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Poitrasson-Rivière A, Moody JB, Renaud JM, Hagio T, Arida-Moody L, Buckley C, Weinberg RL, Ficaro EP, Murthy VL. Impact of residual subtraction on myocardial blood flow and reserve estimates from rapid dynamic PET protocols. J Nucl Cardiol 2022; 29:2262-2270. [PMID: 34780036 DOI: 10.1007/s12350-021-02837-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 09/27/2021] [Indexed: 12/29/2022]
Abstract
BACKGROUND 13N-ammonia and 18F-flurpiridaz require longer delays between rest and stress studies to allow for decay, lowering clinical throughput. In this study, we investigated the impact of residual subtraction on MBF and MFR estimates, as well as its effects on diagnostic accuracy. METHODS We retrospectively analyzed 63 patients who underwent a dynamic ammonia rest/stress study and 231 patients from the flurpiridaz 301 trial. Residual subtraction was performed by subtracting the mean pre-injection activity in each sampled region from that region's time activity curve. Corrected and uncorrected MBF and MFR were analyzed. Diagnostic accuracy was compared to quantitative coronary angiograms (QCA) for the flurpiridaz population. RESULTS With delays between injections above 3 half-lives, and a doubled stress dose, residual activity did not meaningfully increase ammonia MBF (< 5%). For shorter injection delays, stress MBF was overestimated by 13.6% ± 5.0% (P < .001). Residual activity had a large effect on flurpiridaz stress MBF, overestimating it by 37.9% ± 23.2% (P < .001). Comparison to QCA showed a significant improvement in AUC with residual subtraction (from 0.748 to 0.831, P = .001). MFR yielded similar results. CONCLUSIONS Accounting for residual activity has a marked impact on stress MBF and MFR and improves diagnostic accuracy relative to QCA.
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Affiliation(s)
| | - Jonathan B Moody
- INVIA Medical Imaging Solutions, 3025 Boardwalk Drive, Suite 200, Ann Arbor, MI, 48108, USA
| | - Jennifer M Renaud
- INVIA Medical Imaging Solutions, 3025 Boardwalk Drive, Suite 200, Ann Arbor, MI, 48108, USA
| | - Tomoe Hagio
- INVIA Medical Imaging Solutions, 3025 Boardwalk Drive, Suite 200, Ann Arbor, MI, 48108, USA
| | - Liliana Arida-Moody
- Division of Cardiovascular Medicine, Department of Internal Medicine and Frankel Cardiovascular Center, University of Michigan, Ann Arbor, MI, USA
| | | | - Richard L Weinberg
- Division of Cardiology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Edward P Ficaro
- INVIA Medical Imaging Solutions, 3025 Boardwalk Drive, Suite 200, Ann Arbor, MI, 48108, USA
- Division of Cardiovascular Medicine, Department of Internal Medicine and Frankel Cardiovascular Center, University of Michigan, Ann Arbor, MI, USA
| | - Venkatesh L Murthy
- Division of Cardiovascular Medicine, Department of Internal Medicine and Frankel Cardiovascular Center, University of Michigan, Ann Arbor, MI, USA
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Tong J, Wang C, Liu H. Temporal information guided dynamic dual-tracer PET signal separation network. Med Phys 2022; 49:4585-4598. [PMID: 35396705 DOI: 10.1002/mp.15566] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 02/21/2021] [Accepted: 01/24/2022] [Indexed: 11/09/2022] Open
Abstract
PURPOSE The difficulty of dynamic dual-tracer positron emission tomography (PET) technology is to separate the complete single-tracer information from mixed dual-tracer. Traditional methods cannot separate single injection single-scan dynamic dual-tracer PET images. In this paper, we propose a deep learning framework based on gated recurrent unit (GRU) network and evaluate its performance with simulation experiments and realistic monkey data. METHODS The proposed single-scan dynamic dual-tracer PET image separation network consists of three parts, including encoder, separation and decoder module. Encoder part is to map the mixed time activity curves (TACs) from the low-dimensional space to the high-dimensional space to get mixed weight vector matrix. Separation part is to capture the temporal information of mixed weight vector matrix using bi-directional GRU (bi-GRU) layer to obtain the single-tracer masks, and the decoding part remaps the high-dimensional single-tracer weight vector matrix to the low-dimensional space to obtain two separated single tracers. RESULTS In the simulation experiments under different tracers, phantoms, noise levels, arterial input function (AIF) and k-parameter with Gaussian random, compared to the stacked auto encoder (SAE) network and traditional background subtraction method, GRU-based network has better performance with low bias and mean squared error (MSE). In the realistic study, the image results of GRU network have higher mean structural similarity (MSSIM), and peak signal to noise ratio (PSNR). CONCLUSIONS This study demonstrates the feasibility of temporal information guided neural network in single-injection single-scan dynamic dual-tracer PET images separation. The GRU-based network uses TAC temporal information without AIFs to make the separation results more robust and accurate, which significantly outperforms state-of-the-art method qualitatively and quantitatively. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Junyi Tong
- State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou, 310027, China
| | - Chunxia Wang
- State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou, 310027, China
| | - Huafeng Liu
- State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou, 310027, China
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Beekman FJ, Kamphuis C, Koustoulidou S, Ramakers RM, Goorden MC. Positron range-free and multi-isotope tomography of positron emitters. Phys Med Biol 2021; 66:065011. [PMID: 33578400 DOI: 10.1088/1361-6560/abe5fc] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Despite improvements in small animal PET instruments, many tracers cannot be imaged at sufficiently high resolutions due to positron range, while multi-tracer PET is hampered by the fact that all annihilation photons have equal energies. Here we realize multi-isotope and sub-mm resolution PET of isotopes with several mm positron range by utilizing prompt gamma photons that are commonly neglected. A PET-SPECT-CT scanner (VECTor/CT, MILabs, The Netherlands) equipped with a high-energy cluster-pinhole collimator was used to image 124I and a mix of 124I and 18F in phantoms and mice. In addition to positrons (mean range 3.4 mm) 124I emits large amounts of 603 keV prompt gammas that-aided by excellent energy discrimination of NaI-were selected to reconstruct 124I images that are unaffected by positron range. Photons detected in the 511 keV window were used to reconstruct 18F images. Images were reconstructed iteratively using an energy dependent matrix for each isotope. Correction of 18F images for contamination with 124I annihilation photons was performed by Monte Carlo based range modelling and scaling of the 124I prompt gamma image before subtracting it from the 18F image. Additionally, prompt gamma imaging was tested for 89Zr that emits very high-energy prompts (909 keV). In Derenzo resolution phantoms 0.75 mm rods were clearly discernable for 124I, 89Zr and for simultaneously acquired 124I and 18F imaging. Image quantification in phantoms with reservoirs filled with both 124I and 18F showed excellent separation of isotopes and high quantitative accuracy. Mouse imaging showed uptake of 124I in tiny thyroid parts and simultaneously injected 18F-NaF in bone structures. The ability to obtain PET images at sub-mm resolution both for isotopes with several mm positron range and for multi-isotope PET adds to many other unique capabilities of VECTor's clustered pinhole imaging, including simultaneous sub-mm PET-SPECT and theranostic high energy SPECT.
