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Biomedical subjects

S Eberl

Publications and source records attributed to S Eberl.

At least 19 recordsLinked to original sources
PubMed2006

Results of the pilot study of DIADEM: a comprehensive disease management programme for type 2 diabetes.

AIMS: The purpose of the study was to evaluate the feasibility and preliminary clinical effects of the DIADEM disease management programme for type 2 diabetic patients. METHODS: The study was performed at two test sites (Cardiff, UK: Aachen, Germany) including 137 and 166 patients, respectively. In 16 study centres any patients with type 2 diabetes capable of communicating by phone and able to perform blood pressure, blood glucose or urine glucose self-measurements were included. The maximum programme duration was 6 months at Cardiff and 4 months at Aachen, during which patients were assessed for glycaemic control, cardiovascular risk profile and the presence of complications of diabetes. Data were entered via the internet to a central server. RESULTS: At entry into the programme the patient group in Cardiff had significantly lower mean age (60.3+/-9.4 years versus 64.9+/-8.7 years, p<0.001) and duration of diabetes (6.1+/-5.7 years versus 7.4+/-7.0 years, p<0.05) than in Aachen, however body mass index (31.6+/-5.2 kg/m(2) versus 29.5+/-4.9 kg/m(2), p<0.01), HbA1c (7.7+/-1.2% versus 7.1+/-1.2%, p<0.001) and systolic blood pressure (138.4+/-15.1 mmHg versus 133.5+/-11.5 mmHg, p<0.001) were significantly higher. In contrast, total cholesterol (4.7+/-1.0 mmol/l versus 5.5+/-1.1 mmol/l, p<0.001) was significantly lower in Cardiff compared to Aachen. Following entry into the programme highly significant improvements in HbA1c (Cardiff from 7.7% to 7.1%, p<0.001; Aachen from 7.2% to 6.8%, p<0.05) and total cholesterol concentrations (Cardiff: 4.66-4.46 mmol/l; Aachen: 5.33-5.15 mmol/l; both p<0.05) were observed. There were no significant changes in blood pressure at either site. CONCLUSIONS: Intensive diabetes care was delivered to DIADEM patients and relevant and significant improvements in diabetes care were achieved demonstrating that an IT-based diabetes disease management service can improve care for patients with type 2 diabetes.

Aged↗
PubMed2004

3-Pyridyl ethers as SPECT radioligands for imaging nicotinic acetylcholine receptors.

To develop a suitable single photon emission computed tomography (SPECT) radioligand for neuronal nicotinic acetylcholine receptors (nAChRs) that displays faster in vivo kinetics than 5-[123I]iodo-A-85380, we synthesised the radioiodinated analogue of A-84543. 5-[123I]Iodo-A-84543 was prepared by electrophilic iododestannylation in a modest yield of 23%. In the baboon brain, 5-[123I]iodo-A-85380 displayed a profile consistent with the known distribution of nAChRs, however, 5-[123I]iodo-A-84543 displayed a homogenous uptake with no preferential localisation in regions known to contain nAChRs. To examine the effect of halogen substitution on the 3-pyridyl ether, A-84543, the 5-chloro, 5-bromo and 5-iodo analogues were synthesised and evaluated with respect to nAChR binding. In vitro binding data revealed that halogen substitution at the 5-position of A-84543 was not well tolerated with an increase in halogen size resulting in lower binding towards nAChRs. The 5-chloro analogue 4 displayed highest affinity, Ki =1.3 nM, compared to the 5-bromo and 5-iodo compounds, 5 Ki =3.3 nM and 3 Ki =40.8 nM, respectively. Taken together, these results clearly indicate that 5-[123I]iodo-A-84543 is not suitable for the study of nAChRs in vivo using SPECT.

Animals↗
PubMed2002

Effects of terbutaline in combination with mannitol on mucociliary clearance.

Beta2-agonists and osmotic agents stimulate mucociliary clearance (MCC) via different mechanisms which could potentially interact. The effects of inhaling terbutaline in combination with mannitol on MCC were investigated in nine healthy (aged 19+/-1 yrs) and 11 mild (aged 21+/-4 yrs) asthmatic subjects. Using 99mTc-sulphur colloid radioaerosol and a gamma camera, MCC was studied on four separate days with each of the following interventions: 1) terbutaline or its placebo inhaled 10 min before mannitol (in random, double blind); 2) terbutaline inhaled 5 min after mannitol; and 3) terbutaline inhaled 10 min before the control for mannitol. Lung images were collected over a period of 120 min postintervention and over 150 min in total. The mannitol-induced increase in clearance was transiently inhibited by terbutaline pretreatment and transiently enhanced when terbutaline was administered after mannitol both in asthmatic and healthy subjects. The order of administration of mannitol and terbutaline did not affect the total clearance of radioactive mucus over 140 min from the start of intervention in both groups. The pathways through which terbutaline and mannitol increase mucociliary clearance may transiently interact in an inhibitory or synergistic way, depending on the order of administration. However, this did not affect the overall increase in mucociliary clearance over 140 min.

