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Kellman P, Xue H, Chow K, Spottiswoode BS, Arai AE, Thompson RB. Optimized saturation recovery protocols for T1-mapping in the heart: influence of sampling strategies on precision. J Cardiovasc Magn Reson 2014; 16:55. [PMID: 25190004 PMCID: PMC4244052 DOI: 10.1186/s12968-014-0055-3] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Accepted: 07/09/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND T1-mapping has the potential to detect and quantify diffuse processes such as interstitial fibrosis. Detection of disease at an early stage by measurement of subtle changes requires a high degree of reproducibility. Initial implementation of saturation recovery (SR) T1-mapping employed 3-parameter fitting which was highly accurate but was quite sensitive to noise; 2-parameter fitting greatly reduced the sensitivity to noise at the expense of a small degree of systematic bias. A recently introduced implementation that uses a variable readout flip angle greatly reduces systematic errors in T1-measurement thereby making it feasible to use SR methods with 2-parameter fitting with improved accuracy and precision. SR T1 mapping techniques with multi-heartbeat recovery times have been proposed to better sample the T1 recovery curve, but have not been evaluated for 2-parameter fitting. METHODS An analytic formulation for calculating the standard deviation (SD) for SR T1-mapping with 2-parameter fitting is developed and validated using Monte-Carlo simulation. The coefficient of variation is compared for a brute force optimization of sampling and for several previously described sampling schemes for T1 measurement over several uncertainty ranges. Experimental validation is performed in phantoms over a range of T1, and in-vivo both native and post-contrast. Pixel-wise SD maps are calculated for SR T1-mapping. RESULTS Sampling schemes that use a non-saturated anchor image and multiple (N) measurements at a single fixed saturation delay are found to be near optimum for the case of known T1 and are close to the brute force optimized solution over wide ranges of native and post-contrast T1 values. The fixed delay sampling scheme is simple to implement and provides an improvement over uniformly distributed schemes. CONCLUSIONS Sampling strategies for saturation recovery methods for myocardial T1-mapping have been optimized and validated experimentally. Reduced SD, or improved precision, may be achieved by using fixed saturation delays when considering native myocardium and post-contrast T1 ranges. Pixel-wise estimates of T1 mapping errors have been formulated and validated for SR fitting methods.
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Parekh K, Rigsby CK, deFreitas RA, Spottiswoode BS, Markl M. Quantitative non-contrast T1 mapping of left ventricle in children and young adults. J Cardiovasc Magn Reson 2014. [PMCID: PMC4045832 DOI: 10.1186/1532-429x-16-s1-p268] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
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Chow K, Spottiswoode BS, Pagano JJ, Thompson RB. Improved precision in SASHA T1 mapping with a variable flip angle readout. J Cardiovasc Magn Reson 2014. [PMCID: PMC4043358 DOI: 10.1186/1532-429x-16-s1-m9] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Shao J, Natsuaki Y, Spottiswoode BS, Hu P. Instantaneous Signal Loss simulation (InSiL) - an alternative algorithm for myocardial T1 mapping using the MOLLI sequence. JOURNAL OF CARDIOVASCULAR MAGNETIC RESONANCE 2014. [PMCID: PMC4043513 DOI: 10.1186/1532-429x-16-s1-p26] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Smith PM, Daruwalla V, Freed BH, Spottiswoode BS, Kalisz K, Carr JC, Collins JD. Myocardial strain analysis in patients with Heart Failure with preserved Ejection Fraction using bright blood cine MR images: A comparison with speckle-tracking echocardiography. J Cardiovasc Magn Reson 2014. [PMCID: PMC4042354 DOI: 10.1186/1532-429x-16-s1-p71] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Auger DA, Zhong X, Epstein FH, Meintjes EM, Spottiswoode BS. Semi-automated left ventricular segmentation based on a guide point model approach for 3D cine DENSE cardiovascular magnetic resonance. J Cardiovasc Magn Reson 2014; 16:8. [PMID: 24423129 PMCID: PMC3903450 DOI: 