3D magnetization transfer (MT) for the visualization of cardiac free-running Purkinje fibers: an ex vivo proof of concept

Abstract Objectives We investigate the possibility to exploit high-field MRI to acquire 3D images of Purkinje network which plays a crucial role in cardiac function. Since Purkinje fibers (PF) have a distinct cellular structure and are surrounded by connective tissue, we investigated conventional contrast mechanisms along with the magnetization transfer (MT) imaging technique to improve image contrast between ventricular structures of differing macromolecular content. Methods Three fixed porcine ventricular samples were used with free-running PFs on the endocardium. T1, T2*, T2, and M0 were evaluated on 2D slices for each sample at 9.4 T. MT parameters were optimized using hard pulses with different amplitudes, offset frequencies and durations. The cardiac structure was assessed through 2D and 3D T1w images with isotropic resolutions of 150 µm. Histology, immunofluorescence, and qPCR were performed to analyze collagen contents of cardiac tissue and PF. Results An MT preparation module of 350 ms duration inserted into the sequence with a B1 = 10 µT and frequency offset = 3000 Hz showed the best contrast, approximately 0.4 between PFs and myocardium. Magnetization transfer ratio (MTR) appeared higher in the cardiac tissue (MTR = 44.7 ± 3.5%) than in the PFs (MTR = 25.2 ± 6.3%). Discussion MT significantly improves contrast between PFs and ventricular myocardium and appears promising for imaging the 3D architecture of the Purkinje network.

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A fast B1-mapping method for the correction and normalization of magnetization transfer ratio maps at 3 T

NeuroImage ◽

10.1016/j.neuroimage.2009.11.054 ◽

2010 ◽

Vol 49 (4) ◽

pp. 3015-3026 ◽

Cited By ~ 52

Author(s):

Steffen Volz ◽

Ulrike Nöth ◽

Anna Rotarska-Jagiela ◽

Ralf Deichmann

Keyword(s):

Magnetization Transfer ◽

Mapping Method ◽

Magnetization Transfer Ratio ◽

Transfer Ratio ◽

B1 Mapping

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Cervical cord magnetization transfer ratio and clinical changes over 18 months in patients with relapsing-remitting multiple sclerosis: a preliminary study

Multiple Sclerosis Journal ◽

10.1177/1352458506070714 ◽

2006 ◽

Vol 12 (5) ◽

pp. 662-665 ◽

Cited By ~ 18

Author(s):

A Charil ◽

D Caputo ◽

R Cavarretta ◽

M P Sormani ◽

P Ferrante ◽

...

Keyword(s):

Multiple Sclerosis ◽

Relapse Rate ◽

Magnetization Transfer ◽

Small Sample ◽

Cervical Cord ◽

Magnetization Transfer Ratio ◽

Short Term ◽

Disease Evolution ◽

Transfer Ratio ◽

Relapsing Remitting

Background Magnetization transfer ratio (MTR) permits the quantitative estimation of cervical cord tissue damage in patients with multiple sclerosis (MS). Objective To determine whether a single time-point MTR scan of the cervical cord is associated with short-term disease evolution in patients with relapsing-remitting (RR) MS. Methods Using a 1.5-T magnetic resonance imaging (MRI) system with a tailored cervical cord phased array coil, fast short-tau inversion recovery (fast-STIR) and MTR scans were obtained from 14 untreated patients with RRMS at baseline. Cervical cord MTR histograms were derived. Over the 18- month follow-up period, relapse rate was measured and disability assessed by the Expanded Disability Status Scale (EDSS) score. Results Average cervical cord MTR was correlated with relapse rate ( r= -0.56, P = 0.037). A moderate correlation ( r values ranging from -0.33 to -0.36) between baseline cervical cord MTR metrics and EDSS changes over 18 months was also noted, albeit statistical significance was not reached ( P = 0.26 and 0.21, respectively) perhaps because of the relatively small sample size. Conclusions This study suggests that a ‘snapshot’ MT MRI assessment of the cervical cord may detect cervical cord tissue changes associated with short-term disease evolution in RRMS.

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Measurement of magnetization transfer ratio (MTR) from cervical spinal cord: Multicenter reproducibility and variability

Journal of Magnetic Resonance Imaging ◽

10.1002/jmri.26537 ◽

2018 ◽

Vol 49 (6) ◽

pp. 1777-1785 ◽

Cited By ~ 1

Author(s):

Benoit Combès ◽

Laureline Monteau ◽

Elise Bannier ◽

Virginie Callot ◽

Pierre Labauge ◽

...

