Postmortem magnetic resonance imaging of the heart ex situ: development of technical protocols.

Postmortem MRI (PMMR) examinations are seldom performed in legal medicine due to long examination times, unfamiliarity with the technique, and high costs. Furthermore, it is difficult to obtain access to an MRI device used for patients in clinical settings to image an entire human body. An alternative is available: ex situ organ examination. To our knowledge, there is no standardized protocol that includes ex situ organ preparation and scanning parameters for postmortem MRI. Thus, our objective was to develop a standard procedure for ex situ heart PMMR examinations. We also tested the oily contrast agent Angiofil® commonly used for PMCT angiography, for its applicability in MRI. We worked with a 3 Tesla MRI device and 32-channel head coils. Twelve porcine hearts were used to test different materials to find the best way to prepare and place organs in the device and to test scanning parameters. For coronary MR angiography, we tested different mixtures of Angiofil® and different injection materials. In a second step, 17 human hearts were examined to test the procedure and its applicability to human organs. We established two standardized protocols: one for preparation of the heart and another for scanning parameters based on experience in clinical practice. The established protocols enabled a standardized technical procedure with comparable radiological images, allowing for easy radiological reading. The performance of coronary MR angiography enabled detailed coronary assessment and revealed the utility of Angiofil® as a contrast agent for PMMR. Our simple, reproducible method for performing heart examinations ex situ yields high quality images and visualization of the coronary arteries.

Nonenhanced arterial spin labeled carotid MR angiography using three-dimensional radial balanced steady-state free precession imaging.

PURPOSE: To optimize and preliminarily evaluate a three-dimensional (3D) radial balanced steady-state free precession (bSSFP) arterial spin labeled (ASL) sequence for nonenhanced MR angiography (MRA) of the extracranial carotid arteries. MATERIALS AND METHODS: The carotid arteries of 13 healthy subjects and 2 patients were imaged on a 1.5 Tesla MRI system using an undersampled 3D radial bSSFP sequence providing a scan time of ∼4 min and 1 mm(3) isotropic resolution. A hybridized scheme that combined pseudocontinuous and pulsed ASL was used to maximize arterial coverage. The impact of a post label delay period, the sequence repetition time, and radiofrequency (RF) energy configuration of pseudocontinuous labeling on the display of the carotid arteries was assessed with contrast-to-noise ratio (CNR) measurements. Faster, higher undersampled 2 and 1 min scans were tested. RESULTS: Using hybridized ASL MRA and a 3D radial bSSFP trajectory, arterial CNR was maximized with a post label delay of 0.2 s, repetition times ≥ 2.5 s (P < 0.05), and by eliminating RF energy during the pseudocontinuous control phase (P < 0.001). With higher levels of undersampling, the carotid arteries were displayed in ≤ 2 min. CONCLUSION: Nonenhanced MRA using hybridized ASL with a 3D radial bSSFP trajectory can display long lengths of the carotid arteries with 1 mm(3) isotropic resolution. J. Magn. Reson. Imaging 2015;41:1150-1156. © 2014 Wiley Periodicals, Inc.

Fluorine MR Imaging of Inflammation in Atherosclerotic Plaque in Vivo.

PURPOSE: To preliminarily test the hypothesis that fluorine 19 ((19)F) magnetic resonance (MR) imaging enables the noninvasive in vivo identification of plaque inflammation in a mouse model of atherosclerosis, with histologic findings as the reference standard. MATERIALS AND METHODS: The animal studies were approved by the local animal ethics committee. Perfluorocarbon (PFC) emulsions were injected intravenously in a mouse model of atherosclerosis (n = 13), after which (19)F and anatomic MR imaging were performed at the level of the thoracic aorta and its branches at 9.4 T. Four of these animals were imaged repeatedly (at 2-14 days) to determine the optimal detection time. Repeated-measures analysis of variance with a Tukey test was applied to determine if there was a significant change in (19)F signal-to-noise ratio (SNR) of the plaques and liver between the time points. Six animals were injected with a PFC emulsion that also contained a fluorophore. As a control against false-positive results, wild-type mice (n = 3) were injected with a PFC emulsion, and atherosclerotic mice were injected with a saline solution (n = 2). The animals were sacrificed after the last MR imaging examination, after which high-spatial-resolution ex vivo MR imaging and bright-field and immunofluorescent histologic examination were performed. RESULTS: (19)F MR signal was detected in vivo in plaques in the aortic arch and its branches. The SNR was found to significantly increase up to day 6 (P < .001), and the SNR of all mice at this time point was 13.4 ± 3.3. The presence of PFC and plaque in the excised vessels was then confirmed both through ex vivo (19)F MR imaging and histologic examination, while no signal was detected in the control animals. Immunofluorescent histologic findings confirmed the presence of PFC in plaque macrophages. CONCLUSION: (19)F MR imaging allows the noninvasive in vivo detection of inflammation in atherosclerotic plaques in a mouse model of atherosclerosis and opens up new avenues for both the early detection of vulnerable atherosclerosis and the elucidation of inflammation mechanisms in atherosclerosis.

