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1.
Automated segmentation of midbrain structures with high iron content.
Garzón, B, Sitnikov, R, Bäckman, L, Kalpouzos, G
NeuroImage. 2018;:199-209
Abstract
The substantia nigra (SN), the subthalamic nucleus (STN), and the red nucleus (RN) are midbrain structures of ample interest in many neuroimaging studies, which may benefit from the availability of automated segmentation methods. The high iron content of these structures awards them high contrast in quantitative susceptibility mapping (QSM) images. We present a novel segmentation method that leverages the information of these images to produce automated segmentations of the SN, STN, and RN. The algorithm builds a map of spatial priors for the structures by non-linearly registering a set of manually-traced training labels to the midbrain. The priors are used to inform a Gaussian mixture model of the image intensities, with smoothness constraints imposed to ensure anatomical plausibility. The method was validated on manual segmentations from a sample of 40 healthy younger and older subjects. Average Dice scores were 0.81 (0.05) for the SN, 0.66 (0.14) for the STN and 0.88 (0.04) for the RN in the left hemisphere, and similar values were obtained for the right hemisphere. In all structures, volumes of manual and automatically obtained segmentations were significantly correlated. The algorithm showed lower accuracy on R2* and T2-weighted Fluid Attenuated Inversion Recovery (FLAIR) images, which are also sensitive to iron content. To illustrate an application of the method, we show that the automated segmentations were comparable to the manual ones regarding detection of age-related differences to putative iron content.
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Multi-Channel Acquisition for Isotropic Resolution in Magnetic Particle Imaging.
Lu, K, Goodwill, P, Zheng, B, Conolly, S
IEEE transactions on medical imaging. 2018;(9):1989-1998
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Abstract
Magnetic Particle Imaging (MPI), a molecular imaging modality that images biocompatible superparamagnetic iron oxide tracers, is well-suited for clinical angiography, in vivo cell tracking, cancer detection, and inflammation imaging. MPI is sensitive and quantitative to tracer concentration, with a positive contrast that is not attenuated or corrupted by tissue background. Like other clinical imaging techniques, such as computed tomography, magnetic resonance imaging, and nuclear medicine, MPI can be modeled as a linear and shift-invariant system with a well-defined point spread function (PSF) capturing the system blur. The key difference, as we show here, is that the MPI PSF is highly dependent on scanning parameters and is anisotropic using only a single-imaging trajectory. This anisotropic resolution poses a major challenge for clear and accurate clinical diagnosis. In this paper, we generalize a tensor imaging theory for multidimensional x-space MPI to explore the physical source of this anisotropy, present a multi-channel scanning algorithm to enable isotropic resolution, and experimentally demonstrate isotropic MPI resolution through the construction and the use of two orthogonal excitation and detector coil pairs.
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Diabetic Retinopathy Diagnosis from Retinal Images Using Modified Hopfield Neural Network.
Hemanth, DJ, Anitha, J, Son, LH, Mittal, M
Journal of medical systems. 2018;(12):247
Abstract
Disease diagnosis from medical images has become increasingly important in medical science. Abnormality identification in retinal images has become a challenging task in medical science. Effective machine learning and soft computing methods should be used to facilitate Diabetic Retinopathy Diagnosis from Retinal Images. Artificial Neural Networks are widely preferred for Diabetic Retinopathy Diagnosis from Retinal Images. It was observed that the conventional neural networks especially the Hopfield Neural Network (HNN) may be inaccurate due to the weight values are not adjusted in the training process. This paper presents a new Modified Hopfield Neural Network (MHNN) for abnormality classification from human retinal images. It relies on the idea that both weight values and output values can be adjusted simultaneously. The novelty of the proposed method lies in the training algorithm. In conventional method, the weights remain fixed but the weights are changing in the proposed method. Experimental performed on the Lotus Eye Care Hospital containing 540 images collected showed that the proposed MHNN yields an average sensitivity and specificity of 0.99 and accuracy of 99.25%. The proposed MHNN is better than HNN and other neural network approaches for Diabetic Retinopathy Diagnosis from Retinal Images.
