Ovariectomy-induced depressive-like behavior and brain glucose metabolism changes in female rats are not affected by chronic mild stress.

The increased incidence of depression in women going through peri-menopause suggests that fluctuations in estrogen levels may increase the risk of developing depression. Nonetheless, this psychiatric disorder is likely to be multifactorial and consequently an additional trigger may be needed to induce depression in this population. Stress could be such a trigger. We therefore investigated the effect of ovarian estrogen depletion and chronic mild stress (CMS) on depressive-like behavior and brain metabolism in female rats. Approximately 2 and 9 weeks after estrogen depletion by ovariectomy, behavioral changes were assessed in the open-field test and the forced swim test, and brain metabolism was measured with [18F]FDG PET imaging. A subset of animals was subjected to a 6-weeks CMS protocol starting 17 days after ovariectomy. Short-term estrogen depletion had a significant effect on brain metabolism in subcortical areas, but not on behavior. Differences in depressive-like behavior were only found after prolonged estrogen depletion, leading to an increased immobility time in the forced swim test. Prolonged estrogen depletion also resulted in an increase in glucose metabolism in frontal cortical areas and hippocampus, whereas a decrease glucose metabolism was found in temporal cortical areas, hypothalamus and brainstem. Neither short-term nor prolonged estrogen depletion caused anxiety-like behavior. Changes in body weight, behavior and brain glucose metabolism were not significantly affected by CMS. In conclusion, ovarian estrogen depletion resulted in changes in brain metabolism and depressive-like behavior, but these changes were not enhanced by CMS.

Noise reduction using a Bayesian penalized-likelihood reconstruction algorithm on a time-of-flight PET-CT scanner.

PURPOSE: Q.Clear is a block sequential regularized expectation maximization (BSREM) penalized-likelihood reconstruction algorithm for PET. It tries to improve image quality by controlling noise amplification during image reconstruction. In this study, the noise properties of this BSREM were compared to the ordered-subset expectation maximization (OSEM) algorithm for both phantom and patient data acquired on a state-of-the-art PET/CT. METHODS: The NEMA IQ phantom and a whole-body patient study were acquired on a GE DMI 3-rings system in list mode and different datasets with varying noise levels were generated. Phantom data was evaluated using four different contrast ratios. These were reconstructed using BSREM with different ß-factors of 300-3000 and with a clinical setting used for OSEM including point spread function (PSF) and time-of-flight (TOF) information. Contrast recovery (CR), background noise levels (coefficient of variation, COV), and contrast-to-noise ratio (CNR) were used to determine the performance in the phantom data. Findings based on the phantom data were compared with clinical data. For the patient study, the SUV ratio, metabolic active tumor volumes (MATVs), and the signal-to-noise ratio (SNR) were evaluated using the liver as the background region. RESULTS: Based on the phantom data for the same count statistics, BSREM resulted in higher CR and CNR and lower COV than OSEM. The CR of OSEM matches to the CR of BSREM with ß = 750 at high count statistics for 8:1. A similar trend was observed for the ratios 6:1 and 4:1. A dependence on sphere size, counting statistics, and contrast ratio was confirmed by the CNR of the ratio 2:1. BSREM with ß = 750 for 2.5 and 1.0 min acquisition has comparable COV to the 10 and 5.0 min acquisitions using OSEM. This resulted in a noise reduction by a factor of 2-4 when using BSREM instead of OSEM. For the patient data, a similar trend was observed, and SNR was reduced by at least a factor of 2 while preserving contrast. CONCLUSION: The BSREM reconstruction algorithm allowed a noise reduction without a loss of contrast by a factor of 2-4 compared to OSEM reconstructions for all data evaluated. This reduction can be used to lower the injected dose or shorten the acquisition time.

NEMA NU 2-2007 performance characteristics of GE Signa integrated PET/MR for different PET isotopes.

