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Biomedical subjects

E A Van Royen

Publications and source records attributed to E A Van Royen.

At least 19 recordsLinked to original sources
PubMed1999

Measurement of temporal regional cerebral perfusion with single-photon emission tomography predicts rate of decline in language function and survival in early Alzheimer's disease.

We determined the relationship between regional cerebral blood flow (rCBF) measured with single-photon emission tomography (SPET) and decline in cognitive function and survival in Alzheimer's disease. In a prospective follow-up study, 69 consecutively referred patients with early probable Alzheimer's disease (NINCDS/ADRDA criteria) underwent SPET performed at the time of initial diagnosis using technetium-99m-labelled hexamethylpropylene amine oxime. Neuropsychological function was assessed at baseline and after 6 months and survival data were available on all patients, extending to 5.5 years of follow-up. Lower left temporal (P<0.01) and lower left parietal (P<0.01) rCBF were statistically significantly related to decline in language function after 6 months. The association between left temporal rCBF and survival was also statistically significant (P<0.05) using Cox proportional hazards regression analysis. Performing analysis with quartiles of the distribution, we found a threshold effect for low left temporal rCBF (rCBF<73.7%, P<0. 01) and high risk of mortality. In this lowest quartile, median survival time was 2.7 years (follow-up to 5.2 years), compared with 4.4 years in the other quartiles (follow-up to 5.5 years). Kaplan-Meier survival curves showed statistically significant (P<0. 05, log rank test) survival curves for the lowest versus other quartiles of left temporal rCBF. All results were unaffected by adjustment for age, sex, dementia severity, duration of symptoms, education and ratings of local cortical atrophy. We conclude that left temporal rCBF predicts decline in language function and survival in patients with early probable Alzheimer's disease, with a threshold effect of low rCBF and high risk of mortality.

Aged↗
PubMed1998

The role of renal scintigraphy in the diagnosis and follow-up of unilateral ATN after complete bilateral distal ureteral obstruction as a complication of acute appendicitis.

Acute anuria due to bilateral distal ureteral obstruction developed in two boys, ages 7 and 13, several days after appendectomy, without sonographic signs of hydronephrosis or hydroureters. Decompression was achieved after introduction of ureteric stents. This failed on the left side in one patient, and unilateral acute tubular necrosis (ATN) subsequently developed on that side. Although bilateral decompression was successful in the second patient, ATN had already developed on the left side. In both patients, Tc-99m MAG3 renal scintigraphy proved to be an important tool in diagnosing unilateral ATN and for evaluating the recovery from this rare complication.

Acute Disease↗
PubMed1997

[123I]FP-CIT binds to the dopamine transporter as assessed by biodistribution studies in rats and SPECT studies in MPTP-lesioned monkeys.

[123I]FP-CIT (N-omega-fluoropropyl-2 beta-carbomethoxy-3 beta-(4-iodophenyl)-tropane), a radioiodinated cocaine analogue, was evaluated as an agent for the in vivo labeling of dopamine (DA) transporters by biodistribution studies in rats and by single photon emission computed tomography (SPECT) studies in unilateral 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned monkeys. In rats, intravenous injection of [123I]FP-CIT resulted in high accumulation of radioactivity in the striatum. Less pronounced uptake was seen in brain areas with high densities of serotonergic uptake sites. While striatal uptake of radioactivity after injection of [123I]FP-CIT was displaced significantly by GBR12,909 but not by fluvoxamine, the opposite was observed in brain areas known to be rich of serotonin transporters. Monkeys which were unilaterally treated with neurotoxic doses of MPTP showed severe loss of striatal [123I]FP-CIT uptake at the side of treatment. The results of this study indicate that [123I]FP-CIT, although not being a selective radioligand, binds specifically to the striatal DA transporter in vivo and thus suggest that [123I]FP-CIT promises to be a suitable radioligand for SPECT imaging of DA transporters in humans.

Animals↗
PubMed1997

[123I]beta-CIT single-photon emission tomography in Parkinson's disease reveals a smaller decline in dopamine transporters with age than in controls.

In vivo studies using single-photon emission tomography (SPET) and positron emission tomography have shown an age-related decline in the number of striatal dopamine transporters in healthy subjects. We examined ten healthy subjects and 33 de novo patients with Parkinson's disease (PD) using [123I]2beta-carbomethoxy-3beta-(4-iodophenyl)tropane ([123I]beta-CIT) SPET. A clear age-related loss of dopamine transporters was found in the healthy subjects. In the PD group, controlling for the contribution of disease severity, we found a small (compared with controls) but significant decrease with aging, though only in the ipsilateral regions. This aging effect was especially pronounced in younger patients. We conclude that the use of age-correct SPET data in PD, based on studies with healthy subjects, may lead to an under- or an overestimation of the striatal binding measures.

