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R Dierckx

Publications and source records attributed to R Dierckx.

At least 19 recordsLinked to original sources
PubMed2006

Synthesis and evaluation of a 99mTechnetium labeled chitin-binding protein as potential specific radioligand for the detection of fungal infections in mice.

AIM: Radiopharmaceuticals can be used to exploit differences between microorganisms in order to distinguish fungal from bacterial infection. Chitin, abundant in the cell wall of fungi, is not present in mammalian or bacterial cells and therefore represents a highly specific target to localize fungal infection. In this study, we have examined the potential of chitin-binding protein (CBP21) from Serratia marcescens as a specific radiotracer for the detection of invasive fungal infections. METHODS: CBP21 was labeled with 99mTc via hydrazinonicotinamide (HYNIC) and its characteristics were analyzed. In vitro binding studies with polymorphic chitin forms and microorganisms (fungi as well as bacteria) were performed. In vivo biodistribution of the compound was studied in immunocompromised mice with bacterial and fungal infections in the left and right thigh muscle, respectively, using 99mTc-HYNIC-myoglobin as size-matched control and 67Ga-citrate as positive control. Scintigraphic images were acquired at 1 and 7 h postinjection of the tracer. RESULTS: 99mTc-HYNIC-CBP21 was labeled with a radiochemical yield of 61% and a specific activity of 22.3 MBq/nmol. Highest in vitro binding percentages were found with beta-chitin (86.8+/-2.4%). Binding interactions to fungi were higher than to bacteria (P<0.05). In vivo, best ratios of fungal infection versus bacterial infection were seen at 5 and 7 h (3.6+/-1.2 and 2.9+/-1.4, respectively) postinjection of the tracer. Maximum uptake of the tracer in fungal infections (0.63+/-0.11%ID/g) at 7 h was significantly (P<0.05) higher than uptake seen in bacterial infections (0.34+/-0.11%ID/g) or the uptake of 99mTc-HYNIC-myoglobin (P<0.05) in the same infections (0.35+/-0.11%ID/g, respectively, 0.3+/-0.01%ID/g). CONCLUSIONS: This study shows that 99mTc-HYNIC-CBP21 is able to specifically interact with chitin in vitro. Scintigraphy and postmortem in vivo data indicate that 99mTc-HYNIC-CBP21 is able to distinguish fungal infection from bacterial infection probably due to a specific interaction of the protein with the chitin in the fungal cell wall.

Animals↗
PubMed2005

The effect of citalopram hydrobromide on 5-HT2A receptors in the impulsive-aggressive dog, as measured with 123I-5-I-R91150 SPECT.

PURPOSE: Involvement of the serotonergic system in impulsive aggression has been demonstrated in both human and animal studies. The purpose of the present study was to investigate the effect of citalopram hydrobromide (a selective serotonin re-uptake inhibitor) on the 5-HT(2A) receptor and brain perfusion in impulsive-aggressive dogs by means of single-photon emission computed tomography. METHODS: The binding index of the radioligand (123)I-5-I-R91150 was measured before and after treatment with citalopram hydrobromide in nine impulsive-aggressive dogs. Regional perfusion was measured with (99m)Tc-ethyl cysteinate dimer (ECD). Behaviour was assessed before treatment and again after 6 weeks of treatment. RESULTS: A correlation was found between decreased binding and behavioural improvement in eight out of nine dogs. The 5-HT(2A) receptor binding index was significantly reduced after citalopram hydrobromide treatment in all cortical regions but not in the subcortical area. None of the dogs displayed alterations in perfusion on the post-treatment scans. CONCLUSION: This study supports previous findings regarding the involvement of the serotonergic system in impulsive aggression in dogs in general. More specifically, the effect of treatment on the 5-HT(2A) receptor binding index could be demonstrated and the decreased binding index correlated with behavioural improvement.

Aggression↗
PubMed2005

Compression and reconstruction of sorted PET listmode data.

