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  1. Fulltext Multislice CT angiography in cardiac imaging: prospective ECG-gating or retrospective ECG-gating?
    Sun Z
    Biomed Imaging Interv J, 2010 01 01;6(1):e4.
    PMID: 21611064 DOI: 10.2349/biij.6.1.e4
    With the advent of multislice CT more than a decade ago, multislice CT angiography has demonstrated a huge potential in the less invasive imaging of cardiovascular disease, especially in the diagnosis of coronary artery disease. The diagnostic accuracy of multislice CT angiography has been significantly augmented with the rapid technical developments ranging from the initial 4-slice, to the current 64-slice and 256 and 320-slice CT scanners. This is mainly demonstrated by the improved spatial and temporal resolution when compared to the earlier type of CT scanners. Traditionally, multislice CT angiography is acquired with retrospective ECG-gating with acquisition of volume data at the expense of increased radiation dose, since data is acquired at the entire cardiac cycle, although not all of them are used for postprocessing or reconstructions. Recently, there is an increasing trend of utilising prospective ECG-gating in cardiac imaging with latest multislice CT scanners (64 or more slices) with significant reduction of radiation dose when compared to retrospective ECG-gating method. However, there is some debate as to the diagnostic value of prospective ECG-gating in the diagnosis of coronary artery disease, despite its attractive ability to reduce radiation dose. This article will review the performance of retrospective ECG-gating in the diagnostic value of coronary artery disease, highlight the potential applications of prospective ECG-gating, and explore the future directions of multislice CT angiography in cardiac imaging.
  2. Fulltext Coronary CT angiography: Dose reduction strategies
    Sabarudin A, Sun Z
    World J Cardiol, 2013 Dec 26;5(12):465-72.
    PMID: 24392191 DOI: 10.4330/wjc.v5.i12.465
    With the introduction of 64- and post-64 slice computed tomography (CT) technology, coronary CT angiography has been increasingly used as a less invasive modality for the diagnosis of coronary artery disease. Despite its high diagnostic value and promising results compared to invasive coronary angiography, coronary CT angiography is associated with high radiation dose, leading to potential risk of radiation-induced cancer. A variety of dose-reduction strategies have been reported recently to reduce radiation dose with effective outcomes having been achieved. This article presents an overview of the various methods currently used for radiation dose reduction.
  3. Fulltext Radiation dose measurements in coronary CT angiography
    Sabarudin A, Sun Z
    World J Cardiol, 2013 Dec 26;5(12):459-64.
    PMID: 24392190 DOI: 10.4330/wjc.v5.i12.459
    Coronary computed tomography (CT) angiography is associated with high radiation dose and this has raised serious concerns in the literature. Awareness of various parameters for dose estimates and measurements of coronary CT angiography plays an important role in increasing our understanding of the radiation exposure to patients, thus, contributing to the implementation of dose-saving strategies. This article provides an overview of the radiation dose quantity and its measurement during coronary CT angiography procedures.
  4. Fulltext Beta-blocker administration protocol for prospectively ECG-triggered coronary CT angiography
    Sabarudin A, Sun Z
    World J Cardiol, 2013 Dec 26;5(12):453-8.
    PMID: 24392189 DOI: 10.4330/wjc.v5.i12.453
    The aim of this article is to discuss the protocol of beta-blockers that is commonly used for prospectively ECG-triggered coronary computed tomography angiography (CCTA). It is essential to ensure a low and regular heart rate in patients undergoing prospectively ECG-triggered CCTA for optimal visualization of coronary arteries. Although early generations of computed tomographyscanners are not applicable to be tailored according to patients' heart rate, a low and regular heart rate is possible to be achieved by the administration of medications according to the beta-blocker protocol. Beta-blocker can be safely administered to reduce patients' heart rate for CCTA examination if patients are screened for certain contraindications.
  5. Fulltext Coronary CT angiography: Diagnostic value and clinical challenges
    Sabarudin A, Sun Z
    World J Cardiol, 2013 Dec 26;5(12):473-83.
