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Nyman JS, Ketsiri T, Louie EA, Harkins KD, Manhard MK, Gochberg DF, Lee DH, Desai MJ, Maslow J, Tanner SB, Does MD. Toward the use of MRI measurements of bound and pore water in fracture risk assessment. Bone 2023; 176:116863. [PMID: 37527697 PMCID: PMC10528882 DOI: 10.1016/j.bone.2023.116863] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [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: 06/07/2023] [Revised: 07/26/2023] [Accepted: 07/28/2023] [Indexed: 08/03/2023]
Abstract
The current clinical assessment of fracture risk lacks information about the inherent quality of a person's bone tissue. Working toward an imaging-based approach to quantify both a bone tissue quality marker (tissue hydration as water bound to the matrix) and a bone microstructure marker (porosity as water in pores), we hypothesized that the concentrations of bound water (Cbw) are lower and concentrations of pore water (Cpw) are higher in patients with osteoporosis (OP) than in age- and sex-matched adults without the disease. Using recent developments in ultrashort echo time (UTE) magnetic resonance imaging (MRI), maps of Cbw and Cpw were acquired from the uninjured distal third radius (Study 1) of 20 patients who experienced a fragility fracture of the distal radius (Fx) and 20 healthy controls (Non-Fx) and from the tibia mid-diaphysis (Study 2) of 30 women with clinical OP (low T-scores) and 15 women without OP (normal T-scores). In Study 1, Cbw was significantly lower (p = 0.0018) and Cpw was higher (p = 0.0022) in the Fx than in the Non-Fx group. In forward stepwise, logistic regression models using Bayesian Information Criterion for selecting the best set of predictors (from imaging parameters, age, BMI, and DXA scanner type), the area-under-the-receiver operator characteristics-curve (AUC with 95 % confidence intervals) was 0.73 (0.56, 0.86) for hip aBMD (best predictors without MRI) and 0.86 (0.70, 0.95) for the combination of Cbw and Cpw (best predictors overall). In Study 2, Cbw was significantly lower (p = 0.0005) in women with OP (23.8 ± 4.3 1H mol/L) than in women without OP (29.9 ± 6.4 1H mol/L); Cpw was significantly higher by estimate of 2.9 1H mol/L (p = 0.0298) with clinical OP, but only when accounting for the type of UTE-MRI scan with 3D providing higher values than 2D (p < 0.0001). Lastly, Cbw, but not Cpw, was sensitive to bone forming osteoporosis medications over 12-months. UTE-MRI-derived measurements of bound and pore water concentrations are potential, aBMD-independent predictors of fracture risk.
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Affiliation(s)
- Jeffry S Nyman
- Department of Orthopaedic Surgery, Vanderbilt University Medical Center, 1215 21st Ave. S., Suite 4200, Nashville, TN 37232, USA; Department of Biomedical Engineering, Vanderbilt University, 5824 Stevenson Center, Nashville, TN 37232, USA; Department of Veterans Affairs, Tennessee Valley Healthcare System, 1310 24th Ave. S., Nashville, TN 37212, USA; Vanderbilt Center for Bone Biology, Vanderbilt University Medical Center,1211 Medical Center Dr., Nashville, TN 37212, USA.
| | - Thammathida Ketsiri
- Department of Biomedical Engineering, Vanderbilt University, 5824 Stevenson Center, Nashville, TN 37232, USA; Institute of Imaging Science, Vanderbilt University Medical Center, 1161 21st Ave. S., Nashville, TN 37232, USA
| | - Elizabeth A Louie
- Institute of Imaging Science, Vanderbilt University Medical Center, 1161 21st Ave. S., Nashville, TN 37232, USA
| | - Kevin D Harkins
- Department of Biomedical Engineering, Vanderbilt University, 5824 Stevenson Center, Nashville, TN 37232, USA; Institute of Imaging Science, Vanderbilt University Medical Center, 1161 21st Ave. S., Nashville, TN 37232, USA; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, 1161 21st Ave. S., Nashville, TN 37232, USA
| | - Mary Kate Manhard
- Imaging Research Center, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave, Cincinnati, OH 45229, USA
| | - Daniel F Gochberg
- Institute of Imaging Science, Vanderbilt University Medical Center, 1161 21st Ave. S., Nashville, TN 37232, USA; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, 1161 21st Ave. S., Nashville, TN 37232, USA
| | - Donald H Lee
- Department of Orthopaedic Surgery, Vanderbilt University Medical Center, 1215 21st Ave. S., Suite 4200, Nashville, TN 37232, USA
| | - Mihir J Desai
- Department of Orthopaedic Surgery, Vanderbilt University Medical Center, 1215 21st Ave. S., Suite 4200, Nashville, TN 37232, USA
| | - Jed Maslow
- Department of Orthopaedic Surgery, Vanderbilt University Medical Center, 1215 21st Ave. S., Suite 4200, Nashville, TN 37232, USA
| | - S Bobo Tanner
- Vanderbilt Center for Bone Biology, Vanderbilt University Medical Center,1211 Medical Center Dr., Nashville, TN 37212, USA; Department of Medicine, Division of Rheumatology, Vanderbilt University Medical Center, 1161 21st Ave. S., Nashville, TN 37232, USA
| | - Mark D Does
- Department of Biomedical Engineering, Vanderbilt University, 5824 Stevenson Center, Nashville, TN 37232, USA; Institute of Imaging Science, Vanderbilt University Medical Center, 1161 21st Ave. S., Nashville, TN 37232, USA; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, 1161 21st Ave. S., Nashville, TN 37232, USA; Department of Electrical Engineering and Computer Science, Vanderbilt University, 400 24th Ave. S., Nashville, TN 37212, USA.
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Wang F, Lee SY, Adelnia F, Takahashi K, Harkins KD, He L, Zu Z, Ellinger P, Grundmann M, Harris RC, Takahashi T, Gore JC. Severity of polycystic kidney disease revealed by multiparametric MRI. Magn Reson Med 2023; 90:1151-1165. [PMID: 37093746 PMCID: PMC10805116 DOI: 10.1002/mrm.29679] [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: 12/22/2022] [Revised: 03/03/2023] [Accepted: 04/03/2023] [Indexed: 04/25/2023]
Abstract
PURPOSE We aimed to compare multiple MRI parameters, including relaxation rates (R 1 $$ {R}_1 $$ ,R 2 $$ {R}_2 $$ , andR 1 ρ $$ {R}_{1\rho } $$ ), ADC from diffusion weighted imaging, pool size ratio (PSR) from quantitative magnetization transfer, and measures of exchange from spin-lock imaging (S ρ $$ {S}_{\rho } $$ ), for assessing and predicting the severity of polycystic kidney disease (PKD) over time. METHODS Pcy/Pcy mice with CD1 strain, a mouse model of autosomal dominant PKD, were imaged at 5, 9, and 26 wk of age using a 7T MRI system. Twelve-week normal CD1 mice were used as controls. Post-mortem paraffin tissue sections were stained using hematoxylin and eosin and picrosirius red to identify histological changes. RESULTS Histology detected segmental cyst formation in the early stage (week 5) and progression of PKD over time in Pcy kidneys. InT 2 $$ {T}_2 $$ -weighted images, small cysts appeared locally in cystic kidneys in week 5 and gradually extended to the whole cortex and outer stripe of outer medulla region from week 5 to week 26. Regional PSR,R 1 $$ {R}_1 $$ ,R 2 $$ {R}_2 $$ , andR 1 ρ $$ {R}_{1\rho } $$ decreased consistently over time compared to normal kidneys, with significant changes detected in week 5. Among all the MRI measures,R 2 $$ {R}_2 $$ andR 1 ρ $$ {R}_{1\rho } $$ allow highest detectability to PKD, while PSR andR 1 $$ {R}_1 $$ have highest correlation with pathological indices of PKD. Using optimum MRI parameters as regressors, multiple linear regression provides reliable prediction of PKD progression. CONCLUSION R 2 $$ {R}_2 $$ ,R 1 $$ {R}_1 $$ , and PSR are sensitive indicators of the presence of PKD. Multiparametric MRI allows a comprehensive analysis of renal changes caused by cyst formation and expansion.
