Displaying publications 41 - 60 of 116 in total

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  1. Fadzli F, Ramli N, Ramli NM
    Clin Radiol, 2013 Oct;68(10):e538-51.
    PMID: 23932674 DOI: 10.1016/j.crad.2013.05.104
    Visual field defects are a conglomerate of patterns of visual impairment derived from diseases affecting the optic nerve as it extends from the globe to the visual cortex. They are complex signs requiring perimetry or visual confrontation for delineation and are associated with diverse aetiologies. This review considers the chiasmatic and post-chiasmatic causes of visual disturbances, with an emphasis on magnetic resonance imaging (MRI) techniques. Newer MRI sequences are considered, such as diffusion-tensor imaging. MRI images are correlated with perimetric findings in order to demonstrate localization of lesions in the visual pathway. This may serve as a valuable reference tool to clinicians and radiologists in the early diagnostic process of differentiating causes of various visual field defects in daily practice.
    Matched MeSH terms: Magnetic Resonance Imaging/methods*
  2. Tan SL, Rahmat K, Rozalli FI, Mohd-Shah MN, Aziz YF, Yip CH, et al.
    Clin Radiol, 2014 Jan;69(1):63-71.
    PMID: 24156797 DOI: 10.1016/j.crad.2013.08.007
    To investigate the capability and diagnostic accuracy of diffusion-weighted imaging (DWI) in differentiating benign from malignant breast lesions using 3 T magnetic resonance imaging (MRI).
    Matched MeSH terms: Diffusion Magnetic Resonance Imaging/methods*
  3. Adeshina AM, Hashim R, Khalid NE, Abidin SZ
    Interdiscip Sci, 2013 Mar;5(1):23-36.
    PMID: 23605637 DOI: 10.1007/s12539-013-0155-z
    In the medical diagnosis and treatment planning, radiologists and surgeons rely heavily on the slices produced by medical imaging devices. Unfortunately, these image scanners could only present the 3-D human anatomical structure in 2-D. Traditionally, this requires medical professional concerned to study and analyze the 2-D images based on their expert experience. This is tedious, time consuming and prone to error; expecially when certain features are occluding the desired region of interest. Reconstruction procedures was earlier proposed to handle such situation. However, 3-D reconstruction system requires high performance computation and longer processing time. Integrating efficient reconstruction system into clinical procedures involves high resulting cost. Previously, brain's blood vessels reconstruction with MRA was achieved using SurLens Visualization System. However, adapting such system to other image modalities, applicable to the entire human anatomical structures, would be a meaningful contribution towards achieving a resourceful system for medical diagnosis and disease therapy. This paper attempts to adapt SurLens to possible visualisation of abnormalities in human anatomical structures using CT and MR images. The study was evaluated with brain MR images from the department of Surgery, University of North Carolina, United States and CT abdominal pelvic, from the Swedish National Infrastructure for Computing. The MR images contain around 109 datasets each of T1-FLASH, T2-Weighted, DTI and T1-MPRAGE. Significantly, visualization of human anatomical structure was achieved without prior segmentation. SurLens was adapted to visualize and display abnormalities, such as an indication of walderstrom's macroglobulinemia, stroke and penetrating brain injury in the human brain using Magentic Resonance (MR) images. Moreover, possible abnormalities in abdominal pelvic was also visualized using Computed Tomography (CT) slices. The study shows SurLens' functionality as a 3-D Multimodal Visualization System.
    Matched MeSH terms: Magnetic Resonance Imaging/methods*
  4. Sim KS, Lai MA, Tso CP, Teo CC
    J Med Syst, 2011 Feb;35(1):39-48.
    PMID: 20703587 DOI: 10.1007/s10916-009-9339-9
    A novel technique to quantify the signal-to-noise ratio (SNR) of magnetic resonance images is developed. The image SNR is quantified by estimating the amplitude of the signal spectrum using the autocorrelation function of just one single magnetic resonance image. To test the performance of the quantification, SNR measurement data are fitted to theoretically expected curves. It is shown that the technique can be implemented in a highly efficient way for the magnetic resonance imaging system.
    Matched MeSH terms: Magnetic Resonance Imaging/methods*
  5. Yusof MI, Hassan E, Abdullah S
    Surg Radiol Anat, 2011 Mar;33(2):109-15.
