MATERIALS AND METHODS: Nine phantoms were fabricated with different bifurcation angles ranging from 55.3° to 134.5°. General X-ray and CCTA were employed to acquire 2D and 3D images of the bifurcation phantoms, respectively. Multiplanar reformation (MPR) and volume rendering technique (VRT) were used to measure the bifurcation angle between the left anterior descending (LAD) and left circumflex arteries (LCx). The measured angles were compared with the true values to determine the accuracy of each measurement technique. Inter-observer variability was evaluated. The two techniques were further applied on 50 clinical CCTA cases to verify its clinical value.
RESULTS: In the phantom setting, the mean absolute differences calculated between the true and measured angles by MPR and VRT were 2.4°±2.2° and 3.8°±2.9°, respectively. Strong correlation was found between the true and measured bifurcation angles. Furthermore, no significant differences were found between the bifurcation angles measured using either technique. In clinical settings, large difference of 12.0°±10.6° was found between the two techniques.
CONCLUSION: In the phantom setting, both techniques demonstrated a significant correlation to the true bifurcation angle. Despite the lack of agreement of the two techniques in the clinical context, our findings in phantoms suggest that MPR should be preferred to VRT for the measurement of coronary bifurcation angle by CCTA.
Methods: The algorithm for an IDR of 2.22 gI·s-1 was developed based on the relationship between VCE and contrast volume in 141 patients; test bolus parameters and characteristics in 75 patients; and, tube voltage in a phantom study. The algorithm was retrospectively tested in 45 patients who underwent retrospectively ECG-gated CCTA with a 100 kVp protocol. Image quality, TID and radiation dose exposure were compared with those produced using the 120 kVp and routine contrast protocols.
Results: Age, sex, body surface area (BSA) and peak contrast enhancement (PCE) were significant predictors for VCE (P<0.05). A strong linear correlation was observed between VCE and contrast volume (r=0.97, P<0.05). The 100-to-120 kVp contrast enhancement conversion factor (Ec) was calculated at 0.81. Optimal VCE (250 to 450 HU) and diagnostic image quality were obtained with significant reductions in TID (32.1%) and radiation dose (38.5%) when using 100 kVp and personalized contrast volume calculation algorithm compared with 120 kVp and routine contrast protocols (P<0.05).
Conclusions: The proposed algorithm could significantly reduce TID and radiation exposure while maintaining optimal VCE and image quality in CCTA with 100 kVp protocol.
METHODS: DNA methylation profiling was utilized to screen the differentially hypermethylated genes in OSCC. Three selected differentially-hypermethylated genes of p16, DDAH2 and DUSP1 were further validated for methylation status and protein expression. The correlation between demographic, clinicopathological characteristics, and survival rate of OSCC patients with hypermethylation of p16, DDAH2 and DUSP1 genes were analysed in the study.
RESULTS: Methylation profiling demonstrated 33 promoter hypermethylated genes in OSCC. The differentially-hypermethylated genes of p16, DDAH2 and DUSP1 revealed positivity of 78%, 80% and 88% in methylation-specific polymerase chain reaction and 24% and 22% of immunoreactivity in DDAH2 and DUSP1 genes, respectively. Promoter hypermethylation of p16 gene was found significantly associated with tumour site of buccal, gum, tongue and lip (P=0.001). In addition, DDAH2 methylation level was correlated significantly with patients' age (P=0.050). In this study, overall five-year survival rate was 38.1% for OSCC patients and was influenced by sex difference.
CONCLUSIONS: The study has identified 33 promoter hypermethylated genes that were significantly silenced in OSCC, which might be involved in an important mechanism in oral carcinogenesis. Our approaches revealed signature candidates of differentially hypermethylated genes of DDAH2 and DUSP1 which can be further developed as potential biomarkers for OSCC as diagnostic, prognostic and therapeutic targets in the future.
METHODS: A systematic search was performed in PubMed, the Cochrane library, CINAHL, Web of Science, ScienceDirect and Scopus, where 20 studies were selected for analysis of scanning parameters and CM reduction methods.
RESULTS: The mean effective dose (HE) ranged from 0.31 to 2.75 mSv at 80 kVp, 0.69 to 6.29 mSv at 100 kVp and 1.53 to 10.7 mSv at 120 kVp. Radiation dose reductions of 38 to 83% at 80 kVp and 3 to 80% at 100 kVp could be achieved with preserved image quality. Similar vessel contrast enhancement to 120 kVp could be obtained by applying iodine delivery rate (IDR) of 1.35 to 1.45 g s-1 with total iodine dose (TID) of between 10.9 and 16.2 g at 80 kVp and IDR of 1.08 to 1.70 g s-1 with TID of between 18.9 and 20.9 g at 100 kVp.
CONCLUSION: This systematic review found that radiation doses could be reduced to a rate of 38 to 83% at 80 kVp, and 3 to 80% at 100 kVp without compromising the image quality. Advances in knowledge: The suggested appropriate scanning parameters and CM reduction methods can be used to help users in achieving diagnostic image quality with reduced radiation dose.
