of schizophrenic patients receiving either 150 mg/day zotepine (n=6) or 300 mg/day (n=6) underwent examination. For the quantification of striatal D2 receptor occupancy, striatal IBZM binding in patients treated with antipsychotics was compared to untreated healthy controls (n=8) reported earlier.

RESULTS

Zotepine led to a mean overall striatal D2 receptor occupancy of 73%. Patients with 150 mg daily showed a significantly lower occupancy (65.8%, SD=6.2) than patients with 300 mg/day (77.8%, SD=10.7; P<0.05). No clinically relevant extrapyramidal side effects occurred during treatment with zotepine.

CONCLUSIONS

There was no correlation between the degree of striatal D2 receptor occupancy and clinical improvement.

Nuclear medicine in the preoperative evaluation of epilepsy

The clinical usefulness of nuclear medicine in the preoperative evaluation of epilepsy is highlighted with regard to non-lesional temporal lobe epilepsy, extratemporal epilepsy, bitemporal interictal epileptiform discharges (IEDs) and in dual pathology and cortical dysgenesis. Ictal single photon emission computed tomography (SPECT) shows good sensitivities in the correct lateralization of an electroencephalogram-defined epileptic focus in lesional and, to a lesser extent, non-lesional epilepsy. Positron emission tomography (PET) using 18F-fluorodeoxyglucose or 11C-flumazenil gives a good detection rate of the seizure onset zone in non-lesional cases and extratemporal epilepsy. The investigation of patients with bitemporal IEDs can confirm the existence of bitemporal seizure onset. For patients with a dual pathology or cortical dysgenesis nuclear medicine offers the opportunity to delineate the existence or extension of abnormalities possibly responsible for the seizure disorder.

No evidence for in vivo regulation of midbrain serotonin transporter availability by serotonin transporter promoter gene polymorphism

BACKGROUND

A polymorphism in the serotonin transporter promoter gene region (5-HTTLPR) has been shown to influence the quantity of serotonin transporter expressed in human cell lines: the 5-HTTLPR short allele (s) has been associated with reduced 5-HTT expression when compared to cells carrying the 5-HTTLPR long allele (l). We performed a single photon emission computed tomography (SPECT) study using the ligand [(123)I]-2-beta-carbomethoxy-3-beta-(4-iodophenyl)tropane ([(123)I]-beta-CIT) to measure 5-HTT availability in 16 healthy subjects genotyped for 5-HTTLPR.

METHODS

SPECT scans were performed 24 hours after tracer injection, regions of interest anatomically corresponding to the thalamus-hypothalamus and mesencephalon-pons areas were compared to the binding in the cerebellum, representing the nondisplaceable [(123)I]-beta-CIT-binding (results expressed as target activity minus cerebellum activity/cerebellum activity). DNA from peripheral nuclear blood cells was genotyped for 5-HTTLPR using standard polymerase chain reaction methods.

RESULTS

Specific binding ratios in the thalamus-hypothalamus were 2.65 +/- 0.4 in subjects with the l/l genotype (n = 3), 2.76 +/- 0.5 in subjects with the l/s genotype (n = 9), and 2.77 +/- 0.4 in subjects with the s/s genotype (n = 4). Binding ratios in the mesencephalon-pons were 1.43 +/- 0.3 (l/l; n = 3), 1.37 +/- 0.3 (l/s; n = 9), and 1.28 +/- 0.3 (s/s; n = 4). None of these differences was statistically significant.

CONCLUSIONS

Our data provide no evidence for in vivo functional regulation of 5-HTT availability by 5-HTTLPR in the thalamus-hypothalamus and mesencephalon-pons of healthy subjects.

A medial to lateral shift in pre-movement cortical activity in hemi-Parkinson's disease

OBJECTIVE

Recent evidence suggests that cortical activity associated with voluntary movement is relatively shifted from medial to lateral premotor areas in Parkinson's disease. This shift occurs bilaterally even for unilateral responses. It is not clear whether the shift in processing reflects an overall change in movement strategy, thereby involving alternate cortical areas, or reflects a compensatory change whereby, given the appropriate conditions, less impaired cortical areas are able to provide a similar function in compensation for those areas which are more impaired. This issue was examined in patients with hemi-Parkinson's disease, in whom basal ganglia impairment is most pronounced in one hemisphere.

METHODS

Fourteen patients with hemi-Parkinson's disease and 15 age-matched control subjects performed a Go/NoGo finger movement task and the contingent negative variation (CNV) was recorded from 21 scalp positions.

RESULTS AND CONCLUSIONS

Maximal CNV amplitudes were found over central medial regions for control subjects, but were shifted more frontally for Parkinson's disease patients, reduced in amplitude over the midline and lateralized towards the side ipsilateral to the greatest basal ganglia impairment. This shift in cortical activity from medial to lateral areas in Parkinson's disease patients appears to reflect a compensatory mechanism operating predominantly on the side of greatest basal ganglia impairment.

[123I] beta-CIT and single photon emission computed tomography reveal reduced brain serotonin transporter availability in bulimia nervosa

BACKGROUND

Impaired serotonin transmission has been implicated in the pathophysiology of eating disorders. We investigated the in vivo availability of brain serotonin transporters and dopamine transporters in bulimia nervosa patients.

METHODS

Approximately 24 hours after injection of [123I]-2beta-carbomethoxy-3beta-(4-iodophenyl)tropane ([123I] beta-CIT), single photon emission computed tomography scans were performed in 10 medication-free, female bulimic patients and 10 age-matched, healthy females. For quantification of brain serotonin transporter and dopamine transporter availability, a ratio of specific to nonspecific [123I] beta-CIT brain binding was used (V(3)" = target region - cerebellum/cerebellum).