10.1186/1532-429x-16-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Accepted: 12/03/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The most time consuming and limiting step in three dimensional (3D) cine displacement encoding with stimulated echoes (DENSE) MR image analysis is the demarcation of the left ventricle (LV) from its surrounding anatomical structures. The aim of this study is to implement a semi-automated segmentation algorithm for 3D cine DENSE CMR using a guide point model approach. METHODS A 3D mathematical model is fitted to guide points which were interactively placed along the LV borders at a single time frame. An algorithm is presented to robustly propagate LV epicardial and endocardial surfaces of the model using the displacement information encoded in the phase images of DENSE data. The accuracy, precision and efficiency of the algorithm are tested. RESULTS The model-defined contours show good accuracy when compared to the corresponding manually defined contours as similarity coefficients Dice and Jaccard consist of values above 0.7, while false positive and false negative measures show low percentage values. This is based on a measure of segmentation error on intra- and inter-observer spatial overlap variability. The segmentation algorithm offers a 10-fold reduction in the time required to identify LV epicardial and endocardial borders for a single 3D DENSE data set. CONCLUSION A semi-automated segmentation method has been developed for 3D cine DENSE CMR. The algorithm allows for contouring of the first cardiac frame where blood-myocardium contrast is almost nonexistent and reduces the time required to segment a 3D DENSE data set significantly.
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Allen BD, Carr M, Zenge MO, Schmidt M, Nadar MS, Spottiswoode BS, Collins JD, Carr JC. Clinical evaluation of accelerated cardiac cine imaging using iterative k-t-sparse SENSE. J Cardiovasc Magn Reson 2014. [PMCID: PMC4044287 DOI: 10.1186/1532-429x-16-s1-w13] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Smith PM, Freed BH, Allen BD, Spottiswoode BS, Carr M, Wasielewski M, Campione K, Schmidt M, Nadar MS, Zenge MO, Carr JC, Collins JD. Biventricular strain analysis at 1.5T cardiac MR imaging: preliminary results in volunteers using an iterative SENSE reconstruction with L1 regularization. J Cardiovasc Magn Reson 2014. [PMCID: PMC4044769 DOI: 10.1186/1532-429x-16-s1-p62] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Ferreira P, Kilner PJ, McGill LA, Nielles-Vallespin S, Scott AD, Spottiswoode BS, Zhong X, Ho SY, McCarthy K, Ismail T, Gatehouse P, Silva R, Lyon A, Prasad SK, Firmin D, Pennell DJ. Aberrant myocardial sheetlet mobility in hypertrophic cardiomyopathy detected using in vivo cardiovascular magnetic resonance diffusion tensor imaging. J Cardiovasc Magn Reson 2014. [PMCID: PMC4044463 DOI: 10.1186/1532-429x-16-s1-p338] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Allen BD, Carr M, Zenge MO, Schmidt M, Nadar MS, Spottiswoode BS, Collins JD, Carr JC. Evaluation of accelerated real-time CMR using sparse sampling with iterative SENSE reconstruction in patients and volunteers. J Cardiovasc Magn Reson 2014. [PMCID: PMC4044417 DOI: 10.1186/1532-429x-16-s1-o12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Flanagan O, Spottiswoode BS, Carr M, Collins JD, Bi X, Botelho M, Ayache JB, Edelman RR, Carr JC. The validity of a free breathing motion corrected phase sensitive inversion recovery sequence in the detection of delayed myocardial enhancement in non-ischemic heart disease. J Cardiovasc Magn Reson 2014. [PMCID: PMC4044998 DOI: 10.1186/1532-429x-16-s1-p305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Smith PM, Freed BH, Allen BD, Spottiswoode BS, Carr M, Wasielewski M, Campione K, Cordts M, Guetter C, Jolly MP, Schmidt M, Nadar MS, Zenge MO, Carr JC, Collins JD. Biventricular strain analysis at 1.5T cardiac MR imaging: preliminary results in volunteers using an iterative SENSE reconstruction with L1 regularization. J Cardiovasc Magn Reson 2014. [PMCID: PMC4045056 DOI: 10.1186/1532-429x-16-s1-w4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Alam MH, Baksi AJ, He T, Smith GC, Izgi C, Wage R, Drivas P, Greiser A, Spottiswoode BS, Firmin D, Pennell DJ. Validation of Siemens T2* inline WIP