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Affiliation(s)
- Feng Wang
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center
- Vanderbilt O’Brien Kidney Research Center, Vanderbilt University Medical Center
| | - Seo Yeon Lee
- Division of Nephrology and Hypertension, Vanderbilt University Medical Center
| | - Fatemeh Adelnia
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center
| | - Keiko Takahashi
- Vanderbilt O’Brien Kidney Research Center, Vanderbilt University Medical Center
- Division of Nephrology and Hypertension, Vanderbilt University Medical Center
| | - Kevin D. Harkins
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37232
| | - Lilly He
- Division of Nephrology and Hypertension, Vanderbilt University Medical Center
| | - Zhongliang Zu
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center
| | - Philipp Ellinger
- Bayer AG Research & Development, Pharmaceuticals, 42113 Wuppertal, Germany
| | - Manuel Grundmann
- Bayer AG Research & Development, Pharmaceuticals, 42113 Wuppertal, Germany
| | - Raymond C. Harris
- Vanderbilt O’Brien Kidney Research Center, Vanderbilt University Medical Center
- Division of Nephrology and Hypertension, Vanderbilt University Medical Center
| | - Takamune Takahashi
- Vanderbilt O’Brien Kidney Research Center, Vanderbilt University Medical Center
- Division of Nephrology and Hypertension, Vanderbilt University Medical Center
| | - John C. Gore
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37232
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Hardy BM, Zhu Y, Harkins KD, Dhakal B, Martin JB, Xie J, Xu J, Does MD, Anderson AW, Gore JC. Experimental demonstration of diffusion limitations on resolution and SNR in MR microscopy. J Magn Reson 2023; 352:107479. [PMID: 37285709 PMCID: PMC10757347 DOI: 10.1016/j.jmr.2023.107479] [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] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 03/20/2023] [Accepted: 05/13/2023] [Indexed: 06/09/2023]
Abstract
PURPOSE MR microscopy is in principle capable of producing images at cellular resolution (<10 µm), but various factors limit the quality achieved in practice. A recognized limit on the signal to noise ratio and spatial resolution is the dephasing of transverse magnetization caused by diffusion of spins in strong gradients. Such effects may be reduced by using phase encoding instead of frequency encoding read-out gradients. However, experimental demonstration of the quantitative benefits of phase encoding are lacking, and the exact conditions in which it is preferred are not clearly established. We quantify the conditions where phase encoding outperforms a readout gradient with emphasis on the detrimental effects of diffusion on SNR and resolution. METHODS A 15.2 T Bruker MRI scanner, with 1 T/m gradients, and micro solenoid RF coils < 1 mm in diameter, were used to quantify diffusion effects on resolution and the signal to noise ratio of frequency and phase encoded acquisitions. Frequency and phase encoding's spatial resolution and SNR per square root time were calculated and measured for images at the diffusion limited resolution. The point spread function was calculated and measured for phase and frequency encoding using additional constant time phase gradients with voxels 3-15 µm in dimension. RESULTS The effect of diffusion during the readout gradient on SNR was experimentally demonstrated. The achieved resolutions of frequency and phase encoded acquisitions were measured via the point-spread-function and shown to be lower than the nominal resolution. SNR per square root time and actual resolution were calculated for a wide range of maximum gradient amplitudes, diffusion coefficients, and relaxation properties. The results provide a practical guide on how to choose between phase encoding and a conventional readout. Images of excised rat spinal cord at 10 µm × 10 µm in-plane resolution demonstrate phase encoding's benefits in the form of higher measured resolution and higher SNR than the same image acquired with a conventional readout. CONCLUSION We provide guidelines to determine the extent to which phase encoding outperforms frequency encoding in SNR and resolution given a wide range of voxel sizes, sample, and hardware properties.
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Affiliation(s)
- Benjamin M Hardy
- Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37232, USA; Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
| | - Yue Zhu
- MR Engineering, GE Healthcare, Waukesha, WI 53188, USA
| | - Kevin D Harkins
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37232, USA
| | - Bibek Dhakal
- Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37232, USA; Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Jonathan B Martin
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37232, USA
| | - Jingping Xie
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Junzhong Xu
- Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37232, USA; Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37232, USA
| | - Mark D Does
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37232, USA
| | - Adam W Anderson
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37232, USA
| | - John C Gore
- Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37232, USA; Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37232, USA
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Lee G, Does MD, Avila R, Kang J, Harkins KD, Wu Y, Banks WE, Park M, Lu D, Yan X, Kim JU, Won SM, Evans AG, Joseph JT, Kalmar CL, Pollins AC, Karagoz H, Thayer WP, Huang Y, Rogers JA. Implantable, Bioresorbable Radio Frequency Resonant Circuits for Magnetic Resonance Imaging. Adv Sci (Weinh) 2023:e2301232. [PMID: 37357139 DOI: 10.1002/advs.202301232] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 06/05/2023] [Indexed: 06/27/2023]
Abstract
Magnetic resonance imaging (MRI) is widely used in clinical care and medical research. The signal-to-noise ratio (SNR) in the measurement affects parameters that determine the diagnostic value of the image, such as the spatial resolution, contrast, and scan time. Surgically implanted radiofrequency coils can increase SNR of subsequent MRI studies of adjacent tissues. The resulting benefits in SNR are, however, balanced by significant risks associated with surgically removing these coils or with leaving them in place permanently. As an alternative, here the authors report classes of implantable inductor-capacitor circuits made entirely of bioresorbable organic and inorganic materials. Engineering choices for the designs of an inductor and a capacitor provide the ability to select the resonant frequency of the devices to meet MRI specifications (e.g., 200 MHz at 4.7 T MRI). Such devices enhance the SNR and improve the associated imaging capabilities. These simple, small bioelectronic systems function over clinically relevant time frames (up to 1 month) at physiological conditions and then disappear completely by natural mechanisms of bioresorption, thereby eliminating the need for surgical extraction. Imaging demonstrations in a nerve phantom and a human cadaver suggest that this technology has broad potential for post-surgical monitoring/evaluation of recovery processes.
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Affiliation(s)
- Geumbee Lee
- Querrey Simpson Institute for Bioelectronics, Northwestern University, Evanston, IL, 60208, USA
| | - Mark D Does
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, 37235, USA
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Raudel Avila
- Department of Mechanical Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Juyeon Kang
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Republic of Korea
| | - Kevin D Harkins
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Yunyun Wu
- Querrey Simpson Institute for Bioelectronics, Northwestern University, Evanston, IL, 60208, USA
| | - William E Banks
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, 37235, USA
| | - Minsu Park
- Querrey Simpson Institute for Bioelectronics, Northwestern University, Evanston, IL, 60208, USA
| | - Di Lu
- School of Microelectronics, University of Science and Technology of China, Hefei, Anhui, 230026, China
| | - Xinqiang Yan
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Jong Uk Kim
- Querrey Simpson Institute for Bioelectronics, Northwestern University, Evanston, IL, 60208, USA
| | - Sang Min Won
- Department of Electrical and Computer Engineering, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon-si, Gyeonggi-do, 16419, Republic of Korea
| | - Adam G Evans
- Department of Plastic Surgery, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Jeremy T Joseph
- Department of Plastic Surgery, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Christopher L Kalmar
- Department of Plastic Surgery, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Alonda C Pollins
- Department of Plastic Surgery, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Huseyin Karagoz
- Department of Plastic Surgery, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Wesley P Thayer
- Department of Plastic Surgery, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Yonggang Huang
- Department of Mechanical Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - John A Rogers
- Querrey Simpson Institute for Bioelectronics, Northwestern University, Evanston, IL, 60208, USA
- Department of Mechanical Engineering, Northwestern University, Evanston, IL, 60208, USA
- Department of Materials Science and Engineering, Department of Biomedical Engineering, Department of Neurological Surgery, Northwestern University, Evanston, IL, 60208, USA
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Ketsiri T, Uppuganti S, Harkins KD, Gochberg DF, Nyman JS, Does MD. T 1 relaxation of bound and pore water in cortical bone. NMR Biomed 2023; 36:e4878. [PMID: 36418236 DOI: 10.1002/nbm.4878] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 11/01/2022] [Accepted: 11/22/2022] [Indexed: 06/16/2023]
Abstract
MRI measures of bound and/or pore water concentration in cortical bone offer potential diagnostics of bone fracture risk. The transverse relaxation characteristics of both bound and pore water are relatively well understood and have been used to design clinical MRI pulse sequences to image each water pool quantitatively. However, these methods are also sensitive to longitudinal relaxation characteristics, which have been less well studied. Here, spectroscopic relaxometry measurements of 31 human cortical bone specimens provided a more detailed picture of T 1 of both bound and pore water. The results included mean, standard deviation, and range of T 1 spectra from both bound and pore water, as well as novel presentations of the 2D T 1 - T 2 distribution of pore water. Importantly, for each sample the pore water T 1 spectrum was found to span more than one order of magnitude and varied substantially across the 31 sample studies. Because many existing methods assume pore water T 1 to be mono-exponential and constant across individuals, the results were used to compute the potential effect neglecting this intra- and intersample T 1 variation on accurate MRI measurement of both bound and pore water concentrations. The greatest effect was found for adiabatic inversion recovery (AIR) based measurements of bound water concentration, which showed an average of 8.8% and as much as 37% error when using a common mono-exponential assumption of pore water T 1 . Despite these errors, the simulated AIR measurements were still moderately well correlated with the bound water concentrations derived from the spectroscopic data.
