1
|
Fettahoglu A, Zhao M, Khalighi M, Vossler H, Jovin M, Davidzon G, Zeineh M, Boada F, Mormino E, Henderson VW, Moseley M, Chen KT, Zaharchuk G. Early-Frame [ 18F]Florbetaben PET/MRI for Cerebral Blood Flow Quantification in Patients with Cognitive Impairment: Comparison to an [ 15O]Water Gold Standard. J Nucl Med 2024; 65:306-312. [PMID: 38071587 PMCID: PMC10858379 DOI: 10.2967/jnumed.123.266273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2023] [Revised: 10/24/2023] [Indexed: 02/03/2024] Open
Abstract
Cerebral blood flow (CBF) may be estimated from early-frame PET imaging of lipophilic tracers, such as amyloid agents, enabling measurement of this important biomarker in participants with dementia and memory decline. Although previous methods could map relative CBF, quantitative measurement in absolute units (mL/100 g/min) remained challenging and has not been evaluated against the gold standard method of [15O]water PET. The purpose of this study was to develop and validate a minimally invasive quantitative CBF imaging method combining early [18F]florbetaben (eFBB) with phase-contrast MRI using simultaneous PET/MRI. Methods: Twenty participants (11 men and 9 women; 8 cognitively normal, 9 with mild cognitive impairment, and 3 with dementia; 10 β-amyloid negative and 10 β-amyloid positive; 69 ± 9 y old) underwent [15O]water PET, phase-contract MRI, and eFBB imaging in a single session on a 3-T PET/MRI scanner. Quantitative CBF images were created from the first 2 min of brain activity after [18F]florbetaben injection combined with phase-contrast MRI measurement of total brain blood flow. These maps were compared with [15O]water CBF using concordance correlation (CC) and Bland-Altman statistics for gray matter, white matter, and individual regions derived from the automated anatomic labeling (AAL) atlas. Results: The 2 methods showed similar results in gray matter ([15O]water, 55.2 ± 14.7 mL/100 g/min; eFBB, 55.9 ± 14.2 mL/100 g/min; difference, 0.7 ± 2.4 mL/100 g/min; P = 0.2) and white matter ([15O]water, 21.4 ± 5.6 mL/100 g/min; eFBB, 21.2 ± 5.3 mL/100 g/min; difference, -0.2 ± 1.0 mL/100 g/min; P = 0.4). The intrasubject CC for AAL-derived regions was high (0.91 ± 0.04). Intersubject CC in different AAL-derived regions was similarly high, ranging from 0.86 for midfrontal regions to 0.98 for temporal regions. There were no significant differences in performance between the methods in the amyloid-positive and amyloid-negative groups as well as participants with different cognitive statuses. Conclusion: We conclude that eFBB PET/MRI can provide robust CBF measurements, highlighting the capability of simultaneous PET/MRI to provide measurements of both CBF and amyloid burden in a single imaging session in participants with memory disorders.
Collapse
Affiliation(s)
- Ates Fettahoglu
- Department of Radiology, Stanford University, Stanford, California
- Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, Connecticut
| | - Moss Zhao
- Department of Radiology, Stanford University, Stanford, California
- Stanford Cardiovascular Institute, Stanford University, Stanford, California
| | - Mehdi Khalighi
- Department of Radiology, Stanford University, Stanford, California
| | - Hillary Vossler
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, California; and
| | - Maria Jovin
- Department of Radiology, Stanford University, Stanford, California
| | - Guido Davidzon
- Department of Radiology, Stanford University, Stanford, California
| | - Michael Zeineh
- Department of Radiology, Stanford University, Stanford, California
| | - Fernando Boada
- Department of Radiology, Stanford University, Stanford, California
| | - Elizabeth Mormino
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, California; and
| | - Victor W Henderson
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, California; and
| | - Michael Moseley
- Department of Radiology, Stanford University, Stanford, California
| | - Kevin T Chen
- Department of Biomedical Engineering, National Taiwan University, Taipei, Taiwan
| | - Greg Zaharchuk
- Department of Radiology, Stanford University, Stanford, California
| |
Collapse
|
2
|
Chen KT, Tesfay R, Koran MEI, Ouyang J, Shams S, Young CB, Davidzon G, Liang T, Khalighi M, Mormino E, Zaharchuk G. Generative Adversarial Network-Enhanced Ultra-Low-Dose [ 18F]-PI-2620 τ PET/MRI in Aging and Neurodegenerative Populations. AJNR Am J Neuroradiol 2023; 44:1012-1019. [PMID: 37591771 PMCID: PMC10494955 DOI: 10.3174/ajnr.a7961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Accepted: 07/11/2023] [Indexed: 08/19/2023]
Abstract
BACKGROUND AND PURPOSE With the utility of hybrid τ PET/MR imaging in the screening, diagnosis, and follow-up of individuals with neurodegenerative diseases, we investigated whether deep learning techniques can be used in enhancing ultra-low-dose [18F]-PI-2620 τ PET/MR images to produce diagnostic-quality images. MATERIALS AND METHODS Forty-four healthy aging participants and patients with neurodegenerative diseases were recruited for this study, and [18F]-PI-2620 τ PET/MR data were simultaneously acquired. A generative adversarial network was trained to enhance ultra-low-dose τ images, which were reconstructed from a random sampling of 1/20 (approximately 5% of original count level) of the original full-dose data. MR images were also used as additional input channels. Region-based analyses as well as a reader study were conducted to assess the image quality of the enhanced images compared with their full-dose counterparts. RESULTS The enhanced ultra-low-dose τ images showed apparent noise reduction compared with the ultra-low-dose images. The regional standard uptake value ratios showed that while, in general, there is an underestimation for both image types, especially in regions with higher uptake, when focusing on the healthy-but-amyloid-positive population (with relatively lower τ uptake), this bias was reduced in the enhanced ultra-low-dose images. The radiotracer uptake patterns in the enhanced images were read accurately compared with their full-dose counterparts. CONCLUSIONS The clinical readings of deep learning-enhanced ultra-low-dose τ PET images were consistent with those performed with full-dose imaging, suggesting the possibility of reducing the dose and enabling more frequent examinations for dementia monitoring.
Collapse
Affiliation(s)
- K T Chen
- From the Department of Biomedical Engineering (K.T.C.), National Taiwan University, Taipei, Taiwan
- Department of Radiology (K.T.C., M.E.I.K., J.O., S.S., G.D., T.L., M.K., G.Z.), Stanford University, Stanford, California
| | - R Tesfay
- Meharry Medical College (R.T.), Nashville, Tennessee
| | - M E I Koran
- Department of Radiology (K.T.C., M.E.I.K., J.O., S.S., G.D., T.L., M.K., G.Z.), Stanford University, Stanford, California
| | - J Ouyang
- Department of Radiology (K.T.C., M.E.I.K., J.O., S.S., G.D., T.L., M.K., G.Z.), Stanford University, Stanford, California
| | - S Shams
- Department of Radiology (K.T.C., M.E.I.K., J.O., S.S., G.D., T.L., M.K., G.Z.), Stanford University, Stanford, California
| | - C B Young
- Department of Neurology and Neurological Sciences (C.B.Y., E.M.), Stanford University, Stanford, California
| | - G Davidzon
- Department of Radiology (K.T.C., M.E.I.K., J.O., S.S., G.D., T.L., M.K., G.Z.), Stanford University, Stanford, California
| | - T Liang
- Department of Radiology (K.T.C., M.E.I.K., J.O., S.S., G.D., T.L., M.K., G.Z.), Stanford University, Stanford, California
| | - M Khalighi
- Department of Radiology (K.T.C., M.E.I.K., J.O., S.S., G.D., T.L., M.K., G.Z.), Stanford University, Stanford, California
| | - E Mormino
- Department of Neurology and Neurological Sciences (C.B.Y., E.M.), Stanford University, Stanford, California
| | - G Zaharchuk
- Department of Radiology (K.T.C., M.E.I.K., J.O., S.S., G.D., T.L., M.K., G.Z.), Stanford University, Stanford, California
| |
Collapse
|
3
|
Yoon JH, Zhang Z, Mormino E, Davidzon G, Minzenberg MJ, Ballon J, Kalinowski A, Hardy K, Naganawa M, Carson RE, Khalighi M, Park JH, Levinson DF, Chin FT. Reductions in synaptic marker SV2A in early-course Schizophrenia. J Psychiatr Res 2023; 161:213-217. [PMID: 36934603 DOI: 10.1016/j.jpsychires.2023.02.026] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 02/14/2023] [Accepted: 02/22/2023] [Indexed: 03/21/2023]
Abstract
Excess synaptic pruning during neurodevelopment has emerged as one of the leading hypotheses on the causal mechanism for schizophrenia. It proposes that excess synaptic elimination occurs during development before the formal onset of illness. Accordingly, synaptic deficits may be observable at all stages of illnesses, including in the early phases. The availability of [11C]UCB-J, the first-in-human in vivo synaptic marker, represents an opportunity for testing this hypothesis with a relatively high level of precision. The first two published [11C]UCB-J schizophrenia studies have documented significant, widespread reductions in binding in chronic patients. The present study tested the hypothesis that reductions are present in early-course patients. 18 subjects completed [11C]UCB-J PET scans, (nine with schizophrenia, average duration of illness of 3.36 years, and nine demographically-matched healthy individuals). We compared binding levels, quantified as non-displaceable specific binding (BPND), in a set of a priori-specified brain regions of interest (ROIs). Eight ROIs (left and right hippocampus, right superior temporal and Heschl's gyrus, left and right putamen, and right caudal and rostral middle frontal gyrus) showed large reductions meeting Bonferroni corrected significant levels, p < 0.0036. Exploratory, atlas-wide analyses confirmed widespread reductions in schizophrenia. We also observed significant positive correlations between binding levels and cognitive performance and a negative correlation with the severity of delusions. These results largely replicate findings from chronic patients, indicating that extensive [11C]UCB-J binding deficits are reliable and reproducible. Moreover, these results add to the growing evidence that excess synaptic pruning is a major disease mechanism for schizophrenia.
