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Background: Energy consumption awareness is a known concern, and radiology departments have energy-intensive consuming machines. The means of energy consumption management in MRI scanners have yet to be evaluated., Purpose: To measure the MRI energy consumption and to evaluate the means to reduce it., Materials and Methods: Data was retrieved for two MRI scanners through the hospital's automated energy consumption measurement software. After correlation with picture archiving and communication system (PACS) files, they were segmented by machine and mode (as follows: stand-by, idle and active) and analyzed. Active mode data for a specific brain MRI protocol have been isolated, and equivalent low energy consuming protocol was made. Both were performed on phantom and compared. Same protocol was performed on a phantom using 3.0T 16 and 32 head channels coils. Multiples sequences were acquired on phantom to evaluate power consumption., Results: Stand-by mode accounted for 60 % of machine time and 40 % of energy consumption, active mode accounted for 20 % machine time and 40 % energy consumption, idle mode for 20 % imachine time and 20 % consumption. DWI and TOF sequences were the most consuming in our brain-MRI protocol. The low energy consuming protocol allowed a saving of approximately 10 % of energy consumption, which amounted for 0.20€ for each examination. This difference was mainly due to an energy consumption reduction of the DWI sequence. There were no difference in consumption between a 3.0T 16 and 32 channels head coils. Sequence's active power and duration (especially considering slice thickness) have to be taken into account when trying to optimize energy consumption., Conclusion: There are two key factors to consider when trying to reduce MRI scan energy consumption. Stand-by mode energy consumption has to be taken into account when choosing an MRI scan, as it can't be changed further on. Active mode energy consumption is dependent of the MRI protocols used, and can be reduced with sequences adaptation, which must take into account sequence's active power and duration, on top of image quality., Competing Interests: Declaration of Competing Interest None., (Copyright © 2023 Elsevier Masson SAS. All rights reserved.)

Gadolinium-based contrast agents (GBCAs) are used in up to 35% of magnetic resonance imaging (MRI) examinations and are associated with an excellent safety profile. Nevertheless, two main issues have arisen in the last two decades: the risk of nephrogenic systemic fibrosis and the risk of gadolinium deposition and retention. As a first step, this article reviews the different categories of GBCAs available in neuroradiology, their issues, and provides updates regarding the use of these agents in routine daily practice. Recent advances in MRI technology, as well as the development of new MRI sequences, have made GBCA injection avoidable in many indications, especially in patients with chronic diseases when iterative MRIs are required and when essential diagnostic information can be obtained without contrast enhancement. These recent advances also lead to changes in recommended MRI protocols. Thus, in a second step, this review focuses on consensus concerning brain MRI protocols in 10 common situations (acute ischemic stroke, intracerebral hemorrhage, cerebral venous thrombosis, multiple sclerosis, chronic headache, intracranial infection, intra- and extra-axial brain tumors, vestibular schwannoma and pituitary adenoma). The latter allowing the standardization of practices in neuroradiology. Recommendations were also made concerning the use of GBCAs in neuroradiology, based on evidence in the literature and/or by consensus between the different coauthors., (Copyright © 2020 Elsevier Masson SAS. All rights reserved.)

Background and Purpose: Assess the evolution of gadolinium consumption and magnetic resonance imaging (MRI) scanners in France and Western Brittany (France) and compare regional practices between public and private hospitals for each organ specialty., Material and Methods: We collected data from national and universal health registries, and Western Brittany's health care structures, between 2011 and 2018, about the number of MR imaging exams and machines, the number of delivered GBCAs (gadolinium-based contrast agents), prescriptions and administration protocols., Results: Over the last eight years, we observed an increase in the number of MRI machines implemented in France (62%), correlated with the increase of annual gadolinium consumption (amount of delivered GBCAs in kg, 64%), without modification of the annual quantity of gadolinium used per machine (2.7kg in 2018). In Western Brittany, gadolinium impact is assigned to neuroimaging exams (50% CI95% [45;56] of all the contrast-enhanced exams), followed by thorax and abdomen exams (23% CI95% [18;28]). The ratio of injected exams to all exams is greater in public than in private hospitals (respectively 48% CI95% [46;49] versus 29% CI95% [26;30])., Conclusion: Gadolinium consumption is increasing, correlated with the increase in the number of examinations carried out. Regionally, the main impact comes from neuroimaging exams. No change in practices has been observed in recent years despite some warnings about gadolinium deposits and environmental consequences., (Copyright © 2020 Elsevier Masson SAS. All rights reserved.)

