A new multi-modality imaging tool is under development in the framework of the INSERT (INtegrated SPECT/MRI for Enhanced Stratification in Radio-chemo Therapy) project, supported by the European ...Community. The final goal is to develop a custom SPECT apparatus, that can be used as an insert for commercially available MRI systems such as 3T MRI with 59cm bore diameter. INSERT is expected to offer more effective and earlier diagnosis with potentially better outcome in survival for the treatment of brain tumors, primarily glioma. Two SPECT prototypes will be developed, one dedicated to preclinical imaging, the second one dedicated to clinical imaging.
The basic building block of the SPECT detector ring is a small 5cm×5cm gamma camera, based on the well-established Anger architecture with a continuous scintillator readout by an array of silicon photodetectors. Silicon Drift Detectors (SDDs) and Silicon PhotoMultipliers (SiPM) are being considered as possible scintillator readout, considering that the detector choice plays a predominant role for the final performance of the system, such as energy and spatial resolution, as well as the useful field of view of the camera. Both solutions are therefore under study to evaluate their performances in terms of field of view (FOV), spatial and energy resolution. Preliminary simulations for both the preclinical and clinical systems have been carried out to evaluate resolution and sensitivity.
•We introduce INSERT, a new multi-modality SPECT/MRI instrument.•We propose two possible photodetectors (SDD, SiPM) for the scintillators readout.•We show possible results for INSERT, based on simulations.
In recent years there has been a trend towards designing single photon emission computed tomography (SPECT) systems specifically for application in cardiac imaging. There is now a wide range of ...systems designs ranging from compact dual detector system suited for either upright or supine patient positioning, specialized collimators or custom designed systems, some taking advantage of the compact design made possible with use of solid-state detectors. This paper provides an overview of these systems with discussion on merits and limitations.
In November, a workshop on dedicated brain imaging systems was held in conjunction with the IEEE NSS/MIC meeting in Atlanta, attracting over 100 attendees. The high level of interest prompted the ...production of this special issue which includes a wide range of topics including some that were presented at the workshop. In addition to submitted technical papers, this issue includes invited perspectives on the role of brain imaging in clinical practice with some emphasis on the system requirements to best meet these clinical needs.
Mutations in presenilin-1 (PSEN1) cause autosomal dominant Alzheimer's disease and mutations in MAPT cause the familial tauopathy Frontotemporal dementia linked to chromosome 17 (FTDP-17). However, ...there have been reports of mutations in PSEN1 and MAPT associated with cases of FTD with ubiquitin-positive tau-negative inclusion pathology. Here, we demonstrate that the MAPT variants are almost certainly rare benign polymorphisms as all of these cases harbour mutations in Progranulin (PGRN). Mutations in PGRN were recently shown to cause ubiquitin-positive FTDP-17.
Various biomarkers are available to support the diagnosis of neurodegenerative diseases in clinical and research settings. Among the molecular imaging biomarkers, amyloid-PET, which assesses brain ...amyloid deposition, and 18F-fluorodeoxyglucose (18F-FDG) PET, which assesses glucose metabolism, provide valuable and complementary information. However, uncertainty remains regarding the optimal timepoint, combination, and an order in which these PET biomarkers should be used in diagnostic evaluations because conclusive evidence is missing. Following an expert panel discussion, we reached an agreement on the specific use of the individual biomarkers, based on available evidence and clinical expertise. We propose a diagnostic algorithm with optimal timepoints for these PET biomarkers, also taking into account evidence from other biomarkers, for early and differential diagnosis of neurodegenerative diseases that can lead to dementia. We propose three main diagnostic pathways with distinct biomarker sequences, in which amyloid-PET and 18F-FDG-PET are placed at different positions in the order of diagnostic evaluations, depending on clinical presentation. We hope that this algorithm can support diagnostic decision making in specialist clinical settings with access to these biomarkers and might stimulate further research towards optimal diagnostic strategies.
A preclinical insert for small animal simultaneous SPECT and MR imaging, in particular for imaging mouse brains, is presented. It consists of ten static magnetic resonance imaging (MRI)-compatible ...gamma cameras based on tiles of silicon photomultipliers readout by a multichannel ASIC and coupled to 5 cm × 5 cm CsI(Tl) scintillators and to an MRI-compatible multipinhole collimator. Calibration and image reconstruction algorithm are illustrated. Mutual compatibility is demonstrated along with imaging performance that is comparable with other non-MR micro-SPECT systems: 0.9 mm tomographic spatial resolution across a transverse field of view of 15.6 mm, 12% energy resolution (at 140 keV), and 1105 cps/MBq sensitivity. Experimental results with phantoms (glass capillaries of 290 μm diameter and a mini Derenzo) are presented.
