Medical imaging has become a primary tool in diagnosis of injury and illness in children. However, it is important to remember that the decision to obtain imaging tests needs to be based on the potential benefits versus the potential risks. Among those risks is exposure to ionizing radiation. Common neuroimaging techniques that use radiation include x-ray (plain films), angiogram, radionuclide CSF shuntogram, proton emission tomography (PET) scan, and the CT scan. MRI does not use ionizing radiation but generally involves longer imaging times, requiring greater patient cooperation that can necessitate sedation. CT has the advantage of speed and greater sensitivity in evaluation of some pathologies, particularly in trauma.

We are all exposed to small amounts of radiation on a daily basis. There are risks involved with radiation exposure, the greatest concern being the risk of developing cancer. The low levels of radiation patients are exposed to during medical tests can be measured in units called millisieverts (mSv). There have been no published studies that show a link between radiation exposure of less than 10 mSv and cancer. However, there have been studies done on atomic bomb survivors, as well as workers who are exposed to radiation, which suggest that radiation exposure levels of 10–100 mSv can increase the risk of developing cancer (Miglioretti et al. 2013; Pearce et al. 2012). For comparison, a child who receives multiple CT scans during their lifespan can easily exceed 10 mSv. Modern CT scanners have substantially reduced the dose required for imaging.

The Pediatric Emergency Care Applied Research Network (PECARN) published a study that evaluated over 42,000 children cared for in 25 different emergency rooms, who had experienced head trauma within the previous 24 h and presented with a Glasgow Coma Scale of 14–15. The primary goal of this study was to identify children who had a minimal risk of developing a clinically important traumatic brain injury (ciTBI) after a head injury and, therefore, decrease the number of unnecessary CT scans that are performed on these children. For the purpose of the study, a ciTBI was defined as death from a TBI, need for a neurosurgical intervention following a TBI, intubation for more than 24 h following a TBI, or hospital admission for two or more nights associated with evidence of TBI on CT scan. From this very large study, an algorithm was developed to help guide whether or not a child with a traumatic head injury should undergo a head CT. The PECARN algorithm has guidelines for children younger than 2 years of age and for those 2 years and older. Children who are younger than 2 years should undergo a CT if they have a GCS of less than 14, altered mental status, or a palpable skull fracture. A CT should be considered in children younger than 2 years who have an occipital, parietal, or temporal hematoma, loss of consciousness (LOC) for greater than 5 s, a severe mechanism of injury, or an abnormal behavior reported by parents. In children 2 years and older, a head CT should be obtained for children with a GCS of less than 14, altered mental status, or signs of a basilar fracture. A head CT should be considered in this population if there has been vomiting, LOC, and severe mechanism of injury or the child self-reports a severe headache (Kuppermann et al. 2009). If this algorithm is applied, it can result in a reduction in the number of CT scans being done on children with minor head injuries.

Nurses should have a basic knowledge of the risks involved with radiation exposure, since the increasing media attention on the subject will likely result in questions and concerns from parents. Nurses must know how to educate patients and families about those risks while also explaining the necessity of the imaging. Nurses should be vigilant about reviewing medical records to ensure that patients are not receiving duplicate images that would expose them to additional radiation. It is important to consider that children are more sensitive to radiation than adults. It is essential that the “as low as reasonably achievable” (ALARA) principle be used in pediatric patients whenever safely possible. The goal of the ALARA principle is to achieve the best imaging using the least amount of radiation by utilizing weight-based protocols, improved shielding, consideration of alternative imaging methods (including MRI), use of limited view and reduced dose images, and avoidance of repeated images (Strauss and Kaste 2006).

The simplest way for us to think of medical radiation exposure is to compare it to the radiation we are exposed to on a day-to-day basis. Some examples of different levels of radiation exposure are listed on Table 18.2.

Dense parts of the body such as bone are easily imaged using an x-ray or CT, but soft tissue structures (including tumors) are often difficult to see. Intravenous contrast agents can assist with visualization of these structures and improve the accuracy of diagnosis prior to any surgical intervention. For example, contrast can help evaluate different types, sizes, and locations of brain or spine tumors for diagnosis and surgical planning. Contrast can also help characterize infections and vascular anomalies. After diagnosis and treatment of an infection, it can be used to determine response to the therapy and monitoring over the long term. It can also be used to follow vascular anomalies such as arteriovenous malformations (AVMs) or cavernous malformations over time and also to detect new anomalies before symptoms occur.

