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 Magnetic Resonance Materials in Physics, Biology and Medicine   [SJR: 0.787]   [H-I: 46]   [3 followers]  Follow         Hybrid journal (It can contain Open Access articles)    ISSN (Print) 0968-5243 - ISSN (Online) 1352-8661    Published by Springer-Verlag  [2351 journals]
• An 8-channel Tx/Rx dipole array combined with 16 Rx loops for
high-resolution functional cardiac imaging at 7 T
• Authors: Bart R. Steensma; Ingmar J. Voogt; Tim Leiner; Peter R. Luijten; Jesse Habets; Dennis W. J. Klomp; Cornelis A. T. van den Berg; Alexander J. E. Raaijmakers
Pages: 7 - 18
Abstract: Objective To demonstrate imaging performance for cardiac MR imaging at 7 T using a coil array of 8 transmit/receive dipole antennas and 16 receive loops. Materials and methods An 8-channel dipole array was extended by adding 16 receive-only loops. Average power constraints were determined by electromagnetic simulations. Cine imaging was performed on eight healthy subjects. Geometrical factor (g-factor) maps were calculated to assess acceleration performance. Signal-to-noise ratio (SNR)-scaled images were reconstructed for different combinations of receive channels, to demonstrate the SNR benefits of combining loops and dipoles. Results The overall image quality of the cardiac functional images was rated a 2.6 on a 4-point scale by two experienced radiologists. Imaging results at different acceleration factors demonstrate that acceleration factors up to 6 could be obtained while keeping the average g-factor below 1.27. SNR maps demonstrate that combining loops and dipoles provides a more than 50% enhancement of the SNR in the heart, compared to a situation where only loops or dipoles are used. Conclusion This work demonstrates the performance of a combined loop/dipole array for cardiac imaging at 7 T. With this array, acceleration factors of 6 are possible without increasing the average g-factor in the heart beyond 1.27. Combining loops and dipoles in receive mode enhances the SNR compared to receiving with loops or dipoles only.
PubDate: 2018-02-01
DOI: 10.1007/s10334-017-0665-5
Issue No: Vol. 31, No. 1 (2018)

• Single-breath-hold 3-D CINE imaging of the left ventricle using Cartesian
sampling
• Authors: Jens Wetzl; Michaela Schmidt; François Pontana; Benjamin Longère; Felix Lugauer; Andreas Maier; Joachim Hornegger; Christoph Forman
Pages: 19 - 31
Abstract: Objectives Our objectives were to evaluate a single-breath-hold approach for Cartesian 3-D CINE imaging of the left ventricle with a nearly isotropic resolution of $$1.9 \times 1.9 \times 2.5\,{\text {mm}^3}$$ and a breath-hold duration of $$\sim$$ 19 s against a standard stack of 2-D CINE slices acquired in multiple breath-holds. Validation is performed with data sets from ten healthy volunteers. Materials and methods A Cartesian sampling pattern based on the spiral phyllotaxis and a compressed sensing reconstruction method are proposed to allow 3-D CINE imaging with high acceleration factors. The fully integrated reconstruction uses multiple graphics processing units to speed up the reconstruction. The 2-D CINE and 3-D CINE are compared based on ventricular function parameters, contrast-to-noise ratio and edge sharpness measurements. Results Visual comparisons of corresponding short-axis slices of 2-D and 3-D CINE show an excellent match, while 3-D CINE also allows reformatting to other orientations. Ventricular function parameters do not significantly differ from values based on 2-D CINE imaging. Reconstruction times are below 4 min. Conclusion We demonstrate single-breath-hold 3-D CINE imaging in volunteers and three example patient cases, which features fast reconstruction and allows reformatting to arbitrary orientations.
PubDate: 2018-02-01
DOI: 10.1007/s10334-017-0624-1
Issue No: Vol. 31, No. 1 (2018)