    PMID: 24392192 DOI: 10.4330/wjc.v5.i12.473
    Coronary computed tomography (CT) angiography has been increasingly used in the diagnosis of coronary artery disease due to improved spatial and temporal resolution with high diagnostic value being reported when compared to invasive coronary angiography. Diagnostic performance of coronary CT angiography has been significantly improved with the technological developments in multislice CT scanners from the early generation of 4-slice CT to the latest 320- slice CT scanners. Despite the promising diagnostic value, coronary CT angiography is still limited in some areas, such as inferior temporal resolution, motion-related artifacts and high false positive results due to severe calcification. The aim of this review is to present an overview of the technical developments of multislice CT and diagnostic value of coronary CT angiography in coronary artery disease based on different generations of multislice CT scanners. Prognostic value of coronary CT angiography in coronary artery disease is also discussed, while limitations and challenges of coronary CT angiography are highlighted.
  6. Radiation dose in coronary CT angiography associated with prospective ECG-triggering technique: comparisons with different CT generations
    Sabarudin A, Sun Z, Ng KH
    Radiat Prot Dosimetry, 2013;154(3):301-7.
    PMID: 22972797 DOI: 10.1093/rpd/ncs243
    A retrospective analysis was performed in patients undergoing prospective ECG-triggered coronary computed tomography (CT) angiography (CCTA) with the single-source 64-slice CT (SSCT), dual-source 64-slice CT (DSCT), dual-source 128-slice CT and 320-slice CT with the aim of comparing the radiation dose associated with different CT generations. A total of 164 patients undergoing prospective ECG-triggered CCTA with different types of CT scanners were studied with the mean effective doses estimated at 6.8 ± 3.2, 4.2 ± 1.9, 4.1±0.6 and 3.8 ± 1.4 mSv corresponding to the 128-slice DSCT, 64-slice DSCT, 64-slice SSCT and 320-slice CT scanners. In this study a positive relationship was found between the effective dose and the body mass index (BMI). A low radiation dose is achieved in prospective ECG-triggered CCTA, regardless of the CT scanner generation. BMI is identified as the major factor that has a direct impact on the effective dose associated with prospective ECG-triggered CCTA.
  7. Coronary CT angiography with single-source and dual-source CT: comparison of image quality and radiation dose between prospective ECG-triggered and retrospective ECG-gated protocols
    Sabarudin A, Sun Z, Yusof AK
    Int J Cardiol, 2013 Sep 30;168(2):746-53.
    PMID: 23098849 DOI: 10.1016/j.ijcard.2012.09.217
    This study is conducted to investigate and compare image quality and radiation dose between prospective ECG-triggered and retrospective ECG-gated coronary CT angiography (CCTA) with the use of single-source CT (SSCT) and dual-source CT (DSCT).
  8. Fulltext Cerebral CT angiography and CT perfusion in acute stroke detection: a systematic review of diagnostic value
    Sabarudin A, Subramaniam C, Sun Z
    Quant Imaging Med Surg, 2014 Aug;4(4):282-90.
    PMID: 25202664 DOI: 10.3978/j.issn.2223-4292.2014.07.10
    The purpose of this study was to analyse the diagnostic value of cerebral CT angiography (CTA) and CT perfusion (CTP) examinations in the detection of acute stroke based on a systematic review of the current literature. The review was conducted based on searching of seven databases for articles published between 1993 and 2013. Diagnostic value in terms of sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy was analysed from 21 articles which were found to meet selection criteria. The mean sensitivity, specificity, PPV, NPV and accuracy for CTA were significantly higher than those for CTP with 83.2% (95% CI: 57.9-100.0%), 95.0% (95% CI: 74.4-100%), 84.1% (95% CI: 50.0-100%), 97.1 (95% CI: 94.0-100%) and 94.0% (95% CI: 83.0-99.0) versus 69.9% (95% CI: 20.0-97.0%), 87.4 (95% CI: 61.0-100.0%), 76.4% (95% CI: 48.0-95.4%), 78.2% (95% CI: 55.8-93.9%) and 89.8% (95% CI: 75.7-97.1%), respectively. This analysis shows that CTA has high diagnostic value in detecting high degree of cerebral arterial stenosis (>70%) whereas CTP provides high specificity in the detection of ischemia and infarct tissue of brain.
