Displaying publications 281 - 300 of 1057 in total

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  1. Ng GYH, Nah SA, Teoh OH, Ong LY
    Pediatr Surg Int, 2020 Mar;36(3):383-389.
    PMID: 31993738 DOI: 10.1007/s00383-020-04619-x
    BACKGROUND: The risk factors for recurrence in primary spontaneous pneumothorax (PSP) in children are not well known. We aimed to identify possible risk factors, and to evaluate the utility of computerised tomography (CT) scans in predicting future episodes.

    METHODS: We reviewed children aged 

    Matched MeSH terms: Tomography, X-Ray Computed/methods*
  2. Rais NNM, Bradley DA, Hashim A, Isa NM, Osman ND, Ismail I, et al.
    J Radiol Prot, 2019 Sep;39(3):N8-N18.
    PMID: 31018196 DOI: 10.1088/1361-6498/ab1c16
    Novel germanium (Ge)-doped silica glass fibres tailor-made in Malaysia are fast gaining recognition as potential media for thermoluminescence (TL) dosimetry, with active research ongoing into exploitation of their various beneficial characteristics. Investigation is made herein of the capability of these media for use in diagnostic imaging dosimetry, specifically at the radiation dose levels typically obtained in conduct of Computed Tomography (CT). As a first step within such efforts, there is need to investigate the performance of the fibres using tightly defined spectra, use being made of a Philips constant potential industrial x-ray facility, Model MG165, located at the Malaysian Nuclear Agency Secondary Standards Dosimetry Lab (SSDL). Standard radiation beam qualities (termed RQT) have been established for CT, in accord with IEC 61267: 2003 and IAEA Technical Reports Series No. 457: 2007. A calibrated ionisation chamber has also been utilised, forming a component part of the SSDL equipment. The fabricated fibres used in this study are 2.3 mol% flat fibre (FF) of dimensions 643 × 356 μm2 and 2.3 mol% cylindrical fibre (CF) of 481 μm diameter, while the commercial fibre used is 4 mol% with core diameter of 50 μm. The dopant concentrations are nominal preform values. The fibres have been irradiated to doses of 20, 30 and 40 milligray (mGy) for each of the beam qualities RQT 8, RQT 9 and RQT 10. For x-rays generated at constant potential values from 100 to 150 kV, a discernible energy-dependent response is seen, comparisons being made with that of lithium fluoride (LiF) thermoluminescence dosimeters (TLD-100). TL yield versus dose has also been investigated for x-ray doses from 2 to 40 mGy, all exhibiting linearity. Compared to TLD-100, greater sensitivity is observed for the fibres.
    Matched MeSH terms: Tomography, X-Ray Computed*
  3. Abdullah JY, Rajion ZA, Martin AG, Jaafar A, Ghani ARI, Abdullah JM
    Neurocirugia (Astur : Engl Ed), 2019 02 16;30(3):115-123.
    PMID: 30782505 DOI: 10.1016/j.neucir.2018.12.004
    INTRODUCTION: Intracranial volume (ICV) is an important tool in the management of patients undergoing decompressive craniectomy (DC) surgery. The aim of this study was to validate ICV measurement applying the shape-based interpolation (SBI) method using open source software on computed tomography (CT) images.

    METHODS: The pre- and post-operative CT images of 55 patients undergoing DC surgery were analyzed. The ICV was measured by segmenting every slice of the CT images, and compared with estimated ICV calculated using the 1-in-10 sampling strategy and processed using the SBI method. An independent t test was conducted to compare the ICV measurements between the two different methods. The calculation using this method was repeated three times for reliability analysis using the intraclass correlations coefficient (ICC). The Bland-Altman plot was used to measure agreement between the methods for both pre- and post-operative ICV measurements.

    RESULTS: The mean ICV (±SD) were 1341.1±122.1ml (manual) and 1344.11±122.6ml (SBI) for the preoperative CT data. The mean ICV (±SD) were 1396.4±132.4ml (manual) and 1400.53±132.1ml (SBI) for the post-operative CT data. No significant difference was found in ICV measurements using the manual and the SBI methods (p=.983 for pre-op, and p=.960 for post-op). The intrarater ICC showed a significant correlation; ICC=1.00. The Bland-Altman plot showed good agreement between the manual and the SBI method.