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Quantitative susceptibility mapping as a monitoring biomarker in cerebral cavernous malformations with recent hemorrhage.
Zeineddine, HA, Girard, R, Cao, Y, Hobson, N, Fam, MD, Stadnik, A, Tan, H, Shen, J, Chaudagar, K, Shenkar, R, et al
Journal of magnetic resonance imaging : JMRI. 2018;(4):1133-1138
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Abstract
BACKGROUND Quantitative Susceptibility Mapping (QSM) MRI allows accurate assessment of iron content in cerebral cavernous malformations (CCM), and a threshold increase by 6% in QSM has been shown to reflect new symptomatic hemorrhage (SH) in previously stable lesions. PURPOSE/HYPOTHESIS It is unclear how lesional QSM evolves in CCMs after recent SH, and whether this could serve as a monitoring biomarker in clinical trials aimed at preventing rebleeding in these lesions. STUDY TYPE This is a prospective observational cohort study. POPULATION 16 CCM patients who experienced a SH within the past year, whose lesion was not resected or irradiated. FIELD STRENGTH/SEQUENCE The data acquisition was performed using QSM sequence implemented on a 3T MRI system ASSESSMENT The lesional QSM assessments at baseline and yearly during 22 patient-years of follow-up were performed by a trained research staff including imaging scientists. STATISTICAL TESTS Biomarker changes were assessed in relation to clinical events. Clinical trial modeling was performed using two-tailed tests of time-averaged difference (assuming within-patient correlation of 0.8, power = 0.9 and alpha = 0.1) to detect 20%, 30% or 50% effects of intervention on clinical and biomarkers event rates during two years of follow-up. RESULTS The change in mean lesional QSM of index hemorrhagic lesions was +7.93% per patient-year in the whole cohort. There were 5 cases (31%) of recurrent SH or lesional growth, and twice as many instances (62%) with a threshold (6%) increase in QSM. There were no instances of SH hemorrhage or lesional growth without an associated threshold increase in QSM during the same epoch. LEVEL OF EVIDENCE 1 Technical Efficacy: Stage 4 J. Magn. Reson. Imaging 2018;47:1133-1138.
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Intrasession and Between-Visit Variability of Retinal Vessel Density Values Measured with OCT Angiography in Diabetic Patients.
Czakó, C, Sándor, G, Ecsedy, M, Récsán, Z, Horváth, H, Szepessy, Z, Nagy, ZZ, Kovács, I
Scientific reports. 2018;(1):10598
Abstract
In clinical practice the measurement error of an instrument has special importance in analyzing and interpreting data, and acknowledging limitations. The purpose of this study was to evaluate intrasession and between-visit reproducibility of OCT angiography measurements in diabetic patients. A total of 54 eyes of 27 diabetic patients underwent OCT angiography imaging. Foveal avascular zone (FAZ) area and superficial retinal vessel density (VD) at 3 mm were calculated using the AngioAnalytics software. Three consecutive images were acquired at first visit and one image 1 month later. Intrasession and between-visit reproducibility of parameters were characterized by intraclass correlation coefficient (ICC), coefficient of variation (CV), and coefficient of repeatability (CR) values. We measured excellent (>0.90) ICC values both in intrasession and between-visit comparisons. CV was higher for the FAZ area compared to VD both in intrasession (7.79% vs. 2.87%) and in between-visit (12.33% vs. 2.95%) comparisons. Between-visit CR value for VD was 4.53% (95% CI: 3.72-5.79%). These data suggest that OCT angiography shows excellent repeatability in diabetic patients, indicating that this non-invasive technology might be suitable for longitudinal assessment of microvascular complications.
