1
|
Kanellopoulos P, Nock BA, Rouchota M, Loudos G, Krenning EP, Maina T. Side-Chain Modified [ 99mTc]Tc-DT1 Mimics: A Comparative Study in NTS 1R-Positive Models. Int J Mol Sci 2023; 24:15541. [PMID: 37958525 PMCID: PMC10647616 DOI: 10.3390/ijms242115541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Revised: 10/21/2023] [Accepted: 10/23/2023] [Indexed: 11/15/2023] Open
Abstract
Radiolabeled neurotensin analogs have been developed as candidates for theranostic use against neurotensin subtype 1 receptor (NTS1R)-expressing cancer. However, their fast degradation by two major peptidases, neprilysin (NEP) and angiotensin-converting enzyme (ACE), has hitherto limited clinical success. We have recently shown that palmitoylation at the ε-amine of Lys7 in [99mTc]Tc-[Lys7]DT1 (DT1, N4-Gly-Arg-Arg-Pro-Tyr-Ile-Leu-OH, N4 = 6-(carboxy)-1,4,8,11-tetraazaundecane) led to the fully stabilized [99mTc]Tc-DT9 analog, displaying high uptake in human pancreatic cancer AsPC-1 xenografts but unfavorable pharmacokinetics in mice. Aiming to improve the in vivo stability of [99mTc]Tc-DT1 without compromising pharmacokinetics, we now introduce three new [99mTc]Tc-DT1 mimics, carrying different pendant groups at the ε-amine of Lys7: MPBA (4-(4-methylphenyl)butyric acid)-[99mTc]Tc-DT10; MPBA via a PEG4-linker-[99mTc]Tc-DT11; or a hydrophilic PEG6 chain-[99mTc]Tc-DT12. The impact of these modifications on receptor affinity and internalization was studied in NTS1R-positive cells. The effects on stability and AsPC-1 tumor uptake were assessed in mice without or during NEP/ACE inhibition. Unlike [99mTc]Tc-DT10, the longer-chain modified [99mTc]Tc-DT11 and [99mTc]Tc-DT12 were significantly stabilized in vivo, resulting in markedly improved tumor uptake compared to [99mTc]Tc-DT1. [99mTc]Tc-DT11 was found to achieve the highest AsPC-1 tumor values and good pharmacokinetics, either without or during NEP inhibition, qualifying for further validation in patients with NTS1R-positive tumors using SPECT/CT.
Collapse
Affiliation(s)
| | - Berthold A. Nock
- Molecular Radiopharmacy, INRaSTES, NCSR “Demokritos”, 15341 Athens, Greece; (P.K.); (B.A.N.)
| | - Maritina Rouchota
- BIOEMTECH, Lefkippos Attica Technology Park NCSR “Demokritos”, 15310 Athens, Greece; (M.R.); (G.L.)
| | - George Loudos
- BIOEMTECH, Lefkippos Attica Technology Park NCSR “Demokritos”, 15310 Athens, Greece; (M.R.); (G.L.)
| | - Eric P. Krenning
- Cyclotron Rotterdam BV, Erasmus MC, 3015 CE Rotterdam, The Netherlands;
| | - Theodosia Maina
- Molecular Radiopharmacy, INRaSTES, NCSR “Demokritos”, 15341 Athens, Greece; (P.K.); (B.A.N.)
