Jacques Felblinger

Impact of denoising on precision and accuracy of saturation-recovery-based myocardial T1 mapping

To evaluate the impact of a novel postprocessing denoising technique on accuracy and precision in myocardial T1 mapping.

Abbreviated breast magnetic resonance protocol: Value of high-resolution temporal dynamic sequence to improve lesion characterization

PURPOSE To evaluate the added value of ULTRAFAST-MR sequence to an abbreviated FAST protocol in comparison with FULL protocol to distinguish benign from malignant lesions in a population of women, regardless of breast MR imaging indication. MATERIALS AND METHODS From March 10th to September 22th, 2014, we retrospectively included a total of 70 consecutive patients with 106 histologically proven lesions (58 malignant and 48 benign) who underwent breast MR imaging for preoperative breast staging (n=38), high-risk screening (n=7), problem solving (n=18), and nipple discharge (n=4) with 12 time resolved imaging of contrast kinetics (TRICKS) acquisitions during contrast inflow interleaved in a regular high-resolution dynamic MRI protocol (FULL protocol). Two readers scored MR exams as either positive or negative and described significant lesions according to Bi-RADS lexicon with a TRICKS images (ULTRAFAST), an abbreviated protocol (FAST) and all images (FULL protocol). Sensitivity, specificity, positive and negative predictive values, and accuracy were calculated for each protocol and compared with McNemars test. RESULTS For all readers, the combined FAST-ULTRAFAST protocol significantly improved the reading with a specificity of 83.3% and 70.8% in comparison with FAST protocol or FULL protocol, respectively, without change in sensitivity. By adding ULTRAFAST protocol to FAST protocol, readers 1 and 2 were able to correctly change the diagnosis in 22.9% (11/48) and 10.4% (5/48) of benign lesions, without missing any malignancy, respectively. Both interpretation and image acquisition times for combined FAST-ULTRAFAST protocol and FAST protocol were shorter compared to FULL protocol (p<0.001). CONCLUSION Compared to FULL protocol, adding ULTRAFAST to FAST protocol improves specificity, mainly in correctly reclassifying benign masses and reducing interpretation and acquisition time, without decreasing sensitivity.

Joint reconstruction of image and motion in MRI: implicit regularization using an adaptive 3d mesh

Magnetic resonance images are affected by motion artefacts due to breathing and cardiac beating that occur during the acquisition. Methods for joint reconstruction of image and motion have been proposed recently. Such optimization problems are ill-conditioned, therefore regularization methods are required such as motion smoothness constraints using the Tikhonov method. However with Tikhonov methods the solution often relies on a good choice of the regularization parameter micron, especially in large parameter search spaces (e.g., in 3D reconstructions). In this paper, we propose an adaptive, implicit regularization method which results in subject-specific, spatially varying smoothness constraints on the motion model. It is based on the idea of solving for motion only in certain key points that form a mesh. A practical algorithm is proposed for generating this mesh automatically. The proposed method is shown to have a better convergence rate than the Tikhonov method, both in silico and in vivo. The accuracy of the reconstructed image and motion is also improved.

Pretreatment lesional volume impacts clinical outcome and thrombectomy efficacy: Pretreatment Lesion Volume and Stroke Outcome

We aimed to characterize the association between pretreatment lesional volume measured on diffusion‐weighted images and functional outcome, and estimate the impact on thrombectomy efficacy for ischemic stroke with anterior proximal intracranial arterial occlusion.

MRI ‘EXPOSIMETRY’: HOW TO ANALYZE, COMPARE AND REPRESENT WORKER EXPOSURE TO STATIC MAGNETIC FIELD?

Abstract Worker exposure to electromagnetic fields (EMF) is a growing concern of international commissions. A European directive from 2013 (2013/35/EU) recommend to estimate or measure EMF exposure of all exposed workers. Magnetic resonance imaging (MRI) workers are specially concerned by this point because they work all day long in the vicinity of a very strong magnet (generally 1.5 or 3 T), which cannot be turned off. Setting up a magnetic field monitoring device on these workers would therefore be a good way to ensure their security. European directive threshold adequacy could then be verified. But this verification does not ensure a complete analysis of the worker exposure. Such an analysis based on quality control charts and exposure times metrics has been described in this paper. The proposed magnetic field exposure analysis has additionally been tested on a long‐term exposure follow‐up of 18 MRI workers during 2 months.

Isotropic 3D cardiac cine MRI allows efficient sparse segmentation strategies based on 3D surface reconstruction

Segmentation of cardiac cine MRI data is routinely used for the volumetric analysis of cardiac function. Conventionally, 2D contours are drawn on short‐axis (SAX) image stacks with relatively thick slices (typically 8 mm). Here, an acquisition/reconstruction strategy is used for obtaining isotropic 3D cine datasets; reformatted slices are then used to optimize the manual segmentation workflow.

ArchiMed: A Data Management System for Clinical Research in Imaging

Context: There is a great need in clinical research with imaging to collect, to store, to organize and to process large amount of varied data according to legal requirements and research obligations. In practice, many laboratories or clinical research centers working in imaging domain have to manage innumerous images and their associated data without having sufficient IT (Information Technology) skills and resources to develop and to maintain a robust software solution. Since conventional infrastructure and data storage systems for medical image such as “Picture Archiving and Communication System” (PACS) may not be compatible with research needs, we propose a solution: ArchiMed, a complete storage and visualization solution developed for clinical research. Material and methods: ArchiMed is a service oriented server application written in Java EETM which is integrated into local clinical environments (imaging devices, post-processing workstations, others devices...) and allows to safely collect data from other collaborative centers. It ensures all kinds of imaging data storage with a “study centered” approach, quality control and interfacing with mainstream image analysis research tools. Results: With more than 10 millions of archived files for about 4TB stored with 116 studies, ArchiMed, in function for 5 years at CIC-IT of Nancy-France, is used every day by about 60 persons, among whom are engineers, researchers, clinicians and clinical trial project managers.

Microvascular obstruction by delayed contrast-enhanced MRI remains a strong predictor of left ventricular remodeling even after successful reperfusion in acute myocardial infarction.

Background Microvascular obstruction (MVO) after coronary reperfusion for acute myocardial infarction (AMI) implies advanced myocardial damage and is recognized as a negative prognostic value. Delayed contrast-enhanced MRI is the preferred MR imaging technique for evaluation of MVO. In this study, we assessed the influence of MVO on post-infarction left ventricular (LV) remodeling and dysfunction.