  9. Fulltext Factors in consumers' purchase intention for Gejia batik
    Li X, Romainoor NH, Sun Z
    Heliyon, 2024 Jan 15;10(1):e23085.
    PMID: 38163224 DOI: 10.1016/j.heliyon.2023.e23085
    In China's vigorous development and inheritance of intangible cultural heritage, the sustainability and acceptability of intangible cultural heritage products have become a controversial subject. This study aims to explore the relationship between batik product qualia factors and the purchase intention for batik products and exammine the mediating role of consumer attitude in the relationship. We adopted quantitative research methods and used SPSS 26 and Process 2.15 software to test our hypotheses. We conducted extensive surveys of consumers of different ages, genders, income levels, and educational backgrounds, and finally, a total of 381 valid questionnaires were collected. The results showed that batik products' creativity, delicacy, beauty, and eco-friendliness were significantly and positively related to consumers' attitudes. In addition, creativity, beauty, and eco-friendliness, but not delicacy, were significantly and positively associated with consumers' purchase intention. Consumer attitude plays an intermediary role between qualia factors and purchase intention. This study analyzes Gejia batik from the perspective of qualia factors, breaking through the limitations of previous studies on the aspects of heritage protection and environmental protection. The study's results can inspire batik manufacturers or designers to enhance the competitiveness of batik design products in the tourism market.
  10. Radiation dose associated with cerebral CT angiography and CT perfusion: an experimental phantom study
    Sabarudin A, Yusof MZ, Mohamad M, Sun Z
    Radiat Prot Dosimetry, 2014 Dec;162(3):316-21.
    PMID: 24255172 DOI: 10.1093/rpd/nct280
    A study on the radiation dose associated with cerebral CT angiography (CTA) and CT perfusion (CTP) was conducted on an anthropomorphic phantom with the aim of estimating the effective dose (E) and entrance skin dose (ESD) in the eyes and thyroid gland during different CTA and CTP protocols. The E was calculated to be 0.61 and 0.28 mSv in CTA with 100 and 80 kV(p), respectively. In contrast, CTP resulted in an estimated E of 2.74 and 2.07 mSv corresponding to 40 and 30 s protocols, respectively. The eyes received a higher ESD than the thyroid gland in all of these protocols. The results of this study indicate that combining both CTA and CTP procedures are not recommended in the stroke evaluation due to high radiation dose. Application of modified techniques in CTA (80 kV(p)) and CTP (30 s) is highly recommended in clinical practice for further radiation dose reduction.
  11. Multiphase renal CT in the evaluation of renal masses: is the nephrographic phase necessary?
    Songib NA, Nazri M, Yaakup NA, Nor HM, Sun Z
    Clin Imaging, 2013 Nov-Dec;37(6):1037-42.
    PMID: 24035803 DOI: 10.1016/j.clinimag.2013.08.005
    The aim of this study is to investigate the feasibility of eliminating the nephrographic phase from the four-phase renal computed tomography (CT) imaging to a three-phase protocol without affecting its diagnostic value. Thirty patients undergoing four-phase renal CT scans for assessment of renal lesions (>10 mm) were included in the study. A three-phase renal CT, without nephrographic phase, had similar diagnostic ability to a four-phase renal CT in the detection and characterization of renal lesions. A three-phase CT (plain, corticomedullary, and excretory phase) is therefore adequate in the clinical diagnosis of renal lesions.
  12. Fulltext Development of patient-specific 3D-printed breast phantom using silicone and peanut oils for magnetic resonance imaging
    Sindi R, Wong YH, Yeong CH, Sun Z
    Quant Imaging Med Surg, 2020 Jun;10(6):1237-1248.
