[Usefulness of Fenestrated Catheters for i.v. Contrast Infusion Cardiac CT Angiography for Newborn Patients during the Congenital Heart Disease]

Radiation dose proportions of localizer radiograph and bolus tracking in low-dose pediatric cardiothoracic computed tomography

BACKGROUND

Optimization of localizer radiograph and bolus tracking doses is necessary, as their dose proportion may increase with a decreasing diagnostic scan dose in pediatric cardiothoracic computed tomography (CT).

OBJECTIVE

To evaluate the radiation dose proportions of the localizer radiograph and bolus tracking in low-dose pediatric cardiothoracic CT.

MATERIALS AND METHODS

For low-dose pediatric cardiothoracic CT, a posteroanterior localizer radiograph was acquired with 80 kV, and 35 mA or 20 mA in 852 infants (age<1 year). Propensity score matching was employed in comparing the 35 mA and 20 mA groups on dose proportion, over z-axis proportion, visibility of anatomic landmarks, and image noise. The over z-axis coverage proportion was correlated with the dose proportion of the localizer radiograph in both groups. Additionally, bolus tracking was performed in 1,015 children (≤2 years). The effects of the number of monitoring scan, dose-length product of the diagnostic scan, age, and water-equivalent area of the scanned patient body on the radiation dose proportion of bolus tracking were evaluated.

RESULTS

The dose proportion of the localizer radiograph was significantly lower in the 20 mA group (2.5%, n = 94) than in the 35 mA group (6.5%, n = 94) (P < 0.001). While image noise was higher in the 20 mA group (2.1 Hounsfield units versus 1.0 Hounsfield units of the 35 mA-group, P < 0.001), all the anatomic landmarks remained visible in all cases. The over z-axis coverage proportion demonstrated high correlations with the dose proportion for both groups (R = 0.736, P < 0.001 for the 35 mA group and R = 0.660, P < 0.001 for the 20 mA group). The bolus tracking dose-length product proportion demonstrated the strongest positive correlation with the number of monitoring scans (R = 0.93, P < 0.001), while age, diagnostic scan dose-length product, and water-equivalent area showed weak negative correlations (R-values = -0.46~-0.50, P-values < 0.001).

CONCLUSIONS

In low-dose pediatric cardiothoracic CT, the dose proportion of the localizer radiograph can be substantially reduced with a low tube current setting while maintaining image quality. Additionally, minimization of the over z-axis coverage proportion merits attention. The number of monitoring scans is the most significant factor for increasing the radiation dose proportion of bolus tracking, especially in young ages.

Perforated intravenous catheter design is acceptable for the administration of contrast-enhanced computed tomography administration in cancer patients: Results of a pilot randomised controlled trial

BACKGROUND

Optimising first time success of peripheral intravenous catheter (PIVC) insertion and reducing intravenous (IV) complications in cancer patients undergoing contrast-enhanced computed tomography (CT) is vital to ensure vascular access preservation and diagnostic accuracy. The aim of this study was to test the feasibility of a randomised controlled trial (RCT) evaluating a novel perforated PIVC compared to a standard PIVC.

METHODS

A single centre, parallel-group, pilot RCT was conducted between March and May 2020. Adult participants diagnosed with cancer were randomised to a non-perforated PIVC (standard care) or a PIVC with a novel perforated design (intervention) for the administration of IV contrast. There were two primary outcomes: (1) feasibility of an adequately powered RCT with pre-established criteria; and (2) all-cause PIVC failure. Secondary outcomes included: first insertion success, modes of PIVC failure, dwell time, contrast injection parameters (volume and injection rate), contrast enhancement, radiographer satisfaction and adverse events.

RESULTS

Feasibility outcomes were met, except for eligibility (⩾90%) and recruitment (⩾90%). In total, 166 participants were screened, 128 (77%) were eligible and of these 101/128 (79%) were randomised; 50 to standard care and 51 to intervention. First time insertion rate was 94% (47/50) in standard care and 90% (46/50) in intervention. The median dwell time was 37 minutes (interquartile range (IQR): 25-55) in standard care and 35 minutes (IQR: 25-60) in the intervention group. There was one PIVC failure, a contrast media extravasation, in the intervention group (1/51; 2%). The desired contrast injection rate was not achieved in 4/101 (4%) of participants; two from each group. Radiographers were satisfied with the contrast flow rate.

CONCLUSIONS

This pilot RCT suggests perforated PIVCs provide expected flow rate, with no evidence of differences in contrast enhancement to non-perforated PIVCs. The feasibility of conducting a larger powered RCT was demonstrated.

Efficacy of the spiral flow generating extended tube during paediatric CCTA

INTRODUCTION

To compare the computed tomography (CT) number for paediatric cardiac computed tomography angiography (CCTA) and visualisation score of the three-dimensional (3D) images using the conventional T-shaped extended tube (T-tube) and spiral flow-generating extended tube (spiral-tube) connected between the contrast injector and cannula.

METHODS

In total, 108 patients suspected to have congenital heart disease (CHD) were considered for inclusion. We utilised the T-tube for intravenous contrast and spiral-tube in 54 patients each. Observers individually inspected randomized volume rendering images of the internal thoracic artery, each acquired from the with or without spiral-tube groups, using a four-point scale. We compared the mean CT number of the ascending aorta (AAO) and pulmonary artery (PA), contrast noise ratio (CNR), CT number for the AAO and PA enhancement ratio, and the visualisation scores between the groups.

RESULTS

There were no significant differences in patient characteristics between the with or without spiral-tube groups (p > 0.05). The mean CT number ±standard deviation for the AAO and PA, and the CNR without or with spiral-tube groups were 441.2 ± 89.2 and 489.8 ± 86.1 HU for the AAO, 436.3 ± 100.6 and 475.3 ± 85.2 HU for the PA, and 9.5 ± 2.2 and 10.8 ± 2.4 for the CNR, respectively (p < 0.05). In the spiral-tube group, the CT number, CNR, and visualisations score of the 3D images were significantly higher for the AAO and PA than those in the T-tube group (p < 0.05).

CONCLUSION

The spiral-tube proved to be beneficial in improving the CT number for the AAO and PA, CNR, and visualisation score compared with the conventional T-tube during paediatric CCTA.

IMPLICATIONS FOR PRACTICE

The spiral-tube may allow the visualisation of smaller blood vessels than those visualised by the conventional T-tube for paediatric patients in CCTA.