Spatio-temporal evolution of joint space width (JSW) during motion is of great importance to help with making early treatment plans for degenerative joint diseases like osteoarthritis (OA). These diseases can affect people of all ages leading to an acceleration of joint degeneration and to limitations in the activities of daily living. However, only a few studies have attempted to quantify the JSW from moving joints. In this paper, we present a generic pipeline to accurately determine the changes of the JSW during the joint motion cycle. The key idea is to combine spatial information of static MRI with temporal information of low-resolution (LR) dynamic MRI sequences via an intensity-based registration framework, leading to a high-resolution (HR) temporal reconstruction of the joint. This allows the temporal JSW to be measured in the HR domain using an Eulerian approach for solving partial differential equations (PDEs) inside a deforming inter-bone area where the HR reconstructed bone segmentations are considered as temporal Dirichlet boundaries. The proposed approach has been applied and evaluated on in vivo MRI data of five healthy children to non-invasively quantify the spatio-temporal evolution of the JSW of the ankle (tibiotalar joint) during the entire dorsi-plantar flexion motion cycle. Promising results were obtained, showing that this pipeline can be useful to perform large-scale studies containing subjects with OA for different joints like ankle and knee.

Dynamic MRI has made it possible to non-invasively capture the moving human joints in vivo. Real-time Fast Field Echo (FFE) sequences have the potential to reduce the effect of motion artifacts by acquiring the image data within a few milliseconds. However, the short acquisition times affect the temporal resolution of the acquired sequences. In this paper, we propose a post-processing technique to reconstruct the missing frames of the sequence given the reduced amount of acquired data, which leads to recover the entire joint trajectory outside the MR scanner. To do this, we generalize the Log-Euclidean polyrigid registration framework to deal with dynamic three-dimensional articulated structures by adding the time as fourth dimension : we first estimate the rigid motion of each bone from the acquired data using linear intensity-based registration. Then, we fuse these local transformations to compute the non-linear joint deformations between successive images using a spatio-temporal log-euclidean polyrigid framework. The idea is to reconstruct the missing time frames by interpolating the realistic joint deformation fields in the domain of matrix logarithms assuming the motion to be consistent over a short period of time. The algorithm has been applied and validated using dynamic data from five children performing passive ankle dorsi-plantar flexion.

Introduction: Previous studies have demonstrated the feasibility to explore moisturization with quantification imaging based on T2 mapping. The aim of this study was to describe and validate the first robust automated method to segment the first layers of the skin., Materials and Methods: Data were picked from a previous study that included 35 healthy subjects who underwent a 3T MRI (multi spin echo calculation T2-weighted sequence) with a microscopic coil on the left heel before and one hour after moisturization. The automatic algorithm was composed of the T2 map generation, a Canny filter, a selection of boundaries, and a local regression to delimitate stratum corneum, epidermis, and dermis. An automated affine registration was applied between the exams before and after moisturization., Results: The failure rate of the algorithm was below 5%. Mean computation time was 139.12s. There was a significant and strong correlation between the automatic measurements and the manual ones for the T2 values (ρ: 0.905, P < 0.001) and for the thickness measurements (ρ: 0.8663; P < 0.001). For registration, mean of the Dice index was 0.64 [0.47; 0.80] and of the Hausdorff distance was 0.29 mm 95% CI: [0.28; 0.30]., Conclusion: The proposed automatic method to study the first skin layers in 3T MRI using micro-coils was robust and described T2 values and thickness measurements with a strong correlation to manual measurements. The use of an automated affine registration could also permit the generation of a mapping for a visual assessment of moisturization., (© 2019 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