    PMID: 20658232 DOI: 10.1007/s00276-010-0704-7
    Posterior translation of the spinal cord occurs passively following laminoplasty with the presence lordotic spine and availability of a space for the spinal cord to shift. This study is to predict the distance of posterior spinal cord migration after expansive laminoplasty at different cervical levels based on measurement of posterior translation of the spinal cord in normal cervical morphometry.
    Matched MeSH terms: Magnetic Resonance Imaging/methods*
  6. Sheaufung S, Taufiq A, Nawawi O, Naicker MS, Waran V
    J Clin Neurosci, 2009 Apr;16(4):579-81.
    PMID: 19201194 DOI: 10.1016/j.jocn.2008.04.029
    Neurenteric cysts are rare congenital spinal masses that result from the dysgenesis of the endoderm tissue during development. We report a 4-year-old girl who presented with an insidious onset of lower limb paraparesis. An MRI scan revealed a cervicothoracic intradural extramedullary neurenteric cyst at the thoracic T1/T2 level, with marked spinal cord compression. No associated spinal dysraphism was noted. The patient underwent laminotomy and excision of the cyst. She recovered her neurological functions completely post-operatively, and at her six-month follow-up she was asymptomatic without any neurological deficits. We will discuss the pathogenesis, clinical presentation, and neuroradiological findings. We emphasize the value of early surgical intervention and long-term follow-up when this type of lesion is only partially excised.
    Matched MeSH terms: Magnetic Resonance Imaging/methods
  7. Heberle LC, Al Tawari AA, Ramadan DG, Ibrahim JK
    Brain Dev, 2006 Jun;28(5):329-31.
    PMID: 16376514
    Ethylmalonic encephalopathy is a rare metabolic disease presenting in infancy with developmental delay, acrocyanosis, petechiae, chronic diarrhea and early death. The biochemical characteristics of this autosomal recessive disease are urinary organic acid abnormalities. Recently it has been found to be caused by mutations in the ETHE1 gene, located on Ch19q13. Only about 30 patients have been reported, and we describe two additional cases. The first patient showed a typical clinical picture and biochemical abnormalities, with additional atypical clinical features. Neuroimaging studies showed extensive changes. A new homozygous mutation in exon 3 of the ETHE1 gene was found. The second patient was not investigated genetically; however besides the typical clinical picture and biochemical profile he was found to have cytochrome C oxidase deficiency.
    Matched MeSH terms: Magnetic Resonance Imaging/methods
  8. Piaw CS, Kiam OT, Rapaee A, Khoon LC, Bang LH, Ling CW, et al.
    Cardiovasc Intervent Radiol, 2006 Mar-Apr;29(2):230-4.
    PMID: 16252078
    Transesophageal echocardiography (TEE) is a trusted method of sizing atrial septal defect (ASD) prior to percutaneous closure but is invasive, uncomfortable, and may carry a small risk of morbidity and mortality. Magnetic resonance imaging (MRI) may be useful non-invasive alternative in such patients who refuse or are unable to tolerate TEE and may provide additional information on the shape of the A0SD.
    Matched MeSH terms: Magnetic Resonance Imaging/methods*
  9. Ranganathan S, Moosa F, Kamarulzaman A, Looi LM
    Br J Radiol, 2005 Apr;78(928):353-4.
    PMID: 15774599
    Cryptococcus neoformans is a yeast like fungus, which is commonly found in bird droppings, especially pigeons. Most cases of cryptococcal infections occur in immunocompromised patients or in those who are on long term immunosuppressant therapies. Cryptococcal infection usually presents as a meningoencephalitis or a pulmonary infection. Skin, bone and genital infections are very rare. We report the second case of vaginal cryptococcossis to be reported in English literature and the first to be imaged with CT and MRI.
    Matched MeSH terms: Magnetic Resonance Imaging/methods
  10. Yazdani S, Yusof R, Karimian A, Mitsukira Y, Hematian A
    PLoS One, 2016;11(4):e0151326.