package for quantification of cardiac and hepatic iron loading at 1.5T and 3T. J Cardiovasc Magn Reson 2014. [PMCID: PMC4043195 DOI: 10.1186/1532-429x-16-s1-p323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Semaan E, Spottiswoode BS, Freed B, Stankovic Z, Allen BD, Carr M, Wasielewski M, Campione K, Shah S, Carr JC, Markl M, Collins JD. High-resolution modified look-locker inversion recovery (HR-MOLLI) for RV extracellular volume fraction at 3T and 1.5T: A feasibility study. J Cardiovasc Magn Reson 2014. [PMCID: PMC4044445 DOI: 10.1186/1532-429x-16-s1-p159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Collins JD, Sommerville L, Föll D, Magrath P, Spottiswoode BS, Freed BH, Carr JC, Markl M. Regional left ventricular myocardial T1 and velocity mapping: elevated extracellular volume fraction is associated with altered myocardial velocities. J Cardiovasc Magn Reson 2014. [PMCID: PMC4044316 DOI: 10.1186/1532-429x-16-s1-p5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Sirry MS, Davies NH, Kadner K, Dubuis L, Saleh MG, Meintjes EM, Spottiswoode BS, Zilla P, Franz T. Micro-structurally detailed model of a therapeutic hydrogel injectate in a rat biventricular cardiac geometry for computational simulations. Comput Methods Biomech Biomed Engin 2013; 18:325-31. [PMID: 23682845 DOI: 10.1080/10255842.2013.793765] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Biomaterial injection-based therapies have showed cautious success in restoration of cardiac function and prevention of adverse remodelling into heart failure after myocardial infarction (MI). However, the underlying mechanisms are not well understood. Computational studies utilised simplified representations of the therapeutic myocardial injectates. Wistar rats underwent experimental infarction followed by immediate injection of polyethylene glycol hydrogel in the infarct region. Hearts were explanted, cryo-sectioned and the region with the injectate histologically analysed. Histological micrographs were used to reconstruct the dispersed hydrogel injectate. Cardiac magnetic resonance imaging data from a healthy rat were used to obtain an end-diastolic biventricular geometry which was subsequently adjusted and combined with the injectate model. The computational geometry of the injectate exhibited microscopic structural details found the in situ. The combination of injectate and cardiac geometry provides realistic geometries for multiscale computational studies of intra-myocardial injectate therapies for the rat model that has been widely used for MI research.
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Spottiswoode BS, van den Heever DJ, Chang Y, Engelhardt S, Du Plessis S, Nicolls F, Hartzenberg HB, Gretschel A. Preoperative three-dimensional model creation of magnetic resonance brain images as a tool to assist neurosurgical planning. Stereotact Funct Neurosurg 2013; 91:162-9. [PMID: 23446024 DOI: 10.1159/000345264] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Accepted: 10/15/2012] [Indexed: 11/19/2022]
Abstract
BACKGROUND Neurosurgeons regularly plan their surgery using magnetic resonance imaging (MRI) images, which may show a clear distinction between the area to be resected and the surrounding healthy brain tissue depending on the nature of the pathology. However, this distinction is often unclear with the naked eye during the surgical intervention, and it may be difficult to infer depth and an accurate volumetric interpretation from a series of MRI image slices. OBJECTIVES In this work, MRI data are used to create affordable patient-specific 3-dimensional (3D) scale models of the brain which clearly indicate the location and extent of a tumour relative to brain surface features and important adjacent structures. METHODS This is achieved using custom software and rapid prototyping. In addition, functionally eloquent areas identified using functional MRI are integrated into the 3D models. RESULTS Preliminary in vivo results are presented for 2 patients. The accuracy of the technique was estimated both theoretically and by printing a geometrical phantom, with mean dimensional errors of less than 0.5 mm observed. CONCLUSIONS This may provide a practical and cost-effective tool which can be used for training, and during neurosurgical planning and intervention.
