Itch processing in the brain.

Itch is a sensation defined as the urge to scratch. The central mechanisms of itch are being increasingly studied. These studies are usually based on experimental itch induction methods, which can be classified into the following categories: histamine-induced, induction by other non-histamine chemicals (e.g. cowhage), physically induced (e.g. electrical) and mentally induced (e.g. audio-visual). Because pain has been more extensively studied, some extrapolations to itch can be proposed and verified by experiments. Recent studies suggest that the itch-processing network in the brain could be disrupted in certain diseases. This disruption could be related to the implication of new regions or the exclusion of already engaged brain regions from itch-processing network in the brain.

Functional and anatomical brain connectivity in psoriasis patients and healthy controls: a pilot brain imaging study after exposure to mentally induced itch.

BACKGROUND: Despite the prevalence of psoriasis, the processing of itch in psoriasis and its impact on the central nervous system (CNS) remain unclear. OBJECTIVE: We studied the influence of psoriasis on the CNS using magnetic resonance imaging techniques (fMRI and DTI, respectively) to investigate whether mentally induced itch can modify the functional connectivity or the white matter microstructure of the brain. METHODS: Fourteen patients with chronic psoriasis and 15 healthy controls were recruited. Itch was mentally induced in subjects by videos showing others scratching themselves. RESULTS: The observation of functional connectivity during the viewing the video revealed an interconnected network of brain regions that are more strongly coupled in psoriasis patients than in healthy controls. This network links the cerebellum, the thalami, the anteroposterior cingulum, the inferior parietal lobules, the middle temporal poles and the parahippocampal, hippocampal, lingual and supramarginal gyri. We also found connections with the right precuneus and both left insula and superior temporal gyrus. The DTI analysis showed that chronic itch affects the microstructure of white matter, including the anterior thalamic radiations, the superior and inferior longitudinal fasciculi, the corticospinal tracts, the cingulum, the external capsules, the inferior frontal-occipital fasciculi and both minor and major forceps. CONCLUSION: Our results indicate that there could exist a network which is more interconnected in psoriasis patients. Among two building blocks of this network, the subnetwork encoding the perception and control of itch sensation is more affected than the subnetwork representing mentalizing and empathy. With an approach consisting of measuring microstructural changes at a local level in the brain, we also contradict the findings obtained with global measures which stated that chronic psoriasis cannot alter the anatomy of the brain. This confirms that itchy pathophysiological conditions have similar effects on functional and structural connectivity as those observed in chronic pain.

4D in vivo quantification of ankle joint space width using dynamic MRI.

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.

Temporal resolution enhancement of dynamic MRI sequences within a motion-based framework.

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.

Comparative anatomical study of sound production and reception systems in the common dolphin (Delphinus delphis) and the harbour porpoise (Phocoena phocoena) heads.

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.

Magnetic Resonance Imaging Study of Adipose Tissues in the Head of a Common Dolphin (Delphinus delphis): Structure Identification and Influence of a Freezing-Thawing Cycle.

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.

Characterization of the Physiological Displacement of the Aortic Arch Using Non-Rigid Registration and MR Imaging.

OBJECTIVES: The aim of this work was to study physiological aortic arch three-dimensional displacement using non-rigid registration methods and magnetic resonance imaging (MRI). MATERIALS AND METHODS: Ten healthy volunteers underwent thoracic MRI. Prospective cardiac gating was performed with a 3D turbo field echo sequence to obtain end-systolic and end-diastolic MR images. The rigid and elastic behavior between these two cardiac phases was detected and compared using either an affine or an elastic registration method. To assess reproducibility, a second MRI acquisition was performed 14 days later. RESULTS: Affine registration between the end-systolic and end-diastolic MR images showed significant global translations of the aortic arch and the supra-aortic vessels in the x, y, and z directions (2.02 ± 1.6, -0.71 ± 1.1, and -1.21 ± 1.4 mm, respectively). Corresponding elastic registration indicated significant local displacement with a vector magnitude of 5.1 ± 0.89 mm for the brachiocephalic artery (BCA), of 4.26 ± 0.83 mm for the left common carotid artery (LCCA), and of 4.8 ± 0.86 mm for the left subclavian artery (LSCA). There was a difference in displacement between the supra-aortic trunks of the order of 2 mm. Vector displacement was not statistically different between the repeated acquisitions. CONCLUSIONS: The present results showed important deformations in the ostia of supra-aortic vessels during the cardiac cycle. It seems that aortic arch motions should be taken into account when designing and manufacturing fenestrated endografts. The elastic registration method provides more precise results, but is more complex and time-consuming than other methods.

Postmortem computed tomography findings in suicide victims.