• Segmental biventricular analysis of myocardial function using high
temporal and spatial resolution tissue phase mapping
• Authors: Marius Menza; Daniela Föll; Jürgen Hennig; Bernd Jung
Pages: 61 - 73
Abstract: Objective Myocardial dysfunction of the right ventricle (RV) is an important indicator of RV diseases, e.g. RV infarction or pulmonary hypertension. Tissue phase mapping (TPM) has been widely used to determine function of the left ventricle (LV) by analyzing myocardial velocities. The analysis of RV motion is more complicated due to the different geometry and smaller wall thickness. The aim of this work was to adapt and optimize TPM to the demands of the RV. Materials and methods TPM measurements were acquired in 25 healthy volunteers using a velocity-encoded phase-contrast sequence and kt-accelerated parallel imaging in combination with optimized navigator strategy and blood saturation. Post processing was extended by a 10-segment RV model and a detailed biventricular analysis of myocardial velocities was performed. Results High spatio-temporal resolution (1.0 × 1.0 × 6 mm3, 21.3 ms) and the optimized blood saturation enabled good delineation of the RV and its velocities. Global and segmental velocities, as well as time to peak velocities showed significant differences between the LV and RV. Furthermore, complex timing of the RV could be demonstrated by segmental time to peak analysis. Conclusion High spatio-temporal resolution TPM enables a detailed biventricular analysis of myocardial motion and might provide a reliable tool for description and detection of diseases affecting left and right ventricular function.
PubDate: 2018-02-01
DOI: 10.1007/s10334-017-0661-9
Issue No: Vol. 31, No. 1 (2018)

• State-of-the-art review: stress T1 mapping—technical considerations,
pitfalls and emerging clinical applications
• Authors: Stefan K. Piechnik; Stefan Neubauer; Vanessa M. Ferreira
Pages: 131 - 141
Abstract: In vivo mapping of the myocardial T1 relaxation time has recently attained wide clinical validation of its potential utility. In this review, we address the basic principles of the T1 mapping techniques, with particular attention to the emerging application of vasodilatory stress agents to interrogate the myocardial microvascular compartment, and differences between commonly used T1 mapping methods when applied in clinical practice.
PubDate: 2018-02-01
DOI: 10.1007/s10334-017-0649-5
Issue No: Vol. 31, No. 1 (2018)

• Towards accurate and precise T 1 and extracellular volume mapping in the
myocardium: a guide to current pitfalls and their solutions
• Authors: Donnie Cameron; Vassilios S. Vassiliou; David M. Higgins; Peter D. Gatehouse
Pages: 143 - 163
Abstract: Mapping of the longitudinal relaxation time (T 1) and extracellular volume (ECV) offers a means of identifying pathological changes in myocardial tissue, including diffuse changes that may be invisible to existing T 1-weighted methods. This technique has recently shown strong clinical utility for pathologies such as Anderson-Fabry disease and amyloidosis and has generated clinical interest as a possible means of detecting small changes in diffuse fibrosis; however, scatter in T 1 and ECV estimates offers challenges for detecting these changes, and bias limits comparisons between sites and vendors. There are several technical and physiological pitfalls that influence the accuracy (bias) and precision (repeatability) of T 1 and ECV mapping methods. The goal of this review is to describe the most significant of these, and detail current solutions, in order to aid scientists and clinicians to maximise the utility of T 1 mapping in their clinical or research setting. A detailed summary of technical and physiological factors, issues relating to contrast agents, and specific disease-related issues is provided, along with some considerations on the future directions of the field.
PubDate: 2018-02-01
DOI: 10.1007/s10334-017-0631-2
Issue No: Vol. 31, No. 1 (2018)

• In vitro evaluation of flow patterns and turbulent kinetic energy in
trans-catheter aortic valve prostheses
• Authors: Daniel Giese; Kilian Weiss; Bettina Baeßler; Navid Madershahian; Yeong-Hoon Choi; David Maintz; Alexander C. Bunck
Pages: 165 - 172
Abstract: Objectives The objective of the current work was to evaluate flow and turbulent kinetic energy in different transcatheter aortic valve implants using highly undersampled time-resolved multi-point 3-directional phase-contrast measurements (4D Flow MRI) in an in vitro setup. Materials and methods A pulsatile flow setup was used with a compliant tubing mimicking a stiff left ventricular outflow tract and ascending aorta. Five different implants were measured using a highly undersampled multi-point 4D Flow MRI sequence. Velocities and turbulent kinetic energy values were analysed and compared. Results Strong variations of turbulent kinetic energy distributions between the valves were observed. Maximum turbulent kinetic energy values ranged from 100 to over 500 J/m3 while through-plane velocities were similar between all valves. Conclusion Highly accelerated 4D Flow MRI for the measurement of velocities and turbulent kinetic energy values allowed for the assessment of hemodynamic parameters in five different implant models. The presented setup, measurement protocol and analysis methods provides an efficient approach to compare different valve implants and could aid future novel valve designs.
PubDate: 2018-02-01
DOI: 10.1007/s10334-017-0651-y
Issue No: Vol. 31, No. 1 (2018)

