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Non-isotropic noise correlation in PET data reconstructed by FBP but not by OSEM demonstrated using auto-correlation function
Pasha Razifar, Mark Lubberink, Harald Schneider, Bengt L？ngstr？m, Ewert Bengtsson, Mats Bergstr？m
BMC Medical Imaging , 2005, DOI: 10.1186/1471-2342-5-3
Abstract: In this paper we explored the pattern of noise correlation in experimentally generated PET images, with emphasis on the angular dependence of correlation, using the autocorrelation function (ACF). Experimental PET data were acquired in 2D and 3D acquisition mode and reconstructed by analytical filtered back projection (FBP) and iterative ordered subsets expectation maximisation (OSEM) methods. The 3D data was rebinned to a 2D dataset using FOurier REbinning (FORE) followed by 2D reconstruction using either FBP or OSEM. In synthetic images we compared the ACF results with those from covariance matrix. The results were illustrated as 1D profiles and also visualized as 2D ACF images.We found that the autocorrelation images from PET data obtained after FBP were not fully rotationally symmetric or isotropic if the object deviated from a uniform cylindrical radioactivity distribution. In contrast, similar autocorrelation images obtained after OSEM reconstruction were isotropic even when the phantom was not circular. Simulations indicated that the noise autocorrelation is non-isotropic in images created by FBP when the level of noise in projections is angularly variable. Comparison between 1D cross profiles on autocorrelation images obtained by FBP reconstruction and covariance matrices produced almost identical results in a simulation study.With asymmetric radioactivity distribution in PET, reconstruction using FBP, in contrast to OSEM, generates images in which the noise correlation is non-isotropic when the noise magnitude is angular dependent, such as in objects with asymmetric radioactivity distribution. In this respect, iterative reconstruction is superior since it creates isotropic noise correlations in the images.Positron Emission Tomography (PET) is a technique based on tracing of molecules labelled with positron-emitting radionuclides to image metabolism, physiology, and functionality in vivo in organs and tissues. PET has become an important, non-invasive techni
Optimal timing of tau pathology imaging and automatic extraction of a reference region using dynamic [18F]THK5317 PET
Agneta Nordberg,Anders Wall,Antoine Leuzy,Gunnar Antoni,Jonas Eriksson,Konstantinos Chiotis,Mark Lubberink,My Jonasson
- , 2019, DOI: 10.1016/j.nicl.2019.101681
Abstract: [18F]THK5317 is a PET tracer for in-vivo imaging of tau associated with Alzheimer's disease (AD). This work aimed to evaluate optimal timing for standardized uptake value ratio (SUVR) measures with [18F]THK5317 and automated generation of SUVR-1 and relative cerebral blood flow (R1) parametric images. Nine AD patients and nine controls underwent 90？min [18F]THK5317 scans. SUVR-1 was calculated at transient equilibrium (TE) and for seven different 20？min intervals and compared with distribution volume ratio (DVR; reference Logan). Cerebellar grey matter (MRI) was used as reference region. A supervised cluster analysis (SVCA) method was implemented to automatically generate a reference region, directly from the dynamic PET volume without the need of a structural MRI scan, for computation of SUVR-1 and R1 images for a scan duration matching the optimal timing. TE was reached first in putamen, frontal- and parietal cortex at 22？±？4？min for AD patients and in putamen at 20？±？0？min in controls. Over all regions and subjects, SUVR20–40-1 correlated best with DVR-1, R2？=？0.97. High correlation was found between values generated using MRI- and SVCA-based reference (R2？=？0.93 for SUVR20–40-1; R2？=？0.94 for R1). SUVR20–40 allows for accurate semi-quantitative assessment of tau pathology and SVCA may be used to obtain a reference region for calculation of both SUVR-1 and R1 with 40？min scan duration
Lessons on Tumour Response: Imaging during Therapy with 177Lu-DOTA-octreotate. A Case Report on a Patient with a Large Volume of Poorly Differentiated Neuroendocrine Carcinoma
Ulrike Garske, Mattias Sandstr？m, Silvia Johansson, Dan Granberg, Hans Lundqvist, Mark Lubberink, Anders Sundin, Barbro Eriksson
Theranostics , 2012,
Abstract: Favourable outcomes of peptide receptor radiotherapy (PRRT) of neuroendocrine tumours have been reported during the last years. Still, there are uncertainties on the radionuclides to be used, the treatment planning, and the indication in patients with a high proliferation rate. This case report describes a patient with a high tumour burden of poorly differentiated neuroendocrine carcinoma of unknown primary with a proliferation rate in liver metastases up to 50%, undergoing fractionated treatment with 7 cycles of 177Lu-DOTA-octreotate (7.4 GBq each) after disease progression on two different chemotherapy regiments. Based on initial staging scintigraphy, somatostatin receptor expression was very high. Longitudinal dosimetry studies during therapy indicated ongoing increases in tumour-to-organ ratios that coincided with an objective response. We conclude that fractionated therapy with 177Lu-DOTA-octreotate should be considered a treatment option also for those patients with large tumours, high proliferation, and high receptor expression.