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Ahmed F, Spottiswoode BS, Carey PD, Stein DJ, Seedat S. Relationship between neurocognition and regional brain volumes in traumatized adolescents with and without posttraumatic stress disorder. Neuropsychobiology 2013; 66:174-84. [PMID: 22948482 DOI: 10.1159/000339558] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Accepted: 05/21/2012] [Indexed: 11/19/2022]
Abstract
OBJECTIVES Studies using convergent neurocognitive and structural imaging paradigms in adolescent posttraumatic stress disorder (PTSD) are limited; in the current study we used both voxel-based morphometry (VBM) to obtain between-group volumetric differences, and Freesurfer to examine the relationship between cognition and regional brain volumes. METHODS Participants were 21 traumatized adolescents with PTSD matched with 32 traumatized adolescents without PTSD. Magnetic resonance images were obtained on a 1.5-Tesla MAGNETOM Siemens Symphony scanner. VBM implemented on FSL was then used to compare between-group grey matter volumes, after which Freesurfer was used to obtain global volume and thickness measurements in different brain regions. RESULTS Significant between-group neurocognitive differences were found for tests of attention, delayed recall and visual reconstruction. On VBM, reduced grey matter was found in three regions in the PTSD group: left insula, right precuneus and right cingulate gyrus, using uncorrected values (p < 0.001), while no statistically significant between-group differences were found on the initial Freesurfer stream. Further Freesurfer analysis on Qdec revealed significant reductions in the insula for the PTSD group. In addition, volumetric changes in the corpus callosum and insula were significantly associated with deficits in logical memory and visual reproduction on Freesurfer analysis. CONCLUSIONS Trauma exposure of itself may be sufficient to cause structural changes in adolescents regardless of PTSD development.
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Andronikou S, Spottiswoode BS, Tomazos N. A semi-automated method for measuring thickness and white matter integrity of the corpus callosum. SA J Radiol 2012. [DOI: 10.4102/sajr.v16i4.257] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Aim. Diseases affecting cerebral white matter may lead to left-right asymmetries and atrophy of interhemispheric connections, i.e. the corpus callosum (CC). Our aim was to describe and test a semi-automated system that divides the midline CC into a number of segments and determines thickness at each, then performs fibre tracking from these segments.
Methods. Six normal female volunteers (average age 25.8 ±6.7 years) and a female patient with diagnosed multiple sclerosis (age 26 years) were scanned on a 3T MRI. We performed diffusion-weighted imaging in 12 directions, and calculated diffusion tensors and fractional anisotropy (FA) maps from this pre-processed data. Fibre tracking from a region-of-interest encompassing the entire CC was done. This fibre data, together with FA maps and the unweighted diffusion tensor imaging (DTI) image (b = 0 s/mm2), were imported into a custom tool written in MATLAB. The midline sagittal position was carefully defined by selecting multiple midline points in coronal and axial views and rotating the image volume and fibre co-ordinates accordingly. Using the customised tool, dorsal and ventral CC contours were manually drawn on the mid-sagittal FA image, initiating automated calculation of a contour midway between these manually drawn lines. The programme was designed to then divide the midline contour into a pre-selected number of segments; from each segment border, perpendicular spokes were projected until they intersected with the dorsal and ventral contours. This technique divided the CC into a pre-set amount of segments, the number of which was limited by the spatial resolution. It was decided to set the number at 40 to ensure that each segment depicted a contiguous strip of voxels across the CC from the dorsal to the ventral contour. The system allows these segments to then be used as seeds for separate fibre tracking in each cerebral hemisphere, and various parameters are automatically plotted as a function of distance along the midline contour. The following parameters are measurable: midline CC thickness; midline FA; fibre volume for each hemisphere (represented as a left/right ratio centred on zero) and mean fibre FA for each hemisphere (also represented as a left/right ratio centred on zero).
Results. The tool proved successful in measuring and plotting CC midline thickness and FA, but was not sensitive for peripheral white matter lesions.
