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Xu R, Walsh EG, Watanabe T, Sasaki Y. Shift in excitation-inhibition balance underlies perceptual learning of temporal discrimination. Neuropsychologia 2024; 195:108814. [PMID: 38316210 PMCID: PMC10923091 DOI: 10.1016/j.neuropsychologia.2024.108814] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 11/28/2023] [Accepted: 01/29/2024] [Indexed: 02/07/2024]
Abstract
Temporal perceptual learning (TPL) constitutes a unique and profound demonstration of neural plasticity within the brain. Our understanding for the neurometabolic changes associated with TPL on the other hand has been limited in part by the use of traditional fMRI approaches. Since plasticity in the visual cortex has been shown to underlie perceptual learning of visual information, we tested the hypothesis that TPL of an auditory interval involves a similar change in plasticity of the auditory pathway and if so, whether these changes take place in a lower-order sensory-specific brain area such as the primary auditory cortex (A1), or a higher-order modality-independent brain area such as the inferior parietal cortex (IPC). This distinction will inform us of the mechanisms underlying perceptual learning as well as the locus of change as it relates to TPL. In the present study, we took advantage of a new technique: proton magnetic resonance spectroscopy (MRS) in combination with psychophysical measures to provide the first evidence of changes in neurometabolic processing following 5 days of temporal discrimination training. We measured the (E)xcitation-to-(I)nhibition ratio as an index of learning in the right IPC and left A1 while participants learned an auditory two-tone discrimination task. During the first day of training, we found a significant task-related increase in functional E/I ratio within the IPC. While the A1 exhibited the opposite pattern of neurochemical activity, this relationship did not reach statistical significance. After timing performance has reached a plateau, there were no further changes to functional E/I. These findings support the hypothesis that improvements in temporal discrimination relies on neuroplastic changes in the IPC, but it is possible that both areas work synergistically to acquire a temporal interval.
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Affiliation(s)
- Rannie Xu
- Department of Cognitive, Linguistic & Psychological Sciences, United States.
| | - Edward G Walsh
- Department of Neuroscience, Brown University, Providence, 02912, United States
| | - Takeo Watanabe
- Department of Cognitive, Linguistic & Psychological Sciences, United States
| | - Yuka Sasaki
- Department of Cognitive, Linguistic & Psychological Sciences, United States
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White TL, Gonsalves MA, Harris AD, Walsh EG, Joyce HE. Brain Glutamate Dynamics Predict Positive Agency in Healthy Women: Insights from Combined Application of Pharmacological Challenge, Comprehensive Affective Assessment, and Magnetic Resonance Spectroscopy. ACS Chem Neurosci 2024; 15:491-502. [PMID: 38237555 DOI: 10.1021/acschemneuro.3c00521] [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] [Indexed: 01/30/2024] Open
Abstract
Contributions of brain glutamate (Glu) to conscious emotion are not well understood. Here, we evaluate the relationship of experimentally induced change in neocortical Glu (ΔGlu) and subjective states in well individuals, using combined application of pharmacological challenge, magnetic resonance spectroscopy (MRS), and comprehensive affective assessment. Drug challenge with d-amphetamine (AMP) (20 mg oral), methamphetamine (MA) (Desoxyn, 20 mg oral), and placebo (PBO) was conducted on three separate test days in a within-subjects double blind design. Proton MRS quantified neurometabolites in the right dorsal anterior cingulate cortex 140-150 min post-drug and PBO. Subjective states were assessed at half hour intervals over 5.5 h on each session, yielding 3792 responses per participant (91,008 responses overall, N = 24 participants), with self-reports reduced by principal components analysis (PCA). PCA produced a primary factor score of AMP- and MA-induced positive agency (ΔPA). MRS indicated drug-induced ΔGlu related positively to ΔPA (ΔGluMA r = +0.44, p < 0.05, N = 21), with large effects in females (ΔGluMA r = +0.52, p < 0.05; ΔGluAMP r = +0.61, p < 0.05, N = 11). Subjective states related to ΔGlu included rise in subjective stimulation, vigor, friendliness, elation, positive mood, positive affect (r's = +0.51 to +0.74, p < 0.05), and alleviation of anxiety in females (r = -0.61, p < 0.05, N = 11). These self-reports correlated with ΔGlu to the extent they loaded on ΔPA (r = 0.95 AMP, p = 5 × 10-10; r = 0.63 MA, p = 0.0015, N = 11), indicating the coherence of ΔGlu effects on emotional states. Timing data indicated Glu shaped positive emotion both concurrently and prospectively, with no relationship with pre-MRS emotion (ΔGluAMP r = +0.59 to +0.65, p's < 0.05; ΔGluMA r = +0.53, p < 0.05, N = 11). Together these findings indicate substantive, mechanistic contributions of neocortical Glu to positive agentic states in healthy individuals, which are most readily observed in women. The findings illustrate the promise of combined application of pharmacological challenge, comprehensive affective assessment, and MRS neuroimaging techniques in basic and clinical studies.
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Affiliation(s)
- Tara L White
- Carney Institute for Brain Science, Brown University, Providence, Rhode Island 02912. United States
- Department of Behavioral and Social Sciences, School of Public Health, Brown University, Providence, Rhode Island 02912. United States
- Center for Alcohol and Addiction Studies, Brown University, Providence, Rhode Island 02912. United States
- Center for Human Rights and Humanitarian Studies, Watson Institute, Brown University, Providence, Rhode Island 02912. United States
- University of Cambridge, Clare Hall, Cambridge CB3 9AL England. U.K
| | - Meghan A Gonsalves
- Neuroscience Graduate Program, Brown University, Providence, Rhode Island 02912. United States
| | - Ashley D Harris
- Department of Radiology, CAIR Program, Alberta Children's Hospital Research Institute, and Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Edward G Walsh
- Carney Institute for Brain Science, Brown University, Providence, Rhode Island 02912. United States
| | - Hannah E Joyce
- Undergraduate Program in Cognitive Neuroscience, Brown University, Providence, Rhode Island 02912. United States
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White TL, Gonsalves MA, Harris AD, Walsh EG, Joyce HE. Brain Glutamate Dynamics Predict Positive Agency in Healthy Women. Res Sq 2023:rs.3.rs-3021527. [PMID: 37398402 PMCID: PMC10312947 DOI: 10.21203/rs.3.rs-3021527/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Contributions of brain glutamate to conscious emotion are not well understood. Here we evaluate the relationship of experimentally-induced change in neocortical glutamate (ΔGlu) and subjective states in well individuals. Drug challenge with d-amphetamine (AMP; 20 mg oral), methamphetamine (MA; Desoxyn®, 20 mg oral), and placebo (PBO) was conducted on three separate test days in a within-subjects double blind design. Proton magnetic resonance spectroscopy (MRS) quantified neurometabolites in the right dorsal anterior cingulate cortex (dACC) 140-150 m post-drug and PBO. Subjective states were assessed at half hour intervals over 5.5-hours on each session, yielding 3,792 responses per participant (91,008 responses overall, N=24 participants). Self-reports were reduced by principal components analysis to a single factor score of AMP- and MA-induced Positive Agency (ΔPA) in each participant. We found drug-induced ΔGlu related positively with ΔPA (ΔGluMA r=+.44, p<.05, N=21), with large effects in females (ΔGluMA r=+.52, p<.05; ΔGluAMP r=+.61, p<.05, N=11). States related to ΔGlu in females included rise in subjective stimulation, vigor, friendliness, elation, positive mood, positive affect (r's=+.51 to +.74, p<.05), and alleviation of anxiety (r=-.61, p<.05, N=11). Self-reports correlated with DGlu to the extent they loaded on ΔPA (r=.95 AMP, p=5×10-10; r=.63 MA, p=.0015, N=11), indicating coherence of ΔGlu effects. Timing data indicated Glu shaped emotion both concurrently and prospectively, with no relationship to pre-MRS emotion (ΔGluAMP r=+.59 to +.65, p's<.05; ΔGluMA r=+.53, p<.05, N=11). Together these findings indicate substantive, mechanistic contributions of neocortical Glu to positive agentic states in healthy individuals, most readily observed in women.
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Rmus M, He M, Baribault B, Walsh EG, Festa EK, Collins AGE, Nassar MR. Age-related differences in prefrontal glutamate are associated with increased working memory decay that gives the appearance of learning deficits. eLife 2023; 12:85243. [PMID: 37070807 PMCID: PMC10174689 DOI: 10.7554/elife.85243] [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] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 04/17/2023] [Indexed: 04/19/2023] Open
Abstract
The ability to use past experience to effectively guide decision making declines in older adulthood. Such declines have been theorized to emerge from either impairments of striatal reinforcement learning systems (RL) or impairments of recurrent networks in prefrontal and parietal cortex that support working memory (WM). Distinguishing between these hypotheses has been challenging because either RL or WM could be used to facilitate successful decision making in typical laboratory tasks. Here we investigated the neurocomputational correlates of age-related decision making deficits using an RL-WMtask to disentangle these mechanisms, a computational model to quantify them, and magnetic resonance spectroscopy to link them to their molecular bases. Our results reveal that task performance is worse in older age, in a manner best explained by working memory deficits, as might be expected if cortical recurrent networks were unable to sustain persistent activity across multiple trials. Consistent with this, we show that older adults had lower levels of prefrontal glutamate, the excitatory neurotransmitter thought to support persistent activity, compared to younger adults. Individuals with the lowest prefrontal glutamate levels displayed the greatest impairments in working memory after controlling for other anatomical and metabolic factors. Together, our results suggest that lower levels of prefrontal glutamate may contribute to failures of working memory systems and impaired decision making in older adulthood.
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Affiliation(s)
- Milena Rmus
- University of California, Berkeley, Berkeley, United States
| | - Mingjian He
- Massachusetts Institute of Technology, Boston, United States
| | - Beth Baribault
- University of California, Berkeley, Berkeley, United States
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Flannery SW, Beveridge JE, Proffen BL, Walsh EG, Kramer DE, Murray MM, Kiapour AM, Fleming BC. Predicting anterior cruciate ligament failure load with T 2* relaxometry and machine learning as a prospective imaging biomarker for revision surgery. Sci Rep 2023; 13:3524. [PMID: 36864112 PMCID: PMC9981601 DOI: 10.1038/s41598-023-30637-5] [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] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 02/27/2023] [Indexed: 03/04/2023] Open
Abstract
Non-invasive methods to document healing anterior cruciate ligament (ACL) structural properties could potentially identify patients at risk for revision surgery. The objective was to evaluate machine learning models to predict ACL failure load from magnetic resonance images (MRI) and to determine if those predictions were related to revision surgery incidence. It was hypothesized that the optimal model would demonstrate a lower mean absolute error (MAE) than the benchmark linear regression model, and that patients with a lower estimated failure load would have higher revision incidence 2 years post-surgery. Support vector machine, random forest, AdaBoost, XGBoost, and linear regression models were trained using MRI T2* relaxometry and ACL tensile testing data from minipigs (n = 65). The lowest MAE model was used to estimate ACL failure load for surgical patients at 9 months post-surgery (n = 46) and dichotomized into low and high score groups via Youden's J statistic to compare revision incidence. Significance was set at alpha = 0.05. The random forest model decreased the failure load MAE by 55% (Wilcoxon signed-rank test: p = 0.01) versus the benchmark. The low score group had a higher revision incidence (21% vs. 5%; Chi-square test: p = 0.09). ACL structural property estimates via MRI may provide a biomarker for clinical decision making.