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Affiliation(s)
- F J Beekman
- 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
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Wilk B, Wisenberg G, Dharmakumar R, Thiessen JD, Goldhawk DE, Prato FS. Hybrid PET/MR imaging in myocardial inflammation post-myocardial infarction. J Nucl Cardiol 2020; 27:2083-2099. [PMID: 31797321 PMCID: PMC7391987 DOI: 10.1007/s12350-019-01973-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 11/13/2019] [Accepted: 11/14/2019] [Indexed: 01/24/2023]
Abstract
Hybrid PET/MR imaging is an emerging imaging modality combining positron emission tomography (PET) and magnetic resonance imaging (MRI) in the same system. Since the introduction of clinical PET/MRI in 2011, it has had some impact (e.g., imaging the components of inflammation in myocardial infarction), but its role could be much greater. Many opportunities remain unexplored and will be highlighted in this review. The inflammatory process post-myocardial infarction has many facets at a cellular level which may affect the outcome of the patient, specifically the effects on adverse left ventricular remodeling, and ultimately prognosis. The goal of inflammation imaging is to track the process non-invasively and quantitatively to determine the best therapeutic options for intervention and to monitor those therapies. While PET and MRI, acquired separately, can image aspects of inflammation, hybrid PET/MRI has the potential to advance imaging of myocardial inflammation. This review contains a description of hybrid PET/MRI, its application to inflammation imaging in myocardial infarction and the challenges, constraints, and opportunities in designing data collection protocols. Finally, this review explores opportunities in PET/MRI: improved registration, partial volume correction, machine learning, new approaches in the development of PET and MRI pulse sequences, and the use of novel injection strategies.
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Affiliation(s)
- B Wilk
- Department of Medical Imaging, Western University, London, Canada.
- Lawson Health Research Institute, London, Canada.
- Collaborative Graduate Program in Molecular Imaging, Western University, London, Canada.
| | - G Wisenberg
- Department of Medical Imaging, Western University, London, Canada
- MyHealth Centre, Arva, Canada
| | - R Dharmakumar
- Biomedical Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - J D Thiessen
- Department of Medical Imaging, Western University, London, Canada
- Lawson Health Research Institute, London, Canada
- Collaborative Graduate Program in Molecular Imaging, Western University, London, Canada
| | - D E Goldhawk
- Department of Medical Imaging, Western University, London, Canada
- Lawson Health Research Institute, London, Canada
- Collaborative Graduate Program in Molecular Imaging, Western University, London, Canada
| | - F S Prato
- Department of Medical Imaging, Western University, London, Canada
- Lawson Health Research Institute, London, Canada
- Collaborative Graduate Program in Molecular Imaging, Western University, London, Canada
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Wang G, Rahmim A, Gunn RN. PET Parametric Imaging: Past, Present, and Future. IEEE TRANSACTIONS ON RADIATION AND PLASMA MEDICAL SCIENCES 2020; 4:663-675. [PMID: 33763624 PMCID: PMC7983029 DOI: 10.1109/trpms.2020.3025086] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Positron emission tomography (PET) is actively used in a diverse range of applications in oncology, cardiology, and neurology. The use of PET in the clinical setting focuses on static (single time frame) imaging at a specific time-point post radiotracer injection and is typically considered as semi-quantitative; e.g. standardized uptake value (SUV) measures. In contrast, dynamic PET imaging requires increased acquisition times but has the advantage that it measures the full spatiotemporal distribution of a radiotracer and, in combination with tracer kinetic modeling, enables the generation of multiparametric images that more directly quantify underlying biological parameters of interest, such as blood flow, glucose metabolism, and receptor binding. Parametric images have the potential for improved detection and for more accurate and earlier therapeutic response assessment. Parametric imaging with dynamic PET has witnessed extensive research in the past four decades. In this paper, we provide an overview of past and present activities and discuss emerging opportunities in the field of parametric imaging for the future.
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Affiliation(s)
- Guobao Wang
- Department of Radiology, University of California Davis Health, Sacramento, CA 95817, USA
| | - Arman Rahmim
- University of British Columbia, Vancouver, BC, Canada
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Zuo Y, Badawi RD, Foster CC, Smith T, López JE, Wang G. Multiparametric Cardiac 18F-FDG PET in Humans: Kinetic Model Selection and Identifiability Analysis. IEEE TRANSACTIONS ON RADIATION AND PLASMA MEDICAL SCIENCES 2020; 4:759-767. [PMID: 33778234 DOI: 10.1109/trpms.2020.3031274] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Cardiac 18F-FDG PET has been used in clinics to assess myocardial glucose metabolism. Its ability for imaging myocardial glucose transport, however, has rarely been exploited in clinics. Using the dynamic FDG-PET scans of ten patients with coronary artery disease, we investigate in this paper appropriate dynamic scan and kinetic modeling protocols for efficient quantification of myocardial glucose transport. Three kinetic models and the effect of scan duration were evaluated by using statistical fit quality, assessing the impact on kinetic quantification, and analyzing the practical identifiability. The results show that the kinetic model selection depends on the scan duration. The reversible two-tissue model was needed for a one-hour dynamic scan. The irreversible two-tissue model was optimal for a scan duration of around 10-15 minutes. If the scan duration was shortened to 2-3 minutes, a one-tissue model was the most appropriate. For global quantification of myocardial glucose transport, we demonstrated that an early dynamic scan with a duration of 10-15 minutes and irreversible kinetic modeling was comparable to the full one-hour scan with reversible kinetic modeling. Myocardial glucose transport quantification provides an additional physiological parameter on top of the existing assessment of glucose metabolism and has the potential to enable single tracer multiparametric imaging in the myocardium.