    CONCLUSION: The shape-based interpolation method with 1-in-10 sampling strategy gave comparable results in estimating ICV compared to manual segmentation. Thus, this method could be used in clinical settings for rapid, reliable and repeatable ICV estimations.

    Matched MeSH terms: Tomography, X-Ray Computed*
  4. Lee YJ, Zakaria R, Manaf ZA, Mohamed Z, Lee YY
    Chin Med J (Engl), 2013;126(11):2049-53.
    PMID: 23769556
    There is increasing evidence that CT pulmonary arteriography and venography allow a better diagnostic yield for deep vein thrombosis (DVT) in suspected acute pulmonary embolism (PE). The aim was to investigate the value for using such an approach in a multiracial Asian population.
    Matched MeSH terms: Tomography, X-Ray Computed/methods*
  5. Abdullah KA, McEntee MF, Reed WM, Kench PL
    J Appl Clin Med Phys, 2020 Sep;21(9):209-214.
    PMID: 32657493 DOI: 10.1002/acm2.12977
    PURPOSE: The purpose of this study was to investigate the effect of increasing iterative reconstruction (IR) algorithm strength at different tube voltages in coronary computed tomography angiography (CCTA) protocols using a three-dimensional (3D)-printed and Catphan® 500 phantoms.

    METHODS: A 3D-printed cardiac insert and Catphan 500 phantoms were scanned using CCTA protocols at 120 and 100 kVp tube voltages. All CT acquisitions were reconstructed using filtered back projection (FBP) and Adaptive Statistical Iterative Reconstruction (ASIR) algorithm at 40% and 60% strengths. Image quality characteristics such as image noise, signal-noise ratio (SNR), contrast-noise ratio (CNR), high spatial resolution, and low contrast resolution were analyzed.

    RESULTS: There was no significant difference (P > 0.05) between 120 and 100 kVp measures for image noise for FBP vs ASIR 60% (16.6 ± 3.8 vs 16.7 ± 4.8), SNR of ASIR 40% vs ASIR 60% (27.3 ± 5.4 vs 26.4 ± 4.8), and CNR of FBP vs ASIR 40% (31.3 ± 3.9 vs 30.1 ± 4.3), respectively. Based on the Modulation Transfer Function (MTF) analysis, there was a minimal change of image quality for each tube voltage but increases when higher strengths of ASIR were used. The best measure of low contrast detectability was observed at ASIR 60% at 120 kVp.

    CONCLUSIONS: Changing the IR strength has yielded different image quality noise characteristics. In this study, the use of 100 kVp and ASIR 60% yielded comparable image quality noise characteristics to the standard CCTA protocols using 120 kVp of ASIR 40%. A combination of 3D-printed and Catphan® 500 phantoms could be used to perform CT dose optimization protocols.

