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ABSTRACT: Personalization is a key aspect of biophysical models in order to impact clinical practice. In this paper, we propose a personalization method of electromechanical models of the heart from cine-MR images based on the adjoint method. After estimation of electrophysiological parameters, the cardiac motion is estimated based on a proactive electromechanical model. Then cardiac contractilities on two or three regions are estimated by minimizing the discrepancy between measured and simulation motion. Evaluation of the method on three patients with infarcted or dilated myocardium is provided.
IEEE transactions on bio-medical engineering 06/2011; 59(1):20-4. · 2.15 Impact Factor
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ABSTRACT: Current guidelines advocate cardiac resynchronisation therapy (CRT) in patients with class III/IV New York Heart Association (NYHA) heart failure, depressed left ventricular function and a broad QRS. However, a significant proportion of patients do not derive any benefit from CRT. The aim of this study was to identify clinical, electrocardiographic and echocardiographic predictors of response to CRT.
A retrospective analysis of patients undergoing CRT in our institution was performed. A favourable clinical response to CRT was defined as an improvement in NYHA Heart failure class of ≥ 1 and lack of hospitalisation with heart failure. Comparisons were made between responders and non-responders in terms of baseline characteristics and potential predictors of CRT response (QRS width, presence of left bundle branch block, atrial fibrillation, evidence of mechanical dyssynchrony on echocardiography and LV lead position).
A total of 164 patients had full follow-up data. The mean follow-up was 293 days. Of patients undergoing CRT, 90 (58.9%) had a favourable clinical response to CRT. Predictors of a lack of clinical response to CRT were male gender (p = 0.012) and chronic obstructive pulmonary disease (COPD) (0.008). Pre-implant echocardiographic dyssynchrony assessment appeared not to predict response to CRT (p = 0.87); however, there was a trend towards a positive response in those patients with significant dyssynchrony (p = 0.09) defined as interventricular delay > 40 ms or maximal LV delay of > 80 ms.
Male gender and coexisting COPD were shown to be independent predictors of non-response to CRT in this cohort of patients fulfilling current criteria for CRT.
International Journal of Clinical Practice 03/2011; 65(3):281-8. · 2.41 Impact Factor
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ABSTRACT: Cardiac catheterization procedures are routinely guided by X-ray fluoroscopy but suffer from poor soft-tissue contrast and a lack of depth information. These procedures often employ pre-operative magnetic resonance or computed tomography imaging for treatment planning due to their excellent soft-tissue contrast and 3D imaging capabilities. We developed a 2D-3D image registration method to consolidate the advantages of both modalities by overlaying the 3D images onto the fluoroscopy by using catheters that are placed in vessels of the heart where they remain throughout the procedure. To achieve registration, an automatic global-fit algorithm was developed which minimized the root-mean-square distance error of the catheter to the medial line of its respective vessel. Data were processed for three clinical cases and an accurate registration was validated by visual inspection.
Computers in Cardiology, 2009; 10/2009
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ABSTRACT: Estimating patient-specific electrical tissue parameters is of considerable benefit towards personalisation of cardiac biophysical models. In this paper, an adaptive inverse parameter estimation algorithm is proposed to estimate the myocardial apparent conductivity from endocardial electrical potential measurements. The forward electrophysiology problem is posed as an Eikonal model and is solved using an anisotropic fast marching method. The conductivity estimation algorithm is validated on patient data obtained using hybrid X-ray/magnetic resonance imaging. Future directions towards improving such estimation procedures are also indicated.
Engineering in Medicine and Biology Society, 2009. EMBC 2009. Annual International Conference of the IEEE; 10/2009
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YingLiang Ma,
G.P. Penney,
D. Bos,
P. Frissen,
G. de Fockert,
A. King,
Gang Gao,
Cheng Yao,
J. Totman, M. Ginks,
C. Aldo Rinaldi,
R. Razavi,
K.S. Rhode
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ABSTRACT: We present an initial evaluation of a robotic arm for positioning a 3D echo probe during cardiac catheterization procedures. By tracking the robotic arm, X-ray table and X-ray C-arm, we are able to register the 3D echo images with live 2D X-ray images. In addition, we can also use tracking data from the robotic arm combined with system calibrations to create extended field of view 3D echo images. Both these features can be used for roadmapping to guide cardiac catheterization procedures. We have carried out a validation experiment of our registration method using a cross-wire phantom. Results show our method to be accurate to 3.5 mm. We have successfully demonstrated the creation of the extended field of view data on 2 healthy volunteers and the registration of echo and X-ray data on 1 patient undergoing a pacing study.
Engineering in Medicine and Biology Society, 2009. EMBC 2009. Annual International Conference of the IEEE; 10/2009
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A P King,
R Boubertakh,
K S Rhode,
Y L Ma,
P Chinchapatnam,
G Gao,
T Tangcharoen, M Ginks,
M Cooklin,
J S Gill,
D J Hawkes,
R S Razavi,
T Schaeffter
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ABSTRACT: We describe a system for respiratory motion correction of MRI-derived roadmaps for use in X-ray guided cardiac catheterisation procedures. The technique uses a subject-specific affine motion model that is quickly constructed from a short pre-procedure MRI scan. We test a dynamic MRI sequence that acquires a small number of high resolution slices, rather than a single low resolution volume. Additionally, we use prior knowledge of the nature of cardiac respiratory motion by constraining the model to use only the dominant modes of motion. During the procedure the motion of the diaphragm is tracked in X-ray fluoroscopy images, allowing the roadmap to be updated using the motion model. X-ray image acquisition is cardiac gated. Validation is performed on four volunteer datasets and three patient datasets. The accuracy of the model in 3D was within 5mm in 97.6% of volunteer validations. For the patients, 2D accuracy was improved from 5 to 13mm before applying the model to 2-4mm afterwards. For the dynamic MRI sequence comparison, the highest errors were found when using the low resolution volume sequence with an unconstrained model.
Medical image analysis 02/2009; 13(3):419-31. · 3.09 Impact Factor
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A.P. King,
R. Boubertakh,
K.S. Rhode,
Y.L. Ma,
P. Chinchapatnam,
G. Gao,
T. Tangcharoen, M. Ginks,
M. Cooklin,
J.S. Gill,
D.J. Hawkes,
R.S. Razavi,
T. Schaeffter
[show abstract]
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ABSTRACT: We describe a system for respiratory motion correction of MRI-derived roadmaps for use in X-ray guided cardiac catheterisation procedures. The technique uses a subject-specific affine motion model that is quickly constructed from a short pre-procedure MRI scan. We test a dynamic MRI sequence that acquires a small number of high resolution slices, rather than a single low resolution volume. Additionally, we use prior knowledge of the nature of cardiac respiratory motion by constraining the model to use only the dominant modes of motion. During the procedure the motion of the diaphragm is tracked in X-ray fluoroscopy images, allowing the roadmap to be updated using the motion model. X-ray image acquisition is cardiac gated. Validation is performed on four volunteer datasets and three patient datasets. The accuracy of the model in 3D was within 5 mm in 97.6% of volunteer validations. For the patients, 2D accuracy was improved from 5 to 13 mm before applying the model to 2–4 mm afterwards. For the dynamic MRI sequence comparison, the highest errors were found when using the low resolution volume sequence with an unconstrained model.
Medical Image Analysis.