• Sex, body mass index, and blood pressure are related to aortic
characteristics in healthy, young adults using magnetic resonance vessel
wall imaging: the AMBITYON study
• Authors: Anouk L. M. Eikendal; Hester M. den Ruijter; Cees Haaring; Tobias Saam; Rob J. van der Geest; Jos J. M. Westenberg; Michiel L. Bots; Imo E. Hoefer; Tim Leiner
Pages: 173 - 182
Abstract: Objectives More detailed evaluation of atherosclerosis and its key determinants in young individuals is warranted to improve knowledge on the pathophysiology of its development and progression. This study evaluated associations of magnetic resonance imaging (MRI)-derived aortic wall area, wall thickness, and pulse wave velocity (PWV) with cardiovascular risk factors in asymptomatic, young adults. Materials and methods In 124 adults (age: 25–35 years) from the general population-based Atherosclerosis Monitoring and Biomarker Measurements in the Young study, demography, anthropometry, and blood samples were collected. The studied MRI-parameters were measured using a 3.0T MRI system. Relations between cardiovascular risk factors and aortic characteristics were assessed using multivariable linear regression analyses. Results Mean age was 31.8 years, 47.6% was male. Aortic wall area was positively associated with age [β = 0.01, (95% confidence interval (CI) 2.00 × 10−3, 0.02), p = 0.01] and BMI [β = 0.01, (0.01, 0.02), p = 0.003] and negatively associated with sex (reference: men) [β = −0.06, (−0.11, −0.01), p = 0.02]. Natural logarithm transformed (ln) aortic wall thickness was positively associated with BMI [β = 0.01, (1.00 × 10−3, 0.02), p = 0.02]. Ln aortic PWV was positively associated with 10 mmHg increment of SBP [β = 0.06, (0.03, 0.09), p < 0.001] and DBP [β = 0.06, (0.02, 0.09), p = 0.006]. No relations were observed for smoking and lipids. Conclusions Already in early adulthood, aortic wall geometry and stiffness vary by age, sex, BMI, and blood pressure.
PubDate: 2018-02-01
DOI: 10.1007/s10334-017-0626-z
Issue No: Vol. 31, No. 1 (2018)

• Three-dimensional black-blood multi-contrast carotid imaging using
compressed sensing: a repeatability study
• Authors: Jianmin Yuan; Ammara Usman; Scott A. Reid; Kevin F. King; Andrew J. Patterson; Jonathan H. Gillard; Martin J. Graves
Pages: 183 - 190
Abstract: Objective The purpose of this work is to evaluate the repeatability of a compressed sensing (CS) accelerated multi-contrast carotid protocol at 3 T. Materials and methods Twelve volunteers and eight patients with carotid disease were scanned on a 3 T MRI scanner using a CS accelerated 3-D black-blood multi-contrast protocol which comprises T 1w, T 2w and PDw without CS, and with a CS factor of 1.5 and 2.0. The volunteers were scanned twice, the lumen/wall area and wall thickness were measured for each scan. Eight patients were scanned once, the inter/intra-observer reproducibility of the measurements was calculated. Results In the repeated volunteer scans, the interclass correlation coefficient (ICC) for the wall area measurement using a CS factor of 1.5 in PDw, T 1w and T 2w were 0.95, 0.81, and 0.97, respectively. The ICC for lumen area measurement using a CS factor of 1.5 in PDw, T 1w and T 2w were 0.96, 0.92, and 0.96, respectively. In patients, the ICC for inter/intra-observer measurements of lumen/wall area, and wall thickness were all above 0.81 in all sequences. Conclusion The results show a CS accelerated 3-D black-blood multi-contrast protocol is a robust and reproducible method for carotid imaging. Future protocol design could use CS to reduce the scanning time.
PubDate: 2018-02-01
DOI: 10.1007/s10334-017-0640-1
Issue No: Vol. 31, No. 1 (2018)

