Displaying publications 1 - 20 of 545 in total

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  1. Nasaruddin, N.H., Yusoff, A.N., Sharanjeet Kaur, Nasrudin, N.F., Muda, S.
    MyJurnal
    Ocular abnormalities have apparent effects on brain activation. However, neuroimaging data about the ocular characteristics of healthy participants are still lacking to be compared with data for patients with ocular pathology. The objective of this multiple participants’ functional magnetic resonance imaging (fMRI) studies was to investigate the brain activation characteristics of healthy participants when they view stimuli of various shapes, pattern and size. During the fMRI scans, the participants view the growing ring, rotating wedge, flipping hour glass/bow tie, quadrant arc and full checker board stimuli. All stimuli have elements of black-and-white checkerboard pattern. Statistical parametric mapping (SPM) was used in generating brain activation via fixed-effects (FFX) and conjunction analyses. The stimuli of various shapes, pattern and size produce different brain activation with more activation concentrated in the left hemisphere. These results are supported by the conjunction analysis which indicated that the left pre-central, post-central, superior temporal and occipital gyrus as well as the left cingulate cortices were involved when the participants viewed each given stimulus. Differential activation analysis showed activation with high specificity in the occipital region due to the stimuli of various shapes, pattern and size. The activation in the right middle temporal gyrus was found to be significantly higher in response to moving stimuli as compared to stationary stimuli. This confi rms the involvement of the right middle temporal gyrus in the observation of movements. The black-and-white checkerboard stimuli of various shapes, pattern and size, stationary and moving was found to 1) activate visual as well as other cortices in temporal and parietal lobes, 2) cause asymmetry in brain function and 3) exhibit functional integration characteristics in several brain areas.
    Keywords: fMRI; SPM; visual stimulus; occipital gyrus; middle temporal gyrus
    Matched MeSH terms: Magnetic Resonance Imaging
  2. Abdullah BJ, Bux SI, Chien D
    Med. J. Malaysia, 1997 Dec;52(4):445-53; quiz 454.
    PMID: 10968127
    MRI is now an important diagnostic tool in medical management. There are numerous safety issues to be considered by the clinicians prior to requesting an MRI examination for their patients. These include those related to the magnetic field, gradient magnetic fields, the patient and contrast medium. This paper discusses the dangers and necessary precautions essential to reduce the risk of untoward complications from MRI.
    Matched MeSH terms: Magnetic Resonance Imaging/adverse effects*
  3. Liong CC, Rahmat K, Mah JS, Lim SY, Tan AH
    Can J Neurol Sci, 2016 Sep;43(5):719-20.
    PMID: 27670213 DOI: 10.1017/cjn.2016.269
    Matched MeSH terms: Magnetic Resonance Imaging*
  4. Choong MK, Logeswaran R, Bister M
    J Med Syst, 2006 Jun;30(3):139-43.
    PMID: 16848126
    This paper attempts to improve the diagnostic quality of magnetic resonance (MR) images through application of lossy compression as a noise-reducing filter. The amount of imaging noise present in MR images is compared with the amount of noise introduced by the compression, with particular attention given to the situation where the compression noise is a fraction of the imaging noise. A popular wavelet-based algorithm with good performance, Set Partitioning in Hierarchical Trees (SPIHT), was employed for the lossy compression. Tests were conducted with a number of MR patient images and corresponding phantom images. Different plausible ratios between imaging noise and compression noise (ICR) were considered, and the achievable compression gain through the controlled lossy compression was evaluated. Preliminary results show that at certain ICR's, it becomes virtually impossible to distinguish between the original and compressed-decompressed image. Radiologists presented with a blind test, in certain cases, showed preference to the compressed image rather than the original uncompressed ones, indicating that under controlled circumstances, lossy image compression can be used to improve the diagnostic quality of the MR images.
    Matched MeSH terms: Magnetic Resonance Imaging/methods*
  5. Gandhamal A, Talbar S, Gajre S, Razak R, Hani AFM, Kumar D
    Comput. Biol. Med., 2017 Sep 01;88:110-125.