    PMID: 27096925 DOI: 10.1371/journal.pone.0151326
    Image segmentation of medical images is a challenging problem with several still not totally solved issues, such as noise interference and image artifacts. Region-based and histogram-based segmentation methods have been widely used in image segmentation. Problems arise when we use these methods, such as the selection of a suitable threshold value for the histogram-based method and the over-segmentation followed by the time-consuming merge processing in the region-based algorithm. To provide an efficient approach that not only produce better results, but also maintain low computational complexity, a new region dividing based technique is developed for image segmentation, which combines the advantages of both regions-based and histogram-based methods. The proposed method is applied to the challenging applications: Gray matter (GM), White matter (WM) and cerebro-spinal fluid (CSF) segmentation in brain MR Images. The method is evaluated on both simulated and real data, and compared with other segmentation techniques. The obtained results have demonstrated its improved performance and robustness.
    Matched MeSH terms: Magnetic Resonance Imaging/methods*
  11. Chow LS, Rajagopal H, Paramesran R, Alzheimer's Disease Neuroimaging Initiative
    Magn Reson Imaging, 2016 07;34(6):820-831.
    PMID: 26969762 DOI: 10.1016/j.mri.2016.03.006
    Medical Image Quality Assessment (IQA) plays an important role in assisting and evaluating the development of any new hardware, imaging sequences, pre-processing or post-processing algorithms. We have performed a quantitative analysis of the correlation between subjective and objective Full Reference - IQA (FR-IQA) on Magnetic Resonance (MR) images of the human brain, spine, knee and abdomen. We have created a MR image database that consists of 25 original reference images and 750 distorted images. The reference images were distorted with six types of distortions: Rician Noise, Gaussian White Noise, Gaussian Blur, DCT compression, JPEG compression and JPEG2000 compression, at various levels of distortion. Twenty eight subjects were chosen to evaluate the images resulting in a total of 21,700 human evaluations. The raw scores were then converted to Difference Mean Opinion Score (DMOS). Thirteen objective FR-IQA metrics were used to determine the validity of the subjective DMOS. The results indicate a high correlation between the subjective and objective assessment of the MR images. The Noise Quality Measurement (NQM) has the highest correlation with DMOS, where the mean Pearson Linear Correlation Coefficient (PLCC) and Spearman Rank Order Correlation Coefficient (SROCC) are 0.936 and 0.938 respectively. The Universal Quality Index (UQI) has the lowest correlation with DMOS, where the mean PLCC and SROCC are 0.807 and 0.815 respectively. Student's T-test was used to find the difference in performance of FR-IQA across different types of distortion. The superior IQAs tested statistically are UQI for Rician noise images, Visual Information Fidelity (VIF) for Gaussian blur images, NQM for both DCT and JPEG compressed images, Peak Signal-to-Noise Ratio (PSNR) for JPEG2000 compressed images.
    Matched MeSH terms: Magnetic Resonance Imaging/methods*
  12. Git KA, Fioravante LA, Fernandes JL
    Br J Radiol, 2015 Sep;88(1053):20150269.
    PMID: 26118302 DOI: 10.1259/bjr.20150269
    To assess whether an online open-source tool would provide accurate calculations of T2(*) values for iron concentrations in the liver and heart compared with a standard reference software.
    Matched MeSH terms: Magnetic Resonance Imaging/methods*
  13. Jahanzad Z, Liew YM, Bilgen M, McLaughlin RA, Leong CO, Chee KH, et al.
    Phys Med Biol, 2015 May 21;60(10):4015-31.
    PMID: 25919317 DOI: 10.1088/0031-9155/60/10/4015
    A segmental two-parameter empirical deformable model is proposed for evaluating regional motion abnormality of the left ventricle. Short-axis tagged MRI scans were acquired from 10 healthy subjects and 10 postinfarct patients. Two motion parameters, contraction and rotation, were quantified for each cardiac segment by fitting the proposed model using a non-rigid registration algorithm. The accuracy in motion estimation was compared to a global model approach. Motion parameters extracted from patients were correlated to infarct transmurality assessed with delayed-contrast-enhanced MRI. The proposed segmental model allows markedly improved accuracy in regional motion analysis as compared to the global model for both subject groups (1.22-1.40 mm versus 2.31-2.55 mm error). By end-systole, all healthy segments experienced radial displacement by ~25-35% of the epicardial radius, whereas the 3 short-axis planes rotated differently (basal: 3.3°; mid:  -1° and apical:  -4.6°) to create a twisting motion. While systolic contraction showed clear correspondence to infarct transmurality, rotation was nonspecific to either infarct location or transmurality but could indicate the presence of functional abnormality. Regional contraction and rotation derived using this model could potentially aid in the assessment of severity of regional dysfunction of infarcted myocardium.
