Adolescents' attitudes to the COVID-19 vaccination.

Vaccines against COVID-19 are now available for adolescents in Hong Kong but vaccine hesitancy is a major barrier to herd immunity. This survey study explores Hong Kong adolescents' attitudes towards the COVID-19 vaccination. 2609 adolescents from across Hong Kong completed an online survey focused on the intent to vaccinate and the reasons for their choice. 39% of adolescents intended to take the COVID-19 vaccination and significant factors for this decision include: having at least one parent vaccinated, knowing somebody diagnosed with COVID-19 and receiving the influenza vaccine. Adolescents' major concerns were either the safety and efficacy of the vaccine or the risk of infection. This study has proved that even in adolescents the vaccine hesitancy model is prominent with adolescents' intentions highly related to confidence in the vaccine and perception of disease risk. Future interventions should target these specific concerns to ensure adolescents are well educated to overcome vaccine hesitancy.

Hong Kong Institute of Allergy and Hong Kong Society for Paediatric Immunology Allergy & Infectious Diseases joint consensus statement 2018 on vaccination in egg-allergic patients.

Vaccination of egg-allergic individuals has been a historical concern, particularly for influenza and measles-mumps-rubella-varicella vaccines that are developed in chicken egg embryos or chicken cell fibroblasts. The egg proteins in these vaccines were believed to trigger an immediate allergic reaction in egg-allergic individuals. However, recently published international guidelines have updated their recommendations and now state that these vaccines can be safely administered to egg-allergic individuals. This joint consensus statement by the Hong Kong Institute of Allergy and the Hong Kong Society for Paediatric Immunology Allergy & Infectious Diseases summarises the updates and provides recommendations for local general practitioners and paediatricians. Hong Kong Institute of Allergy and Hong Kong Society for Paediatric Immunology Allergy & Infectious Diseases joint consensus statement 2018 on vaccination in egg-allergic patients Background.

Paediatric case series of drug reaction with eosinophilia and systemic symptoms (DRESS): 12-year experience at a single referral centre in Hong Kong and the first reported use of infliximab.

Summary: DRESS (drug reaction with eosinophilia and systemic symptoms) is a rare but potentially life-threatening disorder characterized by fever, skin eruption, haematological abnormalities and multi-organ dysfunction after drug exposure. The pathophysiology is thought to be related to interactions between culprit drugs, viral reactivation and T-lymphocytes activation. We report 4 paediatric patients with DRESS who were treated at our centre over the past 12 years. Most cases improved after corticosteroids. Other immunosuppressive medications were attempted in refractory cases with varied outcomes. Patient 3 was the first reported case that involved the use of infliximab, a TNF-α inhibitor, for DRESS. Although clinical efficacy was not observed for this one patient, a previous study demonstrated that patients with DRESS, disease progression and HHV-6 reactivation had elevated pre-treatment TNF- α and IL-6 levels. Further research is needed to explore the role of these cytokines in DRESS.

Vitamin D status and peripheral arterial disease: evidence so far.

BACKGROUND: Vitamin D deficiency has recently been implicated as a contributory factor in the development of peripheral arterial disease (PAD). METHODS: A review of the published literature on PAD and vitamin D was undertaken using Medline, PubMed, and Embase, and cross-referenced. All relevant published papers on the subject were reviewed. RESULTS: Published studies have shown that there is a significant association between vitamin D and PAD. Populations with lower vitamin D levels are more likely to develop PAD in a graded manner. Higher amputation rates are also observed among patients with PAD and lower vitamin D levels. In addition, vitamin D deficiency is significantly associated with increased risk of cardiovascular adverse events. This was also observed in the mouse model where low vitamin D led to the development of atherosclerosis. CONCLUSION: This study shows that vitamin D deficiency could be an independent risk factor for the development of PAD and that this risk factor is easily correctable. Further studies should look into the effects of vitamin D supplementation in patients with PAD.

Effect of radiographic contrast material exposure on spiral CT attenuation of renal calculi.