| |
Collapse
|
2
|
Strugari ME, DeBay DR, Beyea SD, Brewer KD. NEMA NU 1-2018 performance characterization and Monte Carlo model validation of the Cubresa Spark SiPM-based preclinical SPECT scanner. EJNMMI Phys 2023; 10:35. [PMID: 37261574 DOI: 10.1186/s40658-023-00555-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 05/15/2023] [Indexed: 06/02/2023] Open
Abstract
BACKGROUND The Cubresa Spark is a novel benchtop silicon-photomultiplier (SiPM)-based preclinical SPECT system. SiPMs in SPECT significantly improve resolution and reduce detector size compared to preclinical cameras with photomultiplier tubes requiring highly magnifying collimators. The NEMA NU 1 Standard for Performance Measurements of Gamma Cameras provides methods that can be readily applied or extended to characterize preclinical cameras with minor modifications. The primary objective of this study is to characterize the Spark according to the NEMA NU 1-2018 standard to gain insight into its nuclear medicine imaging capabilities. The secondary objective is to validate a GATE Monte Carlo simulation model of the Spark for use in preclinical SPECT studies. METHODS NEMA NU 1-2018 guidelines were applied to characterize the Spark's intrinsic, system, and tomographic performance with single- and multi-pinhole collimators. Phantoms were fabricated according to NEMA specifications with deviations involving high-resolution modifications. GATE was utilized to model the detector head with the single-pinhole collimator, and NEMA measurements were employed to tune and validate the model. Single-pinhole and multi-pinhole SPECT data were reconstructed with the Software for Tomographic Image Reconstruction and HiSPECT, respectively. RESULTS The limiting intrinsic resolution was measured as 0.85 mm owing to a high-resolution SiPM array combined with a 3 mm-thick scintillation crystal. The average limiting tomographic resolution was 1.37 mm and 1.19 mm for the single- and multi-pinhole collimators, respectively, which have magnification factors near unity at the center of rotation. The maximum observed count rate was 15,400 cps, and planar sensitivities of 34 cps/MBq and 150 cps/MBq were measured at the center of rotation for the single- and multi-pinhole collimators, respectively. All simulated tests agreed well with measurement, where the most considerable deviations were below 7%. CONCLUSIONS NEMA NU 1-2018 standards determined that a SiPM detector mitigates the need for highly magnifying pinhole collimators while preserving detailed information in projection images. Measured and simulated NEMA results were highly comparable with differences on the order of a few percent, confirming simulation accuracy and validating the GATE model. Of the collimators initially provided with the Spark, the multi-pinhole collimator offers high resolution and sensitivity for organ-specific imaging of small animals, and the single-pinhole collimator enables high-resolution whole-body imaging of small animals.
Collapse
Affiliation(s)
- Matthew E Strugari
- Biomedical Translational Imaging Centre, Halifax, NS, Canada.
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS, Canada.
| | - Drew R DeBay
- Biomedical Translational Imaging Centre, Halifax, NS, Canada
- Cubresa Inc., Winnipeg, MB, Canada
| | - Steven D Beyea
- Biomedical Translational Imaging Centre, Halifax, NS, Canada
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS, Canada
- Department of Diagnostic Radiology, Dalhousie University, Halifax, NS, Canada
- School of Biomedical Engineering, Dalhousie University, Halifax, NS, Canada
| | - Kimberly D Brewer
- Biomedical Translational Imaging Centre, Halifax, NS, Canada
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS, Canada
- Department of Diagnostic Radiology, Dalhousie University, Halifax, NS, Canada
- School of Biomedical Engineering, Dalhousie University, Halifax, NS, Canada
- Department of Microbiology and Immunology, Dalhousie University, Halifax, NS, Canada
| |
Collapse
|
3
|
Meng LJ, Clinthorne NH. Small-Animal SPECT, SPECT/CT, and SPECT/MRI. Mol Imaging 2021. [DOI: 10.1016/b978-0-12-816386-3.00007-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
|
4
|
Ozsahin I, Chen L, Könik A, King MA, Beekman FJ, Mok GSP. The clinical utilities of multi-pinhole single photon emission computed tomography. Quant Imaging Med Surg 2020; 10:2006-2029. [PMID: 33014732 PMCID: PMC7495312 DOI: 10.21037/qims-19-1036] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 07/30/2020] [Indexed: 11/06/2022]
Abstract
Single photon emission computed tomography (SPECT) is an important imaging modality for various applications in nuclear medicine. The use of multi-pinhole (MPH) collimators can provide superior resolution-sensitivity trade-off when imaging small field-of-view compared to conventional parallel-hole and fan-beam collimators. Besides the very successful application in small animal imaging, there has been a resurgence of the use of MPH collimators for clinical cardiac and brain studies, as well as other small field-of-view applications. This article reviews the basic principles of MPH collimators and introduces currently available and proposed clinical MPH SPECT systems.
