Staging of musculoskeletal tumors

Staging of musculoskeletal neoplasms is important for planning chemotherapy and surgical procedures. Accurate staging has increased in importance with advancements in limb salvage procedures. This article outlines concepts, techniques, and potential problems with staging of neoplasms. It is important to remember that biopsy should be preformed after consultation with an orthopedic surgeon specialized in tumor surgery.

Radiologic case study. Macrodystrophia lipomatosa

Macrodystrophia lipomatosa is a rare form of gigantism involving an extremity consisting of predominately fibroadipose tissue. Radiographically, it appears as hypertrophy of soft tissues and bone. CT and MR scanning delineate the tissues involved and are virtually diagnostic, demonstrating the predominantly adipose component as well as the overgrowth of the bones, nerves, and vessels also involved.

Magnetic resonance imaging of the nose with surface coils: a new technique to evaluate functional and aesthetic problems

Determining the preoperative functional and aesthetic anatomy has been of critical importance to surgeons planning nasal procedures. Beyond skilled clinical examination, few objective studies exist to aid the surgeon. Magnetic resonance imaging (MRI) represents a potentially excellent method for precise anatomic imaging of the nose. Unlike computed tomography (CT) and conventional x-rays, MRI involves no radiation. Similar to CT, however, MRI can provide computer-enhanced three-dimensional and quantitative airway data. Full-head MRI has proven sensitivity in evaluation of tumors of the brain and sinuses and is the imaging modality of choice for many soft-tissue tumors. Due to the relatively high cost of conventional full-head MRI scanning ($600 to $1200 per scan), MRI of the nose utilizing full head scanning technique has been limited. The recent development of small field of view surface coils has enabled higher-resolution nasal scans at a fraction of the scanner time and cost ($200 to $500) of conventional MRI scans. We have developed a protocol utilizing a small field of view coil which results in reproducible high-resolution nasal scans requiring less than 6 minutes of scanner time. This protocol has been used in both the diagnosis and follow-up of patients with traumatic and congenital nasal and septal deformities. Image resolution obtained using the protocol is significantly better than with conventional coils. This technique is excellent for both diagnosing and documenting nasal anatomy and pathology.

Scanning electron-microscopic and magnetic resonance-imaging studies of injuries to the patellofemoral joint after acute transarticular loading

To examine the effects of transarticular loading on articular cartilage and subchondral bone, we used a canine model that we had developed previously, in which a standardized load of approximately 2000 newtons is delivered across the patellofemoral joint. The purpose of the study was to define and describe the initial changes, as seen on histopathological and magnetic resonance-imaging studies, that occur in the early stages after injury to the joint by transarticular loading. Scanning electron microscopy was used to define the extent and characteristics of the fractures produced in the subchondral bone of four patellae that were examined on the day of loading. We found multiple, extensive fractures through the zone of calcified cartilage and the subchondral bone, frequently with step-off displacement, and with little or no change in the gross appearance of the articular cartilage. Specimens from four patellae were examined histologically two weeks after loading, and the observed changes were correlated with those that had been demonstrated by scanning electron microscopy. Fractures through the zone of calcified cartilage and the subchondral bone, with step-off displacement, were prominent. Clefts were present in the surface of the articular cartilage and, in some areas, there was a focal loss of proteoglycan from the extracellular matrix, as indicated by the complete absence of staining with safranin O. Six dogs were examined one year after loading. There was healing of the subchondral fractures and restoration of proteoglycan in the extracellular matrix. However, superficial clefts and fissures were still present in the articular cartilage. Sequential magnetic resonance-imaging studies were also carried out on these six dogs, at two, eight, sixteen, thirty-six, and fifty-two weeks after loading. Two weeks after loading, all knees had soft-tissue swelling, effusion, and a decreased marrow signal in the medullary cavity of the patella. The decreased marrow signal and effusion were still present eight weeks after the impact, and then the findings gradually returned to normal. One year after loading, it was found that the histopathological changes had not been progressive; in fact, they had been ameliorated and, to some extent, reversed by repair processes. The early, severe magnetic resonance-imaging changes had also been reversed, so that this study demonstrated normal findings by one year after loading.

