ASQ-3 scores are sensitive to small differences in age in a Peruvian infant population.

OBJECTIVE: The Ages and Stages Questionnaires Edition 3 (ASQ-3) are a well-validated international screen for developmental delays in young children. However, previous studies demonstrate variable scores between children eligible to take the same ASQ-3 interval. This study aimed to determine a relationship between age and ASQ-3 score for each screening interval. METHODS: This was a baseline exploratory cross-sectional study of infants under 2 years old evaluated for the Peruvian social programme Cuna Más. Participants were included in Cuna Más if they lived in districts with fewer than 2000 inhabitants or 400 homes, indicating a predominantly rural population. The appropriate ASQ-3 screening interval was administered to each subject. Subjects were divided into four 2-week chronological subgroups based on age within each 2-month screening window and aggregated across all 12 screening intervals. Fisher's exact test, analysis of variance and Bonferonni post hoc test were used to compare differences between age subgroups. Linear regression was performed to assess the relationship between ASQ-3 score and both aggregated and disaggregated age subgroup. RESULTS: A total of 5850 Peruvian infants were evaluated in 2013. Mean age was 13 ± 6.6 months, 50.7% were male and mean maternal education was 6.6 ± 4.0 years; 34.8% infants were stunted, 7.8% were underweight, 0.9% were wasted and 2% had age adjusted greater than 35 days for prematurity for ASQ-3 interval assignment. Mean total ASQ-3 was 42.2 ± 8.2. The ASQ-3 allocated 49.6% with suspected delay in one or more developmental areas. Before and after adjusting for wealth quintile, maternal education level, infant nutritional status and prematurity adjustment, age subgroup remained significantly associated with total ASQ-3 score (ß = 1.8, CI: 1.7-2.0, P < 0.001), sectional ASQ-3 score (all P < 0.001) and inversely associated with one or more scores indicating suspected developmental delay (P < 0.001). CONCLUSIONS: The ASQ-3 may underestimate the sensitivity of child development to small differences in age in this population.

Real-time 3D motion tracking for small animal brain PET.

High-resolution positron emission tomography (PET) imaging of conscious, unrestrained laboratory animals presents many challenges. Some form of motion correction will normally be necessary to avoid motion artefacts in the reconstruction. The aim of the current work was to develop and evaluate a motion tracking system potentially suitable for use in small animal PET. This system is based on the commercially available stereo-optical MicronTracker S60 which we have integrated with a Siemens Focus-220 microPET scanner. We present measured performance limits of the tracker and the technical details of our implementation, including calibration and synchronization of the system. A phantom study demonstrating motion tracking and correction was also performed. The system can be calibrated with sub-millimetre accuracy, and small lightweight markers can be constructed to provide accurate 3D motion data. A marked reduction in motion artefacts was demonstrated in the phantom study. The techniques and results described here represent a step towards a practical method for rigid-body motion correction in small animal PET. There is scope to achieve further improvements in the accuracy of synchronization and pose measurements in future work.