We present the Queensland Twin IMaging (QTIM) dataset: a multimodal neuroimaging dataset of young adult twins and siblings (18-30 years, N = 1026), including a subsample of participants, scanned a second time to assess test-retest reliability (N = 78, test-retest interval ~ 3.5 months). The QTAB dataset additionally includes adolescent twins scanned at age 12 (N = 88) or 16 (N = 88) years. Approximately a third of these 12- and 16-year-old participants were scanned four years later as part of a longitudinal pilot study (scanned at 12 and 16 years N = 24, scanned at 16 and 20 years N = 38). Scanning parameters and acquisition details are detailed elsewhere (see "How to Acknowledge"). 

Data Record

Basic demographic data (age [rounded down], sex, handedness, family_id [to denote non-independent participants]) is provided at the top-level of the dataset directory in participants.tsv (variables and properties described in participants.json). Zygosity and limited non-imaging phenotypic data are available for QTIM participants. A data transfer agreement and institutional ethics approval are required for access; for more information, please contact Dr Lachlan Strike, QIMR Berghofer Medical Research Institute (lachlan [dot] strike [at] qimrberghofer [dot] edu [dot] au). Cortical and subcortical brain measures extracted using FreeSurfer v5.3 are provided under derivatives/freesurfer_5.3. The extraction and quality checking of these measures is detailed in Strike et al., 2019 (see "How to Acknowledge"). Hippocampal subfield measures extracted using Freesurfer v6 (using the base reconstruction from FreeSurfer v5.3) are also provided.
MRIQC image quality metrics (IQMs) for T1w images are provided under derivatives/mriqc as are DSI Studio quality metrics for dwi images.

Usage Notes

Due to a scanner software upgrade, the QTIM T1w sequence was modified during data collection (slice number decreased 256 to 240,  acquisition orientation changed from a coronal (80% of participants) to a sagittal (20% of participants) direction). This change is indexed by the "ses01_T1w_acq" and "ses02_T1w_acq" variables in "participants.tsv". Please note that a prominent vascular pulsation artefact in the T1w images varies with the acquisition orientation. Investigators should consider whether a statistical adjustment is sufficient to control these effects or whether participants should be restricted to a single acquisition orientation.

The onset of the n-back task was delayed such that the first trial was coincident with the 6th volume acquired. As such, the initial 5 volumes of the n-back scan should be removed to ensure that steady-state tissue magnetization was reached. In the 12-year-old participant subsample, the n-back stimulus presentation time was increased to from 1 to 1.5 seconds midway through the project (younger participants had difficulty with the 1 sec presentation). The "nback_seq" variable in "participants.tsv" denotes whether 12-year-old participants completed the 1 or 1.5 second n-back task.