In this paper, we propose a method for non-invasively measuring three-dimensional in vivo kinematics of the ankle joint from a dynamic MRI acquisition of a single range-of-motion cycle. The proposed approach relies on an intensity-based registration method to estimate motion from multi-plane dynamic MRI data. Our approach recovers not only the movement of the skeleton, but also the possibly non-rigid temporal deformation of the joint. First, the rigid motion of each ankle bone is estimated. Second, a four-dimensional (3D+time) high-resolution dynamic MRI sequence is estimated through the use of the log-euclidean framework for the computation of temporal dense deformation fields. This approach has been then applied and evaluated on in vivo dynamic MRI data acquired for a pilot study on six healthy pediatric cohort in order to establish in vivo normative joint biomechanics. Results demonstrate the robustness of the proposed pipeline and very promising high resolution visualization of the ankle joint., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Aims: The aim of this study was to report the metrological qualities of techniques currently used to quantify skeletal muscle volume and 3D shape in healthy and pathological muscles., Methods: A systematic review was conducted (Prospero CRD42018082708). PubMed, Web of Science, Cochrane and Scopus databases were searched using relevant keywords and inclusion/exclusion criteria. The quality of the articles was evaluated using a customized scale., Results: Thirty articles were included, 6 of which included pathological muscles. Most evaluated lower limb muscles. Partially or completely automatic and manual techniques were assessed in 10 and 24 articles, respectively. Manual slice-by-slice segmentation reliability was good-to-excellent (n = 8 articles) and validity against dissection was moderate to good(n = 1). Manual slice-by-slice segmentation was used as a gold-standard method in the other articles. Reduction of the number of manually segmented slices (n = 6) provided good to excellent validity if a sufficient number of appropriate slices was chosen. Segmentation on one slice (n = 11) increased volume errors. The Deformation of a Parametric Specific Object (DPSO) method (n = 5) decreased the number of manually-segmented slices required for any chosen level of error. Other automatic techniques combined with different statistical shape or atlas/images-based methods (n = 4) had good validity. Some particularities were highlighted for specific muscles. Except for manual slice by slice segmentation, reliability has rarely been reported., Conclusions: The results of this systematic review help the choice of appropriate segmentation techniques, according to the purpose of the measurement. In healthy populations, techniques that greatly simplified the process of manual segmentation yielded greater errors in volume and shape estimations. Reduction of the number of manually segmented slices was possible with appropriately chosen segmented slices or with DPSO. Other automatic techniques showed promise, but data were insufficient for their validation. More data on the metrological quality of techniques used in the cases of muscle pathology are required., Competing Interests: The authors have declared that no competing interests exist.

Purpose: To report evidence for the concurrent validity and reliability of dynamic MRI techniques to evaluate in vivo joint and muscle mechanics, and to propose recommendations for their use in the assessment of normal and impaired musculoskeletal function., Materials and Methods: The search was conducted on articles published in Web of science, PubMed, Scopus, Academic search Premier, and Cochrane Library between 1990 and August 2017. Studies that reported the concurrent validity and/or reliability of dynamic MRI techniques for in vivo evaluation of joint or muscle mechanics were included after assessment by two independent reviewers. Selected articles were assessed using an adapted quality assessment tool and a data extraction process. Results for concurrent validity and reliability were categorized as poor, moderate, or excellent., Results: Twenty articles fulfilled the inclusion criteria with a mean quality assessment score of 66% (±10.4%). Concurrent validity and/or reliability of eight dynamic MRI techniques were reported, with the knee being the most evaluated joint (seven studies). Moderate to excellent concurrent validity and reliability were reported for seven out of eight dynamic MRI techniques. Cine phase contrast and real-time MRI appeared to be the most valid and reliable techniques to evaluate joint motion, and spin tag for muscle motion., Conclusion: Dynamic MRI techniques are promising for the in vivo evaluation of musculoskeletal mechanics; however results should be evaluated with caution since validity and reliability have not been determined for all joints and muscles, nor for many pathological conditions.

