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BackgroundThe weekend effect has been extensively observed for different diseases and countries and recognized as a fact but without obvious causes.ObjectivesIn this paper we first aimed at investigating the existence of a periodicity in the death count due to Covid-19, and second, at opening the discussion concerning the reality of this effect in this particular context.MethodsDaily statistics of deaths due to the Covid-19 pandemic were subjected to a discrete Fourier transform spectral analysis for France and the world, over the periods from March 29 to May 16, 2020 and from January 22 to May 18, 2020 respectively.ResultsIn both cases, a frequency peak of one harmonic corresponding to a period of 7.11 days was observed for France and the world. In France, this weekly frequency corresponds to a decrease in deaths every Sunday, whereas for the world the systematic decrease is shifted on average by 1.5 days and corresponds to Saturday or Friday.ConclusionAt the world scale and for the epidemic period we confirm the existence of a consecutive weekend effect in the context of the Covid-19 pandemic.

Background To provide insight into bone turnover, quantitative measurements of bone remodeling are required. Radionuclide studies are widely used in clinical care, but have been rarely used in the exploration of the bone in preclinical studies. We describe a bone planar scintigraphy method for frequent assessment of bone activity in mice across the growing period. Since repeated venous radiotracer injections are hardly feasible in mice, we investigated the subcutaneous route. Methods Repeated 99mTc-hydroxymethylene diphosphonate (HMDP) tracer bone planar scintigraphy studies of the knee region and µCT to measure femur growth rate were performed in eight mice between week 6 and week 27 of life, i.e., during their growth period. Three independent investigators assessed the regions of interest (ROI). An index was calculated based on the counts in knees ROI (normalized by pixels and seconds), corrected for the activity administered, the decay between administration and imaging, and individual weights. Results A total of 93 scintigraphy studies and 85 µCT were performed. Repeated subcutaneous tracer injections were well tolerated and allowed for adequate radionuclide studies. Mean scintigraphic indexes in the knees ROI decreased from 87.4 ± 2.6 × 10−6 counts s−1 pixel−1 MBq−1 g−1 at week 6 to 15.0 ± 3.3 × 10−6 counts s−1 pixel−1 MBq−1 g−1 at week 27. The time constant of the fitted exponential decay was equal to 23.5 days. As control mean femur length assessed by µCT increased from 12.2 ± 0.8 mm at week 6 to 15.8 ± 0.2 mm at week 22. The time constant of the fitted Gompertz law was equal to 26.7 days. A correlation index of −0.97 was found between femur growth and decrease of bone tracer activity count between week 6 and 24. Conclusion This methodological study demonstrates the potential of repeated bone planar scintigraphy in growing mice, with subcutaneous route for tracer administration, for quantitative assessment of bone remodeling.

Background: The weekend effect has been extensively observed for different diseases and countries and recognized as a fact but without obvious causes. Objectives: In this paper we first aimed at investigating the existence of a periodicity in the death count due to Covid-19, and second, at opening the discussion concerning the reality of this effect in this particular context. Methods: Daily statistics of deaths due to the Covid-19 pandemic were subjected to a discrete Fourier transform spectral analysis for France and the world, over the periods from March 29 to May 16, 2020 and from January 22 to May 18,2020 respectively. Results: In both cases, a frequency peak of one harmonic corresponding to a period of 7·11 days was observed for France and the world. In France, this weekly frequency corresponds to a decrease in deaths every Sunday, whereas for the world the systematic decrease is shifted on average by 1·5 days and corresponds to Saturday or Friday. Conclusion: At the world scale and for the epidemic period we confirm the existence of a consecutive weekend effect in the context of the Covid-19 pandemic. Funding Statement: None. Declaration of Interests: All authors declare no competing interests.

Different environmental conditions under anesthesia may lead to unstable homeostatic conditions in rodents and therefore may alter kinetics. In this study, the impact of different heating conditions on PET imaging quantification was evaluated. Methods: Two groups of 6 adult female BALB/c nude mice with subcutaneously implanted tumors underwent microPET imaging after injection of 18F-labeled tetrafluoroborate or 18F-FDG. Dynamic scans were acquired under optimal and suboptimal heating conditions. Time-activity curves were analyzed to calculate uptake and washout time constants. Results: With 18F-labeled tetrafluoroborate, optimal animal heating led to a stable heart rate during acquisition (515 ± 35 [mean ± SD] beats/min), whereas suboptimal heating led to a lower heart rate and a higher SD (470 ± 84 beats/min). Both uptake and washout time constants were faster (P < 0.01) in animals maintained with optimal heating. Conclusion: Although the difference in heart rates was slight, optimal heating yielded significantly faster uptake and washout kinetics than suboptimal heating in all organs for both tracers.

The present work compares intravenous (IV) and subcutaneous (SC) routes for contrast-enhanced MRI (CE-MRI) in mice. For that purpose, we selected two contrast media used in clinical practice. MRI acquisitions were performed at 1.5 T on five adult mice (Swiss, 41 g +/- 3 g). On each animal, four acquisitions were achieved with IV and SC administration of either Gd-DOTA or MS-325 (1 acquisition per week). For each route, 0.1 mL of NaCl and 0.1 mL of contrast agent were injected. For each acquisition, 200 T1-weighted images were acquired in a 2 h 34 min time lapse. For each route and contrast medium, dynamic contrast enhancement (DCE) curves were obtained. Time-to-peak (TTP), uptake, and washout constant-time values and contrast-to-noise ratio (CNR) were extracted. IV route TTP value was 4.9 min with Gd-DOTA and 5.4 min with MS-325. SC route TTP was 43.3 min with Gd-DOTA and 45.0 min with MS-325. Despite slower uptake constant-time, we show that SC is a potentially valuable alternative to the IV route in mouse preclinical CE-MRI.

