Jean-François Deux

Trials on tissue contractility estimation from cardiac cine MRI using a biomechanical heart model

In this paper we apply specific data assimilation methods in order to estimate regional contractility parameters in a biomechanical heart model, using as measurements real Cine MR images obtained in an animal experiment. We assess the effectiveness of this estimation based on independent knowledge of the controlled infarcted condition, and on late enhancement images. Moreover, we show that the estimated contractility values can improve the model behavior in itself, and that they can serve as an indicator of the local heart function, namely, to assist medical diagnosis for the post-infarct detection of hypokinetic or akinetic regions in the myocardial tissue.

Assessment of calf muscle contraction by diffusion tensor imaging

The goal of this study was to assess the changes of water diffusion during contraction and elongation of calf muscles using diffusion tensor (DT) MRI in normal volunteers. Twenty volunteers (mean age, 29u2009±u20094xa0years) underwent DT MRI examination of the right calf. Echo planar imaging sequence was performed at rest, during dorsal flexion and during plantar flexion. The three eigenvalues (λ1, λ2, and λ3), apparent diffusion coefficient (ADC) and fractional anisotropy (FA) of the diffusion tensor were calculated for medial gastrocnemius (mGM) and tibialis anterior (TA). A fiber tractography was performed on both muscles. Non-parametric Wilcoxon and Mann Whitney tests were used for statistical evaluation. At rest, λ1, λ2 and ADC of mGM were higher than their counterparts of TA (Pu2009u2009<u2009u20090.01). During dorsal flexion, the three eigenvalues and ADC of TA significantly increased (Pu2009<u20090.05) as their counterparts of mGM slightly decreased (P=NS). Opposite variations were detected during plantar flexion of the foot. Visual analysis evidenced a relationship between 3D representations of MRI fibers and physiological state of muscles. Contraction of calf muscles produces changes in DT parameters, which are related to the physiological state of the muscle.

Estimation of tissue contractility from cardiac cine-MRI using a biomechanical heart model

The objective of this paper is to propose and assess an estimation procedure—based on data assimilation principles—well suited to obtain some regional values of key biophysical parameters in a beating heart model, using actual Cine-MR images. The motivation is twofold: (1) to provide an automatic tool for personalizing the characteristics of a cardiac model in order to achieve predictivity in patient-specific modeling and (2) to obtain some useful information for diagnosis purposes in the estimated quantities themselves. In order to assess the global methodology, we specifically devised an animal experiment in which a controlled infarct was produced and data acquired before and after infarction, with an estimation of regional tissue contractility—a key parameter directly affected by the pathology—performed for every measured stage. After performing a preliminary assessment of our proposed methodology using synthetic data, we then demonstrate a full-scale application by first estimating contractility values associated with 6 regions based on the AHA subdivision, before running a more detailed estimation using the actual AHA segments. The estimation results are assessed by comparison with the medical knowledge of the specific infarct, and with late enhancement MR images. We discuss their accuracy at the various subdivision levels, in the light of the inherent modeling limitations and of the intrinsic information contents featured in the data.

Intravoxel incoherent motion (IVIM) MR imaging of colorectal liver metastases: Are we only looking at tumor necrosis?

To determine if intra‐voxel incoherent motion diffusion‐weighted imaging (IVIM‐DWI) parameters, including free molecular‐based (D) and perfusion‐related (D*, f) diffusion parameters, correlate with the degree of tumor necrosis and viable tumor in colo‐rectal cancer (CRC) metastasis.

Role of natriuretic peptide to predict cardiac abnormalities in patients with hereditary transthyretin amyloidosis.

Abstract Background: Familial amyloid polyneuropathy (FAP) mainly targets the peripheral nervous system and heart. Early noninvasive detection of cardiac impairment is critical for therapeutic management. Aim: To assess if amino-terminal pro-brain natriuretic peptide (NT-proBNP) or troponin T (cTnT) can predict echocardiographic left-ventricle (LV) impairment in FAP. Methods: Thirty-six asymptomatic carriers and patients with FAP had echocardiographic measurement of left-ventricular (LV) systolic function, hypertrophy (LVH) and estimation of filling pressure (FP). Results: Overall, median age, NT-proBNP, and LV ejection fraction were, respectively, 59 years (41–74), 323u2009pg/ml (58–1960), and 60% (51–66). Twelve patients had increased cTnT. Prevalence of ATTR gene mutations was 53% for Val30Met. Four individuals were asymptomatic, 6 patients had isolated neurological clinical signs, and 26 had echo-LV abnormalities. The ROC curve identified NT-proBNP patients with echo-LV abnormalities (area: 0.92; (0.83–0.99), pu2009=u20090.001) at a threshold >82u2009pg/ml with a sensitivity of 92%, and a specificity of 90%. Increased in NT-proBNP occurred in patients with SD and/or LVH with or without increase in FP. Elevated cTnT (>0.01ng/ml) was only observed in patients with LVH and systolic dysfunction, with or without FP. Conclusion: In FAP, NT-proBNP was associated with cardiac impairment suggesting that NT-proBNP could be used in carriers or in FAP patients with only neurologic symptoms for identifying the appropriate time to start cardiac echocardiographic assessment and follow-up. cTnT identified patients with severe cardiac disease.