BACKGROUND: In nuclear medicine data can be stored in histogram or listmode format. The most popular histogram format is the planar projection format. Due to the increase in detector blocks, the improved energy resolution and the trends towards time of flight, dynamic and gated imaging, it can be more appropriate to store the data in listmode format. The size of the storage in this format increases linearly with the number of properties (positions, energy, time info) while the histogram format increases exponentially. However, the datasize of listmode data also increases linearly with the number of coincidences. Due to the high number of counts in 3D PET this will lead to very large datasets. Therefore a good compression algorithm for listmode data is very important. METHODS: A sorting and compression method is proposed to reduce the amount of space needed to store the listmode dataset. One event is represented by one number without any information loss compared to the original listmode file. The next step is to sort all events into an array of increasing numbers. These data are compressed by the gzip routine. One of the advantages of 3D PET listmode reconstructions is that they result in a more uniform resolution across the field of view (FOV), which is not always true for other reconstruction algorithms. This improved resolution is shown for the listmode data of a gamma camera operating in PET mode. RESULTS: First the effect of positional accuracy in the listmode dataset is evaluated by comparing resolution in the reconstructions. It is shown that the highest accuracy is not necessary and a significant reduction in the size of the dataset can be obtained prior to lossless compression. A further reduction can be obtained by using the proposed sorting and compression techniques. It is shown that the storage space decreases linearly with the logarithm of the number of coincidences. The compression obtained by different acquisition matrices was compared. Finally it is shown that the 3D listmode reconstruction of sorted listmode data is faster because of improved cache behaviour. The method can be applied to any kind of listmode data. The compression factors will improve when the ratio of measured events to possible events increases.

Algorithms↗
PubMed2004

Registration accuracy of 153Gd transmission images of the brain.

PURPOSE: The aim of the study was to determine the accuracy of non-rigid nine-parameter image registrations based on 153Gd transmission computed tomography (TCT) images as compared with those based on 99mTc-ethyl cysteinate dimer (ECD) images and to assess whether normalised mutual information (NMI) or count difference (CD) should be used. METHODS: TCT and ECD data were acquired in 25 randomly selected patients. Emission images were registered to an ECD template with a CD cost function. The same registration parameters were applied to the transmission images to create a TCT template. All TCT images were registered to the TCT template and the same registration parameters were applied to the ECD images. The procedure was repeated with NMI as cost function. Accuracy of both ECD-based and TCT-based registrations was assessed by comparing the normalisation parameter values and regional activities in the spatially normalised ECD images, using a mixed-model analysis of variance (ANOVA). Scheffe post hoc tests were performed. RESULTS: No significant differences were found between ECD/CD, ECD/NMI and TCT/CD, suggesting that ECD registration can be done with either CD or NMI, and that TCT registration using CD is equally as accurate as ECD registration. The accuracy of TCT registration with NMI was lower, with discrepancies occurring in the frontal inferior region and the cerebellum. The analysis of normalisation parameters indicated that z-scaling is underestimated and yz-rotation overestimated with TCT/NMI registration. CONCLUSION: We conclude that ECD registrations with CD or NMI are as accurate as TCT registrations with CD and that TCT registrations with NMI should be avoided.

Brain↗
PubMed2003

Regional cerebral blood flow and episodic memory in Parkinson's disease: a single photon emission tomography study.

In this paper we examined 46 nondemented Parkinson's disease (PD) patients by means of perfusion single photon emission computed tomography (SPECT) and neuropsychological testing. The aim was to detect correlations of regional cerebral blood flow with episodic memory performance, using an operator-independent technique for the analysis of SPECT data. A significant positive correlation was found between prefrontal blood flow and episodic memory performances. However, age was the most important determinant of memory scores. Age also correlated significantly negatively with prefrontal perfusion. Our methodology also allowed detection of an inverse correlation of left medial temporal lobe perfusion with the memory score. This had not been found in previous studies and might indicate compensatory mechanisms in the brain of PD patients. It is concluded that episodic memory in nondemented PD patients is most dependent on the effects of aging and that the aging effects on cerebral perfusion in the PD brain parallel to a large extent the findings in normal controls.

Adult↗
PubMed2002

The clinical value of nuclear medicine in the assessment of irradiation-induced and anthracycline-associated cardiac damage.

Two groups of patients, those treated for Hodgkin's disease and breast cancer, are particularly at risk of developing late myocardial damage, since radiotherapy (RT) techniques for both patient groups may include (large) parts of the heart, and adjuvant systemic therapy is frequently administered to these patients, in particular anthracycline-containing chemotherapy. Available literature on the monitoring and prediction of RT-induced and anthracycline-associated cardiac damage using nuclear medicine techniques is presented. Based on relevant studies, the risk of overall cardiac disease post-RT and overt congestive heart failure during anthracycline-containing chemotherapy is probably low. Conventional nuclear medicine imaging, i.e. myocardial perfusion scintigraphy, may be of complementary use to echocardiographical evaluation for routine follow-up after RT with modern techniques, in a subgroup of patients with known cardiovascular risk factors. Left ventricle ejection fraction (LVEF) measurements, as assessed by radionuclide angiography for the monitoring of anthracycline-associated cardiac injury, are not very sensitive and early detection will probably be enhanced by combining LVEF measurements with other cardiac function parameters. Also, it may be expected that nuclear medicine techniques using molecular radioligands will constitute an essential future step in the evaluation of subclinical cardiac injury afforded by the combined effect of RT and cardiotoxic chemotherapy.

