propofol IV administration will be given if needed to maintain sedation

In this outcome measure percentage of time for which participant had maintained PSSS score of 2 was reported. PSSS score ranges from 0 to 5, where 0= sedation with abnormal physiologic parameters requiring acute intervention, 1= sedation with normal vital signs, but requiring airway intervention, 2= no movement during procedure, no frown, no verbalization of complaint indicating no pain and anxiety, 3= no movement during procedure but expression of pain and anxiety on face, verbalization of complaint, requiring help positioning, 4= movement during procedure requiring gentle immobilization for positioning, verbalization of some discomfort or stress, but no crying or shouting that expresses stress or objection, 5= movement impeding proceduralist and requiring forceful immobilization, crying or shouting during procedure, but vocalization not required. Higher score indicated less sedation.

Participants who did not have PRO administered were censored.

Emergence time: time from the end of the MRI scan to when the participant met a Modified Aldrete score >=9. Participants who were withdrawn or discharged without reaching a Modified Aldrete score >=9, were censored, time computed from end of MRI scan to time of the last clinical assessment (vital signs). Zero minute was used as the censored time if no vital signs were taken during the post-MRI recovery period. Modified Aldrete score: validated observational medical scoring system that allowed verbal prompts for the measurement of recovery after anesthesia (post anesthesia) which included items: activity, respiration, circulation, consciousness, and oxygenation. Each item was scored from 0 to 2, higher scores signified better recovery. The scores of each item were summed to obtain a total score of 0 to 10, where higher scores indicated well recovered participant post anesthesia.

Day 1: Participants aged >=1 month to <2 years, were randomized to receive a loading dose of DEX 1 mcg/kg over 10 minutes as IV infusion followed by continuous maintenance dose of DEX 1 mcg/kg/hour IV. If an adequate level of sedation was not achieved, participants were co-administered with PRO IV per PI clinical judgment. MRI scan started on achieving an adequate sedation level. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours. Treatment PRO first bolus strength would be 500 mcg/kg and then maintenance infusion at 50 mcg/kg/min. Participants were monitored for a minimum of 1 hour after completion of MRI scan. Day 2: Participants were followed up after 24 hours (+/- 2 hours) post discontinuation of DEX. Participants had a long-term follow-up contact via phone call at 28 to 31 days post last administration of study drug.

Day 1: Participants aged >=1 month to <2 years, were randomized to receive a loading dose of DEX 1.5 mcg/kg over 10 minutes as IV infusion followed by continuous maintenance dose of DEX 1.5 mcg/kg/hour IV. If an adequate level of sedation was not achieved, participants were co-administered with PRO IV per PI clinical judgment. MRI scan started on achieving an adequate sedation level. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours. Treatment PRO first bolus strength would be 500 mcg/kg and then maintenance infusion at 50 mcg/kg/min. Participants were monitored for a minimum of 1 hour after completion of MRI scan. Day 2: Participants were followed up after 24 hours (+/- 2 hours) post discontinuation of DEX. Participants had a long-term follow-up contact via phone call at 28 to 31 days post last administration of study drug.

Day 1: Participants aged >=2 years to <17 years, were randomized to receive a loading dose of DEX 0.5 mcg/kg over 10 minutes as IV infusion followed by continuous maintenance dose of DEX 0.5 mcg/kg/hour IV. If an adequate level of sedation was not achieved, participants were co-administered with PRO IV per PI clinical judgment. MRI scan started on achieving an adequate sedation level. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours. Treatment PRO first bolus strength would be 500 mcg/kg and then maintenance infusion at 50 mcg/kg/min. Participants were monitored for a minimum of 1 hour after completion of MRI scan. Day 2: Participants were followed up after 24 hours (+/- 2 hours) post discontinuation of DEX. Participants had a long-term follow-up contact via phone call at 28 to 31 days post last administration of study drug.