International audience; We use high-resolution [Formula: see text] data in multiple experiments to estimate the sources of error during coregistration of images acquired on separate preclinical instruments. In combination with experiments with phantoms, we completed in vivo imaging on mice, aimed at identifying the possible sources of registration errors, caused either by transport of the animal, movement of the animal itself, or methods of coregistration. The same imaging cell was used as a holder for phantoms and animals. For all procedures, rigid coregistration was carried out using a common landmark coregistration system, placed inside the imaging cell. We used the fiducial registration error and the target registration error to analyze the coregistration accuracy. We found that moving an imaging cell between two preclinical devices during a multimodal procedure gives an error of about [Formula: see text] at most. Therefore, it could not be considered a source of coregistration errors. Errors linked to spontaneous movements of the animal increased with time, to nearly 1 mm at most, excepted for body parts that were properly restrained. This work highlights the importance of animal intrinsic movements during a multiacquisition procedure and demonstrates a simple method to identify and quantify the sources of error during coregistration.

Purpose In patients with primary hyperparathyroidism, the preoperative imaging objective is to locate accurately and reliably uniglandular or multiglandular hyperfunctioning parathyroid, to guide surgery, particularly for minimally invasive method. Subtraction planar scintigraphy with dual-isotope (I/Tc-MIBI) is an efficient examination to specify abnormal parathyroid location, but without accurate anatomic reference. This lack should be avoided by a hybrid SPECT/CT image acquisition. Methods We compared planar scans (neck and mediastinum parallel-hole, associated with anterior neck pinhole) to neck and mediastinum SPECT/CT, all with subtraction (I/Tc-MIBI) method, in exact location of abnormal parathyroid in 50 patients with sporadic primary hyperparathyroidism. Surgical and histological findings were used as the standard of comparison. Results Sensitivity is equivalent for the 2 protocols (86% and 75% for SPECT/CT and planar protocol, respectively, P = 0.15), but SPECT/CT was highly specific (specificity 100% and 90% for SPECT/CT and planar protocol, respectively, P = 0.04). In patients with concomitant thyroid disease, subtraction SPECT/CT appeared to be more sensitive than planar protocol (88% and 62% for SPECT/CT and planar protocol, respectively, P = 0.04). Conclusions In preoperative assessment of primary hyperparathyroidism and to guide surgery, we propose to perform first subtraction SPECT/CT and to complete it with neck pinhole, only if tomoscintigraphy is negative.

Objectives: Quantitative and qualitative image quality evaluation of two different dental CBCT scanners.Methods: Two CBCT systems were evaluated in this study: one small field-of-view (FOV) (50-mm diameter) system that also allows two-dimensional (2D) dental panoramic imaging and one large FOV CBCT system (60-180-mm diameter). These devices were all tested with installed acquisition default modes and proprietary reconstruction software, enabling high-resolution bone imaging. Quantitative analyses were carried out to measure spatial resolution, linearity and homogeneity. Small-size phantoms and a human dry skull were used to evaluate intrinsic performances. Visual qualitative analyses of specific anatomical parts were blindly performed by 10 operators.Results: Concerning spatial resolution, small-voxel size protocols provide equivalent results on the two apparatus. In terms of linearity, all systems are highly linear (0.98 < r2 < 0.99) over the range of signal intensities encountered. Our results, coming from either phantoms or the dry skull, demonstrate that the small FOV CBCT suffers from a lack of homogeneity.Conclusions: For limited oral and maxillofacial volume imaging (diameter < 50 mm), the polyvalent small FOV CBCT (2D and three-dimensional imaging) system used in this study could reach performances similar to those of the large FOV CBCT.

Elliptical Fourier descriptor analysis is a method for the morphometric study of curves. It has been used in the two-dimensional plane for closed contours, but rarely for lines in the three-dimensional space. The method consists of an expansion of a contour as a sum of ellipses. In this article, we study three-dimensional contours, i.e. lines embedded in the three-dimensional space. We compute for the first time the relations between the Fourier coefficients and its geometric parameters. We then use these relations for normalization and reorientation of three-dimensional contours. Such an algorithm can be used to perform inter-individual comparisons between contours, regardless of differences in viewpoint or global size. Human and small animal illustrative examples using biomedical X-ray CT imaging data of open bone structures demonstrate the interest and potential of the method for morphological analysis.

The eXplore CT 120 is the latest generation micro-CT from General Electric. It is equipped with a high-power tube and a flat-panel detector. It allows high resolution and high contrast fast CT scanning of small animals. The aim of this study was to compare the performance of the eXplore CT 120 with that of the eXplore Ultra, its predecessor for which the methodology using the vmCT phantom has already been described [1] . The phantom was imaged using typical a rat (fast scan or F) or mouse (in vivo bone scan or H) scanning protocols. With the slanted edge method, a 10% modulation transfer function (MTF) was observed at 4.4 (F) and 3.9–4.4 (H) mm−1 corresponding to 114 μm resolution. A fairly larger MTF was obtained by the coil method with the MTF for the thinnest coil (3.3 mm−1) equal to 0.32 (F) and 0.34 (H). The geometric accuracy was better than 0.3%. There was a highly linear (R2>0.999) relationship between measured and expected CT numbers for both the CT number accuracy and linearity sections of the phantom. A cupping effect was clearly seen on the uniform slices and the uniformity-to-noise ratio ranged from 0.52 (F) to 0.89 (H). The air CT number depended on the amount of polycarbonate surrounding the area where it was measured; a difference as high as approximately 200 HU was observed. This hindered the calibration of this scanner in HU. This is likely due to the absence of corrections for beam hardening and scatter in the reconstruction software. However in view of the high linearity of the system, the implementation of these corrections would allow a good quality calibration of the scanner in HU. In conclusion, the eXplore CT 120 achieved a better spatial resolution than the eXplore Ultra (based on previously reported specifications) and future software developments will include beam hardening and scatter corrections that will make the new generation CT scanner even more promising.