Keyword(s):

Spinal Cord ◽

Cervical Spinal Cord ◽

Magnetization Transfer ◽

Magnetization Transfer Ratio ◽

Transfer Ratio

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1159Electrical isolation by electroporation of right ventricular myocardium in an ex-vivo beating porcine heart: a potential novel use of the alert internal cardioversion catheter

EP Europace ◽

10.1093/ehjci/eux152.007 ◽

2017 ◽

Vol 19 (suppl_3) ◽

pp. iii246-iii246

Author(s):

GO. Furniss ◽

I. Rankin ◽

GA. Haywood

Keyword(s):

Right Ventricular ◽

Ex Vivo ◽

Ventricular Myocardium ◽

Porcine Heart ◽

Internal Cardioversion

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ILEX PARAGUARIENSIS, EXERCISE AND CARDIOPROTECTION: A retrospective analysis

10.1101/452946 ◽

2018 ◽

Author(s):

Fábio Cahuê ◽

José Hamilton Matheus Nascimento ◽

Luciane Barcellos ◽

Veronica P. Salerno

Keyword(s):

Data Science ◽

Molecular Mechanisms ◽

Cardiac Tissue ◽

Ex Vivo ◽

Ischemia Reperfusion ◽

Ilex Paraguariensis ◽

Ros Generation ◽

Yerba Mate ◽

Reductive Stress ◽

Apparent Loss

AbstractStudies on strategies to generate cardioprotective effects have been on the rise. Previous work by our group with an ex vivo model of ischemia/reperfusion has shown that both the short-term consumption of yerba mate and exercise can each induce protection of cardiac function independently. Surprising, the two strategies together do not, with an apparent loss of their respective cardioprotection activity. To improve our understanding of the mechanisms involved without reperforming the experiments, we have conducted a retrospective data science-analysis that have produced new insights. The analysis shows that yerba mate generated reductive stress. Alone, this stress increased redox damage in the heart that appears to have led to a protective conditioning. In combination with exercise, the effects of mate inhibited the intermittent ROS generation promoted by exercise alone, which diminished the adaptive response in the heart. These results suggest that an understanding of the molecular mechanisms involved with the yerba mate-promoted reductive stress in cardiac tissue could lead to improved strategies to induce cardioprotection.

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Ln(iii)-complexes of a DOTA analogue with an ethylenediamine pendant arm as pH-responsive PARACEST contrast agents

Dalton Transactions ◽

10.1039/c5dt04443j ◽

2016 ◽

Vol 45 (8) ◽

pp. 3486-3496 ◽

Cited By ~ 8

Author(s):

T. Krchová ◽

A. Gálisová ◽

D. Jirák ◽

P. Hermann ◽

J. Kotek

Keyword(s):

Contrast Agents ◽

Magnetization Transfer ◽

Magnetization Transfer Ratio ◽

Ph Responsive ◽

Resonance Imaging ◽

Biologically Relevant ◽

Pendant Arm ◽

Ratio Approach ◽

Magnetic Resonance Imaging Mri ◽

Ph Range

New contrast agents useful for pH determination (in the biologically relevant pH range) by Magnetic Resonance Imaging (MRI) using magnetization transfer ratio approach are presented.

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The role of dye affinity in optical measurements of Cai2+ transients in cardiac muscle

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00751.2013 ◽

2014 ◽

Vol 307 (1) ◽

pp. H73-H79 ◽

Cited By ~ 7

Author(s):

Wei Kong ◽

Vladimir G. Fast

Keyword(s):

