3D spatio-temporal analysis for compressive sensing in magnetic resonance imaging of the murine cardiac cycle

2013 ◽  
Author(s):  
Brice Hirst ◽  
Yahong R. Zheng ◽  
Ming Yang ◽  
Lixin Ma
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Compressive Sensing ◽  
Cardiac Cycle ◽  
Temporal Analysis ◽  
Resonance Imaging ◽  
Spatio Temporal

scholarly journals Extent and spatial distribution of left atrial arrhythmogenic sites, late gadolinium enhancement at magnetic resonance imaging, and low-voltage areas in patients with persistent atrial fibrillation: comparison of imaging vs. electrical parameters of fibrosis and arrhythmogenesis

EP Europace ◽  
2019 ◽  
Vol 21 (10) ◽  
pp. 1484-1493 ◽  
Author(s):  
Juan Chen ◽  
Thomas Arentz ◽  
Hubert Cochet ◽  
Björn Müller-Edenborn ◽  
Steven Kim ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Atrial Fibrillation ◽  
Magnetic Resonance ◽  
Left Atrial ◽  
Low Voltage ◽  
Spatial Relationship ◽  
Delayed Enhancement ◽  
Resonance Imaging ◽  
Spatio Temporal ◽  
Temporal Dispersion

Abstract Aims Atrial fibrosis contributes to arrhythmogenesis in atrial fibrillation and can be detected by MRI or electrophysiological mapping. The current study compares the spatial correlation between delayed enhancement (DE) areas to low-voltage areas (LVAs) and to arrhythmogenic areas with spatio-temporal dispersion (ST-Disp) or continuous activity (CA) in atrial fibrillation (AF). Methods and results Sixteen patients with persistent AF (nine long-standing) underwent DE-magnetic resonance imaging (1.25 mm × 1.25 mm × 2.5 mm) prior to pulmonary vein isolation. Left atrial (LA) voltage mapping was acquired in AF and the regional activation patterns of 7680 AF wavelets were analysed. Sites with ST-Disp or CA were characterized (voltage, duration) and their spatial relationship to DE areas and LVAs <0.5 mV was assessed. Delayed enhancement areas and LVAs covered 55% and 24% (P < 0.01) of total LA surface, respectively. Delayed enhancement area was present at 61% of LVAs, whereas low voltage was present at 28% of DE areas. Most DE areas (72%) overlapped with atrial high-voltage areas (>0.5 mV). Spatio-temporal dispersion and CA more frequently co-localized with LVAs than with DE areas (78% vs. 63%, P = 0.02). Regional bipolar voltage of ST-Disp vs. CA was 0.64 ± 0.47 mV vs. 0.58 ± 0.51 mV. All 28 ST-Disp and 56 CA areas contained electrograms with prolonged duration (115 ± 14 ms) displaying low voltage (0.34 ± 0.11 mV). Conclusion A small portion of DE areas and LVAs harbour the arrhythmogenic areas displaying ST-Disp or CA. Most arrhythmogenic activities co-localized with LVAs, while there was less co-localization with DE areas. There is an important mismatch between DE areas and LVAs which needs to be considered when used as target for catheter ablation.

Noninvasive intracranial compliance and pressure based on dynamic magnetic resonance imaging of blood flow and cerebrospinal fluid flow: review of principles, implementation, and other noninvasive approaches

2003 ◽  
Vol 14 (4) ◽  
pp. 1-8 ◽  
Author(s):  
Patricia B. Raksin ◽  
Noam Alperin ◽  
Anusha Sivaramakrishnan ◽  
Sushma Surapaneni ◽  
Terry Lichtor
Keyword(s):  
Magnetic Resonance Imaging ◽  
Cerebrospinal Fluid ◽  
Magnetic Resonance ◽  
Cardiac Cycle ◽  
Venous Blood ◽  
Pressure Probe ◽  
Intracranial Volume ◽  
Resonance Imaging ◽  
Intracranial Compliance ◽  
Arterial Blood

Current techniques for intracranial pressure (ICP) measurement are invasive. All require a surgical procedure for placement of a pressure probe in the central nervous system and, as such, are associated with risk and morbidity. These considerations have driven investigators to develop noninvasive techniques for pressure estimation. A recently developed magnetic resonance (MR) imaging–based method to measure intracranial compliance and pressure is described. In this method the small changes in intracranial volume and ICP that occur naturally with each cardiac cycle are considered. The pressure change during the cardiac cycle is derived from the cerebrospinal fluid (CSF) pressure gradient waveform calculated from the CSF velocities. The intracranial volume change is determined by the instantaneous differences between arterial blood inflow, venous blood outflow, and CSF volumetric flow rates into and out of the cranial vault. Elastance (the inverse of compliance) is derived from the ratio of the measured pressure and volume changes. A mean ICP value is then derived based on a linear relationship that exists between intracranial elastance and ICP. The method has been validated in baboons, flow phantoms, and computer simulations. To date studies in humans demonstrate good measurement reproducibility and reliability. Several other noninvasive approaches for ICP measurement, mostly nonimaging based, are also reviewed. Magnetic resonance imaging–based ICP measurement may prove valuable in the diagnosis and serial evaluation of patients with a variety of disorders associated with alterations in ICP.

