The role of imaging in the staging and treatment planning of primary malignant bone tumors in children

Imaging of primary bone tumors: determination of tumor extent by non-contrast sequences

Magnetic resonance imaging (MRI) is the modality of choice for determining the extent of a primary bone tumor. This article will discuss the MRI techniques needed to accurately define the intramedullary extent of a bone sarcoma, emphasizing the need for non-contrast T1-weighted sequences and highlighting the role of chemical shift imaging.

Is bone scintigraphy necessary in the initial surgical staging of chondrosarcoma of bone?

OBJECTIVE

To assess the value of whole-body bone scintigraphy in the initial surgical staging of chondrosarcoma of bone.

METHODS

A retrospective review was conducted of the bone scintigraphy reports of a large series of patients with peripheral or central chondrosarcoma of bone treated in a specialist orthopaedic oncology unit over a 13-year period. Abnormal findings were correlated against other imaging, histological grade and the impact on surgical staging.

RESULTS

A total of 195 chondrosarcomas were identified in 188 patients. In 120 (63.8%) patients the reports of bone scintigraphy noted increased activity at the site of one or more chondrosarcomas. In one patient the tumour was outside the field-of-view of the scan, and in the remaining 67 (35.6%) cases, there was increased activity at the site of the chondrosarcoma and further abnormal activity in other areas of the skeleton. Causes of these additional areas of activity included degenerative joint disease, Paget's disease and in one case a previously undiagnosed melanoma metastasis. No cases of skeletal metastases from the chondrosarcoma were found in this series. Multifocal chondrosarcomas were identified in three cases. In two it was considered that all the tumours would have been adequately revealed on the initial MR imaging staging studies. In only the third multifocal case was an unsuspected, further presumed low-grade, central chondrosarcoma identified in the opposite asymptomatic femur. Although this case revealed an unexpected finding the impact on surgical staging was limited as it was decided to employ a watch-and-wait policy for this tumour.

CONCLUSION

There is little role for the routine use of whole-body bone scintigraphy in the initial surgical staging in patients with chondrosarcoma of bone irrespective of the histological grade.

Role of MRI in paediatric musculoskeletal conditions

The aim of this review is to discuss the indications and use of MR imaging (MRI) in the paediatric musculoskeletal system. After briefly reviewing basic technical considerations the MRI appearance of the most relevant congenital, inflammatory, infectious, ischemic, and posttraumatic skeletal conditions, as well as benign and malignant bone and soft tissue tumours that are typical for the paediatric age group will be presented.

Image-guided percutaneous biopsy of intramedullary lytic bone lesions: utility of aspirated blood clots

The diagnostic value of aspirating blood clots while performing percutaneous biopsy of intramedullary lytic bone lesions was assessed. This was a retrospective analysis of 400 patients with intramedullary lytic bone lesions who underwent image-guided needle biopsy. The nature of the specimens obtained was noted from the histopathology records. In 83 (20.8%) of the 400 patients, the specimen obtained was either blood clot only or essentially blood clot with only tiny fragments of bone or soft tissue. Lesional tissue was present on needle biopsy specimens in 65 (78.3%) of the 83 cases, while in 18 (21.7%) cases no lesional tissue was obtained. In 24 of the 83 cases, there was no surgical histological diagnosis available. In the 59 cases where surgical histological diagnosis was available for comparison, the diagnostic accuracy for needle biopsy was 73%. Percutaneous biopsy provided the diagnosis allowing appropriate further management in 62 cases, for an overall diagnostic yield of 75%. The results of our study show a sufficiently good diagnostic value in obtaining blood clots as to necessitate routine attempts at obtaining such material while performing percutaneous biopsy of intramedullary lytic bone lesions.