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Affiliation(s)
- Thammathida Ketsiri
- Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Sasidhar Uppuganti
- Orthopaedic Surgery, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Veterans Affairs, Tennessee Valley Healthcare System, Nashville, Tennessee, USA
- Center for Bone Biology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Kevin D Harkins
- Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Radiology & Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Daniel F Gochberg
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Radiology & Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Physics and Astronomy, Vanderbilt University, Nashville, Tennessee, USA
| | - Jeffry S Nyman
- Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Orthopaedic Surgery, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Veterans Affairs, Tennessee Valley Healthcare System, Nashville, Tennessee, USA
- Radiology & Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Mark D Does
- Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Radiology & Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Electrical Engineering, Vanderbilt University, Nashville, Tennessee, USA
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Adelnia F, Davis LT, Acosta LM, Puckett A, Wang F, Zu Z, Harkins KD, Gore JC. R 1ρ dispersion in white matter correlates with quantitative metrics of cognitive impairment. Neuroimage Clin 2023; 37:103366. [PMID: 36889101 PMCID: PMC10009712 DOI: 10.1016/j.nicl.2023.103366] [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: 12/27/2022] [Revised: 02/21/2023] [Accepted: 02/27/2023] [Indexed: 03/06/2023]
Abstract
Much previous neuroimaging research in Alzheimer's disease has focused on the roles of amyloid and tau proteins, but recent studies have implicated microvascular changes in white matter as early indicators of damage related to later dementia. We used MRI to derive novel, non-invasive measurements of R1ρ dispersion using different locking fields to characterize variations of microvascular structure and integrity in brain tissues. We developed a non-invasive 3D R1ρ dispersion imaging technique using different locking fields at 3T. We acquired MR images and cognitive assessments of participants with mild cognitive impairment (MCI) and compared them to age-matched healthy controls in a cross-sectional study. After providing informed consent, 40 adults aged 62 to 82 years (n = 17 MCI) were included in this study. White matter ΔR1ρ-fraction measured by R1ρ dispersion imaging showed a strong correlation with the cognitive status of older adults (βstd = -0.4, p-value < 0.01) independent of age, in contrast to other conventional MRI markers such as T2, R1ρ, and white matter hyperintense lesion volume (WMHs) measured with T2-FLAIR. The correlation of WMHs with cognitive status was no longer significant after adjusting for age and sex in linear regression analysis, and the size of the regression coefficient was substantially decreased (53% lower). This work establishes a new non-invasive method that potentially characterizes impairment of the microvascular structure of white matter in MCI patients compared to healthy controls. The application of this method in longitudinal studies would improve our fundamental understanding of the pathophysiologic changes that accompany abnormal cognitive decline with aging and help identify potential targets for treatment of Alzheimer's disease.
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Affiliation(s)
- Fatemeh Adelnia
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA.
| | - Larry T Davis
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Lealani Mae Acosta
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Amanda Puckett
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Feng Wang
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Zhongliang Zu
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Kevin D Harkins
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
| | - John C Gore
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
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Harkins KD, Ketsiri T, Nyman JS, Does MD. Fast bound and pore water mapping of cortical bone with arbitrary slice oriented two-dimensional ultra-short echo time. Magn Reson Med 2023; 89:767-773. [PMID: 36226656 PMCID: PMC9897494 DOI: 10.1002/mrm.29484] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [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: 07/01/2022] [Revised: 09/07/2022] [Accepted: 09/20/2022] [Indexed: 02/05/2023]
Abstract
PURPOSE Extend fast, two-dimensional (2D) methods of bound and pore water mapping in bone to arbitrary slice orientation. METHODS To correct for slice profile artifacts caused by gradient errors of half pulse 2D ultra-short echo time (UTE), we developed a library of predistorted gradient waveforms that can be used to interpolate optimized gradient waveforms for 2D UTE slice selection. We also developed a method to estimate and correct for a bulk phase difference between the two half pulse excitations used for 2D UTE signal excitation. Bound water images were acquired in three healthy subjects with adiabatic inversion recovery prepared 2D UTE, while pore water images were acquired after short-T2 signals were suppressed with double adiabatic inversion recovery preparation. The repeatability of bound and pore water imaging with 2D UTE was tested by repeating acquisitions after repositioning. RESULTS The library-based interpolation of optimized slice select gradient waveforms combined with the method to estimate bulk phase between two excitations provided compact slice profiles for half pulse excited 2D UTE. Quantitative bound and pore water values were highly repeatable-the pooled SD of bound water across all three subjects was 0.38 mol1 $$ {}^1 $$ H/L, while pooled SD of pore water was 0.30 mol1 $$ {}^1 $$ H/L. CONCLUSION Fast, quantitative, 2D UTE-based bound and pore water images can be acquired at arbitrary oblique orientations after correcting for errors in the slice select gradient waveform and bulk phase shift between the two half acquisitions.
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Affiliation(s)
- Kevin D Harkins
- Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Institute of Image Science, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA
| | - Thammathida Ketsiri
- Institute of Image Science, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA
| | - Jeffry S Nyman
- Institute of Image Science, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA
- Department of Veterans Affairs, Tennessee Valley Healthcare System, Nashville, Tennessee, USA
- Orthopaedic Surgery and Rehabilitation, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Center for Bone Biology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Mark D Does
- Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Institute of Image Science, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA
- Electrical Engineering, Vanderbilt University Medical Center, Nashville, Tennessee, USA
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8
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Xie D, Murray J, Lartey R, Gaj S, Kim J, Li M, Eck BL, Winalski CS, Altahawi F, Jones MH, Obuchowski NA, Huston LJ, Harkins KD, Friel HT, Damon BM, Knopp MV, Kaeding CC, Spindler KP, Li X. Multi-vendor multi-site quantitative MRI analysis of cartilage degeneration 10 Years after anterior cruciate ligament reconstruction: MOON-MRI protocol and preliminary results. Osteoarthritis Cartilage 2022; 30:1647-1657. [PMID: 36049665 PMCID: PMC9671830 DOI: 10.1016/j.joca.2022.08.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [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: 01/08/2022] [Revised: 07/12/2022] [Accepted: 08/01/2022] [Indexed: 02/02/2023]
Abstract
OBJECTIVE To describe the protocol of a multi-vendor, multi-site quantitative MRI study for knee post-traumatic osteoarthritis (PTOA), and to present preliminary results of cartilage degeneration using MR T1ρ and T2 imaging 10 years after anterior cruciate ligament reconstruction (ACLR). DESIGN This study involves three sites and two MR platforms. The patients are from a nested cohort (termed as Onsite cohort) within the Multicenter Orthopaedic Outcomes Network (MOON) cohort 10 years after ACLR. Phantoms and controls were scanned for evaluating reproducibility. Cartilage was automatically segmented, and T1ρ and T2 were compared between operated, contralateral, and control knees. RESULTS Sixty-eight ACL-reconstructed patients and 20 healthy controls were included. In phantoms, the intra-site coefficients of variation (CVs) of repeated scans ranged 1.8-2.1% for T1ρ and 1.3-1.7% for T2. The inter-site CVs ranged 1.6-2.1% for T1ρ and 1.1-1.4% for T2. In human subjects, the intra-site scan/rescan CVs ranged 2.2-3.5% for T1ρ and 2.6-4.9% for T2 for the six major compartments. In patients, operated knees showed significantly higher T1ρ and T2 values mainly in medial femoral condyle, medial tibia and trochlear cartilage compared with contralateral knees, and showed significantly higer T1ρ and T2 values in all six compartments compared to healthy control knees. The patient contralateral knees showed higher T1ρ and T2 values mainly in the lateral femoral condyle, lateral tibia, trochlear, and patellar cartilage compared to healthy control knees. CONCLUSION A platform and workflow with rigorous quality control has been established for a multi-vendor multi-site quantitative MRI study in evaluating PTOA 10 years after ACLR. Our preliminary report suggests significant cartilage matrix changes in both operated and contralateral knees compared with healthy control knees.