Anthracyclines↗
PubMed2002

SPECT neuropsychological activation procedure with the Verbal Fluency Test in attempted suicide patients.

Performance on the Verbal Fluency Test, as a measure of the ability of initiating processes, is reduced in depressed suicidal patients. The hampered results in this prefrontal executive task parallel the reduction in prefrontal blood perfusion and metabolism in depressed subjects. A neuropsychological activation study with the verbal fluency paradigm could evaluate a possible blunted increase in perfusion in the prefrontal cortex in depressed suicidal patients. Twenty clinically depressed patients who had recently attempted suicide and 20 healthy volunteers were included in a single photon emission computed tomography (SPECT) split-dose activation study following a verbal fluency paradigm. Statistical parametric mapping was used to determine voxelwise significant changes. Differences in regional cortical activation between the letter fluency and category fluency tasks in attempted suicide patients were found. These patients showed a blunted increase in perfusion in the prefrontal cortex. Methodological restrictions concerning group uniformity, medication bias and subjective effort of the participants are discussed. Our findings indicate a blunted increase in prefrontal blood perfusion as a possible biological reason for reduced drive and loss of initiative in attempted suicide patients.

Adult↗
PubMed2002

Biodistribution and displacement studies of the selective 5-HT2A receptor antagonist 123I-5-I-R91150 in the normal dog.

There is increasing interest in mapping receptors in vivo by using functional imaging modalities such as single photon emission tomography (SPET) and positron emission tomography (PET). Since SPET is a more accessible functional imaging modality than PET and, overall, it is more economical, radioligands suitable for this technique are in greater demand. Recently, 123I-5-I-R91150, a radioligand with high selectivity and affinity for 5-HT(2A) receptors in the brain, was introduced for SPET. This study reports on the whole-body distribution and brain uptake of the selective 123I-5-I-R91150 ligand in four normal dogs. The frontal to cerebellar ratio of uptake in time was determined in three dogs. Time-activity curve of venous blood was determined in one dog. Maximal global brain uptake was found at 10-60 min post-injection. Higher brain uptake was noted in the frontal cortical areas compared to the cerebellum. The frontal-cerebellar ratio reached the highest values at 90-180 min. Reversibility and pharmacological selectivity of ligand binding was demonstrated through displacement and blocking studies with the 5-HT(2A) receptor antagonist ketanserin. This study demonstrates that the specific 5-HT(2A) iodinated ligand can be used for imaging and semi-quantification of the 5-HT(2A) receptors in the canine brain in vivo by using SPET.

Animals↗
PubMed2001

Non-uniform versus uniform attenuation correction in brain perfusion SPET of healthy volunteers.

Although non-uniform attenuation correction (NUAC) can supply more accurate absolute quantification, it is not entirely clear whether NUAC provides clear-cut benefits in the routine clinical practice of brain SPET imaging. The aim of this study was to compare the effect of NUAC versus uniform attenuation correction (UAC) on volume of interest (VOI)-based semi-quantification of a large age- and gender-stratified brain perfusion normal database. Eighty-nine healthy volunteers (46 females and 43 males, aged 20-81 years) underwent standardised high-resolution single-photon emission tomography (SPET) with 925 MBq 99mTc-ethyl cysteinate dimer (ECD) on a Toshiba GCA-9300A camera with 153Gd or 99mTc transmission CT scanning. Emission images were reconstructed by filtered back-projection and scatter corrected using the triple-energy window correction method. Both non-uniform Chang attenuation correction (one iteration) and uniform Sorenson correction (attenuation coefficient 0.09 cm(-1)) were applied. Images were automatically reoriented to a stereotactic template on which 35 predefined VOIs were defined for semi-quantification (normalisation on total VOI counts). Small but significant differences between relative VOI uptake values for NUAC versus UAC in the infratentorial region were found. VOI standard deviations were significantly smaller for UAC, 4.5% (range 2.6-7.5), than for NUAC, 5.0% (2.3-9.0) (P<0.01). Higher filter roll-off values of the transmission reconstruction filter increased noise in the emission images and altered estimated cortical attenuation coefficients as well as uptake values. In conclusion, semi-quantification based upon reconstruction with UAC results in very similar 99mTc-ECD uptake values in healthy volunteers to those obtained with NUAC, although values for the infratentorial region are slightly lower. NUAC produces a slight increase in inter-subject variability. Further study is necessary in various patient populations to establish the full clinical impact of NUAC in brain perfusion SPET.