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Affiliation(s)
- Yang Zuo
- Department of Radiology, University of California Davis Medical Center, Sacramento, CA 9817
| | - Ramsey D Badawi
- Department of Radiology and Department of Biomedical Engineering, University of California Davis Medical Center, Sacramento, CA 9817
| | - Cameron C Foster
- Department of Radiology, University of California Davis Medical Center, Sacramento, CA 9817
| | - Thomas Smith
- Department of Internal Medicine, University of California Davis Medical Center, Sacramento, CA 9817
| | - Javier E López
- Department of Internal Medicine, University of California Davis Medical Center, Sacramento, CA 9817
| | - Guobao Wang
- Department of Radiology, University of California Davis Medical Center, Sacramento, CA 9817
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Velasco C, Mota-Cobián A, Mateo J, España S. Explicit measurement of multi-tracer arterial input function for PET imaging using blood sampling spectroscopy. EJNMMI Phys 2020; 7:7. [PMID: 32030519 PMCID: PMC7005194 DOI: 10.1186/s40658-020-0277-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Accepted: 01/27/2020] [Indexed: 11/18/2022] Open
Abstract
Background Conventional PET imaging has usually been limited to a single tracer per scan. We propose a new technique for multi-tracer PET imaging that uses dynamic imaging and multi-tracer compartment modeling including an explicitly derived arterial input function (AIF) for each tracer using blood sampling spectroscopy. For that purpose, at least one of the co-injected tracers must be based on a non-pure positron emitter. Methods The proposed technique was validated in vivo by performing cardiac PET/CT studies on three healthy pigs injected with 18FDG (viability) and 68Ga-DOTA (myocardial blood flow and extracellular volume fraction) during the same acquisition. Blood samples were collected during the PET scan, and separated AIF for each tracer was obtained by spectroscopic analysis. A multi-tracer compartment model was applied to the myocardium in order to obtain the distribution of each tracer at the end of the PET scan. Relative activities of both tracers and tracer uptake were obtained and compared with the values obtained by ex vivo analysis of excised myocardial tissue segments. Results A high correlation was obtained between multi-tracer PET results, and those obtained from ex vivo analysis (18FDG relative activity: r = 0.95, p < 0.0001; SUV: r = 0.98, p < 0.0001). Conclusions The proposed technique allows performing PET scans with two tracers during the same acquisition obtaining separate information for each tracer.
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Affiliation(s)
- Carlos Velasco
- Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain.,Departamento de Estructura de la Materia, Física Térmica y Electrónica, Facultad de Ciencias Físicas, Ciudad Universitaria, Universidad Complutense de Madrid, IdISSC, 28040, Madrid, Spain
| | - Adriana Mota-Cobián
- Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain.,Departamento de Estructura de la Materia, Física Térmica y Electrónica, Facultad de Ciencias Físicas, Ciudad Universitaria, Universidad Complutense de Madrid, IdISSC, 28040, Madrid, Spain
| | - Jesús Mateo
- Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
| | - Samuel España
- Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain. .,Departamento de Estructura de la Materia, Física Térmica y Electrónica, Facultad de Ciencias Físicas, Ciudad Universitaria, Universidad Complutense de Madrid, IdISSC, 28040, Madrid, Spain.
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Guehl NJ, Pelletier-Galarneau M, Wooten DW, Guerrero JL, Kas A, Normandin MD, Fakhri GE, Alpert NM. Preclinical Validation of a Single-Scan Rest/Stress Imaging Technique for 13N-Ammonia Positron Emission Tomography Cardiac Perfusion Studies. Circ Cardiovasc Imaging 2020; 13:e009407. [PMID: 31959009 DOI: 10.1161/circimaging.119.009407] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND We previously proposed a technique for quantitative measurement of rest and stress absolute myocardial blood flow (MBF) using a 2-injection single-scan imaging session. Recently, we validated the method in a pig model for the long-lived radiotracer 18F-Flurpiridaz with adenosine as a pharmacological stressor. The aim of the present work is to validate our technique for 13NH3. METHODS Nine studies were performed in 6 pigs; 5 studies were done in the native state and 4 after infarction of the left anterior descending artery. Each study consisted of 3 dynamic scans: a 2-injection rest-rest single-scan acquisition (scan A), a 2-injection rest/stress single-scan acquisition (scan B), and a conventional 1-injection stress acquisition (scan C). Variable doses of adenosine combined with dobutamine were administered to induce a wide range of MBF. The 2-injection single-scan measurements were fitted with our nonstationary kinetic model (MGH2). In 4 studies, 13NH3 injections were paired with microsphere injections. MBF estimates obtained with our method were compared with those obtained with the standard method and with microspheres. We used a model-based method to generate separate rest and stress perfusion images. RESULTS In the absence of stress (scan A), the MBF values estimated by MGH2 were nearly the same for the 2-radiotracer injections (mean difference: 0.067±0.070 mL·min-1·cc-1, limits of agreement: [-0.070 to 0.204] mL·min-1·cc-1), showing good repeatability. Bland-Altman analyses demonstrated very good agreement with the conventional method for both rest (mean difference: -0.034±0.035 mL·min-1·cc-1, limits of agreement: [-0.103 to 0.035] mL·min-1·cc-1) and stress (mean difference: 0.057±0.361 mL·min-1·cc-1, limits of agreement: [-0.651 to 0.765] mL·min-1·cc-1) MBF measurements. Positron emission tomography and microsphere MBF measurements correlated closely. Very good quality perfusion images were obtained. CONCLUSIONS This study provides in vivo validation of our single-scan rest-stress method for 13NH3 measurements. The 13NH3 rest/stress myocardial perfusion imaging procedure can be compressed into a single positron emission tomography scan session lasting less than 15 minutes.
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Affiliation(s)
- Nicolas J Guehl
- Department of Radiology, Gordon Center for Medical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston (N.J.G., M.P.-G., D.W.W., J.L.G., M.D.N., G.E.F., N.M.A.)
| | - Matthieu Pelletier-Galarneau
- Department of Radiology, Gordon Center for Medical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston (N.J.G., M.P.-G., D.W.W., J.L.G., M.D.N., G.E.F., N.M.A.).,Department of Radiology and Nuclear Medicine, Montreal Heart Institute, Québec, CA (M.P.-G.)
| | - Dustin W Wooten
- Department of Radiology, Gordon Center for Medical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston (N.J.G., M.P.-G., D.W.W., J.L.G., M.D.N., G.E.F., N.M.A.)
| | - J Luis Guerrero
- Department of Radiology, Gordon Center for Medical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston (N.J.G., M.P.-G., D.W.W., J.L.G., M.D.N., G.E.F., N.M.A.)
| | - Aurélie Kas
- AP-HP, Department of Nuclear Medicine, Pitié-Salpêtrière Hospital, Sorbonne University, UPMC Paris 06, CNRS UMR 7371, INSERM U1146, France (A.K.)
| | - Marc D Normandin
- Department of Radiology, Gordon Center for Medical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston (N.J.G., M.P.-G., D.W.W., J.L.G., M.D.N., G.E.F., N.M.A.)
| | - Georges El Fakhri
- Department of Radiology, Gordon Center for Medical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston (N.J.G., M.P.-G., D.W.W., J.L.G., M.D.N., G.E.F., N.M.A.)
| | - Nathaniel M Alpert
- Department of Radiology, Gordon Center for Medical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston (N.J.G., M.P.-G., D.W.W., J.L.G., M.D.N., G.E.F., N.M.A.)