RATIONALE AND OBJECTIVES: The authors performed this study to determine whether exposure of renal calculi to radiographic contrast material has an effect on the attenuation values at computed tomography (CT) performed with varying collimation widths. MATERIALS AND METHODS: Renal calculi (23 stones of various composition) were scanned with 1-, 3-, and 10-mm collimation. Stones were then exposed to a solution of radiographic contrast material for 5 minutes, washed with water, and rescanned 36 hours later. The reproducibility of the CT attenuation measurements on different days was evaluated by obtaining measurements in a subset of 16 renal stones on 4 different days. RESULTS: There was no statistically significant change in attenuation after contrast material exposure at narrow collimation. At wider collimation, statistically significant increases were noted in both attenuation and standard deviation. A small amount of variability between readings was noted on different days, with a minimal increase in attenuation each day. Correlation between readings remained very high. CONCLUSION: Exposure of stones to a radiographic contrast material had a statistically significant effect on CT attenuation values only at wide collimation. This may be related to technical factors including volume averaging. Absence of an effect at narrow collimation suggests that the attenuation values of renal stones do not significantly change after exposure to contrast material.

Correction of helical CT attenuation values with wide beam collimation: in vitro test with urinary calculi.

RATIONALE AND OBJECTIVES: Urinary calculi are now commonly detected with helical computed tomography (CT), and it has been proposed that stone composition can be determined from CT attenuation values. However, typical scans are made with a beam collimation of 5 mm or more, resulting in volume averaging and reduction in accuracy of attenuation measurement. The authors tested a model for correction of errors in attenuation values, even at section widths larger than the width of the object. MATERIALS AND METHODS: Human urinary stones were scanned with helical CT at different beam collimation widths. A computer model was used to predict the effect of beam width and stone size on accuracy of measured attenuation. RESULTS: At 3-mm collimation, the model corrected the attenuation readings with an underestimation of 12% +/- 1 (compared with values at 1-mm collimation; 127 stones; diameters of 1.7-11.3 mm). With attenuation measured at 10-mm collimation, the model underestimated the true value by 34% +/- 3 (103 stones), with a significant negative correlation with stone diameter on magnitude of error (diameters of 3.0-11.3 mm). Correlation of data from patient scans with subsequent in vitro scanning of the same stones confirmed the validity of the model, but corrected in vivo scans consistently yielded lower values for the stones than in vitro. CONCLUSION: Volume averaging effects on attenuation in helical CT are predictable in vitro for urinary calculi--and presumably for other roughly spherical structures--as long as section width does not excessively exceed the diameter of the structure.

Calcium stone fragility is predicted by helical CT attenuation values.

BACKGROUND AND PURPOSE: Helical CT has become the preferred method for imaging urinary calculi, and so it would be useful if data from helical CT could also be used to predict the number of shockwaves (SWs) needed to break a given stone. METHODS AND MATERIALS: We measured the number of SWs required to comminute calcium stones in vitro. RESULTS: The SW requirement correlated with stone size (volume, weight, diameter) and with helical CT attenuation values when the scans were performed at 3-mm collimation. When CT scans were performed at 1-mm collimation, the number of SWs needed for comminution did not correlate with helical CT attenuation values. This result indicates that the correlation with 3-mm scans was attributable to volume-averaging effects, in which smaller stones yield smaller attenuation values. That is, attenuation values from helical CT at larger beam collimation widths contain information about stone size that can be exploited to predict the fragility of calcium stones. We observed that for calcium stones, the number of SWs to comminution was generally less than half the stone CT attenuation value in Hounsfield units. This "half-attenuation rule" predicted the number of SWs needed to complete fragmentation for 95% of calcium stones (24/24 calcium oxalate monohydrate, 13/13 hydroxyapatite, 8/10 brushite stones). CONCLUSION: This in vitro study suggests that it may be possible to predict effective SW dose using helical CT prior to lithotripsy.

Helical CT of urinary calculi: effect of stone composition, stone size, and scan collimation.