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Affiliation(s)
- Sean W Flannery
- Department of Orthopaedics, Warren Alpert Medical School of Brown University/Rhode Island Hospital, Coro West, Suite 402, 1 Hoppin St, Providence, RI, 02903, USA
| | - Jillian E Beveridge
- Department of Orthopaedics, Warren Alpert Medical School of Brown University/Rhode Island Hospital, Coro West, Suite 402, 1 Hoppin St, Providence, RI, 02903, USA
| | - Benedikt L Proffen
- Division of Sports Medicine, Department of Orthopaedic Surgery, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Edward G Walsh
- Department of Neuroscience, Division of Biology and Medicine, Brown University, Providence, RI, USA
| | - Dennis E Kramer
- Division of Sports Medicine, Department of Orthopaedic Surgery, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Martha M Murray
- Division of Sports Medicine, Department of Orthopaedic Surgery, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Ata M Kiapour
- Division of Sports Medicine, Department of Orthopaedic Surgery, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Braden C Fleming
- Department of Orthopaedics, Warren Alpert Medical School of Brown University/Rhode Island Hospital, Coro West, Suite 402, 1 Hoppin St, Providence, RI, 02903, USA.
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Flannery SW, Barnes DA, Costa MQ, Menghini D, Kiapour AM, Walsh EG, Kramer DE, Murray MM, Fleming BC. Automated segmentation of the healed anterior cruciate ligament from T 2 * relaxometry MRI scans. J Orthop Res 2023; 41:649-656. [PMID: 35634860 PMCID: PMC9708947 DOI: 10.1002/jor.25390] [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] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 05/16/2022] [Accepted: 05/26/2022] [Indexed: 02/04/2023]
Abstract
Collagen organization of the anterior cruciate ligament (ACL) can be evaluated using T2 * relaxometry. However, T2 * mapping requires manual image segmentation, which is a time-consuming process and prone to inter- and intra- segmenter variability. Automating segmentation would address these challenges. A model previously trained using Constructive Interference in Steady State (CISS) scans was applied to T2 * segmentation via transfer learning. It was hypothesized that there would be no significant differences in the model's segmentation performance between T2 * and CISS, structural measures versus ground truth manual segmentation, and reliability versus independent and retest manual segmentation. Transfer learning was conducted using 54 T2 * scans of the ACL. Segmentation performance was assessed with Dice coefficient, precision, and sensitivity, and structurally with T2 * value, volume, subvolume proportions, and cross-sectional area. Model performance relative to independent manual segmentation and repeated segmentation by the ground truth segmenter (retest) were evaluated on a random subset. Segmentation performance was analyzed with Mann-Whitney U tests, structural measures with Wilcoxon signed-rank tests, and performance relative to manual segmentation with repeated-measures analysis of variance/Tukey tests (α = 0.05). T2 * segmentation performance was not significantly different from CISS on all measures (p > 0.35). No significant differences were detected in structural measures (p > 0.50). Automatic segmentation performed as well as the retest on all segmentation measures, whereas independent segmentations were lower than retest and/or automatic segmentation (p < 0.023). Structural measures were not significantly different between segmenters. The automatic segmentation model performed as well on the T2 * sequence as on CISS and outperformed independent manual segmentation while performing as well as retest segmentation.
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Affiliation(s)
- Sean W. Flannery
- Department of Orthopaedics, Warren Alpert Medical School of Brown University/Rhode Island Hospital, Providence, RI, USA
| | - Dominique A. Barnes
- Department of Orthopaedics, Warren Alpert Medical School of Brown University/Rhode Island Hospital, Providence, RI, USA
| | - Meggin Q. Costa
- Department of Orthopaedics, Warren Alpert Medical School of Brown University/Rhode Island Hospital, Providence, RI, USA
| | - Danilo Menghini
- Department of Orthopaedic Surgery, Boston Children’s Hospital, Harvard Medical School, Boston, MA, USA
| | - Ata M. Kiapour
- Department of Orthopaedic Surgery, Boston Children’s Hospital, Harvard Medical School, Boston, MA, USA
| | - Edward G. Walsh
- Department of Neuroscience, Division of Biology and Medicine, Brown University, Providence, RI, USA
| | - Dennis E. Kramer
- Department of Orthopaedic Surgery, Boston Children’s Hospital, Harvard Medical School, Boston, MA, USA
| | - Martha M. Murray
- Department of Orthopaedic Surgery, Boston Children’s Hospital, Harvard Medical School, Boston, MA, USA
| | - Braden C. Fleming
- Department of Orthopaedics, Warren Alpert Medical School of Brown University/Rhode Island Hospital, Providence, RI, USA
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Flannery SW, Walsh EG, Sanborn RM, Chrostek CA, Costa MQ, Kaushal SG, Murray MM, Fleming BC, Kiapour AM. Reproducibility and postacquisition correction methods for quantitative magnetic resonance imaging of the anterior cruciate ligament (ACL). J Orthop Res 2022; 40:2908-2913. [PMID: 35266588 PMCID: PMC9463398 DOI: 10.1002/jor.25319] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 02/15/2022] [Accepted: 03/01/2022] [Indexed: 02/04/2023]
Abstract
Quantitative magnetic resonance imaging has been used to evaluate the structural integrity of knee joint structures. However, variations in acquisition parameters between scanners pose significant challenges. Understanding the effect of small differences in acquisition parameters for quantitative sequences is vital to the validity of cross-institutional studies, and for the harmonization of large, heterogeneous datasets to train machine learning models. The study objective was to assess the reproducibility of T2 * relaxometry and the constructive interference in steady-state sequence (CISS) across scanners, with minimal hardware-necessitated changes to acquisition parameters. It was hypothesized that there would be no significant differences between scanners in anterior cruciate ligament T2 * relaxation times and CISS signal intensities (SI). Secondarily, it was hypothesized that differences could be corrected by rescaling the SI distribution to harmonize between scanners. Seven volunteers were scanned on 3T Prisma and Tim Trio scanners (Siemens). Three correction methods were evaluated for T2 *: inverse echo time scaling, z-scoring, and Nyúl histogram matching. For CISS, scans were normalized to cortical bone, scaled by the background noise ratio, and log-transformed. Before correction, significant mean differences of 6.0 ± 3.2 ms (71.8%; p = 0.02) and 0.49 ± 0.15 units (40.7%; p = 0.02) for T2 * and CISS across scanners were observed, respectively. After rescaling, T2 * differences decreased to 2.6 ± 2.7 ms (23.9%; p = 0.03), 1.3 ± 2.5 ms (10.9%; p = 0.13), and 1.27 ± 3.0 ms (19.6%; p = 0.40) for inverse echo time, z-scoring, and Nyúl, respectively, while CISS decreased to 0.01 ± 0.11 units (4.0%; p = 0.87). These findings suggest that small acquisition parameter differences may lead to large changes in T2 * and SI values that must be reconciled to compare data across magnets.
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Affiliation(s)
- Sean W. Flannery
- Department of Orthopaedics, Warren Alpert Medical School of Brown University/Rhode Island Hospital, Providence, RI, USA
| | - Edward G. Walsh
- Department of Neuroscience, Division of Biology and Medicine, Brown University, Providence, RI, USA
| | - Ryan M. Sanborn
- Division of Sports Medicine, Department of Orthopaedic Surgery, Boston Children’s Hospital, Harvard Medical School, Boston, MA, USA
| | - Cynthia A. Chrostek
- Department of Orthopaedics, Warren Alpert Medical School of Brown University/Rhode Island Hospital, Providence, RI, USA
| | - Meggin Q. Costa
- Department of Orthopaedics, Warren Alpert Medical School of Brown University/Rhode Island Hospital, Providence, RI, USA
| | - Shankar G. Kaushal
- Division of Sports Medicine, Department of Orthopaedic Surgery, Boston Children’s Hospital, Harvard Medical School, Boston, MA, USA
| | - Martha M. Murray
- Division of Sports Medicine, Department of Orthopaedic Surgery, Boston Children’s Hospital, Harvard Medical School, Boston, MA, USA
| | - Braden C. Fleming
- Department of Orthopaedics, Warren Alpert Medical School of Brown University/Rhode Island Hospital, Providence, RI, USA
| | - Ata M. Kiapour
- Division of Sports Medicine, Department of Orthopaedic Surgery, Boston Children’s Hospital, Harvard Medical School, Boston, MA, USA
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Chen X, Zhang J, Wu Y, Tucker R, Baird GL, Domonoske R, Barrios-Anderson A, Lim YP, Bath K, Walsh EG, Stonestreet BS. Inter-alpha Inhibitor Proteins Ameliorate Brain Injury and Improve Behavioral Outcomes in a Sex-Dependent Manner After Exposure to Neonatal Hypoxia Ischemia in Newborn and Young Adult Rats. Neurotherapeutics 2022; 19:528-549. [PMID: 35290609 PMCID: PMC9226254 DOI: 10.1007/s13311-022-01217-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [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] [Accepted: 03/07/2022] [Indexed: 12/16/2022] Open
Abstract
Hypoxic-ischemic (HI) brain injury is a major contributor to neurodevelopmental morbidities. Inter-alpha inhibitor proteins (IAIPs) have neuroprotective effects on HI-related brain injury in neonatal rats. However, the effects of treatment with IAIPs on sequential behavioral, MRI, and histopathological abnormalities in the young adult brain after treatment with IAIPs in neonates remain to be determined. The objective of this study was to examine the neuroprotective effects of IAIPs at different neurodevelopmental stages from newborn to young adults after exposure of neonates to HI injury. IAIPs were given as 11-sequential 30-mg/kg doses to postnatal (P) day 7-21 rats after right common carotid artery ligation and exposure to 90 min of 8% oxygen. The resulting brain edema and injury were examined by T2-weighted magnetic resonance imaging (MRI) and cresyl violet staining, respectively. The mean T2 values of the ipsilateral hemisphere from MRI slices 6 to 10 were reduced in IAIP-treated HI males + females on P8, P9, and P10 and females on P8, P9, P10, and P14. IAIP treatment reduced hemispheric volume atrophy by 44.5 ± 29.7% in adult male + female P42 rats and improved general locomotor abilities measured by the righting reflex over time at P7.5, P8, and P9 in males + females and males and muscle strength/endurance measured by wire hang on P16 in males + females and females. IAIPs provided beneficial effects during the learning phase of the Morris water maze with females exhibiting beneficial effects. IAIPs confer neuroprotection from HI-related brain injury in neonates and even in adult rats and beneficial MRI and behavioral benefits in a sex-dependent manner.
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Affiliation(s)
- Xiaodi Chen
- Department of Pediatrics, Infants Hospital of Rhode Island, Warren Alpert Medical School of Brown University, Women &101 Dudley Street, Providence, RI, 02905-2499, USA
| | - Jiyong Zhang
- Department of Pediatrics, Infants Hospital of Rhode Island, Warren Alpert Medical School of Brown University, Women &101 Dudley Street, Providence, RI, 02905-2499, USA
| | - Yuqi Wu
- Department of Pediatrics, Infants Hospital of Rhode Island, Warren Alpert Medical School of Brown University, Women &101 Dudley Street, Providence, RI, 02905-2499, USA
| | - Richard Tucker
- Department of Pediatrics, Infants Hospital of Rhode Island, Warren Alpert Medical School of Brown University, Women &101 Dudley Street, Providence, RI, 02905-2499, USA
| | - Grayson L Baird
- Department of Diagnostic Imaging, Biostatistics Core Lifespan Hospital System, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, RI, USA
| | - Rose Domonoske
- Department of Pediatrics, Infants Hospital of Rhode Island, Warren Alpert Medical School of Brown University, Women &101 Dudley Street, Providence, RI, 02905-2499, USA
| | - Adriel Barrios-Anderson
- Department of Pediatrics, Infants Hospital of Rhode Island, Warren Alpert Medical School of Brown University, Women &101 Dudley Street, Providence, RI, 02905-2499, USA
| | - Yow-Pin Lim
- ProThera Biologics, Inc, Providence, RI, USA
- Department of Pathology and Laboratory Medicine, Warren Alpert Medical School of Brown University, Providence, RI, USA
| | - Kevin Bath
- Division of Developmental Neuroscience, New York State Psychiatric Institute, New York, NY, USA
- Department of Psychiatry, Columbia University Irving Medical College, New York, NY, USA
| | - Edward G Walsh
- Department of Neuroscience, Brown University, Providence, RI, USA
| | - Barbara S Stonestreet
- Department of Pediatrics, Infants Hospital of Rhode Island, Warren Alpert Medical School of Brown University, Women &101 Dudley Street, Providence, RI, 02905-2499, USA.
