Pediatric Catheter-related Thrombosis Imaging Study

One set of 3 diagnostic imaging procedures (US, MRI with contrast, and MRI without contrast) was performed for all cohorts. Imaging was performed on Visit 1, which in Cohort A was Day 40 ± 20 days from Day 0, the placement of the central venous catheter (CVC), or if possible within 72 hours after a CVC was removed or lost; Visit 1 in Cohort B was within 7 days of initiation of symptoms of a CVC-related deep vein thromboembolism (DVT) or within 7 days of an incidental diagnosis of CVC-related DVT by radiographic imaging. Cohort C participants had an ultrasound done within 48 hours of the performance of the MRI, which was scheduled for a clinical reason. Note: participants completing each MRI procedure (with contrast or without contrast) could be different participants.

Imaging was performed on Visit 1 which was defined for Cohort A as: Day 40 ± 20 days from Day 0, the placement of the central venous catheter (CVC), or if possible within 72 hours after a CVC was removed or lost; Visit 1 defined for Cohort B: within 7 days of initiation of symptoms of a CVC-related deep vein thromboembolism (DVT) or within 7 days of an incidental diagnosis of CVC-related DVT by radiographic imaging. Cohort C participants had an ultrasound done within 48 hours of the performance of the MRI. All 3 imaging procedures, ultrasound, MRI with contrast, MRI without contrast were to be performed on all participants, regardless of the cohort.

One set of diagnostic imaging procedures (US and MRI) was to be performed for all cohorts The MRI consisted of MRI venous imaging without contrast enhancement and MRI venous imaging with contrast enhancement.

Bilateral US was attempted but if it could not be completed, a unilateral US was accepted for analysis. Participants who did not complete the MRI procedure with contrast could be different participants from those who did not complete the MRI procedure without contrast. Primary reasons for non-completion of imaging included: technical, investigator decision, child refused, parent refused, child missed appointment, difficulties with anesthesia/sedation, child unable to lie still, problems with contrast administration, and other reasons. Other reasons could include: late to appointment and unable to perform MRI due to time constraints; logistical reasons, parent agreed to only ultrasound at time of consent, schedule delay, equipment not available, difficulty putting patient in correct position. Due to the small numbers of participants in some cohorts, these data were more meaningful with all cohorts grouped together for the total imaged population.

MRI with contrast (c) and without (w/o) contrast (c) enhancement were performed and a US was done within 48 hours of the MRI. Once detected, the DVT was adjudicated and confirmed by an independent central adjudication Committee (ICAC) consisting of experienced physicians not involved in the study and blinded to each participant's identity and clinical course. Participants were considered positive for DVT if at least one of the radiographic procedures was positive. Cohort A: Day 0=day of catheter placement; Day 40 (± 20 days)=day of imaging procedures at Visit 1, or if possible within 72 hours after a CVC is removed or lost. Cohort B Visit 1: within 7 days of initiation of symptoms of a CVC-related DVT (symptoms include but were not limited to: redness, pain/tenderness, swelling, presence of subcutaneous collaterals, catheter occlusion, and the presence of catheter related infection) or within 7 days of an incidental diagnosis of CVC-related DVT by radiographic imaging.

Adjudication was by an Independent Central Adjudication Committee (ICAC) consisting of experienced physicians not involved in the study and blinded to each participant's identity and clinical course. One set of 3 study-related diagnostic imaging procedures (US, MRI with contrast, and MRI without contrast) was performed. Participants were considered positive for DVT if at least one of the radiographic procedures was positive.

Adjudication was by an ICAC consisting of experienced physicians not involved in the study and blinded to each participant's identity and clinical course. One set of Study-related diagnostic imaging procedures (US, MRI with contrast, and MRI without contrast) was performed for all cohorts. Participants were considered positive for DVT if at least one of the radiographic procedures was positive.

Signs and symptoms of PE include shortness of breath, pleuritic pain, cough, orthopnea, wheezing, and may have associated signs and symptoms of DVT. In the event a PE was detected while undergoing the study MRI or other imaging procedure required for care of an underlying condition, and the participant did not manifest any signs and/or symptoms of a PE, the event was considered an asymptomatic PE. The participant was managed and further investigated according to the investigator's standard of care. All diagnostic imaging procedures performed, such as contrast-enhanced computer tomography (CT) pulmonary angiogram, nuclear ventilation perfusion lung scan (V/Q scan), were submitted for adjudication as a suspected PE.

Death as an endpoint in a participant with an adjudicated venous thromboembolism (DVT or PE) was summarized, regardless of the cause of the death. The VTE was adjudicated by a blinded central independent adjudication committee.