Conclusions. The technique successfully determined values of CC midline thickness, FA and interhemispheric differences. Future research will determine normal values for age and compare CC thickness with peripheral white matter volume loss in large groups of patients, using the semiautomated technique.
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Spottiswoode BS, Du Plessis S, Gretschel A, Lotz JW. Functional MRI in pre-surgical planning: Case study and cautionary notes. SA J Radiol 2012. [DOI: 10.4102/sajr.v16i3.293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Background. Since its inception almost 20 years ago, functional magnetic resonance imaging (fMRI) has greatly advanced our knowledge of human brain function. Although the clinical applications of fMRI are still limited, there have recently been encouraging advances for its use in pre-operative functional cortical mapping to identify potentially eloquent areas prior to neurosurgery.
Objectives. We explore the potential use of this emerging technique by presenting a neurosurgical case study, as performed at the Cape Universities Brain Imaging Centre (CUBIC), Tygerberg, Cape Town. We conclude with a brief summary of the potential pitfalls of this technique, as well as cautionary guidelines based on our experience.
Methods and results. A 22-year-old male patient from Tygerberg Hospital underwent the successful resection of an anaplastic astrocytoma after fMRI presurgical planning at our facility. The subject was able to leave the ward unassisted.
Conclusion. If consideration is given to the many limitations of this emerging technique, fMRI can be useful in aiding the neurosurgeon in pre-operative planning of his surgical approach.
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Auger DA, Zhong X, Epstein FH, Spottiswoode BS. Mapping right ventricular myocardial mechanics using 3D cine DENSE cardiovascular magnetic resonance. J Cardiovasc Magn Reson 2012; 14:4. [PMID: 22236389 PMCID: PMC3311142 DOI: 10.1186/1532-429x-14-4] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2011] [Accepted: 01/11/2012] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND The mechanics of the right ventricle (RV) are not well understood as studies of the RV have been limited. This is, in part, due to the RV's thin wall, asymmetric geometry and irregular motion. However, the RV plays an important role in cardiovascular function. This study aims to describe the complex mechanics of the healthy RV using three dimensional (3D) cine displacement encoding with stimulated echoes (DENSE) cardiovascular magnetic resonance (CMR). METHODS Whole heart 3D cine DENSE data were acquired from five healthy volunteers. Tailored post-processing algorithms for RV mid-wall tissue tracking and strain estimation are presented. A method for sub-dividing the RV into four regions according to anatomical land marks is proposed, and the temporal evolution of strain was assessed in these regions. RESULTS The 3D cine DENSE tissue tracking methods successfully capture the motion and deformation of the RV at a high spatial resolution in all volunteers. The regional Lagrangian peak surface strain and time to peak values correspond with previous studies using myocardial tagging, DENSE and strain encoded CMR. The inflow region consistently displays lower peak strains than the apical and outflow regions, and the time to peak strains suggest RV mechanical activation in the following order: inflow, outflow, mid, then apex. CONCLUSIONS Model-free techniques have been developed to study the myocardial mechanics of the RV at a high spatial resolution using 3D cine DENSE CMR. The consistency of the regional RV strain patterns across healthy subjects is encouraging and the techniques may have clinical utility in assessing disrupted RV mechanics in the diseased heart.