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Xu J, Liu H. Deep-Learning-Based Separation of a Mixture of Dual-Tracer Single-Acquisition PET Signals With Equal Half-Lives: A Simulation Study. IEEE TRANSACTIONS ON RADIATION AND PLASMA MEDICAL SCIENCES 2019. [DOI: 10.1109/trpms.2019.2897120] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Fang YHD, Liu YC, Ho KC, Kuo FC, Yang CF, Yen TC, Hsieh IC. Single-scan rest/stress imaging with 99mTc-Sestamibi and cadmium zinc telluride-based SPECT for hyperemic flow quantification: A feasibility study evaluated with cardiac magnetic resonance imaging. PLoS One 2017; 12:e0183402. [PMID: 28817662 PMCID: PMC5560722 DOI: 10.1371/journal.pone.0183402] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 07/14/2017] [Indexed: 12/21/2022] Open
Abstract
Introduction We aimed to evaluate whether the hyperemic myocardial blood flow (MBF) can be estimated using cadmium zinc telluride (CZT)-based single-photon emission computed tomography (SPECT) cameras with a single, rapid rest/stress dynamic scan. Dynamic contrast-enhanced (DCE) cardiac magnetic resonance imaging (MRI) was used as a reference modality for flow measurement. Materials and methods The proposed protocol included both the rest and stress acquisitions within a 24-min scan. Patients were first injected with 99mTc-Sestamibi at the resting state. Sixty minutes after the first injection, the subject was positioned via scintigraphy, after which the list-mode data acquisition was initiated and continued for 24 minutes. Five minutes after data acquisition was initiated, a stressed state was induced via dipyridamole infusion, after which a second dose of 99mTc-Sestamibi was injected. Dynamic SPECT images were reconstructed for all subjects, who also underwent T1-weighted cardiac DCE-MRI performed on days other than those of the SPECT studies. MBF values were estimated for the rest and stress MRI studies, and for the stress portion of the SPECT study. The SPECT-measured hyperemic MBF was compared with the MR-measured hyperemic MBF and coronary flow reserve (CFR), based on the regions of interest. Results A total of 30 subjects were included in this study. The hyperemic MBF estimated from SPECT showed a strong correlation with the MR-measured hyperemic MBF (r2 = 0.76) and a modest correlation with the MR-measured CFR (r2 = 0.56). Using MR-measured CFR <1.3 as a cutoff for coronary stenosis, we found that the SPECT-measured hyperemic MBF served as a useful clinical index with 94% sensitivity, 90% specificity, and 93% accuracy. Conclusions Hyperemic MBF can be measured with a rapid, single-scan rest/stress study with CZT-based SPECT cameras.
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Affiliation(s)
- Yu-Hua Dean Fang
- Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan
| | - Yuan-Chang Liu
- Department of Medical Imaging and Intervention, Chang Gung Memorial Hospital, Linkou, Taiwan
| | - Kung-Chu Ho
- Department of Nuclear Medicine, Chang Gung Memorial Hospital, Linkou, Taiwan
| | - Feng-Cheng Kuo
- Department of Nuclear Medicine, Chang Gung Memorial Hospital, Linkou, Taiwan
| | - Ching-Fang Yang
- Department of Medical Imaging and Radiological Sciences, Chang Gung University, Taoyuan, Taiwan
| | - Tzu-Chen Yen
- Department of Nuclear Medicine, Chang Gung Memorial Hospital, Linkou, Taiwan
- Center for Advanced Molecular Imaging and Translation & Cyclotron Center, Chang Gung Memorial Hospital, Linkou, Taiwan
- * E-mail: (TY); (IH)
| | - I-Chang Hsieh
- Department of Cardiology, Chang Gung Memorial Hospital, Linkou, Taiwan
- * E-mail: (TY); (IH)
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11
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Guehl NJ, Normandin MD, Wooten DW, Rozen G, Sitek A, Ruskin J, Shoup TM, Ptaszek LM, El Fakhri G, Alpert NM. Single-scan rest/stress imaging: validation in a porcine model with 18F-Flurpiridaz. Eur J Nucl Med Mol Imaging 2017; 44:1538-1546. [PMID: 28365789 DOI: 10.1007/s00259-017-3684-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 03/17/2017] [Indexed: 11/27/2022]
Abstract
PURPOSE 18F-labeled myocardial flow agents are becoming available for clinical application but the ∼2 hour half-life of 18F complicates their clinical application for rest-stress measurements. The goal of this work is to evaluate in a pig model a single-scan method which provides quantitative rest-stress blood flow in less than 15 minutes. METHODS Single-scan rest-stress measurements were made using 18F-Flurpiridaz. Nine scans were performed in healthy pigs and seven scans were performed in injured pigs. A two-injection, single-scan protocol was used in which an adenosine infusion was started 4 minutes after the first injection of 18F-Flurpiridaz and followed either 3 or 6 minutes later by a second radiotracer injection. In two pigs, microsphere flow measurements were made at rest and during stress. Dynamic images were reoriented into the short axis view, and regions of interest (ROIs) for the 17 myocardial segments were defined in bull's eye fashion. PET data were fitted with MGH2, a kinetic model with time varying kinetic parameters, in which blood flow changes abruptly with the introduction of adenosine. Rest and stress myocardial blood flow (MBF) were estimated simultaneously. RESULTS The first 12-14 minutes of rest-stress PET data were fitted in detail by the MGH2 model, yielding MBF measurement with a mean precision of 0.035 ml/min/cc. Mean myocardial blood flow across pigs was 0.61 ± 0.11 mL/min/cc at rest and 1.06 ± 0.19 mL/min/cc at stress in healthy pigs and 0.36 ± 0.20 mL/min/cc at rest and 0.62 ± 0.24 mL/min/cc at stress in the ischemic area. Good agreement was obtained with microsphere flow measurement (slope = 1.061 ± 0.017, intercept = 0.051 ± 0.017, mean difference 0.096 ± 0.18 ml/min/cc). CONCLUSION Accurate rest and stress blood flow estimation can be obtained in less than 15 min of PET acquisition. The method is practical and easy to implement suggesting the possibility of clinical translation.