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White TL, Gonsalves MA, Cohen RA, Harris AD, Monnig MA, Walsh EG, Nitenson AZ, Porges EC, Lamb DG, Woods AJ, Borja CB. The neurobiology of wellness: 1H-MRS correlates of agency, flexibility and neuroaffective reserves in healthy young adults. Neuroimage 2020; 225:117509. [PMID: 33127477 PMCID: PMC7869459 DOI: 10.1016/j.neuroimage.2020.117509] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [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: 06/18/2020] [Revised: 10/08/2020] [Accepted: 10/21/2020] [Indexed: 02/06/2023] Open
Abstract
Proton magnetic resonance spectroscopy (1H-MRS) is a noninvasive imaging technique that measures the concentration of metabolites in defined areas of the human brain in vivo. The underlying structure of natural metabolism-emotion relationships is unknown. Further, there is a wide range of between-person differences in metabolite concentration in healthy individuals, but the significance of this variation for understanding emotion in healthy humans is unclear. Here we investigated the relationship of two emotional constructs, agency and flexibility, with the metabolites glutamate and glutamine (Glx), N-acetylaspartate (tNAA), choline (Cho), creatine (tCr), and myo-inositol (Ins) in the right dorsal anterior cingulate cortex (dACC) in medically and psychiatrically healthy volunteers (N = 20, 9 female; mean age = 22.8 years, SD = 3.40). The dACC was selected because this region is an integrative hub involved in multiple brain networks of emotion, cognition and behavior. Emotional traits were assessed using the Multidimensional Personality Questionnaire Brief Form (MPQ-BF), an empirically derived self-report instrument with an orthogonal factor structure. Phenotypes evaluated were positive and negative agency (MPQ-BF Social Potency, Aggression), emotional and behavioral flexibility (MPQ-BF Absorption, Control-reversed), and positive and negative affect (MPQ-BF Social Closeness; Stress Reaction, Alienation). The resting concentration of tNAA in the dACC was robustly positively correlated with Absorption (r = +0.56, unadjusted p = .005), moderately positively correlated with Social Potency (r = +0.42, unadjusted p = .03), and robustly negatively correlated with Aggression (r = −0.59, unadjusted p = .003). Absorption and Aggression accounted for substantial variance in tNAA (R2 = 0.31, 0.35; combined R2 = 0.50), and survived correction for multiple comparisons (Holm-Bonferroni adjusted p = .032, 0.021, respectively). dACC Glx and Cho had modest relationships with behavioral flexibility and social affiliation that did not survive this multiple correction, providing effect sizes for future work. Principal Component Analysis (PCA) revealed a three-factor orthogonal solution indicating specific relationships between: 1) Glx and behavioral engagement; 2) Cho and affiliative bonding; and 3) tNAA and a novel dimension that we term neuroaffective reserves. Our results inform the neurobiology of agency and flexibility and lay the groundwork for understanding mechanisms of natural emotion using 1H-MRS.
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Affiliation(s)
- Tara L White
- Center for Alcohol and Addiction Studies, Brown University, Box G-S121-4, 121 South Main St., Providence, RI 02912, USA; Department of Behavioral and Social Sciences, School of Public Health, Brown University, Providence, RI, USA; Carney Institute for Brain Science, Brown University, Providence, RI, USA.
| | | | - Ronald A Cohen
- Department of Clinical and Health Psychology, Center for Cognitive Aging and Memory, and McKnight Brain Research Foundation, University of Florida, Gainesville, FL, USA
| | - Ashley D Harris
- Department of Radiology, CAIR Program, Alberta Children's Hospital Research Institute, and Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
| | - Mollie A Monnig
- Center for Alcohol and Addiction Studies, Brown University, Box G-S121-4, 121 South Main St., Providence, RI 02912, USA
| | - Edward G Walsh
- Department of Neuroscience, Brown University, Providence, RI, USA
| | - Adam Z Nitenson
- Neuroscience Graduate Program, Brown University, Providence, RI, USA
| | - Eric C Porges
- Department of Clinical and Health Psychology, Center for Cognitive Aging and Memory, and McKnight Brain Research Foundation, University of Florida, Gainesville, FL, USA
| | - Damon G Lamb
- Department of Psychiatry, and Center for Cognitive Aging and Memory, McKnight Brain Research Foundation, University of Florida, Gainesville, FL, USA; Center for Neuropsychological Studies, Department of Neurology, University of Florida College of Medicine, Gainesville, FL, USA; Brain Rehabilitation Research Center, Malcom Randall Veterans Affairs Medical Center, Gainesville, FL, USA
| | - Adam J Woods
- Department of Clinical and Health Psychology, Center for Cognitive Aging and Memory, and McKnight Brain Research Foundation, University of Florida, Gainesville, FL, USA
| | - Cara B Borja
- Neuroscience Graduate Program, Brown University, Providence, RI, USA
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10
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Maxwell AWP, Park WKC, Baird GL, Walsh EG, Dupuy DE. Adjuvant Thermal Accelerant Gel Use Increases Microwave Ablation Zone Temperature in Porcine Liver as Measured by MR Thermometry. J Vasc Interv Radiol 2020; 31:1357-1364. [PMID: 32457010 DOI: 10.1016/j.jvir.2020.01.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 12/23/2019] [Accepted: 01/12/2020] [Indexed: 12/14/2022] Open
Abstract
PURPOSE To determine the effects of a thermal accelerant gel on temperature parameters during microwave liver ablation. MATERIALS AND METHODS Sixteen consecutive liver ablations were performed in 5 domestic swine under general anesthesia with (n = 8) and without (n = 8) administration of thermal accelerant gel. Ablation zone temperature was assessed by real-time MR thermometry, measured as maximum temperature (Tmax) and the volume of tissue ≥ 60°C (V60). Tissue heating rate, ablation zone shape, and thermal energy deposition using the temperature degree-minutes at 43°C (TDM43) index were also measured. Differences between groups were analyzed using generalized mixed modeling with significance set at P = .05. RESULTS Mean peak ablation zone temperature was significantly greater with thermal accelerant use (mean Tmax, thermal accelerant: 120.0°C, 95% confidence interval [CI] 113.0°C-126.9°C; mean Tmax, control: 80.3°C, 95% CI 72.7°C-88.0°C; P < .001), and a significantly larger volume of liver tissue achieved or exceeded 60°C when thermal accelerant was administered (mean V60, thermal accelerant: 22.2 cm3; mean V60, control: 15.9 cm3; P < .001). Significantly greater thermal energy deposition was observed during ablations performed with accelerant (mean TDM43, thermal accelerant: 198.4 min, 95% CI 170.7-230.6 min; mean TDM43, control: 82.8 min, 95% CI 80.5-85.1 min; P < .0001). The rate of tissue heating was significantly greater with thermal accelerant use (thermal accelerant: 5.8 min ± 0.4; control: 10.0 min; P < .001), and accelerant gel ablations demonstrated a more spherical temperature distribution (P = .002). CONCLUSIONS Thermal accelerant use is associated with higher microwave ablation zone temperatures, greater thermal energy deposition, and faster and more spherical tissue heating compared with control ablations.
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Affiliation(s)
- Aaron W P Maxwell
- The Warren Alpert Medical School of Brown University, 593 Eddy Street, Providence, RI 02903.
| | - William K C Park
- The Warren Alpert Medical School of Brown University, 593 Eddy Street, Providence, RI 02903
| | - Grayson L Baird
- The Warren Alpert Medical School of Brown University, 593 Eddy Street, Providence, RI 02903
| | - Edward G Walsh
- The Warren Alpert Medical School of Brown University, 593 Eddy Street, Providence, RI 02903
| | - Damian E Dupuy
- The Warren Alpert Medical School of Brown University, 593 Eddy Street, Providence, RI 02903
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11
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Tamaki M, Wang Z, Barnes-Diana T, Yamada T, Walsh EG, Watanabe T, Sasaki Y. Different but complementary roles of NREM and REM sleep in facilitation of visual perceptual learning associated with neurotransmitters changes revealed by magnetic resonance spectroscopy. J Vis 2019. [DOI: 10.1167/19.10.29c] [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: 11/24/2022] Open
Affiliation(s)
- Masako Tamaki
- Department of Cognitive, Linguistic and Psychological Sciences, Brown University
| | - Zhiyan Wang
- Department of Cognitive, Linguistic and Psychological Sciences, Brown University
| | - Tyler Barnes-Diana
- Department of Cognitive, Linguistic and Psychological Sciences, Brown University
| | - Takashi Yamada
- Department of Cognitive, Linguistic and Psychological Sciences, Brown University
| | - Edward G Walsh
- Department of Cognitive, Linguistic and Psychological Sciences, Brown University
| | - Takeo Watanabe
- Department of Cognitive, Linguistic and Psychological Sciences, Brown University
| | - Yuka Sasaki
- Department of Cognitive, Linguistic and Psychological Sciences, Brown University
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12
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Bang JW, Shibata K, Frank SM, Walsh EG, Greenlee MW, Watanabe T, Sasaki Y. Consolidation and reconsolidation share behavioral and neurochemical mechanisms. Nat Hum Behav 2018; 2:507-513. [PMID: 30505952 PMCID: PMC6258036 DOI: 10.1038/s41562-018-0366-8] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Accepted: 05/18/2018] [Indexed: 12/24/2022]
Affiliation(s)
- Ji Won Bang
- Department of Cognitive, Linguistic, and Psychological Sciences, Brown University, Providence, RI, USA
- Department of Ophthalmology, School of Medicine, New York University, New York, NY, USA
| | - Kazuhisa Shibata
- Department of Cognitive, Linguistic, and Psychological Sciences, Brown University, Providence, RI, USA
- Department of Cognitive and Psychological Sciences, Graduate School of Informatics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya City, Japan
| | - Sebastian M Frank
- Department of Cognitive, Linguistic, and Psychological Sciences, Brown University, Providence, RI, USA
- Institute for Experimental Psychology, University of Regensburg, Regensburg, Germany
| | - Edward G Walsh
- Department of Neuroscience, Brown University, Providence, RI, USA
| | - Mark W Greenlee
- Institute for Experimental Psychology, University of Regensburg, Regensburg, Germany
| | - Takeo Watanabe
- Department of Cognitive, Linguistic, and Psychological Sciences, Brown University, Providence, RI, USA.
- Department of Neuroscience, Brown University, Providence, RI, USA.
| | - Yuka Sasaki
- Department of Cognitive, Linguistic, and Psychological Sciences, Brown University, Providence, RI, USA
- Department of Neuroscience, Brown University, Providence, RI, USA
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13
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Beveridge JE, Machan JT, Walsh EG, Kiapour AM, Karamchedu NP, Chin KE, Proffen BL, Sieker JT, Murray MM, Fleming BC. Magnetic resonance measurements of tissue quantity and quality using T 2 * relaxometry predict temporal changes in the biomechanical properties of the healing ACL. J Orthop Res 2018; 36:1701-1709. [PMID: 29227559 PMCID: PMC5995620 DOI: 10.1002/jor.23830] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Accepted: 12/04/2017] [Indexed: 02/04/2023]
Abstract
The purpose of this study was to develop a magnetic resonance T2 * relaxometry-based multiple linear regression model to predict the structural properties of the healing anterior cruciate ligament (ACL) over a 24-week healing period following ACL repair in Yucatan minipigs. Two hypotheses were tested: (i) that a regression model based on ACL sub-volumes containing short and long T2 * relaxation times would outperform a competing model based on sub-volumes of short T2 * relaxation times only; and (ii) that an optimized regression model would be capable of predicting ACL structural properties between 6 and 24 weeks post-repair. ACLs were imaged in 24 minipigs (8/group) at either 6, 12, or 24 weeks after ACL repair. The structural properties of the ACLs were determined from tensile failure tests. Four multiple linear regression models of increasing complexity were fitted to the data. Akaike Information Criterion values and Bland-Altman tests were used to compare model performance and to test the hypotheses. The structural properties predicted from the multiple linear regression model that was based on the change in ACL sub-volumes of both the short and long T2 * relaxation times over the healing period were in closest agreement to the measured values, suggesting that the amounts of both organized and disorganized collagen, and the change in these quantities over time, are required to predict the structural properties of healing ACLs accurately. CLINICAL SIGNIFICANCE our time-specific, T2 *-based regression model may allow us to estimate the structural properties of ACL repairs in vivo longitudinally. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1701-1709, 2018.