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Affiliation(s)
- D Xie
- Program of Advanced Musculoskeletal Imaging (PAMI), Cleveland Clinic, Cleveland, OH, USA; Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA; Department of Orthopaedics, Xiangya Hospital, Central South University, Changsha, Hunan, China.
| | - J Murray
- Program of Advanced Musculoskeletal Imaging (PAMI), Cleveland Clinic, Cleveland, OH, USA; Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA.
| | - R Lartey
- Program of Advanced Musculoskeletal Imaging (PAMI), Cleveland Clinic, Cleveland, OH, USA; Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA.
| | - S Gaj
- Program of Advanced Musculoskeletal Imaging (PAMI), Cleveland Clinic, Cleveland, OH, USA; Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA.
| | - J Kim
- Program of Advanced Musculoskeletal Imaging (PAMI), Cleveland Clinic, Cleveland, OH, USA; Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA.
| | - M Li
- Program of Advanced Musculoskeletal Imaging (PAMI), Cleveland Clinic, Cleveland, OH, USA; Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA.
| | - B L Eck
- Program of Advanced Musculoskeletal Imaging (PAMI), Cleveland Clinic, Cleveland, OH, USA; Department of Diagnostic Radiology, Imaging Institute, Cleveland Clinic, Cleveland, OH, USA.
| | - C S Winalski
- Program of Advanced Musculoskeletal Imaging (PAMI), Cleveland Clinic, Cleveland, OH, USA; Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA; Department of Diagnostic Radiology, Imaging Institute, Cleveland Clinic, Cleveland, OH, USA.
| | - F Altahawi
- Program of Advanced Musculoskeletal Imaging (PAMI), Cleveland Clinic, Cleveland, OH, USA; Department of Diagnostic Radiology, Imaging Institute, Cleveland Clinic, Cleveland, OH, USA.
| | - M H Jones
- Department of Orthopaedic Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
| | - N A Obuchowski
- Program of Advanced Musculoskeletal Imaging (PAMI), Cleveland Clinic, Cleveland, OH, USA; Department of Quantitative Health Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA.
| | - L J Huston
- Department of Orthopaedics and Rehabilitation, Vanderbilt University Medical Center, Nashville, TN, USA.
| | - K D Harkins
- Departments of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA.
| | - H T Friel
- MR Clinical Science, Philips Healthcare, Highland Heights, OH, USA.
| | - B M Damon
- Departments of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA.
| | - M V Knopp
- Wright Center of Innovation in Biomedical Imaging, Department of Radiology, The Ohio State University, Columbus, OH, USA.
| | - C C Kaeding
- Department of Orthopaedic Surgery, The Ohio State University, Columbus, OH, USA.
| | - K P Spindler
- Program of Advanced Musculoskeletal Imaging (PAMI), Cleveland Clinic, Cleveland, OH, USA; Department of Orthopaedic Surgery, Cleveland Clinic, Cleveland, OH, USA.
| | - X Li
- Program of Advanced Musculoskeletal Imaging (PAMI), Cleveland Clinic, Cleveland, OH, USA; Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA; Department of Diagnostic Radiology, Imaging Institute, Cleveland Clinic, Cleveland, OH, USA.
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9
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Wang F, Otsuka T, Adelnia F, Takahashi K, Delgado R, Harkins KD, Zu Z, de Caestecker MP, Harris RC, Gore JC, Takahashi T. Multiparametric magnetic resonance imaging in diagnosis of long-term renal atrophy and fibrosis after ischemia reperfusion induced acute kidney injury in mice. NMR Biomed 2022; 35:e4786. [PMID: 35704387 PMCID: PMC10805124 DOI: 10.1002/nbm.4786] [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] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 05/31/2022] [Accepted: 06/14/2022] [Indexed: 06/15/2023]
Abstract
Tubular atrophy and fibrosis are pathological changes that determine the prognosis of kidney disease induced by acute kidney injury (AKI). We aimed to evaluate multiple magnetic resonance imaging (MRI) parameters, including pool size ratio (PSR) from quantitative magnetization transfer, relaxation rates, and measures from spin-lock imaging ( R 1 ρ and S ρ ), for assessing the pathological changes associated with AKI-induced kidney disease. Eight-week-old male C57BL/6 J mice first underwent unilateral ischemia reperfusion injury (IRI) induced by reperfusion after 45 min of ischemia. They were imaged using a 7T MRI system 56 days after the injury. Paraffin tissue sections were stained using Masson trichrome and picrosirius red to identify histopathological changes such as tubular atrophy and fibrosis. Histology detected extensive tubular atrophy and moderate fibrosis in the cortex and outer stripe of the outer medulla (CR + OSOM) and more prominent fibrosis in the inner stripe of the outer medulla (ISOM) of IRI kidneys. In the CR + OSOM region, evident decreases in PSR, R 1 , R 2 , R 1 ρ , and S ρ showed in IRI compared with contralateral kidneys, with PSR and S ρ exhibiting the most significant changes. In addition, the exchange parameter S ρ dropped by the largest degree among all the MRI parameters, whileR 2 * increased significantly. In the ISOM of IRI kidneys, PSR increased while S ρ kept decreasing. R 2 , R 1 ρ , andR 2 * all increased due to more severe fibrosis in this region. Among MRI measures, PSR and R 1 ρ showed the highest detectability of renal changes no matter whether tubular atrophy or fibrosis dominated.R 2 * and S ρ could be more specific to a single pathological event than other MRI measures because onlyR 2 * increased and S ρ decreased consistently when either fibrosis or tubular atrophy dominated, and their correlations with fibrosis scores were higher than other MRI measures. Multiparametric MRI may enable a more comprehensive analysis of histopathological changes following AKI.
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Affiliation(s)
- Feng Wang
- Vanderbilt University Institute of Imaging Science,
Vanderbilt University Medical Center, Nashville, TN 37232
- Department of Radiology and Radiological Sciences,
Vanderbilt University Medical Center, Nashville, TN 37232
- Vanderbilt O’Brien Kidney Research Center,
Vanderbilt University Medical Center, Nashville, TN 37232
| | - Tadashi Otsuka
- Division of Nephrology and Hypertension, Vanderbilt
University Medical Center, Nashville, TN 37232
| | - Fatemeh Adelnia
- Vanderbilt University Institute of Imaging Science,
Vanderbilt University Medical Center, Nashville, TN 37232
| | - Keiko Takahashi
- Division of Nephrology and Hypertension, Vanderbilt
University Medical Center, Nashville, TN 37232
- Vanderbilt O’Brien Kidney Research Center,
Vanderbilt University Medical Center, Nashville, TN 37232
| | - Rachel Delgado
- Division of Nephrology and Hypertension, Vanderbilt
University Medical Center, Nashville, TN 37232
- Vanderbilt O’Brien Kidney Research Center,
Vanderbilt University Medical Center, Nashville, TN 37232
| | - Kevin D. Harkins
- Vanderbilt University Institute of Imaging Science,
Vanderbilt University Medical Center, Nashville, TN 37232
- Department of Radiology and Radiological Sciences,
Vanderbilt University Medical Center, Nashville, TN 37232
- Department of Biomedical Engineering, Vanderbilt
University, Nashville, TN 37232
| | - Zhongliang Zu
- Vanderbilt University Institute of Imaging Science,
Vanderbilt University Medical Center, Nashville, TN 37232
- Department of Radiology and Radiological Sciences,
Vanderbilt University Medical Center, Nashville, TN 37232
| | - Mark P. de Caestecker
- Division of Nephrology and Hypertension, Vanderbilt
University Medical Center, Nashville, TN 37232
- Vanderbilt O’Brien Kidney Research Center,
Vanderbilt University Medical Center, Nashville, TN 37232
| | - Raymond C. Harris
- Division of Nephrology and Hypertension, Vanderbilt
University Medical Center, Nashville, TN 37232
- Vanderbilt O’Brien Kidney Research Center,
Vanderbilt University Medical Center, Nashville, TN 37232
| | - John C. Gore
- Vanderbilt University Institute of Imaging Science,
Vanderbilt University Medical Center, Nashville, TN 37232
- Department of Radiology and Radiological Sciences,
Vanderbilt University Medical Center, Nashville, TN 37232
- Department of Biomedical Engineering, Vanderbilt
University, Nashville, TN 37232
| | - Takamune Takahashi
- Division of Nephrology and Hypertension, Vanderbilt
University Medical Center, Nashville, TN 37232
- Vanderbilt O’Brien Kidney Research Center,
Vanderbilt University Medical Center, Nashville, TN 37232
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10
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Ketsiri T, Uppuganti S, Harkins KD, Gochberg DF, Nyman JS, Does MD. Finite element analysis of bone mechanical properties using MRI-derived bound and pore water concentration maps. Comput Methods Biomech Biomed Engin 2022; 26:905-916. [PMID: 35822868 PMCID: PMC9837311 DOI: 10.1080/10255842.2022.2098016] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Ultrashort echo time (UTE) MRI techniques can be used to image the concentration of water in bones. Particularly, quantitative MRI imaging of collagen-bound water concentration (Cbw) and pore water concentration (Cpw) in cortical bone have been shown as potential biomarkers for bone fracture risk. To investigate the effect of Cbw and Cpw on the evaluation of bone mechanical properties, MRI-based finite element models of cadaver radii were generated with tissue material properties derived from 3 D maps of Cbw and Cpw measurements. Three-point bending tests were simulated by means of the finite element method to predict bending properties of the bone and the results were compared with those from direct mechanical testing. The study results demonstrate that these MRI-derived measures of Cbw and Cpw improve the prediction of bone mechanical properties in cadaver radii and have the potential to be useful in assessing patient-specific bone fragility risk.
