Problem is though for most of these diseases there just aren't the number of samples available, period, to do it the "right way". HCC for example, has around 50K new cases/year in the US. Even if every single case went into a repository with perfect labels, would still take a long time to collect that info. Not to mention you need either a radiologist (4 year of medical school + 6 years of post-school training) or a very skilled and experienced technician to label the data.
Not to mention imaging protocols are not standardized, and the imaging technology is also evolving so scans we do today may not be "correct" or standard in 5-10 years.