RESULTS

Drug-free bulimia nervosa patients showed a 17% reduced brain serotonin transporter availability in the hypothalamus and thalamus, as compared with healthy control subjects (2.4 +/- 0.4 vs. 2.9 +/- 0.4, p =.026), and a similar reduction in striatal dopamine transporter availability. There was a negative correlation of illness duration and serotonin transporter availability (r = -.65; p =.042) and a strong positive correlation between hypothalamic/thalamic and striatal V(3)" (r =.80, p <.001).

CONCLUSIONS

This first report of reduced [123I] beta-CIT binding in a relatively small group of patients with bulimia nervosa suggests a reduced hypothalamic and thalamic serotonin transporter availability in bulimia, which is more pronounced with longer duration of illness.

No change in striatal dopamine re-uptake site density in psychotropic drug naive and in currently treated Tourette's disorder patients: a [(123)I]-beta-CIT SPECt-study

BACKGROUND

There is evidence that Tourette's disorder (TD) is associated with abnormalities in the dopaminergic system involving the dopamine transporter (DAT). Data from [(123)I]-beta-CIT single photon emission computed tomography (SPECT) studies and postmortem findings concerning DAT densities in TD patients are not conclusive. The objective of our study was to measure DAT densities with [(123)I]-beta-CIT binding in TD patients who were either psychotropic drug naive or currently treated with antipsychotics (AP) and healthy controls.

METHOD

Altogether 20 TD patients were investigated. A total of 15 patients were psychotropic drug naive and five were currently treated with AP. Ten psychotropic drug naive patients were compared with ten age and sex matched healthy subjects. Five currently treated patients were compared with five age and sex matched psychotropic drug naive TD patients. The investigation was carried out using [(123)I]-beta-CIT (2-beta-carbomethoxy-3-beta(4-iodophenyl)-tropane and SPECT. Regions of interest (ROI) were drawn over the striatum and the cerebellum.

RESULTS

The DAT densities measured by the striatal/cerebellar (S/C) binding ratio did not differ between drug naive TD patients and the controls. The difference between currently AP treated and psychotropic drug naive TD patients did not reach the level of significance. There was no correlation between the ratio and severity of tics and illness.

CONCLUSION

Our study with psychotropic drug naive TD patients contributed to clarify the inconsistent results concerning the DAT.

Hypertrophic chronic pachymeningitis as a localized immune process in the craniocervical region

Hypertrophic chronic pachymeningitis (HCP) is a rare disorder that causes intracranial or spinal thickening of the dura mater. This report describes a patient with progressive HCP in the craniocervical region associated with signs of rheumatic disease. A ventricular-atrial shunt had to be inserted because of increased intracranial pressure. The patient improved after suboccipital craniotomy, C1 to C6 laminectomy, and removal of the thickened dura. Additional therapy with methotrexate stopped progression, which was documented by MRI and PET.

[123I]beta-CIT SPECT in multiple system atrophy, progressive supranuclear palsy, and corticobasal degeneration

Differentiation between Parkinson's disease (PD) and other neurodegenerative disorders with parkinsonian features, such as multiple system atrophy (MSA), progressive supranuclear palsy (PSP), and corticobasal degeneration (CBD), is difficult on clinical grounds. We studied the pattern of dopaminergic degeneration in 18 patients with probable MSA, 8 patients with PSP, 4 patients with CBD, 48 patients with PD and a similar degree of disability, and 14 control subjects performing single photon emission computed tomography (SPECT) 20 hours after injection of [123I]beta-CIT. Overall striatal binding was significantly reduced in MSA (-51% of normal mean), PSP (-60%), CBD (-35%), and PD (-58%), without overlap with control values. Asymmetry of striatal beta-CIT binding was significantly increased in patients with CBD and PD, as compared with control subjects. Although asymmetry seemed to be less pronounced in MSA and PSP than in PD, this was not statistically significant. Putamen-caudate nucleus ratios in patients with PD, MSA, and PSP, but not with CBD, were significantly reduced, as compared with control subjects. In conclusion, [123I]beta-CIT SPECT reliably enables the visualization of the presynaptic dopaminergic lesion in patients with MSA, PSP, and CBD. In most patients, however, it does not seem to be possible to differentiate these disorders from PD with this method.

SPECT and PET imaging of the dopaminergic system in Parkinson's disease

This paper gives an overview of the clinical importance of SPECT and PET imaging of the dopaminergic system in the differential diagnosis and for the determination of the progression rate of Parkinson's disease (PD). D2 receptor imaging can help to differentiate multiple system atrophy (MSA) and progressive supranuclear palsy (PSP) from PD. In patients treated with neuroleptics it is possible to determine the rate of striatal D2 receptor blockade using this technique. This occupancy rate parallels the occurrence of parkinsonian side effects. Its measurement helps in the selection of newer atypical neuroleptics, which can be used to treat drug-induced psychosis in PD because they do not aggravate parkinsonian symptoms. Imaging of dopaminergic neurons with [123I]beta-CIT SPECT or [18F]DOPA PET is a way to visualize and quantify the nigrostriatal dopaminergic lesion in PD. Findings correlate with clinical rating scales and demonstrate the feasibility of detecting the preclinical lesion in patients with hemiparkinson or familial PD. [123I]beta-CIT SPECT can easily distinguish patients with essential tremor and patients with "lower body parkinsonism" due to a subcortical vascular encephalopathy. MSA and PSP cannot be separated from PD with this method alone. Longitudinal studies with [123I]beta-CIT SPECT and [18F]DOPA PET can quantify the progression rate in PD. SPECT results from our own group show a low rate of progression in patients with a long duration of disease and a more marked progression rate in patients with shorter disease duration. In the former group regions in the striatum with higher beta-CIT binding at the time of the first SPECT scan decline faster than regions with lower binding. These findings suggest a curvilinear course of progression which starts at different time points in different striatal regions and which levels off after several years of disease duration. These findings are in line with data from PET studies and underline the importance of an early start of neuroprotective strategies. Preliminary data from PET and SPECT studies in early PD suggest that dopamine agonists might have a slight neuroprotective effect and might slow down the rate of progression of the disease.