    Matched MeSH terms: Tomography, X-Ray Computed*
  6. Sim CY, Khoo CS, Mustafar R, Chai JN
    Balkan Med J, 2021 01;38(1):55-56.
    PMID: 32720494 DOI: 10.4274/balkanmedj.galenos.2020.2020.5.208
    Matched MeSH terms: Tomography, X-Ray Computed/methods
  7. Abdul Hadi D, Mansharan Kaur CS, Effat O, Siew SF
    Trop Biomed, 2019 Dec 01;36(4):850-854.
    PMID: 33597457
    Tuberculosis (TB) is a highly infectious disease on the rise caused by the organism Mycobacterium tuberculosis and health care workers working in emergency departments, medical wards and autopsy rooms are in danger of contacting this disease. We present a case of a 42 year old man found dead under a pedestrian bridge with no medical history available. Post mortem computed tomography showed multiple cavities involving upper lobes of both lungs and areas of consolidation in both lung fields raising the suspicion of pulmonary tuberculosis. This was followed by a computed tomography guided lung biopsy and a limited conventional autopsy done in situ in a special high risk autopsy suite with appropriate ventilation. This case highlights the importance of cross sectional imaging which can be coupled with image guided biopsy in cases of infectious disease to reduce the risk of transmission to health care workers.
    Matched MeSH terms: Tomography, X-Ray Computed*
  8. Sahdi H, Hoong CW, Rasit AH, Arianto F, Siong LK, Abdullah NA
    J Orthop Surg (Hong Kong), 2017 01;25(1):2309499016684989.
    PMID: 28166702 DOI: 10.1177/2309499016684989
    Diplopodia, being a rare congenital disorder, is infrequently discussed in published texts. Most reported cases have accounted the involvement of duplicated preaxial digits with other associated organ system and physical deformities. Here, we present an unusual case of isolated diplopodia involving postaxial toes in a child with no other organ and physical abnormalities. Radiological studies revealed a set of 10-digit-duplicated foot over the lateral aspect of the native foot, complete with phalanges and its corresponding metatarsals as well as tarsals, supplied by an anomalous posterior branch of the popliteal artery. Definitive surgery was performed just before the child was learning to walk.
    Matched MeSH terms: Tomography, X-Ray Computed/methods*
  9. Jalalian A, Mashohor S, Mahmud R, Karasfi B, Iqbal Saripan M, Ramli AR
    J Digit Imaging, 2017 Dec;30(6):796-811.
    PMID: 28429195 DOI: 10.1007/s10278-017-9958-5
    Computed tomography laser mammography (Eid et al. Egyp J Radiol Nucl Med, 37(1): p. 633-643, 1) is a non-invasive imaging modality for breast cancer diagnosis, which is time-consuming and challenging for the radiologist to interpret the images. Some issues have increased the missed diagnosis of radiologists in visual manner assessment in CTLM images, such as technical reasons which are related to imaging quality and human error due to the structural complexity in appearance. The purpose of this study is to develop a computer-aided diagnosis framework to enhance the performance of radiologist in the interpretation of CTLM images. The proposed CAD system contains three main stages including segmentation of volume of interest (VOI), feature extraction and classification. A 3D Fuzzy segmentation technique has been implemented to extract the VOI. The shape and texture of angiogenesis in CTLM images are significant characteristics to differentiate malignancy or benign lesions. The 3D compactness features and 3D Grey Level Co-occurrence matrix (GLCM) have been extracted from VOIs. Multilayer perceptron neural network (MLPNN) pattern recognition has developed for classification of the normal and abnormal lesion in CTLM images. The performance of the proposed CAD system has been measured with different metrics including accuracy, sensitivity, and specificity and area under receiver operative characteristics (AROC), which are 95.2, 92.4, 98.1, and 0.98%, respectively.
    Matched MeSH terms: Tomography, X-Ray Computed/methods*
  10. Hamizan AW, Loftus PA, Alvarado R, Ho J, Kalish L, Sacks R, et al.
    Laryngoscope, 2018 09;128(9):2015-2021.
    PMID: 29602169 DOI: 10.1002/lary.27180
    OBJECTIVES/HYPOTHESIS: Polypoid edema of the middle turbinate is a marker of inhalant allergy. Extensive edematous changes may result in limited central nasal and sinus disease, which has been called central compartment atopic disease (CCAD). Radiologically, this is seen as soft tissue thickening in the central portion of the sinonasal cavity with or without paranasal sinus involvement. When the sinuses are involved, the soft tissue thickening spares the sinus roof or lateral wall (centrally limited). This centrally limited radiological pattern was assessed among chronic rhinosinusitis (CRS) patients and compared to allergy status.

    STUDY DESIGN: Diagnostic cross-sectional study.

    METHODS: This study included consecutive CRS patients without prior sinus surgery. Computed tomography (CT) scans of the paranasal sinuses were blindly assessed and allergy status was confirmed by serum or skin testing. Individual sinus cavities were defined as either centrally limited or diffuse disease. The radiological pattern that may predict allergy was determined, and its diagnostic accuracy was calculated.