• Relationship between carotid plaque surface morphology and perfusion: a 3D
DCE-MRI study
• Authors: Jianmin Yuan; Gregory Makris; Andrew Patterson; Ammara Usman; Tilak Das; Andrew Priest; Zhongzhao Teng; Sarah Hilborne; Dario Prudencio; Jonathan Gillard; Martin Graves
Pages: 191 - 199
Abstract: Objective This study aims to explore the relationship between plaque surface morphology and neovascularization using a high temporal and spatial resolution 4D contrast-enhanced MRI/MRA sequence. Materials and methods Twenty one patients with either recent symptoms or a carotid artery stenosis ≥40% were recruited in this study. Plaque surface morphology and luminal stenosis were determined from the arterial phase MRA images. Carotid neovascularization was evaluated by a previously validated pharmacokinetic (PK) modeling approach. K trans (transfer constant) and v p (partial plasma volume) were calculated in both the adventitia and plaque. Results Image acquisition and analysis was successfully performed in 28 arteries. Mean luminal stenosis was 44% (range 11–82%). Both adventitial and plaque K trans in ulcerated/irregular plaques were significantly higher than smooth plaques (0.079 ± 0.018 vs. 0.064 ± 0.011 min−1, p = 0.02; 0.065 ± 0.013 vs. 0.055 ± 0.010 min−1, p = 0.03, respectively). Positive correlations between adventitial K trans and v p against stenosis were observed (r = 0.44, p = 0.02; r = 0.55, p = 0.01, respectively). Conclusion This study demonstrates the feasibility of using a single sequence to acquire both high resolution 4D CE-MRA and DCE-MRI to evaluate both plaque surface morphology and function. The results demonstrate significant relationships between lumen surface morphology and neovascularization.
PubDate: 2018-02-01
DOI: 10.1007/s10334-017-0621-4
Issue No: Vol. 31, No. 1 (2018)

• Vessel wall characterization using quantitative MRI: what’s in a
number'
• Authors: Bram F. Coolen; Claudia Calcagno; Pim van Ooij; Zahi A. Fayad; Gustav J. Strijkers; Aart J. Nederveen
Pages: 201 - 222
Abstract: The past decade has witnessed the rapid development of new MRI technology for vessel wall imaging. Today, with advances in MRI hardware and pulse sequences, quantitative MRI of the vessel wall represents a real alternative to conventional qualitative imaging, which is hindered by significant intra- and inter-observer variability. Quantitative MRI can measure several important morphological and functional characteristics of the vessel wall. This review provides a detailed introduction to novel quantitative MRI methods for measuring vessel wall dimensions, plaque composition and permeability, endothelial shear stress and wall stiffness. Together, these methods show the versatility of non-invasive quantitative MRI for probing vascular disease at several stages. These quantitative MRI biomarkers can play an important role in the context of both treatment response monitoring and risk prediction. Given the rapid developments in scan acceleration techniques and novel image reconstruction, we foresee the possibility of integrating the acquisition of multiple quantitative vessel wall parameters within a single scan session.
PubDate: 2018-02-01
DOI: 10.1007/s10334-017-0644-x
Issue No: Vol. 31, No. 1 (2018)

