Compression of Digital Images in Radiology - Results of a Consensus Conference

Purpose: Recommendations for lossy compression of digital radiological DICOM images in Germany by means of a consensus conference. The compression of digital radiological images was evaluated in many studies [1-5], Even though the results demonstrate full diagnostic image quality of modality-dependent compression between 1:5 and 1:200, there are only a few clinical applications. Materials and Methods: A consensus conference with approx. 80 interested participants (radiology, industry, physics, and agencies) without individual invitation was organized by the working groups AGIT and APT of the German Roentgen Society DRG to determine compression factors without loss of diagnostic image quality for different anatomical regions for CT, CR/DR, MR, RF/XA examinations. The consent level was specified as at least 66%. Results: For individual modalities the following compression factors were recommended: CT (brain) 1:5, CT (all other applications) 1:8, CR/DR (all applications except mammography) 1:10, CR/DR (mammography) 1:15, MR (all applications) 1:7, RF/XA (fluoroscopy, DSA, cardiac angio) 1: 6. The recommended compression ratios are valid for JPEG and JPEG 2000/Wavelet compressions. Conclusion: The results may be understood as recommendations and indicate limits of compression factors with no expected reduction of diagnostic image quality. They are similar to the current national recommendations for Canada and England [21, 27].