Collapse
Affiliation(s)
- Jong H Yoon
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine and VA Palo Alto Health Care System, Palo Alto, CA, USA.
| | - Zhener Zhang
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine and VA Palo Alto Health Care System, Palo Alto, CA, USA
| | - Elizabeth Mormino
- Department of Neurology, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Guido Davidzon
- Department of Radiology - Nuclear Medicine, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Michael J Minzenberg
- Department of Psychiatry, University of California Davis School of Medicine, Sacramento, CA, USA
| | - Jacob Ballon
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Agnieszka Kalinowski
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Kate Hardy
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Mika Naganawa
- Department of Radiology, Yale University, New Haven, CT, USA
| | | | - Mehdi Khalighi
- Department of Radiology, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Jun Hyung Park
- Department of Radiology, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Douglas F Levinson
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Frederick T Chin
- Department of Radiology, Stanford University School of Medicine, Palo Alto, CA, USA
| |
Collapse
|
4
|
Zhao M, Chen K, Khalighi M, Mormino EC, Zaharchuk G. Dual‐tracer assessment of CBF and early amyloid uptake of Alzheimer’s disease using 15O‐water and amyloid PET. Alzheimers Dement 2022. [DOI: 10.1002/alz.066700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
| | - Kevin Chen
- National University of Taiwan Taipei Taiwan
| | | | | | | |
Collapse
|
5
|
Chen K, Tesfay R, Koran ME, Ouyang J, Shams S, Liang T, Khalighi M, Mormino EC, Zaharchuk G. Generative Adversarial Network‐Enhanced Ultra‐low‐dose [18F]‐PI‐2620 Tau PET/MR Imaging. Alzheimers Dement 2022. [DOI: 10.1002/alz.062271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Kevin Chen
- National Taiwan University Taipei City Taiwan
- Stanford University Stanford CA USA
| | | | | | | | | | | | | | | | | |
Collapse
|
6
|
Chen K, Adeyeri O, Toueg T, Zeineh M, Mormino E, Khalighi M, Zaharchuk G. Investigating Simultaneity for Deep Learning-Enhanced Actual Ultra-Low-Dose Amyloid PET/MR Imaging. AJNR Am J Neuroradiol 2022; 43:354-360. [PMID: 35086799 PMCID: PMC8910791 DOI: 10.3174/ajnr.a7410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Accepted: 11/15/2021] [Indexed: 01/27/2023]
Abstract
BACKGROUND AND PURPOSE Diagnostic-quality amyloid PET images can be created with deep learning using actual ultra-low-dose PET images and simultaneous structural MR imaging. Here, we investigated whether simultaneity is required; if not, MR imaging-assisted ultra-low-dose PET imaging could be performed with separate PET/CT and MR imaging acquisitions. MATERIALS AND METHODS We recruited 48 participants: Thirty-two (20 women; mean, 67.7 [SD, 7.9] years) were used for pretraining; 328 (SD, 32) MBq of [18F] florbetaben was injected. Sixteen participants (6 women; mean, 71.4 [SD. 8.7] years of age) were scanned in 2 sessions, with 6.5 (SD, 3.8) and 300 (SD, 14) MBq of [18F] florbetaben injected, respectively. Structural MR imaging was acquired simultaneously with PET (90-110 minutes postinjection) on integrated PET/MR imaging in 2 sessions. Multiple U-Net-based deep networks were trained to create diagnostic PET images. For each method, training was done with the ultra-low-dose PET as input combined with MR imaging from either the ultra-low-dose session (simultaneous) or from the standard-dose PET session (nonsimultaneous). Image quality of the enhanced and ultra-low-dose PET images was evaluated using quantitative signal-processing methods, standardized uptake value ratio correlation, and clinical reads. RESULTS Qualitatively, the enhanced images resembled the standard-dose image for both simultaneous and nonsimultaneous conditions. Three quantitative metrics showed significant improvement for all networks and no differences due to simultaneity. Standardized uptake value ratio correlation was high across different image types and network training methods, and 31/32 enhanced image pairs were read similarly. CONCLUSIONS This work suggests that accurate amyloid PET images can be generated using enhanced ultra-low-dose PET and either nonsimultaneous or simultaneous MR imaging, broadening the utility of ultra-low-dose amyloid PET imaging.
Collapse
Affiliation(s)
- K.T. Chen
- From the Department of Radiology (K.T.C., M.Z., M.K., G.Z.), Stanford University, Stanford, California,Department of Biomedical Engineering (K.T.C.), National Taiwan University, Taipei, Taiwan
| | - O. Adeyeri
- Department of Computer Science (O.A.), Salem State University, Salem, Massachusetts
| | - T.N. Toueg
- Department of Neurology and Neurological Sciences (T.N.T., E.M.), Stanford University, Stanford, California
| | - M. Zeineh
- From the Department of Radiology (K.T.C., M.Z., M.K., G.Z.), Stanford University, Stanford, California
| | - E. Mormino
- Department of Neurology and Neurological Sciences (T.N.T., E.M.), Stanford University, Stanford, California
| | - M. Khalighi
- From the Department of Radiology (K.T.C., M.Z., M.K., G.Z.), Stanford University, Stanford, California
| | - G. Zaharchuk
- From the Department of Radiology (K.T.C., M.Z., M.K., G.Z.), Stanford University, Stanford, California
| |
Collapse
|
7
|
Beinat C, Patel CB, Haywood T, Murty S, Naya L, Castillo JB, Reyes ST, Phillips M, Buccino P, Shen B, Park JH, Koran MEI, Alam IS, James ML, Holley D, Halbert K, Gandhi H, He JQ, Granucci M, Johnson E, Liu DD, Uchida N, Sinha R, Chu P, Born DE, Warnock GI, Weissman I, Hayden-Gephart M, Khalighi M, Massoud TF, Iagaru A, Davidzon G, Thomas R, Nagpal S, Recht LD, Gambhir SS. A Clinical PET Imaging Tracer ([ 18F]DASA-23) to Monitor Pyruvate Kinase M2-Induced Glycolytic Reprogramming in Glioblastoma. Clin Cancer Res 2021; 27:6467-6478. [PMID: 34475101 PMCID: PMC8639752 DOI: 10.1158/1078-0432.ccr-21-0544] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 07/15/2021] [Accepted: 08/30/2021] [Indexed: 01/10/2023]
Abstract
PURPOSE Pyruvate kinase M2 (PKM2) catalyzes the final step in glycolysis, a key process of cancer metabolism. PKM2 is preferentially expressed by glioblastoma (GBM) cells with minimal expression in healthy brain. We describe the development, validation, and translation of a novel PET tracer to study PKM2 in GBM. We evaluated 1-((2-fluoro-6-[18F]fluorophenyl)sulfonyl)-4-((4-methoxyphenyl)sulfonyl)piperazine ([18F]DASA-23) in cell culture, mouse models of GBM, healthy human volunteers, and patients with GBM. EXPERIMENTAL DESIGN [18F]DASA-23 was synthesized with a molar activity of 100.47 ± 29.58 GBq/μmol and radiochemical purity >95%. We performed initial testing of [18F]DASA-23 in GBM cell culture and human GBM xenografts implanted orthotopically into mice. Next, we produced [18F]DASA-23 under FDA oversight, and evaluated it in healthy volunteers and a pilot cohort of patients with glioma. RESULTS In mouse imaging studies, [18F]DASA-23 clearly delineated the U87 GBM from surrounding healthy brain tissue and had a tumor-to-brain ratio of 3.6 ± 0.5. In human volunteers, [18F]DASA-23 crossed the intact blood-brain barrier and was rapidly cleared. In patients with GBM, [18F]DASA-23 successfully outlined tumors visible on contrast-enhanced MRI. The uptake of [18F]DASA-23 was markedly elevated in GBMs compared with normal brain, and it identified a metabolic nonresponder within 1 week of treatment initiation. CONCLUSIONS We developed and translated [18F]DASA-23 as a new tracer that demonstrated the visualization of aberrantly expressed PKM2 for the first time in human subjects. These results warrant further clinical evaluation of [18F]DASA-23 to assess its utility for imaging therapy-induced normalization of aberrant cancer metabolism.