The use of MRI in the diagnosis of benign and malignant bone and soft tissue tumours

Two hundred and thirty four suspected primary bone and soft tissue tumours were investigated using plain films and MRI. The MR appearance of 200 of these tumours was assessed with respect to the intensity of the lesion, the homogeneity of the tumour, the presence or absence of a capsule or lobulation, whether the tumour was whorled or not and whether it contained either fluid or blood. Apart from benign lipomas and some malignant myxoid liposarcomas, however, it seemed virtually impossible to tell one tumour from another and in many cases to differentiate a benign lesion from a malignant tumour using MRI alone. We recommend that the workup of a suspected soft tissue tumour should be initially by MR scanning and that the workup of a suspected malignant bone tumour should be plain films followed by an MRI scan.

Radiologic case study. MRI in the diagnosis of synovial disease

Fourteen patients with various synovial diseases were imaged using conventional radiographic techniques and MRI. We had five patients with synovial tumors, including two each with PVNS and synovial osteochondromatosis. We had five patients with infections and four patients with various other forms of arthritis. Although MRI was found to be a useful means to visualize the synovium, the findings were nonspecific except in the case of PVNS.

Peripheral (extracranial) nerve tumors: correlation of MR imaging and histologic findings

Magnetic resonance (MR) images of 16 peripheral nerve tumors (14 patients) were correlated with histopathologic appearance. Thirteen patients had surgically proved neuro-fibromatosis. There were 10 neurofibromas, four schwannomas, and two neurofibrosarcomas. Seven of the 10 neurofibromas showed a target pattern of increased peripheral signal intensity and decreased central signal intensity on T2-weighted images. This pattern appeared to correspond to a distinctive zonal histologic appearance that was found only in the neurofibromas. This pattern was not seen on MR images of the other peripheral tumors.

Bursitis in association with solitary osteochondromas presenting as mass lesions

Three patients with solitary osteochondromas which were increasing in size have been recently examined. Plain films were available on all patients; two patients had MR studies, and two had CT scans. In all three cases, malignant transformation of the osteochondroma was suspected from the cross-sectional imaging studies, but pathologic examination proved that these patients all had bursa formation without any evidence of malignancy. The incidence of this rare complication of solitary osteochondroma is discussed. Ultrasound is also recommended for the evaluation of enlarging solitary osteochondromas.

Imaging in orthopedic surgery and other conditions of the musculoskeletal system

Interest continues in total joint replacement and its complications. Now that noncemented arthroplasties have been introduced, further radiographic signs are being elucidated. The roles of bone scanning and aspiration arthrography are also being reevaluated. Ultrasonography has become the imaging modality of choice in congenital hip dysplasia and is being used increasingly in the evaluation of other musculoskeletal conditions. The ilizarov distraction osteogenesis technique is also discussed and there has been increasing interest in anterior cruciate ligament reconstruction and its sequelae.

Case report 703: Multifocal osteosarcoma

There are two theories concerning the origin of multifocal osteogenic sarcoma: In one, the lesions all arise synchronously as multiple, simultaneously appearing, primary tumors, and in the other, there appears to be one dominant site with early and rapidly progressive metastatic disease. We believe that our patient fits into the second group with a primary right (distal-end) femoral osteogenic sarcoma with early and rapid metastasis. Bone scan, chest CT, and MRI examinations played an essential role in the initial evaluation and follow-up of this patient with osteosarcomatosis. The multiple modalities also offered a greater sensitivity in the detection and for the surveillance of the progression of the condition.

Cortical thickness and trabecular pattern of the femoral neck as a measure of osteopenia

The pelvic radiographs of 312 patients aged 18 to 92 years were reviewed to determine if the Singh index was valid or not. The cortical thickness of the lower part of the femoral calcar, the stress index (body weight, physical activity, and femoral neck angle), and the Singh Index (trabecular pattern of the femoral neck) were measured in each patient and correlated with each other and with the patient's age, sex, and dominant side. It was found that the Singh index correlates well with age but not with the cortical thickness or stress index. Thus, the Singh index is an unreliable measure of osteopenia, and we conclude that other methods should be used for screening patients with osteoporosis.

Open meniscus repair. Technique and two to nine year results

An average 4.6 year follow-up study has been done on 80 of 104 open meniscus repairs of unstable peripheral tears. Two of nine retears were treated in the acute stage and seven were treated in the chronic stage. Eight retears were medial, one was lateral (repair ratio, 1.5:1 medial to lateral), three occurred through the repair site, and six occurred in different areas. Retears occurred in 1 of 26 isolated repairs, 2 of 38 repairs done with an ACL stabilization procedure, and 6 of 16 repairs done in ACL deficient knees that were not stabilized. Standing radiographs revealed normal compartments in 40 of 41 repairs.