    Matched MeSH terms: Magnetic Resonance Imaging/methods*
  14. Farzan A, Mashohor S, Ramli AR, Mahmud R
    Behav Brain Res, 2015 Sep 1;290:124-30.
    PMID: 25889456 DOI: 10.1016/j.bbr.2015.04.010
    Boosting accuracy in automatically discriminating patients with Alzheimer's disease (AD) and normal controls (NC), based on multidimensional classification of longitudinal whole brain atrophy rates and their intermediate counterparts in analyzing magnetic resonance images (MRI).
    Matched MeSH terms: Magnetic Resonance Imaging/methods*
  15. Seow P, Narayanan V, Hernowo AT, Wong JHD, Ramli N
    Neuroimage Clin, 2018;20:531-536.
    PMID: 30167373 DOI: 10.1016/j.nicl.2018.08.003
    Objectives: This study maps the lipid distributions based on magnetic resonance imaging (MRI) in-and opposed-phase (IOP) sequence and correlates the findings generated from lipid map to histological grading of glioma.

    Methods: Forty histologically proven glioma patients underwent a standard MRI tumour protocol with the addition of IOP sequence. The regions of tumour (solid enhancing, solid non-enhancing, and cystic regions) were delineated using snake model (ITK-SNAP) with reference to structural and diffusion MRI images. The lipid distribution map was constructed based on signal loss ratio (SLR) obtained from the IOP imaging. The mean SLR values of the regions were computed and compared across the different glioma grades.

    Results: The solid enhancing region of glioma had the highest SLR for both Grade II and III. The mean SLR of solid non-enhancing region of tumour demonstrated statistically significant difference between the WHO grades (grades II, III & IV) (mean SLRII = 0.04, mean SLRIII = 0.06, mean SLRIV = 0.08, & p 

    Matched MeSH terms: Magnetic Resonance Imaging/methods*
  16. Pszczolkowski S, Law ZK, Gallagher RG, Meng D, Swienton DJ, Morgan PS, et al.
    Comput Biol Med, 2019 03;106:126-139.
    PMID: 30711800 DOI: 10.1016/j.compbiomed.2019.01.022
    BACKGROUND: Spontaneous intracerebral haemorrhage (SICH) is a common condition with high morbidity and mortality. Segmentation of haematoma and perihaematoma oedema on medical images provides quantitative outcome measures for clinical trials and may provide important markers of prognosis in people with SICH.

    METHODS: We take advantage of improved contrast seen on magnetic resonance (MR) images of patients with acute and early subacute SICH and introduce an automated algorithm for haematoma and oedema segmentation from these images. To our knowledge, there is no previously proposed segmentation technique for SICH that utilises MR images directly. The method is based on shape and intensity analysis for haematoma segmentation and voxel-wise dynamic thresholding of hyper-intensities for oedema segmentation.

    RESULTS: Using Dice scores to measure segmentation overlaps between labellings yielded by the proposed algorithm and five different expert raters on 18 patients, we observe that our technique achieves overlap scores that are very similar to those obtained by pairwise expert rater comparison. A further comparison between the proposed method and a state-of-the-art Deep Learning segmentation on a separate set of 32 manually annotated subjects confirms the proposed method can achieve comparable results with very mild computational burden and in a completely training-free and unsupervised way.

    CONCLUSION: Our technique can be a computationally light and effective way to automatically delineate haematoma and oedema extent directly from MR images. Thus, with increasing use of MR images clinically after intracerebral haemorrhage this technique has the potential to inform clinical practice in the future.

    Matched MeSH terms: Magnetic Resonance Imaging/methods*
  17. Viprakasit V, Ajlan A, Aydinok Y, Al Ebadi BAA, Dewedar H, Ibrahim AS, et al.
    Am J Hematol, 2018 06;93(6):E135-E137.
    PMID: 29473204 DOI: 10.1002/ajh.25075
    Matched MeSH terms: Magnetic Resonance Imaging/methods*
  18. Acharya UR, Fernandes SL, WeiKoh JE, Ciaccio EJ, Fabell MKM, Tanik UJ, et al.
    J Med Syst, 2019 Aug 09;43(9):302.