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Affiliation(s)
- Nicolas J Guehl
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Marc D Normandin
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Dustin W Wooten
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Guy Rozen
- Cardiac Arrhythmia Service, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, 02114, USA
| | - Arkadiusk Sitek
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Jeremy Ruskin
- Cardiac Arrhythmia Service, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, 02114, USA
| | - Timothy M Shoup
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Leon M Ptaszek
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
- Cardiac Arrhythmia Service, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, 02114, USA
| | - Georges El Fakhri
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Nathaniel M Alpert
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
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Zhang JL, Morey AM, Kadrmas DJ. Application of separable parameter space techniques to multi-tracer PET compartment modeling. Phys Med Biol 2016; 61:1238-58. [PMID: 26788888 PMCID: PMC4765365 DOI: 10.1088/0031-9155/61/3/1238] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Multi-tracer positron emission tomography (PET) can image two or more tracers in a single scan, characterizing multiple aspects of biological functions to provide new insights into many diseases. The technique uses dynamic imaging, resulting in time-activity curves that contain contributions from each tracer present. The process of separating and recovering separate images and/or imaging measures for each tracer requires the application of kinetic constraints, which are most commonly applied by fitting parallel compartment models for all tracers. Such multi-tracer compartment modeling presents challenging nonlinear fits in multiple dimensions. This work extends separable parameter space kinetic modeling techniques, previously developed for fitting single-tracer compartment models, to fitting multi-tracer compartment models. The multi-tracer compartment model solution equations were reformulated to maximally separate the linear and nonlinear aspects of the fitting problem, and separable least-squares techniques were applied to effectively reduce the dimensionality of the nonlinear fit. The benefits of the approach are then explored through a number of illustrative examples, including characterization of separable parameter space multi-tracer objective functions and demonstration of exhaustive search fits which guarantee the true global minimum to within arbitrary search precision. Iterative gradient-descent algorithms using Levenberg-Marquardt were also tested, demonstrating improved fitting speed and robustness as compared to corresponding fits using conventional model formulations. The proposed technique overcomes many of the challenges in fitting simultaneous multi-tracer PET compartment models.
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Affiliation(s)
- Jeff L Zhang
- Utah Center for Advanced Imaging Research (UCAIR), Department of Radiology, University of Utah, 729 Arapeen Dr., Salt Lake City, UT 84108-1218, USA
| | - A Michael Morey
- Utah Center for Advanced Imaging Research (UCAIR), Department of Radiology, University of Utah, 729 Arapeen Dr., Salt Lake City, UT 84108-1218, USA
| | - Dan J Kadrmas
- Utah Center for Advanced Imaging Research (UCAIR), Department of Radiology, University of Utah, 729 Arapeen Dr., Salt Lake City, UT 84108-1218, USA
- MultiFunctional Imaging, 615 Arapeen Dr. Suite 310, Salt Lake City, UT 84108-1254, USA
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El Fakhri G, Trott CM, Sitek A, Bonab A, Alpert NM. Dual-tracer PET using generalized factor analysis of dynamic sequences. Mol Imaging Biol 2014; 15:666-74. [PMID: 23636489 DOI: 10.1007/s11307-013-0631-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE With single-photon emission computed tomography, simultaneous imaging of two physiological processes relies on discrimination of the energy of the emitted gamma rays, whereas the application of dual-tracer imaging to positron emission tomography (PET) imaging has been limited by the characteristic 511-keV emissions. PROCEDURES To address this limitation, we developed a novel approach based on generalized factor analysis of dynamic sequences (GFADS) that exploits spatio-temporal differences between radiotracers and applied it to near-simultaneous imaging of 2-deoxy-2-[(18)F]fluoro-D-glucose (FDG) (brain metabolism) and (11)C-raclopride (D2) with simulated human data and experimental rhesus monkey data. We show theoretically and verify by simulation and measurement that GFADS can separate FDG and raclopride measurements that are made nearly simultaneously. RESULTS The theoretical development shows that GFADS can decompose the studies at several levels: (1) It decomposes the FDG and raclopride study so that they can be analyzed as though they were obtained separately. (2) If additional physiologic/anatomic constraints can be imposed, further decomposition is possible. (3) For the example of raclopride, specific and nonspecific binding can be determined on a pixel-by-pixel basis. We found good agreement between the estimated GFADS factors and the simulated ground truth time activity curves (TACs), and between the GFADS factor images and the corresponding ground truth activity distributions with errors less than 7.3 ± 1.3 %. Biases in estimation of specific D2 binding and relative metabolism activity were within 5.9 ± 3.6 % compared to the ground truth values. We also evaluated our approach in simultaneous dual-isotope brain PET studies in a rhesus monkey and obtained accuracy of better than 6 % in a mid-striatal volume, for striatal activity estimation. CONCLUSIONS Dynamic image sequences acquired following near-simultaneous injection of two PET radiopharmaceuticals can be separated into components based on the differences in the kinetics, provided their kinetic behaviors are distinct.