OBJECTIVE: Helical CT has become the preferred methodology for identifying urinary calculi. However, the ability to predict stone composition, which influences patient treatment, depends on the accurate measurement of the radiographic attenuation of stones. We studied the effects of stone composition, stone size, and scan collimation width on the measurement of attenuation in vitro. MATERIALS AND METHODS: One hundred twenty-seven human urinary calculi of known composition and size were scanned at 120 kVp, 240 mA, and a 1:1 pitch at different collimations. A model, based on the physics of helical CT, was used to predict the effect of scan collimation width and stone size on measured attenuation. RESULTS: At a 1-mm collimation, stone groups could be differentiated by attenuation: the attenuation of uric acid was less than that of cystine or struvite, which overlapped; these were less than the attenuation of calcium oxalate monohydrate, which was in turn lower than that of brushite and hydroxyapatite, which overlapped and showed the highest values. At a wider collimation, attenuation was lower and the ability to differentiate stone composition was lost. Attenuation also decreased with smaller stones. At a 10-mm collimation, some uric acid stones (

Reliability and role of plain film radiography and CT in the diagnosis of small-bowel obstruction.

OBJECTIVE: We compare the reliability and define the role of plain film radiography and CT in the assessment of various severities of small-bowel obstruction. MATERIALS AND METHODS: A blinded retrospective analysis was done on 78 patients who underwent plain abdominal radiography, CT, and enteroclysis to assess for suspected small-bowel obstruction. The findings at enteroclysis and the clinical outcomes were used as standards of reference. RESULTS: The sensitivity of plain film radiography for revealing small-bowel obstruction was 69% (44/64), and its specificity was 57% (8/14). Overall accuracy of plain film radiography was 67% (52/78). The sensitivity and specificity of CT were 64% (41/64) and 79% (11/ 14), respectively. Overall accuracy of CT was 67% (52/78). When obstructions were classified as low- and high-grade partial obstruction, plain film radiography and CT had sensitivities of 86% (24/28) and 82% (23/28), respectively, for high-grade obstruction and 56% (20/36) and 50% (18/36), respectively, for low-grade obstruction. CT revealed the cause of the small-bowel obstruction in 95% (39/41) of those patients in who CT correctly showed the obstruction. CONCLUSION: Plain film radiography and CT had similar overall accuracies in showing small-bowel obstruction of various severities. Plain film radiography should remain the initial method of imaging patients with suspected small-bowel obstruction. The ability of CT to show the cause of small-bowel obstruction makes CT an important additional diagnostic tool when specific management issues must be addressed.

Obstruction of the small intestine: accuracy and role of CT in diagnosis.

The reliability of abdominal computed tomography (CT) in the assessment of varying degrees of small bowel obstruction (SBO) was evaluated by using results at enteroclysis and clinical outcome as standards of reference. A blinded retrospective analysis was performed of the studies of 55 patients who underwent both CT and enteroclysis in the course of assessment for suspected SBO. Nine patients had no obstruction, 40 patients had obstruction due to adhesions, and six patients had tumor-related obstruction. CT results were used to identify correctly 63% (29 of 46) of those who had SBO and 78% (seven of nine) of the patients who did not. The overall accuracy of the CT interpretations to help establish diagnosis was 65% (36 of 55). When obstructions were classified into low- and high-grade partial obstruction, CT results could be used to identify correctly 81% (17 of 21) of high-grade SBOs and 48% (12 of 25) of low-grade SBOs. The procedure yielded two false-positive and 13 false-negative results for patients with low-grade obstruction, revealed masses in all six cases with tumor-related obstruction, and helped predict the correct cause in all true-positive cases.

Intraoperative ultrasound of hepatic tumors.

Intraoperative ultrasound (IOUS) scanning of liver masses was compared with those of preoperative computed tomography (CT) and intraoperative palpation. Between March 1989 and May 1991, 24 patients underwent 25 IOUS procedures during laparotomy. Intraoperative ultrasound provided more information than the other modalities in 10 patients (40%) and affected operative management in eight patients (32%). It was concluded that IOUS, when used in conjunction with CT and palpation, is an important technique in the surgical management of patients with hepatic neoplasms.