Optimizing contrast injection dose for Cardiac Computed Tomography imaging for paediatrics

Abstract

Introduction

Cardiac Computed Tomography (CT) imaging is often regarded as a complex imaging technique in diagnostic imaging. Pediatric cardiac CT is even more challenging, as most related diseases are congenital, vary in nature, and commonly affect multiple structures of the heart. Furthermore, the techniques used for pediatric cardiac CT vary significantly with patient age and pathology. It is also difficult or impossible to control the breathing or heart rate of an infant. Finally, patient body weight and the size of the intravenous access often limit the amount of contrast that can be delivered to enhance the body structures. Since 2020, the Department of Radiology at the Hong Kong Children’s Hospital has conducted research to determine the optimal timing and contrast delivery regime for patients ranging from 0 to 18 years of age. The objective of this research is to minimize the contrast dose and related kVp used for Pediatric cardiac CT imaging³.

Cardiac Computed Tomography (CT) imaging is often regarded as a complex imaging technique in diagnostic imaging. Pediatric cardiac CT is even more challenging, as most related diseases are congenital, vary in nature, and commonly affect multiple structures of the heart. Furthermore, the techniques used for pediatric cardiac CT vary significantly with patient age and pathology. It is also difficult or impossible to control the breathing or heart rate of an infant. Finally, patient body weight and the size of the intravenous access often limit the amount of contrast that can be delivered to enhance the body structures. Since 2020, the Department of Radiology at the Hong Kong Children’s Hospital has conducted research to determine the optimal timing and contrast delivery regime for patients ranging from 0 to 18 years of age. The objective of this research is to minimize the contrast dose and related kVp used for Pediatric cardiac CT imaging³.

Materials and Methods

Approximately 200 patients were included in the study. The general principle was to estimate the required injection duration and match it with the maximum permissible injection rate, ensuring the total contrast volume remained below the maximum dose limit calculated by body weight. A multi-disciplinary team including medical physicists, nurses, radiographers, and radiologists was involved in the research program. Phantom studies were used to define the optimal contrast injection duration for achieving approximately 400 Hounsfield Units (HU) during imaging. Once the injection duration was confirmed, data on different body weights, injection rates, kVp settings, and the resulting HU values were recorded for analysis.

Approximately 200 patients were included in the study. The general principle was to estimate the required injection duration and match it with the maximum permissible injection rate, ensuring the total contrast volume remained below the maximum dose limit calculated by body weight. A multi-disciplinary team including medical physicists, nurses, radiographers, and radiologists was involved in the research program. Phantom studies were used to define the optimal contrast injection duration for achieving approximately 400 Hounsfield Units (HU) during imaging. Once the injection duration was confirmed, data on different body weights, injection rates, kVp settings, and the resulting HU values were recorded for analysis.

Results

A general formula for single and multiple organ enhancement during cardiac CT imaging has been developed. The formula is applicable to patients of different ages and body sizes, with or without metallic implants. The injection protocol is optimized to use the minimal contrast volume necessary to achieve approximately 400 HU during the examination.

A general formula for single and multiple organ enhancement during cardiac CT imaging has been developed. The formula is applicable to patients of different ages and body sizes, with or without metallic implants. The injection protocol is optimized to use the minimal contrast volume necessary to achieve approximately 400 HU during the examination.