• Evaluation of retained products of conception using pulsed continuous
arterial spin-labeling MRI: clinical feasibility and initial results
• Authors: Nobuyuki Kosaka; Yasuhiro Fujiwara; Tetsuji Kurokawa; Tsuyoshi Matsuda; Masayuki Kanamoto; Naoyuki Takei; Kenji Takata; Jin Takahashi; Yoshio Yoshida; Hirohiko Kimura
Abstract: Objectives We evaluated the vascularity of retained products of conception (RPOC) using arterial spin-labeling magnetic resonance imaging (ASL-MRI) to clarify the clinical feasibility of this approach. Materials and methods A pulsed-continuous ASL sequence with echo-planar imaging (EPI) acquisitions was used. Ten consecutive patients with RPOC were enrolled. All ASL images were evaluated visually and semiquantitatively and compared with the findings of Doppler ultrasound (US) and dynamic contrast-enhanced MRI (DCE-MRI). Results The technical success rate was 93.7% (15/16 scans). One failed case was excluded from the analysis. Six patients showed quite high signals over RPOC, while three patients showed no abnormal signals. Doppler US alone failed to detect the hypervascular area in two cases, and ASL-MRI alone failed in three. A significant linear correlation was found between semiquantitative values of ASL-MRI and DCE-MRI. All six patients showing high signals on ASL-MRI underwent follow-up MRI after therapy. High signals in five patients decreased visually and semiquantitatively, while one patient showed signal increases. Conclusion Evaluation of RPOC using ASL-MRI was clinically feasible and response to therapy could be evaluated. However, the clinical advantages over conventional imaging remain unclear and need to be evaluated.
PubDate: 2018-03-16
DOI: 10.1007/s10334-018-0681-0

• Toward faster inference of micron-scale axon diameters using Monte Carlo
simulations
• Authors: Morgan Mercredi; Melanie Martin
Abstract: Object Recent advances have allowed oscillating gradient (OG) diffusion MRI to infer the sizes of micron-scale axon diameters. Here the effects on the precision of the inferred diameters are studied when reducing the number of images collected to reduce imaging time for clinical feasibility. Materials and methods Monte Carlo simulations of cosine OG sequences (50–1000 Hz) using a two-compartment model on a parallel cylinder (diameters 1–5 μm) geometry were conducted. Temporal diffusion spectroscopy was used to infer axon diameters. Three different gradient sets were simulated with different combinations of gradient strengths. Results Five frequencies were adequate for d = 3–5 μm with single-sized cylinders and for effective mean axon diameters greater than 2 μm for cylinders with a distributions of diameters. There was some improvement in precision for d = 1–2 μm with 10 frequencies. It is better to repeat measurements at higher gradient strengths than to use a range of gradient strengths. The improvement tended to be greatest when using fewer frequencies and was especially noticeable at very high gradient strengths. Conclusion Images can be collected with fewer gradient strengths and frequencies without sacrificing the precision of the measurements. This could be useful in reducing imaging time so that OG techniques can be used in clinical settings.
PubDate: 2018-03-07
DOI: 10.1007/s10334-018-0680-1

• Vessel radius mapping in an extended model of transverse relaxation
• Authors: Lukas Reinhold Buschle; Christian H. Ziener; Ke Zhang; Volker J. F. Sturm; Thomas Kampf; Artur Hahn; Gergely Solecki; Frank Winkler; Martin Bendszus; Sabine Heiland; Heinz-Peter Schlemmer; Felix T. Kurz
Abstract: Objectives Spin dephasing of the local magnetization in blood vessel networks can be described in the static dephasing regime (where diffusion effects may be ignored) by the established model of Yablonskiy and Haacke. However, for small capillary radii, diffusion phenomena for spin-bearing particles are not negligible. Material and methods In this work, we include diffusion effects for a set of randomly distributed capillaries and provide analytical expressions for the transverse relaxation times T2* and T2 in the strong collision approximation and the Gaussian approximation that relate MR signal properties with microstructural parameters such as the mean local capillary radius. Results Theoretical results are numerically validated with random walk simulations and are used to calculate capillary radius distribution maps for glioblastoma mouse brains at 9.4 T. For representative tumor regions, the capillary maps reveal a relative increase of mean radius for tumor tissue towards healthy brain tissue of $$128 \pm 23 \%$$ (p < 0.001). Conclusion The presented method may be used to quantify angiogenesis or the effects of antiangiogenic therapy in tumors whose growth is associated with significant microvascular changes.
PubDate: 2018-02-24
DOI: 10.1007/s10334-018-0677-9