Background: Magnetic resonance imaging (MRI) is rarely used for the exploration of skin, even if studies have validated both feasibility of skin MRI and its interest for anatomical, physiological, and biochemical study of the skin. The purpose of this study is to explore moisturizing of the different skin layers using 3-T scan., Methods: An MRI of the heel's skin was performed using a 23 mm coil diameter on a 3T scan with a FFE (Fast Field Echo) 3D T1-weighted sequence and a TSE (Turbo Spin Echo) calculation T2-weighted sequence (pixels size of respectively 60 and 70 μm). This study was conducted on 35 healthy volunteers, who were scanned before applying moisturizer topic and 1 h after applying it. Region of interest in the stratum corneum, the epidermis and the dermis were generated on the T2 mapping. The thickness of each layer was measured. The T1 sequence allowed accurate cross-examination repositioning to ensure the comparability of the measurements., Results: Among the 35 cases, two were excluded from the analysis because of movement artifacts. Measurements before and after moisturizer topic application displayed a T2 increase of 48.94% (P < 0.0001) in the stratum corneum and of 5.45% (P < 0.0001) in the epidermis yet without significant difference in the dermis. There was no significant link between the thickness of the stratum corneum and the T2 increase. However, there was a strong correlation between the thickness of the stratum corneum and the thickness of the epidermis (P < 0.001; rhô=0.72)., Conclusion: High-resolution MRI allows fine exploration of anatomical and physiological properties of the skin and can further be used to extend the studies of skin hydration., (© 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Magnetic resonance imaging (MRI) was used to scan the head of a common dolphin (Delphinus delphis) in order to visualize the different adipose tissues involved in echolocation functioning and to precisely delineate their anatomical topology. MRI scans were performed on the head taken from a freshly stranded carcass and repeated after a 2-week freezing time followed by thawing. The main fatty organs of the head, that is the melon, the mandibula bulba, the bursae cantantes, and their different connections with surrounding tissues were identified and labelled. The nasal sacs, other organs of echolocation, were also identified and labelled thanks to different MRI acquisitions. The shape, the location, the type of MRI signal of each organ and of their different connections were successfully analysed on all images, and then, the images of the head fresh or after thawing were compared. No impacts of the freezing/thawing cycle on the fatty tissues of the head were identified. Different parts were distinguished in the melon on the basis of the MRI signal emitted, corresponding most likely to the internal and external melon already identified by other analytical approaches, and linked to differences in lipid composition. MRI is shown here to be a useful tool to study the functional anatomy of the organs responsible for echolocation in odontocetes, with a particularly high level of precision., (© 2016 Blackwell Verlag GmbH.)

As the population ages and indications for MRI increase, it is estimated that 50 to 75% of patients with a cardiac implantable electronic device (CIED) - pacemaker (PM) or implanted cardiac defibrillator (ICD) - will need an MRI during their CIED's lifetime. Three categories of materials are defined: MRI compatible, MRI non-compatible, and MRI conditional. MRI compatible CIEDs without electrodes have been developed, but do not allow battery changes, so that they are exclusively indicated for patients whose life expectancy is less than that of the battery (6-7years). For MRI conditional CIEDs, all manufacturers publish restrictions. These restrictions can relate to the patient (size, position in the MRI, body temperature), the MRI parameters (magnetic field), or the examination in itself (gradients, specific absorption rate, duration, isocenter). The neuroradiologist can expect to be confronted with the issue of MRI in patients with a CIED. The purpose of this review is to provide them with updated information on MRI and CIEDs., (Copyright © 2016 Elsevier Masson SAS. All rights reserved.)

Objectives: There are significant numbers of military and law enforcement bullets containing ferromagnetic materials. This study aimed to assess the magnetic field interactions for a representative sample of military and law enforcement ballistic objects at 1.5 and 3 tesla (T) to create a magnetic resonance imaging (MRI) compatibility database., Methods: Twenty-nine different bullets underwent MRI evaluation. The deflection angle method and a qualitative torque scale were used. The samples were representative of those commonly used in the North Atlantic Treaty Organization (NATO) military forces (e.g., 5.56 mm NATO), law enforcement agencies (e.g., 9 mm Parabellum), and encountered in war injuries and crime-related trauma (e.g., 7.62 mm Kalashnikov)., Results: At all static magnetic field strengths, all non-nickel- and nonsteel-containing bullets exhibited no movement (deflection angle = 0°; torque = 0), whereas eight bullets containing steel core, steel jacket, or nickel jacket exhibited substantial magnetic field interactions over and above what might be regarded as safe in vivo (deflection angle = 90°; torque = 4+)., Conclusion: Military and law enforcement non-nickel- or nonsteel-containing bullets appear to be safe for patients in MRI system at 1.5 and 3 T. On the other hand, nickel- and steel-containing bullets exhibit movements that are considered potentially unsafe for patients in an MRI environment., (Reprint & Copyright © 2016 Association of Military Surgeons of the U.S.)