Collapse
Affiliation(s)
- Corinne Beinat
- Department of Radiology, Molecular Imaging Program at Stanford, Stanford University School of Medicine, Stanford, California.
| | - Chirag B Patel
- Department of Radiology, Molecular Imaging Program at Stanford, Stanford University School of Medicine, Stanford, California
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California
| | - Tom Haywood
- Department of Radiology, Molecular Imaging Program at Stanford, Stanford University School of Medicine, Stanford, California
| | - Surya Murty
- Department of Radiology, Molecular Imaging Program at Stanford, Stanford University School of Medicine, Stanford, California
| | - Lewis Naya
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California
| | - Jessa B Castillo
- Department of Radiology, Molecular Imaging Program at Stanford, Stanford University School of Medicine, Stanford, California
| | - Samantha T Reyes
- Department of Radiology, Molecular Imaging Program at Stanford, Stanford University School of Medicine, Stanford, California
| | - Megan Phillips
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California
| | - Pablo Buccino
- Department of Radiology, Molecular Imaging Program at Stanford, Stanford University School of Medicine, Stanford, California
| | - Bin Shen
- Department of Radiology, Molecular Imaging Program at Stanford, Stanford University School of Medicine, Stanford, California
| | - Jun Hyung Park
- Department of Radiology, Molecular Imaging Program at Stanford, Stanford University School of Medicine, Stanford, California
| | - Mary Ellen I Koran
- Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Stanford University, Stanford, California
| | - Israt S Alam
- Department of Radiology, Molecular Imaging Program at Stanford, Stanford University School of Medicine, Stanford, California
| | - Michelle L James
- Department of Radiology, Molecular Imaging Program at Stanford, Stanford University School of Medicine, Stanford, California
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California
| | - Dawn Holley
- Department of Radiology, Molecular Imaging Program at Stanford, Stanford University School of Medicine, Stanford, California
| | - Kim Halbert
- Department of Radiology, Molecular Imaging Program at Stanford, Stanford University School of Medicine, Stanford, California
| | - Harsh Gandhi
- Department of Radiology, Molecular Imaging Program at Stanford, Stanford University School of Medicine, Stanford, California
| | - Joy Q He
- Stanford Institute for Stem Cell Biology and Regenerative Medicine, Department of Pathology, Stanford University School of Medicine, Stanford, California
| | - Monica Granucci
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, California
| | - Eli Johnson
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, California
| | - Daniel Dan Liu
- Stanford Institute for Stem Cell Biology and Regenerative Medicine, Department of Pathology, Stanford University School of Medicine, Stanford, California
| | - Nobuko Uchida
- Stanford Institute for Stem Cell Biology and Regenerative Medicine, Department of Pathology, Stanford University School of Medicine, Stanford, California
| | - Rahul Sinha
- Stanford Institute for Stem Cell Biology and Regenerative Medicine, Department of Pathology, Stanford University School of Medicine, Stanford, California
| | - Pauline Chu
- Stanford Human Research Histology Core, Stanford University School of Medicine, Stanford, California
| | - Donald E Born
- Department of Pathology, Neuropathology, Stanford University School of Medicine, Stanford, California
| | | | - Irving Weissman
- Stanford Institute for Stem Cell Biology and Regenerative Medicine, Department of Pathology, Stanford University School of Medicine, Stanford, California
| | - Melanie Hayden-Gephart
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, California
| | - Mehdi Khalighi
- Department of Radiology, Molecular Imaging Program at Stanford, Stanford University School of Medicine, Stanford, California
| | - Tarik F Massoud
- Department of Radiology, Molecular Imaging Program at Stanford, Stanford University School of Medicine, Stanford, California
- Division of Neuroimaging and Neurointervention, Department of Radiology, Stanford University School of Medicine, Stanford, California
| | - Andrei Iagaru
- Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Stanford University, Stanford, California
| | - Guido Davidzon
- Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Stanford University, Stanford, California
| | - Reena Thomas
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California
| | - Seema Nagpal
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California
| | - Lawrence D Recht
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California.
| | - Sanjiv Sam Gambhir
- Department of Radiology, Molecular Imaging Program at Stanford, Stanford University School of Medicine, Stanford, California
- Departments of Bioengineering and Materials Science & Engineering, Stanford University, Stanford, California
| |
Collapse
|
8
|
Laforest R, Khalighi M, Natsuaki Y, Rajagopal A, Chandramohan D, Byrd D, An H, Larson P, James SS, Sunderland JJ, Kinahan PE, Hope TA. Harmonization of PET image reconstruction parameters in simultaneous PET/MRI. EJNMMI Phys 2021; 8:75. [PMID: 34739621 PMCID: PMC8571452 DOI: 10.1186/s40658-021-00416-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Accepted: 10/01/2021] [Indexed: 01/17/2023] Open
Abstract
Objective Simultaneous PET/MRIs vary in their quantitative PET performance due to inherent differences in the physical systems and differences in the image reconstruction implementation. This variability in quantitative accuracy confounds the ability to meaningfully combine and compare data across scanners. In this work, we define image reconstruction parameters that lead to comparable contrast recovery curves across simultaneous PET/MRI systems. Method The NEMA NU-2 image quality phantom was imaged on one GE Signa and on one Siemens mMR PET/MRI scanner. The phantom was imaged at 9.7:1 contrast with standard spheres (diameter 10, 13, 17, 22, 28, 37 mm) and with custom spheres (diameter: 8.5, 11.5, 15, 25, 32.5, 44 mm) using a standardized methodology. Analysis was performed on a 30 min listmode data acquisition and on 6 realizations of 5 min from the listmode data. Images were reconstructed with the manufacturer provided iterative image reconstruction algorithms with and without point spread function (PSF) modeling. For both scanners, a post-reconstruction Gaussian filter of 3–7 mm in steps of 1 mm was applied. Attenuation correction was provided from a scaled computed tomography (CT) image of the phantom registered to the MR-based attenuation images and verified to align on the non-attenuation corrected PET images. For each of these image reconstruction parameter sets, contrast recovery coefficients (CRCs) were determined for the SUVmean, SUVmax and SUVpeak for each sphere. A hybrid metric combining the root-mean-squared discrepancy (RMSD) and the absolute CRC values was used to simultaneously optimize for best match in CRC between the two scanners while simultaneously weighting toward higher resolution reconstructions. The image reconstruction parameter set was identified as the best candidate reconstruction for each vendor for harmonized PET image reconstruction. Results The range of clinically relevant image reconstruction parameters demonstrated widely different quantitative performance across cameras. The best match of CRC curves was obtained at the lowest RMSD values with: for CRCmean, 2 iterations-7 mm filter on the GE Signa and 4 iterations-6 mm filter on the Siemens mMR, for CRCmax, 4 iterations-6 mm filter on the GE Signa, 4 iterations-5 mm filter on the Siemens mMR and for CRCpeak, 4 iterations-7 mm filter with PSF on the GE Signa and 4 iterations-7 mm filter on the Siemens mMR. Over all reconstructions, the RMSD between CRCs was 1.8%, 3.6% and 2.9% for CRC mean, max and peak, respectively. The solution of 2 iterations-3 mm on the GE Signa and 4 iterations-3 mm on Siemens mMR, both with PSF, led to simultaneous harmonization and with high CRC and low RMSD for CRC mean, max and peak with RMSD values of 2.8%, 5.8% and 3.2%, respectively. Conclusions For two commercially available PET/MRI scanners, user-selectable parameters that control iterative updates, image smoothing and PSF modeling provide a range of contrast recovery curves that allow harmonization in harmonization strategies of optimal match in CRC or high CRC values. This work demonstrates that nearly identical CRC curves can be obtained on different commercially available scanners by selecting appropriate image reconstruction parameters. Supplementary Information The online version contains supplementary material available at 10.1186/s40658-021-00416-0.
