The Potential for Quantifying Regional Distributions of Radial and Shear Strain in the Thoracic and Abdominal Aortic Wall Using Spiral Cine DENSE Magnetic Resonance Imaging

2021 ◽  
Vol 143 (6) ◽  
Author(s):  
Patrick A. Jones ◽  
John S. Wilson
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Shear Strain ◽  
Aortic Wall ◽  
Strain Tensor ◽  
Clinical Diagnostics ◽  
Absolute Difference ◽  
Resonance Imaging ◽  
Minimal Impact ◽  
2D Strain

Abstract Aortic displacement encoding with stimulated echoes (DENSE) magnetic resonance imaging (MRI) was recently developed to assess heterogeneities in aortic wall circumferential strain (CS). However, previous studies neglected potential radial and shear strain (RSS) distributions. Herein, we present an improved aortic DENSE MRI postprocessing method to assess the feasibility of quantifying all components of the two-dimensional (2D) strain tensor. 32 previously acquired 2D DENSE scans from three distinct aortic locations were re-analyzed. Contrasting previous studies, displacements of the inner and outer aortic wall layers were processed separately to preserve RSS. Differences in regional strain between the new and old postprocessing methods were evaluated, along with interobserver, intraobserver, and interscan repeatability for all strain components. The new postprocessing method revealed an overall mean absolute difference in regional CS of 0.01 ± 0.01 compared to the prior method, with minimal impact on CS repeatability. Mean absolute magnitudes of regional RSS increased significantly compared to changes in CS (radial 0.04 ± 0.05, p < 0.001; shear 0.04 ± 0.04, p = 0.02). Most repeatability metrics for RSS were significantly worse than for CS. The unique distributions of RSS for each axial location associated well with local periaortic structures and mean aortic displacement. The new postprocessing method captures heterogeneous distributions of nonzero RSS which may provide new information for improving clinical diagnostics and computational modeling of heterogeneous aortic wall mechanics. However, future studies are required to improve the repeatability of RSS and assess the influence of partial volume effects.

scholarly journals Non-invasive diagnostics in fossils - Magnetic Resonance Imaging of pathological belemnites

2005 ◽  
Vol 2 (2) ◽  
pp. 133-140 ◽  
Author(s):  
D. Mietchen ◽  
H. Keupp ◽  
B. Manz ◽  
F. Volke
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Soft Tissue ◽  
Clinical Diagnostics ◽  
Resonance Imaging ◽  
Non Invasive ◽  
Physiological Processes ◽  
Magnetic Resonance Imaging Mri ◽  
Invasive Diagnostics

Abstract. For more than a decade, Magnetic Resonance Imaging (MRI) has been routinely employed in clinical diagnostics because it allows non-invasive studies of anatomical structures and physiological processes in vivo and to differentiate between healthy and pathological states, particularly of soft tissue. Here, we demonstrate that MRI can likewise be applied to fossilized biological samples and help in elucidating paleopathological and paleoecological questions: Five anomalous guards of Jurassic and Cretaceous belemnites are presented along with putative paleopathological diagnoses directly derived from 3D MR images with microscopic resolution. Syn vivo deformities of both the mineralized internal rostrum and the surrounding former soft tissue can be traced back in part to traumatic events of predator-prey-interactions, and partly to parasitism. Besides, evidence is presented that the frequently observed anomalous apical collar might be indicative of an inflammatory disease. These findings highlight the potential of Magnetic Resonance techniques for further paleontological applications.

Radiographic Methods Are as Accurate as Magnetic Resonance Imaging for Graft Sizing Before Lateral Meniscal Transplantation

2020 ◽  
Vol 48 (14) ◽  
pp. 3534-3540
Author(s):  
Luiz Felipe Ambra ◽  
Camila Cohen Kaleka ◽  
Pedro Debieux ◽  
Julio Cesar Almeida ◽  
Nehal Shah ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Lateral Meniscus ◽  
Absolute Difference ◽  
Resonance Imaging ◽  
Radiographic Method ◽  
Meniscal Transplantation ◽  
Meniscal Allograft ◽  
Anatomic Dissection ◽  
Fresh Frozen