Administration, Inhalation↗
PubMed2001

Aerosol deposition and clearance measurement: a novel technique using dynamic SPET.

Planar gamma camera scintigraphy is a well-established technique for characterising the deposition and clearance of radiolabelled aerosols. While single-photon emission tomography (SPET) can offer superior assessment of radioaerosol deposition and better differentiation between peripheral and central deposition, the long acquisition times of single-headed SPET have largely prevented its use for measuring clearance or deposition of fast-clearing radioaerosols. This study investigated the feasibility of fast dynamic SPET imaging (1 min/frame) using a three-headed gamma camera to assess the regional and total deposition and clearance of different radioaerosols over a period of 26 min. Six subjects inhaled nebulised technetium-99m diethylene triamine penta-acetic acid radiolabelled aerosols with small and large droplet sizes [mass median aerodynamic diameter (MMAD) 3.2 +/- 0.2 and 6.5 +/- 0.2 microm, span 1.8 and 1.7, respectively] and in normal (0.9%) or hypertonic (7%) saline with controlled breathing on four separate occasions. The penetration indices (PIs) calculated from the SPET data for normal saline were 0.50 +/- 0.04 and 0.36 +/- 0.02 for the small and large droplet sizes, respectively. Consistent with the hygroscopic growth of the hypertonic aerosols, the PIs for hypertonic saline were lower, at 0.43 +/- 0.02 and 0.34 +/- 0.02 for the small and large droplet sizes, respectively. PIs calculated from the planar data showed similar trends, but failed to detect the significant difference seen with SPET between small normal and small hypertonic saline radioaerosols. In conclusion, the feasibility of using fast dynamic SPET for imaging radioaerosol deposition and associated radiolabel clearance in the lung has been successfully demonstrated. The fast SPET was able to reveal important differences in aerosol deposition that were not detected by planar imaging.

Administration, Inhalation↗
PubMed2001

In vivo imaging of nicotinic receptor upregulation following chronic (-)-nicotine treatment in baboon using SPECT.

To quantify changes in neuronal nAChR binding in vivo, quantitative dynamic SPECT studies were performed with 5-[(123)I]-iodo-A-85380 in baboons pre and post chronic treatment with (-)-nicotine or saline control. Infusion of (-)-nicotine at a dose of 2.0 mg/kg/24h for 14 days resulted in plasma (-)-nicotine levels of 27.3 ng/mL. This is equivalent to that found in an average human smoker (20 cigarettes a day). In the baboon brain the regional distribution of 5-[(123)I]-iodo-A-85380 was consistent with the known densities of nAChRs (thalamus > frontal cortex > cerebellum). Changes in nAChR binding were estimated from the volume of distribution (V(d) ) and binding potential (BP) derived from 3-compartment model fits. In the (-)-nicotine treated animal V(d) was significantly increased in the thalamus (52%) and cerebellum (50%) seven days post cessation of (-)-nicotine treatment, suggesting upregulation of nAChRs. The observed 33% increase in the frontal cortex failed to reach significance. A significant increase in BP was seen in the thalamus. In the saline control animal no changes were observed in V(d) or BP under any experimental conditions. In this preliminary study, we have demonstrated for the first time in vivo upregulation of neuronal nAChR binding following chronic (-)-nicotine treatment.

Animals↗
PubMed2001

The 24-h effect of mannitol on the clearance of mucus in patients with bronchiectasis.