Collapse
Affiliation(s)
- Richard Laforest
- Mallinckrodt Institute of Radiology, Washington University, St. Louis, MO, USA.
| | - Mehdi Khalighi
- Department of Radiology, Stanford University, Stanford, CA, USA
| | - Yutaka Natsuaki
- Department of Radiation Oncology, University of California San Francisco, San Francisco, CA, USA
| | - Abhejit Rajagopal
- Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, USA
| | - Dharshan Chandramohan
- Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, USA
| | | | - Hongyu An
- Mallinckrodt Institute of Radiology, Washington University, St. Louis, MO, USA
| | - Peder Larson
- Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, USA
| | - Sara St James
- Department of Radiation Oncology, University of California San Francisco, San Francisco, CA, USA
| | | | | | - Thomas A Hope
- Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, USA
| |
Collapse
|
9
|
Chen KT, Toueg TN, Koran MEI, Davidzon G, Zeineh M, Holley D, Gandhi H, Halbert K, Boumis A, Kennedy G, Mormino E, Khalighi M, Zaharchuk G. True ultra-low-dose amyloid PET/MRI enhanced with deep learning for clinical interpretation. Eur J Nucl Med Mol Imaging 2021; 48:2416-2425. [PMID: 33416955 PMCID: PMC8891344 DOI: 10.1007/s00259-020-05151-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 12/06/2020] [Indexed: 02/02/2023]
Abstract
PURPOSE While sampled or short-frame realizations have shown the potential power of deep learning to reduce radiation dose for PET images, evidence in true injected ultra-low-dose cases is lacking. Therefore, we evaluated deep learning enhancement using a significantly reduced injected radiotracer protocol for amyloid PET/MRI. METHODS Eighteen participants underwent two separate 18F-florbetaben PET/MRI studies in which an ultra-low-dose (6.64 ± 3.57 MBq, 2.2 ± 1.3% of standard) or a standard-dose (300 ± 14 MBq) was injected. The PET counts from the standard-dose list-mode data were also undersampled to approximate an ultra-low-dose session. A pre-trained convolutional neural network was fine-tuned using MR images and either the injected or sampled ultra-low-dose PET as inputs. Image quality of the enhanced images was evaluated using three metrics (peak signal-to-noise ratio, structural similarity, and root mean square error), as well as the coefficient of variation (CV) for regional standard uptake value ratios (SUVRs). Mean cerebral uptake was correlated across image types to assess the validity of the sampled realizations. To judge clinical performance, four trained readers scored image quality on a five-point scale (using 15% non-inferiority limits for proportion of studies rated 3 or better) and classified cases into amyloid-positive and negative studies. RESULTS The deep learning-enhanced PET images showed marked improvement on all quality metrics compared with the low-dose images as well as having generally similar regional CVs as the standard-dose. All enhanced images were non-inferior to their standard-dose counterparts. Accuracy for amyloid status was high (97.2% and 91.7% for images enhanced from injected and sampled ultra-low-dose data, respectively) which was similar to intra-reader reproducibility of standard-dose images (98.6%). CONCLUSION Deep learning methods can synthesize diagnostic-quality PET images from ultra-low injected dose simultaneous PET/MRI data, demonstrating the general validity of sampled realizations and the potential to reduce dose significantly for amyloid imaging.
Collapse
Affiliation(s)
- Kevin T. Chen
- Department of Radiology, Stanford University, 1201 Welch Road, Stanford, CA 94305, USA
| | - Tyler N. Toueg
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA
| | | | - Guido Davidzon
- Department of Radiology, Stanford University, 1201 Welch Road, Stanford, CA 94305, USA
| | - Michael Zeineh
- Department of Radiology, Stanford University, 1201 Welch Road, Stanford, CA 94305, USA
| | - Dawn Holley
- Department of Radiology, Stanford University, 1201 Welch Road, Stanford, CA 94305, USA
| | - Harsh Gandhi
- Department of Radiology, Stanford University, 1201 Welch Road, Stanford, CA 94305, USA
| | - Kim Halbert
- Department of Radiology, Stanford University, 1201 Welch Road, Stanford, CA 94305, USA
| | - Athanasia Boumis
- Department of Radiology, Stanford University, 1201 Welch Road, Stanford, CA 94305, USA
| | - Gabriel Kennedy
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA
| | - Elizabeth Mormino
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA
| | - Mehdi Khalighi
- Department of Radiology, Stanford University, 1201 Welch Road, Stanford, CA 94305, USA
| | - Greg Zaharchuk
- Department of Radiology, Stanford University, 1201 Welch Road, Stanford, CA 94305, USA
| |
Collapse
|
10
|
Beinat C, Patel C, Haywood T, Murty S, Naya L, Hayden-Gephart M, Khalighi M, Massoud T, Iagaru A, Davidzon G, Thomas R, Nagpal S, Recht L, Gambhir S. BIMG-13. A NOVEL RADIOPHARMACEUTICAL ([18F]DASA-23) TO MONITOR PYRUVATE KINASE M2 INDUCED GLYCOLYTIC REPROGRAMMING IN GLIOBLASTOMA. Neurooncol Adv 2021. [PMCID: PMC7992247 DOI: 10.1093/noajnl/vdab024.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND Pyruvate kinase M2 (PKM2) catalyzes the final step in glycolysis, a key process of cancer metabolism. PKM2 is preferentially expressed by glioblastoma (GBM) cells with minimal expression in healthy brain, making it an important biomarker of cancer glycolytic re-programming. We describe the bench-to-bedside development, validation, and translation of a novel positron emission tomography (PET) tracer to study PKM2 in GBM. Specifically, we evaluated 1-((2-fluoro-6-[18F]fluorophenyl)sulfonyl)-4-((4-methoxyphenyl)sulfonyl)piperazine ([18F]DASA-23) in cell culture, mouse models of GBM, healthy human volunteers, and GBM patients. METHODS [18F]DASA-23 was synthesized with a molar activity of 100.47 ± 29.58 GBq/µmol and radiochemical purity >95%. We performed initial testing of [18F]DASA-23 in GBM cell culture and human GBM xenografts implanted orthotopically into mice. Next we produced [18F]DASA-23 under current Good Manufacturing Practices United States Food and Drug Administration (FDA) oversight, and evaluated it in healthy volunteers and a pilot cohort of patients with gliomas. RESULTS In mouse imaging studies, [18F]DASA-23 clearly delineated the U87 GBM from the surrounding healthy brain tissue and had a tumor-to-brain ratio (TBR) of 3.6 ± 0.5. In human volunteers, [18F]DASA-23 crossed the intact blood-brain barrier and was rapidly cleared. In GBM patients, [18F]DASA-23 successfully outlined tumors visible on contrast-enhanced magnetic resonance imaging (MRI). The uptake of [18F]DASA-23 was markedly elevated in GBMs compared to normal brain, and it was able to identify a metabolic non-responder within 1-week of treatment initiation. CONCLUSION We developed and translated [18F]DASA-23 as a promising new tracer that demonstrated the visualization of aberrantly expressed PKM2 for the first time in human subjects. These encouraging results warrant further clinical evaluation of [18F]DASA-23 to assess its utility for imaging therapy-induced normalization of aberrant cancer metabolism.