Adult↗
PubMed2001

Transfer of normal 99mTc-ECD brain SPET databases between different gamma cameras.

A stereotactic, normal perfusion database is imperative for optimal clinical brain single-photon emission tomography (SPET). However, interdepartmental use of normal data necessitates accurate transferability of these data sets. The aim of this study was to investigate transfer of three normal perfusion databases obtained in the same large population of healthy volunteers who underwent sequential scanning using multihead gamma cameras with different resolution. Eighty-nine healthy adults (46 females, 43 males; aged 20-81 years) were thoroughly screened by history, biochemistry, physical and full neurological examination, neuropsychological testing and magnetic resonance imaging. After injection of 925 MBq technetium-99m labelled ethyl cysteinate dimer (ECD) under standard conditions, 101 scans were acquired from all subjects (12 repeat studies) on a triple-head Toshiba GCA-9300A (measured average FWHM 8.1 mm). Ninety-one sequential scans were performed on a dual-head Elscint Helix camera (FWHM 9.6 mm) and 22 subjects also underwent imaging on a triple-head Prism 3000 (FWHM 9.6 mm). Images were transferred to the same processing platform and reconstructed by filtered back-projection with the same Butterworth filter (order 8, cut-off 0.9 cycles/cm) and uniform Sorensen attenuation correction (mu = 0.09). After automated rigid intrasubject registration, all subjects were automatically reoriented to a stereotactic template by a nine-parameter affine transformation. The databases were analysed using 35 predefined volumes of interest (VOIs) with normalisation on total VOI counts. For comparison, the high-resolution data were smoothed with a 3D Gaussian kernel to achieve more similar spatial resolution. Hoffman phantom measurements were conducted on all cameras. Partial volume effects after smoothing varied between -6.5% and 10%, depending on VOI size. Between-camera reproducibility was 2.5% and 2.7% for the Toshiba camera versus the Helix and the Prism database, respectively. The highest reduction in between-camera variability was achieved by resolution adjustment in combination with linear washout correction and a Hoffman phantom-based correction. In conclusion, transfer of normal perfusion data between multihead gamma cameras can be accurately achieved, thereby enabling widespread interdepartmental use, which is likely to have a positive impact on the diagnostic capabilities of clinical brain perfusion SPET.

Adult↗
PubMed2001

99mTc-ECD brain perfusion SPET: variability, asymmetry and effects of age and gender in healthy adults.

Reliable and high-resolution reference data for regional cerebral blood flow measured with single-photon emission tomography (SPET) are necessary for optimal clinical and research use. Therefore, a large dataset of normal technetium-99m labelled ethylene cysteine dimer (ECD) perfusion SPET in carefully screened healthy volunteers with an age range spanning six decades was created, with correction for non-uniform attenuation and scatter and based on an anatomically standardised analysis. Eighty-nine healthy volunteers, stratified for gender (46 females, 43 males; age 20-81 years), were included. Twelve volunteers underwent repeated 99mTc-ECD SPET after 2.5+/-2.3 weeks. An automated whole-brain volume of interest analysis with MANOVA as well as voxelwise analysis using SPM99 was conducted. Average intersubject variability was 4.8% while intrasubject reproducibility was 3.0%. An age-related decline in tracer uptake was found in the anterior cingulate gyrus, bilateral basal ganglia, left prefrontal, left lateral frontal and left superior temporal and insular cortex (all P=0.001-0.02). There was an overall increase in right/left asymmetry with age, which was most pronounced in the frontal and temporal neocortex. The most significant correlations between AI and age decade were found in the prefrontal (R=0.35, P=0.001) and superior temporal neocortex (R=0.43, P<0.001). Women had significantly higher uptake in the right parietal cortex (P<0.001), while men showed higher uptake in the cerebellum and the left anterior temporal and orbitofrontal cortex (all P<0.01). This normative dataset allows age- and gender-specific patient and group assessment of 99mTc-ECD perfusion SPET under a wide variety of clinical circumstances in relation to normal variations and highlights the importance of both age- and gender-specific normal datasets for optimal analysis sensitivity.