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Affiliation(s)
- Georges El Fakhri
- Center for Advanced Medical Imaging Sciences NMMI, Radiology Department, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA,
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15
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Rahmim A, Tahari AK, Schindler TH. Towards Quantitative Myocardial Perfusion PET in the Clinic. J Am Coll Radiol 2014; 11:429-32. [DOI: 10.1016/j.jacr.2013.12.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2013] [Accepted: 12/24/2013] [Indexed: 12/14/2022]
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16
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Verhaeghe J, Reader AJ. Accelerated PET water activation acquisition with signal separation methodology. Med Phys 2013; 40:031909. [DOI: 10.1118/1.4789483] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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17
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Abstract
Rapid multi-tracer PET aims to image two or more tracers in a single scan, simultaneously characterizing multiple aspects of physiology and function without the need for repeat imaging visits. Using dynamic imaging with staggered injections, constraints on the kinetic behavior of each tracer are applied to recover individual-tracer measures from the multi-tracer PET signal. The ability to rapidly and reliably image both (18)F-fluorodeoxyglucose (FDG) and (18)F-fluorothymidine (FLT) would provide complementary measures of tumor metabolism and proliferative activity, with important applications in guiding oncologic treatment decisions and assessing response. However, this tracer combination presents one of the most challenging dual-tracer signal-separation problems--both tracers have the same radioactive half-life, and the injection delay is short relative to the half-life and tracer kinetics. This work investigates techniques for single-scan dual-tracer FLT+FDG PET tumor imaging, characterizing the performance of recovering static and dynamic imaging measures for each tracer from dual-tracer datasets. Simulation studies were performed to characterize dual-tracer signal-separation performance for imaging protocols with both injection orders and injection delays of 10-60 min. Better performance was observed when FLT was administered first, and longer delays before administration of FDG provided more robust signal-separation and recovery of the single-tracer imaging measures. An injection delay of 30 min led to good recovery (R > 0.96) of static image values (e.g. SUV), K(net), and K(1) as compared to values from separate, single-tracer time-activity curves. Recovery of higher order rate parameters (k(2), k(3)) was less robust, indicating that information regarding these parameters was harder to recover in the presence of statistical noise and dual-tracer effects. Performance of the dual-tracer FLT(0 min)+FDG(32 min) technique was further evaluated using PET/CT imaging studies in five patients with primary brain tumors where the data from separate scans of each tracer were combined to synthesize dual-tracer scans with known single-tracer components; results demonstrated similar dual-tracer signal recovery performance. We conclude that rapid dual-tracer FLT+FDG tumor imaging is feasible and can provide quantitative tumor imaging measures comparable to those from conventional separate-scan imaging.
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Affiliation(s)
- Dan J Kadrmas
- Utah Center for Advanced Imaging Research, University of Utah, Salt Lake City, UT, USA.
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Alpert N, Dean Fang YH, El Fakhri G. Single-scan rest∕stress imaging (18)F-labeled flow tracers. Med Phys 2013; 39:6609-20. [PMID: 23127055 DOI: 10.1118/1.4754585] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE The authors report a novel measurement strategy to obtain both rest and stress blood flow during a single, relatively short, scan session. METHODS Measurement of rest-stress myocardial blood flow with long-lived tracers usually requires separate scan sessions to remove the confounding effects of residual radioactivity concentration in the blood and tissue. The innovation of this method is to treat the rest-stress scan as a single entity in which the flow parameters change due to pharmacological challenge. With this approach the fate of a tracer molecule is naturally accounted for, no matter if it was introduced during the rest or stress phase of the study. Two new dual-injection kinetic models are considered that represent the response to pharmacological stress as a transitional or transient increase of myocardial blood flow. The authors present the theory of the method followed by the specific application of the theory to (18)F-Flurpiridaz, a new myocardial flow-imaging agent. RESULTS Myocardial blood flow was accurately and precisely estimated from a single-scan rest∕stress study for the long half-lived tracer (18)F-Flurpiridaz. By accounting for the time-dependence of the kinetic parameters, the proposed models achieved good accuracy and precision (5%) under different vasodilators and different ischemic states. CONCLUSIONS Detailed simulations predict that accurate and precise rest-stress blood flow measurements can be obtained in 20-30 min.
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Affiliation(s)
- Nathaniel Alpert
- Department of Radiology, Massachusetts General Hospital, Boston, MA 02114, USA
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19
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Verhaeghe J, Reader AJ. Simultaneous water activation and glucose metabolic rate imaging with PET. Phys Med Biol 2013; 58:393-411. [DOI: 10.1088/0031-9155/58/3/393] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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20
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Fakhri GE. Ready for prime time? Dual tracer PET and SPECT imaging. AMERICAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING 2012; 2:415-417. [PMID: 23145358 PMCID: PMC3484417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 10/14/2012] [Accepted: 10/18/2012] [Indexed: 06/01/2023]
Abstract
Dual isotope single photon emission computed tomography (SPECT) and dual tracer positron emission tomography (PET) imaging have great potential in clinical and molecular applications in the pediatric as well as the adult populations in many areas of brain, cardiac, and oncologic imaging as it allows the exploration of different physiological and molecular functions (e.g., perfusion, neurotransmission, metabolism, apoptosis, angiogenesis) under the same physiological and physical conditions. This is crucial when the physiological functions studied depend on each other (e.g., perfusion and metabolism) hence requiring simultaneous assessment under identical conditions, and can reduce greatly the quantitation errors associated with physical factors that can change between acquisitions (e.g., human subject or animal motion, change in the attenuation map as a function of time) as is detailed in this editorial. The clinical potential of simultaneous dual isotope SPECT, dual tracer PET and dual SPECT/PET imaging are explored and summarized. In this issue of AJNMMI (http://www.ajnmmi.us), Chapman et al. explore the feasibility of simultaneous and sequential SPECT/PET imaging and conclude that down-scatter and crosstalk from 511 keV photons preclude obtaining useful SPECT information in the presence of PET radiotracers. They report on an alternative strategy that consists of performing sequential SPECT and PET studies in hybrid microPET/SPECT/CT scanners, now widely available for molecular imaging. They validate their approach in a phantom consisting of a 96-well plate with variable (99m)Tc and (18)F concentrations and illustrate the utility of such approaches in two sequential SPECT-PET/CT studies that include (99m)Tc-MAA/(18)F-NaF and (99m)Tc-Pentetate/(18)F-NaF. These approaches will need to be proven reproducible, accurate and robust to variations in the experimental conditions before they can be accepted by the molecular imaging community and be implemented in routine molecular microPET and microSPECT explorations. Although currently not accepted as standard procedures in the molecular imaging community, such approaches have the potential to open the way to new SPECT/PET explorations that allow studying molecular mechanisms and pathways in the living animal under similar physiological conditions. Although still premature for the clinical setting, these approaches can be extended to clinical research once proven accurate and precise in vivo in small and large animal models.
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Affiliation(s)
- Georges El Fakhri
- Center for Advanced Radiological Sciences, Harvard Medical SchoolBoston, MA
- Division of Nuclear Medicine & Molecular Imaging, Radiology, Massachusetts General HospitalBoston, MA
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21
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Utility of dynamic perfusion PET using ¹³N-ammonia in diagnosis of asymptomatic recurrence of fibrosarcoma. Clin Nucl Med 2011; 36:150-1. [PMID: 21220986 DOI: 10.1097/rlu.0b013e318203be6c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Fibrosarcoma is a rare tumor involving the musculoskeletal system. Anatomic imaging modalities like CT and MRI are useful in characterization and staging of the tumor. FDG PET has variable sensitivity in evaluation of these tumors. Alternative tracers like FLT have been tried. It is a well-known fact that sarcomas are highly vascular. We report the utility of dynamic perfusion PET imaging using N13-ammonia in diagnosing a case of asymptomatic recurrence of fibrosarcoma in a 45-year-old patient. Despite very faint FDG avidity, ammonia perfusion imaging showed hypervascularity and allowed identification of the asymptomatic early recurrence.