Collapse
|
11
|
Carlson ML, Toueg T, Corso N, Khalighi M, DiGiacomo P, Zaharchuk G, James ML, Greicius MD, Mormino EC, Zeineh M. Fractional anisotropy and tau‐PET show parallel changes in amnestic AD, MCI, and controls in the medial temporal lobe. Alzheimers Dement 2020. [DOI: 10.1002/alz.045305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
12
|
Chen KT, Gong E, de Carvalho Macruz FB, Xu J, Boumis A, Khalighi M, Poston KL, Sha SJ, Greicius MD, Mormino E, Pauly JM, Srinivas S, Zaharchuk G. Ultra-Low-Dose 18F-Florbetaben Amyloid PET Imaging Using Deep Learning with Multi-Contrast MRI Inputs. Radiology 2020; 296:E195. [PMID: 32804601 DOI: 10.1148/radiol.2020202527] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
13
|
Chen KT, Gong E, de Carvalho Macruz FB, Xu J, Boumis A, Khalighi M, Poston KL, Sha SJ, Greicius MD, Mormino E, Pauly JM, Srinivas S, Zaharchuk G. Ultra-Low-Dose 18F-Florbetaben Amyloid PET Imaging Using Deep Learning with Multi-Contrast MRI Inputs. Radiology 2019; 290:649-656. [PMID: 30526350 PMCID: PMC6394782 DOI: 10.1148/radiol.2018180940] [Citation(s) in RCA: 142] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 10/05/2018] [Accepted: 10/23/2018] [Indexed: 01/17/2023]
Abstract
Purpose To reduce radiotracer requirements for amyloid PET/MRI without sacrificing diagnostic quality by using deep learning methods. Materials and Methods Forty data sets from 39 patients (mean age ± standard deviation [SD], 67 years ± 8), including 16 male patients and 23 female patients (mean age, 66 years ± 6 and 68 years ± 9, respectively), who underwent simultaneous amyloid (fluorine 18 [18F]-florbetaben) PET/MRI examinations were acquired from March 2016 through October 2017 and retrospectively analyzed. One hundredth of the raw list-mode PET data were randomly chosen to simulate a low-dose (1%) acquisition. Convolutional neural networks were implemented with low-dose PET and multiple MR images (PET-plus-MR model) or with low-dose PET alone (PET-only) as inputs to predict full-dose PET images. Quality of the synthesized images was evaluated while Bland-Altman plots assessed the agreement of regional standard uptake value ratios (SUVRs) between image types. Two readers scored image quality on a five-point scale (5 = excellent) and determined amyloid status (positive or negative). Statistical analyses were carried out to assess the difference of image quality metrics and reader agreement and to determine confidence intervals (CIs) for reading results. Results The synthesized images (especially from the PET-plus-MR model) showed marked improvement on all quality metrics compared with the low-dose image. All PET-plus-MR images scored 3 or higher, with proportions of images rated greater than 3 similar to those for the full-dose images (-10% difference [eight of 80 readings], 95% CI: -15%, -5%). Accuracy for amyloid status was high (71 of 80 readings [89%]) and similar to intrareader reproducibility of full-dose images (73 of 80 [91%]). The PET-plus-MR model also had the smallest mean and variance for SUVR difference to full-dose images. Conclusion Simultaneously acquired MRI and ultra-low-dose PET data can be used to synthesize full-dose-like amyloid PET images. © RSNA, 2018 Online supplemental material is available for this article. See also the editorial by Catana in this issue.
Collapse
Affiliation(s)
- Kevin T. Chen
- From the Departments of Radiology (K.T.C., F.B.d.C.M., S.S., G.Z.),
Electrical Engineering (E.G., J.M.P.), and Neurology and Neurological Sciences
(A.B., K.L.P., S.J.S., M.D.G., E.M.), Stanford University, 1201 Welch Rd,
Stanford, CA 94305; Department of Engineering Physics, Tsinghua University,
Beijing, PR China (J.X.); GE Healthcare, Menlo Park, Calif (M.K.); and Subtle
Medical, Menlo Park, CA (E.G.)
| | - Enhao Gong
- From the Departments of Radiology (K.T.C., F.B.d.C.M., S.S., G.Z.),
Electrical Engineering (E.G., J.M.P.), and Neurology and Neurological Sciences
(A.B., K.L.P., S.J.S., M.D.G., E.M.), Stanford University, 1201 Welch Rd,
Stanford, CA 94305; Department of Engineering Physics, Tsinghua University,
Beijing, PR China (J.X.); GE Healthcare, Menlo Park, Calif (M.K.); and Subtle
Medical, Menlo Park, CA (E.G.)
| | - Fabiola Bezerra de Carvalho Macruz
- From the Departments of Radiology (K.T.C., F.B.d.C.M., S.S., G.Z.),
Electrical Engineering (E.G., J.M.P.), and Neurology and Neurological Sciences
(A.B., K.L.P., S.J.S., M.D.G., E.M.), Stanford University, 1201 Welch Rd,
Stanford, CA 94305; Department of Engineering Physics, Tsinghua University,
Beijing, PR China (J.X.); GE Healthcare, Menlo Park, Calif (M.K.); and Subtle
Medical, Menlo Park, CA (E.G.)
| | - Junshen Xu
- From the Departments of Radiology (K.T.C., F.B.d.C.M., S.S., G.Z.),
Electrical Engineering (E.G., J.M.P.), and Neurology and Neurological Sciences
(A.B., K.L.P., S.J.S., M.D.G., E.M.), Stanford University, 1201 Welch Rd,
Stanford, CA 94305; Department of Engineering Physics, Tsinghua University,
Beijing, PR China (J.X.); GE Healthcare, Menlo Park, Calif (M.K.); and Subtle
Medical, Menlo Park, CA (E.G.)
| | - Athanasia Boumis
- From the Departments of Radiology (K.T.C., F.B.d.C.M., S.S., G.Z.),
Electrical Engineering (E.G., J.M.P.), and Neurology and Neurological Sciences
(A.B., K.L.P., S.J.S., M.D.G., E.M.), Stanford University, 1201 Welch Rd,
Stanford, CA 94305; Department of Engineering Physics, Tsinghua University,
Beijing, PR China (J.X.); GE Healthcare, Menlo Park, Calif (M.K.); and Subtle
Medical, Menlo Park, CA (E.G.)
| | - Mehdi Khalighi
- From the Departments of Radiology (K.T.C., F.B.d.C.M., S.S., G.Z.),
Electrical Engineering (E.G., J.M.P.), and Neurology and Neurological Sciences
(A.B., K.L.P., S.J.S., M.D.G., E.M.), Stanford University, 1201 Welch Rd,
Stanford, CA 94305; Department of Engineering Physics, Tsinghua University,
Beijing, PR China (J.X.); GE Healthcare, Menlo Park, Calif (M.K.); and Subtle
Medical, Menlo Park, CA (E.G.)
| | - Kathleen L. Poston
- From the Departments of Radiology (K.T.C., F.B.d.C.M., S.S., G.Z.),
Electrical Engineering (E.G., J.M.P.), and Neurology and Neurological Sciences
(A.B., K.L.P., S.J.S., M.D.G., E.M.), Stanford University, 1201 Welch Rd,
Stanford, CA 94305; Department of Engineering Physics, Tsinghua University,
Beijing, PR China (J.X.); GE Healthcare, Menlo Park, Calif (M.K.); and Subtle
Medical, Menlo Park, CA (E.G.)
| | - Sharon J. Sha
- From the Departments of Radiology (K.T.C., F.B.d.C.M., S.S., G.Z.),
Electrical Engineering (E.G., J.M.P.), and Neurology and Neurological Sciences
(A.B., K.L.P., S.J.S., M.D.G., E.M.), Stanford University, 1201 Welch Rd,
Stanford, CA 94305; Department of Engineering Physics, Tsinghua University,
Beijing, PR China (J.X.); GE Healthcare, Menlo Park, Calif (M.K.); and Subtle
Medical, Menlo Park, CA (E.G.)
| | - Michael D. Greicius
- From the Departments of Radiology (K.T.C., F.B.d.C.M., S.S., G.Z.),
Electrical Engineering (E.G., J.M.P.), and Neurology and Neurological Sciences
(A.B., K.L.P., S.J.S., M.D.G., E.M.), Stanford University, 1201 Welch Rd,
Stanford, CA 94305; Department of Engineering Physics, Tsinghua University,
Beijing, PR China (J.X.); GE Healthcare, Menlo Park, Calif (M.K.); and Subtle
Medical, Menlo Park, CA (E.G.)