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Affiliation(s)
- Jillian E Beveridge
- Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, Rhode Island
| | - Jason T Machan
- Rhode Island Hospital Biostatistics Core, Providence, Rhode Island
| | - Edward G Walsh
- Division of Biology and Medicine, Department of Neuroscience, Brown University, Providence, Rhode Island
| | | | - Naga Padmini Karamchedu
- Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, Rhode Island
| | - Kaitlyn E Chin
- Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, Rhode Island
| | | | | | | | - Braden C Fleming
- Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, Rhode Island
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14
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Shibata K, Sasaki Y, Bang JW, Walsh EG, Machizawa MG, Tamaki M, Chang LH, Watanabe T. Corrigendum: Overlearning hyperstabilizes a skill by rapidly making neurochemical processing inhibitory-dominant. Nat Neurosci 2017; 20:1427. [PMID: 28949333 DOI: 10.1038/nn1017-1427b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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15
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Shibata K, Sasaki Y, Bang JW, Walsh EG, Machizawa MG, Tamaki M, Chang LH, Watanabe T. Overlearning hyperstabilizes a skill by rapidly making neurochemical processing inhibitory-dominant. Nat Neurosci 2017; 20:470-475. [PMID: 28135242 PMCID: PMC5323354 DOI: 10.1038/nn.4490] [Citation(s) in RCA: 104] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 01/04/2017] [Indexed: 12/17/2022]
Abstract
Overlearning refers to the continued training of a skill after performance improvement has plateaued. Whether overlearning is beneficial is a question in our daily lives that has never been clearly answered. Here, we report a new important role: Overlearning abruptly changes neurochemical processing to hyper-stabilize and protect trained perceptual learning from subsequent new learning. Usually, learning immediately after training is so unstable that it can be disrupted by subsequent new learning, unless waiting for passive stabilization, which takes hours. However, overlearning so rapidly and strongly stabilizes the learning state that it not only becomes resilient against, but disrupts, subsequent new learning. Such hyper-stabilization is associated with an abrupt shift from glutamate-dominant excitatory to gamma-aminobutyric-acid-dominant inhibitory processing in early visual areas. Hyper-stabilization contrasts with passive and slower stabilization, which is associated with a mere reduction of an excitatory dominance to baseline levels. Utilizing hyper-stabilization may lead to efficient learning paradigms.
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Affiliation(s)
- Kazuhisa Shibata
- Department of Cognitive, Linguistics, &Psychological Sciences, Brown University, Providence, Rhode Island, USA.,Graduate School of Environmental Studies, Nagoya University, Nagoya, Japan
| | - Yuka Sasaki
- Department of Cognitive, Linguistics, &Psychological Sciences, Brown University, Providence, Rhode Island, USA
| | - Ji Won Bang
- Department of Cognitive, Linguistics, &Psychological Sciences, Brown University, Providence, Rhode Island, USA
| | - Edward G Walsh
- Department of Neuroscience, Brown University, Providence, Rhode Island, USA
| | - Maro G Machizawa
- Department of Cognitive, Linguistics, &Psychological Sciences, Brown University, Providence, Rhode Island, USA
| | - Masako Tamaki
- Department of Cognitive, Linguistics, &Psychological Sciences, Brown University, Providence, Rhode Island, USA
| | - Li-Hung Chang
- Department of Cognitive, Linguistics, &Psychological Sciences, Brown University, Providence, Rhode Island, USA
| | - Takeo Watanabe
- Department of Cognitive, Linguistics, &Psychological Sciences, Brown University, Providence, Rhode Island, USA
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16
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Affiliation(s)
- E G Walsh
- Department of Physiology, University Medical School, Edinburgh
| | - M Lakie
- Department of Physiology, University Medical School, Edinburgh
| | - G W Wright
- Department of Physiology, University Medical School, Edinburgh
| | - S A Tsementzis
- Department of Surgical Neurology, Western General Hospital, Edinburgh
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17
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Biercevicz AM, Proffen BL, Murray MM, Walsh EG, Fleming BC. T2* relaxometry and volume predict semi-quantitative histological scoring of an ACL bridge-enhanced primary repair in a porcine model. J Orthop Res 2015; 33:1180-7. [PMID: 25764143 PMCID: PMC4497917 DOI: 10.1002/jor.22874] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [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: 12/10/2014] [Accepted: 02/16/2015] [Indexed: 02/04/2023]
Abstract
Magnetic resonance imaging (MRI) variables, such as T2* and volume, can predict the healing ligament structural properties. How these MR variables relate to semi-quantitative histology of the healing ACL is yet unknown. We hypothesized that T2* and volume would predict the histological scoring of a healing ACL. Yucatan minipigs underwent ACL transection and received bridge-enhanced ACL repair or no treatment. The surgical legs were harvested after 52 weeks and imaged using a high resolution 2-echo sequence. For each ligament, the volume and median T2* values were determined. The ACL specimens were then histologically analyzed using the advanced Ligament Maturity Index (LMI). The T2* of the healing ligaments significantly predicted the total LMI score as well as the cell, collagen and vessel sub-scores; R(2) = 0.78, 0.67, 0.65, and 0.60, respectively (p ≤ 0.001). The ligament volume also predicted the total LMI score, cell, and collagen sub-scores; R(2) = 0.39, 0.33, 0.37, and 0.60, respectively (p ≤ 0.001). A lower ligament T2* or a higher volume was associated with higher histological scores of the healing ligaments. This study provides a critical step in the development of a non-invasive method to evaluate ligament healing on a microscopic scale.
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Affiliation(s)
- Alison M. Biercevicz
- Department of Orthopaedics, Warren Alpert Medical School, Brown University/Rhode Island Hospital, Providence RI,School of Engineering, Brown University, Providence, RI
| | | | - Martha M. Murray
- Dept of Orthopaedic Surgery, Children's Hospital Boston, Boston MA
| | - Edward G. Walsh
- Department of Neuroscience, Division of Biology and Medicine, Brown University, Providence, RI
| | - Braden C. Fleming
- Department of Orthopaedics, Warren Alpert Medical School, Brown University/Rhode Island Hospital, Providence RI,School of Engineering, Brown University, Providence, RI
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18
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Biercevicz AM, Akelman MR, Rubin LE, Walsh EG, Merck D, Fleming BC. The uncertainty of predicting intact anterior cruciate ligament degeneration in terms of structural properties using T(2)(*) relaxometry in a human cadaveric model. J Biomech 2015; 48:1188-92. [PMID: 25746575 DOI: 10.1016/j.jbiomech.2015.02.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [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: 11/20/2014] [Revised: 01/15/2015] [Accepted: 02/15/2015] [Indexed: 11/26/2022]
Abstract
The combination of healing anterior cruciate ligament (ACL) volume and the distributions of T2(*) relaxation times within it have been shown to predict the biomechanical failure properties in a porcine model. This MR-based prediction model has not yet been used to assess ligament degeneration in the aging human knee. Using a set of 15 human cadaveric knees of varying ages, we obtained in situ MR measures of volume and T2(*) of the intact ACL and then related these MR variables to biomechanical outcomes (maximum and yield loads, linear stiffness) obtained via ex vivo failure testing. Using volume in conjunction with the median T2(*) value, the multiple linear regression model did not predict maximum failure load for the intact human ACL; R(2)=0.23, p=0.200. Similar insignificant results were found for yield load and linear stiffness. Naturally restricted distributions of the intact ligament volume and T2(*) (demonstrated by the respective Z-scores) in an older cadaveric population were the likely reason for the insignificant results. These restricted distributions may negatively affect the ability to detect a correlation when one exists. Further research is necessary to understand the relationship of MRI variables and ligament degeneration. While this study failed to find a significant prediction of human biomechanical outcome using these MR variables, with further research, an MR-based approach may offer a tool to longitudinally assess changes in cruciate ligament degradation.
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Affiliation(s)
- A M Biercevicz
- Department of Orthopaedics, Warren Alpert Medical School, Brown University/Rhode Island Hospital, Providence, RI, USA; Center for Biomedical Engineering and School of Engineering, Brown University, Providence, RI, USA
| | - M R Akelman
- Department of Orthopaedics, Warren Alpert Medical School, Brown University/Rhode Island Hospital, Providence, RI, USA
| | - L E Rubin
- Department of Orthopaedics, Warren Alpert Medical School, Brown University/Rhode Island Hospital, Providence, RI, USA
| | - E G Walsh
- Department of Neuroscience, Division of Biology and Medicine, Brown University, Providence, RI, USA
| | - D Merck
- Center for Biomedical Engineering and School of Engineering, Brown University, Providence, RI, USA; Department of Diagnostic Imaging, Warren Alpert Medical School of Brown University/Rhode Island Hospital, Providence, RI, USA
| | - B C Fleming
- Department of Orthopaedics, Warren Alpert Medical School, Brown University/Rhode Island Hospital, Providence, RI, USA; Center for Biomedical Engineering and School of Engineering, Brown University, Providence, RI, USA.
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Abstract
Innovations that improve sensitivity and reduce cost are of paramount importance in diagnostic imaging. The novel x-ray imaging modality called spatial frequency heterodyne imaging (SFHI) is based on a linear arrangement of x-ray source, tissue, and x-ray detector, much like that of a conventional x-ray imaging apparatus. However, SFHI rests on a complete paradigm reversal compared to conventional x-ray absorption-based radiology: while scattered x-rays are carefully rejected in absorption-based x-ray radiology to enhance the image contrast, SFHI forms images exclusively from x-rays scattered by the tissue. In this study we use numerical processing to produce x-ray scatter images of hepatocellular carcinoma labeled with a nanoparticle contrast agent. We subsequently compare the sensitivity of SFHI in this application to that of both conventional x-ray imaging and magnetic resonance imaging (MRI). Although SFHI is still in the early stages of its development, our results show that the sensitivity of SFHI is an order of magnitude greater than that of absorption-based x-ray imaging and approximately equal to that of MRI. As x-ray imaging modalities typically have lower installation and service costs compared to MRI, SFHI could become a cost effective alternative to MRI, particularly in areas of the world with inadequate availability of MRI facilities.