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Al-Mallah MH, Sitek A, Moore SC, Di Carli M, Dorbala S. Assessment of myocardial perfusion and function with PET and PET/CT. J Nucl Cardiol 2010; 17:498-513. [PMID: 20379862 PMCID: PMC2871404 DOI: 10.1007/s12350-010-9223-5] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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23
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Black NF, McJames S, Kadrmas DJ. Rapid Multi-Tracer PET Tumor Imaging With F-FDG and Secondary Shorter-Lived Tracers. IEEE TRANSACTIONS ON NUCLEAR SCIENCE 2009; 56:2750-2758. [PMID: 20046800 PMCID: PMC2799294 DOI: 10.1109/tns.2009.2026417] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Rapid multi-tracer PET, where two to three PET tracers are rapidly scanned with staggered injections, can recover certain imaging measures for each tracer based on differences in tracer kinetics and decay. We previously showed that single-tracer imaging measures can be recovered to a certain extent from rapid dual-tracer (62)Cu - PTSM (blood flow) + (62)Cu - ATSM (hypoxia) tumor imaging. In this work, the feasibility of rapidly imaging (18)F-FDG plus one or two of these shorter-lived secondary tracers was evaluated in the same tumor model. Dynamic PET imaging was performed in four dogs with pre-existing tumors, and the raw scan data was combined to emulate 60 minute long dual- and triple-tracer scans, using the single-tracer scans as gold standards. The multi-tracer data were processed for static (SUV) and kinetic (K(1), K(net)) endpoints for each tracer, followed by linear regression analysis of multi-tracer versus single-tracer results. Static and quantitative dynamic imaging measures of FDG were both accurately recovered from the multi-tracer scans, closely matching the single-tracer FDG standards (R > 0.99). Quantitative blood flow information, as measured by PTSM K(1) and SUV, was also accurately recovered from the multi-tracer scans (R = 0.97). Recovery of ATSM kinetic parameters proved more difficult, though the ATSM SUV was reasonably well recovered (R = 0.92). We conclude that certain additional information from one to two shorter-lived PET tracers may be measured in a rapid multi-tracer scan alongside FDG without compromising the assessment of glucose metabolism. Such additional and complementary information has the potential to improve tumor characterization in vivo, warranting further investigation of rapid multi-tracer techniques.
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Affiliation(s)
- Noel F. Black
- Utah Center for Advanced Imaging Research, University of Utah, Salt Lake City, UT 84108-1218 USA
| | - Scott McJames
- Department of Anesthesiology, University of Utah Health Sciences Center, Salt Lake City, UT 84132-2304 USA
| | - Dan J. Kadrmas
- Utah Center for Advanced Imaging Research, University of Utah, Salt Lake City, UT 84108-1218 USA
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Joshi AD, Koeppe RA, Fessler JA, Kilbourn MR. Signal separation and parameter estimation in noninvasive dual-tracer PET scans using reference-region approaches. J Cereb Blood Flow Metab 2009; 29:1346-57. [PMID: 19401708 DOI: 10.1038/jcbfm.2009.53] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
This is the first study to report results from a noninvasive dual-tracer positron emission tomography (PET) in humans not requiring arterial sampling, in which two radiotracers were injected closely in time within the same scan. These studies yield near simultaneous information on two different neuropharmacological systems, providing better characterization of a subject's neurologic condition. The noninvasive dual-tracer approach described in this study is based on the primary assumption that an appropriate bolus plus constant infusion protocol brings the reference tissue of the first radiotracer to steady state before injection of the second tracer. Two methods for separation of time-activity curves (TACs) and parameter estimation were investigated, namely (1) an extrapolation method, in which TACs of the first tracer were extrapolated over total scan duration followed by subtraction from dual-tracer TACs and (2) a simultaneous fitting method, in which reference-region models for both tracers were fitted simultaneously to dual-tracer TACs. Combinations of two reversible tracers ([(11)C]flumazenil and [(11)C]dihydrotetrabenazine) or one reversible and one irreversible tracer ([(11)C]N-methylpiperidinyl propionate) were used. After the dual-tracer scan, a single-tracer (ST) scan using one of the tracers was obtained for comparison of the dual-tracer results. Both approaches provided parameter estimates with intersubject regions-of-interest means typically within 10% of those obtained from ST scans without an appreciable increase in variance.
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Affiliation(s)
- Aniket D Joshi
- Division of Nuclear Medicine, Department of Radiology, University of Michigan, Ann Arbor, Michigan, USA
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Abstract
Multimodality small-animal molecular imaging has become increasingly important as transgenic and knockout mice are produced to model human diseases. With the ever-increasing number and importance of human disease models, particularly in rodents (mice and rats), the ability of high-resolution multimodality molecular imaging instrumentation to contribute unique information is becoming more common and necessary. Multimodality imaging with high spatial resolution and good sensitivity, which combines modalities and records sequentially or simultaneously complementary information, offers many advantages in certain research experiments. This article discusses the current trends and new horizons in preclinical multimodality imaging in-vivo and its role in biomedical research.
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Affiliation(s)
- David B Stout
- Crump Institute for Molecular Imaging, Department of Molecular and Medical Pharmacology, The David Geffen School of Medicine at UCLA, 570 Westwood Plaza, CNSI Building, Room 2151, Los Angeles, CA 90095, USA
| | - Habib Zaidi
- Division of Nuclear Medicine, Geneva University Hospital, CH-1211 Geneva, Switzerland.