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Microcalcification morphological descriptors and parenchyma fractal dimension hierarchically interact in breast cancer: A diagnostic perspective.
Verma, G, Luciani, ML, Palombo, A, Metaxa, L, Panzironi, G, Pediconi, F, Giuliani, A, Bizzarri, M, Todde, V
Computers in biology and medicine. 2018;:1-6
Abstract
INTRODUCTION Herein, we propose a Systems Biology approach aimed at identifying quantitative morphological parameters useful in discriminating benign from malignant breast microcalcifications at digital mammography. MATERIALS AND METHODS The study includes 31 patients in which microcalcifications had been detected during XR mammography and were further confirmed by stereotactic (XR-guided) biopsies. Patients were classified according to the BIRADS (Breast Imaging-Reporting and Data System), along with their parenchyma fractal dimension and biopsy size. A geometrical-topological characterization of microcalcifications was obtained as well. RESULTS The 'size of biopsy' was the parameter endowed with the highest discriminant power between malignant and benign lesions thus confirming the reliability of surgeon judgment. The quantitative shape evaluation of both lesions and parenchyma allowed for a promising prediction of the BIRADS score. The area of lesions and parenchyma fractal dimension show a complex distribution for malignant breast calcifications that are consistent with their qualitative morphological pattern. Fractal dimension analysis enables the user to obtain reliable results as proved by its efficiency in the prediction of the morphology of breast cancer. CONCLUSION By reconstructing a phase-space distribution of biophysical parameters, different patterns of aggregation are recognized corresponding to different calcium deposition patterns, while the combination of tissue and microcalcification morphological descriptors provide a statistically significant prediction of tumour grade. CLINICAL RELEVANCE The development of an automated morphology evaluation system can help during clinical evaluation while also sketching mechanistic hypotheses of microcalcification generation.
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Image-based modeling and scoring of Howell-Jolly Bodies in human erythrocytes.
Angay, O, Friedrich, M, Pinnecker, J, Hintzsche, H, Stopper, H, Hempel, K, Heinze, KG
Cytometry. Part A : the journal of the International Society for Analytical Cytology. 2018;(3):305-313
Abstract
The spleen selectively removes cells with intracellular inclusions, for example, detached nuclear fragments in circulating erythrocytes, called Howell-Jolly Bodies (HJBs). With absent or deficient splenic function HJBs appear in the peripheral blood and can be used as a simple and non-invasive risk-indicator for fulminant potentially life-threatening infection after spleenectomy. However, it is still under debate whether counting of the rare HJBs is a reliable measure of splenic function. Investigating HJBs in premature erythrocytes from patients during radioiodine therapy gives about 10 thousand times higher HJB counts than in blood smears. However, we show that there is still the risk of false-positive results by unspecific nuclear remnants in the prepared samples that do not originate from HJBs, but from cell debris residing above or below the cell. Therefore, we present a method to improve accuracy of image-based tests that can be performed even in non-specialized medical institutions. We show how to selectively label HJB-like clusters in human blood samples and how to only count those that are undoubtedly inside the cell. We found a "critical distance" dcrit referring to a relative HJB-Cell distance that true HJBs do not exceed. To rule out false-positive counts we present a simple inside-outside-rule based on dcrit -a robust threshold that can be easily assessed by combining conventional 2D imaging and straight-forward image analysis. Besides data based on fluorescence imaging, simulations of randomly distributed HJB-like objects on realistically modelled cell objects demonstrate the risk and impact of biased counting in conventional analysis. © 2017 The Authors. Cytometry Part A published by Wiley Periodicals, Inc. on behalf of ISAC.
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Classification of Colorectal Cancer in Molecular Subtypes by Immunohistochemistry.