Background: Accurate allograft matching is deemed critical for meniscal transplantation; thus, precise measurements are essential to correctly calculate meniscal size. Several methods for meniscal sizing have been described, but there remains a discussion on which is the most accurate for the lateral meniscus. Purpose: To compare the accuracy of radiographic, anthropometric, and magnetic resonance imaging (MRI) methods of determining width and length of the lateral meniscus with actual dimensions after anatomic dissection. Study Design: Controlled laboratory study. Methods: Ten fresh-frozen human cadaveric knees without any evidence of meniscal or ligamentous injury were primarily imaged using radiography and MRI and subsequently underwent dissection to assess the anatomic size of each meniscus. Four methods were used to predict the size of the lateral menisci: anthropometric, radiographic (Pollard and Yoon), and MRI. Absolute differences in length and width between actual and predicted sizes were determined. Results: The anatomic lateral meniscal width and length were 33.01 ± 4.25 mm (mean ± SD; range, 24.84-40.18 mm) and 31.41 ± 5.06 mm (range, 25.2-40.05 mm), respectively. Regarding width, the anthropometric method demonstrated an absolute difference from anatomic measurement significantly greater when compared with the Pollard technique and MRI ( P = .002). Regarding length, the Pollard method presented an absolute difference significantly greater than all other techniques ( P = .003). In terms of the ability to measure width and length, MRI accurately predicted meniscal size within 10% of the anatomic size in 65% of measurements, the Yoon method in 54%, and the Pollard method in 20% ( P = .01). Radiographs tended to overestimate the true size of the lateral meniscus, while the anthropometric technique overestimated width in all specimens. Conclusion: This study demonstrated that MRI and the Yoon radiographic method are comparable in terms of accuracy for graft sizing before lateral meniscal transplantation. While MRI is useful, a contralateral MRI is required, which makes the Yoon radiographic method recommended given the ease and cost advantage. The original Pollard technique and the anthropometric method are not recommended. Clinical Relevance: Over- and undersizing of meniscal transplants has been implicated in graft failure. Therefore, increasing the reliability of preoperative meniscal measurements is deemed important for the success of meniscal allograft transplantation.

scholarly journals Uniform Fe3O4/Gd2O3-DHCA nanocubes for dual-mode magnetic resonance imaging

2020 ◽  
Vol 11 ◽  
pp. 1000-1009
Author(s):  
Miao Qin ◽  
Yueyou Peng ◽  
Mengjie Xu ◽  
Hui Yan ◽  
Yizhu Cheng ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Contrast Agents ◽  
Mri Contrast Agents ◽  
Clinical Diagnostics ◽  
Resonance Imaging ◽  
Dual Mode ◽  
Mri Contrast ◽  
Magnetic Resonance Imaging Mri

The multimodal magnetic resonance imaging (MRI) technique has been extensively studied over the past few years since it offers complementary information that can increase diagnostic accuracy. Simple methods to synthesize contrast agents are necessary for the development of multimodal MRI. Herein, uniformly distributed Fe3O4/Gd2O3 nanocubes for T 1–T 2 dual-mode MRI contrast agents were successfully designed and synthesized. In order to increase hydrophilicity and biocompatibility, the nanocubes were coated with nontoxic 3,4-dihydroxyhydrocinnamic acid (DHCA). The results show that iron (Fe) and gadolinium (Gd) were homogeneously distributed throughout the Fe3O4/Gd2O3-DHCA (FGDA) nanocubes. Relaxation time analysis was performed on the images obtained from the 3.0 T scanner. The results demonstrated that r 1 and r 2 maximum values were 67.57 ± 6.2 and 24.2 ± 1.46 mM−1·s−1, respectively. In vivo T 1- and T 2-weighted images showed that FGDA nanocubes act as a dual-mode contrast agent enhancing MRI quality. Overall, these experimental results suggest that the FGDA nanocubes are interesting tools that can be used to increase MRI quality, enabling accurate clinical diagnostics.