Day 1: Participants aged >=2 years to <17 years, were randomized to receive a loading dose of DEX 1.2 mcg/kg over 10 minutes as IV infusion followed by continuous maintenance dose of DEX 1 mcg/kg/hour IV. If an adequate level of sedation was not achieved, participants were co-administered with PRO IV per PI clinical judgment. MRI scan started on achieving an adequate sedation level. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours. Treatment PRO first bolus strength would be 500 mcg/kg and then maintenance infusion at 50 mcg/kg/min. Participants were monitored for a minimum of 1 hour after completion of MRI scan. Day 2: Participants were followed up after 24 hours (+/- 2 hours) post discontinuation of DEX. Participants had a long-term follow-up contact via phone call at 28 to 31 days post last administration of study drug.

Day 1: Participants aged >=2 years to <17 years, were randomized to receive a loading dose of DEX 2 mcg/kg over 10 minutes as IV infusion followed by continuous maintenance dose of DEX 1.5 mcg/kg/hour IV. If an adequate level of sedation was not achieved, participants were co-administered with PRO IV per PI clinical judgment. MRI scan started on achieving an adequate sedation level. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours. Treatment PRO first bolus strength would be 500 mcg/kg and then maintenance infusion at 50 mcg/kg/min. Participants were monitored for a minimum of 1 hour after completion of MRI scan. Day 2: Participants were followed up after 24 hours (+/- 2 hours) post discontinuation of DEX. Participants had a long-term follow-up contact via phone call at 28 to 31 days post last administration of study drug.