Adult↗
PubMed2001

Non-invasive methods for absolute cerebral blood flow measurement using 99mTc-ECD: a study in healthy volunteers.

Radionuclide angiography with technetium-99m ethyl cysteinate dimer (ECD) allows non-invasive estimation of absolute cerebral blood flow (CBF), either by graphical Patlak-Gjedde analysis (PGA) or by spectral analysis (SA). Other methods estimate CBF by means of single-point arterial or venous sampling. The aim of this study was to evaluate radionuclide scanning and single-point venous sampling as potential clinical non- to minimally invasive methods for CBF determination in a large set of carefully screened healthy volunteers over the adult age range. Eighty-three carefully screened healthy volunteers (20-81 years, 43 males, 40 females) underwent planar radionuclide angiography with 925 MBq 99mTc-ECD. After correction for camera dead-time loss, hemispheric CBF was calculated from brain perfusion indices (BPI): BPI(G) for PGA and BPI(S) for SA. Of the volunteers, 49 also underwent venous sampling 6 min post injection, from which the lipophilic octanol extraction fraction and hemispheric brain fractionation index (BFI) were determined. All datasets were correlated and evaluated as a function of age and gender. Intrasubject variability for the BPI measurements was assessed in 11 volunteers by repeat study within 2 weeks of the first acquisition. Graphical and spectral analysis BPIs were strongly correlated (R=0.846, P<0.00001). This correlation coefficient increased to R=0.903 for the 74 cases in which graphical analysis was not hampered by temporal tracer retention in cervicobrachial venous valves. The BFI was weakly correlated to both BPI indices (BPI(G): R=0.34, P=0.02; BPI(S): R=0.31, P=0.04). The right hemisphere showed significant asymmetry for BPI(S) (AI=2.7%+/-4.3%, P<0.001), in correspondence with previous 99mTc-ECD data. BPI(G), BPI(S) and BFI were all inversely related to age, with an increased gradient after the age of 55 years, while there was no significant gender difference. The ratio of BPI(G) to BIP(S), which is a measure of the cerebral extraction fraction for 99mTc-ECD, was not dependent on age. Intersubject variability was 15.5% for both radionuclide scanning-based methods and 18.2% for venous sampling, and in all cases was independent of age. A much lower intrasubject variability was observed for BPI(S) (7.2%) than for BPI(G) (12.6%). This study provides reference values for normal perfusion indices assessed by graphical and spectral analysis. The results also indicate that spectral analysis allows the most reproducible estimate of hemispheric perfusion by means of an operator-independent and objective approach. Whereas accurate calibration of normal BPI(S) values to hemispheric CBF with established methods needs to be performed, non-invasive calculation of regional absolute CBF using 99mTc-ECD is possible by application of a linearisation algorithm.

Adult↗
PubMed2001

Fibrinogen and C-reactive protein on admission as markers of final infarct size after primary angioplasty for acute myocardial infarction.

BACKGROUND: In acute myocardial infarction (AMI) treated conservatively or with thrombolysis, marked increases of C-reactive protein (CRP) and fibrinogen have been observed. No data are however available concerning a possible relation between CRP and fibrinogen levels on admission and markers of infarct size after obtaining thrombolysis in myocardial infarction (TIMI) flow III by primary angioplasty. METHODS: We studied 34 patients with a first AMI (29 men, mean age 54+/-11 years) who were treated with primary angioplasty (TIMI flow III in all patients, no concomitant treatment with glycoprotein IIb-IIIa antagonists) within 6 h of onset of pain. CRP and fibrinogen levels on admission were determined and related to the following markers of infarct size: peak creatine kinase MB (CKMB) levels, radionuclide left ventricular ejection fraction (LVEF) at discharge and thallium-201 single-photon emission computed tomography (SPECT) infarct size at 1 month. RESULTS: Median CRP levels were 0.4 mg/dl (range 0.09-3 mg/dl), median fibrinogen levels 412 mg/dl (range 198-679 mg/dl), mean CKMB was 178+/-151 U/l, mean LVEF 52+/-8% and mean thallium-201 infarct size 7+/-6%. Although CRP levels were related to fibrinogen levels on admission (r=0.56, P=0.002), only fibrinogen levels were related to markers of infarct size (r=0.58, P=0.001 for CKMB, r=-0.44, P=0.01 for LVEF and r=0.64, P=0.001 for thallium-201 infarct size). No relation was found between CRP or fibrinogen levels on admission and the extent of coronary artery disease or the myocardial area at risk. In multiple regression analysis, the relation between fibrinogen and markers of infarct size was independent of CRP levels and the duration of pain on admission. CONCLUSIONS: These findings indicate a relation between fibrinogen levels on admission and myocardial infarct size in patients treated with primary angioplasty for AMI. This relation seems to be independent of CRP levels and the duration of pain on admission. If confirmed in larger patient populations, fibrinogen levels on admission could have an important value for risk stratification and more aggressive reduction of infarct size in patients who are treated with primary angioplasty.