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Navigating beyond the 6th dimension: a challenge in the era of multi-parametric molecular imaging. Eur J Nucl Med Mol Imaging 2009; 36:1025-8. [DOI: 10.1007/s00259-009-1095-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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27
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Gao F, Liu H, Jian Y, Shi P. Dynamic Dual-Tracer PET Reconstruction. LECTURE NOTES IN COMPUTER SCIENCE 2009; 21:38-49. [DOI: 10.1007/978-3-642-02498-6_4] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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28
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Pack NA, DiBella EVR, Rust TC, Kadrmas DJ, McGann CJ, Butterfield R, Christian PE, Hoffman JM. Estimating myocardial perfusion from dynamic contrast-enhanced CMR with a model-independent deconvolution method. J Cardiovasc Magn Reson 2008; 10:52. [PMID: 19014509 PMCID: PMC2596132 DOI: 10.1186/1532-429x-10-52] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2008] [Accepted: 11/12/2008] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Model-independent analysis with B-spline regularization has been used to quantify myocardial blood flow (perfusion) in dynamic contrast-enhanced cardiovascular magnetic resonance (CMR) studies. However, the model-independent approach has not been extensively evaluated to determine how the contrast-to-noise ratio between blood and tissue enhancement affects estimates of myocardial perfusion and the degree to which the regularization is dependent on the noise in the measured enhancement data. We investigated these questions with a model-independent analysis method that uses iterative minimization and a temporal smoothness regularizer. Perfusion estimates using this method were compared to results from dynamic 13N-ammonia PET. RESULTS An iterative model-independent analysis method was developed and tested to estimate regional and pixelwise myocardial perfusion in five normal subjects imaged with a saturation recovery turboFLASH sequence at 3 T CMR. Estimates of myocardial perfusion using model-independent analysis are dependent on the choice of the regularization weight parameter, which increases nonlinearly to handle large decreases in the contrast-to-noise ratio of the measured tissue enhancement data. Quantitative perfusion estimates in five subjects imaged with 3 T CMR were 1.1 +/- 0.8 ml/min/g at rest and 3.1 +/- 1.7 ml/min/g at adenosine stress. The perfusion estimates correlated with dynamic 13N-ammonia PET (y = 0.90x + 0.24, r = 0.85) and were similar to results from other validated CMR studies. CONCLUSION This work shows that a model-independent analysis method that uses iterative minimization and temporal regularization can be used to quantify myocardial perfusion with dynamic contrast-enhanced perfusion CMR. Results from this method are robust to choices in the regularization weight parameter over relatively large ranges in the contrast-to-noise ratio of the tissue enhancement data.
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Affiliation(s)
- Nathan A Pack
- Department of Bioengineering, University of Utah, Salt Lake City, Salt Lake County, Utah, USA
- Utah Center for Advanced Imaging Research, Department of Radiology, University of Utah, Salt Lake City, Salt Lake County, Utah, USA
| | - Edward VR DiBella
- Department of Bioengineering, University of Utah, Salt Lake City, Salt Lake County, Utah, USA
- Utah Center for Advanced Imaging Research, Department of Radiology, University of Utah, Salt Lake City, Salt Lake County, Utah, USA
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Salt Lake County, Utah, USA
| | - Thomas C Rust
- Utah Center for Advanced Imaging Research, Department of Radiology, University of Utah, Salt Lake City, Salt Lake County, Utah, USA
| | - Dan J Kadrmas
- Department of Bioengineering, University of Utah, Salt Lake City, Salt Lake County, Utah, USA
- Utah Center for Advanced Imaging Research, Department of Radiology, University of Utah, Salt Lake City, Salt Lake County, Utah, USA
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Salt Lake County, Utah, USA
| | - Christopher J McGann
- Utah Center for Advanced Imaging Research, Department of Radiology, University of Utah, Salt Lake City, Salt Lake County, Utah, USA
| | - Regan Butterfield
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Salt Lake County, Utah, USA
| | - Paul E Christian
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Salt Lake County, Utah, USA
| | - John M Hoffman
- Utah Center for Advanced Imaging Research, Department of Radiology, University of Utah, Salt Lake City, Salt Lake County, Utah, USA
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Salt Lake County, Utah, USA
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Pack N, DiBella E, McGann C, Rust T, Kadrmas D, Butterfield R, Christian P, Hoffman JM. 151 myocardial blood flow estimation using a model-independent deconvolution method at 3 T MRI: comparison to N-ammonia PET. J Cardiovasc Magn Reson 2008. [DOI: 10.1186/1532-429x-10-s1-a52] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Black NF, McJames S, Rust TC, Kadrmas DJ. Evaluation of rapid dual-tracer (62)Cu-PTSM + (62)Cu-ATSM PET in dogs with spontaneously occurring tumors. Phys Med Biol 2008; 53:217-32. [PMID: 18182698 PMCID: PMC3746544 DOI: 10.1088/0031-9155/53/1/015] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We are developing methods for imaging multiple PET tracers in a single scan with staggered injections, where imaging measures for each tracer are separated and recovered using differences in tracer kinetics and radioactive decay. In this work, signal separation performance for rapid dual-tracer (62)Cu-PTSM (blood flow) + (62)Cu-ATSM (hypoxia) tumor imaging was evaluated in a large animal model. Four dogs with pre-existing tumors received a series of dynamic PET scans with (62)Cu-PTSM and (62)Cu-ATSM, permitting evaluation of a rapid dual-tracer protocol designed by previous simulation work. Several imaging measures were computed from the dual-tracer data and compared with those from separate, single-tracer imaging. Static imaging measures (e.g. SUV) for each tracer were accurately recovered from dual-tracer data. The wash-in (k(1)) and wash-out (k(2)) rate parameters for both tracers were likewise well recovered (r = 0.87-0.99), but k(3) was not accurately recovered for PTSM (r = 0.19) and moderately well recovered for ATSM (r = 0.70). Some degree of bias was noted, however, which may potentially be overcome through further refinement of the signal separation algorithms. This work demonstrates that complementary information regarding tumor blood flow and hypoxia can be acquired by a single dual-tracer PET scan, and also that the signal separation procedure works effectively for real physiologic data with realistic levels of kinetic model mismatch. Rapid multi-tracer PET has the potential to improve tumor assessment for image-guide therapy and monitoring, and further investigation with these and other tracers is warranted.
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Affiliation(s)
- Noel F Black
- Utah Center of Advanced Imaging Research, University of Utah, 729 Arapeen Drive, Salt Lake City, UT 84108-1218, USA
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Kadrmas DJ, Rust TC, Hoffman JM. Characterization of Multiple Aspects of Tumor Physiology by Multitracer Positron Emission Tomography. Cancer Imaging 2008. [DOI: 10.1016/b978-012374212-4.50084-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
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33
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Champion C, Le Loirec C. Positron follow-up in liquid water: II. Spatial and energetic study for the most important radioisotopes used in PET. Phys Med Biol 2007; 52:6605-25. [DOI: 10.1088/0031-9155/52/22/004] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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