Collapse
Affiliation(s)
- Ilker Ozsahin
- Biomedical Imaging Laboratory, Department of Electrical and Computer Engineering, Faculty of Science and Technology, University of Macau, Macau, China
- Department of Biomedical Engineering, Faculty of Engineering, Near East University, Nicosia/TRNC, Mersin-10, Turkey
- DESAM Institute, Near East University, Nicosia/TRNC, Mersin-10, Turkey
| | - Ling Chen
- Biomedical Imaging Laboratory, Department of Electrical and Computer Engineering, Faculty of Science and Technology, University of Macau, Macau, China
| | - Arda Könik
- Department of Imaging, Dana Farber Cancer Institute, Boston, MA, USA
| | - Michael A. King
- Department of Radiology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Freek J. Beekman
- Section of Biomedical Imaging, Department of Radiation Science and Technology, Delft University of Technology, Mekelweg 15, 2629 JB Delft, The Netherlands
- MILabs B.V, Heidelberglaan 100, 3584 CX, Utrecht, The Netherlands
- Department of Translational Neuroscience, Brain Center Rudolf Magnus, University Medical Center Utrecht, The Netherlands
| | - Greta S. P. Mok
- Biomedical Imaging Laboratory, Department of Electrical and Computer Engineering, Faculty of Science and Technology, University of Macau, Macau, China
- Center for Cognitive and Brain Sciences, Institute of Collaborative Innovation, University of Macau, Macau, China
| |
Collapse
|
5
|
Tseng HW, Vedantham S, Cho SH, Karellas A. Joint Optimization of Collimator and Reconstruction Parameters in X-Ray Fluorescence Computed Tomography Using Analytical Point Spread Function and Model Observer. IEEE Trans Biomed Eng 2020; 67:2443-2452. [PMID: 31899411 PMCID: PMC7326652 DOI: 10.1109/tbme.2019.2963040] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
OBJECTIVE To jointly optimize collimator design and image reconstruction algorithm in X-ray Fluorescence Computed Tomography (XFCT) for imaging low concentrations of high atomic number (Z) elements in small animal models. METHODS Single pinhole (SPH) collimator and three types of multi-pinhole (MPH) collimators were evaluated. MPH collimators with 5, 7, and 9 pinholes using lead, stainless steel and brass were considered. A digital cylindrical phantom (0.5 mm3 voxels) of 25 mm diameter and 25 mm height with a central 5 mm diameter and 12.5 mm height cylindrical insert containing gold nanoparticles (2:1 insert: background concentration) was modeled. A 125 kVp, 2 mm Sn filtered x-ray spectrum (0.5 cGy/projection) for gold K-shell XFCT was considered. System matrices were implemented using analytical point spread functions (PSF) for each pinhole collimator. Poisson noise was added to the projection data (16 equiangular views) before image reconstruction using Maximum-Likelihood Expectation-Maximization (ML-EM) algorithm. Signal-present and signal-absent images were generated for the detection task performed by a channelized Hotelling observer (CHO) with 10 Dense Difference-of-Gaussian channels. The area under the curve (AUC) in receiver operating characteristic was used as the image quality metric. RESULTS A stainless steel focusing type MPH with 7 pinholes and 20 iterations of ML-EM provided the highest AUC. CONCLUSION MPH collimators outperformed SPH collimators for XFCT and consistently high AUCs were observed with focusing type MPH designs with 7 pinholes. SIGNIFICANCE The combinations of collimator design and image reconstruction parameters that maximized AUC were identified, which could improve the performance of XFCT.