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Zhong X, Gibberman LB, Spottiswoode BS, Gilliam AD, Meyer CH, French BA, Epstein FH. Comprehensive cardiovascular magnetic resonance of myocardial mechanics in mice using three-dimensional cine DENSE. J Cardiovasc Magn Reson 2011; 13:83. [PMID: 22208954 PMCID: PMC3278394 DOI: 10.1186/1532-429x-13-83] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Accepted: 12/30/2011] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Quantitative noninvasive imaging of myocardial mechanics in mice enables studies of the roles of individual genes in cardiac function. We sought to develop comprehensive three-dimensional methods for imaging myocardial mechanics in mice. METHODS A 3D cine DENSE pulse sequence was implemented on a 7T small-bore scanner. The sequence used three-point phase cycling for artifact suppression and a stack-of-spirals k-space trajectory for efficient data acquisition. A semi-automatic 2D method was adapted for 3D image segmentation, and automated 3D methods to calculate strain, twist, and torsion were employed. A scan protocol that covered the majority of the left ventricle in a scan time of less than 25 minutes was developed, and seven healthy C57Bl/6 mice were studied. RESULTS Using these methods, multiphase normal and shear strains were measured, as were myocardial twist and torsion. Peak end-systolic values for the normal strains at the mid-ventricular level were 0.29 ± 0.17, -0.13 ± 0.03, and -0.18 ± 0.14 for E(rr), E(cc), and E(ll), respectively. Peak end-systolic values for the shear strains were 0.00 ± 0.08, 0.04 ± 0.12, and 0.03 ± 0.07 for E(rc), E(rl), and E(cl), respectively. The peak end-systolic normalized torsion was 5.6 ± 0.9°. CONCLUSIONS Using a 3D cine DENSE sequence tailored for cardiac imaging in mice at 7 T, a comprehensive assessment of 3D myocardial mechanics can be achieved with a scan time of less than 25 minutes and an image analysis time of approximately 1 hour.
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Auger DA, Zhong X, Meintjes EM, Epstein FH, Spottiswoode BS. Quantifying right ventricular motion and strain using 3D cine DENSE MRI. J Cardiovasc Magn Reson 2011. [PMCID: PMC3106615 DOI: 10.1186/1532-429x-13-s1-m3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Zhong X, Spottiswoode BS, Meyer CH, Epstein FH. Comparison of SNR efficiencies and strain for cine DENSE using conventional EPI, flyback EPI and spiral k-space trajectories. J Cardiovasc Magn Reson 2011. [PMCID: PMC3106891 DOI: 10.1186/1532-429x-13-s1-p58] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Spottiswoode BS, Meintjes EM, Anderson AW, Molteno CD, Stanton ME, Dodge NC, Gore JC, Peterson BS, Jacobson JL, Jacobson SW. Diffusion tensor imaging of the cerebellum and eyeblink conditioning in fetal alcohol spectrum disorder. Alcohol Clin Exp Res 2011; 35:2174-83. [PMID: 21790667 DOI: 10.1111/j.1530-0277.2011.01566.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Prenatal alcohol exposure is related to a wide range of neurocognitive effects. Eyeblink conditioning (EBC), which involves temporal pairing of a conditioned with an unconditioned stimulus, has been shown to be a potential biomarker of fetal alcohol exposure. A growing body of evidence suggests that white matter may be a specific target of alcohol teratogenesis, and the neural circuitry underlying EBC is known to involve the cerebellar peduncles. Diffusion tensor imaging (DTI) is a magnetic resonance imaging (MRI) technique that has proven useful for assessing central nervous system white matter integrity. This study used DTI to examine the degree to which the fetal alcohol-related deficit in EBC may be mediated by structural impairment in the cerebellar peduncles. METHODS Thirteen children with fetal alcohol spectrum disorder (FASD) and 12 matched controls were scanned using DTI and structural MRI sequences. The DTI data were processed using a voxelwise technique, and the structural data were used for volumetric analyses. Prenatal alcohol exposure group and EBC performance were examined in relation to brain volumes and outputs from the DTI analysis. RESULTS Fractional anisotropy (FA) and perpendicular diffusivity group differences between alcohol-exposed and nonexposed children were identified in the left middle cerebellar peduncle. Alcohol exposure correlated with lower FA and greater perpendicular diffusivity in this region, and these correlations remained significant even after controlling for total brain and cerebellar volumes. Conversely, trace conditioning performance was related to higher FA and lower perpendicular diffusivity in the left middle peduncle. The effect of prenatal alcohol exposure on trace conditioning was partially mediated by lower FA in this region. CONCLUSIONS This study extends recent findings that have used DTI to reveal microstructural deficits in white matter in children with FASD. This is the first DTI study to demonstrate mediation of a fetal alcohol-related effect on neuropsychological function by deficits in white matter integrity.
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