A linear wavelet filter for parametric imaging with dynamic pet

Turkheimer, Federico; Aston, John A. D.; Bánati, Richard B.; Riddell, Cyril; Cunningham, Vincent J.

doi:10.1109/tmi.2003.809597

Cited by 64 publications

(44 citation statements)

References 39 publications

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“…The parameters of filter kernel (length of the wavelet filters) and depth-of-decomposition (optimal number of iterations) have previously been optimized to 16 and 3, respectively [25]. Quantification was performed with Logan's graphical analysis using multi-linear regression to fit the linear part of the curve of the coefficients from the dynamic wavelet transform [26]. The parametric wavelet transform describing the distribution of the total distribution volume (V T ) was then transformed to a three-dimensional (3D) parametric map of V T in normal space.…”

Section: Parametric Imagesmentioning

confidence: 99%

Test–retest reproducibility of [11C]PBR28 binding to TSPO in healthy control subjects

Collste

Forsberg

Varrone

et al. 2015

Eur J Nucl Med Mol Imaging

109

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Here, we examined reproducibility of [ 11 C]PBR28 binding in healthy subjects as quantified on a regional and voxel-by-voxel basis. In addition, a preliminary analysis of diurnal changes in TSPO availability was performed. MethodsTwelve subjects were examined with HRRT PET and [ 11 C]PBR28, six in the morning and afternoon on the same day, and six in the morning of two separate days. Regional Volume of distribution (V T ) values were derived using a region-of-interest based two-tissue compartmental analysis (2TCM), as well as a parametric approach. Metabolite-corrected arterial plasma was used as input function. ResultsFor the whole sample, the mean absolute variability of V T in gray matter (GM) was 18.3 ± 12.7 %. Intraclass Correlation Coefficient values in GM regions ranged from 0.90 to 0.94. Reducing the time of analysis from 91 to 63 minutes yielded a variability of 16.9 ± 14.9%. There was a strong correlation between the parametric and 2TCM-derived GM values (r=0.99). A significant increase in GM V T was observed between morning and afternoon examinations when using secondary methods of quantification (p=0.028). For the subjects examined at the same time of the day, the absolute variability was 15.9 ± 12.2 % for the 91 minute 2TCM data. [15,16], the study was designed so that six subjects were examined in the morning and afternoon on the same day, and six subjects at the same time point on two different days. Conclusions Methods SubjectsThe study was conducted at the Karolinska University Hospital, Solna, Sweden and was approved by the regional Ethics Committee in Stockholm and the Radiation Safety Committee at the Karolinska University Hospital, Stockholm.Subjects were recruited by advertisement and provided written informed consent. They were healthy according to medical history, clinical examination and routine laboratory tests in blood and urine. All subjects were assessed by a senior psychiatrist (K.C.), using the Mini International Neuropsychiatric Interview (MINI) for psychiatric diagnoses. None of the subjects had previously been exposed to psychopharmacological medication. Furthermore, a negative illegal drug screening test was ascertained in all subjects, prior to PET examination. None of the subjects were on any medication at the time of the study. No brain abnormality was detected on magnetic resonance imaging (MRI), as evaluated by a neuroradiologist at the MR-centre, Karolinska University Hospital, Solna.As demonstrated both in vitro and in vivo, [ 11 C]PBR28 binding is influenced by an identified single point mutation in the TSPO gene [8,17]. At screening, a blood sample was collected and genotyping was performed according to the description below. In total, 15 subjects were recruited. Of these, one was a low affinity binder (LAB) and was therefore excluded from the analysis. Two additional subjects were excluded due to technical issues with the PET measurements. The remaining twelve subjects were six men and six women, with a mean age of 23.9 SD ± 3.1 years. Six were high affinity binders ...

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Section: Parametric Imagesmentioning

confidence: 99%

Test–retest reproducibility of [11C]PBR28 binding to TSPO in healthy control subjects

Collste

Forsberg

Varrone

et al. 2015

Eur J Nucl Med Mol Imaging

109

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“…PET study was performed in three-dimensional acquisition mode as previously reported [19]. A 6 mCi bolus of [ 11 C](R)-PK11195 was injected intravenously into the patients 30 sec after the acquisition scan started.…”