The HICAM Gamma Camera Fiorini, C.; Busca, P.; Peloso, R. ...
IEEE transactions on nuclear science,
06/2012, Letnik:
59, Številka:
3
Journal Article
Recenzirano
In this work we present a new compact and high-resolution Anger camera to be used in clinical and research environments where high overall spatial resolution and system compactness are required. The ...use of Silicon Drift Detectors (SDDs) as scintillator photodetectors, characterized by high quantum efficiency and low electronic noise, is the unique aspect of this camera. Two prototypes were developed during the project, with 5×5 SDDs and 10×10 SDDs (6 cm ×5 cm and 12 cm ×10 cm held-of-view, respectively). They provide a high intrinsic spatial resolution (<;1 mm), system spatial resolution of ~2 67 mm @ 4 cm and appropriate sensitivity. The prototypes have been used for assessment of performance and first measurements in both clinical trials and small animal imaging. We report on the results of imaging measurements carried out in the laboratory with the prototypes and on the most significant results obtained so far with this new camera employed in several applications.
We previously reported a kindred with three cases of dementia, in which the proband exhibited features typical of frontotemporal dementia and parkinsonism (FTDP). An arginine insertion at codon 352 ...(insR352) in the presenilin-1 (PSEN1) gene was identified in the proband, but analyses in plasma and CSF suggested a mechanism of neurodegeneration not directly related to amyloid pathophysiology. The proband was followed with yearly evaluations of functional, clinical, neuropsychologic, neuropsychiatric and radiologic status, which showed relatively linear change over the initial 4 years of assessment. Upon the proband's death at age 63, neuropathologic examination revealed frontotemporal lobar degeneration (FTLD) with ubiquitin-positive inclusions (FTLD-U). We recently identified several kindreds with familial FTDP associated with mutations in the progranulin (PGRN) gene, particularly in those cases with neuronal intranuclear inclusions. Our proband was indeed found to have such inclusions, and PGRN analysis in this proband revealed the G to A mutation in the exon 1 splice donor site (IVS1+1G→A) which is predicted to destroy the 5′-splice site of exon 1 and remove the start methionine codon and hence completely block any PGRN protein from being generated. These findings suggest that the insR352 PSEN1 is not pathogenic, and the IVS1+1G→A mutation in PGRN causes FTDP associated with FTLD-U pathology and represents a new class of neurodegenerative disease—the ‘hypoprogranulinopathies’.
Simultaneous PET–MR acquisition reduces the possibility of registration mismatch between the two modalities. This facilitates the application of techniques, either during reconstruction or ...post-reconstruction, that aim to improve the PET resolution by utilising structural information provided by MR. However, in order to validate such methods for brain PET–MR studies it is desirable to evaluate the performance using data where the ground truth is known. In this work, we present a framework for the production of datasets where simulations of both the PET and MR, based on real data, are generated such that reconstruction and post-reconstruction approaches can be fairly compared.
•A framework for simulating realistic brain PET–MR images is proposed.•The imaging data created is formed from real acquisitions.•Partial volume correction techniques can be fairly compared using this framework.
We present three novel multi-slit-slat (MSS) system designs which allow for the acquisition of data with variable multiplexing in order to optimize the use of a high intrinsic resolution detector for ...clinical brain SPECT. In this paper we first study the relationship between the geometric parameters of a MSS collimator system and the resulting resolution and sensitivity for an on-axis point at the centre of the field-of-view (FOV), assuming a continuous cylindrical detector model. The model predicts that for optimal system sensitivity and resolution, the ratio of the detector radius to slit collimator radius should be 1.3-1.5, as any further increase in this ratio results in significant deterioration in both system resolution and sensitivity. The analytical results were used to fix the geometric parameters for the three novel MSS system designs. Comparison of the three designs, asymmetric rotating collimator (ARC), asymmetric rotating detector (ARD) and symmetric rotating collimator (SRC) with variable slit spacing, suggests that the SRC system performs better in terms of the system sensitivity (5.1 x 10(-4)) for the same average resolution (6.0 mm) in comparison to designs based on an ARC (3.7 x 10(-4)) and ARD (4.2 x 10(-4)).
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