| | - Elizabeth Mormino
- From the Departments of Radiology (K.T.C., F.B.d.C.M., S.S., G.Z.),
Electrical Engineering (E.G., J.M.P.), and Neurology and Neurological Sciences
(A.B., K.L.P., S.J.S., M.D.G., E.M.), Stanford University, 1201 Welch Rd,
Stanford, CA 94305; Department of Engineering Physics, Tsinghua University,
Beijing, PR China (J.X.); GE Healthcare, Menlo Park, Calif (M.K.); and Subtle
Medical, Menlo Park, CA (E.G.)
| | - John M. Pauly
- From the Departments of Radiology (K.T.C., F.B.d.C.M., S.S., G.Z.),
Electrical Engineering (E.G., J.M.P.), and Neurology and Neurological Sciences
(A.B., K.L.P., S.J.S., M.D.G., E.M.), Stanford University, 1201 Welch Rd,
Stanford, CA 94305; Department of Engineering Physics, Tsinghua University,
Beijing, PR China (J.X.); GE Healthcare, Menlo Park, Calif (M.K.); and Subtle
Medical, Menlo Park, CA (E.G.)
| | - Shyam Srinivas
- From the Departments of Radiology (K.T.C., F.B.d.C.M., S.S., G.Z.),
Electrical Engineering (E.G., J.M.P.), and Neurology and Neurological Sciences
(A.B., K.L.P., S.J.S., M.D.G., E.M.), Stanford University, 1201 Welch Rd,
Stanford, CA 94305; Department of Engineering Physics, Tsinghua University,
Beijing, PR China (J.X.); GE Healthcare, Menlo Park, Calif (M.K.); and Subtle
Medical, Menlo Park, CA (E.G.)
| | - Greg Zaharchuk
- From the Departments of Radiology (K.T.C., F.B.d.C.M., S.S., G.Z.),
Electrical Engineering (E.G., J.M.P.), and Neurology and Neurological Sciences
(A.B., K.L.P., S.J.S., M.D.G., E.M.), Stanford University, 1201 Welch Rd,
Stanford, CA 94305; Department of Engineering Physics, Tsinghua University,
Beijing, PR China (J.X.); GE Healthcare, Menlo Park, Calif (M.K.); and Subtle
Medical, Menlo Park, CA (E.G.)
| |
Collapse
|
14
|
Khalighi M, Mikaeili M. A floating wide-band current source for electrical impedance tomography. Rev Sci Instrum 2018; 89:085107. [PMID: 30184672 DOI: 10.1063/1.5028435] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2018] [Accepted: 07/12/2018] [Indexed: 06/08/2023]
Abstract
The quality of reconstructed images in Electrical Impedance Tomography (EIT) depends on two essential factors: first, precision of the EIT hardware in current injection and voltage measurement and second, efficiency of its image reconstruction algorithm. Therefore the current source plays an important and a vital role in EIT instruments. Floating-load current sources constructed using sink and source drivers have better performance and higher output impedance than grounded-load (single-ended) current sources. In addition, a main feature of this kind is that the current source is not connected to the ground potential directly but via a large impedance. In this paper, we first focus on recent studies on designed EIT current sources, and after that, a practical design of a floating-load high output impedance current source-operating over a wide frequency band-will be proposed in detail. Simulation results of the proposed voltage-controlled current source (VCCS), along with some other models, will be shown and compared. At the end, the results of practical tests on the VCCS and a few EIT images, taken using our prototype EIT system coupled with the mentioned VCCS, will be illustrated which proves the quality of the proposed current source.
Collapse
Affiliation(s)
- M Khalighi
- Biomedical Engineering Group, Department of Engineering, Shahed University, Tehran, Iran
| | - M Mikaeili
- Biomedical Engineering Group, Department of Engineering, Shahed University, Tehran, Iran
| |
Collapse
|
15
|
Chen KT, Macruz F, Gong E, Khalighi M, Zaharchuk G. P4‐310: LOW‐DOSE AMYLOID PET RECONSTRUCTION USING A PRE‐TRAINED, MULTIMODAL DEEP LEARNING NETWORK. Alzheimers Dement 2018. [DOI: 10.1016/j.jalz.2018.07.133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
16
|
Quintana PJE, Khalighi M, Castillo Quiñones JE, Patel Z, Guerrero Garcia J, Martinez Vergara P, Bryden M, Mantz A. Traffic pollutants measured inside vehicles waiting in line at a major US-Mexico Port of Entry. Sci Total Environ 2018; 622-623:236-243. [PMID: 29216464 DOI: 10.1016/j.scitotenv.2017.11.319] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 11/22/2017] [Accepted: 11/27/2017] [Indexed: 06/07/2023]
Abstract
At US-Mexico border Ports of Entry, vehicles idle for long times waiting to cross northbound into the US. Long wait times at the border have mainly been studied as an economic issue, however, exposures to emissions from idling vehicles can also present an exposure risk. Here we present the first data on in-vehicle exposures to driver and passengers crossing the US-Mexico border at the San Ysidro, California Port of Entry (SYPOE). Participants were recruited who regularly commuted across the border in either direction and told to drive a scripted route between two border universities, one in the US and one in Mexico. Instruments were placed in participants' cars prior to commute to monitor-1-minute average levels of the traffic pollutants ultrafine particles (UFP), black carbon (BC) and carbon monoxide (CO) in the breathing zone of drivers and passengers. Location was determined by a GPS monitor. Results reported here are for 68 northbound participant trips. The highest median levels of in-vehicle UFP were recorded during the wait to cross at the SYPOE (median 29,692particles/cm3) significantly higher than the portion of the commute in the US (median 20,508particles/cm3) though not that portion in Mexico (median 22, 191particles/cm3). In-vehicle BC levels at the border were significantly lower than in other parts of the commute. Our results indicate that waiting in line at the SYPOE contributes a median 62.5% (range 15.5%-86.0%) of a cross-border commuter's exposure to UFP and a median 44.5% (range (10.6-79.7%) of exposure to BC inside the vehicle while traveling in the northbound direction. Reducing border wait time can significantly reduce in-vehicle exposures to toxic air pollutants such as UFP and BC, and these preventable exposures can be considered an environmental justice issue.
Collapse
Affiliation(s)
- Penelope J E Quintana
- San Diego State University Graduate School of Public Health, 5500 Campanile Drive, San Diego, CA 92182-4162, USA.
| | - Mehdi Khalighi
- Millersville University, Department of Applied Engineering, Safety & Technology Occupational Safety & Environmental Health Program, 40 East Frederick Street, Millersville, PA 17551, USA
| | - Javier Emmanuel Castillo Quiñones
- Universidad Autónoma de Baja California Facultad de Ciencias Quimicas e Ingenieria, Calzada Universidad 14418 Parque Industrial Internacional, Tijuana B.C. 22427, Mexico
| | - Zalak Patel
- San Diego State University Graduate School of Public Health, 5500 Campanile Drive, San Diego, CA 92182-4162, USA
| | - Jesus Guerrero Garcia
- Universidad Autónoma de Baja California Facultad de Ciencias Quimicas e Ingenieria, Calzada Universidad 14418 Parque Industrial Internacional, Tijuana B.C. 22427, Mexico
| | - Paulina Martinez Vergara
- Universidad Autónoma de Baja California Facultad de Ciencias Quimicas e Ingenieria, Calzada Universidad 14418 Parque Industrial Internacional, Tijuana B.C. 22427, Mexico
| | - Megan Bryden
- San Diego State University Graduate School of Public Health, 5500 Campanile Drive, San Diego, CA 92182-4162, USA
| | - Antoinette Mantz
- San Diego State University Graduate School of Public Health, 5500 Campanile Drive, San Diego, CA 92182-4162, USA
| |
Collapse
|
17
|
Yang J, Khalighi M, Hope TA, Ordovas K, Seo Y. Technical Note: Fast respiratory motion estimation using sorted singles without unlist processing: A feasibility study. Med Phys 2017; 44:1632-1637. [PMID: 28099995 DOI: 10.1002/mp.12115] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Revised: 01/10/2017] [Accepted: 01/12/2017] [Indexed: 11/09/2022] Open
Abstract
PURPOSE The study aims to demonstrate the feasibility of fast respiratory motion estimation using singles data available as a sorted format in list-mode files acquired in an integrated positron emission tomography/magnetic resonance imaging (PET/MRI) system for a proof-of-concept. METHODS The derivation of singles-driven respiratory motion (SDRM) is enabled by singles recorded and binned by second for each detector crystal in PET list-mode data acquired in a SIGNA PET/MR. The proposed method is to derive a SDRM trace by summing up all singles from all detectors through the PET data acquisition. To assess the feasibility of SDRM for data-driven gating (DDG), SDRM traces were derived from the list-mode data acquired in five liver-focused 68 Ga-DOTA-TOC PET/MRI scans, and compared with the traces derived from bellows (pressure belt). Pearson's correlation coefficients and trigger time differences at peak-inhalation phases between SDRM and bellows traces were measured for quantitative evaluation. RESULTS The method presented the average processing time of 4.2 ± 0.42 s (range: 3.9 ~ 4.7 s) for the derivation of SDRM traces. The majority of the time was spent for reading singles data from a list-mode file (3.1 ± 0.40 s, range: 2.7 ~ 3.7s). On average, the correlation coefficient of SDRM and bellows traces was 0.69 ± 0.16 (range: 0.41 ~ 0.80) and the time offset of SDRM-driven triggers from bellows-driven triggers was 0.25 ± 0.39 s (range: -0.85 ~ 2.69 s later than bellows triggers), demonstrating the similar patterns and phases of SDRM and bellows traces. CONCLUSIONS We introduced PET singles-driven respiratory motion (SDRM) estimation as a proof-of-principle, using sorted singles ready for immediate processing in list-mode data. The results demonstrated the feasibility of SDRM and its potential use for gated PET with fast processing time.