Validation of true low-dose 18F-FDG PET of the brain
David F？llmar,Elna-Marie Larsson,Jens S？rensen,Johan Lilja,Lena Kilander,Mark Lubberink,Torsten Danfors
- , 2016,
Abstract: The dosage of 18F-FDG must be sufficient to ensure adequate PET image quality. For younger patients and research controls, the lowest possible radiation dose should be used. The purpose of this study was to find a protocol for FDG-PET of the brain with reduced radiation dose and preserved quantitative characteristics. Eight patients with neurodegenerative disorders and nine controls (n=17) underwent FDG-PET/CT twice on separate occasions, first with normal-dose (3 MBq/kg), and second with low-dose (0.75 MBq/kg, 25% of the original). Five additional controls (total n=22) underwent FDG-PET twice, using normal-dose and ultra-low-dose (0.3 MBq/kg, 10% of original). All subjects underwent MRI. Ten-minute summation images were spatially normalized and intensity normalized. Regional standard uptake value ratios (SUV-r) were calculated using an automated atlas. SUV-r values from the normal- and low-dose images were compared pairwise. No clinically significant bias was found in any of the three groups. The mean absolute difference in regional SUV-r values was 0.015 (1.32%) in controls and 0.019 (1.67%) in patients. The ultra-low-dose protocol produced a slightly higher mean difference of 0.023 (2.10%). The main conclusion is that 0.75 MBq/kg (56 MBq for a 75-kg subject) is a sufficient FDG dose for evaluating regional SUV-ratios in brain PET scans in adults with or without neurodegenerative disease, resulting in a reduction of total PET/CT effective dose from 4.54 to 1.15 mSv. The ultra-low-dose (0.5 mSv) could be useful in research studies requiring serial PET in healthy controls or children
Z-score maps from low-dose 18F-FDG PET of the brain in neurodegenerative dementia
David F？llmar,Elna-Marie Larsson,Jens S？rensen,Johan Lilja,Lena Kilander,Mark Lubberink,Torsten Danfors,Victor Iyer
- , 2018,
Abstract:
Reproducibility of quantitative (R)-[11C]verapamil studies
Dani？lle ME van Assema, Mark Lubberink, Ronald Boellaard, Robert C Schuit, Albert D Windhorst, Philip Scheltens, Bart NM van Berckel, Adriaan A Lammertsma
EJNMMI Research , 2012, DOI: 10.1186/2191-219x-2-1
Abstract: Dynamic (R)-[11C]verapamil scans with arterial sampling were performed twice on the same day in 13 healthy controls. Data were reconstructed using both filtered back projection [FBP] and partial volume corrected ordered subset expectation maximization [PVC OSEM]. All data were analysed using single-tissue and two-tissue compartment models. Global and regional test-retest variability was determined for various outcome measures.Analysis using the Akaike information criterion showed that a constrained two-tissue compartment model provided the best fits to the data. Global test-retest variability of the volume of distribution was comparable for single-tissue (6%) and constrained two-tissue (9%) compartment models. Using a single-tissue compartment model covering the first 10 min of data yielded acceptable global test-retest variability (9%) for the outcome measure K1. Test-retest variability of binding potential derived from the constrained two-tissue compartment model was less robust, but still acceptable (22%). Test-retest variability was comparable for PVC OSEM and FBP reconstructed data.The model of choice for analysing (R)-[11C]verapamil data is a constrained two-tissue compartment model.P-glycoprotein [Pgp] is considered to be the most important efflux transporter at the human blood-brain barrier [BBB] because of its high expression and its ability to transport a wide range of substrates from the brain into the circulation and cerebrospinal fluid. Pgp plays an important role in protecting the brain from endogenous and exogenous toxic substances by removing them before they reach the parenchyma [1-5]. It has been hypothesised that decreased Pgp function and/or expression at the BBB are involved in several neurological disorders, such as Creutzfeldt-Jakob disease, Parkinson's disease and Alzheimer's disease [AD] [6-9]. On the other hand, increased Pgp function may be involved in drug-resistant epilepsy [10].Over the past years, several positron emission tomography [
Development of a clinically feasible [11C]PE2I PET method for differential diagnosis of parkinsonism using reduced scan duration and automated reference region extraction
Andreas Frick,Dag Nyholm,H？kan Askmark,Jens S？rensen,Jonas Engman,Lieuwe Appel,Mark Lubberink,My Jonasson,Tomas Furmark,Torsten Danfors
- , 2017,