Adult↗
PubMed1996

In vitro and in vivo characterization of newly developed iodinated 1-[2-[bis(4-fluorophenyl)methoxy]ethyl]piperazine derivatives in rats: limited value as dopamine transporter SPECT ligands.

A series of 1-{2-[bis(4-fluorophenyl)methoxy]ethyl}piperazines (CYD1, 2, 3, 5) with a 4-substituent incorporating a 1-hydroxy-3-iodo-2-propenyl moiety, except CYD2 which lacks the hydroxy, was synthesized as potential in vivo imaging ligands for the dopamine transporter. For two of the piperazine derivatives (CYD3 and 5), possible stereoselectivity was considered as well (both E- and Z-form). Their in vitro potency for inhibition of [3H]dopamine uptake in rat striatal synaptosomes was 10-fold lower than that of GBR 12,909 used as a reference. The highest Ki values were 137 and 101 nM for CYD1E and CYD3E, respectively. Inhibition potency was higher for the E- than for the Z-isomers. In vivo distribution of radioactivity in rats injected with the 123I-labeled CYDs showed preferred striatal uptake for CYD1E and CYD3E as compared to the cerebellum and occipital cortex. Although the E-isomer of CYD3 showed the best in vitro and in vivo binding characteristics, its striatal uptake ratios (maximal value: 2.7 for striatum-to-cerebellum at 4 h p.i.) are too low to consider application in human Single Photon Emission Computed Tomography studies.

Animals↗
PubMed1996

Cardiac 123I-MIBG uptake is affected by variable uptake in reference regions: implications for interpretation in clinical studies.

Cardiac 123I-meta-iodobenzyl guanidine (123I-MIBG) uptake, using the mediastinal region as a reference, is a predictor of outcome in heart failure. Constant uptake in a reference region is required when studying the pharmacotherapeutic effects on the integrity of the cardiac adrenergic system. The aim of this study was to verify the assumption of constant uptake in reference regions and their relation to established predictors of clinical outcome. Planar 123I-MIBG images were obtained in 28 patients with heart failure. The left ventricular ejection fraction correlated with the heart-to-mediastinum (H/M) ratio but not with myocardial 123I-MIBG uptake. Plasma noradrenaline correlated with the H/M ratio, the heart-to-lung (H/L) ratio, mediastinal uptake and age, but not with uptake in the myocardium and lung. Age correlated with the H/M ratio, H/L ratio, mediastinal uptake and lung uptake, but not with myocardial uptake. In a regression model, after the inclusion of age, the H/M ratio and mediastinal uptake were not related to noradrenaline. We conclude that changes in the H/M and H/L ratios are predominantly due to confounding changes in mediastinal uptake or lung uptake. In pharmacological intervention studies, myocardial 123I-MIBG uptake should be assessed using single photon emission tomography or positron emission tomography, which do not rely on reference regions in mediastinum or lung.

3-Iodobenzylguanidine↗
PubMed1995

Diagnosing Alzheimer's disease in elderly, mildly demented patients: the impact of routine single photon emission computed tomography.

Based on the observation of bilateral temporoparietal hypoperfusion in Alzheimer's disease (AD), single photon emission computed tomography (SPECT) is advocated by some as a powerful diagnostic tool in the evaluation of demented patients. We studied whether routine brain SPECT in elderly, mildly demented outpatients increases the a priori diagnostic sensitivity and specificity of a careful clinical examination. 99mTc-HMPAO SPECT imaging was performed in 110 patients for a first evaluation for dementia. A semiquantitative measure of temporoparietal (TP) perfusion was calculated as the ratio of the activity in the temporoparietal cortex to activity in the cerebellum. A diagnosis of probable AD according to the McKhann criteria was made in 68 patients (mean age of 79.3 years) based on the results of a clinical examination, ancillary investigations and a 6-month follow-up. TP perfusion was significantly lower in AD patients than in 18 age-matched, non-demented controls. However, at a specificity of 89%, sensitivity was only 43% for detecting probable AD. The clinicians judged that SPECT had contributed to the final diagnosis in only 8% of the demented patients investigated. Routine brain SPECT in elderly, mildly demented outpatients does not contribute substantially to diagnostic accuracy after a careful clinical examination using current diagnostic criteria. Clinical guidelines have to be developed for the use of SPECT in patients with (suspected) dementia.