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Affiliation(s)
- Danielle Rand
- Department of Chemistry, Brown University. 324 Brook Street, Providence, Rhode Island 02912 (USA)
| | - Edward G. Walsh
- Department of Neuroscience, Brown University. 185 Meeting Street, Providence, Rhode Island 02912 (USA)
| | - Zoltan Derdak
- The Liver Research Center, Rhode Island Hospital and Warren Alpert Medical School of Brown University. 55 Claverick Street, Providence, Rhode Island 02903 (USA)
| | - Jack R. Wands
- The Liver Research Center, Rhode Island Hospital and Warren Alpert Medical School of Brown University. 55 Claverick Street, Providence, Rhode Island 02903 (USA)
| | - Christoph Rose-Petruck
- Department of Chemistry, Brown University. 324 Brook Street, Providence, Rhode Island 02912 (USA)
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20
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Menon RG, Walsh EG, Twieg DB, Cantrell CG, Vakil P, Jonathan SV, Batjer HH, Carroll TJ. Snapshot MR technique to measure OEF using rapid frequency mapping. J Cereb Blood Flow Metab 2014; 34:1111-6. [PMID: 24756077 PMCID: PMC4083374 DOI: 10.1038/jcbfm.2014.59] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [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: 11/17/2013] [Accepted: 03/12/2014] [Indexed: 11/09/2022]
Abstract
Magnetic resonance (MR)-based oxygen extraction fraction (OEF) measurement techniques that use blood oxygen level-dependent (BOLD)-based approaches require the measurement of the R2' decay rate and deoxygenated blood volume to derive the local oxygen saturation in vivo. We describe here a novel approach to measure OEF using rapid local frequency mapping. By modeling the MR decay process in the static dephasing regime as two separate dissipative and oscillatory effects, we calculate the OEF from local frequencies measured across the brain by assuming that the biophysical mechanisms causing OEF-related frequency changes can be determined from the oscillatory effects. The Parameter Assessment by Retrieval from Signal Encoding (PARSE) technique was used to acquire the local frequency change maps. The PARSE images were taken on 11 normal volunteers, and 1 patient exhibiting hemodynamic stress. The mean MR-OEF in 11 normal subjects was 36.66±7.82%, in agreement with positron emission tomography (PET) literature. In regions of hemodynamic stress induced by vascular steal, OEF exhibits the predicted focal increases. These preliminary results show that it is possible to measure OEF using a rapid frequency mapping technique. Such a technique has numerous advantages including speed of acquisition, is noninvasive, and has sufficient spatial and temporal resolution.
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Affiliation(s)
- Rajiv G Menon
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Edward G Walsh
- Department of Neuroscience, Brown University, Providence, Rhode Island, USA
| | - Donald B Twieg
- Deparment of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Charles G Cantrell
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Parmede Vakil
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Sumeeth V Jonathan
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Hunt H Batjer
- Department of Neurosurgery, UT Southwestern, Dallas, Texas, USA
| | - Timothy J Carroll
- 1] Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA [2] Department of Biomedical Engineering, Northwestern University, Chicago, IL, USA
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21
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Alosco ML, Gunstad J, Xu X, Clark US, Labbe DR, Riskin-Jones HH, Terrero G, Schwarz NF, Walsh EG, Poppas A, Cohen RA, Sweet LH. The impact of hypertension on cerebral perfusion and cortical thickness in older adults. ACTA ACUST UNITED AC 2014; 8:561-70. [PMID: 25151318 DOI: 10.1016/j.jash.2014.04.002] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [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: 02/25/2014] [Revised: 03/23/2014] [Accepted: 04/07/2014] [Indexed: 12/25/2022]
Abstract
Hypertension may increase risk for dementia possibly because of its association with decreased cortical thickness. Disturbed cerebral autoregulation is one plausible mechanism by which hypertension impacts the cerebral structure, but the associations among hypertension, brain perfusion, and cortical thickness are poorly understood. The current sample consisted of 58 older adults with varying levels of vascular disease. Diagnostic history of hypertension and antihypertensive medication status was ascertained through self-report, and when available, confirmed by medical record review. All participants underwent arterial spin labeling and T1-weighted magnetic resonance imaging to quantify total and regional cortical perfusion and thickness. Analysis of covariance adjusting for medical variables showed that participants with hypertension exhibited reduced temporal and occipital brain perfusion and total and regional cortical thickness relative to those without hypertension. The effects of hypertension on total brain perfusion remained unchanged even after adjustment for age, although no such pattern emerged for cortical thickness. Decreased total brain perfusion predicted reduced thickness of the total brain and of the frontal, temporal, and parietal lobe cortices. Antihypertensive treatment was not associated with total cerebral perfusion or cortical thickness. This study provides initial evidence for the adverse effects of a diagnostic history of hypertension on brain hypoperfusion and reduced cortical thickness. Longitudinal studies are needed to investigate the role of hypertension and its interaction with other contributing factors (e.g., age) in the manifestation of cerebral hypoperfusion and reduced cortical thickness.
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Affiliation(s)
| | - John Gunstad
- Department of Psychology, Kent State University, Kent, OH, USA
| | - Xiaomeng Xu
- Department of Psychology, Idaho State University, Pocatello, ID, USA
| | - Uraina S Clark
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Donald R Labbe
- Alpert Medical School of Brown University, the Department of Psychiatry and Human Behavior, Providence, RI, USA
| | - Hannah H Riskin-Jones
- Brain Behavior and Aging Research Center, VA Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | - Gretel Terrero
- Alpert Medical School of Brown University, Providence, RI, USA
| | | | - Edward G Walsh
- Brown University, Departments of Neuroscience and Diagnostic Imaging., Providence, RI, USA
| | - Athena Poppas
- Alpert Medical School of Brown University, Department of Medicine, Providence, RI, USA
| | - Ronald A Cohen
- Cognitive Aging and Memory Program, Clinical Translational Research Program, Institute on Aging, University of Florida, Gainesville, FL, USA
| | - Lawrence H Sweet
- Alpert Medical School of Brown University, the Department of Psychiatry and Human Behavior, Providence, RI, USA; Department of Psychology, University of Georgia, Athens, GA, USA
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Biercevicz AM, Walsh EG, Murray MM, Akelman MR, Fleming BC. Improving the clinical efficiency of T2(*) mapping of ligament integrity. J Biomech 2014; 47:2522-5. [PMID: 24792580 DOI: 10.1016/j.jbiomech.2014.03.037] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [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: 12/31/2013] [Revised: 03/21/2014] [Accepted: 03/22/2014] [Indexed: 10/25/2022]
Abstract
Current MR methods use T2(*) relaxation time as a surrogate measure of ligament strength. Currently, a multi-echo voxel-wise least squares fit is the gold standard to create T2(*) maps; however, the post-processing is time-intensive and serves as a stopgap for clinical use. The study objective was to determine if an alternative method could improve post-processing time without sacrificing fidelity of T2(*) values for eventual translational use in the clinic. Using a 6 echo FLASH sequence, three different methods were used to determine intact posterior cruciate ligament (PCL) median T2(*) Two of these methods utilized a voxel-wise method to establish T2(*) maps: (1) a current "gold standard" method using a voxel-wise 6 echo least-squares fit (6LS) and (2) a voxel-wise 2 echo point T2(*) determination (2MM). The third method used median ligament signal intensity and a single nonlinear least-squares fit (6LSROI) instead of a voxel-wise basis. The resulting median T2(*) values of the PCL and computational time were compared. The median T2(*) values were 42% higher using the 2MM compared to the 6LS method (p<0.0001). However, a strong correlation was found for the median T2(*) values between the 2MM and 6LS methods (R(2)=0.80). The median T2(*) values were not significantly different between the 6LS and 6LSROI methods (p=0.519). Using the 2MM (which provides a regional map) and the 6LSROI (which efficiently provides the median T2(*) value) methods in tandem would take only minutes of post-processing computational time compared to the 6LS method (~540 min), and hence would facilitate clinical application of T2(*) maps to predict ligament structural properties as a patient outcome measure.
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Affiliation(s)
- A M Biercevicz
- Department of Orthopaedics, Warren Alpert Medical School, Brown University, 1 Hoppin St, Coro West, Ste 404, Providence, RI 02903, USA
| | - E G Walsh
- Department of Neuroscience, Division of Biology and Medicine, Brown University, Providence, RI, USA
| | - M M Murray
- Department of Orthopaedic Surgery, Children׳s Hospital Boston, Boston, MA, USA
| | - M R Akelman
- Department of Orthopaedics, Warren Alpert Medical School, Brown University, 1 Hoppin St, Coro West, Ste 404, Providence, RI 02903, USA
| | - B C Fleming
- Department of Orthopaedics, Warren Alpert Medical School, Brown University, 1 Hoppin St, Coro West, Ste 404, Providence, RI 02903, USA.
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Biercevicz AM, Murray MM, Walsh EG, Miranda DL, Machan JT, Fleming BC. T2 * MR relaxometry and ligament volume are associated with the structural properties of the healing ACL. J Orthop Res 2014; 32:492-9. [PMID: 24338640 PMCID: PMC3946219 DOI: 10.1002/jor.22563] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [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: 07/16/2013] [Accepted: 11/19/2013] [Indexed: 02/04/2023]
Abstract
Our objective was to develop a non-invasive magnetic resonance (MR) method to predict the structural properties of a healing anterior cruciate ligament (ACL) using volume and T2 * relaxation time. We also compared our T2 *-based structural property prediction model to a previous model utilizing signal intensity, an acquisition-dependent variable. Surgical ACL transection followed by no treatment (i.e., natural healing) or bio-enhanced ACL repair was performed in a porcine model. After 52 weeks of healing, high-resolution MR images of the ACL tissue were collected. From these images, ligament volumes and T2 * maps were established. The structural properties of the ligaments were determined via tensile testing. Using the T2 * histogram profile, each ligament voxel was binned based on its T2 * value into four discrete tissue sub-volumes defined by specific T2 * intervals. The linear combination of the ligament sub-volumes binned by T2 * value significantly predicted maximum load, yield load, and linear stiffness (R(2) = 0.92, 0.82, 0.88; p < 0.001) and were similar to the previous signal intensity based method. In conclusion, the T2 * technique offers a highly predictive methodology that is a first step towards the development of a method that can be used to assess ligament healing across scanners, studies, and institutions.
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Affiliation(s)
- Alison M. Biercevicz
- Department of Orthopaedics, Warren Alpert Medical School, Brown University/Rhode Island Hospital, Providence, RI
| | - Martha M. Murray
- Department of Orthopaedic Surgery, Boston Children's Hospital, Boston, MA
| | - Edward G. Walsh
- Department of Neuroscience, Division of Biology and Medicine, Brown University, Providence, RI
| | - Danny L. Miranda
- Department of Orthopaedics, Warren Alpert Medical School, Brown University/Rhode Island Hospital, Providence, RI
| | - Jason T. Machan
- Department of Orthopaedics, Warren Alpert Medical School, Brown University/Rhode Island Hospital, Providence, RI,Biostatistics, Rhode Island Hospital, Providence, RI
| | - Braden C. Fleming
- Department of Orthopaedics, Warren Alpert Medical School, Brown University/Rhode Island Hospital, Providence, RI,School of Engineering, Brown University, Providence, RI 02903
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Alosco ML, Gunstad J, Jerskey BA, Xu X, Clark US, Hassenstab J, Cote DM, Walsh EG, Labbe DR, Hoge R, Cohen RA, Sweet LH. The adverse effects of reduced cerebral perfusion on cognition and brain structure in older adults with cardiovascular disease. Brain Behav 2013; 3:626-36. [PMID: 24363966 PMCID: PMC3868168 DOI: 10.1002/brb3.171] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Revised: 06/30/2013] [Accepted: 08/11/2013] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND It is well established that aging and vascular processes interact to disrupt cerebral hemodynamics in older adults. However, the independent effects of cerebral perfusion on neurocognitive function among older adults remain poorly understood. We examined the associations among cerebral perfusion, cognitive function, and brain structure in older adults with varying degrees of vascular disease using perfusion magnetic resonance imaging (MRI) arterial spin labeling (ASL). MATERIALS AND METHODS 52 older adults underwent neuroimaging and were administered the Mini Mental State Examination (MMSE), the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), and measures of attention/executive function. ASL and T1-weighted MRI were used to quantify total brain perfusion, total brain volume (TBV), and cortical thickness. RESULTS Regression analyses showed reduced total brain perfusion was associated with poorer performance on the MMSE, RBANS total index, immediate and delayed memory composites, and Trail Making Test B. Reduced frontal lobe perfusion was associated with worse executive and memory function. A similar pattern emerged between temporal lobe perfusion and immediate memory. Regression analyses revealed that decreased total brain perfusion was associated with smaller TBV and mean cortical thickness. Regional effects of reduced total cerebral perfusion were found on temporal and parietal lobe volumes and frontal and temporal cortical thickness. DISCUSSION Reduced cerebral perfusion is independently associated with poorer cognition, smaller TBV, and reduced cortical thickness in older adults. CONCLUSION Prospective studies are needed to clarify patterns of cognitive decline and brain atrophy associated with cerebral hypoperfusion.