Collapse
|
6
|
Chen L, Tsui BMW, Mok GSP. Design and evaluation of two multi-pinhole collimators for brain SPECT. Ann Nucl Med 2017; 31:636-648. [DOI: 10.1007/s12149-017-1195-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 07/07/2017] [Indexed: 11/29/2022]
|
7
|
Beijst C, Elschot M, van der Velden S, de Jong HWAM. Multimodality calibration for simultaneous fluoroscopic and nuclear imaging. EJNMMI Phys 2016; 3:20. [PMID: 27576333 PMCID: PMC5005238 DOI: 10.1186/s40658-016-0156-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 08/18/2016] [Indexed: 02/08/2023] Open
Abstract
Background Simultaneous real-time fluoroscopic and nuclear imaging could benefit image-guided (oncological) procedures. To this end, a hybrid modality is currently being developed by our group, by combining a c-arm with a gamma camera and a four-pinhole collimator. Accurate determination of the system parameters that describe the position of the x-ray tube, x-ray detector, gamma camera, and collimators is crucial to optimize image quality. The purpose of this study was to develop a calibration method that estimates the system parameters used for reconstruction. A multimodality phantom consisting of five point sources was created. First, nuclear and fluoroscopic images of the phantom were acquired at several distances from the image intensifier. The system parameters were acquired using physical measurement, and multimodality images of the phantom were reconstructed. The resolution and co-registration error of the point sources were determined as a measure of image quality. Next, the system parameters were estimated using a calibration method, which adjusted the parameters in the reconstruction algorithm, until the resolution and co-registration were optimized. For evaluation, multimodality images of a second set of phantom acquisitions were reconstructed using calibrated parameter sets. Subsequently, the resolution and co-registration error of the point sources were determined as a measure of image quality. This procedure was performed five times for different noise simulations. In addition, simultaneously acquired fluoroscopic and nuclear images of two moving syringes were obtained with parameter sets from before and after calibration. Results The mean FWHM was significantly lower after calibration than before calibration for 21 out of 25 point sources. The mean co-registration error was significantly lower after calibration than before calibration for all point sources. The simultaneously acquired fluoroscopic and nuclear images showed improved co-registration after calibration as compared with before calibration. Conclusions A calibration method was presented that improves the resolution and co-registration of simultaneously acquired hybrid fluoroscopic and nuclear images by estimating the geometric parameter set as compared with a parameter set acquired by direct physical measurement. Electronic supplementary material The online version of this article (doi:10.1186/s40658-016-0156-1) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Casper Beijst
- Radiology and Nuclear Medicine, UMC Utrecht, P.O. Box 85500, 3508 GA, Utrecht, the Netherlands. .,Image Sciences Institute, UMC Utrecht, P.O. Box 85500, 3508 GA, Utrecht, the Netherlands.
| | - Mattijs Elschot
- Radiology and Nuclear Medicine, UMC Utrecht, P.O. Box 85500, 3508 GA, Utrecht, the Netherlands.,Department of Circulation and Medical Imaging, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway
| | - Sandra van der Velden
- Radiology and Nuclear Medicine, UMC Utrecht, P.O. Box 85500, 3508 GA, Utrecht, the Netherlands.,Image Sciences Institute, UMC Utrecht, P.O. Box 85500, 3508 GA, Utrecht, the Netherlands
| | - Hugo W A M de Jong
- Radiology and Nuclear Medicine, UMC Utrecht, P.O. Box 85500, 3508 GA, Utrecht, the Netherlands
| |
Collapse
|
8
|
Beijst C, Elschot M, Viergever MA, de Jong HWAM. Toward Simultaneous Real-Time Fluoroscopic and Nuclear Imaging in the Intervention Room. Radiology 2015; 278:232-8. [PMID: 26043264 DOI: 10.1148/radiol.2015142749] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To investigate the technical feasibility of hybrid simultaneous fluoroscopic and nuclear imaging. MATERIALS AND METHODS An x-ray tube, an x-ray detector, and a gamma camera were positioned in one line, enabling imaging of the same field of view. Since a straightforward combination of these elements would block the lines of view, a gamma camera setup was developed to be able to view around the x-ray tube. A prototype was built by using a mobile C-arm and a gamma camera with a four-pinhole collimator. By using the prototype, test images were acquired and sensitivity, resolution, and coregistration error were analyzed. RESULTS Nuclear images (two frames per second) were acquired simultaneously with fluoroscopic images. Depending on the distance from point source to detector, the system resolution was 1.5-1.9-cm full width at half maximum, the sensitivity was (0.6-1.5) × 10(-5) counts per decay, and the coregistration error was -0.13 to 0.15 cm. With good spatial and temporal alignment of both modalities throughout the field of view, fluoroscopic images can be shown in grayscale and corresponding nuclear images in color overlay. CONCLUSION Measurements obtained with the hybrid imaging prototype device that combines simultaneous fluoroscopic and nuclear imaging of the same field of view have demonstrated the feasibility of real-time simultaneous hybrid imaging in the intervention room.