Participants aged >=2 years to <17 years, were randomized to receive a loading dose of DEX 0.5 mcg/kg over 10 minutes followed by maintenance dose of DEX 0.5 mcg/kg/hour. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=2 years to <17 years, were randomized to receive a loading dose of DEX 2 mcg/kg over 10 minutes followed by maintenance dose of DEX 1.5 mcg/kg/hour. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=2 years to <17 years, were randomized to receive a loading dose of DEX 1.2 mcg/kg over 10 minutes followed by maintenance dose of DEX 1 mcg/kg/hour. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=2 years to <17 years, were randomized to receive a loading dose of DEX 0.5 mcg/kg over 10 minutes followed by maintenance dose of DEX 0.5 mcg/kg/hour. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=1 month to <2 years and >=2 years to <17 years were randomized to receive a loading dose of DEX 1.5 mcg/kg over 10 minutes followed by maintenance dose of DEX 1.5 mcg/kg/hour and a loading dose of DEX 2 mcg/kg over 10 minutes followed by maintenance dose of DEX 1.5 mcg/kg/hour respectively. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=1 month to <2 years and >=2 years to <17 years were randomized to receive a loading dose of DEX 1 mcg/kg over 10 minutes followed by maintenance dose of DEX 1 mcg/kg/hour and a loading dose of DEX 1.2 mcg/kg over 10 minutes followed by maintenance dose of DEX 1 mcg/kg/hour respectively. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=1 month to <2 years and >=2 years to <17 years were randomized to receive a loading dose of DEX 0.5 mcg/kg over 10 minutes followed by maintenance dose of DEX 0.5 mcg/kg/hour respectively. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=1 month to < 2 years, were randomized to receive a loading dose of DEX 1 mcg/kg over 10 minutes followed by maintenance dose of DEX 1 mcg/kg/hour. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=1 month to < 2 years, were randomized to receive a loading dose of DEX 1.5 mcg/kg over 10 minutes followed by maintenance dose of DEX 1.5 mcg/kg/hour. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=2 years to <17 years, were randomized to receive a loading dose of DEX 0.5 mcg/kg over 10 minutes followed by maintenance dose of DEX 0.5 mcg/kg/hour. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=2 years to <17 years, were randomized to receive a loading dose of DEX 1.2 mcg/kg over 10 minutes followed by maintenance dose of DEX 1 mcg/kg/hour. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=2 years to <17 years, were randomized to receive a loading dose of DEX 2 mcg/kg over 10 minutes followed by maintenance dose of DEX 1.5 mcg/kg/hour. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=1 month to <2 years and >=2 years to <17 years were randomized to receive a loading dose of DEX 0.5 mcg/kg over 10 minutes followed by maintenance dose of DEX 0.5 mcg/kg/hour respectively. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=1 month to <2 years and >=2 years to <17 years were randomized to receive a loading dose of DEX 1 mcg/kg over 10 minutes followed by maintenance dose of DEX 1 mcg/kg/hour and a loading dose of DEX 1.2 mcg/kg over 10 minutes followed by maintenance dose of DEX 1 mcg/kg/hour respectively. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=1 month to <2 years and >=2 years to <17 years were randomized to receive a loading dose of DEX 1.5 mcg/kg over 10 minutes followed by maintenance dose of DEX 1.5 mcg/kg/hour and a loading dose of DEX 2 mcg/kg over 10 minutes followed by maintenance dose of DEX 1.5 mcg/kg/hour respectively. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=2 years to <17 years, were randomized to receive a loading dose of DEX 0.5 mcg/kg over 10 minutes followed by maintenance dose of DEX 0.5 mcg/kg/hour. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=2 years to <17 years, were randomized to receive a loading dose of DEX 1.2 mcg/kg over 10 minutes followed by maintenance dose of DEX 1 mcg/kg/hour. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=2 years to <17 years, were randomized to receive a loading dose of DEX 2 mcg/kg over 10 minutes followed by maintenance dose of DEX 1.5 mcg/kg/hour. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=1 month to <2 years and >=2 years to <17 years were randomized to receive a loading dose of DEX 0.5 mcg/kg over 10 minutes followed by maintenance dose of DEX 0.5 mcg/kg/hour respectively. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=1 month to <2 years and >=2 years to <17 years were randomized to receive a loading dose of DEX 1 mcg/kg over 10 minutes followed by maintenance dose of DEX 1 mcg/kg/hour and a loading dose of DEX 1.2 mcg/kg over 10 minutes followed by maintenance dose of DEX 1 mcg/kg/hour respectively. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=1 month to <2 years and >=2 years to <17 years were randomized to receive a loading dose of DEX 1.5 mcg/kg over 10 minutes followed by maintenance dose of DEX 1.5 mcg/kg/hour and a loading dose of DEX 2 mcg/kg over 10 minutes followed by maintenance dose of DEX 1.5 mcg/kg/hour respectively. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=1 month to < 2 years, were randomized to receive a loading dose of DEX 1.5 mcg/kg over 10 minutes followed by maintenance dose of DEX 1.5 mcg/kg/hour. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=2 years to <17 years, were randomized to receive a loading dose of DEX 0.5 mcg/kg over 10 minutes followed by maintenance dose of DEX 0.5 mcg/kg/hour. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=2 years to <17 years, were randomized to receive a loading dose of DEX 1.2 mcg/kg over 10 minutes followed by maintenance dose of DEX 1 mcg/kg/hour. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=2 years to <17 years, were randomized to receive a loading dose of DEX 2 mcg/kg over 10 minutes followed by maintenance dose of DEX 1.5 mcg/kg/hour. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=1 month to <2 years and >=2 years to <17 years were randomized to receive a loading dose of DEX 0.5 mcg/kg over 10 minutes followed by maintenance dose of DEX 0.5 mcg/kg/hour respectively. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=1 month to <2 years and >=2 years to <17 years were randomized to receive a loading dose of DEX 1 mcg/kg over 10 minutes followed by maintenance dose of DEX 1 mcg/kg/hour and a loading dose of DEX 1.2 mcg/kg over 10 minutes followed by maintenance dose of DEX 1 mcg/kg/hour respectively. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=1 month to <2 years and >=2 years to <17 years were randomized to receive a loading dose of DEX 1.5 mcg/kg over 10 minutes followed by maintenance dose of DEX 1.5 mcg/kg/hour and a loading dose of DEX 2 mcg/kg over 10 minutes followed by maintenance dose of DEX 1.5 mcg/kg/hour respectively. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=2 years to <17 years, were randomized to receive a loading dose of DEX 0.5 mcg/kg over 10 minutes followed by maintenance dose of DEX 0.5 mcg/kg/hour. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=2 years to <17 years, were randomized to receive a loading dose of DEX 1.2 mcg/kg over 10 minutes followed by maintenance dose of DEX 1 mcg/kg/hour. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=2 years to <17 years, were randomized to receive a loading dose of DEX 2 mcg/kg over 10 minutes followed by maintenance dose of DEX 1.5 mcg/kg/hour. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=1 month to <2 years and >=2 years to <17 years were randomized to receive a loading dose of DEX 0.5 mcg/kg over 10 minutes followed by maintenance dose of DEX 0.5 mcg/kg/hour respectively. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=1 month to <2 years and >=2 years to <17 years were randomized to receive a loading dose of DEX 1 mcg/kg over 10 minutes followed by maintenance dose of DEX 1 mcg/kg/hour and a loading dose of DEX 1.2 mcg/kg over 10 minutes followed by maintenance dose of DEX 1 mcg/kg/hour respectively. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=1 month to <2 years and >=2 years to <17 years were randomized to receive a loading dose of DEX 1.5 mcg/kg over 10 minutes followed by maintenance dose of DEX 1.5 mcg/kg/hour and a loading dose of DEX 2 mcg/kg over 10 minutes followed by maintenance dose of DEX 1.5 mcg/kg/hour respectively. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=2 years to <17 years, were randomized to receive a loading dose of DEX 0.5 mcg/kg over 10 minutes followed by maintenance dose of DEX 0.5 mcg/kg/hour. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=2 years to <17 years, were randomized to receive a loading dose of DEX 1.2 mcg/kg over 10 minutes followed by maintenance dose of DEX 1 mcg/kg/hour. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=2 years to <17 years, were randomized to receive a loading dose of DEX 2 mcg/kg over 10 minutes followed by maintenance dose of DEX 1.5 mcg/kg/hour. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=1 month to <2 years and >=2 years to <17 years were randomized to receive a loading dose of DEX 0.5 mcg/kg over 10 minutes followed by maintenance dose of DEX 0.5 mcg/kg/hour respectively. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=1 month to <2 years and >=2 years to <17 years were randomized to receive a loading dose of DEX 1 mcg/kg over 10 minutes followed by maintenance dose of DEX 1 mcg/kg/hour and a loading dose of DEX 1.2 mcg/kg over 10 minutes followed by maintenance dose of DEX 1 mcg/kg/hour respectively. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=1 month to <2 years and >=2 years to <17 years were randomized to receive a loading dose of DEX 1.5 mcg/kg over 10 minutes followed by maintenance dose of DEX 1.5 mcg/kg/hour and a loading dose of DEX 2 mcg/kg over 10 minutes followed by maintenance dose of DEX 1.5 mcg/kg/hour respectively. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=2 years to <17 years, were randomized to receive a loading dose of DEX 0.5 mcg/kg over 10 minutes followed by maintenance dose of DEX 0.5 mcg/kg/hour. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=2 years to <17 years, were randomized to receive a loading dose of DEX 1.2 mcg/kg over 10 minutes followed by maintenance dose of DEX 1 mcg/kg/hour. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=2 years to <17 years, were randomized to receive a loading dose of DEX 2 mcg/kg over 10 minutes followed by maintenance dose of DEX 1.5 mcg/kg/hour. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=1 month to <2 years and >=2 years to <17 years were randomized to receive a loading dose of DEX 0.5 mcg/kg over 10 minutes followed by maintenance dose of DEX 0.5 mcg/kg/hour respectively. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=1 month to <2 years and >=2 years to <17 years were randomized to receive a loading dose of DEX 1 mcg/kg over 10 minutes followed by maintenance dose of DEX 1 mcg/kg/hour and a loading dose of DEX 1.2 mcg/kg over 10 minutes followed by maintenance dose of DEX 1 mcg/kg/hour respectively. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.

Participants aged >=1 month to <2 years and >=2 years to <17 years were randomized to receive a loading dose of DEX 1.5 mcg/kg over 10 minutes followed by maintenance dose of DEX 1.5 mcg/kg/hour and a loading dose of DEX 2 mcg/kg over 10 minutes followed by maintenance dose of DEX 1.5 mcg/kg/hour respectively. If adequate sedation was not achieved PRO was co-administered. DEX and PRO (if needed) continued till completion of MRI scan. MRI scan was expected to complete in not more than 3 hours.