Assessing Patient-Specific Mechanical Properties of Aortic Wall and Peri-Aortic Structures From In Vivo DENSE Magnetic Resonance Imaging Using an Inverse Finite Element Method and Elastic Foundation Boundary Conditions

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
Johane H. Bracamonte ◽  
John S. Wilson ◽  
Joao S. Soares
Keyword(s):  
Magnetic Resonance Imaging ◽  
Finite Element Method ◽  
Finite Element ◽  
Magnetic Resonance ◽  
Aortic Wall ◽  
Patient Specific ◽  
Resonance Imaging ◽  
Displacement Fields ◽  
Inverse Finite Element Method

Abstract The establishment of in vivo, noninvasive patient-specific, and regionally resolved techniques to quantify aortic properties is key to improving clinical risk assessment and scientific understanding of vascular growth and remodeling. A promising and novel technique to reach this goal is an inverse finite element method (FEM) approach that utilizes magnetic resonance imaging (MRI)-derived displacement fields from displacement encoding with stimulated echoes (DENSE). Previous studies using DENSE MRI suggested that the infrarenal abdominal aorta (IAA) deforms heterogeneously during the cardiac cycle. We hypothesize that this heterogeneity is driven in healthy aortas by regional adventitial tethering and interaction with perivascular tissues, which can be modeled with elastic foundation boundary conditions (EFBCs) using a collection of radially oriented springs with varying stiffness with circumferential distribution. Nine healthy IAAs were modeled using previously acquired patient-specific imaging and displacement fields from steady-state free procession (SSFP) and DENSE MRI, followed by assessment of aortic wall properties and heterogeneous EFBC parameters using inverse FEM. In contrast to traction-free boundary condition, prescription of EFBC reduced the nodal displacement error by 60% and reproduced the DENSE-derived heterogeneous strain distribution. Estimated aortic wall properties were in reasonable agreement with previously reported experimental biaxial testing data. The distribution of normalized EFBC stiffness was consistent among all patients and spatially correlated to standard peri-aortic anatomical features, suggesting that EFBC could be generalized for human adults with normal anatomy. This approach is computationally inexpensive, making it ideal for clinical research and future incorporation into cardiovascular fluid–structure analyses.

scholarly journals The Kora Pacemaker is Safe and Effective for Magnetic Resonance Imaging

2015 ◽  
Vol 9 ◽  
pp. CMC.S24976 ◽  
Author(s):  
Arnaud Savouré ◽  
Alexis Mechulan ◽  
Marc Burban ◽  
Audrey Olivier ◽  
Arnaud Lazarus
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Primary Endpoint ◽  
Electrical Performance ◽  
Absolute Difference ◽  
P Value ◽  
Resonance Imaging ◽  
Open Label ◽  
Mri Conditional ◽  
The Impact

Background The impact of magnetic resonance imaging (MRI) on pacemakers is potentially hazardous. We present clinical results from a novel MRI conditional pacing system with the capability to switch automatically to asynchronous mode in the presence of a strong magnetic field. Aims The IKONE ( Assessment of the MRI solution: KORA 100™ and Beflex™ pacing leads system) study is an open-label, prospective, multicenter study aimed at confirming the safety and effectiveness of the system, when used in patients undergoing MRI of anatomical regions excluding the chest. Methods Primary eligibility criteria included patients implanted with the system, with or without a clinically indicated MRI. The primary endpoint was to confirm no significant change in pacing capture thresholds at 1 month after an MRI, with an absolute difference of ≤0.75 V between the pre- and 1-month post-MRI for both atrial and ventricular capture thresholds. Results Out of 33 patients enrolled (mean age: 72.8 ± 11.4 years, 70% male, implant indication or device), 29 patients implanted with the MRI conditional system underwent an MRI 6-8 week postimplant. The study reached its primary endpoint: the mean absolute difference in pacing capture threshold at 1-month post-MRI versus pre-MRI was less than 0.75 V in the atrium (Δ = 0.18 ± 0.16 V, P-value <0.001) and in the ventricle (Δ = 0.18 ± 0.22 V, P-value <0.001). There were no adverse events related to the MRI procedure nor were there reports of patient symptoms or discomfort associated. MR image quality was of diagnostic quality in all patients. Conclusion Lead electrical performance as measured by difference in capture thresholds were not impacted by MRI. This first clinical evaluation of a novel MRI conditional system demonstrates it is safe and effective for use in out-of-chest, 1.5-T MR imaging.