Resume Objectifs Etude retrospective afin de determiner l’apport de la tomographie par emission de positons a la 18 F-dihydroxyphenylalanine couplee a la tomodensitometrie (TEP-TDM a la 18 F-Dopa) dans l’evaluation des patients aux antecedents de carcinome medullaire de la thyroide (CMT), avec suspicion biologique de maladie evolutive et revue de la litterature. Patients et methodes Dix patients, traites chirurgicalement et presentant une elevation de la calcitonine (130 a 9076 ng/L) et/ou de l’ACE (1,2 a 518 ng/mL) serique, ont beneficie d’au moins une TEP-TDM a la 18 F-Dopa. L’examen corps entier a ete realise 45 et 120 minutes apres l’injection intraveineuse d’environ 4 MBq/kg de 18 F-Dopa. Une analyse visuelle et semiquantitative des images ont ete effectuees. Les resultats scintigraphiques ont ete confrontes aux donnees anatomopathologiques, si disponibles, et/ou a un bilan morphologique centre. Resultats La TEP-TDM a la 18 F-Dopa s’est averee positive chez 70 % des patients retrouvant 25 foyers de fixation pathologique. Une confirmation histopathologique de l’atteinte metastatique a ete obtenue chez quatre des sept patients avec TEP a la 18 F-Dopa positive. La TEP-TDM a la 18 F-Dopa est restee negative chez trois patients, comme le reste de leur bilan morphofonctionnel. Les acquisitions tardives n’ameliorent pas la sensibilite de l’examen. Aucune relation n’a ete retrouvee entre les resultats de la TEP a la 18 F-Dopa et les taux seriques de calcitonine et d’ACE. Conclusion A travers notre serie qui decrit des resultats conformes a ceux de la litterature, la TEP-TDM a la 18 F-Dopa montre son potentiel dans l’evaluation des patients avec suspicion biologique de CMT evolutif. Ces resultats demandent, cependant, a etre confirmes par des series plus importantes.

Summary Objective: The aim of our study was to evaluate the diagnostic contribution of 18F-fluoro-deoxyglucose (18F-FDG)-positron emission tomography (PET)/computed tomography (CT) in patients with fever of unknown origin (FUO) or unexplained prolonged inflammatory syndrome (UPIS) in real life. Patients and methods: We performed a retrospective study including 14 patients with FUO or UPIS hospitalised in our institution (Strasbourg University Hospital, France) between January 2005 and July 2006. 18F-FDG-PET/CT was considered helpful when abnormal results allowed an accurate diagnosis. Results: 18F-FDG-PET/CT was helpful in half the patients (7/14) for final diagnosis. A diagnosis was reached in 87.5% of the patients (7/8) with an abnormal 18F-FDG-PET/CT but only in 50% of the patients (3/6) with a normal 18F-FDG-PET/CT. Conventional chest and abdominal CT was performed in 13 patients before ordering 18F-FDG-PET/CT. We considered that 18F-FDG-PET/CT was essential to establish the final diagnosis in only 23% of the patients (3/13) since neither chest nor abdominal CT identified abnormalities consistent with the final diagnosis. However, among the three patients, two were diagnosed with large vessel vasculitis and one patient with local prosthetic infection. Conclusions: Our study supports the potential interest of 18F-FDG-PET/CT in the diagnostic workup of FUO and UPIS as it helped establish a fine diagnosis in half of the cases. However, 18F-FDG-PET/CT appeared to be essential to the final diagnosis in only 23% of the cases. In our opinion, this protocol should be performed as a second level test, especially when conventional CT is normal or is unable to discriminate between active and silent lesions.

Resume Nous decrivons le cas d’une patiente presentant une sarcoidose nasosinusienne prouvee histologiquement et un cancer du sein inconnu au moment des explorations isotopiques par scintigraphie au 67Ga et TEP-TDM au 18F-FDG. De facon atypique, la scintigraphie au 67Ga s’est revelee peu sensible dans la detection de localisations sarcoidosiques evolutives chez cette patiente. En revanche, la TEP-TDM mettait en evidence de nombreuses adenopathies hypermetaboliques sus- et sous-diaphragmatiques, notamment au niveau des deux creux axillaires pour lesquels l’origine granulomateuse a ete histologiquement prouvee. En revanche, lors de la scintigraphie au 67Ga, un foyer d’hyperfixation mammaire droit a ete mis en evidence, s’averant etre un adenocarcinome canalaire infiltrant avec une composante lobulaire pleiomorphe de grade III sans metastases ganglionnaires. Paradoxalement, aucune anomalie de fixation du 18F-FDG n’a ete detectee au niveau de la tumeur mammaire. L’ensemble de ces resultats est discute en fonction de la nature histologique des lesions et des donnees de la litterature.

Ultrasound-based transient elastography (TE) and magnetic resonance elastography (MRE) are increasingly used methods for the clinical evaluation of soft tissue mechanical properties and their alteration under diseased conditions. This study proposes a comparison between magnetic resonance elastography (MRE) and ultrasound-based transient elastography (TE). Both methods were tested on the same soft tissue-mimicking gels in a common frequency range in order to allow for direct quantitative comparison. For the four gels tested, relatively good agreement was found between the shear moduli measured by both methods, with an averaged relative difference of 23%. This study demonstrates that under the assumption of homogeneous media that are significantly more elastic than viscous, quantitative results obtained by both methods are comparable.

