scholarly journals Cardiac Motion Recovery by Coupling an Electromechanical Model and Cine-MRI Data: First Steps

2008 ◽  
Author(s):  
Florence Billet ◽  
Maxime Sermesant ◽  
Herv� Delingette ◽  
Nicholas Ayache
Keyword(s):  
Data Assimilation ◽  
Energy Coupling ◽  
Magnetic Resonance Images ◽  
Tangential Component ◽  
Cardiac Motion ◽  
Cine Mri ◽  
Electromechanical Model ◽  
Aperture Problem ◽  
Motion Recovery ◽  
Cine Mr

We present a framework for cardiac motion recovery using the adjustment of an electromechanical model of the heart to cine Magnetic Resonance Images (MRI). This approach is based on a constrained minimisation of an energy coupling the model and the data. Our method can be seen as a data assimilation of a dynamic system that allows us to weight appropriately the confidence in the model and the confidence in the data. After a short overview of the electromechanical model of the ventricles, we describe the processing of cine MR images and the methodology for motion recovery. Then, we compare this method to the methodology used in data assimilation. Presented results on motion recovery from given cine-MRI are very promising. In particular, we show that our coupling approach allows us to recover some tangential component of the ventricles motion which cannot be obtained from classical geometrical tracking approaches due to the aperture problem.

scholarly journals Estimation of Myocardial Strain and Contraction Phase From Cine MRI Using Variational Data Assimilation

2016 ◽  
Vol 35 (2) ◽  
pp. 442-455 ◽  
Author(s):  
Viateur Tuyisenge ◽  
Laurent Sarry ◽  
Thomas Corpetti ◽  
Elisabeth Innorta-Coupez ◽  
Lemlih Ouchchane ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Myocardial Strain ◽  
Variational Data Assimilation ◽  
Cine Mri ◽  
Contraction Phase

Modeling Tongue Surface Contours From Cine-MRI Images

2001 ◽  
Vol 44 (5) ◽  
pp. 1026-1040 ◽  
Author(s):  
Maureen Stone ◽  
Edward P. Davis ◽  
Andrew S. Douglas ◽  
Moriel Ness Aiver ◽  
Rao Gullapalli ◽  
...  
Keyword(s):  
Magnetic Resonance Images ◽  
Image Sequences ◽  
Cine Mri ◽  
Tongue Movement ◽  
Mr Image ◽  
Plane Shear ◽  
Tongue Surface ◽  
Horizontal Expansion ◽  
Speech Events ◽  
Made In

This study demonstrated that a simple mechanical model of global tongue movement in parallel sagittal planes could be used to quantify tongue motion during speech. The goal was to represent simply the differences in 2D tongue surface shapes and positions during speech movements and in subphonemic speech events such as coarticulation and left-to-right asymmetries. The study used tagged Magnetic Resonance Images to capture motion of the tongue during speech. Measurements were made in three sagittal planes (left, midline, right) during movement from consonants (/k/, /s/) to vowels (/i/, /a/, /u/). MR image-sequences were collected during the C-to-V movement. The image-sequence had seven time-phases (frames), each 56 ms in duration. A global model was used to represent the surface motion. The motions were decomposed into translation, rotation, homogeneous stretch, and in-plane shear. The largest C-to-V shape deformation was from /k/ to/a/. It was composed primarily of vertical compression, horizontal expansion, and downward translation. Coarticulatory effects included a trade-off in which tongue shape accommodation was used to reduce the distance traveled between the C and V. Left-to-right motion asymmetries may have increased rate of motion by reducing the amount of mass to be moved.

scholarly journals Evaluation of the Dynamic Deformable Elastic Template model for the segmentation of the heart in MRI sequences

2009 ◽  
Author(s):  
Christopher Casta ◽  
Patrick Clarysse ◽  
Joël Schaerer ◽  
Jérome Pousin
Keyword(s):  
Left Ventricle ◽  
Cine Mri ◽  
Mr Images ◽  
Temporal Segmentation ◽  
Cine Mr ◽  
Current Implementation ◽  
Segmentation Accuracy ◽  
Mri Sequences ◽  
Spatio Temporal ◽  
Left Ventricle Myocardium