Aged↗
PubMed1995

Evaluation of [123I] beta-CIT binding with SPECT in controls, early and late Parkinson's disease.

The main neuropathological feature in Parkinson's disease (PD) is a severe degeneration of the dopaminergic neurons in the substantia nigra resulting in a loss of dopamine in the striatum. Recently, a new radioligand (beta-CIT) for single photon emission computed tomography (SPECT) became available for in vivo imaging of the dopamine transporter on nerve endings of dopaminergic neurons in the striatum. The present results demonstrate that [123I]-beta-CIT SPECT allows a discrimination between early and late PD patients. In our opinion, these preliminary data suggest that [123I]-beta-CIT SPECT should be used from now on in longitudinal studies (such as the DATATOP study) in which the effects of (putative) neuroprotective interventions in PD are monitored.

Adult↗
PubMed1994

Reporting of perfusion/ventilation lung scintigraphy using an anatomical lung segment chart: a prospective study.

This study prospectively evaluated the effect of the consistent use of a previously described anatomical lung segment chart on the interpretation of lung scans. Simultaneous perfusion/ventilation lung scintigraphy was performed in 221 consecutive patients with clinically suspected pulmonary embolism. Lung scans were immediately reported as normal, high probability or non-diagnostic with the use of an anatomical lung segment chart. After at least 6 months, blinded lung scans were randomly read by a panel of nuclear medicine physicians. Initial lung scan reports were classified as normal, high probability or non-diagnostic in 64, 63 and 94 patients, respectively. Overall observer disagreement was 5.9% (95% confidence interval (CI) 3.2-9.8%), while this was 7.8, 3.2 and 7.9% for lung scans that were initially reported as normal, non-diagnostic and high probability, respectively. Reclassification consisted of normal to non-diagnostic (5), non-diagnostic to normal (1), non-diagnostic to high probability (2), and high probability to non-diagnostic scan results (5). From the literature, an overall disagreement of 20% was expected if no chart had been used. In conclusion, this study confirms that the consistent use of a lung segment chart reduces observer disagreement in the reporting of lung scans.

Adolescent↗
PubMed1993

Dosimetry of iodine-123 iodobenzamide in healthy volunteers.

The distribution of the dopamine D2-receptor specific ligand iodine-123 (S)-(-)-2-hydroxy-3-iodo-6-methoxy-N[(1-ethyl-2- pyrrolidinyl)methyl]-benzamide (123I-IBZM) was investigated in human adults from whole-body scans, blood samples and urine collected up to 48 h after injection. Results from the present study performed in six healthy volunteers were combined with those of five volunteers from a previous study. Using the brain, liver, lungs and spleen as source organs, the MIRD method was applied to calculate the absorbed radiation dose of the radioligand in various organs. The thyroid (despite blockage), gallbladder wall, large intestinal walls and spleen received the highest absorbed doses. The average effective dose equivalent of 123I-IBZM for adults was estimated to be 0.034 mSv/MBq. The absorbed dose to the thyroid may be a limiting factor for 123I-IBZM studies in children.

Adult↗
PubMed1993

Quantification of central benzodiazepine receptor binding potential in the brain with 123I-iomazenil SPECT: technical and interobserver variability.

Factors contributing to the quantification of the central benzodiazepine receptor binding potential in vivo using 123I-iomazenil and single photon emission computed tomography (SPECT) were analysed in phantom studies and in volunteers. SPECT was performed with the SME810 multidetector system. The Hoffman three-dimensional brain phantom was used to investigate linearity and reproducibility of SPECT results using different 123I activity concentrations. Dynamic and multislice SPECT scans were performed in nine healthy volunteers between 0 and 270 min after injection of 110 MBq 123I-iomazenil. Displacement studies were performed in three volunteers using 1 mg flumazenil administered intravenously (i.v.) at 250 min postinjection (p.i.). Regions of interest (ROIs) over the cerebral cortex and various subcortical nuclei were either fixed areas based on a stereotaxic brain atlas, or manually drawn, based on 60% isocontour lines. Interobserver variability of the ROI data and ratios derived from those data were estimated for two independent observers. The brain phantom measurements showed linearity with respect to 123I concentration and good reproducibility. The interobserver study showed a reasonable interobserver reliability for the large fixed ROIs. The displacement study showed about 50% displacement in all ROIs. Concentrations of 123I-iomazenil in the brain can be measured reliably with the SME810. Large fixed ROIs based on a stereotaxic atlas may be used reliably for quantification. The level of 4 cm above the cantomeatal line does not provide a useful reference region with a very low central benzodiazepine receptor binding potential.

Adult↗
PubMed1992

Memory complaints, memory disorders and focus localization in patients with partial epilepsy.