International audience; The rationale of this work is to point out the relevance of in vivo MR images of mice obtained using a dedicated low-field system. For this purpose a small 0.1 T water-cooled electro-magnet and solenoidal radio frequency (RF) transmit–receive coils were used. All MR images were acquired in three-dimensional (3D) mode. An isolation cell was designed allowing easy placement of the RF coils and simple delivery of gaseous anesthesia as well as warming of the animal. Images with and without contrast agent were obtained in total acquisition times on the order of half an hour to four hours on normal mice as well as on animals bearing tumors. Typical in plane pixel dimensions range from 200 × 200 to 500 × 500 µm2 with slice thicknesses ranging between 0.65 and 1.50 mm. This work shows that, besides light installation and low cost, dedicated low-field MR systems are suitable for small rodents imaging, opening this technique even to small research units.

Osteoblastoma (OB) and osteoid osteoma (OO) are benign bone-forming tumors frequently involving vertebrae and long bones of the extremities. Because of their similar histopathological features, distinction between OB and OO is mostly based on size criteria. CT and MRI represent the cornerstone of noninvasive diagnostic procedures, as they provide excellent morphologic details and often obviate the need for confirmatory biopsy. Bone scan is a complementary, highly sensitive functional technique particularly useful for detection of vertebral OO. F-18 FDG PET/CT could have potentiality in diagnosis and post therapeutic evaluation of patients with OB and OO. We report MRI and dynamic F-18 FDG PET/CT results obtained before radiofrequency or laser ablation from 3 patients with an OB of the right L5 pedicle, an OB of the left talus and an OO of the right acetabulum. Both patients with OB underwent posttherapeutic evaluation to confirm the effectiveness of percutaneous radiofrequency ablation.

The peritoneal contact surface area (PCSA), which represents the area parameter in the mass transfer area coefficient (MTAC), is a crucial marker in the evaluation of peritoneal dialysis effectiveness. However, the capacity to recruit a larger PCSA has only been rarely demonstrated in vivo and, in most cases, changes in MTAC are interpreted as permeability changes and not as surface area variations. Here, we report the use of micro-computerized tomography (muCT) for the measurement of PCSA changes to various fill volumes. Using this three-dimensional imaging method, PCSA was measured in vivo in 26 healthy Wistar rats receiving intraperitoneally increasing fill volumes of peritoneal dialysis solutions: 5 mL (group 1, n = 8), 10 mL (group 2, n = 8) and 15 mL (group 3, n = 10) per 100 g of body weight. A non-ionic iodinated contrast agent was added to the dialysis solution in order to distinguish the intraperitoneal dialysis solutions from soft tissues. The normalized PCSA/weight ratio (cm(2)/g) increased with fill volume: 1.12 +/- 0.10 cm(2)/g (range 0.98-1.25) in group 1; 1.74 +/- 0.08 cm(2)/g (range 1.64-1.87) in group 2; 2.13 +/- 0.09 cm(2)/g(range 1.90-2.30) in group 3. With this muCT method, PCSA recruited in vivo with a 10 mL/100 g fill volume was in the range 94-107%) of ex vivo total peritoneal surface area (evPSA), as calculated with the Kuzlan's formula. With a 15 mL/100 g fill volume, the in vivo-measured PCSA, the exchange surface area, surpassed the evPSA (range 113-139%).

Resume Etat de la question Le developpement d’une maladie atherothrombotique acceleree constitue la principale cause de morbi-mortalite des patients diabetiques. Le depistage precoce de l’ischemie myocardique silencieuse (IMS) revet chez ces patients, une importance particuliere. Objectifs Evaluer l’interet : (i) du dosage de marqueurs d’activite de la maladie atherothrombotique refletant les processus inflammatoires (fibrinogene, CRP, MCP-1), l’apoptose (microparticules [MP]), l’activation plaquettaire (CD40-L, P-selectine, GP V, MPs plaquettaires) et endotheliale (VCAM-1, vWF, PAI-1, MPs endotheliales), la stimulation neurohormonale et les pressions de remplissage (BNP) ; (ii) de parametres issus de l’echographie cardiaque ou carotidienne dans le depistage de l’ischemie myocardique identifiee par la realisation d’une scintigraphie myocardique de perfusion. Resultats Cinquante-cinq patients diabetiques (62 ± dix ans) et 15 patients non diabetiques (46 ± 14 ans) ont ete inclus. Le diagnostic d’IMS est etabli chez 23 patients diabetiques (42 %). Une elevation du statut inflammatoire et de l’activation/apoptose leucocytaire est retrouvee dans la population diabetique. Dans l’ensemble de la population etudiee, une elevation des MPs porteuses de CD31 et de CD11a est retrouvee chez les patients presentant une ischemie myocardique. Dans la population diabetique aucun des marqueurs d’activite de la maladie atherothrombotique etudies n’est associe a l’IMS. Au contraire, la masse ventriculaire gauche et la surface de l’oreillette gauche sont associees en analyse univariee a l’IMS. En analyse multivariee, seule la surface de l’oreillette gauche (superieure a 18,5 cm 2 ) est un facteur independamment associe a l’existence d’une ischemie myocardique silencieuse (OR 4,14 ; IC [1,7–16,13] ; p = 0,039). Conclusion Aucun des parametres d’activite de la maladie atherothrombotique etudies ne permet d’identifier les patients diabetiques presentant une IMS. En analyse multivariee, seule la dilatation de l’oreillette gauche est associee au developpement d’une ischemie myocardique silencieuse. Ce parametre pourrait s’integrer dans la stratification du risque myocardique des patients diabetiques.