Section: Pet Imaging Acquisition and Analysismentioning

confidence: 99%

The lack of expression of the peripheral benzodiazepine receptor characterises microglial response in anaplastic astrocytomas

et al. 2007

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The peripheral benzodiazepine receptor (PBR) is a 18 kDa molecule mainly involved in cholesterol transport through the mitochondrial membrane. In microglia, PBR is expressed from the earliest stages of activation and appears to exert a pro-inflammatory function. This molecule is commonly up-regulated in inflammatory, degenerative, infective and ischaemic lesions of the central nervous system but it has never been reported in glioma-infiltrating microglia. We examined two anaplastic astrocytomas showing minimal contrast-enhancement and therefore little damage of the blood brain barrier to minimise the presence of blood borne macrophages within tumour tissue. The two lesions were studied in vivo using positron emission tomography (PET) with the specific PBR ligand [ 11 C](R)-PK11195 and the corresponding tumour tissue was investigated with an anti-PBR antibody. Glioma-infiltrating microglia were characterised for molecules involved in antigen presentation and cytotoxic activity. As comparison, PBR was investigated in three brains with multiple sclerosis (MS) and three with Parkinson's disease (PD). The expression profile of four anaplastic astrocytomas was also exploited and results were compared to the profile of eleven samples of normal temporal lobe and nine cases of PD. PET studies showed that [ 11 C](R)-PK11195 binding was markedly lower in tumours than in the contralateral grey matter. Pathological investigation revealed that glioma-infiltrating microglia failed to express PBR and cytotoxic molecules although some cells still expressed antigen presenting molecules. PBR and cytotoxic molecules were highly represented in MS and PD. Evaluation of microarray datasets confirmed these differences. Our results demonstrated PBR suppression in glioma-infiltrating microglia and suggested that PBR may have a relevant role in modulating the anti-tumour inflammatory response in astrocytic tumours.

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“…[19][20][21][22][23][24][25] As HYPR-LR uses temporally integrated data to reduce noise, comparing it to denoising methods that likewise utilize the time domain, such 4D reconstructions, will be particularly important. Iterative reconstructions, wavelet denoising, and HYPR-LR have all demonstrated an ability to substantially reduce noise, but each also has drawbacks.…”

Section: Discussionmentioning

confidence: 99%

Improved kinetic analysis of dynamic PET data with optimized HYPR‐LR

et al. 2012

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Purpose: Highly constrained backprojection-local reconstruction (HYPR-LR) has made a dramatic impact on magnetic resonance angiography (MRA) and shows promise for positron emission tomography (PET) because of the improvements in the signal-to-noise ratio (SNR) it provides dynamic images. For PET in particular, HYPR-LR could improve kinetic analysis methods that are sensitive to noise. In this work, the authors closely examine the performance of HYPR-LR in the context of kinetic analysis, they develop an implementation of the algorithm that can be tailored to specific PET imaging tasks to minimize bias and maximize improvement in variance, and they provide a framework for validating the use of HYPR-LR processing for a particular imaging task. Methods: HYPR-LR can introduce errors into non sparse PET studies that might bias kinetic parameter estimates. An implementation of HYPR-LR is proposed that uses multiple temporally summed composite images that are formed based on the kinetics of the tracer being studied (HYPR-LR-MC). The effects of HYPR-LR-MC and of HYPR-LR using a full composite formed with all the frames in the study (HYPR-LR-FC) on the kinetic analysis of Pittsburgh compound-B ([11C]-PIB) are studied. HYPR-LR processing is compared to spatial smoothing. HYPR-LR processing was evaluated using both simulated and human studies. Nondisplaceable binding potential (BP ND ) parametric images were generated from fifty noise realizations of the same numerical phantom and eight [ 11 C]-PIB positive human scans before and after HYPR-LR processing or smoothing using the reference region Logan graphical method and receptor parametric mapping (RPM2). The bias and coefficient of variation in the frontal and parietal cortex in the simulated parametric images were calculated to evaluate the absolute performance of HYPR-LR processing. Bias in the human data was evaluated by comparing parametric image BP ND values averaged over large regions of interest (ROIs) to Logan estimates of the BP ND from TACs averaged over the same ROIs. Variance was assessed qualitatively in the parametric images and semiquantitatively by studying the correlation between voxel BP ND estimates from Logan analysis and RPM2. Results: Both the simulated and human data show that HYPR-LR-FC overestimates BP ND values in regions of high [ 11

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A linear wavelet filter for parametric imaging with dynamic pet

Cited by 64 publications

References 39 publications

Test–retest reproducibility of [11C]PBR28 binding to TSPO in healthy control subjects

Test–retest reproducibility of [11C]PBR28 binding to TSPO in healthy control subjects

The lack of expression of the peripheral benzodiazepine receptor characterises microglial response in anaplastic astrocytomas

Improved kinetic analysis of dynamic PET data with optimized HYPR‐LR

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