STUDY OBJECTIVE: To investigate the acute effect of mannitol on the clearance of mucus, and (1) the 24-h mucus retention, and (2) the mucus clearance rate and lung function 24 h after inhalation of a single dose of mannitol. DESIGN: Clearance of mucus was measured on 3 consecutive days using (99m)Tc-sulfur colloid radioaerosol and a gamma camera. INTERVENTIONS: Mannitol, 330 +/- 68 mg (mean+/- SD), was inhaled using a dry powder inhaler only on day 2. PATIENTS: Eight patients with bronchiectasis (age range, 29 to 70 years). MEASUREMENTS AND RESULTS: On each day, lung images were collected over 2 h and at 24 h. Key findings of the study are as follows: (1) the 24-h retention of mucus was reduced the day after mannitol had been inhaled, compared to the day without mannitol (day 1) in the whole right lung (57.6 +/- 6.2% vs 68.1 +/- 5.9%), central (47.5 +/- 6.7% vs 56.9 +/- 6.5%), intermediate (61.7 +/- 5.6% vs 73.8 +/- 5.5%), and peripheral regions (70.9 +/- 4.3% vs 86.6 +/- 4.6%)(p < 0.02); and (2) mannitol helped patients clear mucus within 2 h that might otherwise take up to 24 h, from the whole right lung and defined regions. However, clearance over 60 min measured 24 h after mannitol inhalation was not significantly different to baseline clearance without mannitol (8.7 +/- 1.9% on day 1 vs 9.7 +/- 3.7% 24 h after mannitol; p > 0.8). The patients maintained the same lung function the day before and after mannitol had been inhaled: FEV(1) (percent predicted), 79 +/- 5 on day 1 vs 80 +/- 5 on day 3; and forced expiratory flow, midexpiratory phase (percent predicted), 50 +/- 6 on day 1 vs 51 +/- 6 on day 3; p > 0.6). CONCLUSIONS: Mannitol inhalation acutely increases clearance of mucus, and this effect extends beyond the acute study period, resulting in decreased mucus retention at 24 h.

Adult↗
PubMed2001

Instrumentation and methodology for quantitative pre-clinical imaging studies.

Radiotracer imaging studies performed on animals have the potential to play a major role in pharmaceutical development, pharmacology studies and basic biochemistry research. Recent developments in instrumentation and imaging methodology make it possible to image and quantify the kinetics of radiolabelled pharmaceuticals in a wide range of animal models from rodents to non-human primates. This article reviews the developments which have led to the current state-of-the-art, including advances in detector technologies, image reconstruction and tracer kinetic modelling. The practical issues specific to animal imaging studies are also discussed. With appropriate instrumentation and rigorous methodology, quantitative pre-clinical imaging has an important role to play in drug development.

Animals↗
PubMed2000

Effect of a short course of rhDNase on cough and mucociliary clearance in patients with cystic fibrosis.

The aim of the study was to measure the effect of a short course of recombinant human deoxyribonuclease I (rhDNase) on ciliary and cough clearance in a group of cystic fibrosis patients, using a radioaerosol and gamma camera technique. Patients were initially randomized to receive either rhDNase (2.5 mg qd) or placebo. Following the measurement of baseline clearance, patients were given a 7-day course of either rhDNase or placebo. The patient then returned on the seventh day for follow-up clearance measurements. This was followed by a 2-week washout period before the whole process was repeated with the alternative inhalation solution. On each of the study days, mucociliary clearance was initially measured for a period of 60 min (IC). This was followed by cough clearance (CC) measurements for 30 min, during which patients were requested to cough a total of 120 times. Post-cough clearance (PCC) was then measured for a further 60 min. Thirteen patients completed the study. Patients' age ranged between 18-38 years, and they had baseline values of FEV(1) of 27-103% of predicted values. Following completion of the course of rhDNase, there was a mean percent increase from baseline of 7.5% for FEV(1) and 5.4% for FVC% (P = 0. 03). There was a small, nonsignificant increase in IC (6.2 +/- 3.6%) on the rhDNase arm compared with the placebo arm (-2.3 +/- 2.9%), P = 0.1. No changes were seen in either CC (1.0 +/- 3.2% [rhDNase] vs. 1.9 +/- 2.4% [placebo], P = 0.9) or PCC (-0.7 +/- 1.5% [rhDNase] vs. 0.9 +/- 1.7% [placebo], P = 0.3). Patients who achieved a 10% or greater improvement in FEV(1) (n = 5) in response to rhDNase did not show any greater change in clearance than nonresponders. In conclusion, we were unable to demonstrate any improvements in either ciliary or cough clearance in response to a short course of rhDNase. The mechanism of action of this drug in vivo remains uncertain.

Administration, Inhalation↗
PubMed2000

The influence of tomograph sensitivity on kinetic parameter estimation in positron emission tomography imaging studies of the rat brain.

