Compression Storage and Communication

46 Fundamentals and Standards of Compression and Communication

Stephen P. Yanek, Quentin E. Dolecek, Robert L. Holland, and Joan E. Fetter 759

47 Medical Image Archive and Retrieval Albert Wong and Shyh-Liang Lou 771

48 Image Standardization in PACS Ewa Pietka 783

49 Quality Evaluation for Compressed Medical Images: Fundamentals

Pamela Cosman, Robert Gray, and Richard Olshen 803

50 Quality Evaluation for Compressed Medical Images: Diagnostic Accuracy

Pamela Cosman, Robert Gray, and Richard Olshen 821

51 Quality Evaluation for Compressed Medical Images: Statistical Issues

Pamela Cosman, Robert Gray, and Richard Olshen 841

52 Three-Dimensional Image Compression with Wavelet Transforms

Jun Wang and H.K. Huang 851

H.K. Huang

Childrens Hospital of Los Angeles/University of Southern California

This section presents the fundamentals and standards that form the basis of medical image archiving and telemedicine systems. Seven chapters are included. The first chapter (46) introduces the basic concepts and standards of image compression and communication, including JPEG and MPEG, as well as the potential contributions of wavelets and fractals. The chapter also describes the essentials of technologies, procedures, and protocols of modern telecommunications systems used in medicine.

The second chapter (47) discusses medical image archiving, retrieval, and communication. The structure and function of Picture Archiving and Communication Systems (PACS) are described. The de facto DICOM (digital image communications in medicine) format, communication standards for images, as well as the HL-7 (Health Level 7) format for medical text data, are introduced. The DICOM image query and retrieve service class operations are also addressed.

The third chapter (48) presents a suggested standard imposed by users according to their needs in clinical practice. Since the type of users can be diverse, the format and content of the data vary and may include diagnostic images, medical reports, comments, and administrative reports. This chapter focuses on the adjustment of the image content in preparation for medical diagnosis, and provides recommendations for adoption of such image standardization in PACS.

The other four chapters focus on medical image compression with lossy techniques. Chapters 49, 50, and 51 discuss quality evaluation for lossy compressed images, addressing fundamentals, diagnostic accuracy, and statistical issues. Topics that include average distortion, signal-to-noise ratio, subjective ratings, diagnostic accuracy measurements, and the preparation of a gold standard are covered in Chapter 49. Chapter 50 provides examples to illustrate quantitative methods of evaluation of diagnostic accuracy of compressed images. These include lung nodules and mediastinal adenopathy in CT images, aortic aneurysms in MR images, and mammograms with microcalcifications and masses. Chapter 51 addresses the statistical basis of quality evaluation. Topics including differences among radiologists, effectiveness of the experimental design, relationship of diagnostic accuracy to other measures, statistical size and power, effects of learning on the outcomes, relationship between computed measures and perceptual measures, and confidence intervals are discussed.

Chapter 52 in this section reviews the methodology used in 3D wavelet transforms. The basic principles of 3D wavelet transform are first discussed and the performance of various filter functions are compared using 3D CT and MRI data sets of various parts of the anatomy.

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