scholarly journals Analyses of displacement of the heart and its substructures caused by cardiac movement and identification of compensatory margins based on breath-hold electrocardiograph-gated 4-dimensional magnetic resonance imaging for oesophageal radiotherapy

2020 ◽  
Author(s):  
Guanghui Yang ◽  
Chengrui Fu ◽  
Guanzhong Gong ◽  
Jing Zhang ◽  
Qian Wang ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Papillary Muscle ◽  
Cardiac Cycle ◽  
Left Ventricular ◽  
Breath Hold ◽  
Resonance Imaging ◽  
4D Mri ◽  
Planning Ct ◽  
Anterior Posterior

Abstract Background: Cardiac movement can affect the accuracy of the evaluation of the location of heart and its substructures by planning computed tomography (CT). We aimed to measure the margin displacement and calculate compensatory margins through breath-hold electrocardiograph (ECG)-gated 4-dimensional magnetic resonance imaging (4D-MRI) for oesophageal radiotherapy.Methods: The study enrolled 10 patients with oesophageal radiotherapy plans and pretreatment 4D-MRI data. The displacement of the heart and its substructures was measured between the end of the systolic and diastolic phases in one cardiac cycle. The compensatory margins were calculated by extending the planning CT to cover the internal target volume (ITV) of all structures. Differences between groups were tested with the Kruskal-Wallis H test.Results: The extent of movement of the heart and its substructures during one cardiac cycle were approximately 4.0-26.1 mm in the anterior-posterior (AP),left-right (LR), and cranial-caudal (CC) axes, and the compensatory margins should be applied to the planning CT by extending the margins by 1.7, 3.6, 1.8, 3.0, 2.1, and 2.9 mm for the pericardium, 1.2, 2.5, 1.0, 2.8, 1.8, and 3.3 mm for the heart, 3.8, 3.4, 3.1, 2.8, 0.9, and 2.0 mm for the interatrial septum, 3.3, 4.9, 2.0, 4.1, 1.1, and 2.9 mm for the interventricular septum, 2.2, 3.0, 1.1, 5.3, 1.8, and 2.4 mm for the left ventricular muscle (LVM), 5.9, 3.4, 2.1, 6.1, 5.4, and 3.6 mm for the antero-lateral papillary muscle (ALPM), and 6.6, 2.9, 2.6, 6.6, 3.9, and 4.8 mm for the postero-medial papillary muscle (PMPM) in the anterior, posterior, left, right, cranial, and caudal directions.Conclusions: The locations of the heart and its substructures determined by planning CT were not able to represent the true positions due to cardiac movement, and compensatory margins can be applied to decrease the influence of movement.

scholarly journals The evaluation of the aortic annulus displacement during cardiac cycle using magnetic resonance imaging

2018 ◽  
Vol 18 (1) ◽  
Author(s):  
Tomasz Plonek ◽  
Mikolaj Berezowski ◽  
Jacek Kurcz ◽  
Przemyslaw Podgorski ◽  
Marek Sąsiadek ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Cardiac Cycle ◽  
Aortic Annulus ◽  
Resonance Imaging

Quantification of left and right ventricular kinetic energy using four-dimensional intracardiac magnetic resonance imaging flow measurements

2012 ◽  
Vol 302 (4) ◽  
pp. H893-H900 ◽  
Author(s):  
M. Carlsson ◽  
E. Heiberg ◽  
J. Toger ◽  
H. Arheden
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Kinetic Energy ◽  
Cardiac Cycle ◽  
Peak Exercise ◽  
Diastolic Filling ◽  
Resonance Imaging ◽  
External Work ◽  
Flow Measurements ◽  
Early Diastole

We aimed to quantify kinetic energy (KE) during the entire cardiac cycle of the left ventricle (LV) and right ventricle (RV) using four-dimensional phase-contrast magnetic resonance imaging (MRI). KE was quantified in healthy volunteers ( n = 9) using an in-house developed software. Mean KE through the cardiac cycle of the LV and the RV were highly correlated ( r2 = 0.96). Mean KE was related to end-diastolic volume ( r2 = 0.66 for LV and r2 = 0.74 for RV), end-systolic volume ( r2 = 0.59 and 0.68), and stroke volume ( r2 = 0.55 and 0.60), but not to ejection fraction ( r2 < 0.01, P = not significant for both). Three KE peaks were found in both ventricles, in systole, early diastole, and late diastole. In systole, peak KE in the LV was lower (4.9 ± 0.4 mJ, P = 0.004) compared with the RV (7.5 ± 0.8 mJ). In contrast, KE during early diastole was higher in the LV (6.0 ± 0.6 mJ, P = 0.004) compared with the RV (3.6 ± 0.4 mJ). The late diastolic peaks were smaller than the systolic and early diastolic peaks (1.3 ± 0.2 and 1.2 ± 0.2 mJ). Modeling estimated the proportion of KE to total external work, which comprised ∼0.3% of LV external work and 3% of RV energy at rest and 3 vs. 24% during peak exercise. The higher early diastolic KE in the LV indicates that LV filling is more dependent on ventricular suction compared with the RV. RV early diastolic filling, on the other hand, may be caused to a higher degree of the return of the atrioventricular plane toward the base of the heart. The difference in ventricular geometry with a longer outflow tract in the RV compared with the LV explains the higher systolic KE in the RV.

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