Excessive daytime sleepiness in patients suffering from different levels of obstructive sleep apnoea syndrome

Excessive daytime sleepiness (EDS) is a frequent symptom of patients with obstructive sleep apnoea (OSA). EDS is a high-risk factor for accidents at work and on the road. Thirty untreated patients with different levels of severity of OSA were studied concerning night sleep and EDS. The criterion for severity was the respiratory disturbance index (RDI): 15 patients were classified as 'moderately' apnoeic (RDI < 40), 15 as 'severely' apnoeic (RDI > 40). Following night-time polysomnography, objective and subjective aspects of EDS were studied. To assess objective EDS the Maintenance of Wakefulness Test (MWT) and a computer-based vigilance performance test were used. Subjective EDS was determined using the Stanford Sleepiness Scale (SSS), the Epworth Sleepiness Scale (ESS) and the Visual Analogue Scales for Performance (VAS-P) and Tiredness (VAS-T). Well-being was assessed using the Scale of Well-Being by von Zerssen (Bf-S/Bf-S'). Severe apnoea patients spent more time in stage 1 and less in slow-wave sleep. MWT latencies tended to be shorter in the severe apnoea group. Vigilance testing revealed no group differences. Patients with moderate apnoea described themselves as more impaired in all subjective scales, but only SSS scores reached statistical significance. Our results suggest that there is no simple correlation between polysomnographic and respiratory sleep variables at night on the one hand, and the extent of EDS on the other hand. Furthermore, subjective and objective evaluation of EDS does not yield the same results. New approaches which allow a more detailed analysis of night sleep and daytime function are required to identify high-risked patients.

[123I]-beta-CIT SPECT imaging shows reduced brain serotonin transporter availability in drug-free depressed patients with seasonal affective disorder

BACKGROUND

Numerous findings indicate alterations in brain serotonin systems in seasonal affective disorder (SAD). [(123)I]-2-beta-carbomethoxy-3-beta-(4-iodophenyl)-tropane ([(123)I]-beta-CIT) labels serotonin transporters (5-HTTs) in the midbrain. We performed a [(123)I]-beta-CIT single photon emission computer tomography (SPECT) study under the hypothesis of lower [(123)I]-beta-CIT binding reflecting reduced central 5-HTT availability in depressed SAD patients.

METHODS

Depressed SAD patients and healthy control subjects were investigated using [(123)I]-beta-CIT SPECT 4 hours and again 24 hours after tracer injection. Subjects had either never used psychotropic medication or had been drug-free for at least 6 months prior to the investigation. Specific-to-nondisplaceable partition coefficient (V(3)") was calculated for the thalamus-hypothalamus and the midbrain-pons; the cerebellum served as a reference region.

RESULTS

Patients showed a reduction in V(3)" in thalamus-hypothalamus (2.41+/-0.3 vs. 2.84+/-0.4; p = .026) 24 hours post tracer injection (p.i.). No difference between patients and control subjects was found in midbrain-pons (1.31+/-0.2 vs. 1.42+/-0.2; p = .39). No differences were detected in the SPECT acquisitions 4 hours p.i.

CONCLUSIONS

Depressed SAD patients showed lower specific-to-nondisplaceable [(123)I]-beta-CIT binding in the region of interest (ROI) thalamus-hypothalamus. The small size of the midbrain-pons ROI may have contributed to the failure to show a difference in this ROI as well. Similar to reduced midbrain 5-HTT availability in nonseasonal depression, depression in SAD seems to be associated with reduced 5-HTT availability to the thalamus-hypothalamus.

Seasonal variation of availability of serotonin transporter binding sites in healthy female subjects as measured by [123I]-2 beta-carbomethoxy-3 beta-(4-iodophenyl)tropane and single photon emission computed tomography

BACKGROUND

Previous studies have indicated annual variations in central and peripheral serotonergic activity. In the present study we studied five women in summer and six women in winter and evaluated possible differences in availability of brain serotonin transporters between summer and winter.

METHODS

We employed the single photon emission computed tomography ligand [123I]-2 beta-carbomethoxy-3 beta-(4-iodophenyl)tropane ([123I] beta-CIT) to visualize binding to the serotonin transporter site in the human thalamus/hypothalamus midbrain area in vivo. Brain imaging studies were performed in one group between May and August and in the other between November and December.

RESULTS

We found significant differences in displaceable [123I] beta-CIT binding in the region corresponding to thalamus/hypothalamus between the summer group and the winter group (1.9 +/- 0.3 vs. 1.4 +/- 0.2, respectively; p < .01).

CONCLUSIONS

The results of the present study suggest reduced brain serotonin transporter availability in winter. This finding further substantiates evidence of seasonal variations in brain serotonergic function.