Peritoneal dialysis (PD) uses the dynamic dialysis properties of the peritoneal membrane. The fraction of the anatomic peritoneal surface area (PSA) recruited is of importance for maximizing exchanges and is potentially impacted by parameters such as fill volume. We describe an in vivo assessment of the contact surface area by micro-computed tomography (μCT) using an iodinated contrast medium added to the PD fluid, a contrast agent presumed without surfactant property. In the isotropic volume (reconstructed voxel size 186 μm x 186 μm x 186 μm), the iodinated PD fluid is automatically selected, thanks to its contrast difference with soft tissues, and its surface area is computed. The method was first tested on phantoms showing the ability to select the PD fluid volume and to measure its surface area. In vivo experiments in rat consisted of μCT acquisition of rat abdomen directly after intraperitoneal administration (10 mL/100 g rat body weight) of a dialysis fluid containing 10% by volume iodinated contrast agent. Fluorescein isothiocyanate albumin was used as dilution marker. We found a strong linear relationship ( R2 = 0.98) between recruited PSA (cm2) and rat weight (g) in the range of 235 to 435 g: recruited PSA = (1.61 weight + 40.5) cm2. Applying μCT with a fill volume of 10 mL/100 g rat body weight, the in vivo measured PSA was in the order of magnitude of the ex vivo anatomic PSA as determined by Kuzlan's formula, considered in most instances as the maximal surface area that can be recruited by PD fluid. This new methodology was the first to give an in vivo high-resolution isotropic three-dimensional (3-D) determination of the PSA in contact with dialysate. Its sensitivity allows us to take into account the recruitment of fine 3-D structures of the PSA membrane that were not accessible to previous 2-D-based imaging methodologies. Its in vivo application also integrates the physiological natural tensile stress of tissues.

This overview first summarizes the last decade of continuous developments and improvements in pre-clinical imaging methods that are now essential tools for in vivo evaluation of cardiac morphology and function in living mice, involving nuclear emission of labeled molecules (micro-PET and micro-SPECT) and electromagnetic wave interactions with biological tissues (micro-CT and micro-MRI). In the following, and for better understanding, the basic physical principles and specific technical innovations of the aforementioned imaging methods are reviewed. Specificity, sensitivity, and spatial and temporal resolutions, together with the corresponding advantages and weaknesses of each method are then discussed, and cardiac image-acquisition protocols and illustrative examples are given for each modality. Emerging hybrid cardiac imaging is also presented and illustrated. Then, recent biological insights provided by mouse cardiac imaging are presented. Finally, imaging strategies in mouse cardiac phenotyping involving the aforementioned methods, adding metabolic and molecular information to morphological data, are emphasized and discussed. Curr. Protoc. Mouse Biol. 2:129-144 © 2012 by John Wiley & Sons, Inc.

Magnetic resonance (MR) diffusion imaging provides a valuable tool used for inferring structural anisotropy of brain white matter connectivity from diffusion tensor imaging. Recently, several high angular resolution diffusion models were introduced in order to overcome the inadequacy of the tensor model for describing fibre crossing within a single voxel. Among them, q -ball imaging (QBI), inherited from the q -space method, relies on a spherical Radon transform providing a direct relationship between the diffusion-weighted MR signal and the orientation distribution function (ODF). Experimental validation of these methods in a model system is necessary to determine the accuracy of the methods and to optimize them. A diffusion phantom made up of two textile rayon fibre (comparable in diameter to axons) bundles, crossing at 90°, was designed and dedicated to ex vivo q -ball validation on a clinical scanner. Normalized ODFs were calculated inside regions of interest corresponding to monomodal and bimodal configurations of underlying structures. Three-dimensional renderings of ODFs revealed monomodal shapes for voxels containing single-fibre population and bimodal patterns for voxels located within the crossing area. Principal orientations were estimated from ODFs and were compared with a priori structural fibre directions, validating efficiency of QBI for depicting fibre crossing. In the homogeneous regions, QBI detected the fibre angle with an accuracy of 19° and in the fibre-crossing region with an accuracy of 30°.

Targeted mutagenesis offered new opportunities to investigate the pathophysiology of congestive heart failure and opened the door for the identification of new pharmacological targets. Moreover, recent developments of cardiac functional imaging, with techniques such as echocardiography, single photon emission tomography and magnetic resonance imaging were adapted for the mouse and gave new insights in mouse cardiac physiology, development, pharmacology and phenotyping. This short review focuses on the main models used in this field and addresses some of their technical limitations and physiological considerations.

Our aim was to conduct a quantitative and qualitative evaluation of high-resolution skull-bone imaging for dentistry and otolaryngology using different architectures of recent X-ray computed tomography systems.Three multi-slice computed tomography (MSCT) systems and one Cone-beam computed tomography (CBCT) system were used in this study. All apparatuses were tested with installed acquisition modes and proprietary reconstruction software enabling high-resolution bone imaging. Quantitative analyses were performed with small fields of view with the preclinical vmCT phantom, which permits to measure spatial resolution, geometrical accuracy, linearity and homogeneity. Ten operators performed visual qualitative analyses on the vmCT phantom images, and on dry human skull images.Quantitative analysis showed no significant differences between protocols in terms of linearity and geometric accuracy. All MSCT systems present a better homogeneity than the CBCT. Both quantitative and visual analyses demonstrate that CBCT acquisitions are not better than the collimated helical MSCT mode.Our results demonstrate that current high-resolution MSCT protocols could exceed the performance of a previous generation CBCT system for spatial resolution and image homogeneity.• Quantitative evaluation is a prerequisite for comparison of imaging equipment. • Bone imaging quality could be objectively assessed with a phantom and dry skull. • The current MSCT shows better image quality than a dental CBCT system. • CBCT remains a work-in-progress technology.