Our study aimed at analysing effects of epileptic foci on memory function in patients with partial epilepsy. Twenty-eight patients with spontaneous memory complaints and psychometrically established memory disorders were assessed by 21-channel electroencephalography recorded both during cognitive testing and during 99mTc-HMPAO single photon emission computed tomography (SPECT). Computed tomography (CT) was performed on the same day. None of the epilepsy-related factors (seizure type, seizure frequency, type of epilepsy, age at onset of the seizures, type of antiepileptic treatment) could be related directly to severity or type of memory impairment (classified into the categories 'global', 'verbal' and 'non-verbal'). Remarkably, this study found no significant relationship between EEG focus localization and severity of measured memory impairment. Most areas with hypoperfusion on the SPECT were found in the group with global (severe) amnesia, typically with a right frontal localization. Abnormalities on CT were predominantly found in the same group, however, with a right-sided parietal localization. An unanticipated finding was that the majority of temporal CT and SPECT lesions were found in the group with relatively better memory performance.

Adult↗
PubMed1992

Focus localization in patients with partial epilepsy with 99Tcm-HMPAO SPECT under continuous surface EEG monitoring.

Our study was aimed at determining the validity of 99Tcm-HMPAO single photon emission computed tomography (SPECT) in the localization of the epileptogenic focus by correlating this diagnostic method with other auxiliary investigations such as surface EEG and X-ray transmission computed tomography (CT). Twenty-eight patients with partial epilepsy and spontaneous memory complaints were assessed with a 21-channel EEG recorded during psychometric evaluation of the memory complaints and with a 12-channel EEG during 99Tcm-HMPAO SPECT. No significant agreement was observed for total focus localization by the two EEGs, CT or SPECT. The EEGs were highly reproducible. Frontal and temporal pathology on CT resulted in frontal and temporal cold spots on SPECT on the same side in six patients. In addition, SPECT demonstrated frontal, temporal or posterior temporal-inferior parietal cold spots in nine patients without accompanying pathology on CT. It is concluded that CT and SPECT may provide complementary anatomical and functional information, respectively, to the EEG. Furthermore, SPECT may be complementary to CT in visualizing functional deficits without an anatomical correlate. The value of SPECT studies in partial epilepsy may be improved by increasing the resolution of the SPECT system and by simultaneous EEG monitoring.

Adult↗
PubMed1991

Dynamic SPECT in two healthy volunteers to determine the optimal time for in vivo D2 dopamine receptor imaging with 123I-IBZM using the rotating gamma camera.

Dynamic SPECT was performed in two healthy male volunteers with a single slice brain dedicated camera (Strichman Medical Equipment 810, first study) and a rotating gamma camera (Siemens Dual Rota ZLC37, second study) to obtain information about the optimal imaging time for the dopamine D2 receptor specific ligand 123I-(S)-(-)-2-hydroxy-3-iodo-6-methoxy-N[(1-ethyl-2-pyrrolidinyl) methyl]-benzamide (123I-IBZM). Count rates in the basal ganglia and in several cerebral cortical regions were used to define specific and aspecific binding, respectively. On the basis of the first study, 90-150 min seemed the optimal time for rotating gamma camera 123I-IBZM-SPECT. On the basis of the second study the optimal period was considered to be 60-120 min. It is recommended to apply the same imaging time after injection in a protocol to all patients and volunteers as otherwise a comparison may not be reliable.

Adult↗
PubMed1991

SPECT in early- and late-onset Alzheimer's disease.

We assessed with SPECT the influence of age of onset in Alzheimer's disease in patients who were matched for severity of disease with early and late onset of the disease. Twenty-six patients, severity-matched according to scores on Mini-Mental State Examination, were compared to nine controls. Comparison of the temporoparietal cerebellar ratio (TPC) revealed a statistically significantly lower ratio in the early-onset group compared to the late-onset group of patients. These results are in agreement with other imaging, structural, and neurochemical studies, supporting the view of heterogeneity of Alzheimer's disease according to age of onset.

Aged↗
PubMed1989

14C-urea breath test as a method to detect Campylobacter pylori colonization.

Campylobacter pylori may cause type B gastritis. C. pylori produces urease, and the presence of this enzyme in gastric mucosal biopsies is a marker for colonization with the microorganism. The value of a breath test to detect C. pylori colonization in non-ulcer dyspepsia patients was investigated. We compared the 14C-urea breath test with the culture results obtained from antral mucosal biopsies. The 14C-urea breath test is comparable to culture results in detecting C. pylori colonization.

Bacteriological Techniques↗