6. Behavioral methods for desensitization to the scanner environment

6.1 Introduction and Training Videos

Desensitization to the scanning procedures includes components completed prior to the scan and on the day of the scan. These are somewhat different for young versus older children. For the youngest children, the procedures of Almli and colleagues and those from our own experience with large-scale pediatric studies will be employed. Almli et al. have reported that these procedures result in successful scans for two thirds of their subjects. We have obtained even better success rates with older children. To begin, parents and children are introduced to the scanner environment so that they will have seen it prior to their child’s scan. The scanner environment has been decorated to make it child-friendly. For the youngest children, parents are provided with audio recordings (tape or CD) of scanner noises to play at home (during both sleep and wake periods) to accustom children to the sounds they will hear. Parents are also provided with fleece headphones so that these are familiar to the child prior to scanning. Parents are encouraged to incorporate these into play sessions with their child so that they are introduced within a pleasant context. For children ages three and above, the parents will be given a video made specifically to introduce children to the scanning procedures. This video follows a young girl through all the phases of an experiment (behavioral testing and scanning). This includes a demonstration of the girl receiving an MRI scan. Although very young children are not expected to understand the video, it provides a context for the parents to talk with their children about their scan and a prior reference for reassurance for preschool-age children who may wake up after arriving for their scan.

6.2 Sleeping Infants and Toddlers

For infants, scans are scheduled during periods where the child is typically asleep (at night). Toddlers and preschoolers will be brought, in pajamas, before or at their normal evening bedtime. Both parents and children are screened for contraindicated items (metal on clothing, implanted medical devices for parents). Children may be rocked or placed in cribs if they are not already asleep when arrive for their scan. Parents will be encouraged to use bedtime routines (feeding, reading, rocking) to assist their child in falling asleep. If children do not fall asleep within 60 minutes, the scan is typically rescheduled. Scans will be rescheduled up to two times before missing data is allowed for that child. Once asleep, young children will be transferred to the scanner bed. Infants will be kept as close to normal sleeping conditions as possible, if they are usually swaddled they will be swaddled for their scan.  Older children provided with blankets. Children are typically placed on their back, but other sleeping positions can also be accommodated if those are more typical for the child. Positioning may be assisted with rolled towels or memory foam padding. Earphone placement also assists positioning for toddlers and older children. When appropriate (given MR safety precautions), parents will be provided with hearing protection and invited to remain in the scanner room with their child. They may place a hand on the child’s legs to reassure the child of their presence should the child awake during the scan. Parents may also monitor their child and alert the MR technician to signs of wakening or distress in their children. Children are monitored during the scan for overt movement, waking, or signs of distress. If a parent is unable to be in the room with the scanner, another study staff member will serve in this role. If needed, children can be removed from the scanner within seconds and returned to their parents. Tangible reinforcers (such as stickers, pencils, model cars, etc.) are used to shape the children’s compliance and cooperation with the functional tasks and imaging procedures.

6.3 Awake Young Children

For older children, we will use procedures that we have already successfully employed with over 400 children from 5 to 18 years of age.  They will also be provided with a DVD of scanning procedures, just like the young children are.  Children and their parents arrived in the clinical area and were met by one of the investigators or the nurse coordinator.

 

On the day of the scan, children take a brief tour of the facility, including looking at the magnet, MRI head coil, patient bed, projector system, and response system. They practice each of the “magnet games,” by completing practice items on a personal computer. The child practices each task until it is clear that he or she understands it. At this point, the child enters the magnet room and a systematic, step- by-step approach is used to introduce all of the equipment (headphones, push button response system, etc.) and procedures.

 

In addition to the standard MRI equipment, the IRC uses an MRI-compatible audio-visual system (Resonance Technologies Inc., Van Nuys, California) that allows for presentation of high fidelity auditory and visual stimuli. In addition, popular videotapes are shown via the audiovisual system in order to distract and relax children during the portions of the scanning protocol that do not require their active participation. Typically, the child is provided with the video input as soon as he or she lies down on the scanner bed so that attention is already engaged with the program before entering the magnet. Once the child is acclimated to the scanner and demonstrated no overt signs of distress that would preclude the experiment, the scanning protocol begins. The technician visually monitors the child through the scanner bore and speaks with the child during the scan to let them know when the scanner noise will begin and whether the child can watch their video or must do one of the rehearsed tasks during this portion of the session. If the child produces overt movement, the scan is stopped. If movement was not due to stress, the session is continued with reminders to hold still. Otherwise the session is discontinued immediately.

 

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