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Affiliation(s)
- Thammathida Ketsiri
- Biomedical Engineering, Vanderbilt University, Nashville, TN, United States,Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, TN, United States
| | - Sasidhar Uppuganti
- Department of Orthopaedic Surgery & Rehabilitation, Vanderbilt University, Nashville, TN, United States,Tennessee Valley Healthcare System, Department of Veterans Affairs, Nashville, TN, United States,Center for Bone Biology, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Kevin D. Harkins
- Biomedical Engineering, Vanderbilt University, Nashville, TN, United States,Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, TN, United States,Radiology & Radiological Sciences, Vanderbilt University, Nashville, TN, United States
| | - Daniel F. Gochberg
- Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, TN, United States,Radiology & Radiological Sciences, Vanderbilt University, Nashville, TN, United States,Department of Physics and Astronomy, Vanderbilt University, Nashville, TN, United States
| | - Jeffry S. Nyman
- Biomedical Engineering, Vanderbilt University, Nashville, TN, United States,Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, TN, United States,Department of Orthopaedic Surgery & Rehabilitation, Vanderbilt University, Nashville, TN, United States,Tennessee Valley Healthcare System, Department of Veterans Affairs, Nashville, TN, United States,Center for Bone Biology, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Mark D. Does
- Biomedical Engineering, Vanderbilt University, Nashville, TN, United States,Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, TN, United States,Radiology & Radiological Sciences, Vanderbilt University, Nashville, TN, United States,Electrical Engineering, Vanderbilt University, Nashville, TN, United States
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11
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Harkins KD, Does MD. Efficient gradient waveform measurements with variable-prephasing. J Magn Reson 2021; 327:106945. [PMID: 33784601 PMCID: PMC8141008 DOI: 10.1016/j.jmr.2021.106945] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 01/21/2021] [Accepted: 02/15/2021] [Indexed: 06/12/2023]
Abstract
Accurate measurement of gradient waveform errors can often improve image quality in sequences with time varying readout and excitation waveforms. Self-encoding or offset-slice sequences are commonly used to measure gradient waveforms. However, the self-encoding method requires a long scan time, while the offset-slice method is often low precision, requiring the thickness of the excited slice to be small compared to the maximal k-space encoded by the test waveform. This work introduces a hybrid these methods, called variable-prephasing. Using a straightforward algebraic model, we demonstrate that variable-prephasing improves the precision of the waveform measurement by allowing acquisition of larger slice thicknesses. Experiments in a phantom were used to validate the theoretical predictions, showing that the precision of variable-prephasing gradient waveform measurements improves with increasing slice thickness.
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Affiliation(s)
- Kevin D Harkins
- Biomedical Engineering, Vanderbilt University, United States; Institute of Imaging Science, Vanderbilt University, United States.
| | - Mark D Does
- Biomedical Engineering, Vanderbilt University, United States; Institute of Imaging Science, Vanderbilt University, United States
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12
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Harkins KD, Beaulieu C, Xu J, Gore JC, Does MD. A simple estimate of axon size with diffusion MRI. Neuroimage 2020; 227:117619. [PMID: 33301942 PMCID: PMC7949481 DOI: 10.1016/j.neuroimage.2020.117619] [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: 05/22/2020] [Revised: 11/06/2020] [Accepted: 11/29/2020] [Indexed: 12/18/2022] Open
Abstract
Noninvasive estimation of mean axon diameter presents a new opportunity to explore white matter plasticity, development, and pathology. Several diffusion-weighted MRI (DW-MRI) methods have been proposed to measure the average axon diameter in white matter, but they typically require many diffusion encoding measurements and complicated mathematical models to fit the signal to multiple tissue compartments, including intra- and extra-axonal spaces. Here, Monte Carlo simulations uncovered a straightforward DW-MRI metric of axon diameter: the change in radial apparent diffusion coefficient estimated at different effective diffusion times, ΔD⊥. Simulations indicated that this metric increases monotonically within a relevant range of effective mean axon diameter while being insensitive to changes in extra-axonal volume fraction, axon diameter distribution, g-ratio, and influence of myelin water. Also, a monotonic relationship was found to exist for signals coming from both intra- and extra-axonal compartments. The slope in ΔD⊥ with effective axon diameter increased with the difference in diffusion time of both oscillating and pulsed gradient diffusion sequences.
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Affiliation(s)
- Kevin D Harkins
- Biomedical Engineering, Vanderbilt University, United States; Institute of Imaging Science, Vanderbilt University, United States.
| | | | - Junzhong Xu
- Institute of Imaging Science, Vanderbilt University, United States; Radiology and Radiological Sciences, Vanderbilt University Medical Center, United States
| | - John C Gore
- Biomedical Engineering, Vanderbilt University, United States; Institute of Imaging Science, Vanderbilt University, United States; Radiology and Radiological Sciences, Vanderbilt University Medical Center, United States
| | - Mark D Does
- Biomedical Engineering, Vanderbilt University, United States; Institute of Imaging Science, Vanderbilt University, United States
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13
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Petersen KJ, Garza M, Donahue PM, Harkins KD, Marton A, Titze J, Donahue MJ, Crescenzi R. Neuroimaging of Cerebral Blood Flow and Sodium in Women with Lipedema. Obesity (Silver Spring) 2020; 28:1292-1300. [PMID: 32568462 PMCID: PMC7360333 DOI: 10.1002/oby.22837] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [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] [Received: 01/30/2020] [Revised: 03/16/2020] [Accepted: 04/09/2020] [Indexed: 12/25/2022]
Abstract
OBJECTIVE Lipedema is characterized by pain, fatigue, and excessive adipose tissue and sodium accumulation of the lower extremities. This case-control study aims to determine whether sodium or vascular dysfunction is present in the central nervous system. METHODS Brain magnetic resonance imaging was performed at 3 T in patients with lipedema (n = 15) and control (n = 18) participants matched for sex, age, race, and BMI. Standard anatomical imaging and intracranial angiography were applied to evaluate brain volume and vasculopathy, respectively; arterial spin labeling and sodium magnetic resonance imaging were applied to quantify cerebral blood flow (CBF) (milliliters per 100 grams of tissue/minute) and brain tissue sodium content (millimoles per liter), respectively. A Mann-Whitney U test (significance criteria P < 0.05) was applied to evaluate group differences. RESULTS No differences in tissue volume, white matter hyperintensities, intracranial vasculopathy, or tissue sodium content were observed between groups. Gray matter CBF was elevated (P = 0.03) in patients with lipedema (57.2 ± 9.6 mL per 100 g/min) versus control participants (49.8 ± 9.1 mL per 100 g/min). CONCLUSIONS Findings provide evidence that brain sodium and tissue fractions are similar between patients with lipedema and control participants and that patients with lipedema do not exhibit abnormal radiological indicators of intracranial vasculopathy or ischemic injury. Potential explanations for elevated CBF are discussed in the context of the growing literature on lipedema symptomatology and vascular dysfunction.
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Affiliation(s)
- Kalen J. Petersen
- Radiology and Radiological Sciences, Vanderbilt University School of Medicine, Nashville TN, USA
- Corresponding author: Kalen J. Petersen, PhD, Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, 1161 21 Avenue South, Medical Center North AA-1105B, Nashville, TN 37232, USA, Tel: +1 615.343.7182, Fax: +1 615.322.0734,
| | - Maria Garza
- Radiology and Radiological Sciences, Vanderbilt University School of Medicine, Nashville TN, USA
| | - Paula M.C. Donahue
- Physical Medicine and Rehabilitation, Vanderbilt University School of Medicine, Nashville TN, USA
- Dayani Center for Health and Wellness, Vanderbilt University School of Medicine, Nashville TN, USA
| | - Kevin D. Harkins
- Biomedical Engineering, Vanderbilt University, Nashville TN, USA
| | - Adriana Marton
- Cardiovascular and Metabolic Disease, Duke-National University of Singapore Medical School
| | - Jens Titze
- Cardiovascular and Metabolic Disease, Duke-National University of Singapore Medical School
| | - Manus J. Donahue
- Radiology and Radiological Sciences, Vanderbilt University School of Medicine, Nashville TN, USA
- Neurology, Vanderbilt University School of Medicine, Nashville, TN, USA
- Psychiatry and Behavioral Sciences, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Rachelle Crescenzi
- Radiology and Radiological Sciences, Vanderbilt University School of Medicine, Nashville TN, USA
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14
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Tétreault P, Harkins KD, Baron CA, Stobbe R, Does MD, Beaulieu C. Diffusion time dependency along the human corpus callosum and exploration of age and sex differences as assessed by oscillating gradient spin-echo diffusion tensor imaging. Neuroimage 2020; 210:116533. [PMID: 31935520 DOI: 10.1016/j.neuroimage.2020.116533] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [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: 10/04/2019] [Revised: 01/06/2020] [Accepted: 01/09/2020] [Indexed: 12/19/2022] Open
Abstract
Conventional diffusion imaging uses pulsed gradient spin echo (PGSE) waveforms with diffusion times of tens of milliseconds (ms) to infer differences of white matter microstructure. The combined use of these long diffusion times with short diffusion times (<10 ms) enabled by oscillating gradient spin echo (OGSE) waveforms can enable more sensitivity to changes of restrictive boundaries on the scale of white matter microstructure (e.g. membranes reflecting the axon diameters). Here, PGSE and OGSE images were acquired at 4.7 T from 20 healthy volunteers aged 20-73 years (10 males). Mean, radial, and axial diffusivity, as well as fractional anisotropy were calculated in the genu, body and splenium of the corpus callosum (CC). Monte Carlo simulations were also conducted to examine the relationship of intra- and extra-axonal radial diffusivity with diffusion time over a range of axon diameters and distributions. The results showed elevated diffusivities with OGSE relative to PGSE in the genu and splenium (but not the body) in both males and females, but the OGSE-PGSE difference was greater in the genu for males. Females showed positive correlations of OGSE-PGSE diffusivity difference with age across the CC, whereas there were no such age correlations in males. Simulations of radial diffusion demonstrated that for axon sizes in human brain both OGSE and PGSE diffusivities were dominated by extra-axonal water, but the OGSE-PGSE difference nonetheless increased with area-weighted outer-axon diameter. Therefore, the lack of OGSE-PGSE difference in the body is not entirely consistent with literature that suggests it is composed predominantly of axons with large diameter. The greater OGSE-PGSE difference in the genu of males could reflect larger axon diameters than females. The OGSE-PGSE difference correlation with age in females could reflect loss of smaller axons at older ages. The use of OGSE with short diffusion times to sample the microstructural scale of restriction implies regional differences of axon diameters along the corpus callosum with preliminary results suggesting a dependence on age and sex.