Optical Fibers ◽

Cardiac Tissue ◽

Ventricular Myocardium ◽

Left Ventricular ◽

Optical Measurements ◽

Neonatal Rat ◽

High Affinity ◽

Cycle Lengths ◽

Rat Myocytes

Previous experiments in cultures of neonatal rat myocytes demonstrated that the shape of Cai2+ transients measured using high-affinity Ca2+-sensitive dyes may be misrepresented. The purpose of this study was to examine the role of dye affinity in Cai2+ measurements in intact adult cardiac tissue by comparing optical recordings obtained with high- and low-affinity dyes. Experiments were carried out in porcine left ventricular (LV) wedge preparations stained locally by intramural injection via microcapillaries (diameter = 150 μm) with a low-affinity Ca2+-sensitive dye Fluo-4FF or Fluo-2LA (nominal Kd, ∼7–10 μmol/l), high-affinity dye Rhod-2 ( Kd = 0.57 μmol/l), and Fluo-4 or Fluo-2MA ( Kd, ∼0.4 μmol/l); in addition, tissue was stained with transmembrane potential ( Vm)-sensitive dye RH-237. Optical recordings of Vm and Cai2+ were made using optical fibers (diameter = 325 μm) glued with the microcapillaries. The durations of Cai2+ transients measured at 50% level of recovery (CaD50) using high-affinity Fluo-4/Fluo-2MA dyes were up to ∼81% longer than those measured with low-affinity Fluo-4FF/Fluo-2LA at long pacing cycle lengths (CL). In Fluo-4/Fluo-2MA measurements at long CLs, Cai2+ transients often (∼50% of cases) exhibited slow upstroke rise and extended plateau. In Rhod-2 measurements, CaD50 was moderately longer (up to ∼35%) than in Fluo-4FF recordings, but Cai2+ transient shapes were similar. In all series of measurements, mean action potential duration values were not significantly different ( P > 0.05). The delays between Vm and Cai2+ upstrokes were comparable for low- and high-affinity dyes ( P > 0.05). In conclusion, measurements of Cai2+ transient in ventricular myocardium are strongly affected by the affinity of Ca2+ dyes. The high-affinity dyes may overestimate the duration and alter the shape of Cai2+ transients.

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Magnetization Transfer Ratio in Peripheral Nerve Tissue

Investigative Radiology ◽

10.1097/rli.0000000000000455 ◽

2018 ◽

Vol 53 (7) ◽

pp. 397-402 ◽

Cited By ~ 10

Author(s):

Jennifer Kollmer ◽

Thorsten Kästel ◽

Johann M.E. Jende ◽

Martin Bendszus ◽

Sabine Heiland

Keyword(s):

Peripheral Nerve ◽

Magnetization Transfer ◽

Nerve Tissue ◽

Magnetization Transfer Ratio ◽

Transfer Ratio

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Multiparametric MRI detects longitudinal evolution of folic acid-induced nephropathy in mice

AJP Renal Physiology ◽

10.1152/ajprenal.00128.2018 ◽

2018 ◽

Vol 315 (5) ◽

pp. F1252-F1260 ◽

Cited By ~ 5

Author(s):

Kai Jiang ◽

Tristan A. Ponzo ◽

Hui Tang ◽

Prasanna K. Mishra ◽

Slobodan I. Macura ◽

...

Keyword(s):

Folic Acid ◽

Interstitial Fibrosis ◽

Magnetization Transfer ◽

Kidney Injury ◽

Multiparametric Mri ◽

Magnetization Transfer Ratio ◽

Kidney Volume ◽

Kidney Size ◽

Functional Changes

The rodent model of folic acid (FA)-induced acute kidney injury (AKI) provides a useful model for studying human AKI, but little is known about longitudinal changes in renal hemodynamics and evolution of renal fibrosis in vivo. In this work, we aimed to longitudinally assess renal structural and functional changes using multiparametric magnetic resonance imaging (MRI). Ten adult mice were injected with FA, after which a multiparametric MRI was used to measure kidney volume, hypoxia index R2*, magnetization transfer ratio (MTR), perfusion, T1, and glomerular filtration rate (GFR) at 2 wk posttreatment. Then five mice were euthanized for histology, and the other five underwent MRI again at 4 wk, followed by histology. Control mice ( n = 5) were injected with vehicle and studied with MRI at 2 wk. Trichrome and hematoxylin-eosin staining were performed to assess FA-induced tissue injuries. Whereas kidney size and oxygenation showed progressive deterioration, a transient impairment in renal perfusion and normalized GFR slightly improved by 4 wk. Kidney fluid content, as reflected by T1, was prominent at 2 wk and tended to regress at 4 wk, consistent with observed tubular dilation. Trichrome staining revealed patchy necrosis and mild interstitial fibrosis at 2 wk, which exacerbated at 4 wk. MTR detected increased fibrosis at 4 wk. In conclusion, multiparametric MRI captured the longitudinal progression in kidney damage evolving within the first month after treatment with folic acid and may provide a useful tool for assessment of therapeutic strategies.

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