    PMID: 28711767 DOI: 10.1016/j.compbiomed.2017.07.008
    Knee osteoarthritis (OA) progression can be monitored by measuring changes in the subchondral bone structure such as area and shape from MR images as an imaging biomarker. However, measurements of these minute changes are highly dependent on the accurate segmentation of bone tissue from MR images and it is challenging task due to the complex tissue structure and inadequate image contrast/brightness. In this paper, a fully automated method for segmenting subchondral bone from knee MR images is proposed. Here, the contrast of knee MR images is enhanced using a gray-level S-curve transformation followed by automatic seed point detection using a three-dimensional multi-edge overlapping technique. Successively, bone regions are initially extracted using distance-regularized level-set evolution followed by identification and correction of leakages along the bone boundary regions using a boundary displacement technique. The performance of the developed technique is evaluated against ground truths by measuring sensitivity, specificity, dice similarity coefficient (DSC), average surface distance (AvgD) and root mean square surface distance (RMSD). An average sensitivity (91.14%), specificity (99.12%) and DSC (90.28%) with 95% confidence interval (CI) in the range 89.74-92.54%, 98.93-99.31% and 88.68-91.88% respectively is achieved for the femur bone segmentation in 8 datasets. For tibia bone, average sensitivity (90.69%), specificity (99.65%) and DSC (91.35%) with 95% CI in the range 88.59-92.79%, 99.50-99.80% and 88.68-91.88% respectively is achieved. AvgD and RMSD values for femur are 1.43 ± 0.23 (mm) and 2.10 ± 0.35 (mm) respectively while for tibia, the values are 0.95 ± 0.28 (mm) and 1.30 ± 0.42 (mm) respectively that demonstrates acceptable error between proposed method and ground truths. In conclusion, results obtained in this work demonstrate substantially significant performance with consistency and robustness that led the proposed method to be applicable for large scale and longitudinal knee OA studies in clinical settings.
    Matched MeSH terms: Magnetic Resonance Imaging/methods*
  6. Subudhi A, Acharya UR, Dash M, Jena S, Sabut S
    Comput. Biol. Med., 2018 12 01;103:116-129.
    PMID: 30359807 DOI: 10.1016/j.compbiomed.2018.10.016
    It is difficult to develop an accurate algorithm to detect the stroke lesions using magnetic resonance imaging (MRI) images due to variation in different lesion sizes, variation in morphological structure, and similarity in intensity of lesion with normal brain in three types of stroke, namely partial anterior circulation syndrome (PACS), lacunar syndrome (LACS) and total anterior circulation stroke (TACS). In this paper, we have integrated the advantages of Delaunay triangulation (DT) and fractional order Darwinian particle swarm optimization (FODPSO), called DT-FODPSO technique for automatic segmentation of the structure of the stroke lesion. The approach was validated on 192 MRI images obtained from different stroke subjects. Statistical and morphological features were extracted and classified according to the Oxfordshire community stroke project (OCSP) using support vector machine (SVM) and random forest (RF) classifiers. The method effectively detected the stroke lesions and achieved promising results with an average sensitivity of 0.93, accuracy of 0.95, JI of 0.89 and Dice similarity index of 0.93 using RF classifier. These promising results indicates the DT based optimized approach is efficient in detecting ischemic stroke and it can aid the neuro-radiologists to validate their routine screening.
    Matched MeSH terms: Magnetic Resonance Imaging/methods*
  7. Gan HS, Sayuti KA, Ramlee MH, Lee YS, Wan Mahmud WMH, Abdul Karim AH
    Int J Comput Assist Radiol Surg, 2019 May;14(5):755-762.
    PMID: 30859457 DOI: 10.1007/s11548-019-01936-y
    PURPOSE: Manual segmentation is sensitive to operator bias, while semiautomatic random walks segmentation offers an intuitive approach to understand the user knowledge at the expense of large amount of user input. In this paper, we propose a novel random walks seed auto-generation (SAGE) hybrid model that is robust to interobserver error and intensive user intervention.

    METHODS: Knee image is first oversegmented to produce homogeneous superpixels. Then, a ranking model is developed to rank the superpixels according to their affinities to standard priors, wherein background superpixels would have lower ranking values. Finally, seed labels are generated on the background superpixel using Fuzzy C-Means method.

    RESULTS: SAGE has achieved better interobserver DSCs of 0.94 ± 0.029 and 0.93 ± 0.035 in healthy and OA knee segmentation, respectively. Good segmentation performance has been reported in femoral (Healthy: 0.94 ± 0.036 and OA: 0.93 ± 0.034), tibial (Healthy: 0.91 ± 0.079 and OA: 0.88 ± 0.095) and patellar (Healthy: 0.88 ± 0.10 and OA: 0.84 ± 0.094) cartilage segmentation. Besides, SAGE has demonstrated greater mean readers' time of 80 ± 19 s and 80 ± 27 s in healthy and OA knee segmentation, respectively.