Imaging serotonin and dopamine transporters with 123I-beta-CIT SPECT: binding kinetics and effects of normal aging

[123I]beta-carbomethoxy-3-beta-(4-iodophenyl)-tropane (CIT) is a useful ligand for dopamine transporters (DATs) and serotonin transporters (5-HTTs). Previous SPECT studies have shown a state of sustained equilibrium in the striatum on day 2 after injection that allows quantification of striatal DATs using a simple ratio of specific-to-nondisplaceable binding. The aim of this study was to investigate the kinetics of [123I]beta-CIT uptake in the thalamus, hypothalamus, and midbrain, areas known to contain 5-HTTs in high densities.

METHODS

SPECT with a triple-head camera was performed on 16 healthy volunteers (13 women, 3 men; mean age [+/-SD], 32 +/- 11 y) after intravenous bolus injection of 130 +/- 20 MBq (3.5 +/- 0.5 mCi) [123I]beta-CIT. Two individuals were scanned 1, 2, 4, 7, 10, 13, 16, and 24 h after injection, and the remaining 14 were scanned 4, 7, 10, 20, and 24 h after injection. Values from 19 previously examined healthy volunteers (8 women, 11 men; mean age, 52 +/- 20 y) were included in the analysis to study the age dependency of beta-CIT binding in striatal and 5-HTT-rich brain areas in a larger control sample.

RESULTS

Peak uptake 4 h after injection, followed by stable uptake until 10 h and a slow decrease until 24 h, was observed in the thalamus-hypothalamus region. Activity in the midbrain-pons region peaked 2 h after injection. Because of a concomitant slow but steady decline of uptake in reference regions starting 4 h after injection, a higher stability of binding ratios for 5-HTT-rich brain areas was observed on day 2, suggesting that a state of transient equilibrium is reached between 20 and 24 h but that conditions are only close to transient equilibrium between 4 and 10 h after injection for 5-HTT-rich brain areas. In addition to an age-related decline of striatal [123I]beta-CIT binding of 6.6% per decade, a significant age-associated decrease of beta-CIT binding of 3-4% per decade was found in 5-HTT-rich brain areas. The decline of beta-CIT binding in these regions may be explained, at least in part, by a loss of monoamine transporters with age but may also be related to age-associated morphologic changes.

CONCLUSION

[123I]beta-CIT appears to be a suitable ligand for imaging serotonin transporters with SPECT. However, careful age matching is warranted for [123I]beta-CIT SPECT studies of 5-HTT changes in patients with neuropsychiatric disorders.

Regional cerebral blood flow during temporal lobe seizures associated with ictal vomiting: an ictal SPECT study in two patients

PURPOSE

Ictal vomiting represents a rare clinical manifestation during seizures originating from the temporal lobes of the nondominant hemisphere. The precise anatomic structures responsible for generation of ictal vomiting remain to be clarified. Ictal single photon emission computed tomography (SPECT), which allows one to visualize the three-dimensional dynamic changes of regional cerebral blood flow (rCBF) associated with the ongoing epileptic activity, should be useful to study the brain areas activated during ictal vomiting.

METHODS

We performed ictal Tc-HMPAO SPECT scans in two patients with mesial temporal lobe epilepsy (MTLE) whose seizures were characterized by ictal retching and vomiting. MTLE was documented by typical clinical seizure semiology, interictal and ictal EEG findings, hippocampal atrophy on magnetic resonance imaging (MRI) scan, and a seizure-free outcome after selective amydalohippocampectomy. In both patients, seizures originated in the nondominant temporal lobe. We obtained accurate anatomic reference of rCBF changes visible on SPECT by a special coregistration technique of MRI and SPECT. We used ictal SPECT studies in 10 patients with MTLE who had seizures without ictal vomiting as controls.

RESULTS

In the two patients with ictal vomiting, we found a significant hyperperfusion of the nondominant temporal lobe (inferior, medial, and lateral superior) and of the occipital region on ictal SPECT. In patients without ictal vomiting, on the contrary, these brain regions never were hyperperfused simultaneously.

CONCLUSIONS

Ictal SPECT provides further evidence that activation of a complex cortical network, including the medial and lateral superior aspects of the temporal lobe, and maybe the occipital lobes, is responsible for the generation of ictal vomiting.

Application of correlation dimension and pointwise dimension for non-linear topographical analysis of focal onset seizures

For many patients who are candidates for epilepsy surgery, non-invasive evaluation fails to provide sufficient information to permit surgical treatment. Since there are also definite risks and considerable costs associated with invasive procedures, new (non-invasive) techniques are required. This study provides empirical evidence that a non-linear approach applied to ictal surface electroencephalograms (EEGs) can help to delineate the area of seizure onset and may prove useful in complementing visual analysis of the EEG. Multichannel EEGs, recorded from eight patients with different drug-resistant localisation-related epilepsies, were analysed using the concept of correlation dimension and two extensions based on the pointwise dimension. The latter also provided results in cases where assessment of the correlation dimension was not feasible. Comparative values between 2 and 6 were accepted as the result of the algorithms, mostly 3-4 for the EEG channels strongly reflecting epileptic activity, and 4-6 for the other signals. The proportion of accepted pointwise values was usually 200-800% for strong epileptic EEG activity compared to the other data. The approach permitted the characterisation of the scalp area reflecting epileptic activity. The results obtained were in perfect concordance with those obtained during pre-surgical work-up and confirmed by the post-operative outcome.

[123I]beta-CIT and SPECT in essential tremor and Parkinson's disease

Resting and postural tremor may occur in essential tremor (ET) and Parkinson's disease (PD). The aim of the present study was to investigate the cocaine derivative [123I]beta-CIT, which labels striatal dopamine transporters, and SPECT in differentiating these diseases.