    PMID: 31396722 DOI: 10.1007/s10916-019-1428-9
    The aim of this work is to develop a Computer-Aided-Brain-Diagnosis (CABD) system that can determine if a brain scan shows signs of Alzheimer's disease. The method utilizes Magnetic Resonance Imaging (MRI) for classification with several feature extraction techniques. MRI is a non-invasive procedure, widely adopted in hospitals to examine cognitive abnormalities. Images are acquired using the T2 imaging sequence. The paradigm consists of a series of quantitative techniques: filtering, feature extraction, Student's t-test based feature selection, and k-Nearest Neighbor (KNN) based classification. Additionally, a comparative analysis is done by implementing other feature extraction procedures that are described in the literature. Our findings suggest that the Shearlet Transform (ST) feature extraction technique offers improved results for Alzheimer's diagnosis as compared to alternative methods. The proposed CABD tool with the ST + KNN technique provided accuracy of 94.54%, precision of 88.33%, sensitivity of 96.30% and specificity of 93.64%. Furthermore, this tool also offered an accuracy, precision, sensitivity and specificity of 98.48%, 100%, 96.97% and 100%, respectively, with the benchmark MRI database.
    Matched MeSH terms: Magnetic Resonance Imaging/methods
  19. Syed Nasser N, Ibrahim B, Sharifat H, Abdul Rashid A, Suppiah S
    J Clin Neurosci, 2019 Jul;65:87-99.
    PMID: 30955950 DOI: 10.1016/j.jocn.2019.03.054
    Functional magnetic resonance imaging (fMRI) is a non-invasive imaging modality that enables the assessment of neural connectivity and oxygen utility of the brain using blood oxygen level dependent (BOLD) imaging sequence. Electroencephalography (EEG), on the other hands, looks at cortical electrical impulses of the brain thus detecting brainwave patterns during rest and thought processing. The combination of these two modalities is called fMRI with simultaneous EEG (fMRI-EEG), which has emerged as a new tool for experimental neuroscience assessments and has been applied clinically in many settings, most commonly in epilepsy cases. Recent advances in imaging has led to fMRI-EEG being utilized in behavioural studies which can help in giving an objective assessment of ambiguous cases and help in the assessment of response to treatment by providing a non-invasive biomarker of the disease processes. We aim to review the role and interpretation of fMRI-EEG in studies pertaining to psychiatric disorders and behavioral abnormalities.
    Matched MeSH terms: Magnetic Resonance Imaging/methods*
  20. Foo LS, Yap WS, Hum YC, Manan HA, Tee YK
    J Magn Reson, 2020 01;310:106648.
    PMID: 31760147 DOI: 10.1016/j.jmr.2019.106648
    Chemical exchange saturation transfer (CEST) magnetic resonance imaging (MRI) holds great potential to provide new metabolic information for clinical applications such as tumor, stroke and Parkinson's Disease diagnosis. Many active research and developments have been conducted to translate this emerging MRI technique for routine clinical applications. In general, there are two CEST quantification techniques: (i) model-free and (ii) model-based techniques. The reliability of these quantification techniques depends heavily on the experimental conditions and quality of the collected data. Errors such as noise may lead to misleading quantification results and thus inaccurate diagnosis when CEST imaging becomes a standard or routine imaging scan in the future. This paper investigates the accuracy and robustness of these quantification techniques under different signal-to-noise (SNR) levels and magnetic field strengths. The quantified CEST effect before and after adding random Gaussian White Noise using model-free and model-based quantification techniques were compared. It was found that the model-free technique consistently yielded larger average percentage error across all tested parameters compared to its model-based counterpart, and that the model-based technique could withstand SNR of about 3 times lower than the model-free technique. When applied on noisy brain tumor, ischemic stroke, and Parkinson's Disease clinical data, the model-free technique failed to produce significant differences between normal and abnormal tissue whereas the model-based technique consistently generated significant differences. Although the model-free technique was less accurate and robust, its simplicity and thus speed would still make it a good approximate when the SNR was high (>50) or when the CEST effect was large and well-defined. For more accurate CEST quantification, model-based techniques should be considered. When SNR was low (<50) and the CEST effect was small such as those acquired from clinical field strength scanners, which are generally 3T and below, model-based techniques should be considered over model-free counterpart to maintain an average percentage error of less than 44% even under very noisy condition as tested in this work.
    Matched MeSH terms: Magnetic Resonance Imaging/methods*
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