BACKGROUND: Fully integrated PET/MR systems are being used frequently in clinical research and routine. National Electrical Manufacturers Association (NEMA) characterization of these systems is generally done with 18F which is clinically the most relevant PET isotope. However, other PET isotopes, such as 68Ga and 90Y, are gaining clinical importance as they are of specific interest for oncological applications and for follow-up of 90Y-based radionuclide therapy. These isotopes have a complex decay scheme with a variety of prompt gammas in coincidence. 68Ga and 90Y have higher positron energy and, because of the larger positron range, there may be interference with the magnetic field of the MR compared to 18F. Therefore, it is relevant to determine the performance of PET/MR for these clinically relevant and commercially available isotopes. METHODS: NEMA NU 2-2007 performance measurements were performed for characterizing the spatial resolution, sensitivity, image quality, and the accuracy of attenuation and scatter corrections for 18F, 68Ga, and 90Y. Scatter fraction and noise equivalent count rate (NECR) tests were performed using 18F and 68Ga. All phantom data were acquired on the GE Signa integrated PET/MR system, installed in UZ Leuven, Belgium. RESULTS: 18F, 68Ga, and 90Y NEMA performance tests resulted in substantially different system characteristics. In comparison with 18F, the spatial resolution is about 1 mm larger in the axial direction for 68Ga and no significative effect was found for 90Y. The impact of this lower resolution is also visible in the recovery coefficients of the smallest spheres of 68Ga in image quality measurements, where clearly lower values are obtained. For 90Y, the low number of counts leads to a large variability in the image quality measurements. The primary factor for the sensitivity change is the scale factor related to the positron emission fraction. There is also an impact on the peak NECR, which is lower for 68Ga than for 18F and appears at higher activities. CONCLUSIONS: The system performance of GE Signa integrated PET/MR was substantially different, in terms of NEMA spatial resolution, image quality, and NECR for 68Ga and 90Y compared to 18F. But these differences are compensated by the PET/MR scanner technologies and reconstructions methods.

Adults with congenital heart disease: ready for mobile health?

PURPOSE: Mobile health (mHealth) could improve the outcome of grown-up patients with congenital heart disease (GUCH) and reduce their emergency care utilisation. Inappropriate use of mHealth, however, can lead to data overload for professionals and unnecessary data collection for patients, increasing the burden for both. We aimed to determine the clinical characteristics of patients with high emergency care utilisation and to test whether these patients were willing to start using mHealth. METHODS: Clinical characteristics and emergency care utilisation of consecutive GUCH patients who visited one of the two participating cardiologists at the outpatient clinic of the Academic Medical Centre in Amsterdam were studied retrospectively. All patients were approached to fill in an mHealth questionnaire. A frequency of three or more emergency visits in 5 years was defined as high emergency care utilisation. RESULTS: In total, 202 consecutive GUCH patients who visited one of the two participating cardiologists were studied. Median age was 41 years, 47% were male, and 51% were symptomatic. In the previous 5 years, 134 emergency visits were identified. Of all patients, 8% had high emergency care utilisation. High emergency care utilisation was associated with patients being symptomatic, using antiarrhythmic drugs or diuretics. In total, 75% of all patients with high emergency care utilisation were willing to start using mHealth. CONCLUSION: GUCH patients who are symptomatic, those on antiarrhythmic drug therapy and those on diuretics are suitable candidates for enrolment in future mHealth initiatives because of both high care utilisation and high motivation to start using mHealth.

First real-world experience with mobile health telemonitoring in adult patients with congenital heart disease.

BACKGROUND: Arrhythmias and heart failure are common and invalidating sequelae in adult patients with congenital heart disease (CHD). Mobile health (m-Health) enables daily monitoring and a timely response that might prevent deterioration. We present an observational prospective registry to evaluate feasibility of an m­Health telemonitoring program for managing arrhythmia, heart failure and blood pressure in symptomatic adults with CHD. METHODS: Symptomatic adult patients with CHD are enrolled in an m­Health telemonitoring program, which evaluates single-lead ECG, blood pressure and weight measurements. In case of symptoms extra measurements could be performed. Data are collected by mobile apps, matched with individualised thresholds. Patients are contacted if thresholds were exceeded or if arrhythmias were found, for treatment adjustments or reassurance. Data on emergency care utilisation, hospitalisation and patient-reported outcome measures are used to assess quality of life and self-management. RESULTS: 129 symptomatic CHD patients were invited to participate, 55 participated. Reasons for refusing consent included too time consuming to participate in research (30) and to monitor vital signs (14). At baseline 22 patients were in New York Heart Association class ≥ II heart failure, 43 patients had palpitations or documented arrhythmias, and 8 had hypertension. Mean follow-up was 3.0 months, one patient dropped out, and adherence was 97%. CONCLUSION: The first results indicate that this program is feasible with high adherence.

eHealth in patients with congenital heart disease: a review.

