1. Serial arteriograms show not only the anatomical distribution of blood vessels but also the functional state and activity of the peripheral circulation. The technique is of value in the diagnosis of tumours of soft tissues and bone, and particularly in the differential diagnosis of bone tumours from chronic osteomyelitis. It may be used to assess the response of malignant bone tumours to treatment by irradiation.

2. In malignant bone tumours, serial arteriograms show irregular formation of new vessels of uniform diameter, "blood pools," and increased rapidity of flow from the arterial to the venous systems.

3. In osteoclastomas there is new vessel formation and an appearance of "blood pools," but less rapid filling of the veins. In simple tumours there is no new formation of vessels. The tumour itself is often relatively avascular.

4. In osteomyelitis there is no new formation of vessels but only dilatation of existing vessels. The vessels retain their orderly and regular arrangement of successive branches of gradually decreasing diameter.