Collapse
Affiliation(s)
- Casper Beijst
- From the Department of Radiology and Nuclear Medicine (C.B., M.E., H.W.A.M.d.J.) and Image Sciences Institute (C.B., M.A.V.), University Medical Center Utrecht, Mail E01.132, PO Box 85500, 3508GA Utrecht, the Netherlands
| | - Mattijs Elschot
- From the Department of Radiology and Nuclear Medicine (C.B., M.E., H.W.A.M.d.J.) and Image Sciences Institute (C.B., M.A.V.), University Medical Center Utrecht, Mail E01.132, PO Box 85500, 3508GA Utrecht, the Netherlands
| | - Max A Viergever
- From the Department of Radiology and Nuclear Medicine (C.B., M.E., H.W.A.M.d.J.) and Image Sciences Institute (C.B., M.A.V.), University Medical Center Utrecht, Mail E01.132, PO Box 85500, 3508GA Utrecht, the Netherlands
| | - Hugo W A M de Jong
- From the Department of Radiology and Nuclear Medicine (C.B., M.E., H.W.A.M.d.J.) and Image Sciences Institute (C.B., M.A.V.), University Medical Center Utrecht, Mail E01.132, PO Box 85500, 3508GA Utrecht, the Netherlands
| |
Collapse
|
9
|
Beijst C, Elschot M, Viergever MA, de Jong HWAM. A parallel-cone collimator for high-energy SPECT. J Nucl Med 2015; 56:476-82. [PMID: 25655627 DOI: 10.2967/jnumed.114.149658] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
UNLABELLED In SPECT using high-energy photon-emitting isotopes, such as (131)I, parallel-hole collimators with thick septa are required to limit septal penetration, at the cost of sensitivity and resolution. This study investigated a parallel-hole collimator with cone-shaped holes, which was designed to limit collimator penetration while preserving resolution and sensitivity. The objective was to demonstrate that a single-slice prototype of the parallel-cone (PC) collimator was capable of improving the image quality of high-energy SPECT. METHODS The image quality of the PC collimator was quantitatively compared with that of clinically used low-energy high-resolution (LEHR; for (99m)Tc) and high-energy general-purpose (HEGP; for (131)I and (18)F) parallel-hole collimators. First, Monte Carlo simulations of single and double point sources were performed to assess sensitivity and resolution by comparing point-spread functions (PSFs). Second, a prototype PC collimator was used in an experimental phantom study to assess and compare contrast recovery coefficients and image noise. RESULTS Monte Carlo simulations showed reduced broadening of the PSF due to collimator penetration for the PC collimator as compared with the HEGP collimator (e.g., 0.9 vs. 1.4 cm in full width at half maximum for (131)I). Simulated double point sources placed 2 cm apart were separately detectable for the PC collimator, whereas this was not the case for (131)I and (18)F at distances from the collimator face of 10 cm or more for the HEGP collimator. The sensitivity, measured over the simulated profiles as the total amount of counts per decay, was found to be higher for the LEHR and HEGP collimators than for the PC collimator (e.g., 3.1 × 10(-5) vs. 2.9 × 10(-5) counts per decay for (131)I). However, at equal noise level, phantom measurements showed that contrast recovery coefficients were similar for the PC and LEHR collimators for (99m)Tc but that the PC collimator significantly improved the contrast recovery coefficients as compared with the HEGP collimator for (131)I and (18)F. CONCLUSION High-energy SPECT imaging with a single-slice prototype of the proposed PC collimator has shown the potential for significantly improved image quality in comparison with standard parallel-hole collimators.