METHODS

30 healthy volunteers, 32 patients with ET and 29 patients with idiopathic PD of Hoehn/Yahr stage I were investigated. Specific over nondisplaceable binding ratios (target/cerebellum-1) were calculated for the striatum, the caudate nucleus and the putamen separately as well as a ratio putamen/caudate and the percent deviation of each patient's ratio from age-expected control values.

RESULTS

Striatal [123I]beta-CIT binding ratios in ET were within normal ranges and showed only a discrete elevation to age-expected control values (+14.6%). In PD significantly reduced specific binding was evident not only contralaterally to the clinically affected side (putamen: -62%, caudate nucleus: -35%), but also ipsilaterally (putamen: -45%, caudate nucleus: -22%). All investigated parameters differed significantly between PD and controls and ET respectively.

CONCLUSION

Imaging striatal dopamine transporters with [123I]beta-CIT and SPECT could clearly distinguish between ET and PD in an early stage of the disease. Findings do not suggest a subclinical involvement of dopaminergic nigrostriatal neurons in ET.

In vivo 123I IBZM SPECT imaging of striatal dopamine-2 receptor occupancy in schizophrenic patients treated with olanzapine in comparison to clozapine and haloperidol

We investigated the degree of striatal dopamine-2 (D2) receptor occupancy in six schizophrenic patients receiving clinically effective antipsychotic treatment with olanzapine 10-25 mg/day in comparison to patients treated with clozapine 300-600 mg/day (n = 6) or haloperidol 5-20 mg/day (n = 10). 123I Iodobenzamide (IBZM) and single photon emission computerized tomography (SPECT) were used for the visualization of striatal D2 receptors. For the quantification of striatal D2 receptor occupancy, striatal IBZM binding in patients treated with antipsychotics was compared to that in untreated healthy controls (n = 8) reported earlier. Olanzapine led to a mean striatal D2 receptor occupancy rate of 75% (range 63-85). Haloperidol-treated patients showed dose-dependently (Pearson r = 0.64; P < 0.05) a significantly higher (P < 0.05) mean occupancy rate of 84% (range 67-94). During clozapine treatment, the mean D2 receptor occupancy of 33% (range < 20-49) was significantly lower than with olanzapine (P < 0.005). The higher striatal D2 receptor occupancy of haloperidol was correlated with the incidence and severity of extrapyramidal motor side-effects (EPS). No clinical relevant EPS occurred during treatment with olanzapine or clozapine. There was no correlation between the degree of striatal D2 receptor occupancy and clinical improvement.

In vivo visualization of serotonin transporters in the human brain during fluoxetine treatment

Beta-CIT can be used as a tracer for SPECT to visualize serotonin transporters in the human brain. We present a case of bulimia nervosa and major depressive disorder, who had been treated with up to 60 mg/d fluoxetine for several weeks. Four hours after injection of the tracer more than 40% of serotonin transporters were blocked. To our knowledge, this is the first direct documentation of the pharmacodynamic action of fluoxetine in the human brain in vivo.

Monitoring of median nerve somatosensory evoked potentials in carotid surgery

The purpose of this study was to compare median somatosensory evoked potentials (SEP) in patients undergoing carotid endarterectomy (CEA) with routine shunting and nonshunting (excluding the option of selective shunting) and to evaluate the significance of a decrease in the amplitude of the cortically generated waveforms of the SEP and/or an increase in the central conduction time (CCT) on the one hand, and that of a loss of the cortical SEP, on the other. Somatosensory evoked potentials were recorded in 32 patients before, during, and after CEA with routine shunting or nonshunting. The N13 and N20 latency, the CCT, and the N20/P25 amplitude were evaluated. In addition, a meta-analysis of 15 previous studies was performed comprising a total of 3,136 patients. The intraoperative cortical SEP showed no differences between shunted and nonshunted patients, apart from the preclamping value of the N20/P25 amplitude which was lower in the nonshunted subjects. The number of patients with decreased and/or delayed cortical SEP (findings frequently used as criterion for selective shunting) was similar in the two study groups. A loss of the cortical SEP occurred in one patient operated on without an indwelling shunt. None of these patients had a new neurologic deficit after surgery. In the meta-analysis, the positive predictive value of decreased and/or delayed cortical SEP was extremely poor, that of absent cortical SEP was poor to moderate and the prevalence of new neurologic deficits was similar in patients undergoing CEA with routine shunting-nonshunting and those with selective shunting-nonshunting. Our study suggests that decreased and/or delayed cortical SEP are unreliable predictors of the neurological outcome of CEA patients and consequently an unsuitable criterion for selective shunting. The meta-analysis confirms this finding and shows that the neurologic outcome is not improved by using an indwelling shunt selectively based on SEP monitoring.

Sertindole and dopamine D2 receptor occupancy in comparison to risperidone, clozapine and haloperidol - a 123I-IBZM SPECT study

The striatal D2 dopamine binding was studied in schizophrenic patients treated with the novel atypical antipsychotic drug sertindole (n=10). Comparisons were obtained with haloperidol (n=8), clozapine (n=6), risperidone (n=11) and untreated healthy controls (n=8) of a dataset which has partly been reported previously. 123I-Iodobenzamide (IBZM) single photon emission computerized tomography (SPECT) was used for estimation of striatal dopamine D2 receptor binding. Sertindole-treated patients exhibited significantly (P < 0.001) lower levels of striatal D2 binding (BG/FC ratio:1.28) compared with those treated with haloperidol (BG/FC ratio:1.09) and risperidone (8 mg:1.18) but significantly (P < 0.005) higher levels compared with clozapine (BG/FC ratio: 1.49). However, if patients were pretreated with a depot neuroleptic, significantly (P < 0.05) higher striatal D2 binding (BG/FC ratio:1.12) has been obtained. Since sertindole has been shown to exert distinct clinical efficacy for treatment of positive and negative symptoms, our data are indicative that antipsychotic efficacy is not associated with a high degree of striatal D2 receptor occupancy in schizophrenic patients.