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Affiliation(s)
- Pascal Tétreault
- Department of Biomedical Engineering, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Kevin D Harkins
- Institute of Imaging Science and Department of Biomedical Engineering, Vanderbilt, University, Nashville, TN, USA
| | - Corey A Baron
- Department of Medical Biophysics, Western University, London, ON, Canada
| | - Rob Stobbe
- Department of Biomedical Engineering, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Mark D Does
- Institute of Imaging Science and Department of Biomedical Engineering, Vanderbilt, University, Nashville, TN, USA
| | - Christian Beaulieu
- Department of Biomedical Engineering, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada.
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15
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Does MD, Olesen JL, Harkins KD, Serradas-Duarte T, Gochberg DF, Jespersen SN, Shemesh N. Evaluation of principal component analysis image denoising on multi-exponential MRI relaxometry. Magn Reson Med 2019; 81:3503-3514. [PMID: 30720206 PMCID: PMC6955240 DOI: 10.1002/mrm.27658] [Citation(s) in RCA: 25] [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] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 11/26/2018] [Accepted: 12/18/2018] [Indexed: 12/11/2022]
Abstract
PURPOSE Multi-exponential relaxometry is a powerful tool for characterizing tissue, but generally requires high image signal-to-noise ratio (SNR). This work evaluates the use of principal-component-analysis (PCA) denoising to mitigate these SNR demands and improve the precision of relaxometry measures. METHODS PCA denoising was evaluated using both simulated and experimental MRI data. Bi-exponential transverse relaxation signals were simulated for a wide range of acquisition and sample parameters, and experimental data were acquired from three excised and fixed mouse brains. In both cases, standard relaxometry analysis was performed on both original and denoised image data, and resulting estimated signal parameters were compared. RESULTS Denoising reduced the root-mean-square-error of parameters estimated from multi-exponential relaxometry by factors of ≈3×, for typical acquisition and sample parameters. Denoised images and subsequent parameter maps showed little or no signs of spatial artifact or loss of resolution. CONCLUSION Experimental studies and simulations demonstrate that PCA denoising of MRI relaxometry data is an effective method of improving parameter precision without sacrificing image resolution. This simple yet important processing step thus paves the way for broader applicability of multi-exponential MRI relaxometry.
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Affiliation(s)
- Mark D. Does
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, US
- Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, US
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, US
- Department of Electrical Engineering, Vanderbilt University, Nashville, TN, USA
| | - Jonas Lynge Olesen
- Center of Functionally Integrative Neuroscience, Aarhus University Hospital, Aarhus, Denmark
- Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark
| | - Kevin D. Harkins
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, US
- Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, US
| | | | - Daniel F. Gochberg
- Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, US
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, US
| | - Sune N. Jespersen
- Center of Functionally Integrative Neuroscience, Aarhus University Hospital, Aarhus, Denmark
- Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark
| | - Noam Shemesh
- Champalimaud Centre for the Unknown, Lisbon, Portugal
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16
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Manhard MK, Harkins KD, Gochberg DF, Nyman JS, Does MD. 30-Second bound and pore water concentration mapping of cortical bone using 2D UTE with optimized half-pulses. Magn Reson Med 2017; 77:945-950. [PMID: 28090655 DOI: 10.1002/mrm.26605] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2017] [Revised: 11/18/2016] [Accepted: 12/21/2016] [Indexed: 11/09/2022]
Abstract
PURPOSE MRI of cortical bone has the potential to offer new information about fracture risk. Current methods are typically performed with 3D acquisitions, which suffer from long scan times and are generally limited to extremities. This work proposes using 2D UTE with half pulses for quantitatively mapping bound and pore water in cortical bone. METHODS Half-pulse 2D UTE methods were implemented on a 3T Philips Achieva scanner using an optimized slice-select gradient waveform, with preparation pulses to selectively image bound or pore water. The 2D methods were quantitatively compared with previously implemented 3D methods in the tibia in five volunteers. RESULTS The mean difference between bound and pore water concentration acquired from 3D and 2D sequences was 0.6 and 0.9 mol 1 H/Lbone (3 and 12%, respectively). While 2D pore water methods tended to slightly overestimate concentrations relative to 3D methods, differences were less than scan-rescan uncertainty and expected differences between healthy and fracture-prone bones. CONCLUSION Quantitative bound and pore water concentration mapping in cortical bone can be accelerated by 2 orders of magnitude using 2D protocols with optimized half-pulse excitation. Magn Reson Med 77:945-950, 2017. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Mary Kate Manhard
- Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA.,Vanderbilt University Institute of Imaging Science, Nashville, Tennessee, USA
| | - Kevin D Harkins
- Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA.,Vanderbilt University Institute of Imaging Science, Nashville, Tennessee, USA
| | - Daniel F Gochberg
- Vanderbilt University Institute of Imaging Science, Nashville, Tennessee, USA.,Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA.,Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee, USA
| | - Jeffry S Nyman
- Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA.,Vanderbilt University Institute of Imaging Science, Nashville, Tennessee, USA.,Department of Veterans Affairs, Tennessee Valley Healthcare System, Nashville, Tennessee, USA.,Orthopaedic Surgery and Rehabilitation, Vanderbilt University, Nashville, Tennessee, USA.,Center for Bone Biology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Mark D Does
- Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA.,Vanderbilt University Institute of Imaging Science, Nashville, Tennessee, USA.,Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA.,Electrical Engineering, Vanderbilt University, Nashville, Tennessee, USA
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17
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Abstract
While myelinated axons present an important barrier to water diffusion, many models used to interpret DWI signal neglect other potential influences of myelin. In this work, Monte Carlo simulations were used to test the sensitivity of DWI results to the diffusive properties of water within myelin. Within these simulations, the apparent diffusion coefficient (D app) varied slowly over several orders of magnitude of the coefficient of myelin water diffusion (D m), but exhibited important differences compared to D app values simulated that neglect D m (=0). Compared to D app, the apparent diffusion kurtosis (K app) was generally more sensitive to D m. Simulations also tested the sensitivity of D app and K app to the amount of myelin present. Unique variations in D app and K app caused by differences in the myelin volume fraction were diminished when myelin water diffusion was included. Also, expected trends in D app and K app with experimental echo time were reduced or inverted when accounting for myelin water diffusion, and these reduced/inverted trends were seen experimentally in ex vivo rat brain DWI experiments. In general, myelin water has the potential to subtly influence DWI results and bias models of DWI that neglect these components of white matter.
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Affiliation(s)
- K D Harkins
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA. Institute of Imaging Science, Vanderbilt University, Nashville, TN, USA
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18
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Xu J, Li H, Li K, Harkins KD, Jiang X, Xie J, Kang H, Dortch RD, Anderson AW, Does MD, Gore JC. Fast and simplified mapping of mean axon diameter using temporal diffusion spectroscopy. NMR Biomed 2016; 29:400-410. [PMID: 27077155 PMCID: PMC4832578 DOI: 10.1002/nbm.3484] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Mapping axon diameter is of interest for the potential diagnosis and monitoring of various neuronal pathologies. Advanced diffusion-weighted MRI methods have been developed to measure mean axon diameters non-invasively, but suffer major drawbacks that prevent their direct translation into clinical practice, such as complex non-linear data fitting and, more importantly, long scanning times that are usually not tolerable for most human subjects. In the current study, temporal diffusion spectroscopy using oscillating diffusion gradients was used to measure mean axon diameters with high sensitivity to small axons in the central nervous system. Axon diameters have been found to be correlated with a novel metric, DDR⊥ (the rate of dispersion of the perpendicular diffusion coefficient with gradient frequency), which is a model-free quantity that does not require complex data analyses and can be obtained from two diffusion coefficient measurements in clinically relevant times with conventional MRI machines. A comprehensive investigation including computer simulations and animal experiments ex vivo showed that measurements of DDR⊥ agree closely with histological data. In humans in vivo, DDR⊥ was also found to correlate well with reported mean axon diameters in human corpus callosum, and the total scan time was only about 8 min. In conclusion, DDR⊥ may have potential to serve as a fast, simple and model-free approach to map the mean axon diameter of white matter in clinics for assessing axon diameter changes.
