Magnetom trio 3t scanner

Imaging data were collected on a Siemens MAGNETOM Trio 3T scanner as described in a previous publication (Gullett et al, 2018 (link)). Briefly, whole-brain T1-weighted images were collected in 255 interleaved axial 1-mm slices with TR=1.90 s, TE=2.98 s, and field of view=256×256 mm. Structural T1 images were processed using the Freesurfer automated pipeline (Fischl et al, 2002 (link)). Whole-brain DTI were collected in 69 interleaved axial 2-mm slices with TR=1.10 s, TE=103 ms, and field of view=128×128 mm. Diffusion data were collated into a dataset with 64 b=1000m/s² volumes, 10 b=5 mm/s² volumes, and 1 b=0 volume, for a total of 75 volumes per scan.

MRI data were acquired using a Siemens Magnetom Trio 3T scanner. Two MPRAGE structural sequences were acquired (192 axial slices with isotropic spatial resolution of 0.9 mm) for registering each participant’s functional data to standard space while participants completed the practice block and were averaged together to increase the signal-to-noise ratio. Gradient field-maps were collected to correct for distortions caused by magnetic field inhomogeneities in the functional data (Jezzard & Balaban, 1995 (link)). During each of the three task blocks, 331 functional imaging volumes were collected using a Siemens gradient echo-planar imaging sequence (repetition time [TR] 3000 ms, echo time [TE] 25 ms, flip angle 90°, field of view [FOV] 256 mm). Each image consisted of 50 oblique axial slices (slice thickness 2.40 mm, in-plane voxel size 2.13 mm x 2.13 mm) acquired parallel to the plane containing the anterior and posterior commissures. Three volumes at the beginning of each task block were discarded to allow the scanner to reach steady state.

Infant medical records were obtained and a medical risk index score (range: 0–10) was created from dichotomized (present= 1, absent= 0) factors: intrauterine growth restriction, did not receive antenatal steroids, received dexamethasone, oxygen at 36 weeks, necrotizing enterocolitis, confirmed sepsis, patent ductus arteriosus, retinopathy of prematurity, ≥3 standard deviation (SD) decrease in weight-for-height/length from birth to term-equivalent age, and >75^th percentile for duration of parenteral nutrition.^{11 (link)} Based upon previous findings in this cohort,^{21 (link)} NICU room type (private room or open ward) was also examined as a potential covariate of interest. VPT infants underwent magnetic resonance imaging (MRI) at term-equivalent postmenstrual age using a Siemens Magnetom Trio 3T scanner with previously documented sequences.^{22 (link)} MRI images were qualitatively scored for the presence and severity of cystic lesions, focal signal abnormality, myelination delay, thinning of the corpus callosum, lateral ventricle dilatation, and cerebral volume reduction.^{23 (link)} Total WMA scores (range: 0–15) were categorized into none (0–2), mild (3–4), moderate (5–6), and severe (≥7).^{23 (link)} Mothers reported the use of physical, occupational or speech/language intervention services from birth to 5 years on a customized questionnaire.

Resting state fMRI (6 minutes; 180 volumes) and high resolution T1 scans were acquired on a Siemens Magnetom Trio 3T scanner, followed by standard preprocessing in SPM8 and connectivity analyses in the CONN toolbox (see Supplemental Materials) ^{50 (link)}. Participants were excluded if they exceeded absolute thresholds for translation (3mm) or framewise displacement (FD; more than 1/3 of the time series exceeding 0.5mm FD) ^{9 (link),51 (link)}. Within the BI and BN groups, the included versus excluded participants did not significantly differ (p's > 0.20) in age, sex, BIQ scores (Total, Social novelty, or Situational novelty scales), social phobia symptoms, or IQ (block design, vocabulary, or full scale).