Collapse
Affiliation(s)
- Casper Beijst
- Radiology and Nuclear Medicine, UMC Utrecht, Utrecht, The Netherlands; and Image Sciences Institute, UMC Utrecht, Utrecht, The Netherlands
| | - Mattijs Elschot
- Radiology and Nuclear Medicine, UMC Utrecht, Utrecht, The Netherlands; and
| | - Max A Viergever
- Image Sciences Institute, UMC Utrecht, Utrecht, The Netherlands
| | - Hugo W A M de Jong
- Radiology and Nuclear Medicine, UMC Utrecht, Utrecht, The Netherlands; and
| |
Collapse
|
10
|
Matsunari I, Miyazaki Y, Kobayashi M, Nishi K, Mizutani A, Kawai K, Hayashi A, Komatsu R, Yonezawa S, Kinuya S. Performance evaluation of the eXplore speCZT preclinical imaging system. Ann Nucl Med 2014; 28:484-97. [PMID: 24610679 DOI: 10.1007/s12149-014-0828-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2013] [Accepted: 02/19/2014] [Indexed: 11/29/2022]
Abstract
OBJECTIVE The eXplore speCZT is a recently introduced cadmium zinc telluride-based preclinical SPECT system that has a stationary detector design with interchangeable rotating collimators. Our aim was to evaluate the performance of the eXplore speCZT using 99mTc-sources. In particular, the image quality was assessed using the National Electrical Manufacturers Association NU-4 image quality phantom as well as an in vivo mouse. METHODS Energy resolution, sensitivity and spatial resolution were measured using 99mTc sources. Image quality was assessed using NU-4 image quality phantom. The measurements were performed for 4 available collimators: (1) mouse 7-pinhole collimator (mouse PH); (2) mouse 8-slit collimator (mouse SL); (3) rat 5-pinhole collimator (rat PH); and (4) rat 5-slit collimator (rat SL). Furthermore, a mouse bone imaging study was performed using mouse PH and mouse SL. RESULTS The system achieved the energy resolution of 5.5% in full-width at half maximum (FWHM) at 140 keV using a 99mTc source. Without resolution recovery function, the system provided a near millimeter transaxial and axial spatial resolution using mouse PH. Mouse SL and rat SL provided reasonably good transaxial (1.79-2.00 mm in FWHM), but much worse axial resolutions (4.55-4.96 mm in FWHM). The use of resolution recovery significantly improved spatial resolution by in average 31±3 or 35±4% in FWHM or full-width at tenth maximum, respectively. In particular, a sub-millimeter resolution of 0.71 mm in FWHM was achieved in either transaxial or axial direction with mouse PH. Using NU-4 phantom, the uniformity of slit collimators as expressed as percentage standard deviation was generally better than that of pinhole collimators. The use of resolution recovery substantially improved uniformity for all the collimators tested, but caused some overestimation in recovery coefficient. Reconstruction settings such as iteration or subset number significantly affected image quality measures. Finally, bone images of acceptable quality were obtained in in vivo mouse using mouse PH with resolution recovery. CONCLUSIONS The overall performance shows that the eXplore speCZT system is suitable for preclinical imaging-based research using small-animals.