Eosinophilic fasciitis: Typical abnormalities, variants and differential diagnosis of fasciae abnormalities using MR imaging.

Eosinophilic fasciitis is a rare condition. It is generally limited to the distal parts of the arms and legs. MRI is the ideal imaging modality for diagnosing and monitoring this condition. MRI findings typically evidence only fascial involvement but on a less regular basis signal abnormalities may be observed in neighboring muscle tissue and hypodermic fat. Differential diagnosis of eosinophilic fasciitis by MRI requires the exclusion of several other superficial and deep soft tissue disorders.

Diffusion-weighted MR imaging in musculoskeletal diseases: Current concepts.

MR imaging is currently regarded as a pivotal technique for the assessment of a variety of musculoskeletal conditions. Diffusion-weighted MR imaging (DWI) is a relatively recent sequence that provides information on the degree of cellularity of lesions. Apparent diffusion coefficient (ADC) value provides information on the movement of water molecules outside the cells. The literature contains many studies that have evaluated the role of DWI in musculoskeletal diseases. However, to date they yielded conflicting results on the use and the diagnostic capabilities of DWI in the area of musculoskeletal diseases. However, many of them have showed that DWI is a useful technique for the evaluation of the extent of the disease in a subset of musculoskeletal cancers. In terms of tissue characterization, DWI may be an adjunct to the more conventional MR imaging techniques but should be interpreted along with the signal of the lesion as observed on conventional sequences, especially in musculoskeletal cancers. Regarding the monitoring of response to therapy in cancer or inflammatory disease, the use of ADC value may represent a more reliable additional tool but must be compared to the initial ADC value of the lesions along with the knowledge of the actual therapy.

La perception du paysage dans les images viatiques des Alpes

Etudiant les images viatiques des Alpes présentes dans la base de données VIATIMAGES, au tournant des XVIIIe-XIXe siècles, l'article montre que la prépondérance du sens de la vue dans la perception des paysages est une construction historique et anthropologique. En analysant plus précisément ces images, on peut y repérer des personnages identifiés aux habitants des lieux visités par les voyageurs. Au-delà des stéréotypes du "berger des Alpes", ces images nous disent quelque chose sur la perception pluri-sensorielle et sur l'immédiateté de la présence au monde des paysans alpins. Cependant, une équivoque demeure, que les sources viatiques ne permettent pas de lever, car les qualités attribuées aux paysans des Alpes sont celles mêmes dont les élites urbaines voyageantes sont privées. Dans les zones de contact que sont les sites touristiques au début du XIXe siècle, le regardant et le regardé mettent en miroir leurs qualités sans les partager.

Conditioning of multiple-point statistics facies simulations to tomographic images

Geophysical tomography captures the spatial distribution of the underlying geophysical property at a relatively high resolution, but the tomographic images tend to be blurred representations of reality and generally fail to reproduce sharp interfaces. Such models may cause significant bias when taken as a basis for predictive flow and transport modeling and are unsuitable for uncertainty assessment. We present a methodology in which tomograms are used to condition multiple-point statistics (MPS) simulations. A large set of geologically reasonable facies realizations and their corresponding synthetically calculated cross-hole radar tomograms are used as a training image. The training image is scanned with a direct sampling algorithm for patterns in the conditioning tomogram, while accounting for the spatially varying resolution of the tomograms. In a post-processing step, only those conditional simulations that predicted the radar traveltimes within the expected data error levels are accepted. The methodology is demonstrated on a two-facies example featuring channels and an aquifer analog of alluvial sedimentary structures with five facies. For both cases, MPS simulations exhibit the sharp interfaces and the geological patterns found in the training image. Compared to unconditioned MPS simulations, the uncertainty in transport predictions is markedly decreased for simulations conditioned to tomograms. As an improvement to other approaches relying on classical smoothness-constrained geophysical tomography, the proposed method allows for: (1) reproduction of sharp interfaces, (2) incorporation of realistic geological constraints and (3) generation of multiple realizations that enables uncertainty assessment.

An innovative and shared methodology for event reconstruction using images in forensic science

This study presents an innovative methodology for forensic science image analysis for event reconstruction. The methodology is based on experiences from real cases. It provides real added value to technical guidelines such as standard operating procedures (SOPs) and enriches the community of practices at stake in this field. This bottom-up solution outlines the many facets of analysis and the complexity of the decision-making process. Additionally, the methodology provides a backbone for articulating more detailed and technical procedures and SOPs. It emerged from a grounded theory approach; data from individual and collective interviews with eight Swiss and nine European forensic image analysis experts were collected and interpreted in a continuous, circular and reflexive manner. Throughout the process of conducting interviews and panel discussions, similarities and discrepancies were discussed in detail to provide a comprehensive picture of practices and points of view and to ultimately formalise shared know-how. Our contribution sheds light on the complexity of the choices, actions and interactions along the path of data collection and analysis, enhancing both the researchers' and participants' reflexivity.