The high xenon solubility in blood and tissues makes hyperpolarized 129 Xe a potential MR tracer for tissue perfusion studies. Two biocompatible fluids were studied with a view to be used as delivery media for hyperpolarized xenon injection: the carrier agents were 129 Xe micro-bubbles in Echovist (2–3 μm in diameter), and Intralipid 129 Xe suspension. Xenon chemical shifts and longitudinal relaxation time T 1 were measured at 2.35 T in both fluids. Xenon chemical shift of the dissolved phase in Echovist was 204.1 ± 0.5 ppm from the micro-bubbles gas phase resonance data (0 ppm). Xenon T 1 was 20.0 s in micro-bubbles in Echovist and 19.0 s for the dissolved phase. Xenon chemical shift in Intralipid was 194.6 ± 0.5 ppm. T 1 was 15.2 ± 4.9 s ( n = 5) in Intralipid 20 % and 20.9 ± 2.9 s ( n = 4) in Intralipid 30 %. Using an intra-carotid injection of a small volume (0.15 mL) of hyperpolarized xenon dissolved in Intralipid 30 %, cerebral blood flow was measured in rats (160 ± 30 mL·(100 g) –1 ·min –1 , n = 10). Rat brain xenon images were performed with 2-D projection–reconstruction pulse sequence, enabling regional blood flow measurements.

Resume Propos. – De nouveaux concepts ont ete recemment developpes sur les carences en vitamine B12 : l’existence chez la personne âgee d’un mecanisme frequent de non-dissociation de la vitamine B12 de sa proteine porteuse et la possibilite d’une supplementation par vitamine B12 cristalline per os. L’objectif de ce travail est de confirmer ces concepts sur une serie de patients âges de plus de 75 ans et presentant une anemie par carence en vitamine B12. Methodes. – Il s’agit d’une etude retrospective sur cinq ans. Elle inclut les patients âges de plus de 75 ans presentant une anemie (hemoglobine inferieure a 12 g/dL) par carence en vitamine B12 (B12 inferieure a 160 pg/mL). Resultats. – Vingt observations ont ete analysees. L’âge moyen des patients est de 82,5 ± 6 ans et le sex-ratio F/H est de 1,2. L’hemoglobine moyenne est a 7,9 ± 2,4 g/dL, la vitamine B12 serique a 83 ± 24 pg/mL et l’homocysteinemie a 35 ± 27 μmol/L. Les diagnostics retenus sont ceux de non-dissociation de la vitamine B12 (n = 10), de maladie de Biermer (n = 5), de malabsorption sur insuffisance pancreatique (n = 1) et de carence d’apports (n = 1). Parmi les non-dissociations de la vitamine B12, celles-ci sont liees a une gastrite atrophique et a la presence de Helicobacter pylori (n = 6), a la prise d’antiacides ou de biguanides (n = 3), a une exogenose (n = 2), ou sont idiopathiques (n = 2). Pour les patients avec un suivi (n = 10), l’administration de vitamine B12 par voie intramusculaire (n = 5) ou cristalline per os (n = 5) a permis la correction des anomalies de l’hemogramme. Conclusion. – Chez le sujet âge, la non-dissociation de la vitamine B12 est le principal mecanisme des carences en vitamine B12. Il est souvent lie a une gastrite atrophique. Le traitement par vitamine B12 cristalline per os est efficace et pourrait etre propose.

Because of its high diagnostic sensitivity in detection of unknown primary tumors, F-18 FDG PET/CT was used in the exploration of a 51-year-old woman presenting with multiple lymphadenopathy of the hepatic hilum and several hepatic and splenic hypodensities on radiologic examinations for which malignancy was suspected. Despite the morphofunctional malignant appearance, both histologic examination and PCR analysis revealed Bartonella henselae infection. Moreover, repeat F-18 FDG PET showed disease regression during focused antibiotic therapy.

In-111 DTPA-D-Phe1-octreotide (In-111 pentetreotide) is a widely used radiotracer for somatostatin receptor (SSTR) in- vestigations in neuroendocrine (NE) pathology. Cellular SSTR den- sity is directly related to the degree of NE cellular differentiation. Poorly differentiated cell lines show a surface reduction of SSTRs, which may lead to misinterpreting the In-111 pentetreotide scintig- raphy results as negative. A case of anorectal small-cell undifferen- tiated neuroendocrine carcinoma is reported. This pathologic finding is rare, highly aggressive, and associated with a dramatic prognosis. The patient was investigated with In-111 pentetreotide SPECT and low-dose computed tomography (CT) for anatomic reference. De- spite its low degree of differentiation, the tumor showed high tracer uptake characterized by a positive incremental trend as shown by comparison of the 4-hour and 24-hour SPECT images, suggesting specific receptorial binding of In-111 pentetreotide.

PURPOSE In patients experiencing colorectal carcinoma, exhaustive analysis of indicates extent of hepatic and pulmonary surgery that prolongs survival of patients. PATIENTS AND METHODS To localize metastasis, we compared 2 F-FDG PET-CT imaging protocols, early respiratory gated scan, and delayed scan, to standard PET imaging procedure. SUVmax and lesion-to-healthy tissue ratio were measured in 60 pulmonary and 21 hepatic lesions by each of the 2 imaging protocols. RESULTS In the liver, metastatic lesion-to-healthy tissue ratios significantly increased on delayed scans as compared with early scans (P < 0.001). Better ratios could not be obtained when using respiratory gated scans, whereas more lesions were detected on delayed scans. In the lungs, metastatic lesion- to-healthy tissue ratio increased significantly on delayed scans for largest lesions (P < 0.001). Ratios were not better when exploring smallest metastatic lesions or when using respiratory gated scans. Factors interfering with F-FDG PET-CT sensitivity are discussed, such as respiratory motion and high FDG physiological uptake in healthy liver parenchyma. CONCLUSIONS Our studies indicate that routine acquisitions should use delayed hepatic scans for all patients referred for evaluation, recurrence check, or monitoring of colorectal adenocarcinoma. Delayed pulmonary scans are useful for the largest metastatic lesions and should be used in addition to early scan. In our experience, respiratory gated scans seem to be less convenient because of a low sensitivity in detection, as compared with the delayed technique; in addition, this technique is currently complicated by some technical issues, although these might be overcome with new gated protocols.