• Gestational and lactational exposure to dichlorinated bisphenol A induces
early alterations of hepatic lipid composition in mice
• Authors: Dounia El Hamrani; Amandine Chepied; William Même; Marc Mesnil; Norah Defamie; Sandra Même
Abstract: Objective Using non-invasive magnetic resonance (MR) techniques and a histological approach, we assessed the outcomes of perinatal exposure at a low dose of 3,3′-DCBPA (2-chloro-4-[1-(3-chloro-4-hydroxyphenyl)-1-methylethyl]phenol) and/or 3,5-DCBPA (2,6-dichloro-4-[1-(4-hydroxyphenyl)-1-methylethyl]phenol) on mice livers. Materials and methods Fertilized female Swiss mice were injected intraperitoneally during gestation and lactation with either vehicle control, 20 μg/kg/day of BPA, 3,5-DCBPA, 3,3′-DCBPA or a mixture (mix-DCBPA). Complementary methods were used to evaluate, in male and female pups, (1) liver structure by texture analysis of images obtained through MR imaging (MRI) and histology, (2) hepatic lipid composition through in vivo 1H MR spectroscopy (1H MRS). Results Principal component analysis of texture parameters showed no structural modification of the liver with BPA and DCBPA treatments. Accordingly, no hepatic microvesicular steatosis was observed through hematoxylin–eosin staining. Compared to control, MRS revealed no difference in lipid composition for BPA, 3,5-DCBPA or 3,3′-DCBPA groups. However, MRS detected a significant increase in the mix-DCBPA groups for the saturated component of fatty acids (FA), total unsaturated FA bond index and polyunsaturated FA bond index. Conclusion Prior to any structural changes, polyunsaturated fatty acids significantly increased in young male and female mice exposed perinatally at a low dose to a mixture of dichlorinated BPA.
PubDate: 2018-02-20
DOI: 10.1007/s10334-018-0679-7

• The impact of fibre orientation on T 1 -relaxation and apparent tissue
water content in white matter
• Authors: Felix Schyboll; Uwe Jaekel; Bernd Weber; Heiko Neeb
Abstract: Objective Recent MRI studies have shown that the orientation of nerve fibres relative to the main magnetic field affects the R2*(= 1/T2*) relaxation rate in white matter (WM) structures. The underlying physical causes have been discussed in several studies but are still not completely understood. However, understanding these effects in detail is of great importance since this might serve as a basis for the development of new diagnostic tools and/or improve quantitative susceptibility mapping techniques. Therefore, in addition to the known angular dependence of R2*, the current study investigates the relationship between fibre orientation and the longitudinal relaxation rate, R1 (= 1/T1), as well as the apparent water content. Materials and methods For a group of 16 healthy subjects, a series of gradient echo, echo-planar and diffusion weighted images were acquired at 3T from which the decay rates, the apparent water content and the diffusion direction were reconstructed. The diffusion weighted data were used to determine the angle between the principle fibre direction and the main magnetic field to examine the angular dependence of R1 and apparent water content. Results The obtained results demonstrate that both parameters depend on the fibre orientation and exhibit a positive correlation with the angle between fibre direction and main magnetic field. Conclusion These observations could be helpful to improve and/or constrain existing biophysical models of brain microstructure by imposing additional constraints resulting from the observed angular dependence R1 and apparent water content in white matter.
PubDate: 2018-02-20
DOI: 10.1007/s10334-018-0678-8

• Advances in cardiovascular MR imaging
• Authors: Tim Leiner; Gustav Strijkers
PubDate: 2018-02-06
DOI: 10.1007/s10334-018-0676-x

• Segmentation and texture analysis of structural biomarkers using

• Authors: Manohar Latha; Ganesan Kavitha
Abstract: Objective Schizophrenia (SZ) is a psychiatric disorder that especially affects individuals during their adolescence. There is a need to study the subanatomical regions of SZ brain on magnetic resonance images (MRI) based on morphometry. In this work, an attempt was made to analyze alterations in structure and texture patterns in images of the SZ brain using the level-set method and Laws texture features. Materials and methods T1-weighted MRI of the brain from Center of Biomedical Research Excellence (COBRE) database were considered for analysis. Segmentation was carried out using the level-set method. Geometrical and Laws texture features were extracted from the segmented brain stem, corpus callosum, cerebellum, and ventricle regions to analyze pattern changes in SZ. Results The level-set method segmented multiple brain regions, with higher similarity and correlation values compared with an optimized method. The geometric features obtained from regions of the corpus callosum and ventricle showed significant variation (p < 0.00001) between normal and SZ brain. Laws texture feature identified a heterogeneous appearance in the brain stem, corpus callosum and ventricular regions, and features from the brain stem were correlated with Positive and Negative Syndrome Scale (PANSS) score (p < 0.005). Conclusion A framework of geometric and Laws texture features obtained from brain subregions can be used as a supplement for diagnosis of psychiatric disorders.
PubDate: 2018-02-03
DOI: 10.1007/s10334-018-0674-z