Background: Hippocampus is selectively susceptible to ischemic damage and it could be, in some conditions, considered as a border zone of brain ischemia., Results: We illustrate this concept with three cases of hippocampal diffusion-weighted imaging (DWI) restrictions secondary to a carotid artery dissection with an ipsilateral fetal posterior cerebral artery (PCA) in two cases and to global brain hypoperfusion consequent to a cardiac arrest in the last case., Conclusion: The hypoperfusion induced by a cardiac arrest or an internal carotid dissection with an incomplete circle of Willis promotes hippocampal ischemia in the territories of the anterior choroidal artery and the longitudinal terminal segments of the hippocampal arteries., (Copyright © 2011 by the American Society of Neuroimaging.)

Background: Only a few studies have used in/opposed phase method for a quantitative evaluation of fat fraction in the spine., Purpose: To compare multivoxel proton MR spectroscopy and chemical-shift gradient-echo MR imaging for bone marrow fat quantification in vertebral compression fractures (VCF)., Material and Methods: Vertebral marrow fat quantification in fifteen patients was measured at 3.0-T. Multi-voxel proton spectroscopy (MRS) and in/opposed-phase MR imaging using a fat map build with a triple-echo gradient-echo sequence was used. All the patients had benign vertebral collapse. Bone marrow fat content was evaluated by both techniques in compressed (acute or chronic) and in non-compressed vertebrae., Results: The percentage of fat fraction measured by the triple-echo sequence was well correlated with those calculated by MRS (r(2) = 0.85; P < 10(-4)). There was a significant decrease of fat fraction in acute VCF versus both chronic VCF (P < 10(-9)) and non-fractured vertebrae (P < 10(-7)). There was no significant difference in fat fraction evaluated by both techniques between non-fractured vertebrae and chronic VCF., Conclusion: We have validated the in/opposed phase method compared with MRS for vertebral bone marrow fat quantification. The fat mapping using a triple-echo gradient-echo sequence allows distinguishing acute and chronic benign VCF.

The purpose of this study was to validate a magnetic resonance imaging (MRI) technique for mapping liver fat, using (1)H magnetic resonance spectroscopy ((1)H-MRS) as the reference standard. In 91 patients with type 2 diabetes, 3.0-T single-voxel point-resolved (1)H-MRS was used to calculate the liver fat fraction (LFF) from the water (4.76 ppm) and methylene (1.33 ppm) peaks, corrected for T1 and T2 decays. LFF (corrected for T1 and T2* decays) was also obtained from the mean signal intensity on a map built from a triple-echo (consecutive in-phase, opposed-phase, and in-phase echo times) breath-hold gradient echo sequence, using basic image calculation functions (arithmetic mean, subtraction, division, multiplication by a numerical factor). Mean LFF was 8.9% (range, 0.9-33.5) by MRI and 8.8% (range, 0-34.1) by (1)H-MRS. Pearson's coefficient was 0.976 (P < 0.0001) and Lin's coefficient was 0.975 (P < 0.0001). Liver segment had no significant influence. With Bland-Altman analysis, 95.6% (87/91) of data points were within the limits of agreement. Given its excellent agreement with (1)H-MRS, our mapping technique can be used for visual and quantitative evaluation of liver fat in everyday practice.