Iodinated (iodine-containing) contrast is most commonly used with CT. It can greatly enhance the clarity of vascular structures and provide improved visibility of tumors or abscesses. Gadolinium-based contrast has magnetic properties that are used to enhance brain and spine images created by MRI.

Prior to the administration of any contrast agent, nurses should consider the degree of renal function in children with known renal disease and whether they are receiving nephrotoxic medications like chemotherapy or some antibiotics. Use of iodinated contrast needs to be carefully considered for children who are dehydrated or who have impaired kidney function. Gadolinium contrast should be avoided in the child with significantly impaired kidney function.

In very rare cases, children can have an allergic reaction to both iodinated and gadolinium-based contrast, although allergic reactions, especially anaphylaxis, are much less common with gadolinium than to iodinated contrast. The current literature shows that there is no relationship between a shellfish or iodine allergy and an allergy to contrast agents (Schabelman and Witting 2010). Patients should be asked if they have any allergies or have had a previous reaction to contrast (Schabelman and Witting 2010). Patients who have had a reaction to contrast in the past, such as hives, pruritus, or shortness of breath, should be premedicated if contrast use cannot be avoided (e.g., steroids, antihistamine). When a patient has had a previous anaphylactic reaction, such as airway edema or difficulty breathing, alternative imaging should be considered.

One of the most important things about obtaining quality images in pediatric patients is ensuring that they stay still during the procedure. Every consideration should be made to avoid the use of sedation, as there are risks involved, most commonly respiratory depression. Additionally, there is some concern for the possible effects of sedation on the developing brain. There have been many studies done on rodents and primates demonstrating that there can be an effect on neuronal development when anesthesia is administered during the critical period of brain growth (Reddy 2012).

There is no consensus on how these animal studies translate to humans, and specifically children, undergoing anesthesia. A study of 2,608 children in Australia, of whom 321 had been exposed to anesthesia before age 3, found that children in the exposed group had an increased long-term risk of deficits in language and abstract reasoning at age 10 compared to unexposed children (Ing et al. 2012). In contrast, the Pediatric Anesthesia and Neurodevelopment Assessment Study (PANDA) was recently published and showed no evidence of any link between a single exposure to anesthesia in children below the age 3 and cognitive delays (Sun et al. 2016). Similarly, an international multicenter study also revealed no connection between a short period of general anesthesia (under 1 h) in children under two and neurocognitive delays (Davidson et al. 2016). The level of concern with the use of anesthesia in children is continuously evolving.

The American Academy of Pediatrics (AAP) defines the goals of sedation in the pediatric patient for diagnostic procedures as follows: to ensure the patient’s safety, to reduce physical discomfort and pain, to keep anxiety to a minimum, to limit movement to allow safe completion of the procedure, and to return the patient to their baseline prior to discharge (Charles and Stephen 2007; Coté and Wilson 2016). When a child must be sedated for imaging, it is preferable that it be done under the care of a trained pediatric anesthesiologist (Coté and Wilson 2016).

In most cases, sedation is not needed for a CT scan. Younger children can be safely restrained for the duration of the imaging, and older children are able to cooperate and hold still for the time needed to obtain a CT scan of the head or spine.

Sedation is usually required for an MRI in children younger than 6–8 years of age, with the exception of a half-Fourier acquisition single-shot turbo spin echo (HASTE), also known as a rapid sequence MRI. An MRI can cause a great amount of fear in children, as the machines are very loud and it requires laying still and alone in a small space (Arlachov and Ganatra 2012). Children are, however, less prone to claustrophobia which can be a problem with adults. Most children 8 years and older can be distracted with the use of a movie or music. Neonates can usually be scanned using a fast and feed protocol, where the infant is fed immediately prior to the study and will usually sleep for the duration of the scan. At around 3 months of age, sedation is usually necessary to obtain adequate imaging. With patience on the part of the nursing staff and cooperation from the technicians, nonsedated imaging can be achieved in many cases. Centers around the world are looking at alternative options to sedation, including sleep deprivation, hypnosis, distraction, melatonin, play therapy, and parental involvement (Arlachov and Ganatra 2012). Allowing a family member to be present during the exam can often be a great calming mechanism for children.

Limited imaging techniques that would be performed in a rapid manner are currently under development. These will have various clinical applications such as evaluation for only the presence of hydrocephalus.