Abstract: [11C]PE2I is a highly selective dopamine transporter PET ligand. Parametric images based on dynamic [11C]PE2I scans, showing dopamine transporter availability (BPND) and relative cerebral blood flow (R1), can be used in differential diagnosis of parkinsonism. This work aimed to investigate a shortened scan duration and automated generation of parametric images which are two prerequisites for routine clinical application. Twelve subjects with parkinsonism and seventeen healthy controls underwent 80 min dynamic [11C]PE2I PET scans. BPND and R1 images were generated using cerebellum reference region defined on a co-registered MRI, as well as a supervised cluster analysis (SVCA)-based reference. Initial 20, 30 and 40 min of the scans were extracted and images of standardized uptake value ratio (SUVR) and R1 were computed using MRI- and SVCA-based reference. Correlation was high between striatal 80 min MRI-based BPND and 40 min SVCA-based SUVR-1 (R2=0.95). High correlation was also found between R1 values in striatal and limbic regions (R2≥0.91) whereas correlation was moderate for cortical regions (R2=0.71). The results indicate that dynamic [11C]PE2I scans can be restricted to 40 min and that SVCA can be used for automatic extraction of a reference region. These outcomes will support routine applications of [11C]PE2I PET in clinical settings
Measuring HER2-Receptor Expression In Metastatic Breast Cancer Using [68Ga]ABY-025 Affibody PET/CT
Anders Wennborg,Anna Orlova,Dan Sandberg,Helena Olofsson,Henrik Lindman,Irina Velikyan,Jens S？rensen,Joachim Feldwisch,J？rgen Carlsson,Mark Lubberink,Mattias Sandstr？m,Vladimir Tolmachev
- , 2016, DOI: 10.7150/thno.13502
Abstract:
Cerebral serotonin transporter measurements with [11C]DASB: A review on acquisition and preprocessing across 21 PET centres
Claus Svarer,Eugenii A Rabiner,Federico Turkheimer,Gitte M Knudsen,Ling Feng,Marios Politis,Mark Lubberink,Mark Slifstein,Martin N？rgaard,Masanori Ichise,Melanie Ganz,Peter S Talbot,Ramin V Parsey,Rupert Lanzenberger,Stephen C Strother,Tetsuya Suhara,Vesna Sossi
- , 2019, DOI: 10.1177/0271678X18770107
Abstract: Positron Emission Tomography (PET) imaging has become a prominent tool to capture the spatiotemporal distribution of neurotransmitters and receptors in the brain. The outcome of a PET study can, however, potentially be obscured by suboptimal and/or inconsistent choices made in complex processing pipelines required to reach a quantitative estimate of radioligand binding. Variations in subject selection, experimental design, data acquisition, preprocessing, and statistical analysis may lead to different outcomes and neurobiological interpretations. We here review the approaches used in 105 original research articles published by 21 different PET centres, using the tracer [11C]DASB for quantification of cerebral serotonin transporter binding, as an exemplary case. We highlight and quantify the impact of the remarkable variety of ways in which researchers are currently conducting their studies, while implicitly expecting generalizable results across research groups. Our review provides evidence that the foundation for a given choice of a preprocessing pipeline seems to be an overlooked aspect in modern PET neuroscience. Furthermore, we believe that a thorough testing of pipeline performance is necessary to produce reproducible research outcomes, avoiding biased results and allowing for better understanding of human brain function
Blood–brain barrier P-glycoprotein function in healthy subjects and Alzheimer's disease patients: effect of polymorphisms in the ABCB1 gene
Dani？lle ME van Assema, Mark Lubberink, Patrizia Rizzu, John C van Swieten, Robert C Schuit, Jonas Eriksson, Philip Scheltens, Matthias Koepp, Adriaan A Lammertsma, Bart NM van Berckel
EJNMMI Research , 2012, DOI: 10.1186/2191-219x-2-57
Abstract: Thirty-two healthy subjects and seventeen patients with Alzheimer's disease underwent 60-min dynamic (R)-[11C]verapamil PET scans. The binding potential of (R)-[11C]verapamil was assessed using a previously validated constrained two-tissue plasma input compartment model and used as outcome measure. DNA was isolated from frozen blood samples and C1236T, G2677T/A and C3435T single-nucleotide polymorphisms were amplified by polymerase chain reaction.In healthy controls, binding potential did not differ between subjects without and with one or more T present in C1236T, G2677T and C3435T. In contrast, patients with Alzheimer's disease with one or more T in C1236T, G2677T and C3435T had significantly higher binding potential values than patients without a T. In addition, there was a relationship between binding potential and T dose in C1236T and G2677T.In Alzheimer's disease patients, C1236T, G2677T/A and C3435T single-nucleotide polymorphisms may be related to changes in P-glycoprotein function at the blood–brain barrier. As such, genetic variations in ABCB1 might contribute to the progression of amyloid-beta deposition in the brain.P-glycoprotein (Pgp) is a 170 kDa membrane-bound efflux transporter located in several organs throughout the body with an excretory and/or barrier function, such as the liver, kidneys, intestine, placenta, testes and the blood–brain barrier (BBB) [1]. At the BBB, Pgp is highly expressed and has an important function in the transport of a wide variety of endogenous and exogenous substances out of the brain into the bloodstream [2]. Pgp has been shown to play a role in amyloid-beta clearance from the brain and, as such, has been hypothesized to be involved in the pathogenesis of Alzheimer's disease (AD) [3]. Recently, BBB Pgp dysfunction in AD patients was shown using the Pgp substrate tracer (R)-11C]verapamil and positron emission tomography (PET) [4].Pgp is encoded in the ABCB1 gene (formerly known as the multidrug resistance (MDR1) gene), wh
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