Fibrous dysplasia of the temporal bone : a case from the Glen Williams ossuary, Ontario, Canada

International audienc

Liver iron overload assessment by T 2 magnetic resonance imaging in pediatric patients: an accuracy and reproducibility study

This is the peer reviewed version of the following article: Cheng, H. L.M., Holowka, S., Moineddin, R. and Odame, I. (2012), Liver iron overload assessment by T 2 magnetic resonance imaging in pediatric patients: An accuracy and reproducibility study. Am. J. Hematol., 87: 435-437. doi:10.1002/ajh.23114, which has been published in final form at https://doi.org/10.1002/ajh.23114. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.T2 magnetic resonance imaging (MRI) provides rapid quantification of liver iron content (LIC). The reciprocal of T2 is directly proportional to iron and has been calibrated against LIC. There has, however, been few independent validation of the T2 method in a clinical setting. In 100 MRI studies on 75 pediatric patients being investigated for liver iron overload, we assess the accuracy and reproducibility of T2-measured LIC, using regulatory approved T2-based FerriScan1 for reference measurements. Results from independent analyses by two observers demonstrated robust inter- and intra-observer agreement (intraclass correlation coefficient (ICC) 5 0.99 and 1.0, respectively). T2-measured and reference LIC were strongly correlated (r 5 0.94, P < 0.0001), with a regression slope of 0.97 over the range 0–25 mg Fe/g. The T2 technique is shown to be accurate and reproducible for rapid, non-invasive LIC quantification

Subcortical alterations in tissue microstructure adjacent to focal cortical dysplasia: Detection at diffusion-tensor MR imaging by using magnetoencephalographic dipole cluster localization

Purpose: To determine whether changes at diffusion-tensor magnetic resonance (MR) imaging were present in children with intractable epilepsy and focal cortical dysplasia (FCD) in (a) subcortical white matter subjacent to MR imaging–visible areas of FCD, (b) subcortical white matter beyond the MR imaging–visible abnormality but subjacent to a magnetoencephalographic (MEG) dipole cluster, and (c) deep white matter tracts. Materials and Methods: The study protocol had institutional research ethics board approval, and written informed consent was obtained. Fifteen children with FCD and intractable epilepsy (mean age, 11.6 years; range, 3.6–18.3 years) underwent diffusion-tensor MR imaging and MEG. Regions of interest were placed in (a) the subcortical white matter subjacent to the MR imaging–visible abnormality, as well as the contralateral side; (b) the subcortical white matter beyond the MR imaging–visible abnormality but subjacent to a MEG dipole cluster, as well as the contralateral side; and (c) deep white matter tracts projecting to or from the MR imaging–visible FCD, as well as the contralateral side. Fractional anisotropy (FA), mean diffusivity, and eigenvalues (λ1, λ2, λ3) were evaluated. Results: Eleven of 15 children had MEG dipole clusters, and four children had MEG scatter. There were significant differences in FA, mean diffusivity, λ2, and λ3 of the subcortical white matter subjacent to the MR imaging–visible FCD (P < .001 for all), as well as that beyond the MR imaging–visible FCD but subjacent to a MEG dipole cluster (P = .001, P = .036, P < .001, and P = .002, respectively), compared with the contralateral side. There were also significant differences in FA (P < .001), mean diffusivity (P = .008), λ2 (P < .001), and λ3 (P = .001) of the deep white matter tracts projecting to or from the MR imaging–visible FCD compared with the contralateral side. Conclusion: With use of MEG dipole clusters to localize the epileptogenic zone, diffusion-tensor imaging can help identify alterations in tissue microstructure beyond the MR imaging–visible FCD

Real-Time Cross-Correlation Image Analysis of Early Events in IgE Receptor Signaling

Signaling in mast cells and basophils is mediated through IgE and its high affinity cell surface receptor, FcεRI. Crosslinking of the receptors by a cognate multivalent antigen leads to degranulation and release of mediators of the allergic immune response. Using multicolor fluorescence confocal microscopy, we probed the spatio-temporal dynamics of early events in the IgE receptor signal cascade. We monitored the recruitment of GFP-/CFP-labeled signaling proteins by acquiring sequential images with time resolution of 3 s during stimulation of RBL-2H3 mast cells with multivalent antigen. A fluorescent tag on the antigen allowed us to visualize the plasma membrane localization of crosslinked receptors, and fluorescent cholera toxin B served as a plasma membrane marker. We developed an automated image analysis scheme to quantify the recruitment of fluorescent intracellular proteins to the plasma membrane and to assess the time-dependent colocalization of these and other membrane-associated proteins with crosslinked receptors as measured by cross-correlation between the plasma membrane distributions of the two fluorophores. This automated method permits analysis of thousands of individual images from multiple experiments for each cross-correlation pair. We systematically applied this analysis to characterize stimulated interactions of IgE receptors with several signaling proteins, including the tyrosine kinases Lyn and Syk, and the adaptor protein LAT. Notably, for Syk-CFP we observed a rapid stimulated translocation to the plasma membrane but very little colocalization with aggregated receptors. Our results demonstrate the utility of this simple, automated method to monitor protein interactions quantitatively during cell signaling

Easing anxiety in preparation for pediatric magnetic resonance imaging: a pilot study using animal-assisted therapy

Background: Children undergoing magnetic resonance imaging (MRI) can experience negative emotions both before and during their scan, causing them to move and often necessitating the use of procedural sedation. Several strategies to improve patient compliance have been attempted. Objective: This study was designed to evaluate the effectiveness of a non-pharmacological intervention to reduce anxiety in pediatric patients preparing for MRI using animal-assisted therapy. Materials and methods: An animal intervention pilot study was performed in patients who agreed in advance to interact with a dog. Patients and caregivers filled out questionnaires, including questions designed to capture changes in patient emotion before and after the intervention. MRI diagnostic quality was compared to age- and gender-matched control groups with and without general anesthesia. Results: The intervention in 21 patients comparing pre- and post-scan surveys demonstrated a statistically significant improvement in patient anxiety levels (