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Affiliation(s)
| | - John Gunstad
- Department of Psychology, Kent State University Kent, Ohio
| | - Beth A Jerskey
- Department of Psychiatry and Human Behavior, Alpert Medical School of Brown University Providence, Rhode Island
| | - Xiaomeng Xu
- Department of Psychology, Idaho State University Pocatello, Idaho
| | - Uraina S Clark
- Department of Neurology, Icahn School of Medicine at Mount Sinai New York, NY
| | - Jason Hassenstab
- Department of Neurology, Washington University at St. Louis St. Louis, Missouri
| | | | - Edward G Walsh
- Department of Neuroscience, Brown University Providence, Rhode Island
| | - Donald R Labbe
- Department of Psychiatry and Human Behavior, Alpert Medical School of Brown University Providence, Rhode Island
| | - Richard Hoge
- Department of Physiology, Université de Montréal Montréal, Quebec, Canada
| | - Ronald A Cohen
- Department of Psychiatry and Human Behavior, Alpert Medical School of Brown University Providence, Rhode Island ; Center for Cognitive Aging and Memory, McKnight Brain Institute, University of Florida Gainesville, Florida
| | - Lawrence H Sweet
- Department of Psychiatry and Human Behavior, Alpert Medical School of Brown University Providence, Rhode Island ; Butler Hospital Providence, Rhode Island ; Department of Psychology, University of Georgia Athens, Georgia
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Mills DR, Walsh EG, Brilliant KE, Hixson DC, Park WK. A Targeted Iron‐based MRI Contrast for Tumor Detection. FASEB J 2013. [DOI: 10.1096/fasebj.27.1_supplement.1088.6] [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: 11/11/2022]
Affiliation(s)
- David R. Mills
- MedicineRhode Island Hospital/Brown UniversityProvidenceRI
| | | | | | | | - William K.C. Park
- Diagnostic ImagingRhode Island Hospital/Brown UniversityProvidenceRI
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26
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Menon RG, Walsh EG, Sutton BP, Twieg DB, Cantrell CG, Vakil P, Jonathan SV, Prabhakaran S, Carroll TJ. Abstract WP228: Measurement Of Oxygen Extraction Fraction (OEF) By A Novel MRI Technique. Stroke 2013. [DOI: 10.1161/str.44.suppl_1.awp228] [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] [Indexed: 11/16/2022]
Abstract
We report a novel application of an MRI technique called Parameter Assessment by Retrieval from Signal Encoding (PARSE) to measure OEF. OEF is of crucial importance, providing information about the stage of neurovascular impairment in a patient and the risk of stroke in such a patient. In this study, we test the hypothesis that PARSE can be used to measure oxygen extraction in the brain. This method uses a more accurate MR signal model, employs a non-Cartesian Rosette trajectory to encode multiple parameters and can simultaneously estimate M
0
, R
2
*, and local frequency in a single, non-invasive 5 second acquisition. Of particular interest here, is the feasibility to directly measure susceptibility related frequency changes from local frequency estimates. Since OEF abnormalities are focal, contralateral measurements were used to estimate the relative frequency change. We acquired data on 5 human subjects. In the series of 5 normal volunteers (M/F 3/2, <age> = 26 +/-10 years) we acquired a single slice, 5.0 mm thick, 220 mm x 220 mm FOV, 64 x 64 matrix, image resolution = 3 x 3 x 5.0 mm
3
) 2D PARSE images. The total sequence time was 5 seconds. One arterio-venous malformation (AVM) patient was also tested with the PARSE-OEF sequence. The parameters were identical to the volunteer scans. For the 5 volunteers, the average frequency change (δω) across the brain image slice was 15.49 Hz ±2.77 Hz. This corresponded to an average whole brain-slice OEF of 37.23 ± 6.60%. This is in agreement with gold-standard Positron Emission Tomography (PET) OEF studies of normative values from Carpenter (35±7%), Yamauchi (42±5%), Diringer (41±6%) and Raichle (40±9%). Our current values are in excellent agreement with PET literature values. Upon further validation, this technique may be a viable clinical alternative to PET-OEF.
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27
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Mohan HM, Collins D, Maher S, Walsh EG, Winter DC, O'Brien PJ, Brayden DJ, Baird AW. The mycotoxin patulin increases colonic epithelial permeability in vitro. Food Chem Toxicol 2012; 50:4097-102. [PMID: 22906760 DOI: 10.1016/j.fct.2012.07.036] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 07/18/2012] [Accepted: 07/19/2012] [Indexed: 01/11/2023]
Abstract
The gastrointestinal lumen is directly exposed to dietary contaminants, including patulin, a mycotoxin produced by moulds. Patulin is known to increase permeability across intestinal Caco-2 monolayers. This study aimed to determine the effect of patulin on permeability, ion transport and morphology in isolated rat colonic mucosae. Mucosal sheets were mounted in Ussing chambers and voltage clamped. Apical addition of patulin (100-500 μM) rapidly reduced transepithelial electrical resistance (TEER) and increased permeability to [(14)C] mannitol (2.9-fold). Patulin also inhibited carbachol-induced electrogenic chloride secretion and histological evidence of mucosal damage was observed. To examine potential mechanisms of action of patulin on colonic epithelial cells, high-content analysis of Caco-2 cells was performed and this novel, quantitative fluorescence-based approach confirmed its cytotoxic effects. With regard to time course, the cytotoxicity determined by high content analysis took longer than the almost immediate reduction of electrical resistance in isolated mucosal sheets. These data indicate patulin is not only cytotoxic to enterocytes but also has the capacity to directly alter permeability and ion transport in intact intestinal mucosae. These data corroborate and extend findings in intestinal cell culture monolayers, and further suggest that safety limits on consumption of patulin may be warranted.
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Affiliation(s)
- H M Mohan
- UCD School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland
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Walsh EG, Brott BC, Johnson VY, Venugopalan R, Anayiotos A. Assessment of passive cardiovascular implant devices for MRI compatibility. Technol Health Care 2008. [DOI: 10.3233/thc-2008-16401] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Edward G. Walsh
- Department of Neuroscience, Brown University, Providence, RI, USA
| | - Brigitta C. Brott
- Division of Cardiovascular Disease, University of Alabama at Birmingham, AL, USA
| | - Vicki Y. Johnson
- Department of Biomedical Engineering, University of Alabama at Birmingham, AL, USA
- School of Nursing, University of Alabama at Birmingham, AL, USA
| | | | - Andreas Anayiotos
- Department of Biomedical Engineering, University of Alabama at Birmingham, AL, USA
- Department of Mechanical and Materials Engineering, Cyprus University of Technology, Limassol, Cyprus
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Xu C, Xie J, Kohler N, Walsh EG, Chin YE, Sun S. Monodisperse magnetite nanoparticles coupled with nuclear localization signal peptide for cell-nucleus targeting. Chem Asian J 2008; 3:548-552. [PMID: 18080259 DOI: 10.1002/asia.200700301] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Functionalization of monodisperse superparamagnetic magnetite (Fe(3)O(4)) nanoparticles for cell specific targeting is crucial for cancer diagnostics and therapeutics. Targeted magnetic nanoparticles can be used to enhance the tissue contrast in magnetic resonance imaging (MRI), to improve the efficiency in anticancer drug delivery, and to eliminate tumor cells by magnetic fluid hyperthermia. Herein we report the nucleus-targeting Fe(3)O(4) nanoparticles functionalized with protein and nuclear localization signal (NLS) peptide. These NLS-coated nanoparticles were introduced into the HeLa cell cytoplasm and nucleus, where the particles were monodispersed and non-aggregated. The success of labeling was examined and identified by fluorescence microscopy and MRI. The work demonstrates that monodisperse magnetic nanoparticles can be readily functionalized and stabilized for potential diagnostic and therapeutic applications.
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Affiliation(s)
- Chenjie Xu
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA, Fax: (+1) 401-863-9046
| | - Jin Xie
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA, Fax: (+1) 401-863-9046
| | - Nathan Kohler
- Brown Medical School, Brown University, Providence, Rhode Island 02906, USA
| | - Edward G Walsh
- Department of Neuroscience, Brown University, Providence, Rhode Island 02912, USA
| | - Y Eugene Chin
- Department of Surgery, School of Medicine, Brown University, Providence, Rhode Island 02903, USA
| | - Shouheng Sun
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA, Fax: (+1) 401-863-9046
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30
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Affiliation(s)
- Chenjie Xu
- Department of Chemistry, Brown University, Providence, RI 02912, USA
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31
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Walsh EG, Brott BC, Johnson VY, Venugopalan R, Anayiotos A. Assessment of passive cardiovascular implant devices for MRI compatibility. Technol Health Care 2008; 16:233-245. [PMID: 18776600] [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]
Abstract
PURPOSE The increasing popularity of both magnetic resonance angiography and minimally invasive cardiovascular interventional procedures has led to the requirement for the development of implant devices that not only provide for patient safety, but produce minimal artifacts in diagnostic images. The purpose of this paper is to assess and discuss physical principles and ASTM testing standards related to the MRI compatibility of implanted devices. ANALYSIS AND REVIEW OF IMAGING COMPATIBILITY AND SAFETY OF COMMON IMPLANTS AND DEVICES Standard procedures are described to assess safety and ability to image near implanted stents and heart valves made from different materials and of varying geometry. MRI physical principles, material properties and MR simulations are discussed in the context of estimation of ferromagnetic force, displacement, torque, tissue heating, susceptibility artifacts, and radiofrequency shielding in cardiovascular stents and heart valves during MR imaging. CONCLUSION MRI compatibility is a function of both material composition and device geometry. MR-safe devices are available that provide for reduced image artifacts over stainless-steel devices.
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Affiliation(s)
- Edward G Walsh
- Department of Neuroscience, Brown University, Providence, RI, USA
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33
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Zuo J, Walsh EG, Twieg DB. Flow SS-PARSE: a new method for rapid imaging and mapping of blood flow velocity. Conf Proc IEEE Eng Med Biol Soc 2007; 2006:530-3. [PMID: 17271730 DOI: 10.1109/iembs.2004.1403211] [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] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
A new method for flow velocity mapping of blood is presented here. Instead of the conventional approach of employing two images (velocity sensitive and control) to generate velocity information, in the new method the velocity is determined directly by solving an inverse problem. This technique is an application of single shot - parameter assessment by retrieval from signal encoding (SS-PARSE). Simulations have been done to demonstrate the feasibility of the method. The velocity measurement range of the prototype version is from -50cm/s to 50cm/s, roughly appropriate for future applications in blood flow measurement of carotid arteries.
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Affiliation(s)
- J Zuo
- Dept. of Biomedical Eng., Alabama Univ., Birmingham, AL, USA
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34
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Abstract
A new method for flow velocity mapping is presented here. Instead of the conventional approach of employing two images (velocity sensitive and control) to generate velocity information, in the new method one determines the velocity directly from a single-shot acquisition by solving an inverse problem. This technique is a variant of single-shot parameter assessment by retrieval from signal encoding (SS-PARSE). The results of simulation and phantom studies show strong agreement with the actual velocities. The prototype method can measure velocities in the range of -50 to 50 cm/s, which is roughly appropriate for future applications in dynamic blood flow measurement in carotid arteries.
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Affiliation(s)
- Jin Zuo
- Department of Biomedical Engineering, University of Alabama at Birmingham, USA.
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35
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Johnson VY, Walsh EG. Nurses making a difference: the process of technology transfer. J Neurosci Nurs 2005; 37:289-92. [PMID: 16379136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Affiliation(s)
- Vicki Y Johnson
- The University of Alabama School of Nursing, Birmingham, USA.