    CONCLUSIONS: SAGE enhances the efficiency of segmentation process and attains satisfactory segmentation performance compared to manual and random walks segmentation. Future works should validate SAGE on progressive image data cohort using OA biomarkers.

    Matched MeSH terms: Magnetic Resonance Imaging/methods*
  8. Hamid K, Yusoff A, Rahman M, Mohamad M, Hamid A
    Biomed Imaging Interv J, 2012 Apr;8(2):e13.
    PMID: 22970069 MyJurnal DOI: 10.2349/biij.8.2.e13
    This fMRI study is about modelling the effective connectivity between Heschl's gyrus (HG) and the superior temporal gyrus (STG) in human primary auditory cortices. MATERIALS #ENTITYSTARTX00026;
    Matched MeSH terms: Magnetic Resonance Imaging
  9. Abd Hamid AI, Yusoff AN, Mukari SZ, Mohamad M
    Malays J Med Sci, 2011 Apr;18(2):3-15.
    PMID: 22135581 MyJurnal
    In spite of extensive research conducted to study how human brain works, little is known about a special function of the brain that stores and manipulates information-the working memory-and how noise influences this special ability. In this study, Functional magnetic resonance imaging (fMRI) was used to investigate brain responses to arithmetic problems solved in noisy and quiet backgrounds.
    Matched MeSH terms: Magnetic Resonance Imaging
  10. Mohamed WN, Abdullah NN, Muda AS
    Malays J Med Sci, 2008 Jul;15(3):55-7.
    PMID: 22570590 MyJurnal
    We report a rare case of Arteriovenous malformation (AVM) of the scalp in a 30 year-old Malay gentleman who presented with painless forehead swelling since birth. Magnetic Resonance Imaging (MRI) and cerebral angiogram performed and the findings are discussed.
    Matched MeSH terms: Magnetic Resonance Imaging
  11. Bhugaloo A, Abdullah B, Siow Y, Ng Kh
    Biomed Imaging Interv J, 2006 Apr;2(2):e12.
    PMID: 21614224 MyJurnal DOI: 10.2349/biij.2.2.e12
    The primary objective of this study was to evaluate the specificity and sensitivity of diffusion weighted MR imaging (DWI) in the differentiation and characterisation between benign and malignant vertebral compression fractures compared with conventional T1 WI, T2 WI and fat suppressed contrast enhanced T1 WI in the Malaysian population.
    Matched MeSH terms: Diffusion Magnetic Resonance Imaging
  12. Zubaidah NH, Liew NC
    Med. J. Malaysia, 2014 Feb;69(1):44-5.
    PMID: 24814632 MyJurnal
    Spontaneous calf haematoma is a rare condition and few case reports have been published in the English literature. Common conditions like deep vein thrombosis and traumatic gastrocnemius muscle tear need to be considered when a patient presents with unilateral calf swelling and tenderness. Ultrasound and Magnetic Resonance Imaging are essential for confirmation of diagnosis. The purpose of this paper is to report on a rare case of spontaneous calf hematoma and its diagnosis and management.
    Matched MeSH terms: Magnetic Resonance Imaging
  13. Dewiputri WI, Auer T
    Malays J Med Sci, 2013 Oct;20(5):5-15.
    PMID: 24643368
    Neurofeedback (NFB) allows subjects to learn how to volitionally influence the neuronal activation in the brain by employing real-time neural activity as feedback. NFB has already been performed with electroencephalography (EEG) since the 1970s. Functional MRI (fMRI), offering a higher spatial resolution, has further increased the spatial specificity. In this paper, we briefly outline the general principles behind NFB, the implementation of fMRI-NFB studies, the feasibility of fMRI-NFB, and the application of NFB as a supplementary therapy tool.
    Matched MeSH terms: Magnetic Resonance Imaging
  14. Low SF, Hanafiah M, Nurismah MI, Suraya A
    BMJ Case Rep, 2013;2013.
    PMID: 24057334 DOI: 10.1136/bcr-2013-200790
    The patella is an uncommon site for all primary and metastatic bone tumours and primary intra-osseous tumours of the patella are very rare. A majority of the patella tumours are benign. We report a patient with a sudden onset swelling and pain of the right knee following a staircase fall. The plain radiograph showed an expansile multiseptated patella lesion and it was further assessed with an MRI. The radiological findings and the initial histopathological features from a limited sample were suggestive of a primary aneurysmal bone cyst. However, the final histopathological diagnosis from a more adequate specimen was a giant cell tumour with a secondary aneurysmal bone cyst.
