How do I find the extents of my data in an Excel file (.XLSX) using EPPlus?

Question

Given an Excel spreadsheet, how do I find the extents of the data? Is there a method I can call or a property I can check? Do I need to check cell-by-cell for nulls and then row-by-row? There's gotta be an easier way, right?

I just downloaded the EPPlus library this morning so I might be overlooking something basic. I also checked the sample project but didn't see anything related to this question in it.

Thanks!