    RESULTS: One hundred twelve patients diagnosed to have CRS, representing 224 sides, were assessed (age 46.31 ± 13.57 years, 38.39% female, 41.07% asthma, Lund-Mackay CT score 15.88 ± 4.35, 56.25% atopic). The radiological pattern defined by centrally limited changes in all of the paranasal sinuses was associated with allergy status (73.53% vs. 53.16%, P = .03). This predicted atopy with 90.82% specificity, 73.53% positive predictive value, likelihood positive ratios of 2.16, and diagnostic odds ratio of 4.59.

    CONCLUSIONS: A central radiological pattern of mucosal disease is associated with inhalant allergen sensitization. This group may represent a CCAD subgroup of patients with mainly allergic etiology.

    LEVEL OF EVIDENCE: 3b Laryngoscope, 128:2015-2021, 2018.

    Matched MeSH terms: Tomography, X-Ray Computed/statistics & numerical data*
  11. Kho SS, Yong MC, Chan SK, Tie ST
    Thorax, 2018 10;73(10):994-995.
    PMID: 29599199 DOI: 10.1136/thoraxjnl-2018-211729
    Matched MeSH terms: Tomography, X-Ray Computed/methods
  12. Shivdas S, Hashim MS, Ahmad TS
    J Orthop Surg (Hong Kong), 2018 10 4;26(3):2309499018802504.
    PMID: 30278809 DOI: 10.1177/2309499018802504
    PURPOSE: Our primary objectives were to create a reliable, noninvasive method for three-dimensional morphometry of deep bony parameters within the sigmoid notch of the distal radius, to identify its morphological patterns, and to identify any significant variation between the left and the right wrists. Our secondary objectives were to obtain morphometric values that could represent our population and to identify any possible ethnic variations.

    METHODS: Computed tomography scans of 102 wrists from 51 healthy individuals were analyzed using a virtualization software. Four anatomical parameters at the distal radius sigmoid notch, namely, the radius of curvature, depth, version angle, and sagittal slope were measured. Morphological patterns of the sigmoid notch surface were identified. The results were statistically analyzed to assess the reliability of the technique and were compared with previously published literature.

    RESULTS: Comparing our findings with previously published values, our study revealed a slightly larger radius of curvature and sagittal slope, while revealing a smaller depth and version. We identified the S-type, C-type, and ski-slope morphological variants. The flat-face morphological variant, however, was not identified. The sigmoid notch at the left and right wrists were similar, except for the radius of curvature.

    CONCLUSION: This study demonstrates a noninvasive, fast, reliable, and reproducible technique for analyzing the sigmoid notch of the distal radius. In wrist injuries with intact distal radius sigmoid notch but involving comminuted fractures of the ulnar head, ulnar head replacement may be indicated. In such cases, analysis of the ipsilateral intact sigmoid notch would allow us to prepare an ulnar head prosthesis of appropriate size.

    Matched MeSH terms: Tomography, X-Ray Computed*
  13. Khan SU, Ullah N, Ahmed I, Ahmad I, Mahsud MI
    Curr Med Imaging Rev, 2019;15(3):243-254.
    PMID: 31989876 DOI: 10.2174/1573405614666180726124952
    BACKGROUND: Medical imaging is to assume greater and greater significance in an efficient and precise diagnosis process.

    DISCUSSION: It is a set of various methodologies which are used to capture internal or external images of the human body and organs for clinical and diagnosis needs to examine human form for various kind of ailments. Computationally intelligent machine learning techniques and their application in medical imaging can play a significant role in expediting the diagnosis process and making it more precise.

    CONCLUSION: This review presents an up-to-date coverage about research topics which include recent literature in the areas of MRI imaging, comparison with other modalities, noise in MRI and machine learning techniques to remove the noise.

    Matched MeSH terms: Tomography, X-Ray Computed/methods
  14. Khoo CS, Kim SE, Lee BI, Shin KJ, Ha SY, Park J, et al.
    Eur Neurol, 2020;83(1):56-64.
    PMID: 32320976 DOI: 10.1159/000506591
    INTRODUCTION: Seizures as acute stroke mimics are a diagnostic challenge.