    Matched MeSH terms: Magnetic Resonance Imaging
  15. Ahmad Nazlim Yusoff
    MyJurnal
    Kajian pengimejan resonans magnet kefungsian (fMRI) subjek tunggal ini menyelidiki kesan daya dan laju tepikan ke atas sifat pengaktifan korteks berkaitan motor semasa tepikan jari rentak sendiri secara bilateral. Subjek melakukan empat cara tepikan jari rentak sendiri iaitu sentuh-perlahan (SP), sentuh-laju (SL), tekan-perlahan (TP) dan tekan-laju (TL) dalam satu imbasan fMRI. Model linear am (GLM) digunakan dalam penjanaan pengaktifan otak. Pentaakulan statistik kemudiannya dibuat mengenai pengaktifan otak menggunakan teori medan rawak (RFT) Gaussian pada aras keertian diperbetulkan (α = 0.05), dengan andaian tiada pengaktifan berlaku. Keputusan mendapati otak mengkoordinasi tepikan jari bilateral rentak sendiri dengan penglibatan korteks berkaitan motor iaitu girus presentral (PCG) bilateral, serebelum bilateral dan juga kawasan motor tambahan (SMA). Peningkatan daya tepikan menonjolkan pengaktifan yang bererti (p < 0.05 diperbetulkan) pada PCG bilateral (Kawasan Brodmann (BA) 6) sejajar dengan fungsinya dalam mencetus tindakan motor seperti mengawal daya tepikan. Peningkatan laju tepikan pula menyebabkan peningkatan pengaktifan otak secara bererti (p < 0.05 diperbetulkan) hanya pada korteks kesatuan somatoderia iaitu pada lobus parietal superior (SPL) kanan atau BA7 kanan. Ini mencadangkan bahawa SPL memainkan peranan penting dalam mengkoordinasi pergerakan berkemahiran terancang.


    Matched MeSH terms: Magnetic Resonance Imaging
  16. Ahmad Nazlim Yusoff, Mohd Harith Hashim, Mohd Mahadir Ayob, Iskandar Kassim
    MyJurnal
    Kajian garis pangkal pengimejan resonans magnet kefungsian (fMRI) telah dijalankan di Jabatan Radiologi, Hospital Universiti Kebangsaan Malaysia ke atas seorang subjek lelaki sihat berumur 25 tahun menggunakan sistem pengimejan resonans magnet (MRI) 1.5 T. Kajian ini menggunakan gerakan jari tangan kanan dan kiri untuk merangsang aktiviti neuron di dalam korteks serebrum. Subjek diarahkan supaya menekan jari-jari pada ibu jari secara bergilir-gilir semasa imbasan kefungsian dilakukan. Paradigma 5 kitar aktifrehat digunakan dengan setiap kitar masing-masing mengandungi 20 siri pengukuran. Keputusan menunjukkan bahawa rantau otak yang aktif akibat gerakan jari adalah girus presentral merangkumi kawasan motor primer. Pengaktifan otak adalah secara kontralateral terhadap gerakan jari tangan kanan dan kiri. Keamatan isyarat keadaan aktif didapati lebih tinggi daripada keamatan isyarat keadaan rehat. Analisis yang dilakukan ke atas beberapa rantau pengaktifan yang diminati (ROI) pada beberapa hirisan menunjukkan perbezaan yang bererti (p < 0.05) antara keamatan keadaan aktif dan rehat untuk nilai ambang statistik (Z) = 1.0 dan 1.5. Perbezaan purata antara kedua-dua purata keamatan isyarat keadaan aktif dan rehat pada manamana hirisan untuk kedua-dua nilai Z menunjukkan magnitud pengaktifan yang lebih tinggi pada hemisfera kanan otak iaitu apabila subjek menggerakkan tangan kirinya. Bilangan voksel yang aktif juga didapati lebih tinggi pada hemisfera kanan berbanding pada hemisfera kiri otak. Keputusan ini menyokong fakta bahawa bagi subjek yang tidak kidal, kawasan pengaktifan motor pada hemisfera kanan otak semasa gerakan jari tangan kiri mengalami rangsangan hemodinamik yang lebih tinggi berbanding dengan hemisfera kiri otak semasa gerakan jari tangan kanan. Fenomena rangsangan hemodinamik yang diperhatikan dalam kajian ini dibincangkan berdasarkan kepada kebergantungan kontras isyarat kepada aras oksigen darah (BOLD).