Suicide is the eighth cause of mortality in France and the leading cause in people aged between 25 and 34 years. The most common methods of suicide are hanging, self-poisoning with medicines and firearms. Postmortem computed tomography (CT) is a useful adjunct to autopsy to confirm suicide and exclude other causes of death. At autopsy, fractures of the hyoid bone or thyroid cartilage, or both, are found in more than 50% of suicidal hangings. Cervical vertebra fractures are rare and only seen in suicide victims jumping from a great height. Three-dimensional reconstructions from CT data are useful to visualize the ligature mark on the neck. In suicides by firearm, postmortem CT shows entry and exit wounds, parenchymal lesions along the bullet path, as well as projectiles in case of penetrating trauma. However, in the chest and abdomen it is more difficult to identify the path of the projectile. Postmortem CT also shows specific features of suicide by drowning or stabbing, but its use is limited in cases of self-poisoning. The use of postmortem CT is also limited by decomposition and change of body position. This article presents the imaging features seen on postmortem CT according to the method of suicide.

In vivo skin moisturizing measurement by high-resolution 3 Tesla magnetic resonance imaging.

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.

[A subacute dementia: Inflammatory cerebral amyloid angiopathy]. / Une démence rapidement progressive: l'angiopathie amyloïde cérébrale subaiguë inflammatoire.

We report a case of inflammatory cerebral amyloid angiopathy (CAA) that led to rapid cognitive decline, seizures, visual hallucinations, hyperproteinorrachia and right hemispheric leukopathy. Brain biopsy gave the diagnosis of CAA. Although no inflammatory infiltrate was found in the biopsy sample, corticosteroids led to a regression of the radiological lesions without significant clinical improvement. CAA is a rare disease, defined by lesions of classical cerebral amyloid angiopathy and perivascular infiltrates in contact with the affected vessels. In cases of rapidly progressive dementia associated with leukopathy, inflammatory amyloid angiopathy should be considered as cognitive disorders may improve after immunosuppressive therapy.

Factors influencing the occurrence of a T2-STIR hypersignal in the lumbosacral adipose tissue.

PURPOSE: The purpose of our study is to determine whether there is a relation between overweight, age, sex, "hospitalised/outpatient" status and a non-inflammatory hypersignal of the subcutaneous lumbosacral adipose tissue in T2 Short-Tau Inversion-Recovery (T2-STIR) MR imaging sequences. PATIENTS AND METHODS: One hundred and six lumbar MRI, including a T2-STIR and T1 Fluid Attenuated Inversion-Recovery (FLAIR) weighted sagittal sequences, were retrospectively taken from the picture archiving and communication system (PACS) of our hospital and then made anonymous and analysed. The presence or absence of a T2-STIR hypersignal within subcutaneous adipose tissue behind the paraspinal muscle aponeurosis was determined. In addition, the weight, thickness of the fat tissue, the administrative status of the patient, the age, sex, time of the examination and, when present, the height of this hypersignal were noted. A uni- and multivariate analysis by logistic regression was carried out in order to examine the relationship between the data gathered. RESULTS: In the examinations selected, 25.5% (n=27) demonstrated a T2-STIR hypersignal in the subcutaneous tissue. We identified the weight (P<0.023), thickness of the fat tissue (P<0.001), the age of the patient (P<0.017) and the "hospitalised" status (P<0.009) as significant variables associated with this T2-STIR hypersignal. The mean height of the hypersignal was 109.5mm. Five of the 27 patients had an injection of gadolinium chelate and no enhancement was found at this level. CONCLUSION: We found a significant link between overweight, age and "hospitalised" status and the non-inflammatory infiltration of lumbar adipose tissue. This phenomenon seems to correspond with an interstitial oedema, related to subcutaneous stasis. This anomaly should not be confused with a local inflammation.

[Rheumatoid arthritis and meningeal nodules]. / Polyarthrite rhumatoïde et nodules méningés.

INTRODUCTION: Rheumatoid nodules are possible extra-articular manifestations of rheumatoid arthritis. These lesions are mainly located in subcutaneous tissues but may also rarely affect deep organs, exceptionally the meninges. CASE REPORT: We report herein a case of meningeal nodules observed in a 52-year-old man with rheumatoid arthritis who underwent brain MRI to explore an acute visual impairment. Subsequent MRIs showed similar new lesions contrasting with total regression of the initially observed lesions. The final control brain MRI performed four years after the onset of the ocular symptoms disclosed total involution of all the extra-axial nodular lesions, a course highly suggestive of meningeal rheumatoid nodules. CONCLUSION: During the follow-up period of this case, the patient was treated with methotrexate at doses too low to cross the blood brain barrier. Consequently, it is most likely that the meningeal lesions developed during the natural course of the disease. Despite the non-specific features of the first imaging findings, the radiological changes observed over time were consistent with the final diagnosis of rheumatoid nodules.

