Use scan- or subject-wise hematocrit values, when available, to calculate T1blood

[tsalo]

Summary

I was reading Juttukonda et al. (2021), and they calculate T1blood on an individual basis using hematocrit, per Lu et al. (2004). When hematocrit isn't available, a value based on participant age and sex can be used, per Mahlknecht and Kaiser (2010). The Lu formula is 3T-specific, so we may need to find versions for other field strengths.

Additional details

The hematocrit, age, and sex information may be available in tabular files (e.g., the participants file, or scants.tsv files) in the dataset.