Use of Model-Based Iterative Reconstruction (MBIR) in reduced-dose CT for routine follow-up of patients with malignant lymphoma: dose savings, image quality and phantom study

ObjectivesTo evaluate both in vivo and in phantom studies, dose reduction, and image quality of body CT reconstructed with model-based iterative reconstruction (MBIR), performed during patient follow-ups for lymphoma.MethodsThis study included 40 patients (mean age 49xa0years) with lymphoma. All underwent reduced-dose CT during follow-up, reconstructed using MBIR or 50xa0% advanced statistical iterative reconstruction (ASIR). All had previously undergone a standard dose CT with filtered back projection (FBP) reconstruction. The volume CT dose index (CTDIvol), the density measures in liver, spleen, fat, air, and muscle, and the image quality (noise and signal to noise ratio, SNR) (ANOVA) observed using standard or reduced-dose CT were compared both in patients and a phantom study (Catphan 600) (Kruskal Wallis).ResultsThe CTDIvol was decreased on reduced-dose body CT (4.06xa0mGy vs. 15.64xa0mGy pu2009<u20090.0001). SNR was higher in reduced-dose CT reconstructed with MBIR than in 50xa0% ASIR or than standard dose CT with FBP (patients, pu2009≤u20090.01; phantoms, pu2009=u20090.003). Low contrast detectability and spatial resolution in phantoms were not altered on MBIR-reconstructed CT (pu2009≥u20090.11).ConclusionReduced-dose CT with MBIR reconstruction can decrease radiation dose delivered to patients with lymphoma, while keeping an image quality similar to that obtained on standard-dose CT.Key Points• In lymphoma patients, CT dose reduction is a major concern.• Reduced-dose body CT provides a fourfold radiation dose reduction.• Optimized CT reconstruction techniques (MBIR) can maintain image quality.

Lung imaging during acute chest syndrome in sickle cell disease: computed tomography patterns and diagnostic accuracy of bedside chest radiograph

Introduction The lung computed tomography (CT) features of acute chest syndrome (ACS) in sickle cell disease patients is not well described, and the diagnostic performance of bedside chest radiograph (CR) has not been tested. Our objectives were to describe CT features of ACS and evaluate the reproducibility and diagnostic performance of bedside CR. Methods We screened 127 consecutive patients during 166 ACS episodes and 145 CT scans (in 118 consecutive patients) were included in the study. Results Among the 145 CT scans, 139 (96%) exhibited a new pulmonary opacity and 84 (58%) exhibited at least one complete lung segment consolidation. Consolidations were predominant as compared with ground-glass opacities and atelectasis. Lung parenchyma was increasingly consolidated from apex to base; the right and left inferior lobes were almost always involved in patients with a new complete lung segment consolidation on CT scan (98% and 95% of cases, respectively). Patients with a new complete lung segment consolidation on CT scan had a more severe presentation and course as compared with others. The sensitivity of bedside CR for the diagnosis of ACS using CT as a reference was good (>85%), whereas the specificity was weak (<60%). Conclusions ACS more frequently presented on CT as a consolidation pattern, predominating in lung bases. The reproducibility and diagnostic capacity of bedside CR were far from perfect. These findings may help improve the bedside imaging diagnosis of ACS.

Ruptured visceral artery aneurysms

Visceral artery aneurysms are rare but their estimated mortality due to rupture ranges between 25 and 70%. Treatment of visceral artery aneurysm rupture is usually managed by interventional radiology. Specific embolization techniques depend on the location, affected organ, locoregional arterial anatomy, and interventional radiologist skill. The success rate following treatment by interventional radiology is greater than 90%. The main complication is recanalization of the aneurysm, showing the importance of post-therapeutic monitoring, which should preferably be performed using MR imaging.

Liver magnetic resonance diffusion weighted imaging: 2011 update.

Diffusion-Weighted-Imaging (DWI) assesses proton motion on a cellular scale. Owing to recent instrumentation developments, diffusion sequences are now routinely used for liver imaging. This review will go through the physical principles that underlie this technique, and then highlight up-to-date liver applications including quantification of liver fibrosis, focal lesions detection and characterization, and therapy response monitoring.

Intravascular Papillary Endothelial Hyperplasia of the Jejunum An Unusual Cause of Melena

Intravascular papillary endothelial hyperplasia is considered to be an unusual form of thrombus organization that is marked by an excessive papillary endothelial proliferation. This lesion has the propensity to occur in the skin and the subcutis. Occurrence in the gastrointestinal tract is very rare. The authors report an exceptional case of a 20-year-old young woman with intravascular papillary endothelial hyperplasia in the jejunum. The patient was referred to the hospital with a 1-week history of melena. The lesion did not recur after surgery. Histopathological examination revealed a papillary endothelial hyperplasia with an underlying arteriovenous malformation.