Overestimation of moderate carotid stenosis assessed by both Doppler US and contrast enhanced 3D-MR angiography in the CARMEDAS study.

PURPOSE: To evaluate the agreement and diagnostic accuracy of Contrast enhanced magnetic resonance angiography (CE-MRA), Doppler ultrasound (DUS) and Digital subtraction angiography (DSA) in the assessment of carotid stenosis. METHODS: DUS, CE-MRA and DSA were performed in 56 patients included in the Carotide-angiographie par résonance magnétique-échographie-doppler-angioscanner (CARMEDAS) multicenter study with a carotid stenosis ≥ 50%. Three readers evaluated stenoses on CE-MRA and DSA (NASCET criteria). Velocities criteria were used for stenosis estimation on DUS. RESULTS: CE-MRA had a sensitivity and specificity of 96-98% and 66-83% respectively for carotid stenoses ≥ 50% and a sensitivity and specificity of 94% and 76-84% respectively for carotid stenoses ≥ 70%. The interobserver agreement of CE-MRA was excellent, except for moderate stenoses (50-69%). DUS had a sensitivity and specificity of 88 and 75% respectively for carotid stenoses ≥ 50% and a sensitivity and specificity of 83 and 86% respectively for carotid stenoses ≥ 70%. Combined concordant CE-MRA and DUS had a sensitivity and specificity of 100 and 85-90% respectively for carotid stenoses ≥ 50% and a sensitivity and specificity of 96-100% and 80-87% respectively for carotid stenoses ≥ 70%. The positive predictive value of the association CE-MRA and DUS for carotid stenoses ≥ 70% is calculated between 77 and 82% while the negative predictive value is calculated between 97 and 100%. CE-MRA and DUS have concordant findings in 63-72%, and the overestimations cases were recorded only for carotid stenosis ≤ 69%. CONCLUSION: Combined DUS-CE-MRA is excellent for evaluation of severe stenosis but remains debatable in moderate stenosis (50-69%) due to the risk of overestimations.

[Pelvic MRI at 3.0 Tesla]. / IRM pelvienne à 3T.

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.

Epidemiology of ischemic stroke from atrial fibrillation in Dijon, France, from 1985 to 2006.

BACKGROUND: Atrial fibrillation (AF) is strongly associated with age, and epidemiologic studies are needed to evaluate the impact of both aging of the population and the use of anticoagulant therapy in patients with AF on the incidence of cardioembolic stroke with AF (CE/AF stroke). METHODS: We evaluated trends in incidence rates, risk factors, prestroke therapy, and survival in CE/AF stroke from a prospective population-based registry, from 1985 to 2006. RESULTS: A total of 3,064 ischemic strokes, including 572 (18.7%) CE/AF strokes, were recorded. Over the 22 years, a decrease in the incidence of overall CE/AF stroke was noted (incidence rate ratio 0.9858, 95% confidence interval [CI] 0.9731-0.9986; p = 0.03). We observed a higher prevalence of previous AF, previous myocardial infarction, and patients aged >70 years in CE/AF stroke (p < 0.0001) whereas hypercholesterolemia was more prevalent in other ischemic strokes (p = 0.003). A significant increase in the use of anticoagulants and antiplatelet agents was noted, and was particularly pronounced for CE/AF stroke with previous AF. For CE/AF stroke, survival rates were 72% at 1 month (95% CI 0.68-0.76), 52% at 1 year (95% CI 0.48-0.56), and 43% at 2 years (95% CI 0.39-0.48), and remained lower than those of other ischemic stroke. CONCLUSIONS: The decrease in the incidence of cardioembolic/atrial fibrillation stroke in our study was probably due to a slight increase in the utilization of antithrombotic therapy in patients with atrial fibrillation, but the use of such therapies will have to increase further because of the expected aging of the population in coming years.

Bilateral optic neuropathy revealing Sjögren's syndrome.

INTRODUCTION: The central nervous system involvement has been reported in 20% of cases of primary Sjogrën's syndrome (SS), a chronic autoimmune disease characterized by a disorder of the exocrine glands secondary to progressive lymphocyte infiltration. Classically described neurological manifestations include sensorimotor deficits, aseptic meningitis or meningoencephalitis, multiple sclerosis-like syndromes and myeolopathies. OBSERVATION: We report here the case of a 53-year-old woman who exhibited rapidly progressive visual loss, disclosing bilateral optic neuropathy, as an uncommon initial symptom of primary SS. Examination of CSF revealed associated aseptic meningitis. Because of the lack of efficacy of the first treatment by intravenous corticosteroids, monthly intravenous cyclophosphamide was quickly introduced. After six months, significant visual recovery was observed. CONCLUSION: Optic neuropathies have been rarely reported as the initial symptom revealing primary Sjogrën syndrome, and bilateral simultaneous lesions remain exceptional.