Collapse
Affiliation(s)
- Ichiro Matsunari
- Clinical Research Department, The Medical and Pharmacological Research Center Foundation, Wo 32, Inoyama, Hakui, Ishikawa, 925-0613, Japan,
| | | | | | | | | | | | | | | | | | | |
Collapse
|
11
|
Zhou L, Vunckx K, Nuyts J. Multi-pinhole SPECT calibration: influence of data noise and systematic orbit deviations. IEEE TRANSACTIONS ON MEDICAL IMAGING 2011; 30:1795-1807. [PMID: 21536518 DOI: 10.1109/tmi.2011.2148123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The geometry of a single pinhole SPECT system with circular orbit can be uniquely determined from a measurement of three point sources, provided that at least two inter-point distances are known. In contrast, it has been shown mathematically that, for a multi-pinhole SPECT system with circular orbit, only two point sources are needed, and the knowledge of the distance between them is not required. In this paper, we report that this conclusion only holds if the motion of the camera is perfectly circular. In reality, the detector heads systematically slightly deviate from the circular orbit, which may introduce non-negligible bias in the estimated parameters and degrade the reconstructed image. An analytical linear model was extended to estimate the influence of both data noise and systematic deviations on the accuracy of the calibration and on the image quality of the reconstruction. It turns out that applying the knowledge of the distances greatly reduces the reconstruction error, especially in the presence of systematic deviations. In addition, we propose that instead of using the information about the distances between the point sources, it is more straightforward to use the knowledge about the distances between the pinhole apertures during multi-pinhole calibration. The two distance-fixing approaches yield similar reconstruction accuracy. Our theoretical results are supported by reconstruction images of a Jaszczak-type phantom scan.
Collapse
Affiliation(s)
- Lin Zhou
- Department of NuclearMedicine, K. U. Leuven, B-3000 Leuven, Belgium.
| | | | | |
Collapse
|
12
|
|
13
|
Li YS, Oldendick JE, Chang W. Analytic derivation of pinhole collimation sensitivity for a general source model using spherical harmonics. Phys Med Biol 2010; 55:2727-41. [PMID: 20400812 DOI: 10.1088/0031-9155/55/9/020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
14
|
Nuyts J, Vunckx K, Defrise M, Vanhove C. Small animal imaging with multi-pinhole SPECT. Methods 2009; 48:83-91. [DOI: 10.1016/j.ymeth.2009.03.015] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2008] [Accepted: 03/11/2009] [Indexed: 10/21/2022] Open
|
15
|
Shokouhi S, Metzler SD, Wilson DW, Peterson TE. Multi-pinhole collimator design for small-object imaging with SiliSPECT: a high-resolution SPECT. Phys Med Biol 2009; 54:207-25. [PMID: 19088387 PMCID: PMC2892935 DOI: 10.1088/0031-9155/54/2/003] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We have designed a multi-pinhole collimator for a dual-headed, stationary SPECT system that incorporates high-resolution silicon double-sided strip detectors. The compact camera design of our system enables imaging at source-collimator distances between 20 and 30 mm. Our analytical calculations show that using knife-edge pinholes with small-opening angles or cylindrically shaped pinholes in a focused, multi-pinhole configuration in combination with this camera geometry can generate narrow sensitivity profiles across the field of view that can be useful for imaging small objects at high sensitivity and resolution. The current prototype system uses two collimators each containing 127 cylindrically shaped pinholes that are focused toward a target volume. Our goal is imaging objects such as a mouse brain, which could find potential applications in molecular imaging.
Collapse
MESH Headings
- Animals
- Biophysical Phenomena
- Brain/anatomy & histology
- Brain/diagnostic imaging
- Equipment Design
- Imaging, Three-Dimensional
- Mice
- Models, Theoretical
- Phantoms, Imaging
- Scattering, Radiation
- Tomography, Emission-Computed, Single-Photon/instrumentation
- Tomography, Emission-Computed, Single-Photon/methods
- Tomography, Emission-Computed, Single-Photon/statistics & numerical data
Collapse
Affiliation(s)
- S Shokouhi
- Vanderbilt University Institute of Imaging Science, Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, USA.
| | | | | | | |
Collapse
|