The value of imaging in the diagnosis and treatment of bone tumors.

The authors report their experience in the diagnosis of bone tumors at the Rizzoli Institute of Bologna. The main imaging techniques used to this purpose are conventional radiography, CT, MRI, and isotope bone scan. Angiography is rarely used. Conventional radiography is the examination of choice and is sufficient in several benign lesions not requiring treatment. Supplementary imaging studies are usually needed when radiographic findings are questionable and/or the lesion requires treatment. When a biopsy is required, it should be carried out after a complete imaging work-up, which sometimes allows a correct prebiopsy diagnosis, indicates the biopsy modality, approach and site, and is also mandatory to stage the tumor, plan the surgical approach and technique, and show in the finest details the occult tumor spread. CT best shows mineralized tissues and pulmonary metastases. It is also frequently used as a guide for needle biopsies. MRI beautifully shows the different tissues and compartments and it is particularly sensitive in depicting fat. Moreover, it can be repeated many times, even in pregnant women, because it needs no ionizing radiations and iodinated contrast; it is also free of artifacts in the patients with orthopedic devices which are usually nonferromagnetic. However, the execution of an adequate MRI requires experience and knowledge of bone pathologic conditions. Bone scan helps in detecting any 'active' area in the bone. It can be thus useful to depict lesion quiescence or activity and to stage any tumor which can metastasize to the skeleton. Bone scan is also helpful to show bone lesions when they are not visible on plain radiographs and indicates the tumor response to preoperative chemotherapy. Angiography is helpful when a preoperative selective embolization is needed, or when complex vertebral surgery or vascular surgery are planned. The bad outcome of bone tumors often depends on incomplete, inadequate or misinterpretated imaging findings.