High resolution MR imaging is ideal for pelvic imaging. To achieve good image quality at 3.0 Tesla MR, one may not simply import protocols used at 1.5 Tesla MR. Issues specific to 3.0 Tesla MR imaging must be considered including chemical shift, magnetic susceptibility, dielectric effect, specific absorption rates (SAR), motion artifacts and optimal echo time (TE) and repetition tome (TR) to achieve the desired tissue contrast. High quality pelvic MRI (prostate, rectum, and female pelvis) at 3.0 Tesla is possible. In addition, it offers potential advantages due to its ability to provide excellent vascular imaging and advances with functional imaging (diffusion, spectroscopy). This article discusses the parameters required to achieve quality pelvic imaging at 3.0 Tesla, the specifics of high-field MR imaging, and illustrates achievable clinical results.

Purpose: To validate a triple-echo gradient-echo sequence for measuring the fat content of the liver, by using hydrogen 1((1)H) magnetic resonance (MR) spectroscopy as the reference standard., Materials and Methods: This prospective study was approved by the appropriate ethics committee, and written informed consent was obtained from all patients. In 37 patients with type 2 diabetes (31 men, six women; mean age, 56 years), 3.0-T single-voxel point-resolved (1)H MR spectroscopy of the liver (Couinaud segment VII) was performed to calculate the liver fat fraction from the water (4.7 ppm) and methylene (1.3 ppm) peaks, corrected for T1 and T2 decay. Liver fat fraction was also computed from triple-echo (consecutive in-phase, opposed-phase, and in-phase echo times) breath-hold spoiled gradient-echo sequence (flip angle, 20 degrees), by estimating T2* and relative signal intensity loss between in- and opposed-phase values, corrected for T2* decay. Pearson correlation coefficient, Bland-Altman 95% limit of agreement, and Lin concordance coefficient were calculated., Results: Mean fat fractions calculated from the triple-echo sequence and (1)H MR spectroscopy were 10% (range, 0.7%-35.6%) and 9.7% (range, 0.2%-34.1%), respectively. Mean T2* time was 14.7 msec (range, 5.4-25.4 msec). Pearson correlation coefficient was 0.989 (P < .0001) and Lin concordance coefficient was 0.988 (P < .0001). With the Bland-Altman method, all data points were within the limits of agreement., Conclusion: A breath-hold triple-echo gradient-echo sequence with a low flip angle and correction for T2* decay is accurate for quantifying fat in segment VII of the liver. Given its excellent correlation and concordance with (1)H MR spectroscopy, this triple-echo sequence could replace (1)H MR spectroscopy in longitudinal studies., ((c) RSNA, 2009.)

Our objective was to investigate the influence of hypertension on N-acetylaspartate (NAA) and choline (Cho) ratios in brain tissues in a community-dwelling elderly population. Brain flexibility was also evaluated with regard to the same metabolite ratios. Proton magnetic resonance spectroscopy (MRS) and the Trail Making Test (TMT) were performed in 80 subjects (75.7+/-4 years old) from the Three-City Study. Fifty-eight participants had hypertension. The NAA/creatine (Cr) and Cho/Cr ratios were obtained in the insular cortex, the thalami and the deep periventricular white matter. In addition, the B-A score of the TMT was evaluated. Uni- and multi-variate analyses were performed in order to examine the relationships among these data. In the insula and the thalami of the hypertensive group, NAA/Cr ratios were significantly lower (1.39+/-0.23 and 1.52+/-0.23, respectively; p=0.01) than those in the normotensive control group (1.52+/-0.25 and 1.70+/-0.19, respectively; p<0.0001), whereas no such reduction was observed in the periventricular white matter of older hypertensive brains. Moreover, the NAA or Cho ratios were significantly correlated with the TMT B-A scores at the level of the thalami, insula and periventricular white matter. These statistical results were confirmed by the multivariate analysis. In an elderly population, hypertension leads to a reduction in NAA/Cr ratios in the insula and the thalami, possibly due to a decrease in blood flow through small perforating and cortical arteries. The TMT B-A test appears to be relevant not only for the frontal areas but also for more remote areas such as the thalami, the insula and the deep periventricular white matter.