Imaging of cerebral blood flow with technetium-99m-HMPAO and technetium-99m-ECD: a comparison

Because 99mTc-HMPAO and 99mTc-ECD are both used for SPECT imaging of cerebral blood flow, the question arises whether there are any differences in their respective regional cerebral distribution. For that purpose, visual and semiquantitative comparisons between 99mTc-HMPAO and 99mTc-ECD studies were performed.

METHODS

Seventeen patients (4 women; 13 men; age 45-89 yr; mean age 71 yr) with various neurological diseases, except acute/subacute stroke, were investigated twice with 99mTc-HMPAO and 99mTc-ECD using a triple-headed rotating SPECT camera. After image reorientation, the two studies were evaluated visually. Seventy regions of interest (ROIs) were drawn manually and the same set of ROIs was applied in both studies. Regional indices (RI) normalized to individual brain values were calculated and first compared between two random patient groups. Second, for all patients, RI for 70 and later for 27 regions (gained after summing values of corresponding regions in different brain slices) were compared by using a paired Student's t-test applying Bonferroni's correction.

RESULTS

Visual evaluation demonstrated relatively high 99mTc-ECD uptake in occipital and comparatively low uptake in mediotemporal regions. Calculation of RI revealed significantly higher values in the right cerebellum, brainstem, mediotemporal regions, right basal ganglia and the thalamus in the 99mTc-HMPAO SPECT studies and higher values in the occipital, supratemporal/inferior parietal and parietal cortex in the 99mTc-ECD SPECT studies, respectively.

CONCLUSION

Significant differences in regional tracer distribution between 99mTc-HMPAO and 99mTc-ECD could be detected, probably caused by different tracer kinetics. The results indicate that direct comparisons of studies performed with 99mTc-HMPAO and 99mTc-ECD are not possible and the use of either tracer can be favorable in different clinical questions.

[Sleep disorders in neurology. Hypersomnia]

Hypersomnia (excessive sleepiness) accompanies many diseases. 14% of the total Austrian population regularly have problems staying awake during the day or are prone to taking spontaneous naps. Hypersomnia is a symptom of the sleep apnea syndrome, which is a risk factor for cerebrovascular disorders. Daytime sleepiness is also a characteristic symptom of narcolepsy, idiopathic hypersomnia, episodic hypersomnia, and many more neurological or psychiatric disorders; it can also be drug induced. Involvement of brain structures which are essential for the regulation of the sleep wake cycle as a result of neurological disorders can likewise lead to hypersomnia. Symptomatic treatment is necessary when treatment of the causal factors is not possible or no improvement has been achieved.

Iodine-123-epidepride-SPECT: studies in Parkinson's disease, multiple system atrophy and Huntington's disease

Epidepride is a benzamide derivative with very high affinity for D2 receptors, which, in its [123I]-labeled form, can be used for SPECT. The aim of this study was to evaluate the usefulness and accuracy of [123I]epidepride-SPECT for the differential diagnosis of movement disorders.

METHODS

SPECT imaging with a triple-headed scintillation camera was performed in 9 patients with Parkinson's disease, 9 patients with probable multiple system atrophy (MSA), 1 patient with progressive supranuclear palsy, 16 patients with Huntington's disease (HD) and 14 controls, 3 hr after the intravenous injection of 3.7 +/- 1.3 mCi of [123I]epidepride. The striatum-to-cerebellum ratio - 1, reflecting the specific-to-nondisplaceable binding ratio, was used as a semiquantitative measure of D2 receptor binding.

RESULTS

Kinetic studies showed peak striatal uptake about 3 hr postinjection and a slow decline thereafter. The striatum-to-cerebellum ratio - 1 was significantly reduced in MSA (11.8 +/- 3.9, compared to controls, 19.0 +/- 6.3; p < 0.01) and in patients with HD (8.8 +/- 3.2; p < 0.00005) but normal in Parkinson's disease (15.8 +/- 3.6; not significant). A high interindividual variation of specific striatal epidepride binding (striatum - cerebellum; cpm/mCi x kg) was found in controls and in all patient groups. The interindividual variation of striatum-to-cerebellum ratios was lower but still considerable. In half of the MSA patients, the specific-to-nondisplaceable binding ratio fell within the range of controls. The use of various cortical reference regions did not improve discrimination between MSA and controls or Parkinson's disease patients, respectively. The discrimination of HD patients from controls was better, with overlap in only two cases. In one HD patient, calculation of the striatum-to-cerebellum ratio was almost impossible due to extremely low nonspecific binding. Possible explanations for the large variation of the ratios, resulting in an overlap between controls and different patient groups, are very low counting rates in the reference region and the fact that a transient binding equilibrium may not be achieved after bolus injection of epidepride.

CONCLUSION

Epidepride appears to be a useful SPECT ligand for studying dopamine D2 receptors. However, its markedly higher specific-to-nondisplaceable binding ratio in comparison to those of iodobenzamide or other D2 ligands did not result in a better discrimination between different basal ganglia disorders. The calculation of plasma input curves and volumes of distribution might improve the accuracy of [123I]epidepride-SPECT.

