The diagnosis, treatment planning, and follow-up evaluation of osteosarcoma rely heavily on a variety of imaging techniques. Plain roentgenography, radionuclide bone scanning, computed tomography, and magnetic resonance imaging play important roles in defining local tumor extent, detecting metastatic disease, and monitoring for recurrent tumor. Invasive studies such as angiography are now rarely necessary. In the future, newer imaging modalities, including positron emission tomography, can be expected to become important tools for evaluation of these tumors.

Appropriate imaging and clinical examinations may lead to early diagnosis and treatment of the shoulder impingement syndrome, thus preventing progression to a complete tear of the rotator cuff. In this article, we discuss the anatomic and pathophysiologic bases of the syndrome, and the rationale for certain imaging tests to evaluate it. Special radiographic projections to show the supraspinatus outlet and inferior surface of the anterior third of the acromion, combined with magnetic resonance images, usually provide the most useful information regarding the causes of impingement.

Osteoarthritis may be divided into primary generalized and secondary forms. Primary generalized osteoarthritis is characterized by narrowing of cartilage, marginal osteophytes, and absence of erosions. The most common sites of involvement are the distal interphalangeal joints of the fingers and the first carpometacarpal joint. Secondary osteoarthritis also results in narrowing of cartilage in the absence of erosions, but in regions of mechanical stress. Erosive osteoarthritis affects predominantly the proximal and distal interphalangeal joints, and evolves into bony fusion in 12 to 15 per cent of cases, about the same percentage of interphalangeal bony fusion that occurs in psoriatic arthritis. Ankylosing spondylitis predominates in the axial skeleton where it eventually leads to fusion of the vertebrae and sacroiliac joints. Psoriatic arthritis combines many features of rheumatoid arthritis, in which synovial inflammation predominates, and ankylosing spondylitis, in which ligamentous inflammation predominates. The hands and feet are involved to an equal extent, and in 20 per cent of patients the disorder also involves the sacroiliac joints and spine. Reiter's disease, like psoriatic arthritis, differs from ankylosing spondylitis in its inconstant involvement of the spine and greater involvement of peripheral joints. Reiter's disease differs from psoriatic arthritis in its predominant involvement of the lower limbs, particularly the feet, with relative sparing of the hands and wrists. Multicentric reticulohistiocytosis is a rare disorder in which polyarthritis usually precedes the onset of nodular cutaneous eruptions, a fact that emphasizes the importance of early roentgenologic recognition. The interphalangeal joints are the predominant sites of involvement in the hands, but eventually all of the synovium lined joints become affected, with arthritis mutilans the end result in one third of cases. The erosions are strikingly symmetrical and well circumscribed, and accompanying osteoporosis is disproportionately mild. Progressive systemic sclerosis is characterized by atrophy and dystrophic calcifications in the soft tissues, ultimately leading to joint deformities and resorption of the terminal tufts of the phalanges. Resorption of bone occurs at other sites as well, and marginal erosions may develop in the metacarpophalangeal and interphalangeal joints of the hands.

Although magnetic resonance (MR) imaging is highly sensitive for the detection of abnormalities of the musculoskeletal system, changes in marrow and soft-tissue signal intensity are often nonspecific, and benign conditions may be mistaken for malignancy. In an effort to identify the cause of this type of misdiagnosis in MR examinations, the MR scans were reviewed of 30 patients whose images manifested bone and/or soft-tissue changes that were initially believed to be consistent with malignancy but were later found to represent benign conditions. Of the 30 patients, MR abnormalities were attributable to trauma in 11, benign tumors and tumorlike conditions in ten, infection in seven, and prior radiotherapy in two. In 24 cases, correlative imaging studies (14 patients), appropriate clinical history (six patients), and/or physical and laboratory examinations (four patients) would have avoided these misdiagnoses.

Objective

This article discusses how ribs are involved in a variety of traumatic, metabolic, inflammatory, neoplastic, and congenital disorders.

Conclusion

We review the normal anatomy pertinent to rib imaging and illustrate the key features of a variety of rib lesions, emphasizing the diagnostic value of CT.

Early and accurate diagnosis of infection or neuropathy of the diabetic foot is the key to successful management. Angiopathy leads to ischemia which, in combination with peripheral neuropathy, predisposes to pedal skin ulceration, the precursor of osteomyelitis. Chronic hyperglycemia promotes production of glycosylated end products which accumulate on endothelial proteins, causing ischemia of the vasa nervorum. When combined with axonal degeneration of the sensory nerves, the result is hypertrophic neuroarthropathy. Should the sympathetic nerve fibers also be damaged, the resultant loss of vasoconstrictive impulses leads to hyperemia and atrophic neuroarthropathy. Plain radiography, although less sensitive than radionuclide, magnetic resonance (MR), and computed tomographic examinations, should be the initial procedure for imaging suspected osteomyelitis in the diabetic patient. If the radiographs are normal but the clinical suspicion of osteomyelitis is strong, a three-phase 99mTc-MDP scan or MR imaging is recommended. An equivocal 99mTc-MDP scan should be followed by MR imaging. To exclude osteomyelitis at a site of neuroarthropathy, a 111In white blood cell scan is preferable. To obtain a specimen of bone for bacteriological studies, percutaneous core biopsy is the procedure of choice, with the entrance of the needle well beyond the edge of the subjacent ulcer.