    PMID: 32550133 DOI: 10.21037/qims-20-251
    Background: Despite increasing reports of 3D printing in medical applications, the use of 3D printing in breast imaging is limited, thus, personalized 3D-printed breast model could be a novel approach to overcome current limitations in utilizing breast magnetic resonance imaging (MRI) for quantitative assessment of breast density. The aim of this study is to develop a patient-specific 3D-printed breast phantom and to identify the most appropriate materials for simulating the MR imaging characteristics of fibroglandular and adipose tissues.

    Methods: A patient-specific 3D-printed breast model was generated using 3D-printing techniques for the construction of the hollow skin and fibroglandular region shells. Then, the T1 relaxation times of the five selected materials (agarose gel, silicone rubber with/without fish oil, silicone oil, and peanut oil) were measured on a 3T MRI system to determine the appropriate ones to represent the MR imaging characteristics of fibroglandular and adipose tissues. Results were then compared to the reference values of T1 relaxation times of the corresponding tissues: 1,324.42±167.63 and 449.27±26.09 ms, respectively. Finally, the materials that matched the T1 relaxation times of the respective tissues were used to fill the 3D-printed hollow breast shells.

    Results: The silicone and peanut oils were found to closely resemble the T1 relaxation times and imaging characteristics of these two tissues, which are 1,515.8±105.5 and 405.4±15.1 ms, respectively. The agarose gel with different concentrations, ranging from 0.5 to 2.5 wt%, was found to have the longest T1 relaxation times.

    Conclusions: A patient-specific 3D-printed breast phantom was successfully designed and constructed using silicone and peanut oils to simulate the MR imaging characteristics of fibroglandular and adipose tissues. The phantom can be used to investigate different MR breast imaging protocols for the quantitative assessment of breast density.

  13. Radiation dose reduction in thoracic and abdomen-pelvic CT using tube current modulation: a phantom study
    Sabarudin A, Mustafa Z, Nassir KM, Hamid HA, Sun Z
    J Appl Clin Med Phys, 2015 Jan;16(1):319-328.
    PMID: 28297258 DOI: 10.1120/jacmp.v16i1.5135
    This phantom study was designed to compare the radiation dose in thoracic and abdomen-pelvic CT scans with and without use of tube current modulation (TCM). Effective dose (ED) and size-specific dose estimation (SSDE) were calculated with the absorbed doses measured at selective radiosensitive organs using a thermoluminescence dosimeter-100 (TLD-100). When compared to protocols without TCM, the ED and SSDE were reduced significantly with use of TCM for both the thoracic and abdomen-pelvic CT. With use of TCM, the ED was 6.50±0.29 mSv for thoracic and 6.01±0.20 mSv for the abdomen-pelvic CT protocols. However without use of TCM, the ED was 20.07±0.24 mSv and 17.30±0.41 mSv for the thoracic and abdomen-pelvic CT protocols, respectively. The corresponding SSDE was 10.18±0.48 mGy and 11.96±0.27 mGy for the thoracic and abdomen-pelvic CT protocols with TCM, and 31.56±0.43 mGy and 33.23±0.05 mGy for thoracic and abdomen-pelvic CT protocols without TCM, respectively. The highest absorbed dose was measured at the breast with 8.58±0.12 mGy in the TCM protocols and 51.52±14.72 mGy in the protocols without TCM during thoracic CT. In the abdomen-pelvic CT, the absorbed dose was highest at the skin with 9.30±1.28 mGy and 29.99±2.23 mGy in protocols with and without use of TCM, respectively. In conclusion, the TCM technique results in significant dose reduction; thus it is to be highly recommended in routine thoracic and abdomen-pelvic CT. PACS numbers: 87.57.Q-, 87.57.qp, 87.53.Bn.
  14. Fulltext Comparison of luteal phase ovulation induction and ultra-short gonadotropin-releasing hormone agonist protocols in older patients undergoing in vitro fertilization
    Wang T, Sun Z, Lim JP, Yu Y
    Libyan J Med, 2019 Dec;14(1):1597327.