    OBJECTIVE: The aim of the study was to characterize the perfusion patterns on perfusion computed tomography (PCT) in patients with seizures masquerading as acute stroke.

    METHODS: We conducted a study on patients with acute seizures as stroke mimics. The inclusion criteria for this study were patients (1) initially presenting with stroke-like symptoms but finally diagnosed to have seizures and (2) with PCT performed within 72 h of seizures. The PCT of seizure patients (n = 27) was compared with that of revascularized stroke patients (n = 20) as the control group.

    RESULTS: Among the 27 patients with seizures as stroke mimics, 70.4% (n = 19) showed characteristic PCT findings compared with the revascularized stroke patients, which were as follows: (1) multi-territorial cortical hyperperfusion {(73.7% [14/19] vs. 0% [0/20], p = 0.002), sensitivity of 73.7%, negative predictive value (NPV) of 80%}, (2) involvement of the ipsilateral thalamus {(57.9% [11/19] vs. 0% [0/20], p = 0.007), sensitivity of 57.9%, NPV of 71.4%}, and (3) reduced perfusion time {(84.2% [16/19] vs. 0% [0/20], p = 0.001), sensitivity of 84.2%, NPV of 87%}. These 3 findings had 100% specificity and positive predictive value in predicting patients with acute seizures in comparison with reperfused stroke patients. Older age was strongly associated with abnormal perfusion changes (p = 0.038), with a mean age of 66.8 ± 14.5 years versus 49.2 ± 27.4 years (in seizure patients with normal perfusion scan).

    CONCLUSIONS: PCT is a reliable tool to differentiate acute seizures from acute stroke in the emergency setting.

    Matched MeSH terms: Tomography, X-Ray Computed/methods*
  15. Isa INC, Rahmat SMS, Dom SM, Kayun Z, Karim MKA
    J Xray Sci Technol, 2019;27(4):631-639.
    PMID: 31205011 DOI: 10.3233/XST-190491
    There are several factors that may contribute to the increase in radiation dose of CT including the use of unoptimized protocols and improper scanning technique. In this study, we aim to determine significant impact on radiation dose as a result of mis-centering during CT head examination. The scanning was performed by using Toshiba Aquilion 64 slices multi-detector CT (MDCT) scanner and dose were measured by using calibrated ionization chamber. Two scanning protocols of routine CT head; 120 kVp/ 180 mAs and 100 kVp/ 142 mAs were used represent standard and low dose, respectively. As reference measurement, the dose was first measured on standard cylindrical polymethyl methacrylate (PMMA) phantom that positioned at 104 cm from the floor (reference isocenter). The positions then were varied to simulate mis-centering by 5 cm from isocenter, superiorly and inferiorly at 109 cm, 114 cm, 119 cm, 124 cm and 99 cm, 94 cm, 89 cm, 84 cm, respectively. Scanning parameter and dose information from the console were recorded for the radiation effective dose (E) measurement. The highest mean CTDIvol value for MCS and MCI were 105.06 mGy (at +10 cm) and 105.51 mGy (at - 10 cm), respectively which differed significantly (p 
    Matched MeSH terms: Tomography, X-Ray Computed/standards*
  16. Loong S, Selvarajan S, Khor LY
    Malays J Pathol, 2019 Dec;41(3):327-331.
    PMID: 31901917
    INTRODUCTION: The increasing use of radiological imaging studies has given rise to 'incidentalomas'.

    CASE REPORT: We describe two unusual and diverse incidental adrenal gland lesions, an adenomatoid nodule and a mature ganglioneuroma. Both are deemed 'indeterminate' on radiological assessment. On histology, an adenomatoid nodule is composed of variably-dilated thin-walled cysts lined by bland flattened cells and solid areas of tubules lined by eosinophilic cells with plump nuclei and prominent nucleoli. The lining cells are immunoreactive for calretinin and WT1 while negative for CK5/6, ERG and CD31. Mature ganglioneuroma features fascicles of bland spindle cells with intermixed mature ganglion cells disposed within a background myxoid stroma with no immature neuroblastic component. These spindled Schwann cells are S100 positive.

