Scanning Dos and Don'ts: Using Magnetic Resonance Imaging in Awake Children Aged 3 to 5 Years to Assess Brain Structure and Function

The goal of this protocol is to promote safe acquisition of high-quality brain images during early childhood using MRI. Early childhood presents unique challenges for awake scanning. This protocol introduces flexible, developmentally appropriate strategies to address them.

This protocol aims to increase transparency regarding how MRI data are successfully acquired with young children. To begin, introduce the child to the mock scanner suite and allow the child to explore the space on their own terms. Have the child listen to prerecorded scanner sounds that mimic those heard during the actual scan as an opportunity to scaffold their experience.

Allow the child to listen to the sounds. Ask them to identify what these sounds remind them of, and map the unfamiliar sounds to familiar ones to reduce anxiety. Remind the child to be still like a statue, but soft for the same duration as an actual magnetic resonance imaging sequence.

Then let the child practice lying still on the mock magnetic resonance imaging bed while watching a movie with scanner sounds playing. Provide feedback to the child on their motion and attention during this time. Continue practice until the child can remain still for two minutes straight.

Next, push the mock MRI scanner bed to move the child into the mock scanner, mimicking the real scanning experience. Repeat the practice of playing a movie, playing scanner noises, and monitoring motion. Continue until the child remains still for approximately five minutes.

Before the actual scan, ensure the family leaves all belongings in a locker outside the control and scanner room. Once in the control room, introduce the child to the magnetic resonance imaging operator and explain that this person will help take their brain pictures. Using a handheld metal detector, ensure the child and parent or caregiver do not have any metal on them.

If clothing has pockets, instruct them to check and empty their pockets. Instruct the child to stand straight like a pencil with hands at their sides and feet together. Pass the metal detector along the front of the body from feet to head, and then along the back.

Then ask the child to spread their arms like a starfish. Pass the metal detector along one leg, up the side, under the arm, along the arm and head, and down the opposite side. If the metal detector signals, check for metal, remove the item, and rescreen the child.

Then repeat the screening for the parent or caregiver. Once in the scanner suite, give the child time to explore the scanner space or ask questions before directing them to sit on the scanner bed. Provide a stool for the child to climb onto the scanner bed to increase autonomy.

When the child is sitting on the bed, show them the screen at the back of the scanner and remind them they will watch the movie using a mirror. Before placing ear protection, let the child feel it, and explain that it will reduce camera noise. Once ear protection is in place, put headphones on the child and have them lie down in the head coil.

Reposition the child until they are comfortable and the head is straight. Play part of the child's movie through the headphones to confirm the volume is comfortable. Then place a rolled towel under the child's knees to increase comfort and reduce leg movement.

Raise the MRI scanner bed. Once the bed is in the home position, place and adjust the mirror, so the child can see the full screen using the screen check. Ask the child to name the animals or colors they see.

Before moving into the scanner, check if the child is comfortable and remind the child to respond verbally when a staff member checks in between pictures. Remain close to the scanner bore and monitor the child for motion and alertness during the scan. Avoid inconsistent physical contact, unless the child becomes distressed.

Support transitions between sequences by talking to the child during long setups and instruct the scan buddy to avoid unnecessary talking. Communicate information to the child close to when it is relevant and in small chunks to avoid overwhelming them. Across studies one through four, most participants contributed at least one usable scan across time points with unsuccessful sessions primarily occurring in the youngest participants.

At participants'first time point, structural scan success rates were lowest in the three to four year age group at 87%while all participants aged five years and older successfully completed their first structural scan. At subsequent time points, structural scan success rates were again slightly lower in younger children compared to older children. For the task-free resting state functional scan using Inscapes, success rates at the first time point were lower than those for structural scans across all age groups.

At subsequent time points, task-free resting state scan success improved in the three to six year age groups to a mean of 65%while remaining stable at approximately 85%in children aged six years and older. Task-based functional scan success rates in studies one and three were lower than structural scan success rates. Setup time for magnetic resonance imaging scans was consistent across studies and age groups, typically ranging from 10 to 20 minutes.

In studies one and two, children spent similar amounts of time in the scanner, regardless of age. In study three, younger children spent less time in the scanner than older children. In study four, younger children tended to remain in the scanner longer than older children.

These differences in total in-scanner time are likely related to details of the specific studies, as some studies required reacquisition of unusable scans, whereas others discontinued scanning if specific scans were unusable. This protocol outlines practical steps from recruitment through scanning to enable successful awake neuroimaging in young children. Flexibility is crucial.

Adapting procedures to each child's needs in ways that help each child feel safe and ready to participate helps ensure optimal data quality.