INTRODUCTION: Mobile health (mHealth), an advanced form of eHealth is expected to drastically change the field of traditional healthcare in the near future as wearables and mobile applications are rapidly increasing in number. The majority of patients with congenital heart disease (CHD) now reach adulthood and this relative young patient population seems particularly suited for mHealth, as they require lifelong follow-up, experience high morbidity burden, and were raised in this digital era. In patients with acquired heart disease the potential of eHealth has been demonstrated, yet data are still inconclusive. Areas covered: In this review of the current literature we evaluated the effect of various eHealth interventions in patients with CHD. Our search resulted in a mere 10 studies, which comprised mostly of children or adolescents with severe CHD. Home-monitoring of saturation and weight through mHealth was found to be beneficial in patients after palliation procedures, and video conferencing was found to have a positive effect on anxiety and healthcare utilization. Expert commentary: Due to high morbidity and mortality in patients with CHD and the promising results of eHealth interventions, further research is desperately needed.

Comparison of diagnostic accuracy of (111)In-pentetreotide SPECT and (68)Ga-DOTATOC PET/CT: A lesion-by-lesion analysis in patients with metastatic neuroendocrine tumours.

OBJECTIVES: To compare the diagnostic accuracy of (111)In-pentetreotide-scintigraphy with (68)Ga-DOTATOC-positron emission tomography (PET)/computed tomography (CT) in patients with metastatic-neuroendocrine tumour (NET) scheduled for peptide receptor radionuclide therapy (PRRT). Incremental lesions (ILs) were defined as lesions observed on only one modality. METHODS: Fifty-three metastatic-NET-patients underwent (111)In-pentetreotide-scintigraphy (24 h post-injection; planar+single-photon emission CT (SPECT) abdomen) and whole-body (68)Ga-DOTATOC-PET/CT. SPECT and PET were compared in a lesion-by-lesion and organ-by-organ analysis, determining the total lesions and ILs for both modalities. RESULTS: Significantly more lesions were detected on (68)Ga-DOTATOC-PET/CT versus (111)In-pentetreotide-scintigraphy. More specifically, we observed 1,098 lesions on PET/CT (range: 1-105; median: 15) versus 660 on SPECT (range: 0-73, median: 9) (p<0.0001), with 439 PET-ILs (42/53 patients) and one SPECT-IL (1/53 patients). The sensitivity for PET/CT was 99.9 % (95 % CI, 99.3-100.0), for SPECT 60.0 % (95 % CI, 48.5-70.2). The organ-by-organ analysis showed that the PET-ILs were most frequently visualized in liver and skeleton. CONCLUSION: Ga-DOTATOC-PET/CT is superior for the detection of NET-metastases compared to (111)In-pentetreotide SPECT. KEY POINTS: Somatostatin receptor PET is superior to SPECT in detecting NET metastases. PET is the scintigraphic method for accurate depiction of NET tumour burden. The sensitivity of PET is twofold higher than the sensitivity of SPECT.

Fabrication of hybrid molecular devices using multi-layer graphene break junctions.

We report on the fabrication of hybrid molecular devices employing multi-layer graphene (MLG) flakes which are patterned with a constriction using a helium ion microscope or an oxygen plasma etch. The patterning step allows for the localization of a few-nanometer gap, created by electroburning, that can host single molecules or molecular ensembles. By controlling the width of the sculpted constriction, we regulate the critical power at which the electroburning process begins. We estimate the flake temperature given the critical power and find that at low powers it is possible to electroburn MLG with superconducting contacts in close proximity. Finally, we demonstrate the fabrication of hybrid devices with superconducting contacts and anthracene-functionalized copper curcuminoid molecules. This method is extendable to spintronic devices with ferromagnetic contacts and a first step towards molecular integrated circuits.

