Search

Purpose: To review the imaging appearance of periosteal osteosarcoma, with pathologic comparison., Materials and Methods: Data for 40 pathologically confirmed periosteal osteosarcomas were retrospectively reviewed. Patient demographic data were recorded, and radiographs (n = 40), bone scintigrams (n = 10), angiograms (n = 2), and computed tomographic (CT) (n = 11) and magnetic resonance (MR) (n = 12) images were evaluated for lesion location and size, cortical changes, marrow involvement, and intrinsic characteristics by two musculoskeletal radiologists, with agreement by consensus. Pathology reports were reviewed for presence and predominance of histologic components (fibrous, chondroid, and osteoid), tumor grade, and marrow involvement., Results: There were 25 male (62%) and 15 female (38%) patients with an age range of 10-37 years (average age, 20 years). The most frequent lesion locations were the diaphysis of the tibia (16 patients) or of the femur (15 patients). Radiographs showed a broad-based soft-tissue mass that was attached to the cortex (all patients) and showed cortical thickening (33 patients), cortical scalloping/erosion (37 patients), and/or perpendicular periosteal reaction (38 patients) extending into the soft-tissue mass. Soft-tissue masses were well defined in 91%-100% of cases and surrounded a median of 50%-55% of the cortex. Lesions commonly showed low attenuation at CT (10 patients) and high signal intensity on T2-weighted MR images (10 patients), reflecting the high water content of these largely chondroblastic lesions. Focal areas of adjacent marrow replacement were common at MR imaging (nine patients) but represented reactive changes unless they were in direct continuity with the overlying soft-tissue mass (this was rare, occurring in only one patient, and represented marrow invasion). Review of pathology reports revealed that all lesions contained chondroid tissue, which predominated in 34 patients., Conclusion: The radiologic appearance of periosteal osteosarcoma is a broad-based surface soft-tissue mass causing extrinsic erosion of thickened underlying diaphyseal cortex and perpendicular periosteal reaction extending into the soft-tissue component. Reactive marrow changes are commonly seen at MR imaging, but true marrow invasion is rare.

Purpose: To describe the characteristic features of liposclerosing myxofibrous tumor (LSMFT) of bone., Materials and Methods: The radiographs and clinical histories of 39 patients (21 male, 18 female; mean age, 42 years; age range, 15-69 years) with histologically verified LSMFT of bone were retrospectively studied., Results: LSMFT had a predilection for the proximal femur; more than 90% (30 of 33) of the femoral lesions were in the intertrochanteric region. Radiographs showed an indolent growth pattern with a well-defined and often extensively sclerotic margin. The bone contour either was normal or showed mild expansile remodeling. Mineralization within the lesion was not uncommon. Scintigrams showed mild to moderate focal tracer accumulation. Findings at computed tomography reflected those at radiography, whereas magnetic resonance imaging findings were nonspecific. Four (10%) patients had evidence of malignant transformation., Conclusion: The radiologic appearance of LSMFT in the intertrochanteric region of the femur is characteristic. The substantial prevalence of malignant transformation associated with LSMFT underscores the need for close observation of this lesion.

Purpose: To evaluate previously described radiologic prognostic factors in extremity osteosarcoma., Materials and Methods: In 47 pediatric patients, available images were evaluated for seven prognostic factors at diagnosis and seven additional factors after preoperative chemotherapy. These factors were correlated with histopathologic response and clinical outcome. The association of histopathologic response and outcome was also evaluated., Results: Metastases at presentation and a > 20-cm-diameter soft-tissue mass were predictive of a poor outcome but occurred in few patients. Factors most predictive of < 90% tumor necrosis after chemotherapy included an increase or no change in soft-tissue mass size and increased bone destruction. Although a significant relationship (P < .05) was found between histopathologic response and outcome, no factors predictive of histopathologic response were also predictive of outcome. The accuracy of pathologic response in predicting outcome was 66%., Conclusion: Radiologic studies are of only limited use in predicting which patients with extremity osteosarcoma will have a poor response to chemotherapy or a poor outcome, and are not useful in predicting a good response or outcome.

Four patients, ranging in age from 6 to 32 years, with surgically proved parosteal lesions of the femoral neck are presented. In one case, magnetic resonance (MR) imaging was the initial study ordered prior to plain radiography, and in three cases MR imaging was performed after plain radiography. Findings in the MR images were abnormal in all four cases; however, the nidus was not identified prospectively. Incorrect diagnoses based on findings at MR imaging of secondary marrow edema and/or synovitis included Ewing tumor, osteonecrosis, stress fracture, Lyme arthritis, and juvenile inflammatory arthritis. In all four cases, the correct diagnosis of intracapsular osteoid osteoma was made following (a) review of plain radiographs leading to a high index of suspicion and (b) performance of thin-section computed tomographic (CT) studies (in one case a screening CT study with 1-cm-thick sections failed to depict the lesion). In three cases, isotopic bone scans provided useful guidance for planning the CT examination.