IBZM SPECT imaging of striatal dopamine-2 receptors in psychotic patients treated with the novel antipsychotic substance quetiapine in comparison to clozapine and haloperidol

We investigated the striatal dopamine-2 (D2) receptor occupancy caused by different antipsychotic substances in 18 psychotic patients (16 with schizophrenic and two with schizoaffective disorder according to DSM-IV) with single photon emission computed tomography (SPECT) using 123I-iodobenzamide (IBZM) as tracer substance. Four patients were treated with the novel antipsychotic compound quetiapine (300-700 mg/day), six with clozapine (300-600 mg/ day) and eight with haloperidol (10-20 mg/day). They were compared with eight healthy controls. Measurement of S/F ratios and consecutive calculation of D2 receptor occupancy revealed a significantly lower striatal D2 occupancy rate with quetiapine and clozapine in comparison to haloperidol. In correspondence with the low striatal D2 receptor occupancy rates and again in contrast to the haloperidol treatment group, there were no extrapyramidal motor side-effects (EPS) in the quetiapine and clozapine treatment groups. Therefore, the reported data support the position that quetiapine can be considered to be an atypical antipsychotic substance due to its relatively weak striatal D2 receptor blocking property and therefore its low propensity to induce EPS.

Previous treatment as a confounding variable in studies with novel antipsychotics: two cases of high dopamine-2 receptor occupancy with quetiapine

Previous treatment can be a confounding variable in studies with novel antipsychotics. Quetiapine is a new antipsychotic substance with a low affinity for dopamine-2 (D2) receptors. Preliminary SPECT and PET investigations revealed only a low striatal D2 receptor occupancy rate. However, we present two cases of high striatal D2 receptor occupancy (51% and 71%) measured with 123I IBZM SPECT during quetiapine monotherapy. Both patients had previously received continuous treatment with typical neuroleptics. We present evidence that the previous antipsychotic therapy influenced D2 receptor binding of 123I IBZM during quetiapine treatment weeks after cessation of typical neuroleptics. This might be of importance for the design of clinical trials and brain imaging studies in the future.

Topographic distribution of sleep spindles in young healthy subjects

The application of an automatic sleep spindle detection procedure allowed the documentation of the topographic distribution of spindle characteristics, such as number, amplitude, frequency and duration, as a function of sleep depth and of recording time. Multichannel all-night EEG recordings were performed in 10 normal healthy subjects aged 20-35 years. Although the interindividual variability in the number of sleep spindles was very high (2.7 +/- 2.1 spindles per minute stage 2 sleep), all but two subjects showed maximal spindle activity in centro-parietal midline leads. Moreover, this topography was seen in all sleep stages and changed only slightly--to a more central distribution--towards the end of the night. On the other hand, slow (11.5-14 Hz) and fast (14-16 Hz) spindles showed a completely different topography, with slow spindles distributed anteriorly and fast spindles centro-parietally. The number of sleep spindles per min was significant depending on sleep stages, with the expected highest occurrence in stage 2, and on recording time, with a decrease in spindle density from the beginning towards the end of the night. However, spindle amplitude, frequency and individual duration was not influenced by sleep depth or time of the night.

Measurement of the dopaminergic degeneration in Parkinson's disease with [123I] beta-CIT and SPECT. Correlation with clinical findings and comparison with multiple system atrophy and progressive supranuclear palsy

The cocaine derivative [123I] beta-CIT binds with high affinity to dopamine uptake sites in the striatum and can be used to visualize dopaminergic nerve terminals in vivo in the human brain with SPECT. It has been validated that the calculation of a simple ratio of specific/nondisplaceable binding during a period of binding-equilibrium in the striatum about 20 hrs after bolus injection of the tracer gives a strong and reliable index of the binding potential of dopamine uptake sites. Previous studies have shown that the dopaminergic deficit in patients with Parkinson's disease (PD) can clearly be visualized and quantified using this method. Our own results in a group of 113 patients with PD demonstrate a 45% loss of striatal [123I] beta-CIT binding in comparison to age corrected control values. Highly significant correlations of SPECT findings with clinical data obtained from the UPDRS rating scale such as akinesia, rigidity, axial symptoms and activities of daily living are demonstrated, while no correlation is found with tremor. The signal loss in a region comprising the whole striatum ranges from 35% in Hoehn/Yahr stage 1 to over 72% in stage V and is highly significantly correlated to the different stages of disease severity. A comparison of [123I] beta-CIT binding in the striatum contralaterally and ipsilaterally to the affected body side in 29 patients with hemiparkinson shows a loss of striatal binding of 41% contralaterally and 30% ipsilaterally. Results from subregional analyses in caudate and putamen show relative sparing of the caudate nucleus in PD. Data in 9 patients with multiple system atrophy (MSA) and 4 patients with progressive supranuclear palsy (PSP) are similar to the findings in PD although the differences between caudate and putamen are somewhat less marked. These data demonstrate that the dopaminergic nerve cell loss in PD and other disorders with a dopaminergic lesion can be quantified with [123I] beta-CIT and SPECT and that hopefully a preclinical or very early diagnosis is made possible. Such studies might also open the way for a better evaluation of neuroprotective strategies in PD. It does not seem to be possible however to differentiate PD and MSA or PSP with this method in individual cases.