Collapse
Affiliation(s)
- Jaewon Yang
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, USA
| | | | - Thomas A Hope
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, USA.,Department of Radiology, San Francisco VA Medical Center, San Francisco, CA, USA
| | - Karen Ordovas
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, USA
| | - Youngho Seo
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, USA.,Joint Graduate Group in Bioengineering, University of California, San Francisco and Berkeley, CA, USA.,Department of Radiation Oncology, University of California, San Francisco, San Francisco, CA, USA
| |
Collapse
|
18
|
Saeedian M, Khalighi M, Azimi-Tafreshi N, Jafari GR, Ausloos M. Memory effects on epidemic evolution: The susceptible-infected-recovered epidemic model. Phys Rev E 2017; 95:022409. [PMID: 28297983 PMCID: PMC7217510 DOI: 10.1103/physreve.95.022409] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Revised: 12/20/2016] [Indexed: 12/02/2022]
Abstract
Memory has a great impact on the evolution of every process related to human societies. Among them, the evolution of an epidemic is directly related to the individuals' experiences. Indeed, any real epidemic process is clearly sustained by a non-Markovian dynamics: memory effects play an essential role in the spreading of diseases. Including memory effects in the susceptible-infected-recovered (SIR) epidemic model seems very appropriate for such an investigation. Thus, the memory prone SIR model dynamics is investigated using fractional derivatives. The decay of long-range memory, taken as a power-law function, is directly controlled by the order of the fractional derivatives in the corresponding nonlinear fractional differential evolution equations. Here we assume "fully mixed" approximation and show that the epidemic threshold is shifted to higher values than those for the memoryless system, depending on this memory "length" decay exponent. We also consider the SIR model on structured networks and study the effect of topology on threshold points in a non-Markovian dynamics. Furthermore, the lack of access to the precise information about the initial conditions or the past events plays a very relevant role in the correct estimation or prediction of the epidemic evolution. Such a "constraint" is analyzed and discussed.
Collapse
Affiliation(s)
- M Saeedian
- Department of Physics, Shahid Beheshti University, G.C., Evin, Tehran 19839, Iran
| | - M Khalighi
- Department of Physics, Shahid Beheshti University, G.C., Evin, Tehran 19839, Iran
| | - N Azimi-Tafreshi
- Physics Department, Institute for Advanced Studies in Basic Sciences, 45195-1159 Zanjan, Iran
| | - G R Jafari
- Department of Physics, Shahid Beheshti University, G.C., Evin, Tehran 19839, Iran
- School of Biological Sciences, Institute for Research in Fundamental Sciences (IPM), Tehran, Iran
- Center for Network Science, Central European University, H-1051 Budapest, Hungary
| | - M Ausloos
- GRAPES, rue de la Belle Jardinière 483, B-4031 Angleur, Belgium
- School of Management, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom
- eHumanities group, Royal Netherlands Academy of Arts and Sciences, Joan Muyskenweg 25, 1096 CJ, Amsterdam, The Netherlands
| |
Collapse
|
19
|
Delso G, Khalighi M, Hofbauer M, Porto M, Veit-Haibach P, von Schulthess G. Preliminary evaluation of image quality in a new clinical ToF-PET/MR scanner. EJNMMI Phys 2015; 1:A41. [PMID: 26501629 PMCID: PMC4544605 DOI: 10.1186/2197-7364-1-s1-a41] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023] Open
|
20
|
Delso G, Deller T, Khalighi M, Veit-Haibach P, von Schulthess G. Dynamic comparison of PET imaging performance between state-of-the-art ToF-PET/CT and ToF-PET/MR scanners. EJNMMI Phys 2015; 1:A75. [PMID: 26501666 PMCID: PMC4545837 DOI: 10.1186/2197-7364-1-s1-a75] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
|
21
|
Sesek R, Drinkaus P, Khalighi M, Tuckett RP, Bloswick DS. Development of a carpal tunnel syndrome screening method using structured interviews and vibrotactile testing. Work 2008; 30:403-411. [PMID: 18725703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023] Open
Abstract
Carpal tunnel syndrome (CTS) is a debilitating and expensive health problem. An inexpensive screening method that would differentiate between people who do not have CTS and those that may have CTS would be useful. The screening methodology investigated here had two phases: a structured interview and provocative vibrotactile testing (VT). The control group (n = 36) was composed of asymptomatic college students and faculty, the case group was composed of patients currently visiting an occupational medicine clinic for symptoms consistent with CTS. The case group was subdivided into positive and negative for nerve conduction latency, NCL+ (n = 21) and NCL- (n = 13), respectively. Using a scored, structured interview, 33 of the controls and none of the symptomatic cases were identified as non-CTS. The results from the provocative flexion VT indicated that if the difference between the age corrected baseline and the threshold at 15 minutes is 15 microm or more, the subject was likely to be NCL+ (odds ratio 12.6, 95% CI 3.8 to 41.8). Further research may improve this screening methodology to not only determine whether or not a person has CTS, but also to determine the level of median nerve impingement or damage.
Collapse
Affiliation(s)
- Richard Sesek
- University of Utah, Salt Lake City, UT 84112-9208, USA.
| | | | | | | | | |
Collapse
|
22
|
Sesek RF, Khalighi M, Bloswick DS, Anderson M, Tuckett RP. Effects of prolonged wrist flexion on transmission of sensory information in carpal tunnel syndrome. J Pain 2006; 8:137-51. [PMID: 16949877 DOI: 10.1016/j.jpain.2006.06.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2006] [Revised: 06/26/2006] [Accepted: 06/30/2006] [Indexed: 01/18/2023]
Abstract
UNLABELLED Carpal tunnel syndrome presents a constellation of symptoms which include discomfort (eg, pain, paraesthesia) and diminished sense of touch. This exploratory study simultaneously measured changes in tactile threshold and discomfort ratings during prolonged wrist flexion in symptomatic patients from a rehabilitation clinic and from a control population. Prolonged (15 min) wrist flexion significantly increased tactile threshold and discomfort ratings above baseline levels in both symptomatic and control populations. Sixty-two percent of the symptomatic sample was found to have abnormal conduction latency. Tactile threshold in symptomatic subjects with normal conduction latency (n = 13) did not differ significantly from control subjects (n = 36) at baseline but showed significant elevation during wrist flexion. In contrast, subjects with abnormal conduction latency (n = 21) exhibited significant elevation relative to control subjects at baseline and throughout wrist flexion as well as a slower recovery after flexion. Conduction latency correlated with baseline (r = .52, P < .0001) and 15-min (r = .67, P < .0001) tactile threshold for the entire subject population, as well as 15-min threshold (r = .53, P = .013) for the subpopulation with abnormal conduction latency. At 2.5 min after flexion, correlation was significant for whole (r = .64, P < .0001) and abnormal conduction latency (r = .58, P = .0063) samples. Regression slope of tactile threshold versus conduction latency was significantly greater than zero and did not differ significantly from linearity. The study demonstrates that increases in mechanosensory threshold and discomfort ratings during prolonged wrist flexion are more profound (and recovery less rapid) in patients with electrophysiologic evidence of injury. PERSPECTIVE This study demonstrates a provocative procedure that enhances the symptoms of carpal tunnel syndrome. This measure may help clinicians discriminate median nerve compression from other types of peripheral nerve injury and help researchers investigate the impact of mechanical stress, tissue compression, and vascular stasis on compression-related neuropathy.