    Matched MeSH terms: Magnetic Resonance Imaging
  17. Ahmad Nazlim Yusoff, Mohd Harith Hashim, Mohd Mahadir Ayob, Iskandar Kassim
    MyJurnal
    Kajian garis pangkal pengimejan resonans magnet kefungsian (fMRI) telah dijalankan ke atas 2 orang subjek lelaki sihat (kidal dan tidak kidal) masing-masing berumur 22 dan 25 tahun. Imbasan fMRI dijalankan menggunakan sistem pengimejan resonans magnet (MRI) 1.5 T di Jabatan Radiologi, Hospital Universiti Kebangsaan Malaysia. Kajian ini menggunakan gerakanjari tangan kanan dan kiri untuk merangsang aktiviti neuron di dalam korteks serebrum. Paradigma 5 kitar aktifIrehat digunakan dengan setiap kitar mengandungi satu blok aktif dan satu blok rehat yang masing-masing mengandungi 10 siri pengukuran. Imej fMRI dianalisis menggunakan pekej perisian MatLab dan pemetaan statistik berparameter 2 (sPM2). Proses pendaftaran jasad tegar menggunakan penjelmaan afin 6 parameter dilakukan ke atas kesemua imej kefungsian berwajaran T2*. Keputusan menunjukkan bahawa pergerakan subjek adalah minimum sama ada dalam arah translasi (< 1 mm) atau putaran (< 1 ). Kesemua imej dinormalkan melalui proses peledingan tak linear menggunakan penjelmaan afin 12 parameter dan didapati sepadan dengan pencontoh yang telahpun mematuhi ruang anatomi piawai. Walau bagaimanapun, bentuk, resolusi dan kontras imej kefungsian telah berubah sedikit berbanding dengan imej asal. Pelicinan imej menggunakan kernel Gaussian isotropik 6 mm menyebabkan data imej lebih bersifat parametrik dengan kehilangan yang ketara dalam resolusi dan kontras. Pengasingan struktur yang dilakukan ke atas imej berwajaran T1 mengklaskan tisu otak kepadajirim kelabu, jirim putih dan bendalir serebrospina. Pasca pemprosesan ruang bagi imej kefungsian dan struktur menjadikan data imej bersifat parametrik dengan taburan jenis Gaussian dan sedia untuk dianalisis menggunakan model linear am dan teori medan rawak Gaussian.
    Matched MeSH terms: Magnetic Resonance Imaging
  18. Ahmad, N. Z., Aini Ismafairus, A. H., Khairiah, A. H., Wan Ahmad Kamil, W. A., Mazlyfarina, M., Hanani, A. M.
    MyJurnal
    Introduction: This multiple-subject fMRI study continue to further investigate brain activation within and effective connectivity between the significantly (p
    Matched MeSH terms: Magnetic Resonance Imaging
  19. Ee, G.C.L., Jong, V.Y.M., Sukari, M.A., Rahmani, M., Kua, A.S.M.
    MyJurnal
    The roots of Calophyllum inophyllum (Guttiferae), furnished six xanthones which are brasilixanthone (1), 1,3,5-trihydroxy-2- methoxy xanthone (2), caloxanthone A (3), pyranojacareubin (4), caloxanthone B (5) and tovopyrifolin (6), Structural elucidations of these compounds, were achieved through 1D and 2D NMR andMS techniques. In this paper, the isolation and structural elucidation data for these xanthones are reported.
    Matched MeSH terms: Magnetic Resonance Imaging
  20. A.N. Yusoff
    Sains Malaysiana, 2013;42:765-771.
    Kajian pengimejan resonans magnet kefungsian (fMRI) subjek tunggal ini menyelidiki interaksi psikofisiologi (PPI) antara girus presentral (PCG) dan lobus parietal superior (SPL) kanan semasa tepikan jari rentak sendiri secara bilateral. Model kehubungan efektif antara PCG dan SPL kanan dibina menggunakan analisis PPI dengan mengambil daya dan laju tepikan sebagai faktor uji kaji. Keputusan menunjukkan bahawa peningkatan daya dan laju tepikan masing-masing mengaktifkan PCG bilateral dan SPL kanan secara bererti (p<0.05). PCG dan SPL kanan didapati saling berhubungan semasa tepikan jari dilakukan dengan daya dan laju tepikan sebagai faktor uji kaji yang mempengaruhi kehubungan efektif antara mereka. Kajian ini telah mendedahkan maklumat asas berguna untuk kajian fMRI pada masa depan ke atas koordinasi motor dan boleh digunakan untuk mengkaji ketaktertiban otak misalnya strok.
    Matched MeSH terms: Magnetic Resonance Imaging
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