Plain radiography and magnetic resonance (MR) imaging were used to assess the extent of transphyseal involvement in 15 consecutive patients with long bone osteosarcoma and nonfused epiphyses. The findings were correlated with those from surgical and microscopic pathologic examinations. There were no cases of false-positive findings with either MR imaging or plain radiography. Conventional radiography accurately helped predict transphyseal spread in only nine of 15 cases (60%). Spread to the epiphysis was present in 12 of the 15 cases (80%) and was accurately predicted with MR imaging in all 12 cases. This finding contradicts the common misconception that the physis acts as a "barrier" to tumor spread.

High-resolution P-31 MR spectra were obtained in four patients with bone tumors of their distal extremities. In one case the tumor, a Ewing sarcoma of the tibia, was investigated during clinical remission after radiation therapy and chemotherapy. The other three cases - one low-grade chondrosarcoma of the tibial head, one malignant fibrous histiocytoma of the tibia, and one chondroblastoma of the medial femoral condyle - showed clinically active tumor growth, with corresponding increased metabolism as demonstrated by bone scintigraphy. The spectra of the three active tumors indicated a comparably high adenosine triphosphate content, similar to previously published spectra from animal tumors or human tumors implanted into animals. There were also high resonances of inorganic phosphate and low resonances of phosphocreatine; there were definite peaks in the phosphodiester and phosphomonoester regions, indicating the existence of these metabolites in the tumors. Slight but definite changes in the metabolite content were observed in one tumor after chemotherapy. The spectra of the unaffected leg did not show any well-resolved P-31 signals, which is typical for healthy bone. These are the first P-31 MR spectra of human bone tumors measured in patients to our knowledge.

Magnetic resonance (MR) imaging was performed on 14 patients with histologically proved osteosarcoma (mean age, 14.4 years). There was excellent correlation of intramedullary tumor extent as determined with MR imaging and pathologic examination (r = 99%). This was facilitated by the presence of a chemical shift artifact at the tumor-marrow interface on the T1-weighted images. The correlation between CT and pathologic findings was not as good (r = 84%). In a single patient, however, a 10-cm length of sclerotic bone was incorrectly interpreted as being tumor. If this case is excluded, the correlation between CT and pathologic findings improves significantly (r = 96%). T2-weighted images were optimal in demonstrating soft-tissue bulk and breach of the epiphysis or cortex. Vascular involvement was also readily defined. The T2 value of the tumor soft-tissue component decreased in patients who were deemed to have responded well to therapy. Two patients with very high T2 values after chemotherapy developed wide-spread metastatic disease and died. Phosphorus-31 MR spectroscopy of five patients with osteosarcoma showed elevated levels of phosphomonoesters (PMEs), inorganic phosphate (Pi), and phosphodiesters (PDEs). PME and PDE peak areas decreased in three patients after chemotherapy, while Pi peak areas increased.

A scintigraphic pattern is described for bone scans with 99m-Tc-polyphosphate and 99m-Tc-diphosphonate in which abnormal tracer accumulation extends beyond the known limits of certain skeletal lesions. The associated pathologic entities include benign and malignant tumors, infection, and trauma. The pathogenesis of "extended patterns" has not been proved but probably relates to regional hyperemia induced by associated lesions. Increased blood flow results in more tracer delivery to otherwise normal bone in the "watershed" areas of hyperemia, producing these patterns.

With postprocessing, the authors produced a single hybrid image that combines the complementary information in conventional T1- and T2-weighted magnetic resonance (MR) images. A 1-T MR imager was used to produce T1- and T2-weighted images (repetition time, msec/echo time, msec: 500/30, 1,500/120) of patients with various primary bone tumors. Various weighted sums and differences of these images were then formed. Weighted subtraction allowed formation of hybrid images with high contrast between tumor and all adjacent normal tissues (muscle, fat, bone marrow), unlike the original T1- and T2-weighted images. Certain weighted sums of the acquired images simultaneously display the high signal-to-noise and clear anatomic detail of the T1-weighted technique along with the high contrast between extraosseous tumor and muscle of the T2-weighted image. A single hybrid MR image can contain useful characteristics both of T1- and T2-weighted images, making it easier for one to detect the extent of an abnormality.