Imaging of dopamine transporters with iodine-123-beta-CIT and SPECT in Parkinson's disease

The aim of the present study was to demonstrate the degeneration of the dopaminergic nigrostriatal pathway in Parkinson's disease by using the cocaine derivative [123I]beta-CIT (2-beta-carbomethoxy-3-beta(4-iodophenyl)-tropane or RTI-55) and SPECT and to relate the findings to the severity of the disease (Hoehn and Yahr scale, H/Y) and to clinical data such as motor score and activities of daily living.

METHODS

Thirteen volunteers and 47 patients with idiopathic Parkinson's disease (PD) of H/Y Stage I-V (I:n = 16, II:n = 6, III:n = 14, IV:n = 9, V:n = 2) were investigated. Acquisitions were performed 2, 4, 16, 20 and 24 hr postinjection. ROIs were drawn over the striatum and the cerebellum. Specific beta-CIT binding was defined as striatal minus cerebellar binding. The ratio of specific over nondisplaceable binding (striatum/cerebellum-1) was determined as well as the percent deviation of this ratio from age-expected control values.

RESULTS

The time-activity curve of striatal [123I]beta-CIT binding demonstrated a maximum around 20 hr postinjection in controls and a peak 4 hr postinjection in PD patients. Ratios differed significantly between the two groups. A significant correlation existed between this ratio and clinical measures. Hemiparkinsonian patients revealed significantly diminished [123I]beta-CIT binding not only contralateral to the clinically affected but also contralateral to the clinically unaffected side. [123I]beta-CIT binding showed a significant decrease in comparison to age-expected values ranging from 36% in H/Y stage 1 to 71% in H/Y stage V.

CONCLUSION

The present study demonstrates that it is possible to visualize and quantify the degeneration of dopaminergic nigrostriatal neurons in PD using [123I]beta-CIT and SPECT with good correlation to clinical parameters.

Dopamine D2 receptor imaging in pituitary adenomas using iodine-123-epidepride and SPECT

Epidepride is a novel benzamide derivative with high affinity for D2 receptors. Epidepride, in its 123I-labeled form, can be used for SPECT imaging of striatal and extrastriatal dopamine D2 receptors. The present study evaluated the usefulness of epidepride and SPECT for in vivo imaging of dopamine receptors in pituitary adenomas.

METHODS

SPECT imaging was performed in 19 patients with pituitary adenomas (among them 9 patients had prolactinoma, 4 acromegaly, 4 clinically nonfunctioning pituitary adenoma, 1 Cushing's disease and 1 Nelson's syndrome) and 7 control subjects 180 min after intravenous bolus injection of 3.9 +/- 1.1 mCi [123I]epidepride. The ratio target/cerebellum minus 1, reflecting specific/ nonspecific binding was used as semiquantitative measure of D2 receptor binding.

RESULTS

Eight of nine prolactinoma patients demonstrated specific binding within the adenoma. The adenoma/ cerebellum ratio 3 hr p.i. showed a wide variation with values from 2.5-33. In three prolactinomas, binding was higher than in the striatum. Specific binding within the lower range of prolactinomas (adenoma/cerebellum ratios 2 and 4.8) could be demonstrated in two of four GH-secreting adenomas. All four nonfunctioning tumors showed specific binding. The adenoma/cerebellum ratio was within the lower range of prolactinomas (5.2-7.5) in three of these patients but extremely high in one (52.3). No specific tracer uptake could be demonstrated in patients with Cushing's disease or Nelson's syndrome. The striatum/cerebellum ratio 3 hr p.i. in pituitary adenoma patients was not significantly different from control subjects (17.3 +/- 5.5 versus 17.8 +/- 6.6; patients versus control subjects).

CONCLUSION

Epidepride appears to be an excellent ligand for in vivo imaging of dopamine D2 receptors in pituitary adenomas. Epidepride SPECT could serve as a predictor for response to dopamine agonist treatment.

Striatal dopamine-2 receptor occupancy in psychotic patients treated with risperidone

Seventeen psychiatric patients (11 with schizophrenia, 5 with other psychotic disorders, and 1 with obsessive-compulsive disorder) were examined by single photon emission computed tomography with 123I-iodobenzamide (IBZM) as tracer. Patients were treated with risperidone in two different dosage groups (3 mg and 8 mg) and haloperidol (10-20 mg) and compared with eight healthy control subjects. There was a statistically significant difference in basal ganglia/frontal cortex ratios of IBZM binding between controls and all treatment groups. A statistically significant difference was also found concerning these ratios and percentage of dopamine D2 receptor occupancy rates between the treatment groups with lowest ratios and highest percentage of D2 receptor occupancy in the group of patients treated with haloperidol, followed by the group treated with 8 mg of risperidone and the group treated with 3 mg of risperidone.

Dopamine D2 receptor binding is reduced in Wilson's disease: correlation of neurological deficits with striatal 123I-iodobenzamide binding

To visualise and quantify dopamine D2 receptor binding in the corpus striatum of patients with neurological Wilson's disease (WD) 123I-Iodobenzamide (IBZM) binding was measured using single photon emission computer tomography (SPECT). Ratios of striatal to frontal countrates were calculated in 8 patients and in 21 healthy control subjects. We found reduced IBZM binding ratios in all patients with WD in comparison to those in controls (1.48 +/- 0.13 vs. 1.73 +/- 0.09). The reduction in IBZM binding was correlated with the overall severity of neurological deficits and the severity of dysarthria (correlation coefficients -0.86 [p < 0.01] and -0.79 [p < 0.01], respectively). When patients of three different subgroups of neurological WD were compared no differences in IBZM binding were found. We conclude that assessing basal ganglia function in vivo using IBZM-SPECT is a valuable diagnostic tool in WD.