You may be able to find some longitudinal data sets at The Cancer Imaging Archive: https://www.cancerimagingarchive.net/ https://www.cancerimagingarchive.net/ (

You may be able to find some longitudinal data sets at The Cancer Imaging Archive: https://www.cancerimagingarchive.net/ https://www.cancerimagingarchive.net/ (some are also already preloaded into Google Cloud buckets: https://cloud.google.com/healthcare/docs/resources/public-datasets/tcia https://cloud.google.com/healthcare/docs/resources/public-da...)