Background: The objective of our study was to assess the negative predictive value (NPV) of double-contrast MRI (DC-MRI) with SPIO and gadolinium, and to determine the role of DC-MRI in screening for hepatocellular carcinoma (HCC) in cirrhotic patients., Methods: We retrospectively included 160 DC-MRI scans done as second-line investigations in 119 patients with cirrhosis over a 25-month period. Two radiologists independently classified the MRI scans as strongly suggesting HCC (HCC Group), showing benign nodules (benign nodules Group), showing no nodules (no-nodules Group) or indeterminate; they assigned a diagnostic confidence score (DCS) using a 0-10 scale. The reference standard was histology or results of follow-up investigations. Mean follow-up was 16.9 months (12-28 months)., Results: The radiologists disagreed for two scans (kappa = 0.98). Of 112 scans [benign nodules Group (n = 32) and no-nodules Group (n = 80)], 11 were excluded (3 patients lost to follow-up and 8 who died with no known cancer) while a HCC was detected during follow-up in 8 patients, yielding a NPV of 92% (93/101) (95% confidence interval, 85%-97%). The DCS was in the 4-6 range (indicating uncertainty) for only 6 (3.75%) scans., Conclusions: DC-MRI is reliable and reproducible. Its high NPV suggests a role as a second-line investigation after ultrasonography, for HCC screening.

Liver steatosis may evolve into steatohepatitis then cirrhosis with related complications. It may also contribute to hepatocellular failure, sometimes fatal after major hepatectomy, especially in the setting of liver transplantation with living donor. Imaging must allow non-invasive detection and accurate quantification. In and out of phase MR imaging routinely performed in clinical practice is a simple and robust means of achieving these goals. In this article, we will review the histological, pathophysiologic, and clinical features of liver steatosis and the key points of in and out of phase pulse sequences and underlying physical principles. The T2* relaxation, cause of a loss of signal between both echo times must be taken into account. Echo times must be known for image interpretation, and optimized, especially at 3T. Finally, the T1 of lipids and water is different and causes T1 effects that may lead to quantification errors while being advantageous for image interpretation. The combination of these factors allows detection and quantification of liver steatosis in routine clinical practice.

Objective: Nasopharyngeal tonsilloliths are less well known to radiologists than palatine tonsil lithiases. The possibility of routinely available fine slices during CT scans of the head and neck prompted a retrospective study on the causes and radiological signs and patterns of nasopharyngeal tonsilloliths., Material and Methods: A total of 515 CT scans were retrospectively re-examined looking for calcifications of the posterior wall of the nasopharynx. One patient with this type of calcification underwent a cerebral MRI as part of the etiological workup of his faintness, which also provided a study of the nasopharyngeal wall. The size, density, and position of these calcium concretions were analyzed with CT in all cases., Results: In 31 patients (18 men, 13 women), we discovered one or several calcifications in the pharyngeal mucous area, between 2 and 5.5 mm in size, with a median density of 202 HU. In two cases, we observed that these calcifications adhered to an adenoid cyst, whereas in three cases, the patients had both palatine tonsil and nasopharyngeal calcifications. None of the 31 patients had previously had an adenoidectomy. Sagittal CT and MRI images clearly localized all these calcifications before the pharyngobasilar fascia., Discussion: The position of these nasopharyngeal calcifications in front of the pharyngobasilar fascia means that a calcified vestige of the notochord can be ruled out. Moreover, the simultaneous presence of nasopharyngeal tonsil and palatine tonsil calcifications in three patients is an additional argument for considering these calcifications of the posterior wall of the nasopharynx as tonsilloliths, all of which, representing 6% of the CTs in our series, were asymptomatic., Conclusion: The nasopharyngeal tonsilloliths are stones less than 1 cm in size lodged in the pharyngeal tonsils that are frequently detected on CT when there are no clinical symptoms.