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Affiliation(s)
- Junzhong Xu
- Institute of Imaging Science, Vanderbilt University, Nashville, TN, USA; Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, USA; Department of Physics and Astronomy, Vanderbilt University, Nashville, TN, USA.
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19
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Harkins KD, Xu J, Dula AN, Li K, Valentine WM, Gochberg DF, Gore JC, Does MD. The microstructural correlates of T1 in white matter. Magn Reson Med 2015; 75:1341-5. [PMID: 25920491 DOI: 10.1002/mrm.25709] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [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: 01/08/2015] [Revised: 02/11/2015] [Accepted: 03/05/2015] [Indexed: 12/14/2022]
Abstract
PURPOSE Several studies have shown strong correlations between myelin content and T1 within the brain, and have even suggested that T1 can be used to estimate myelin content. However, other micro-anatomical features such as compartment size are known to affect longitudinal relaxation rates, similar to compartment size effects in porous media. METHODS T1 measurements were compared with measured or otherwise published axon size measurements in white matter tracts of the rat spinal cord, rat brain, and human brain. RESULTS In both ex vivo and in vivo studies, correlations were present between the relaxation rate 1/T1 and axon size across regions of rat spinal cord with nearly equal myelin content. CONCLUSION While myelination is likely the dominant determinant of T1 in white matter, variations in white matter microstructure, independent of myelin volume fraction, may also be reflected in T1 differences between regions or subjects.
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Affiliation(s)
- Kevin D Harkins
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA
| | - Junzhong Xu
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - Adrienne N Dula
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - Ke Li
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA
| | | | - Daniel F Gochberg
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA.,Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee, USA
| | - John C Gore
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA.,Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee, USA.,Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA.,Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA
| | - Mark D Does
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA.,Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA.,Department of Electrical Engineering, Vanderbilt University, Nashville, Tennessee, USA
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20
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Xu J, Li H, Harkins KD, Jiang X, Xie J, Kang H, Does MD, Gore JC. Mapping mean axon diameter and axonal volume fraction by MRI using temporal diffusion spectroscopy. Neuroimage 2014; 103:10-19. [PMID: 25225002 PMCID: PMC4312203 DOI: 10.1016/j.neuroimage.2014.09.006] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [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: 03/12/2014] [Revised: 09/02/2014] [Accepted: 09/04/2014] [Indexed: 02/01/2023] Open
Abstract
Mapping mean axon diameter and intra-axonal volume fraction may have significant clinical potential because nerve conduction velocity is directly dependent on axon diameter, and several neurodegenerative diseases affect axons of specific sizes and alter axon counts. Diffusion-weighted MRI methods based on the pulsed gradient spin echo (PGSE) sequence have been reported to be able to assess axon diameter and volume fraction non-invasively. However, due to the relatively long diffusion times used, e.g. >20ms, the sensitivity to small axons (diameter<2μm) is low, and the derived mean axon diameter has been reported to be overestimated. In the current study, oscillating gradient spin echo (OGSE) diffusion sequences with variable frequency gradients were used to assess rat spinal white matter tracts with relatively short effective diffusion times (1-5ms). In contrast to previous PGSE-based methods, the extra-axonal diffusion cannot be modeled as hindered (Gaussian) diffusion when short diffusion times are used. Appropriate frequency-dependent rates are therefore incorporated into our analysis and validated by histology-based computer simulation of water diffusion. OGSE data were analyzed to derive mean axon diameters and intra-axonal volume fractions of rat spinal white matter tracts (mean axon diameter of ~1.27-5.54μm). The estimated values were in good agreement with histology, including the small axon diameters (<2.5μm). This study establishes a framework for the quantification of nerve morphology using the OGSE method with high sensitivity to small axons.
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Affiliation(s)
- Junzhong Xu
- Institute of Imaging Science, Vanderbilt University, Nashville, TN 37232, USA; Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN 37232, USA; Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37232, USA.
| | - Hua Li
- Institute of Imaging Science, Vanderbilt University, Nashville, TN 37232, USA; Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37232, USA
| | - Kevin D Harkins
- Institute of Imaging Science, Vanderbilt University, Nashville, TN 37232, USA
| | - Xiaoyu Jiang
- Institute of Imaging Science, Vanderbilt University, Nashville, TN 37232, USA; Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN 37232, USA
| | - Jingping Xie
- Institute of Imaging Science, Vanderbilt University, Nashville, TN 37232, USA; Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN 37232, USA
| | - Hakmook Kang
- Department of Biostatistics, Vanderbilt University, Nashville, TN 37203, USA
| | - Mark D Does
- Institute of Imaging Science, Vanderbilt University, Nashville, TN 37232, USA; Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN 37232, USA; Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37232, USA
| | - John C Gore
- Institute of Imaging Science, Vanderbilt University, Nashville, TN 37232, USA; Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN 37232, USA; Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37232, USA; Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37232, USA; Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
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21
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Abstract
The purpose of this work is to correct for transient gradient waveform errors in magnetic resonance imaging (MRI), whether from eddy currents, group delay, or gradient amplifier nonlinearities, which are known to affect image quality. An iterative method is proposed to minimize error between desired and measured gradient waveforms, whose success does not depend on accurate knowledge of the gradient system impulse response. The method was applied to half-pulse excitation for 2-D ultra-short echo time (UTE) imaging on a small animal MRI system and to spiral 2-D excitation on a human 7T MRI system. Predistorted gradient waveforms reduced temporal signal variation caused by excitation gradient trajectory errors in 2-D UTE, and improved the quality of excitation patterns produced by spiral excitation pulses. Iterative gradient predistortion is useful for minimizing transient gradient errors without requiring accurate characterization of the gradient system impulse response.
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22
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Harkins KD, Horch RA, Does MD. Simple and robust saturation-based slice selection for ultrashort echo time MRI. Magn Reson Med 2014; 73:2204-11. [PMID: 25046136 DOI: 10.1002/mrm.25361] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [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: 03/05/2014] [Revised: 05/06/2014] [Accepted: 06/21/2014] [Indexed: 12/23/2022]
Abstract
PURPOSE To present a new method for localizing signal within a two-dimensional (2D) slice suitable for ultrashort echo time (UTE) imaging, called saturation-based UTE (sat-UTE). The new method digitally subtracts two acquisitions that are nonselectively excited with and without selective saturation of the slice of interest. METHODS Sat-UTE was compared with half-pulse and double-half pulse excited UTE within phantoms, as well as 3D-UTE within ex vivo femur and in vivo tibia. Numerical simulations were also used to quantify the effects of slice profile broadening and signal component amplitudes for quantitative UTE. RESULTS Sat-UTE is robust to suppress out-of-slice signal, and produces short T2 signal decay curves comparable to 3D-UTE, but has a lower signal to noise ratio efficiency compared with other slice-selective methods. CONCLUSION The proposed method is useful for fast, quantitative evaluation of short T2 signals, and is insensitive to gradient performance.
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Affiliation(s)
- Kevin D Harkins
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA
| | - R Adam Horch
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA
| | - Mark D Does
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA.,Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA.,Electrical Engineering, Vanderbilt University, Nashville, Tennessee, USA
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23
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Manhard MK, Horch RA, Harkins KD, Gochberg DF, Nyman JS, Does MD. Validation of quantitative bound- and pore-water imaging in cortical bone. Magn Reson Med 2013; 71:2166-71. [PMID: 23878027 DOI: 10.1002/mrm.24870] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [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: 03/26/2013] [Revised: 05/23/2013] [Accepted: 06/12/2013] [Indexed: 12/22/2022]
Abstract
PURPOSE To implement and validate a previously proposed ultra-short echo time method for measuring collagen-bound- and pore-water concentrations in bone based on their T2 differences. METHODS Clinically compatible ultra-short echo time image sequences for quantitative T2 -based bound and pore-water imaging in bone were implemented and validated on a 3T human scanner and a 4.7T small bore system. Bound- and pore-water images were generating using T2 -selective adiabatic pulses. In both cases, the magnetization preparation was integrated into a three-dimensional ultra-short echo time acquisition, with 16 radial spokes acquired per preparation. Images were acquired from human cadaveric femoral mid-shafts from which isolated bone samples were subsequently extracted for nonimaging analysis using T2 spectroscopic measurements. RESULTS A strong correlation was found between imaging-derived concentrations of bound and pore water and those determined from the isolated bone samples. CONCLUSIONS These studies demonstrate the translation of the previously developed approaches for distinguishing bound and pore water from human cortical bone using practical human MRI constraints of gradient performance and radiofrequency power deposition.
