Child-sizing Imaging and Interventions – Making challenges fun!

“Children are not small adults” – Many assumptions that we apply when performing imaging and interventions in adults do not hold true when applied in children. Children are more susceptible to the deleterious effect of radiation when compared to adult, especially in terms of cancer-risk associated with radiation. While the average radiation dose involved in medical imaging is significantly lower than that in radiation therapy, it is important for us to adopt the “As Low As Reasonably Appropriate” (ALARA) principle. When performing medical imaging with ionizing radiation, we need to use appropriate strategies to limit the radiation dose. Also, we need to consider alternative radiation-free imaging modalities, such as ultrasound and magnetic resonance imaging (MRI). MRI is the preferred imaging modality for many childhood conditions, given its high soft tissue contrast resolution and lack of ionizing radiation. The trade-off for performing MR scans is the relatively long scan time, during which the child would have to stay still and motionless. Motion artifacts result in poor image quality and potentially non-interpretable scans.

In order to keep young children still for MR scans, sedation or anaesthesia services are often required. While sedation is relatively safe in experienced hands, the risk to the patient is higher than that of non-sedated MRI because of the possibility of adverse reactions to medications, cardiovascular or respiratory events, as well as growing concerns regarding potential adverse neurocognitive effects associated with exposure to anaesthetic medications early in life. In addition, anaesthesia service is a scarce resource in most hospitals and often creates a bottleneck effect in examination scheduling, i.e. MR scans with sedation often have longer wait times than non-sedated MR studies.

Depending on the age of the child, various non-sedative strategies can be used to reduce need for sedation or anaesthesia. To run a successful non-sedated MR program, it involves collaborative teamwork between radiologist, MR technologists, referring clinical team, anaesthesiologists, play specialists and, most important, the child and his/her parent. This multidisciplinary team effort ensures proper patient selection, MR scan protocoling and creation of a child-friendly environment.

For baby aged less than 6 months, “feed-and-sleep” can be used to reduce the need of pharmacological sedation. With this technique, we make use of patients' daily feed and natural sleep pattern to let the baby fall asleep before start scanning. The parents would be briefed beforehand on when to feed the patient and the scan would be scheduled to fit with the feed schedule. The infant would be wrapped tightly in a pneumatic blanket to ensure comfort and minimise movement. The MR scanning room ambient light would be dimmed and “quieter” MR sequences would be selected to avoid waking the patient up.

Older children from 3 to 6 years old can avoid pharmacological sedation with the “Mock Scan MRI” programme, which was created in collaboration with play specialists. The mock scanner simulates the MRI experience including the noises the scanner makes. Selected patients are individually invited to a mock scan, during which education and training are provided to the child and parents. At the same time, the compliance level of the child is also assessed.

In addition to Mock MRI scan, MR-compatible video goggles can be worn by the child during scanning to provide audiovisual distraction. In our hospital, we provide a selection of movies for the child to select before he/she hops on the scanner. If the child is nervous, the parent and/or child play specialist may also be invited to accompany the child into the scanning room.

Finally, interventional Radiology (IR) has revolutionised the management of childhood diseases. With its minimally invasive nature, image-guided interventions are now the standard of care for many procedures which are traditionally delivered by paediatric surgeons, including vascular access, tumour biopsies and enteric access. Moving into the realm of interventional oncology, IR also has a growing role to play in management of locoregional tumour control through thermal ablative therapies and chemo-embolisation.