We investigated the influence of tomograph sensitivity on reliability of parameter estimation in positron emission tomography studies of the rat brain. The kinetics of two tracers in rat striatum and cerebellum were simulated. A typical injected dose of 10 MBq and a reduced dose of 1 MBq were assumed. Kinetic parameters were estimated using a region of interest (ROI) analysis and two pixel-by-pixel analyses. Striatal binding potential was estimated as a function of effective tomograph sensitivity (S(eff)) using a simplified reference tissue model. A S(eff) value of > or =1% was required to ensure reliable parameter estimation for ROI analysis and a S(eff) of 3-6% was required for pixel-by-pixel analysis. We conclude that effective tomograph sensitivity of 3% may be an appropriate design goal for rat brain imaging.

Animals↗
PubMed2000

Regional mucociliary clearance in patients with cystic fibrosis.

This paper reports on a large retrospective analysis of mucociliary clearance (MCC) studies in a group of 59 patients with cystic fibrosis (CF) and 17 age-matched healthy subjects. As many of the CF patients were studied on multiple occasions, a total of 184 patient studies are presented. MCC was measured using a radioaerosol and gamma camera technique. In addition to whole lung clearance, MCC was measured from the central, intermediate, peripheral, basal, mid and apical regions of the lung. MCC was markedly decreased in the CF patient group. Not only was whole lung clearance (14.2 +/- 1.4% vs. 28.0 +/- 3.7%) impaired, but also clearance from the central (19.1 +/- 1.9% vs. 35.6 +/- 4.3%), intermediate (10.7 +/- 1.6% vs. 25.5 +/- 3.7%), apical (12.4 +/- 2.6% vs. 31.6 +/- 4.6%) and mid (14.0 +/- 1.9% vs. 30.4 +/- 4.0%) regions. Attempts were made to identify factors that may have influenced MCC in both the normal subjects and CF patients. Age, gender, body mass index, patient genotype, penetration index, spontaneous cough, and various lung function parameters were entered into a stepwise multiple regression model, but none of the factors proved to be statistically important in determining MCC. Both intrasubject repeatability and intersubject variability estimates are presented for the patients and normal subjects that had multiple studies. The values were found to be remarkably similar for both CF patients and normal subjects and for both intra- and intersubject repeatability. With marked deviation from normal ranges and good repeatability, the measurement of MCC in CF patients would seem to be a valuable outcome measure for clinical trials involving new pharmaceuticals and physical therapy designed to improve removal of secretions from the airways.

Adolescent↗
PubMed2000

Quantitation of regional cerebral blood flow corrected for partial volume effect using O-15 water and PET: I. Theory, error analysis, and stereologic comparison.

Limited spatial resolution of positron emission tomography (PET) can cause significant underestimation in the observed regional radioactivity concentration (so-called partial volume effect or PVE) resulting in systematic errors in estimating quantitative physiologic parameters. The authors have formulated four mathematical models that describe the dynamic behavior of a freely diffusible tracer (H215O) in a region of interest (ROI) incorporating estimates of regional tissue flow that are independent of PVE. The current study was intended to evaluate the feasibility of these models and to establish a methodology to accurately quantify regional cerebral blood flow (CBF) corrected for PVE in cortical gray matter regions. Five monkeys were studied with PET after IV H2(15)O two times (n = 3) or three times (n = 2) in a row. Two ROIs were drawn on structural magnetic resonance imaging (MRI) scans and projected onto the PET images in which regional CBF values and the water perfusable tissue fraction for the cortical gray matter tissue (hence the volume of gray matter) were estimated. After the PET study, the animals were killed and stereologic analysis was performed to assess the gray matter mass in the corresponding ROIs. Reproducibility of the estimated parameters and sensitivity to various error sources were also evaluated. All models tested in the current study yielded PVE-corrected regional CBF values (approximately 0.8 mL x min(-1) x g(-1) for models with a term for gray matter tissue and 0.5 mL x min(-1) x g(-1) for models with a term for a mixture of gray matter and white matter tissues). These values were greater than those obtained from ROIs tracing the gray matter cortex using conventional H2(15)O autoradiography (approximately 0.40 mL x min(-1) x g(-1)). Among the four models, configurations that included two parallel tissue compartments demonstrated better results with regards to the agreement of tissue time-activity curve and the Akaike's Information Criteria. Error sensitivity analysis suggested the model that fits three parameters of the gray matter CBF, the gray matter fraction, and the white matter fraction with fixed white matter CBF as the most reliable and suitable for estimating the gray matter CBF. Reproducibility with this model was 11% for estimating the gray matter CBF. The volume of gray matter tissue can also be estimated using this model and was significantly correlated with the results from the stereologic analysis. However, values were significantly smaller compared with those measured by stereologic analysis by 40%, which can not be explained by the methodologic errors. In conclusion, the partial volume correction was essential in quantitation of regional CBF. The method presented in this article provided the PVE-corrected regional CBF in the cortical gray matter tissue. This study also suggests that further studies are required before using MRI derived anatomic information for PVE correction in PET.