Acute Disease↗
PubMed2001

Differential regional cerebral uptake of (18)F-fluoro-2-deoxy-D-glucose in Alzheimer's disease and frontotemporal dementia at initial diagnosis.

In this paper, the cerebral uptake of (18)F-fluoro-2-deoxy-D-glucose (FDG) was studied in a relatively small group of patients suffering from either clinically diagnosed Alzheimer's disease (AD) or frontotemporal dementia during the initial differential diagnostic workup. The image analysis was done visually and semiquantitatively using three different reference regions. Visual analysis confirmed earlier literature findings on the distribution of decreased FDG uptake and demonstrated prevalent asymmetric patterns in both groups. Only semiquantitative analysis using the sensorimotor cortex as a reference region confirmed the visual findings. Moreover, there were no differences in medial temporal lobe activities between both groups, and there was no correlation of medial temporal lobe activity with dementia severity. In the AD group, a correlation of parietal FDG uptake with MMSE scores was found.

Adult↗
PubMed2001

Automated stereotactic standardization of brain SPECT receptor data using single-photon transmission images.

UNLABELLED: Intra- or intersubject registration of anatomically poorly defined SPECT data, such as in neuroreceptor imaging, is important for longitudinal or group analysis. However, accurate registration is difficult with only emission CT (ECT) data. We investigated fully automated registration using transmission CT (TCT) data as an intermediary image set. METHODS: The accuracy of TCT registration was compared to that of ECT registration for four types of data: gray-matter distribution (with [99mTc]ethylcysteinate dimer (ECD)), neocortical distribution (with [123I]R91150, a highly specific 5-HT2a receptor ligand), and striatal distribution of the D2-receptor ligand (with [123I]iodobenzamide (IBZM)) and the dopamine transporter ligand (with [123I]2beta-carbomethoxy-3beta-(4-fluorophenyl)tropane (CIT)). In total, 10 datasets of the various study types were used, all collected on a Toshiba GCA9300 gamma camera with super-high-resolution fanbeam collimators and 3 x 370 MBq of 153Gd transmission sources (4-min sequential TCT scanning for receptor studies and 20-min simultaneous scanning for [99mTc]ECD studies). Per dataset, 15 random misalignments of 9 rigid-body parameters (translation, rotation, and anisotropic scaling) were conducted. All coregistrations were done twice, both to the subject's original scan and to a study-specific template. This was done manually by two independent experienced observers and with three automated voxel similarity algorithms: mutual information (M.I.), count difference (C.D.), and uniformity index (U.I.). As an outcome measure, the impact of misregistration on semiquantification for the various study types was established. RESULTS: TCT matching allowed registration within 3.3 mm, 2.4 degrees, and 1.2% scaling (mean squared values for all directions) with an overall accuracy decrease in the following order: C.D. > M.I. > manual > U.I. For [99mTc]ECD and [123I]IBZM, TCT registration was as accurate as ECT registration, while it was far superior for the other receptor data types, especially for abnormal studies. The automated TCT registration accuracy corresponded to average quantification errors of 2.9% ([99mTc]ECD), 4.2% ([123I]BZM), 5.7% ([123I]R91150), and 6.1% ([123I]beta-CIT). CONCLUSION: Fully automated registration through intermediary TCT images is clinically feasible, fast, and accurate. In addition to nonuniform attenuation correction, TCT scanning therefore allows coregistration for group comparisons of SPECT receptor data on a standardized or pixel-by-pixel basis.

Adolescent↗