    DISCUSSION: Both adenomatoid nodule and mature ganglioneuroma are rare benign adrenal tumours that need to be differentiated from other, more common adrenal lesions. The management of adrenal incidentalomas is challenging. Surgical excision is indicated if an adrenal incidentaloma is more than 4 cm in size, shows malignant features on imaging or evidence of hormone excess.

    Matched MeSH terms: Tomography, X-Ray Computed/methods
  17. Cheah PK, Krisnan T, Abdul Kadir MH, Steven EM
    Emerg Med J, 2020 Aug;37(8):467.
    PMID: 32546476 DOI: 10.1136/emermed-2020-209851
    Matched MeSH terms: Tomography, X-Ray Computed/methods*
  18. Abbasian Ardakani A, Acharya UR, Habibollahi S, Mohammadi A
    Eur Radiol, 2021 Jan;31(1):121-130.
    PMID: 32740817 DOI: 10.1007/s00330-020-07087-y
    OBJECTIVES: CT findings of COVID-19 look similar to other atypical and viral (non-COVID-19) pneumonia diseases. This study proposes a clinical computer-aided diagnosis (CAD) system using CT features to automatically discriminate COVID-19 from non-COVID-19 pneumonia patients.

    METHODS: Overall, 612 patients (306 COVID-19 and 306 non-COVID-19 pneumonia) were recruited. Twenty radiological features were extracted from CT images to evaluate the pattern, location, and distribution of lesions of patients in both groups. All significant CT features were fed in five classifiers namely decision tree, K-nearest neighbor, naïve Bayes, support vector machine, and ensemble to evaluate the best performing CAD system in classifying COVID-19 and non-COVID-19 cases.

    RESULTS: Location and distribution pattern of involvement, number of the lesion, ground-glass opacity (GGO) and crazy-paving, consolidation, reticular, bronchial wall thickening, nodule, air bronchogram, cavity, pleural effusion, pleural thickening, and lymphadenopathy are the significant features to classify COVID-19 from non-COVID-19 groups. Our proposed CAD system obtained the sensitivity, specificity, and accuracy of 0.965, 93.54%, 90.32%, and 91.94%, respectively, using ensemble (COVIDiag) classifier.

    CONCLUSIONS: This study proposed a COVIDiag model obtained promising results using CT radiological routine features. It can be considered an adjunct tool by the radiologists during the current COVID-19 pandemic to make an accurate diagnosis.

    KEY POINTS: • Location and distribution of involvement, number of lesions, GGO and crazy-paving, consolidation, reticular, bronchial wall thickening, nodule, air bronchogram, cavity, pleural effusion, pleural thickening, and lymphadenopathy are the significant features between COVID-19 from non-COVID-19 groups. • The proposed CAD system, COVIDiag, could diagnose COVID-19 pneumonia cases with an AUC of 0.965 (sensitivity = 93.54%; specificity = 90.32%; and accuracy = 91.94%). • The AUC, sensitivity, specificity, and accuracy obtained by radiologist diagnosis are 0.879, 87.10%, 88.71%, and 87.90%, respectively.

    Matched MeSH terms: Tomography, X-Ray Computed*
  19. Annuar BR, Liew CK, Chin SP, Ong TK, Seyfarth MT, Chan WL, et al.
    Eur J Radiol, 2008 Jan;65(1):112-9.
    PMID: 17466480
    To compare the assessment of global and regional left ventricular (LV) function using 64-slice multislice computed tomography (MSCT), 2D echocardiography (2DE) and cardiac magnetic resonance (CMR).
    Matched MeSH terms: Tomography, X-Ray Computed/methods*
  20. Khajotia RR, Raman S
    Aust Fam Physician, 2017 Nov;46(11):845-846.
    PMID: 29101921
    Matched MeSH terms: Tomography, X-Ray Computed/methods*
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