    PMID: 30935302 DOI: 10.1080/19932820.2019.1597327
    Many undergoing in vitro fertilization-embryo transfer (IVF-ET) procedures treatments have been tried for older infertile patients, but still can not reverse the aging effect on oocyte, and infertility treatment is expensive, even for people in developed countries. The study aimed to compare outcomes following the application of luteal phase ovulation induction (LPOI) and ultra-short gonadotropin-releasing hormone agonist (GnRH-a) protocols in patients aged more than 40 years undergoing IVF-ET and to examine the effectiveness and feasibility of LPOI. A total of 266 IVF-ET cycles in 155 patients aged 40 years and over were retrospectively analyzed. Of these patients, 105 underwent the ultra-short GnRH-a protocol (GnRH-a group) and 50 underwent LPOI (LPOI group). Various clinical outcomes were compared between these two groups using either t-tests or the chi-square test. The study showed patients in the LPOI group required a higher dosage of human menopausal gonadotropin and a lower dosage of recombinant follicle stimulating hormone than those in the GnRH-a group. Furthermore, though the total dosage of gonadotropin was higher in the LPOI, its cost was lower. Finally, fertilization rates were higher and high-quality embryo rates were lower in the LPOI group, and the live birth rate of LPOI group is higher than (GnRH-a group) . These between-group differences were all significant (P
  15. Fulltext 3D-Printed Coronary Plaques to Simulate High Calcification in the Coronary Arteries for Investigation of Blooming Artifacts
    Sun Z, Ng CKC, Wong YH, Yeong CH
    Biomolecules, 2021 09 03;11(9).
    PMID: 34572520 DOI: 10.3390/biom11091307
    The diagnostic value of coronary computed tomography angiography (CCTA) is significantly affected by high calcification in the coronary arteries owing to blooming artifacts limiting its accuracy in assessing the calcified plaques. This study aimed to simulate highly calcified plaques in 3D-printed coronary models. A combination of silicone + 32.8% calcium carbonate was found to produce 800 HU, representing extensive calcification. Six patient-specific coronary artery models were printed using the photosensitive polyurethane resin and a total of 22 calcified plaques with diameters ranging from 1 to 4 mm were inserted into different segments of these 3D-printed coronary models. The coronary models were scanned on a 192-slice CT scanner with 70 kV, pitch of 1.4, and slice thickness of 1 mm. Plaque attenuation was measured between 1100 and 1400 HU. Both maximum-intensity projection (MIP) and volume rendering (VR) images (wide and narrow window widths) were generated for measuring the diameters of these calcified plaques. An overestimation of plaque diameters was noticed on both MIP and VR images, with measurements on the MIP images close to those of the actual plaque sizes (<10% deviation), and a large measurement discrepancy observed on the VR images (up to 50% overestimation). This study proves the feasibility of simulating extensive calcification in coronary arteries using a 3D printing technique to develop calcified plaques and generate 3D-printed coronary models.
  16. Fulltext Potential Factors Influencing Repeated SARS Outbreaks in China
    Sun Z, Thilakavathy K, Kumar SS, He G, Liu SV
    Int J Environ Res Public Health, 2020 Mar 03;17(5).
    PMID: 32138266 DOI: 10.3390/ijerph17051633
    Within last 17 years two widespread epidemics of severe acute respiratory syndrome (SARS) occurred in China, which were caused by related coronaviruses (CoVs): SARS-CoV and SARS-CoV-2. Although the origin(s) of these viruses are still unknown and their occurrences in nature are mysterious, some general patterns of their pathogenesis and epidemics are noticeable. Both viruses utilize the same receptor-angiotensin-converting enzyme 2 (ACE2)-for invading human bodies. Both epidemics occurred in cold dry winter seasons celebrated with major holidays, and started in regions where dietary consumption of wildlife is a fashion. Thus, if bats were the natural hosts of SARS-CoVs, cold temperature and low humidity in these times might provide conducive environmental conditions for prolonged viral survival in these regions concentrated with bats. The widespread existence of these bat-carried or -released viruses might have an easier time in breaking through human defenses when harsh winter makes human bodies more vulnerable. Once succeeding in making some initial human infections, spreading of the disease was made convenient with increased social gathering and holiday travel. These natural and social factors influenced the general progression and trajectory of the SARS epidemiology. However, some unique factors might also contribute to the origination of SARS in Wuhan. These factors are discussed in different scenarios in order to promote more research for achieving final validation.
