Clinical utility of bone and gallium scintigraphy for assessing soft tissue neoplasms in the extremities

A prospective study of 6.2 patients evaluated the usefulness of bone and gallium scintigraphy prior to definitive surgery for soft tissue masses in the extremities. Bone scans in 62 patients included blood pool images in 40. Ga-67 imaging was done in 61. Surgery disclosed 30 soft tissue sarcomas, 25 benign tumors, and 7 negative reexplorations of excisional biopsy sites. For sarcomas, 21/21 blood pool and 20/30 delayed bone images showed abnormal tracer activity in the soft tissue mass. Bone adjacent to sarcomas showed abnormal uptake in 11 cases. In 7 of 11, x-rays showed cortical erosions verified by surgery. In 4 of 11, x-rays were normal, but, on section, neoplasm extended to the periosteum. Ga-67 scans were abnormal in 26/29 patients with sarcomas. Three malignancies were Ga-67 negative (one malignant fibrous histiocytoma and two small synovial sarcomas). In 5 cases metastases were detected by Ga-67, 3 were unsuspected non-pulmonary metastases. For benign tumors, 5/19 blood pool images and 5/25 delayed images showed abnormal soft tissue tracer activity. Ga-67 localized in 4/5 acute inflammatory lesions but only in 1/20 non-inflammatory masses. Combined bone and Ga-67 scintigraphy have a high predictive value for presence or absence of soft tissue malignancy. A negativemore » blood pool image strongly indicates a benign lesion and may obviate Ga-67 imaging. Bone imaging reveals periosteal involvement not detected by routine x-rays. Ga-67 scintigraphy is useful for detecting occult non-pulmonary metastases.« less