We introduce a bio-inspired dynamic deformable (DET) model based on the equation of dynamics and including temporal smoothness constraints. The behaviour and characteristics of the dynamic DET model is studied in the context of the semi automatic spatio-temporal segmentation of the left ventricle myocardium in cine-MR images. The segmentation accuracy for endo/epicardium contours at end-diastole and end-systole, and as consequence the performance and limits of the current implementation, is evaluated in the context of the MICCAI LV Segmentation Challenge on a database of 15 multi-slice cine-MRI examinations.

scholarly journals Enhanced MRI-guided radiotherapy with gadolinium-based nanoparticles: preclinical evaluation with an MRI-linac

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
H. L. Byrne ◽  
G. Le Duc ◽  
F. Lux ◽  
O. Tillement ◽  
N. M. Holmes ◽  
...  
Keyword(s):  
Mr Imaging ◽  
Radiation Treatment ◽  
Cine Mri ◽  
Clinical Workflow ◽  
Nanoparticle Uptake ◽  
Image Guided Radiotherapy ◽  
Preclinical Evaluation ◽  
Cine Mr ◽  
Mri Guided ◽  
Radiotherapy Treatment

Abstract Background The AGuIX® (NH TherAguix) nanoparticle has been developed to enhance radiotherapy treatment and provide strong MR contrast. These two properties have previously been investigated separately and progressed to clinical trial following a clinical workflow of separate MR imaging followed some time later by radiotherapy treatment. The recent development of MRI-linacs (combined Magnetic Resonance Imaging–linear accelerator systems enabling MRI-guided radiotherapy) opens up a new workflow where MR confirmation of nanoparticle uptake can be carried out at the time of treatment. A preclinical study was carried out to assess the suitability of a gadolinium-containing nanoparticle AGuIX® (NH TherAguix) for nano-enhanced image-guided radiotherapy on an MRI-linac. Methods Treatments were carried out on F344 Fischer rats bearing a 9L glioma brain tumour. Animals received either: (A) no treatment; (B) injection of nanoparticles followed by MRI; (C) radiotherapy with MRI; or (D) injection of nanoparticles followed by radiotherapy with MRI. Pre-clinical irradiations were carried out on the 1.0 T, 6 MV in-line Australian MRI-linac. Imaging used a custom head coil specially designed to minimise interference from the radiotherapy beam. Anaesthetised rats were not restrained during treatment but were monitored with a cine-MRI sequence. Inductively Coupled Plasma Mass Spectrometry (ICP-MS) analysis was used to quantify residual gadolinium in the brain in normal and tumour tissue. Results A preclinical evaluation of nano-enhanced radiation treatment has been carried out on a 1.0 T MRI-linac, establishing a workflow on these novel systems. Extension of life when combining radiotherapy with nanoparticles was not statistically different from that for rats receiving radiotherapy only. However, there was no detrimental effect for animals receiving nanoparticles and radiation treatment in the magnetic field compared with control branches. Cine-MR imaging was sufficient to carry out monitoring of anaesthetised animals during treatment. AGuIX nanoparticles demonstrated good positive contrast on the MRI-linac system allowing confirmation of tumour extent and nanoparticle uptake at the time of treatment. Conclusions Novel nano-enhanced radiotherapy with gadolinium-containing nanoparticles is ideally suited for implementation on an MRI-linac, allowing a workflow with time-of-treatment imaging. Live irradiations using this treatment workflow, carried out for the first time at the Australian MRI-linac, confirm the safety and feasibility of performing MRI-guided radiotherapy with AGuIX® nanoparticles. Follow-up studies are needed to demonstrate on an MRI-linac the radiation enhancement effects previously shown with conventional radiotherapy.

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