Collapse
Affiliation(s)
- Richard F Sesek
- Department of Mechanical Engineering, University of Utah, Salt Lake City, Utah, USA
| | | | | | | | | |
Collapse
|
23
|
Khalighi M, Brzezinski MR, Chen H, Juchau MR. Inhibition of human prenatal biosynthesis of all-trans-retinoic acid by ethanol, ethanol metabolites, and products of lipid peroxidation reactions: a possible role for CYP2E1. Biochem Pharmacol 1999; 57:811-21. [PMID: 10075087 DOI: 10.1016/s0006-2952(98)00362-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Biotransformation of all-trans-retinol (t-ROH) and all-trans-retinal (t-RAL) to all-trans-retinoic acid (t-RA) in human prenatal hepatic tissues (53-84 gestational days) was investigated with HPLC using human adult hepatic tissues as positive controls. Catalysis of the biotransformation of t-ROH by prenatal human cytosolic fractions resulted in accumulation of t-RAL with minimal t-RA. Oxidations of t-ROH catalyzed by prenatal cytosol were supported by both NAD+ and NADP+, although NAD+ was a much better cofactor. In contrast, catalysis of the oxidation of t-RAL to t-RA appeared to be solely NAD+ dependent. Substrate Km values for conversions of t-ROH to t-RAL and of t-RAL to t-RA were 82.4 and 65.8 microM, respectively. At concentrations of 10 and 90 mM, ethanol inhibited the conversion of t-ROH to t-RAL by 25 and 43%, respectively, but did not inhibit the conversion of t-RAL to t-RA significantly. In contrast, acetaldehyde reduced the conversion of t-RAL to t-RA by 25 and 87% at 0.1 and 10 mM respective concentrations. Several alcohols and aldehydes known to be generated from lipid peroxides also exhibited significant inhibition of t-RA biosynthesis in human prenatal hepatic tissues. Among the compounds tested, 4-hydroxy-2-nonenal (4-HNE) was highly effective in inhibiting the conversion of t-RAL to t-RA. A 20% inhibition was observed at a concentration of only 0.001 mM, and nearly complete inhibition was produced at 0.1 mM. Human fetal and embryonic hepatic tissues each exhibited significant CYP2E1 expression as assessed with chlorzoxazone 6-hydroxylation, a highly sensitive western blotting technique, and reverse transcriptase-polymerase chain reaction (PCR) (RT-PCR), suggesting that lipid peroxidation can be initiated via CYP2E1-catalyzed ethanol oxidation in human embryonic hepatic tissues. In summary, these studies suggest that ethanol may affect the biosynthesis of t-RA in human prenatal hepatic tissues directly and indirectly. Ethanol and its major oxidative metabolite, acetaldehyde, both inhibit the generation of t-RA. Concurrently, the CYP2E1-catalyzed oxidation of ethanol can initiate lipid peroxidation via generation of a variety of free radicals. The lipid peroxides thereby generated could then be further converted via CYP2E1-catalyzed reactions to alcohols and aldehydes, including 4-HNE, that act as potent inhibitors of t-RA synthesis.
Collapse
Affiliation(s)
- M Khalighi
- Department of Pharmacology, School of Medicine, University of Washington, Seattle 98195, USA
| | | | | | | |
Collapse
|
24
|
Paine MF, Khalighi M, Fisher JM, Shen DD, Kunze KL, Marsh CL, Perkins JD, Thummel KE. Characterization of interintestinal and intraintestinal variations in human CYP3A-dependent metabolism. J Pharmacol Exp Ther 1997; 283:1552-62. [PMID: 9400033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Cytochrome P450 3A (CYP3A) metabolizes a diverse array of clinically important drugs. For some of these (e.g., cyclosporine, verapamil, midazolam), CYP3A in the intestinal mucosa contributes to their extensive and variable first-pass extraction. To further characterize this phenomenon, we measured CYP3A content and catalytic activity toward the probe substrate midazolam in mucosa isolated from duodenal, jejunal and ileal sections of 20 human donor intestines. For comparison, the same measurements were performed for 20 human donor livers, eight of which were obtained from the same donors as eight of the intestines. Excellent correlations existed between homogenate and microsomal CYP3A content for the three intestinal regions. Median microsomal CYP3A content was greatest in the duodenum and lowest in the ileum (31 vs. 17 pmol/mg of protein). With respect to midazolam 1'-hydroxylation kinetics, the median Km for each intestinal region was similar to the median hepatic Km, approximately 4 microM. In contrast, the median Vmax decreased from liver to duodenum to jejunum to ileum (850 vs. 644 vs. 426 vs. 68 pmol/min/mg). Intrinsic clearance (Vmax/Km) followed a similar trend for the intestinal regions; median duodenal intrinsic clearance was comparable to hepatic intrinsic clearance (157 and 200 microl/min/mg, respectively). Vmax correlated with CYP3A content for all tissues except the ileum. Duodenal and jejunal Vmax and CYP3A content varied by >30-fold among donors. Microsomes prepared from every other 1-foot section of six intestines were also analyzed for CYP3A as well as for two coenzymes. In general, CYP3A activity, CYP3A content and CYP reductase activity rose slightly from duodenum to middle jejunum and then declined to distal jejunum and ileum. Cytochrome b5 content and cytochrome b5 reductase activity varied little throughout the intestinal tract. Regional intrinsic midazolam 1'-hydroxylation clearance was greatest for the jejunum, followed by the duodenum and ileum (144, 50 and 19 ml/min, respectively). Collectively, these results demonstrate that the upper small intestine serves as the major site for intestinal CYP3A-mediated first-pass metabolism and provides a rationale for interindividual differences in oral bioavailability for some CYP3A substrates.
Collapse
Affiliation(s)
- M F Paine
- Department of Pharmaceutics, University of Washington, Seattle, Washington 98195, USA
| | | | | | | | | | | | | | | |
Collapse
|
25
|
Ramesh N, Kim ST, Wei MQ, Khalighi M, Osborne WR. High-titer bicistronic retroviral vectors employing foot-and-mouth disease virus internal ribosome entry site. Nucleic Acids Res 1996; 24:2697-700. [PMID: 8758998 PMCID: PMC146003 DOI: 10.1093/nar/24.14.2697] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Bicistronic retroviral vectors were constructed containing the foot-and-mouth disease virus (FMDV) internal ribosome entry site (IRES) followed by the coding region of beta-galactosidase (beta-gal) or therapeutic genes, with the selectable neomycin phosphotransferase gene under the control of the viral long terminal repeat (LTR) promoter. LNFX, a vector with a multiple cloning site 3' to foot-and-mouth disease virus IRES, was used to construct vectors encoding rat erythropoietin (EP), rat granulocyte colony-stimulating factor (G-CSF), human adenosine deaminase (ADA) and beta-gal. In transduced primary rat vascular smooth muscle cells the cytokines were expressed at high levels, similar to those obtained from vectors employing the viral LTR promoter. LNFZ, a vector encoding beta-gal, had a 10-fold increase in titer over that of LNPoZ, a comparable vector containing the poliovirus (Po) internal ribosome entry site. Primary canine vascular smooth muscle cells infected with LNFZ and LNPoZ expressed similar activities of beta-gal and neomycin phosphotransferase (NPT). Overall, these vectors had titers between 10(6) and 2 x 10(7) c.f.u./ml, indicating that foot-and-mouth disease virus IRES provides high-titer bicistronic vectors with high-level two gene expression.
Collapse
Affiliation(s)
- N Ramesh
- Department of Pediatrics, University of Washington School of Medicine Seattle 98195, USA
| | | | | | | | | |
Collapse
|