Animals↗
PubMed2000

Histochemical correlates of (15)O-water-perfusable tissue fraction in experimental canine studies of old myocardial infarction.

UNLABELLED: A method has been proposed to quantitate the myocardial water-perfusable tissue fraction (PTF) in the area of hypoperfused asynergic segments using (15)O-water (H2(15)O) and PET. This study investigated the histochemical correlates of PTF (and perfusable tissue index, PTI) in a canine model of old myocardial infarction. METHODS: Myocardial infarction was produced in 12 mongrel dogs, and PET was performed 1 mo later, providing quantitative parametric images of PTF, regional myocardial blood flow (MBF), and extravascular density from H2(15)O, (15)O-carbon monoxide, and transmission datasets. At the end of scanning, the myocardium was sectioned, and the PET images were compared directly with the corresponding myocardial sections. RESULTS: The distribution of tissue necrosis identified by histochemical staining corresponded well with the defect in PTF but not in MBF. PTF agreed with the equilibrium images of myocardial H2(15)O distribution, obtained after injection of a large bolus of H2(15)O. The defect surface area identified on PTF agreed well quantitatively with the morphometric estimates of the surface area of myocardial infarction. PTI agreed with the absolute proportion of histochemically defined normal myocardium (0.87 +/- 0.09 and 0.83 +/- 0.08, respectively; P < 0.01). Both PTF and PTI decreased significantly in segments of myocardial infarction and showed a significant difference between the transmural and nontransmural myocardial infarction. CONCLUSION: The absolute mass and proportion of histochemically defined noninfarcted tissue may be quantitated with PTF and PTI in the area of myocardial infarction segments.

Animals↗
PubMed1999

Deposition of aqueous aerosol of technetium-99m diethylene triamine penta-acetic acid generated and delivered by a novel system (AERx) in healthy subjects.

Deposition of technetium-99m diethylene triamine penta-acetic acid aqueous radioaerosols generated by a novel aerosol delivery system (AERx) was studied in six healthy subjects using both planar and single-photon emission tomography (SPET) imaging. AERx is a microprocessor-controlled, bolus inhalation device that is actuated at pre-programmed values of inspiratory flow rate and volume. The aims of the study were to determine the effects of posture and inhaled volume upon deposition of the aerosol in the lungs. Each subject inhaled the radioaerosol in two positions (supine vs sitting) and with two inspiratory manoeuvres [vital capacity (VC) vs "fixed volume" of 1 l above functional residual capacity]. Simultaneous transmission-emission planar and tomographic images were acquired. The results showed diffuse deposition of the aerosol in the lung. Neither the breathing manoeuvre nor the posture was found to affect the distribution of the aerosol as measured by the ratio of the activity (counts per pixel) in the peripheral:central (penetration index, PI) or in the apex:base regions of the planar lung images (P>0.1). A small, albeit statistically significant, difference in PI (P<0.03) was found between VC and fixed volume sitting manoeuvres with SPET only. The PI values themselves indicate that the radioaerosol was well distributed in the lung, with the periphery having 45%-64% of the activity of the central region. Superposition of transmission SPET lung outline on emission SPET visually confirmed the excellent peripheral deposition of the aerosol. The AERx system showed high efficiency of delivery, with approximately 50% of the extruded dose in the device depositing in the lung. The uniformity of radioactivity distributed throughout the lung is attributed to the fine particle size (mass median aerodynamic diameter of 2 microm) of the aerosol and the electronic control of aerosol inhalation by the device. In conclusion, the AERx system can be ideal for diffuse aerosol deposition of therapeutic or diagnostic agents and is largely unaffected by inhaled volume and posture. The efficiency of the device device can limit the total radiation exposure of patients and staff administering the radioaerosols, and can make it suitable for delivery of expensive drugs.

Adult↗
PubMed1999

The effect of inhaled mannitol on bronchial mucus clearance in cystic fibrosis patients: a pilot study.