• Introductory editorial
• Authors: David Norris
PubDate: 2018-01-08
DOI: 10.1007/s10334-017-0672-6

• Cardiac magnetic resonance T1 and extracellular volume mapping with motion
correction and co-registration based on fast elastic image registration
• Authors: Shuo Zhang; Thu Thao Le; Sven Kabus; Boyang Su; Derek J. Hausenloy; Stuart A. Cook; Calvin W. L. Chin; Ru San Tan
Abstract: Objective Our aim was to investigate the technical feasibility of a novel motion compensation method for cardiac magntic resonance (MR) T1 and extracellular volume fraction (ECV) mapping. Materials and methods Native and post-contrast T1 maps were obtained using modified look-locker inversion recovery (MOLLI) pulse sequences with acquisition scheme defined in seconds. A nonrigid, nonparametric, fast elastic registration method was applied to generate motion-corrected T1 maps and subsequently ECV maps. Qualitative rating was performed based on T1 fitting-error maps and overlay images. Local deformation vector fields were produced for quantitative assessment. Intra- and inter-observer reproducibility were compared with and without motion compensation. Results Eighty-two T1 and 39 ECV maps were obtained in 21 patients with diverse myocardial diseases. Approximately 60% demonstrated clear quality improvement after motion correction for T1 mapping, particularly for the poor-rating cases (23% before vs 2% after). Approximately 67% showed further improvement with co-registration in ECV mapping. Although T1 and ECV values were not clinically significantly different before and after motion compensation, there was improved intra- and inter-observer reproducibility after motion compensation. Conclusions Automated motion correction and co-registration improved the qualitative assessment and reproducibility of cardiac MR T1 and ECV measurements, allowing for more reliable ECV mapping.
PubDate: 2017-12-21
DOI: 10.1007/s10334-017-0668-2

• 3D true-phase polarity recovery with independent phase estimation using
three-tier stacks based region growing (3D-TRIPS)
• Authors: Haining Liu; Gregory J. Wilson; Niranjan Balu; Jeffrey H. Maki; Daniel S. Hippe; Wei Wu; Hiroko Watase; Jinnan Wang; Martin L. Gunn; Chun Yuan
Abstract: Objectives A postprocessing technique termed 3D true-phase polarity recovery with independent phase estimation using three-tier stacks based region growing (3D-TRIPS) was developed, which directly reconstructs phase-sensitive inversion-recovery images without acquisition of phase-reference images. The utility of this technique is demonstrated in myocardial late gadolinium enhancement (LGE) imaging. Materials and methods A data structure with three tiers of stacks was used for 3D-TRIPS to directly achieve reliable region growing for successful background-phase estimation. Fifteen patients undergoing postgadolinium 3D phase-sensitive inversion recovery (PSIR) cardiac LGE magnetic resonance imaging (MRI) were recruited, and 3D-TRIPS LGE reconstructions were compared with standard PSIR. Objective voxel-by-voxel comparison was performed. Additionally, blinded review by two radiologists compared scar visibility, clinical acceptability, voxel polarity error, or groups and blurring. Results 3D-TRIPS efficiently reconstructed postcontrast phase-sensitive myocardial LGE images. Objective analysis showed an average 95% voxel-by-voxel agreement between 3D-TRIPS and PSIR images. Blinded radiologist review demonstrated similar image quality between 3D-TRIPS and PSIR reconstruction. Conclusion 3D-TRIPS provided similar image quality to PSIR for phase-sensitive myocardial LGE MRI reconstruction. 3D-TRIPS does not require acquisition of a reference image and can therefore be used to accelerate phase-sensitive LGE imaging.
PubDate: 2017-12-07
DOI: 10.1007/s10334-017-0666-4

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