Leaking aortic aneurysm after repair of coarctation of the aorta: the significance of haemoptysis and magnetic resonance imaging

1997 ◽  
Vol 7 (3) ◽  
pp. 340-343
Author(s):  
S. S. S. Lo ◽  
P. J. Kilner ◽  
J. Somerville
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Aortic Aneurysm ◽  
Emergency Surgery ◽  
Signal Intensity ◽  
Aortic Wall ◽  
Coarctation Of The Aorta ◽  
Resonance Imaging ◽  
Serial Magnetic Resonance Imaging

AbstractWe discuss a patient with recoarctation of the aorta who, 4 weeks after reoperation, presented with fresh haemoptysis and was subsequently found at delayed emergency surgery to have a leaking false aortic aneurysm. The case emphasizes the significance of haemoptysis following repair of recoarctation, the difficulty of reoperation due to abnormalities of the aortic wall, and the value of serial magnetic resonance imaging in demonstrating regions of different signal intensity from haemorrhages of varying age around a leaking false aortic aneurysm.

scholarly journals Evaluation of Distensibility and Stiffness of Ascending Aortic Aneurysm using Magnetic Resonance Imaging

2016 ◽  
Vol 55 (204) ◽  
pp. 67-71
Author(s):  
Kaushal Kishore Tiwari ◽  
Stefano Bevilacqua ◽  
Giovanni Aquaro ◽  
Pierluigi Festa ◽  
Lamia Ait-Ali ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Aortic Aneurysm ◽  
Pulse Wave Velocity ◽  
Wave Velocity ◽  
Aortic Wall ◽  
Pulse Wave ◽  
Ascending Aorta ◽  
Resonance Imaging ◽  
Ascending Aortic Aneurysm

Introduction: Magnetic resonance imaging emerging as a new tool for the diagnosis and evaluation of ascending aortic aneurysm. The aim of our study is to evaluate in vivo distensibility and pulse wave velocity of the aortic wall using functional magnetic resonance imaging technique.Methods: We enrolled 25 patients undergoing surgery for ascending aortic aneurysm and or aortic valve replacement for a period of 8 months. Preoperatively, all the patients underwent functional MRI study of the aorta. Aortic wall distensibility and pulse wave velocity of ascending aorta was evaluated. Results: Mean age of the patient was 66 years (66.68 ± 5.62 years) with 60% (15) male patients. More than fifty percentages of patients were smoker (52%), hypertensive (64%) and diabetic (56%). We have observed significant decrease of distensibilty in the patients with aortic diameter above 50 mm (p-0.0002). Furthermore, we have found a significant inverse correlation between aortic distensibility and pulse wave velocity (R= -0.650, R2= 0.42, p-0.0004). Similarly, we have found a significant inverse correlation between ascending aortic diameter and distensibility of the aorta (R= -0.785, R2= 0.61, p-0.00001). Statistically significant positive correlation was observed between aortic diameter and pulse wave velocity (R= 0.865, R2= 0.74, p-0.00001).Conclusions: MRI measurement of aortic diameters, distensibility, and flow wave velocity is an easy, reliable and reproducible technique. Distensibility and pulse wave velocity define the elasticity of the aorta. We have observed that elasticity of aortic wall is decreased in ascending aorta aneurysm patients. Keywords: ascending aorta aneurysm; distensibility; pulse wave velocity; MRI. | PubMed

Elastic Properties of Aortic Wall in Patients With Bicuspid Aortic Valve by Magnetic Resonance Imaging

2011 ◽  
Vol 108 (1) ◽  
pp. 81-87 ◽  
Author(s):  
Giovanni Donato Aquaro ◽  
Lamia Ait-Ali ◽  
Maira Levorato Basso ◽  
Massimo Lombardi ◽  
Alessandro Pingitore ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Aortic Valve ◽  
Elastic Properties ◽  
Bicuspid Aortic Valve ◽  
Aortic Wall ◽  
Resonance Imaging
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