It has been postulated that hypertonic saline (HS) might impair the antimicrobial effects of defensins within the airways. Alternative non-ionic osmotic agents such as mannitol may thus be preferable to HS in promoting bronchial mucus clearance (BMC) in patients with cystic fibrosis (CF). This study reports the effect of inhalation of another osmotic agent, dry powder Mannitol (300 mg), compared with its control (empty capsules plus matched voluntary cough) and a 6% solution of HS on BMC in 12 patients with cystic fibrosis (CF). Mucus clearance was measured using a radioaerosol/gamma camera technique. Post-intervention clearance was measured for 60 min, followed by cough clearance for 30 min. Neither mannitol nor HS improved BMC during the actual intervention period compared with their respective controls. However during the post-intervention measurement there was a significant improvement in BMC for both the mannitol (8.7+/-3.3% versus 2.8+/-0.7%) and HS (10.0+/-2.3% versus 3.5+/-0.8%). There was also a significant improvement in cough clearance with the Mannitol (9.7+/-2.4%) compared with its control (2.5+/-0.8%). Despite premedication with a bronchodilator, a small fall in forced expiratory volume in one second (FEV1) was seen immediately after administration of both the mannitol (7.3+/-2.5%) and HS (5.8+/-1.2%). Values of FEV1 returned to baseline by the end of the study. Inhaled mannitol is a potential mucoactive agent in cystic fibrosis patients. Further studies are required to establish the optimal dose and the long-term effectiveness of mannitol.

Administration, Inhalation↗
PubMed1999

Inhalation of dry powder mannitol improves clearance of mucus in patients with bronchiectasis.

Bronchiectasis is a disease characterized by hypersecretion and retention of mucus requiring physical and pharmacologic treatment. Recently we reported that inhalation of dry powder mannitol markedly increases mucociliary clearance (MCC) in asthmatic and in healthy subjects (Daviskas, E., S. D. Anderson, J. D. Brannan, H. K. Chan, S. Eberl, and G. Bautovich. 1997. Inhalation of dry-powder mannitol increases mucociliary clearance. Eur. Respir. J. 10:2449-2454). In this study we investigated the effect of mannitol on MCC in patients with bronchiectasis. Eleven patients 40 to 62 yr of age inhaled mannitol (approximately 300 mg) from a Dinkihaler. MCC was measured over 90 min, in the supine position, on three occasions involving: mannitol or control or baseline, using a radioaerosol technique. On the control day patients reproduced the breathing maneuvers and the number of coughs induced by the mannitol. Mannitol significantly increased MCC over the 75 min from the start of the intervention compared with control and baseline in the whole right lung, central, and intermediate region. Mean (+/- SEM) clearance with mannitol was 34.0 +/- 5.0% versus 17.4 +/- 3.8% with control and 11.7 +/- 4.4% with baseline in the whole right lung (p < 0.0001). The mean number of coughs induced by mannitol was 49 +/- 11. In conclusion, inhalation of dry powder mannitol increased clearance of mucus and thus has the potential to benefit patients with bronchiectasis.

Administration, Inhalation↗
PubMed1998

Optimized acquisition time and image sampling for dynamic SPECT of Tl-201.

With the recent development in scatter and attenuation correction algorithms, dynamic single photon emission computerized tomography (SPECT) can potentially yield physiological parameters, with tracers exhibiting suitable kinetics such as thallium-201 (Tl-201). A systematic way is proposed to investigate the minimum data acquisition times and sampling requirements for estimating physiological parameters with quantitative dynamic SPECT. Two different sampling schemes were investigated with Monte Carlo simulations: 1) Continuous data collection for total study duration ranging from 30-240 min. 2) Continuous data collection for first 10-45 min followed by a delayed study at approximately 3 h. Tissue time activity curves with realistic noise were generated from a mean plasma time activity curve and rate constants (K1 - k4) derived from Tl-201 kinetic studies in 16 dogs. Full dynamic sampling schedules (DynSS) were compared to optimum sampling schedules (OSS). We found that OSS can reliably estimate the blood flow related K1 and Vd comparable to DynSS. A 30-min continuous collection was sufficient if only K1 was of interest. A split session schedule of a 30-min dynamic followed by a static study at 3 h allowed reliable estimation of both K1 and Vd avoiding the need for a prolonged (>60-min) continuous dynamic acquisition. The methodology developed should also be applicable to optimizing sampling schedules for other SPECT tracers.

Animals↗