Background and Purpose: This retrospective study investigated the dependence of N-acetyl aspartate (NAA) ratios on risk factors for cerebral vasculopathy such as sex, age, hypertension, diabetes mellitus, carotid stenosis, and dyslipidaemia, which may have affected brain vessels and induced metabolic brain abnormalities prior to stroke. We hypothesise that in stroke patients metabolic alterations in the apparently normal contralateral brain are dependent on the presence or not of such risk factors., Methods: Fifty nine patients (31 male, 28 female: 58.8+/-16.1 years old) with cortical middle cerebral artery (MCA) territory infarction were included. Long echo time chemical shift imaging spectroscopy was carried out on a Siemens 1.5 T Magnetom Vision scanner using a multi-voxel PRESS technique. Metabolite ratios (NAA/choline, NAA/creatine, lactate/choline, etc) were studied using uni- and multivariate analyses with respect to common risk factors. The influence of age, stroke lesion size, and time since stroke was studied using a linear regression approach., Results: Age, sex, and hypertension all appeared to individually influence metabolite ratios, although only hypertension was significant after multivariate analysis. In both basal ganglia and periventricular white matter regions in apparently normal contralateral brain, the NAA/choline ratio was significantly lower in hypertensive (1.37+/-0.16 and 1.50+/-0.19, respectively) than in normotensive patients (1.72+/-0.19 and 1.85+/-0.15, respectively)., Conclusions: Regarding MCA infarction, contralateral tissue remote from the lesion behaves abnormally in the presence of hypertension, the NAA ratios in hypertensive patients being significantly lower. These data suggest that hypertension may compromise the use of contralateral tissue data as a reference for comparison with ischaemic tissue.

The purpose of this retrospective MRI work was to evaluate the use of turbo gradient spin echo (TGSE) high resolution imaging for the detection of eighth nerve schwannomas, without injection of gadolinium. The TGSE sequence (slice thickness: 3 mm with 1.5 mm interleaving; matrix: 512) was compared with a reference sequence: T1-weighted spin echo (SE) after gadolinium injection (slice thickness: 3 mm, matrix: 256). Among 380 internal auditory meatus (IAM) explored, 34 abnormalities were detected on T2-weighted TGSE images compared with 19 on contrast-enhanced T1-weighted SE images. This new sequence has a 100% sensitivity, a 96% specificity and a 100% negative predictive value. Using a rigorous protocol for IAM analysis with the TGSE sequence, gadolinium injection may no longer be needed systematically for vestibular schwannoma screening, but might only be necessary when an abnormality or a doubt persists after TGSE. This approach allows about 20% cost reduction for each patient, a savings of 11,433 euros considering only the true negatives observed in this study.

Purpose: The CT and MR imaging findings in 13patients with lumbar intra spinal synovial cysts were retrospectively analysed and the results of facet corticosteroid injection were evaluated., Patients and Methods: Over a 7 year period, 13patients with radicular pain were identified as having lumbar intra spinal synovial cysts. They ranged from 42 to 87 years of age. All patients were evaluated by CT without contrast material and underwent facet arthrography associated with corticosteroid injection and CT arthrography. MR imaging was performed in all patients either before or after percutaneous treatment. CT scans and MR images were reviewed and patient outcome was evaluated at 1and 6month followup., Results: CT scan revealed a cystic structure adjacent to a degenerated facet joint in 9 patients (69% sensitivity). MRI showed more accurately the cyst on T2 weighted and/or axial images. Complete or good relief of radicular pain and functional restrictions were achieved in 9 patients (69%) at 1 month follow up, still to be found in 6patients (46%) at 6months., Conclusion: In patients with radiculopathy and facet degenerative changes, intra spinal synovial cysts must be looked for. Facet corticosteroid injection is a useful alternative to surgical removal.

Summary: Magnetic resonance imaging (MRI) and computed tomography (CT) scans were used to analyse, respectively, the soft tissues and the bones of the heads of four common dolphins and three harbour porpoises. This imaging study was completed by an examination of anatomical sections performed on two odontocete heads (a subadult common dolphin and a subadult harbour porpoise). The three complementary approaches allowed to illustrate anatomical differences in the echolocation systems of the common dolphin and the harbour porpoise. We captured images confirming strong differences of symmetry of the melon and of its connexions to the MLDB (Monkeys Lips/Dorsal Bursae) between the common dolphin and the harbour porpoise. The melon of the common dolphin is asymmetrically directly connected to the right bursae cantantes at its right side, whereas the melon of the harbour porpoise is symmetrical, and separated from the two bursae cantantes by a set of connective tissues. Another striking difference comes from the bursae cantantes themselves, less deeply located in the head of the common dolphin than in the harbour porpoise. [ABSTRACT FROM AUTHOR]