Three glomus tumors of the fingers were detected using a dedicated hand and wrist low field (0.1 T) MR imager equipped with solenoidal coils allowing a FOV of 2 cm. Three-dimensional T1-, T*2-, or T2-weighted images were used (8 contiguous slices of 2 mm thickness). Glomus tumors had low or intermediate signal intensity (2 cases) or no signal (1 case) on T1-weighted images. On T*2- or T2-weighted images they had high signal intensity. MRI findings correlate well with surgery and biopsy.

In this study, we used single photon emission computed tomography (SPECT) radiolabelled 99mTc HMPAO to assess cerebral perfusion during maturation in the neonatal period. Results of SPECT examinations in 18 newborn infants, in whom gestational age ranged form 30 to 41 weeks, and who were found to be neurologically normal in retrospect, were reviewed. The developmental changes in cerebral perfusion during the neonatal period shown by SPECT parallel findings of other methods on maturational changes of the central nervous system (neuropathological studies, positron emission tomography scan, magnetic resonance imaging). Cerebral perfusion progresses from the central part of the brain to the cerebellum, sensorimotor and then visual cortex. A close relation seems to exist between cerebral perfusion, metabolism and behavior under normal conditions in the neonatal period.

Collagen is a major component of the extracellular matrix and a determinant of the elastic behavior of the human aorta. To investigate the changes found in aneurysmal degeneration, the authors studied the solid-state hydrogen-1 nuclear magnetic resonance line shape of collagen in aneurysms and normal human aortas. A three-component decomposition of the free induction decay was performed, with collagen characterized by a T2 of about 18 microseconds. The second moment of the collagen line shape was found to be increased in aneurysms (5.3 vs 4.8 G2), while, correspondingly, the T2 of collagen was lower in aneurysms (16.3 vs 17.7 microseconds). This corresponds to a modification of collagen structure and molecular motion. Collagen concentration was lower in nondiseased aortic walls (9.4% vs 7.3%). These results are discussed in reference to the contradictory conclusions in the current literature. The increase in collagen and the modification of its structure and molecular motion are explained by the need to resist an increasing tangential tension due to increased aortic diameter and diminished wall thickness in aneurysms and by intercalation or site binding in the helices or electric dipolar interactions in the less mobile side groups.

Activated inflammatory cells like neutrophils, macrophages, and lymphocytes have increased F-18 FDG uptake, causing significant tracer accumulation in inflammatory and infectious processes. In this report, we have illustrated F-18 FDG PET/CT features related to systemic sarcoidosis, large-vessel arteritis, abdominal tuberculosis, and pleural aspergillosis in 4 selected patients, who underwent scintigraphic evaluation before and after anti-inflammatory or antibiotic treatment. The evolution of radiotracer uptake intensity reflected the efficacy of medical treatment, permitting either a better modulation of drug dosage or a radical modification of therapeutic strategy. Independently from the cost and access to this type of medical imaging, F-18 FDG PET/CT could have a potential role in assessing treatment efficacy in selected non-neoplastic conditions, allowing morphofunctional cartography of residual inflammatory localizations.

Background Operators and patient radiation exposure during interventional cardiology procedures may induce radiation injury and may increase risk of cancer. Objectives To determine the effectiveness of a lead cover placed over the patient abdomen and groins in reducing operator radiation exposure during coronary intervention. Methods Radiation exposure measurements were performed over an 8 weeks period, in patients undergoing diagnostic and/or interventional coronary procedures. Usual protection of the operator was ensured using a lead apron, low leaded flaps, and leaded glass. Each of three procedures was realized using a lead cover placed on the patient abdomen. Operator irradiation was assessed by using 3 electronic dosimeters placed over the apron on the chest and in the back (no 1, 2) on the left arm (no 3). Patient radiation exposure (using the diamentor system), ambiental irradiation (using an electronic dosimeter placed in the room opposite to the Xray tube) and fluoroscopy times were recorded. Results are presented in mean ± SEM and comparisons assessed by student t test. Results Operator exposure was assessed during 189 procedures (136 coronary angiograms and 53 percutaneous coronary interventions) in 71 cases (37%) with the lead cover over the patient (group 1) and in 118 cases (63%) without it (group 2). Fluoroscopy times, dose area products and ambient irradiation were similar with and without the lead cover (4 ± 2 vs 4.1 ± 0.6 min, 55,7 ± 5,8 vs 57,6 ± 4,2 Gy cm2 and 0.7 ± 0.2 vs 0.8 ± 0.1 μSv respectively – p > 0.05). However, operator irradiation was markedly decreased by using the lead cover: from 19.2 ± 3.1 to 4.9 ± 0.9 μSv at the chest level (p=0,001), from 1.8 ± 0.3 to 0.3 ± 0.1 μSv at the back (p=0.002) and from 25.8 ± 4.7 to 10.2 ± 2.2 μSv at the left arm (p=0,019). Conclusions Using a lead cover placed over the patient is highly effective in attenuating operator scatter radiation exposure during coronary procedure. Such additional protection device might be useful either in the perspective of long duration procedure or in routine use.

