Implementation of patient-tailored contrast volumes based on body surface area and heart rate harmonizes contrast enhancement and reduces contrast load in small patients in portal venous phase abdominal CT

PURPOSE

The aim of this study was to evaluate the impact of a patient-tailored contrast volume protocol on portal venous phase abdominal CT-images compared to a fixed volume protocol in daily radiological practice.

METHOD

Data of 77 patients who underwent two contrast-enhanced CT-examinations were collected. The first examination was performed with a fixed contrast volume (95 ml), the follow-up examination was performed with a patient-tailored contrast volume based on patient's BSA and heart rate. The patient-tailored volume was calculated by a software application integrated in the interface of the injection pump. Two independent radiologists assessed subjective and objective image quality. Differences in enhancement and contrast volumes between both protocols were analysed.

RESULTS

Despite a significant contrast volume reduction in women and in patients with low to normal BMI, enhancement was more consistent over different BMI-categories in the patient-tailored contrast volume protocol and there was no significant difference in subjective image quality between both injection protocols.

CONCLUSIONS

A patient-tailored contrast volume protocol based on BSA and heart rate can be considered in daily radiological practice to decrease contrast volumes in women and in low to normal BMI patients and to achieve more consistent contrast enhancement across different BMI-categories in venous phase abdominal CT.

γ-H2AX foci as in vivo effect biomarker in children emphasize the importance to minimize x-ray doses in paediatric CT imaging

Objectives

Investigation of DNA damage induced by CT x-rays in paediatric patients versus patient dose in a multicentre setting.

Methods

From 51 paediatric patients (median age, 3.8 years) who underwent an abdomen or chest CT examination in one of the five participating radiology departments, blood samples were taken before and shortly after the examination. DNA damage was estimated by scoring γ-H2AX foci in peripheral blood T lymphocytes. Patient-specific organ and tissue doses were calculated with a validated Monte Carlo program. Individual lifetime attributable risks (LAR) for cancer incidence and mortality were estimated according to the BEIR VII risk models.

Results

Despite the low CT doses, a median increase of 0.13 γ-H2AX foci/cell was observed. Plotting the induced γ-H2AX foci versus blood dose indicated a low-dose hypersensitivity, supported also by an in vitro dose–response study. Differences in dose levels between radiology centres were reflected in differences in DNA damage. LAR of cancer mortality for the paediatric chest CT and abdomen CT cohort was 0.08 and 0.13 ‰ respectively.

Conclusion

CT x-rays induce DNA damage in paediatric patients even at low doses and the level of DNA damage is reduced by application of more effective CT dose reduction techniques and paediatric protocols.

Key Points

• CT induces a small, significant number of double-strand DNA breaks in children.

• More effective CT dose reduction results in less DNA damage.

• Risk estimates based on the LNT hypothesis may represent underestimates.