Ten Hoorn, S, Trinh, A, de Jong, J, Koens, L, Vermeulen, L
Methods in molecular biology (Clifton, N.J.). 2018;:179-191
Abstract
Colorectal cancer (CRC) is a heterogeneous disease, which can be categorized into distinct consensus molecular subtypes (CMSs). These subtypes differ in both clinical as well as biological properties. The gold-standard classification strategy relies on genome-wide expression data, which hampers widespread implementation. Here we describe an immunohistochemical (IHC) Mini Classifier, a practical tool that, in combination with microsatellite instability testing, delivers objective and accurate scoring to classify CRC patients into the main molecular disease subtypes. It is a robust immunohistochemical-based assay containing four specific stainings (FRMD6, ZEB1, HTR2B, and CDX2) in combination with cytokeratin. We also describe an online tool for classification of individual samples based on scoring parameters of these stainings.
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Myelin water fraction changes in febrile seizures.
Moldovan, K, Boxerman, JL, O'Muircheartaigh, J, Dean, D, Eyerly-Webb, S, Cosgrove, GR, Pucci, FG, Deoni, SCL, Spader, HS
Clinical neurology and neurosurgery. 2018;:61-67
Abstract
OBJECTIVE The objective of this feasibility study was to investigate whether myelin water fraction (MWF) patterns can differentiate children presenting with febrile seizures who will go on to develop nonfebrile epilepsy from those who will not. PATIENTS AND METHODS As part of a prospective study of myelination patterns in pediatric epilepsy, seven subjects with febrile seizures underwent magnetic resonance imaging (MRI) including the following standard sequences-T1-weighted, T2-weighted, fluid-attenuated inversion recovery (FLAIR)-and an additional experimental sequence, multicomponent-derived equilibrium single-pulse observation of T1 and T2 (mcDESPOT) to quantify MWF. For each of these subjects, MWF maps were derived and compared with an age-matched population-averaged MWF atlas. RESULTS All seven subjects (<5 years old) initially presented with febrile seizures. Of the seven, four had complex seizures and three had simple seizures. All of the children with simple febrile seizures had higher MWF compared with model-derived controls and did not develop epilepsy. All of the children with complex febrile seizures had lower MWF than their model-derived control, and two of these subjects later developed epilepsy. CONCLUSION This is the first study in which MWF maps were used to study children with febrile *seizures. This data suggests that relatively higher or stable MWF compared with normative data indicates a lower risk of nonfebrile epilepsy while relatively lower MWF may indicate a pathological condition that could lead to nonfebrile epilepsy.
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Establishing the overlap of IONP quantification with echo and echoless MR relaxation mapping.
Ring, HL, Zhang, J, Klein, ND, Eberly, LE, Haynes, CL, Garwood, M
Magnetic resonance in medicine. 2018;(3):1420-1428
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Abstract
PURPOSE Iron-oxide nanoparticles (IONPs) have shown tremendous utility for enhancing image contrast and delivering targeted therapies. Quantification of IONPs has been demonstrated at low concentrations with gradient echo (GRE) and spin echo (SE), and at high concentrations with echoless sequences such as swept imaging with Fourier transform (SWIFT). This work examines the overlap of IONP quantification with GRE, SE, and SWIFT. METHODS The limit of quantification of GRE, SE, inversion-recovery GRE, and SWIFT sequences was assessed using IONPs at a concentration range of 0.02 to 89.29 mM suspended in 1% agarose. Empirically derived limits of quantification were compared with International Union of Pure and Applied Chemistry definitions. Both commercial and experimental IONPs were used. RESULTS All three IONPs assessed demonstrated an overlap of concentration quantification with GRE, SE, and SWIFT sequences. The largest dynamic range observed was 0.004 to 35.7 mM with Feraheme. CONCLUSIONS The metrics established allow upper and lower quantitative limitations to be estimated given the relaxivity characteristics of the IONP and the concentration range of the material to be assessed. The methods outlined in this paper are applicable to any pulse sequence, IONP formulation, and field strength. Magn Reson Med 79:1420-1428, 2018. © 2017 International Society for Magnetic Resonance in Medicine.