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36
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Holton AD, Walsh EG, Brott BC, Venugopalan R, Hershey B, Ito Y, Shih A, Koomullil R, Anayiotos AS. Evaluation of in-stent stenosis by magnetic resonance phase-velocity mapping in nickel-titanium stents. J Magn Reson Imaging 2005; 22:248-57. [PMID: 16028256 DOI: 10.1002/jmri.20380] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
PURPOSE To evaluate different grades of in-stent stenosis in a nickel-titanium stent with MRI. MATERIALS AND METHODS Magnetic resonance phase velocity mapping (MR-PVM) was used to measure flow velocity through a 9-mm NiTi stent with three different degrees of stenosis in a phantom study. The tested stenotic geometries were 1) axisymmetric 75%, 2) axisymmetric 90%, and 3) asymmetric 50%. The MR-PVM data were subsequently compared with the velocities from computational fluid dynamic (CFD) simulations of identical conditions. RESULTS Good quantitative agreement in velocity distribution for the 50% and 75% stenoses was observed. The agreement was poor for the 90% stenosis, most likely due to turbulence and the high-velocity gradients found in the small luminal area relative to the pixel resolution in our imaging settings. CONCLUSION The accuracy of the MRI velocities inside the stented area renders MRI a modality that may be used to assess moderate to severe in-stent restenosis (ISR) in medium-sized vascular stents in peripheral vessels, such as the iliac, carotid, and femoral arteries. Advances in MR instrumentation may provide sufficient resolution to obtain adequate velocity information from smaller vessels, such as the coronary arteries, and allow MRI to substitute for invasive and expensive catheterization procedures currently in clinical use.
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Affiliation(s)
- Andrea D Holton
- Department of Biomedical Engineering, University of Alabama at Birmingham, 1075 13th Street South, Birmingham, AL 35294-4440, USA
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37
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Walsh EG, Holton AD, Brott BC, Venugopalan R, Anayiotos AS. Magnetic resonance phase velocity mapping through NiTi stents in a flow phantom model. J Magn Reson Imaging 2004; 21:59-65. [PMID: 15611949 DOI: 10.1002/jmri.20238] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
PURPOSE To assess constant and pulsatile flow velocity within the lumen of a peripheral NiTi stent using phase velocity mapping for comparison with independent assessments of flow velocity in a phantom model. MATERIALS AND METHODS A 9 x 20-mm stent installed in flexible tubing was placed in a phantom filled with stationary fluid. Constant and pulsatile flow (produced by a pump programmed to produce a simulation of the carotid artery flow) was assessed using phase velocity mapping at 4.1 T (for constant flow) and at 1.5 T (for pulsatile flow). In all cases 256 x 256 gradient echo phase velocity maps were acquired. For the pulsatile flow condition, cine images with acquisition gated to the pump cycle were acquired with 40 msec temporal resolution across the simulated cardiac cycle. Computed flow volume rates were compared with fluid volume collection for the constant flow model, and with ultrasonic Doppler flow meter measurements for the pulsatile model. RESULTS The data showed that volume flow rate assessments by phase velocity mapping agreed with independent measurements within 10% to 15%. CONCLUSION Phase velocity mapping of the lumen of peripheral size NiTi stents is possible in an in vitro model.
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Affiliation(s)
- Edward G Walsh
- Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, Alabama, USA
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38
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Doyle M, Fuisz A, Kortright E, Biederman RW, Walsh EG, Martin ET, Tauxe L, Rogers WJ, Merz CN, Pepine C, Sharaf B, Pohost GM. The impact of myocardial flow reserve on the detection of coronary artery disease by perfusion imaging methods: an NHLBI WISE study. J Cardiovasc Magn Reson 2003; 5:475-85. [PMID: 12882078 DOI: 10.1081/jcmr-120022263] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.2] [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: 11/03/2022] Open
Abstract
Myocardial flow reserve (MFR) is not routinely assessed in myocardial perfusion imaging (MPI) studies but has been hypothesized to affect test accuracy when assessing disease severity by coronary vessel lumenography. Magnetic resonance imaging (MRI) is an emerging diagnostic technique that can both perform MPI and assess MFR. We studied women (n = 184) enrolled in the Women's Ischemia Syndrome Evaluation (WISE) study with symptoms suggesting ischemic heart disease. Tests performed were coronary angiography and MPI by both MR and gated radionuclide single photon emission computed tomography (gated-SPECT). The MFR index was calculated using the MR data acquired at baseline and under vasodilation (dipyridamole) conditions. The study was structured with a pilot and an implementation phase. During the pilot phase (n = 46) data were unmasked and an MFR threshold was defined to divide patients into those with an adequate (AMFRI) or inadequate (IMFRI) MFR index. During the implementation phase, the MFR index threshold was prospectively applied to patients (n = 138). In the implementation phase, MPI ischemia detection accuracy compared to severe (> or = 70%) coronary artery diameter narrowing by angiography was higher in the AMFRI vs. the IMFRI group for MRI (86% vs. 70%, p < 0.05) and gated-SPECT (89% vs. 67%, p < 0.01). The IMFRI group (n = 55, 30% of study population) had a higher resting rate-pressure product compared with the AMFRI group (10,599 +/- 2871 vs. 9378 +/- 2447 bpm mm Hg, p < 0.01), consistent with higher resting myocardial flow. When compared with each other, MRI and gated-SPECT MPI showed no difference in accuracy among MFR groups. Myocardial perfusion patterns in the IMFRI group may have resulted in atypical perfusion patterns, which either masked or mimicked epicardial coronary artery disease.
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Affiliation(s)
- Mark Doyle
- Division of Cardiovascular Diseases, Department of Medicine, University of Alabama at Birmingham, D201J Diabetes Education and Research Building, 1808 Seventh Avenue South, Birmingham, Alabama 35294-0012, USA.
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39
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Masi AT, Walsh EG. Ankylosing spondylitis: integrated clinical and physiological perspectives. Clin Exp Rheumatol 2003; 21:1-8. [PMID: 12673883] [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: 03/01/2023]
Abstract
This hypothesis paper draws upon clinical epidemiological and physiological perspectives of axial muscle tone relevant to ankylosing spondylitis (AS). Skeletal muscle tonus is the property of intrinsic tension or resistance to stretch with no additional muscle contraction. The interpretations call attention to novel concepts of the intrinsic axial muscular system contributions to enthesopathic lesions in AS. The axial kinematic chain extends from the entire spine to the posterior aspects of the lower extremities and is essential for postural and mobility functions. Muscles and articular cartilage derive from common embryological precursor cells and are complexly coordinated in the maintenance of postures and dynamic functions. A definitive link between axial muscular dysfunction and respective joint pathology has not yet been demonstrated in AS. However, the following clinical epidemiological and physiological observations raise the possibility of a relationship between axial muscular hypertonicity and AS, which will be reviewed sequentially.
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Affiliation(s)
- A T Masi
- Department of Medicine, University of Illinois College of Medicine at Peoria (UICOMP), One Illini Drive, Box 1649, Peoria, Illinois 61656-1649, USA.
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40
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Walsh EG, Anayiotos A, Doyle M, Pohost GM. Effect of contrast agent viscosity and injection flow velocity on bolus injection pressures for peripheral venous injection in first-pass myocardial perfusion studies. Technol Health Care 2002. [DOI: 10.3233/thc-2002-10106] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Edward G. Walsh
- Department of Biomedical Engineering, University of Alabama, Birmingham, AL, USA
| | - Andreas Anayiotos
- Department of Biomedical Engineering, University of Alabama, Birmingham, AL, USA
| | - Mark Doyle
- Department of Medicine, Division of Cardiovascular Disease, University of Alabama, Birmingham, AL, USA
| | - Gerald M. Pohost
- Department of Medicine, Division of Cardiovascular Disease, University of Alabama, Birmingham, AL, USA
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Walsh EG, Anayiotos A, Doyle M, Pohost GM. Effect of contrast agent viscosity and injection flow velocity on bolus injection pressures for peripheral venous injection in first-pass myocardial perfusion studies. Technol Health Care 2002; 10:57-63. [PMID: 11847448 DOI: 10.1046/j.0966-0410.2001.00340.x-i3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/17/2023]
Abstract
Myocardial perfusion imaging using Gd contrast agents is typically performed with bolus injections of the contrast agent using a power injector to provide for consistent and sufficiently rapid injection rates for all patients. For protocols in which a peripheral venous injection is called for (e.g. antecubital vein) injection catheters of 18 ga are used where vessel geometry permits. In some patients, particularly women with smaller veins, 20 and 22 ga catheters are used. The effect of catheter size and pressure tubing length can result in high injection pressures that occasionally cause leakage or connector failure. The viscosity of the contrast agent also impacts injection pressure. In this study, a simulation of the injection pathway was constructed with time resolved pressures measured at two points in the pathway. Pressure drops were calculated for a typical MR perfusion injection protocol.
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Affiliation(s)
- Edward G Walsh
- Department of Biomedical Engineering, University of Alabama, Birmingham, AL 35294-4440, USA.
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Abstract
Velocity-encoded cine (VEC) imaging is potentially an important clinical diagnostic technique for cardiovascular diseases. Advances in gradient technology combined with segmentation approaches have made possible breathhold VEC imaging, allowing data to be obtained free of respiratory artifacts. However, when using conventional segmentation approaches, spatial and temporal resolutions are typically compromised to accommodate short breathhold times. Here we apply a sparse sampling technique, turbo-BRISK (i.e., segmented block regional interpolation scheme for k-space) to VEC imaging, allowing increased spatial and temporal resolution to be obtained in a short breathhold period. BRISK is a sparse sampling technique with interpolation used to generate unsampled data. BRISK was implemented to reduce the scan time by 70% compared with a conventional scan. Further, turbo-BRISK scans, using segmentation factors up to 5, reduce the scan time by up to 94%. Phantom and in vivo results are presented that demonstrate the accuracy of turbo-BRISK VEC imaging. In vitro validation is performed using conventional magnetic resonance VEC. Pulsatile centerline flow velocity measurements obtained with turbo-BRISK acquisitions were correlated with conventional magnetic resonance imaging measurements and achieved r values of 0.99 +/- 0.004 (mean +/- SD) with stroke volumes agreeing to within 4%. A potential limitation of BRISK is reduced accuracy for rapidly varying velocity profiles. We present low- and high-resolution data sets to illustrate the resolution dependence of this phenomenon and demonstrate that at conventional resolutions, turbo-BRISK can accurately represent rapid velocity changes. In vivo results indicate that centerline velocity waveforms in the descending aorta correlate well with conventional measurements with an average r value of 0.98 +/- 0.01.
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Affiliation(s)
- M Doyle
- Department of Medicine, Division of Cardiovascular Disease, University of Alabama at Birmingham, Birmingham, Alabama, USA
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Walsh EG, Doyle M, Kortright ME, Straeter-Knowlen IM, Pohost GM. Recent progress in radiofrequency-tagged left ventricular function studies. J Cardiovasc Magn Reson 2001; 1:185-93. [PMID: 11550352 DOI: 10.3109/10976649909080848] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- E G Walsh
- Department of Medicine, Division of Cardiovascular Disease, University of Alabama at Birmingham School of Medicine, Birmingham, Alabama, USA
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Anayiotos AS, Kortright E, Doyle M, Walsh EG, Fuisz AR, Pohost GM. Hemodynamic evaluation with TURBO BRISK--a rapid phase contrast angiography technique. Technol Health Care 2001; 8:327-42. [PMID: 11258579] [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: 02/19/2023]
Abstract
Hemodynamic imaging by phase contrast angiography was significantly accelerated by selective interpolation and segmentation in k-space using TURBO BRISK. The method was tested in vitro on three independent flowfields, representative of human blood rheology: a straight tube simulating the descending aorta, a curved tube simulating the aortic arch and a two-chamber orifice flow model simulating valvular regurgitation. The results were compared to data obtained by Laser Doppler Velocimetry (LDV) and showed good agreement. For the straight tube, the flow velocity obtained by five TURBO BRISK methods with increasing segmentation factors and corresponding time savings showed good agreement with LDV. For the curved tube, the velocity showed good general agreement with some differences in the decelerating part of the cycle, and in the low-velocity secondary flow structures. The orifice flow evaluation, the most time consuming case, was performed by the control volume method. It showed good agreement with actual flows through the orifice. Data acquisitions for TURBO-4 BRISK could be performed in 20s for each velocity component. The method shows promise for breath-hold acquisitions in clinical applications, including calculation of blood flow volumes through diseased arteries, measurement of blood backflow volumes through dysfunctional heart valves to time valve replacement operations, and evaluation of arterial wall shear stress, an important factor in the genesis of atherosclerosis.