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Affiliation(s)
- Mary Kate Manhard
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA; Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA
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24
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Harkins KD, Valentine WM, Gochberg DF, Does MD. In-vivo multi-exponential T2, magnetization transfer and quantitative histology in a rat model of intramyelinic edema. Neuroimage Clin 2013; 2:810-7. [PMID: 24179832 PMCID: PMC3777678 DOI: 10.1016/j.nicl.2013.06.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Revised: 06/10/2013] [Accepted: 06/12/2013] [Indexed: 11/26/2022]
Abstract
Two MRI methods, multi-exponential analysis of transverse relaxation (MET2) and quantitative magnetization transfer (qMT), were used along with quantitative evaluation of histology in a study of intra-myelinic edema in rat spinal white matter. The results showed a strong linear correlation between a distinct long-T2 signal from MET2 analysis and the edema water volume fraction as measured by histology, although this analysis overestimated the edema water content by ≈ 100% relative to quantitative histological measurements. This overestimation was reasoned to result from the effects of inter-compartmental water exchange on observed transverse relaxation. Commonly studied MRI markers for myelin, the myelin water fraction (from MET2 analysis) and the macromolecular pool size ratio (from qMT analysis) produced results that could not be explained purely by changes in myelin content. The results demonstrate the potential for MET2 analysis as well as the limits of putative myelin markers for characterizing white matter abnormalities involving intra-myelinic edema. We studied a rat model of intra-myelinic edema induced by hexachlorophene ingestion. We used multi-exponential T2 (MET2) and quantitative magnetization transfer MRI. Histology was quantitatively evaluated to measure edema volume and myelin content. MET2 provides a measure that correlates but overestimates with edema volume fraction. MET2 measure of edema is affected by microscopic water dynamics.
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25
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Dortch RD, Harkins KD, Juttukonda MR, Gore JC, Does MD. Characterizing inter-compartmental water exchange in myelinated tissue using relaxation exchange spectroscopy. Magn Reson Med 2012; 70:1450-9. [PMID: 23233414 DOI: 10.1002/mrm.24571] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [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: 09/18/2012] [Revised: 10/16/2012] [Accepted: 10/30/2012] [Indexed: 12/20/2022]
Abstract
PURPOSE To investigate inter-compartmental water exchange in two model myelinated tissues ex vivo using relaxation exchange spectroscopy. METHODS Building upon a previously developed theoretical framework, a three-compartment (myelin, intra-axonal, and extra-axonal water) model of the inversion-recovery prepared relaxation exchange spectroscopy signal was applied in excised rat optic nerve and frog sciatic nerve samples to estimate the water residence time constants in myelin (τmyelin ). RESULTS In the rat optic nerve samples, τmyelin = 138 ± 15 ms (mean ± standard deviation) was estimated. In sciatic nerve, which possesses thicker myelin sheaths than optic nerve, a much longer τmyelin = 2046 ± 140 ms was observed. CONCLUSION Consistent with previous studies in rat spinal cord, the extrapolation of exchange rates in optic nerve to in vivo conditions indicates that τmyelin < 100 ms. This suggests that there is a significant effect of inter-compartmental water exchange on the transverse relaxation of water protons in white matter. The much longer τmyelin values in sciatic nerve supports the postulate that the inter-compartmental water exchange rate is mediated by myelin thickness. Together, these findings point to the potential for MRI methods to probe variations in myelin thickness in white matter.
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Affiliation(s)
- Richard D Dortch
- Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA; Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA
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26
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Russell G, Harkins KD, Secomb TW, Galons JP, Trouard TP. A finite difference method with periodic boundary conditions for simulations of diffusion-weighted magnetic resonance experiments in tissue. Phys Med Biol 2012; 57:N35-46. [PMID: 22297418 DOI: 10.1088/0031-9155/57/4/n35] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
A new finite difference (FD) method for calculating the time evolution of complex transverse magnetization in diffusion-weighted magnetic resonance imaging and spectroscopy experiments is described that incorporates periodic boundary conditions. The new FD method relaxes restrictions on the allowable time step size employed in modeling which can significantly reduce computation time for simulations of large physical extent and allow for more complex, physiologically relevant, geometries to be simulated.
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Affiliation(s)
- Greg Russell
- Department of Physics, University of Arizona, Tucson, AZ, USA
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27
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Harkins KD, Dula AN, Does MD. Effect of intercompartmental water exchange on the apparent myelin water fraction in multiexponential T2 measurements of rat spinal cord. Magn Reson Med 2011; 67:793-800. [PMID: 21713984 DOI: 10.1002/mrm.23053] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2010] [Revised: 05/20/2011] [Accepted: 05/20/2011] [Indexed: 02/05/2023]
Abstract
The myelin water fraction has been used as a quantitative measure of the amount of myelin present in tissue. However, recent work has suggested that intercompartmental exchange of water between myelin and nonmyelin compartments may cause the myelin water fraction to underestimate the true myelin content of tissue. In this work, multiexponential T(2) experiments were performed in vivo within the rat spinal cord, and a wide variation of the myelin water fraction (10-35%) was measured within four rat spinal cord tracts with similar myelin content. A numerical simulation based upon segmented histology images was used to quantitatively account for T(2) variations between tracts. The model predicts that a difference in exchange between the four spinal cord tracts, mediated by a difference in the average axon radius and myelin thickness, is sufficient to account for the variation in myelin water fraction measured in vivo.
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Affiliation(s)
- Kevin D Harkins
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA
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28
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Harkins KD, Galons JP, Divijak JL, Trouard TP. Changes in intracellular water diffusion and energetic metabolism in response to ischemia in perfused C6 rat glioma cells. Magn Reson Med 2011; 66:859-67. [PMID: 21446036 DOI: 10.1002/mrm.22866] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2009] [Accepted: 01/11/2011] [Indexed: 11/09/2022]
Abstract
This work reports results of experiments in hollow-fiber bioreactor C6 glioma cell cultures where the apparent diffusion coefficient (ADC) of intracellular water (iADC) was measured at diffusion times between 0.83 and 40 ms. The experiments were carried out before and after the onset of permanent ischemia. The changes in iADC following ischemia were dependent on the diffusion time employed in the experiment. An ischemia-induced decrease in the iADC was measured at short diffusion times, while at long diffusion times the iADC increased. Decreases in the iADC measured at short diffusion times are interpreted to be a result of a decrease in the intrinsic diffusivity of intracellular water due to energy failure. Increases in iADC measured at long diffusion times, are interpreted to result from cell swelling.
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Affiliation(s)
- Kevin D Harkins
- Department of Biomedical Engineering, University of Arizona, Tucson, Arizona 85721, USA
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29
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Harkins KD, Galons JP, Secomb TW, Trouard TP. Assessment of the effects of cellular tissue properties on ADC measurements by numerical simulation of water diffusion. Magn Reson Med 2010; 62:1414-22. [PMID: 19785014 DOI: 10.1002/mrm.22155] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The apparent diffusion coefficient (ADC), as measured by diffusion-weighted MRI, has proven useful in the diagnosis and evaluation of ischemic stroke. The ADC of tissue water is reduced by 30-50% following ischemia and provides excellent contrast between normal and affected tissue. Despite its clinical utility, there is no consensus on the biophysical mechanism underlying the reduction in ADC. In this work, a numerical simulation of water diffusion is used to predict the effects of cellular tissue properties on experimentally measured ADC. The model indicates that the biophysical mechanisms responsible for changes in ADC postischemia depend upon the time over which diffusion is measured. At short diffusion times, the ADC is dependent upon the intrinsic intracellular diffusivity, while at longer, clinically relevant diffusion times, the ADC is highly dependent upon the cell volume fraction. The model also predicts that at clinically relevant diffusion times, the 30-50% drop in ADC after ischemia can be accounted for by cell swelling alone when intracellular T(2) is allowed to be shorter than extracellular T(2).
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Affiliation(s)
- Kevin D Harkins
- Biomedical Engineering Program, University of Arizona, Tucson, Arizona 85721, USA
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30
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Abstract
Diffusion-weighted MRI is commonly used in the diagnosis and evaluation of ischemic stroke because of the rapid decrease observed in the apparent diffusion coefficient (ADC) of tissue water following ischemia. Although this observation has been clinically useful for many years, the biophysical mechanisms underlying the reduction of tissue ADC are still unknown. To help elucidate these mechanisms, we have employed a novel three-dimensional (3D) hollow-fiber bioreactor (HFBR) perfused cell culture system that enables cells to be grown to high density and studied via MRI and MRS. By infusing contrast media into the HFBR, signals from intracellular water and extracellular water are spectroscopically resolved and can be investigated individually. Diffusion measurements carried out on C6 glioma HFBR cell cultures indicate that ischemia-induced cellular swelling results in an increase in the ADC of intracellular water from 0.35 microm(2)/ms to approximately 0.5 microm(2)/ms (diffusion time = 25 ms).
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Affiliation(s)
- Theodore P Trouard
- Biomedical Engineering Program, University of Arizona, Tucson, Arizona 85721-0240, USA.
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