The desmoplastic small round cell tumor (DSRCT) is an uncommon and highly aggressive cancer. The role of 18F-FDG PET in management of DSRCT is little reported. We report a case of metastasized abdominal DSRCT detected in a 43-year old patient whose diagnostic and therapeutic approaches were influenced by 18F-FDG PET-CT. The patient is still alive ten years after diagnosis. 18F-FDG PET-CT seems to be a useful method for assessing therapeutic efficiency and detecting early recurrences even in rare malignancies such as DSRCT.

The synthesis and functionalisation of zeolite nanoparticles designed for laser-polarized 129Xe NMR experiments in solution are described. These nanoparticles were functionalized by using original synthesis pathways through semicarbazide COCHO chemistry in order to ensure anchoring of a peptide for targeting biological receptors and attachment of PEG chains for in vivo experiments. Results demonstrated that accessibility of the dissolved noble gas to the micropores was maintained after functionalization. γ Scintigraphy with 111In linked to the zeolite particles has been investigated in order to follow the behaviour of the zeolite nanoparticles in mice. These preliminary 111In scintigraphy experiments showed the localization of the nanoparticles after injection in mice and their biodistribution, as a first proof-of-concept towards in vivo129Xe MRI.

To gain more insight into the involvement of inflammatory response and neurohumoral activation in Takotsubo cardiomyopathy (TTC), we investigated C-reactive protein (CRP), leukocytes, plasma catecholamines levels, iodine 123 meta-iodobenzylguanidine (123I-mIBG) myocardial uptake, myocardial perfusion (thallium 201 [201Tl] or technetium [Tc] 99m-tetrofosmin myocardial single photon emission computed tomography [SPECT]), and metabolism (fluorine 18-fluorodeoxyglucose positron emission tomography).Inflammatory status and brain natriuretic peptide (BNP) levels in 17 patients with TTC were compared with 14 age-matched patients. In TTC, elevated levels of CRP were evidenced on admission, reaching a peak in the following days (P.01). CRP levels were correlated to baseline left ventricular ejection fraction (LVEF) and BNP levels (P.05). Leukocytes were correlated to BNP and noradrenaline levels. Myocardial 123I-mIBG SPECT showed a reduced activity in the midventricle and apex corresponding to 35% +/- 23% of the total myocardial mass, partially reversible at follow-up. An identical pattern was retrieved when assessing myocardial glucose metabolism. At rest, no relevant abnormalities of myocardial perfusion could be evidenced at the subacute phase.Inflammatory status in TTC was related to LVEF impairment and to the extent of neurohormonal activation. The hypothesis of a catecholamine-induced myocardial "stunning" is emphasized by the evidence of a reduced 123I-mIBG myocardial activity, impairment of myocardial glucose metabolism, and wall motion kinetic after the same temporospatial distribution.

Background Takotsubo cardiomyopathy (TTC) is a novel heart disease, mimicking acute myocardial infarction. The term "transient left ventricular dysfunction syndrome" (TLVDS) seems to be more appropriate since variant forms of TTC sparing apical segments (mid-ventricular ballooning syndrome (MVBS) and inverted TTC) have been described. Patho-physiological bases of TLVDS remain poorly understood and its optimal management is until now empirical. Our aim was to characterize patho-physiological mechanisms of TLVDS by means of nuclear medicine procedures and to discuss the clinical usefulness of isotopic imaging for a non-invasive diagnosis of TLVDS. Methods and results During the sub acute phase, eighteen patients with TLVDS (13 TTC and 5 MVBS) underwent myocardial 99m Tc-tetrofosmin or 201 Thallium Gated Single Photon Emission Computed Tomography (G-SPECT) ( n =11), 123 I-mIBG SPECT ( n =8) and 18 F-FDG Gated Positron Emission Tomography (G-PET) ( n =15), assessing respectively LV perfusion, sympathetic innervation and glucose metabolism. Hypocontractile LV segments were characterized by normal perfusion but reduced uptake of 18 F-FDG and 123 I-mIBG. Topography and extent of metabolic defects and innervation abnormalities were largely overlapping. Follow-up 123 I-mIBG SPECT and 18 F-FDG G-PET were performed in selected patients showing rapid normalization of LV motion and progressive improvement of both glucose metabolism and sympathetic innervation. Discussion With the hypothesis of neurogenic stunned myocardium as the central causative mechanism of TLVDS, 123 I-mIBG SPECT seems to be the most specific diagnostic technique. Sympathetic function and glucose metabolism seem to be strictly correlated in the hypocontractile LV segments. Finally, our results underline the role of nuclear imaging in the setting of patho-physiological mechanisms of TLVDS.

The knowledge of in vivo brain tissue mechanical properties is essential in several biomedical engineering fields, such as injury biomechanics and neurosurgery simulation. Almost all existing available data have been obtained in vitro by invasive experimental protocols. However, the difference between in vivo and post-mortem mechanical properties remains poorly known, essentially due to the lack of a common method that could measure them both in vivo and ex vivo. In this study, we report the use of magnetic resonance elastography (MRE) for the non-invasive assessment of in vivo brain tissue viscoelastic properties and for the investigation of their evolution after the death. Experiments were performed on seven adult male rats. Shear storage and loss moduli were measured in vivo, just after death and at post-mortem time of ≈ 24 h . A significant increase in shear storage modulus G ′ of approximately 100% was found to occur just after death ( p = 0.002 ), whereas no significant difference was found between in vivo G ′ and G ′ at 24 h post-mortem time. No significant difference was found between shear loss modulus G ″ in vivo and just after death, whereas a decrease of about 50% was found to occur after 24 h ( p = 0.02 ). These results illustrate the ability of MRE to investigate some of the critical soft tissue biomechanics-related issues, as it can be used as a non-invasive tool for measuring soft tissue viscoelastic properties.