A radiologist sends you a 250MB PDF containing a series of MRI images for a second opinion. Your email rejects it. The patient portal has a 100MB limit. The secure messaging app times out.
Medical imaging PDFs need careful compression — too aggressive and diagnostic detail is lost.
Understand what's in the PDF
Imaging PDFs typically contain rendered DICOM views — not the original DICOM data. The PDF is already a lossy representation. Compressing further removes information that may be diagnostically relevant. Before compressing, ask whether DICOM share via PACS would be preferable for diagnostic purposes — PDFs are usually for record-keeping and second opinions where coarse review is enough.
Conservative compression
Use compress PDF at the lightest setting that brings the file under your channel's size limit. Aggressive compression that's fine for a property listing introduces visible degradation on imaging. Test on a representative image — if anatomical edges become fuzzy, dial back.
Split where compression isn't enough
If the file remains too large after compression, split PDF into sections (e.g. by anatomical region or by series). Multiple smaller PDFs are easier to share than one over-compressed monster. Reference between files using a clear naming convention.
Consider the receiving clinician
The compressed PDF needs to be useful for the clinician opening it. A second opinion from a colleague benefits from full detail; a routine record transfer can tolerate more compression. Match the compression level to the clinical purpose.
FAQ
Will compression affect diagnostic quality?
Aggressive compression can. For diagnostic review, prefer DICOM via PACS or minimal PDF compression. For record-keeping, moderate compression is fine.
What's a safe compression level for imaging?
Flint's lightest compression preset typically cuts size by 30-50% without visible quality loss. Aggressive compression can lose anatomical detail.
Should I compress before or after merging multiple studies?
Merge first, then compress the combined file. Compressing each input separately and then merging compounds losses.
Is there a maximum file size for diagnostic PDFs?
No clinical maximum, but practical channel limits (email, portals) typically cap at 25-100MB. Above this, use DICOM transfer.
Compress for the channel, not for the sake of it. Compress conservatively in Flint and diagnostic detail survives.