In the departments of Rehabilitation, Biomedical Physics and Technology, and Anatomy research and clinics of the musculoskeletal system fonn the centre of attention. In this field pathologies related to low back pain and hand and wrist are under investigation. In both areas some quantitative assessments for diagnosis, treatment and follow-up can not be done with existing routine techniques. For normal examination procedures many means are available. Examples of clinical examinations are Laseque; imaging techniques, e.g. X-rays, CT and MRI; functional laboratory techniques e.g. dynamometry and EMG, and special facilities like bone traction. In the study on low back pain special interest raised for the mechanical properties oftlIe pelvic joints, in particular the sacroiliac (SI) joints. For the assessment of SI joint stifthess no instrumented method was available. In the study 011 the hand and wrist pathology no method was available to measure non-invasively the function of the tendons. While searching for solutions we discovered that Colour Doppler Imaging (CDI) opened flew possibilities in the research of the musculoskeletal system in general, and for our research interests in particular. In the following paragraphs a general introduction is given on the existing routine use of CD!. Further, application on the assessment of SI joint stiffness, and hand and wrist pathologies is introduced in separate sectors which give a brief overview of the chapters of this thesis. The general aim of this study is to extend the application of CDI in the field of the musculoskeletal system.