Does 11C-choline PET-CT contribute to multiparametric MRI for prostate cancer localisation?

BACKGROUND AND PURPOSE: The aim of this work was to determine whether 11C-choline positron emission tomography (PET)-computed tomography (CT) makes a positive contribution to multiparametric magnetic resonance imaging (MRI) for localisation of intraprostatic tumour nodules. PATIENTS AND METHODS: A total of 73 patients with biopsy-proven intermediate- and high-risk prostate cancer were enrolled in a prospective imaging study consisting of T2-weighted (T2w), dynamic contrast-enhanced (DCE) and diffusion-weighted (DW) MRI and 11C-choline PET-CT before radical prostatectomy. Cancerous regions were delineated on the whole-mount prostatectomy sections and on the different MRI modalities and analysed in 24 segments per patient (3 sections, 8 segments each). To analyse PET-CT images, standardized uptake values (SUV) were calculated per segment. RESULTS: In total, 1,752 segments were analyzed of which 708 (40.4%) were found to be malignant. A high specificity (94.7, 93.6 and 92.2%) but relatively low sensitivity (31.2, 24.9 and 44.1%) for tumour localisation was obtained with T2w, DCE and DW MRI, respectively. Sensitivity values significantly increased when combining all MRI modalities (57.2%). For PET-CT, mean SUVmax of malignant octants was significantly higher than mean SUVmax of benign octants (3.68±1.30 vs. 3.12±1.02, p<0.0001). In terms of accuracy, the benefit of adding PET-CT to (multiparametric) MRI was less than 1%. CONCLUSION: The additional value of 11C-choline PET-CT to MRI in localising intraprostatic tumour nodules is limited, especially when multiparametric MRI is used.

Preclinical evaluation of [(18)F]JNJ42259152 as a PET tracer for PDE10A.

Phosphodiesterase-10A (PDE10A) is implicated in several neuropsychiatric disorders involving basal ganglia neurotransmission, such as schizophrenia, obsessive-compulsive disorder and Huntington's disease. To confirm target engagement and exposure-occupancy relationships of clinical candidates for treatment, and to further explore the in vivo biology of PDE10A, non-invasive imaging using a specific PET ligand is warranted. Recently we have reported the in vivo evaluation of [(18)F]JNJ41510417 which showed specific binding to PDE10A in rat striatum, but with relatively slow kinetics. A chemically related derivative JNJ42259152 was found to have a similar in vivo occupancy, but lower lipophilicity and lower PDE10A in vitro inhibitory activity compared to JNJ41510417. (18)F-labeled JNJ42259152 was therefore evaluated as a potential PDE10A PET radiotracer. Baseline PET in rats and monkey showed specific retention in the PDE10A-rich striatum, and fast wash-out, with a good contrast to non-specific binding, in other brain regions. Pretreatment and chase experiments in rats with the selective PDE10A inhibitor MP-10 showed that tracer binding was specific and reversible. Absence of specific binding in PDE10A knock-out (KO) mice further confirmed PDE10A specificity. In vivo radiometabolite analysis using high performance liquid chromatography (HPLC) showed presence of polar radiometabolites in rat plasma and brain. In vivo imaging in rat and monkey further showed faster brain kinetics, and higher striatum-to-cerebellum ratios for [(18)F]JNJ42259152 compared to [(18)F]JNJ41510417. The arterial input function corrected for radiometabolites was determined in rats and basic kinetic modeling was established. For a 60-min acquisition time interval, striatal binding potential of the intact tracer referenced to the cerebellum showed good correlation with corresponding binding potential values of a Simplified Reference Tissue Model and referenced Logan Plot, the latter using a population averaged reference tissue-to-plasma clearance rate and offering the possibility to generate representative parametric binding potential images. In conclusion we can state that in vivo imaging in PDE10A KO mice, rats and monkey demonstrates that [(18)F]JNJ42259152 provides a PDE10A-specific signal in the striatum with good pharmacokinetic properties. Although presence of a polar radiometabolite in rat brain yielded a systematic but reproducible underestimation of the striatal BPND, a Logan reference tissue model approach using 60 min acquisition data is appropriate for quantification.