METHODS: 41 medical personnel performing 79 procedures were monitored for their eye lens exposure using the NanoDot™ optically-stimulated luminescence dosimeters (OSLD) taped to the outer canthus of their eyes. The air-kerma area product (KAP), fluoroscopy time (FT) and number of procedure runs were also recorded.
RESULTS: KAP, FT and number of runs were strongly correlated. However, only weak to moderate correlations were observed between these parameters with the measured eye lens doses. The average median equivalent eye lens dose was 0.052 mSv (ranging from 0.0155 to 0.672 mSv). The eye lens doses of primary operators were found to be significantly higher than their assistants due to the closer proximity to the patient and X-ray tube. The left eye lens of the operators received the highest amount of radiation due to their habitual positioning towards the radiation source.
CONCLUSION: KAP and FT were not useful in predicting the equivalent eye lens dose exposure in interventional radiological procedures. Direct in vivo measurements were needed to provide a better estimate of the eye lens doses received by medical personnel during these procedures. This study highlights the importance of using direct measurement, such as OSLDs, instead of just indirect factors to monitor dose in the eye lens in radiological procedures.
Methods: This study was carried out between June and December 2017. All 48 paediatric surgeons currently working in Malaysia were invited to participate in a questionnaire-based survey to assess demographic characteristics and practices and perspectives regarding TOC.
Results: A total of 38 paediatric surgeons participated in the survey (response rate: 79.2%). Overall, 97.4% did not have an organised TOC model in their institution, with most (65.8%) caring for paediatric patients with complex surgical conditions until adulthood. Although the majority (86.8%) felt that care should be transitioned to adult surgeons with appropriate credentials, most surgeons (84.2%) nevertheless preferred to be involved in the management of adolescent patients after transition. However, there was no consensus regarding the most suitable age to begin the transition. Years of experience as a paediatric surgeon and place of practice did not affect overall TOC practice scores (P >0.050 each). The presence of adult comorbidities was considered the most common reason to initiate TOC (81.6%), while the lack of TOC guidelines was perceived to be the greatest barrier (84.2%).
Conclusion: This study provides a better understanding of TOC from the point of view of paediatric surgeons in Malaysia. However, further studies involving other stakeholders (i.e. patients and adult surgeons) are needed to help formulate a suitable and successful TOC model in this setting.
Methods: Two hundred fifty adult Cantonese-speaking patients of 18 years or older who underwent orthognathic treatment were recruited in the Prince Philip Dental Hospital of Hong Kong. Nine of an overall of 40 independent FACE-Q scales were selected and translated into Hong Kong Chinese. The reliability, validity, and test-retest reliability were examined using Cronbach's alpha, paired t test and Pearson's correlation coefficients.
Results: The Hong Kong Chinese version of the 9 FACE-Q scales was obtained by forward-backward translation. One hundred eight male (mean age, 25.57 ± 4.49) and 142 female (mean age, 24.61 ± 4.54) patients were recruited for the reliability and validation process. The internal consistency (0.89-0.97) and the test-retest reliability (0.73-0.90) were found to be high. The validity of the translated questionnaires was comparable with that of the original FACE-Q.
Conclusion: The results presented here prove that the 9 translated FACE-Q scales are reliable and valid instruments for research and clinical purposes in Hong Kong Chinese orthognathic patients.
MATERIALS AND METHODS: Prospectively ECG-triggered CCTA was performed using five commercially available CT scanners: 64-detector-row single source CT (SSCT), 2 × 32-detector-row-dual source CT (DSCT), 2 × 64-detector-row DSCT and 320-detector-row SSCT scanners. Absorbed doses were measured in 34 organs using pre-calibrated optically stimulated luminescence dosimeters (OSLDs) placed inside a standard female adult anthropomorphic phantom. HE was calculated from the measured organ doses and compared to the HE derived from the air kerma-length product (PKL) using the conversion coefficient of 0.014 mSv∙mGy-1∙cm-1 for the chest region.
RESULTS: Both breasts and lungs received the highest radiation dose during CCTA examination. The highest HE was received from 2 × 32-detector-row DSCT scanner (6.06 ± 0.72 mSv), followed by 64-detector-row SSCT (5.60 ± 0.68 and 5.02 ± 0.73 mSv), 2 × 64-detector-row DSCT (1.88 ± 0.25 mSv) and 320-detector-row SSCT (1.34 ± 0.48 mSv) scanners. HE calculated from the measured organ doses were about 38 to 53% higher than the HE derived from the PKL-to-HE conversion factor.
CONCLUSION: The radiation doses received from a prospectively ECG-triggered CCTA are relatively small and are depending on the scanner technology and imaging protocols. HE as low as 1.34 and 1.88 mSv can be achieved in prospectively ECG-triggered CCTA using 320-detector-row SSCT and 2 × 64-detector-row DSCT scanners.