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Affiliation(s)
- A S Anayiotos
- Biomedical Engineering Department, University of Alabama at Birmingham, 35294-4440, USA.
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Butterworth EJ, Walsh EG, Hugg JW. A TiO(2) dielectric filled toroidal radio frequency cavity resonator for high-field NMR. NMR Biomed 2001; 14:184-191. [PMID: 11357183 DOI: 10.1002/nbm.693] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
R(F) performance in high-field MRI applications is improved by filling the resonator with material of relative dielectric constant approximating that of human soft tissue. We demonstrate this by filling a toroidal cavity resonator operating in TEM(00) (cyclotron) mode with titanium dioxide (TiO(2)) in powdered rutile form, and acquiring phantom, human lower leg and human breast images of good quality at 4.1 T. Images made with this resonator had unusually high SNR, while the level of R(f) power required to produce a 90 degrees flip angle pulse was about a quartes as high for the filled resonator as for the same resonator before filling. Phantom images obtained with the filled resonator had an SNR of nearly 300 at a resolution of 256 x 256 voxels, nearly three times that of images of the same phantom obtained using a standard volume R(f) coil in frequent use at this laboratory. Breast images made at 256 x 256 voxels resolution had an SNR of 174, also unusually high for a volume coil. High-resolution (512 x 512 voxels) were also obtained, with SNR = 60. Preliminary phantom and in vivo human images are presented in this article. Acquiring the phantom and leg images required significantly less R(f) power than did comparable imaging using a conventional coil. In addition, the field lines were focused as they penetrated into the sample, and this resulted in a more homogeneous B(1)-field. We believe that these improvements occurred because the dielectric presence minimizes the large dielectric mismatch between air and sample.
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Affiliation(s)
- E J Butterworth
- Department of Biomedical Engineering and Center for Nuclear Imaging Research, University of Alabama at Birmingham, 828 Eighth Court South, Birmingham, AL 35294-4470, USA.
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Kortright E, Doyle M, Anayiotos AS, Walsh EG, Fuisz AR, Pohost GM. Validation of rapid velocity encoded cine imaging of a dynamically complex flow field using turbo block regional interpolation scheme for k space. Ann Biomed Eng 2001; 29:128-34. [PMID: 11284667 DOI: 10.1114/1.1349702] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Block regional interpolation scheme for k space (BRISK) is a sparse sampling approach to allow rapid magnetic resonance imaging of dynamic events. Rapid velocity encoded cine (VEC) imaging with Turbo BRISK is potentially an important clinical diagnostic technique for cardiovascular diseases. Previously we applied BRISK and Turbo BRISK to imaging pulsatile flow in a straight tube. To evaluate the capabilities of Turbo BRISK imaging in more complex dynamic flow fields such as might exist in the human vasculature, an in vitro curved tube model, similar in geometry to the aortic arch, was fabricated and imaged under pulsatile flow conditions. Velocity maps were obtained using conventional VEC and Turbo BRISK (turbo factors 1 through 5). Comparison of the flow fields obtained with each higher order turbo factor showed excellent agreement with conventional VEC with minimal loss of information. Similarly, flow maps showed good agreement with the profiles from a laser Doppler velocimetry model. Turbo-5 BRISK, for example, allowed a 94% savings in imaging time, reducing the conventional imaging time from over 8 min to a near breath-hold imaging period of 31 s. Turbo BRISK shows excellent promise toward the development of a clinical tool to evaluate complex dynamic intravascular flow fields.
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Affiliation(s)
- E Kortright
- Computer Science Department, University of New Orleans, LA 70148, USA.
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Anayiotos AS, Kortright E, Doyle M, Walsh EG, Fuisz AR, M. Pohost G. Hemodynamic evaluation with TURBO BRISK – a rapid phase contrast angiography technique. Technol Health Care 2000. [DOI: 10.3233/thc-2000-8602] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Andreas S. Anayiotos
- Biomedical Engineering Department, University of Alabama at Birmingham, Birmingham, AL 35294-4440, USA
| | - Eduardo Kortright
- Computer Science Department, University of New Orleans, Lakefront Campus, New Orleans, LA 70148, USA
| | - Mark Doyle
- Center of Nuclear Magnetic Resonance, Division of Cardiovascular Disease, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Edward G. Walsh
- Biomedical Engineering Department, University of Alabama at Birmingham, Birmingham, AL 35294-4440, USA
| | - Anthon R. Fuisz
- Center of Nuclear Magnetic Resonance, Division of Cardiovascular Disease, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Gerald M. Pohost
- Center of Nuclear Magnetic Resonance, Division of Cardiovascular Disease, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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Lin JP, Brown JK, Walsh EG. Continuum of reflex excitability in hemiplegia: influence of muscle length and muscular transformation after heel-cord lengthening and immobilization on the pathophysiology of spasticity and clonus. Dev Med Child Neurol 1999; 41:534-48. [PMID: 10479042 DOI: 10.1017/s0012162299001152] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The electromyographic (EMG) responses to tendon taps at the ankle and ensuing muscular twitch forces and temporal parameters were studied at varying angles across the joint range in 18 children, aged 3 to 14.9 years, with congenital hemiparetic cerebral palsy and 22 healthy (control) children, aged 3 to 13.6 years. Those subjects with hemiparesis were community ambulators without assistance. In all subjects, passive muscle stretch caused a waxing of the reflex EMG and twitch force near neutral (with the sole of the foot at right angles to the tibia) and a diminution of these with further dorsiflexion. Twitch times increased with each dorsiflexing increment, being slowest at maximum dorsiflexion and fastest at the resting plantarflexion angle. Heterogeneity of the hemiparetic-limb data is evident when compared with data of non-paretic and unaffected limbs, with clear differences in the clonic (fast twitch) as opposed to non-clonic (slow twitch) muscles. In four cases with clinical clonus, clonus frequency was reduced by passive dorsiflexion. Plaster immobilization for 1 month produced clonus which was previously absent in one subject, and caused a fast-twitch phenotype to emerge in two subjects. Follow-up after heel-cord lengthening in one subject showed that clonus frequency diminished from 9 to 3 Hz with slowing and strengthening of muscle-twitch phenotype. Short- and long-term peripheral manipulations appear to regulate neuromuscular excitability according to whether muscles are loaded or unloaded. Although damage to the nervous system provides the setting for reflex excitability, the data suggest that the muscle length (which specifies the joint angle) and the muscle-twitch phenotype of any given limb for any given case appear to dictate the actual speed and strength of reflex muscle-twitch and clonus profiles. This study illustrates how peripheral manipulations of muscles and tendons may alter the expression of what have hitherto been considered as exclusively central phenomena.
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Affiliation(s)
- J P Lin
- One Small Step Gait and Movement Laboratory, Guy's and St Thomas' Hospital Trust, London, UK.
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Reis SE, Holubkov R, Lee JS, Sharaf B, Reichek N, Rogers WJ, Walsh EG, Fuisz AR, Kerensky R, Detre KM, Sopko G, Pepine CJ. Coronary flow velocity response to adenosine characterizes coronary microvascular function in women with chest pain and no obstructive coronary disease. Results from the pilot phase of the Women's Ischemia Syndrome Evaluation (WISE) study. J Am Coll Cardiol 1999; 33:1469-75. [PMID: 10334410 DOI: 10.1016/s0735-1097(99)00072-8] [Citation(s) in RCA: 148] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
OBJECTIVES We sought to develop and validate a definition of coronary microvascular dysfunction in women with chest pain and no significant epicardial obstruction based on adenosine-induced changes in coronary flow velocity (i.e., coronary velocity reserve). BACKGROUND Chest pain is frequently not caused by fixed obstructive coronary artery disease (CAD) of large vessels in women. Coronary microvascular dysfunction is an alternative mechanism of chest pain that is more prevalent in women and is associated with attenuated coronary volumetric flow augmentation in response to hyperemic stimuli (i.e., abnormal coronary flow reserve). However, traditional assessment of coronary volumetric flow reserve is time-consuming and not uniformly available. METHODS As part of the Women's Ischemia Syndrome Evaluation (WISE) study, 48 women with chest pain and normal coronary arteries or minimal coronary luminal irregularities (mean stenosis = 7%) underwent assessment of coronary blood flow reserve and coronary flow velocity reserve. Blood flow responses to intracoronary adenosine were measured using intracoronary Doppler ultrasonography and quantitative angiography. RESULTS Coronary volumetric flow reserve correlated with coronary velocity reserve (Pearson correlation = 0.87, p < 0.001). In 29 (60%) women with abnormal coronary microcirculation (mean coronary flow reserve = 1.84), adenosine increased coronary velocity by 89% (p < 0.001) but did not change coronary cross-sectional area. In 19 (40%) women with normal microcirculation (mean flow reserve = 3.24), adenosine increased coronary velocity and area by 179% (p < 0.001) and 17% (p < 0.001), respectively. A coronary velocity reserve threshold of 2.24 provided the best balance between sensitivity and specificity (90% and 89%, respectively) for the diagnosis of microvascular dysfunction. In addition, failure of the epicardial coronary to dilate at least 9% was found to be a sensitive (79%) and specific (79%) surrogate marker of microvascular dysfunction. CONCLUSIONS Coronary flow velocity response to intracoronary adenosine characterizes coronary microvascular function in women with chest pain in the absence of obstructive CAD. Attenuated epicardial coronary dilation response to adenosine may be a surrogate marker of microvascular dysfunction in women with chest pain and no obstructive CAD.
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Affiliation(s)
- S E Reis
- Department of Medicine, University of Pittsburgh, Pennsylvania, USA.
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Lin JP, Brown JK, Walsh EG. Soleus muscle length, stretch reflex excitability, and the contractile properties of muscle in children and adults: a study of the functional joint angle. Dev Med Child Neurol 1997; 39:469-80. [PMID: 9285438 DOI: 10.1111/j.1469-8749.1997.tb07467.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The influence of the joint angle on stretch reflex excitability of the soleus muscle at the ankle has been studied in 22 children aged 3.9 to 13.6 years and 9 adults aged 19 to 70 years. For all subjects, reflex EMG and mechanical twitch torque gain were trivial at resting plantar flexion. The reflex EMG gain reached a maximum between -15 degrees and -10 degrees of plantar flexion beyond the neutral angle, 0 degrees, defined as the foot at right angle to the tibia, diminishing steeply with further dorsiflexion. The reflex mechanical gain rose to a peak between 0 degrees and +10 degrees of dorsiflexion beyond neutral, declining steeply thereafter. By contrast, axonally stimulated muscle twitch torque increased serially up to +30 degrees dorsiflexion beyond neutral. For the soleus muscle, the optimal reflex neuromechanical angle lies approximately midway between the angle for optimal reflex EMG gain (in mild plantar flexion, at which the largest and strongest motor units can be activated) and the optimal muscle mechanical angle (at the extreme of soleus muscle dorsiflexion). These studies confirm that the excitability of the spinal alpha motor neuron pool in vivo is strongly influenced by muscle length and explain the variability in reflex excitability within and between subjects, if the joint angle is not controlled. They also indicate how posture influences movement, agreeing with the known function of the soleus muscle in the stance phase of gait and the modulation of motor unit recruitment during voluntary alternating movements at the ankle. Soleus muscle twitch characteristics show a fivefold to eightfold increase in peak force associated with a tenfold reduction in compliance in the first two decades of life and an apparent speeding up of twitch time in the first decade.
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Affiliation(s)
- J P Lin
- 'One Small Step' Gait and Movement Laboratory and the Newcomen Centre, Guy's Hospital, London. UK
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