Equivalent dynamic human brain NK1-receptor occupancy following single-dose i.v. fosaprepitant vs. oral aprepitant as assessed by PET imaging.

The type 1 neurokinin receptor (NK1R) antagonist aprepitant and its i.v. prodrug fosaprepitant have been approved for prevention of acute and delayed nausea and vomiting associated with chemotherapy. This study evaluated the magnitude and duration of brain NK1R occupancy over a period of 5 days after single-dose i.v. infusion of 150-mg fosaprepitant and single-dose oral administration of 165-mg aprepitant, using serial [(18)F]MK-0999 positron emission tomography (PET) in 16 healthy subjects. Each subject underwent three scans. Brain NK1R occupancy rates after i.v. fosaprepitant at time to peak concentration (T(max); ~30 min), 24, 48, and 120 h after the dose were 100, 100, ≥97, and 41-75%, respectively. After aprepitant, NK1R occupancy rates at these time points (T(max) ~4 h) were ≥99, ≥99, ≥97, and 37-76%, respectively. Aprepitant plasma concentration profiles were comparable for the two dosage forms. The study illustrates the utility of PET imaging in determining central bioequivalence in a limited number of subjects.

Guidelines for heart transplantation.

Based on the changes in the field of heart transplantation and the treatment and prognosis of patients with heart failure, these updated guidelines were composed by a committee under the supervision of both the Netherlands Society of Cardiology and the Netherlands Association for Cardiothoracic surgery (NVVC and NVT).THE INDICATION FOR HEART TRANSPLANTATION IS DEFINED AS: 'End-stage heart disease not remediable by more conservative measures'.CONTRAINDICATIONS ARE: irreversible pulmonary hypertension/elevated pulmonary vascular resistance; active systemic infection; active malignancy or history of malignancy with probability of recurrence; inability to comply with complex medical regimen; severe peripheral or cerebrovascular disease and irreversible dysfunction of another organ, including diseases that may limit prognosis after heart transplantation.Considering the difficulties in defining end-stage heart failure, estimating prognosis in the individual patient and the continuing evolution of available therapies, the present criteria are broadly defined. The final acceptance is done by the transplant team which has extensive knowledge of the treatment of patients with advanced heart failure on the one hand and thorough experience with heart transplantation and mechanical circulatory support on the other hand. (Neth Heart J 2008;16:79-87.).

GATE: a simulation toolkit for PET and SPECT.

Monte Carlo simulation is an essential tool in emission tomography that can assist in the design of new medical imaging devices, the optimization of acquisition protocols and the development or assessment of image reconstruction algorithms and correction techniques. GATE, the Geant4 Application for Tomographic Emission, encapsulates the Geant4 libraries to achieve a modular, versatile, scripted simulation toolkit adapted to the field of nuclear medicine. In particular, GATE allows the description of time-dependent phenomena such as source or detector movement, and source decay kinetics. This feature makes it possible to simulate time curves under realistic acquisition conditions and to test dynamic reconstruction algorithms. This paper gives a detailed description of the design and development of GATE by the OpenGATE collaboration, whose continuing objective is to improve, document and validate GATE by simulating commercially available imaging systems for PET and SPECT. Large effort is also invested in the ability and the flexibility to model novel detection systems or systems still under design. A public release of GATE licensed under the GNU Lesser General Public License can be downloaded at http:/www-lphe.epfl.ch/GATE/. Two benchmarks developed for PET and SPECT to test the installation of GATE and to serve as a tutorial for the users are presented. Extensive validation of the GATE simulation platform has been started, comparing simulations and measurements on commercially available acquisition systems. References to those results are listed. The future prospects towards the gridification of GATE and its extension to other domains such as dosimetry are also discussed.

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.

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.

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.

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.