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1.
AJNR Am J Neuroradiol ; 35(1): 170-5, 2014 Jan.
Article in English | MEDLINE | ID: mdl-23868150

ABSTRACT

BACKGROUND AND PURPOSE: DWI has been increasingly used to characterize orbital masses and provides quantitative information in the form of the ADC, but studies of DWI of orbital masses have shown a range of reported sensitivities, specificities, and optimal threshold ADC values for distinguishing benign from malignant lesions. Our goal was to determine the optimal use of DWI for imaging orbital masses through aggregation of data from multiple centers. MATERIALS AND METHODS: Source data from 3 previous studies of orbital mass DWI were aggregated, and additional published data points were gathered. Receiver operating characteristic analysis was performed to determine the sensitivity, specificity, and optimal ADC thresholds for distinguishing benign from malignant masses. RESULTS: There was no single ADC threshold that characterized orbital masses as benign or malignant with high sensitivity and specificity. An ADC of less than 0.93 × 10(-3) mm(2)/s was more than 90% specific for malignancy, and an ADC of less than 1.35 × 10(-3) mm(2)/s was more than 90% sensitive for malignancy. With these 2 thresholds, 33% of this cohort could be characterized as "likely malignant," 29% as "likely benign," and 38% as "indeterminate." CONCLUSIONS: No single ADC threshold is highly sensitive and specific for characterizing orbital masses as benign or malignant. If we used 2 thresholds to divide these lesions into 3 categories, however, a majority of orbital masses can be characterized with >90% confidence.


Subject(s)
Diffusion Magnetic Resonance Imaging/methods , Image Interpretation, Computer-Assisted/methods , Models, Statistical , Orbital Neoplasms/pathology , Statistics as Topic , Computer Simulation , Female , Humans , Male , Reproducibility of Results , Sensitivity and Specificity
2.
AJNR Am J Neuroradiol ; 33(2): 314-9, 2012 Feb.
Article in English | MEDLINE | ID: mdl-22116113

ABSTRACT

BACKGROUND AND PURPOSE: Ocular masses represent a spectrum of malignant tumors and benign lesions that are sometimes difficult to detect and differentiate by conventional imaging techniques. The aim of this study was to characterize a group of malignant ocular masses with DWI, with the goals of establishing reference data and identifying potential clinical applications for improved noninvasive characterization. MATERIALS AND METHODS: With institutional review board approval, 26 malignant ocular masses in 22 patients were retrospectively analyzed. Five masses were excluded from further analysis due to nonvisualization. Fifteen retinoblastomas, 5 melanomas, and 1 highly undifferentiated carcinoma were studied. Region-of-interest analysis was performed, and the ADC of each mass was measured and also compared with a normal-appearing thalamus. Lesion thickness was measured, the amount of susceptibility artifact was qualitatively assessed and graded, and the correlation between these factors and retinoblastoma ADC was determined. RESULTS: Retinoblastomas had an ADC of 0.93 ± 0.3 × 10(-3) mm(2)/s (mean). Melanoma had an ADC of 1.18 ± 0.16 × 10(-3) mm(2)/s. The ADC of retinoblastoma was strongly inversely correlated with lesion thickness, likely representing the effect of partial volume averaging. ADC was not correlated with the amount of subjectively determined susceptibility artifact. CONCLUSIONS: Malignant ocular tumors were consistently characterized with DWI, though with limitations due to artifact and partial volume averaging. Additional description of DWI of ocular masses and further technical improvements may lead to a clinical role for DWI.


Subject(s)
Diffusion Magnetic Resonance Imaging , Eye Neoplasms/diagnosis , Orbital Neoplasms/diagnosis , Adolescent , Adult , Aged , Aged, 80 and over , Child , Child, Preschool , Female , Humans , Infant , Male , Middle Aged , Retrospective Studies , Young Adult
3.
Neuron ; 23(3): 583-92, 1999 Jul.
Article in English | MEDLINE | ID: mdl-10433269

ABSTRACT

Shank is a recently described family of postsynaptic proteins that function as part of the NMDA receptor-associated PSD-95 complex (Naisbitt et al., 1999 [this issue of Neuron]). Here, we report that Shank proteins also bind to Homer. Homer proteins form multivalent complexes that bind proline-rich motifs in group 1 metabotropic glutamate receptors and inositol trisphosphate receptors, thereby coupling these receptors in a signaling complex. A single Homer-binding site is identified in Shank, and Shank and Homer coimmunoprecipitate from brain and colocalize at postsynaptic densities. Moreover, Shank clusters mGluR5 in heterologous cells in the presence of Homer and mediates the coclustering of Homer with PSD-95/GKAP. Thus, Shank may cross-link Homer and PSD-95 complexes in the PSD and play a role in the signaling mechanisms of both mGluRs and NMDA receptors.


Subject(s)
Adaptor Proteins, Signal Transducing , Carrier Proteins/metabolism , Nerve Tissue Proteins/metabolism , Neurons/chemistry , Neuropeptides/metabolism , Receptors, Metabotropic Glutamate/metabolism , Animals , Binding Sites/physiology , COS Cells , Calcium/metabolism , Calcium Channels/metabolism , Carrier Proteins/chemistry , Carrier Proteins/genetics , Disks Large Homolog 4 Protein , Homer Scaffolding Proteins , Humans , Inositol 1,4,5-Trisphosphate Receptors , Intracellular Signaling Peptides and Proteins , Kidney/cytology , Membrane Proteins , Microscopy, Immunoelectron , Mutagenesis, Site-Directed/physiology , Neurons/metabolism , Neuropeptides/chemistry , Proline/metabolism , Protein Structure, Tertiary , Rabbits , Rats , Receptors, Cytoplasmic and Nuclear/metabolism , Receptors, N-Methyl-D-Aspartate/metabolism , SAP90-PSD95 Associated Proteins , Synapses/chemistry , Synapses/metabolism , Synapses/ultrastructure , Transfection
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