  17. Fulltext A perspective review on numerical simulations of hemodynamics in aortic dissection
    Wan Ab Naim WN, Ganesan PB, Sun Z, Chee KH, Hashim SA, Lim E
    ScientificWorldJournal, 2014;2014:652520.
    PMID: 24672348 DOI: 10.1155/2014/652520
    Aortic dissection, characterized by separation of the layers of the aortic wall, poses a significant challenge for clinicians. While type A aortic dissection patients are normally managed using surgical treatment, optimal treatment strategy for type B aortic dissection remains controversial and requires further evaluation. Although aortic diameter measured by CT angiography has been clinically used as a guideline to predict dilation in aortic dissection, hemodynamic parameters (e.g., pressure and wall shear stress), geometrical factors, and composition of the aorta wall are known to substantially affect disease progression. Due to the limitations of cardiac imaging modalities, numerical simulations have been widely used for the prediction of disease progression and therapeutic outcomes, by providing detailed insights into the hemodynamics. This paper presents a comprehensive review of the existing numerical models developed to investigate reasons behind tear initiation and progression, as well as the effectiveness of various treatment strategies, particularly the stent graft treatment.
  18. Dual-source CT coronary angiography: effectiveness of radiation dose reduction with lower tube voltage
    Sabarudin A, Md Yusof AK, Tay MF, Ng KH, Sun Z
    Radiat Prot Dosimetry, 2013;153(4):441-7.
    PMID: 22807493 DOI: 10.1093/rpd/ncs127
    This study was conducted to investigate the effectiveness of dose-saving protocols in dual-source computed tomography (CT) coronary angiography compared with invasive coronary angiography (ICA). On 50 patients who underwent coronary CT angiography was performed dual-source CT (DSCT) and compared with ICA procedures. Entrance skin dose (ESD), which was measured at the thyroid gland, and effective dose (E) were assessed for both imaging modalities. The mean ESD measured at the thyroid gland was the highest at 120 kVp, followed by the 100 kVp DSCT and the ICA protocols with 4.0±1.8, 2.7±1.0 and 1.1±1.2 mGy, respectively. The mean E was estimated to be 10.3±2.1, 6.2±2.3 and 5.3±3.4 mSv corresponding to the 120-kVp, 100-kVp DSCT and ICA protocols, respectively. The application of 100 kVp in DSCT coronary angiography is feasible only in patients with a low body mass index of <25 kg m(-2), which leads to a significant dose reduction with the radiation dose being equivalent to that of ICA.
  19. Fulltext Use of 100 kV versus 120 kV in computed tomography pulmonary angiography in the detection of pulmonary embolism: effect on radiation dose and image quality
    Gill MK, Vijayananthan A, Kumar G, Jayarani K, Ng KH, Sun Z
    Quant Imaging Med Surg, 2015 Aug;5(4):524-33.
    PMID: 26435916 DOI: 10.3978/j.issn.2223-4292.2015.04.04
    To determine the effective radiation dose and image quality resulting from 100 versus 120 kilovoltage (kV) protocols among patients referred for computed tomography pulmonary angiography (CTPA).
  20. Fulltext Incidental detection of sinus mucosal abnormalities on CT and MRI imaging of the head
    Nazri M, Bux SI, Tengku-Kamalden TF, Ng KH, Sun Z
    Quant Imaging Med Surg, 2013 Apr;3(2):82-8.
    PMID: 23630655 DOI: 10.3978/j.issn.2223-4292.2013.03.06
    To investigate the prevalence of incidental sinus abnormalities on CT and MRI imaging of the head, and identify if there is any correlation between patient symptomatology and image findings.
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