The value of thallium and three-phase bone scans in the evaluation of bone and soft tissue sarcomas

Abstract

Thirty-seven patients with newly diagnosed or treated sarcomas had 47 sets of sequential thallium scans (TS) followed by three-phase bone scan (TPBS) on the same day. The diagnosis in all patients was verified by biopsy (n = 40) or long-term follow-up studies (n = 7). The sensitivity, specificity, and accuracy of TS and TPBS in detecting sarcomatous lesions was calculated: TS sensitivity was 88%, specificity 69%, and accuracy 83%; blood flow (BF) and blood pool (BP) sensitivity was 91%, specificity 54%, and accuracy 81%; delayed bone scan (DB) sensitivity was 88%, specificity 38%, and accuracy 74%. In 17 studies the flow and blood pool parts of the TPBS and TS demonstrated the soft tissue component of sarcomas, which would have been missed if only the delayed bone scan had been performed. The TS lesion to normal tissue ratio alone was not very helpful in differentiating sarcomas from benign conditions because some benign lesions are highly cellular and vascular while some malignant lesions, such as chondrosarcoma, have poor vascularity and a less cellular chondroid matrix. However, when the thallium ratio was correlated with similar ratios calculated from the BP image, it was found that if the TS lesion to normal tissue ratio exceeded the BP lesion to normal tissue ratio (12 patients), the specificity for detecting sarcomatous lesions was 100%. Nevertheless, the reverse was not true. The positive predictive value of this observation was 100% and the negative predictive value was 37%.

Clinical usefulness of thallium-201 scintigraphy and magnetic resonance imaging in the diagnosis of chondromyxoid fibroma

“…However, chondrosarcoma showed a lower average counts/pixel of lesion to contralateral normal tissue than osteosarcoma in both early and late phases of thallium-201 scan [16][17][18]. In chondrosarcoma a high rate of false-negative thallium-201 scans (three out of fi ve in their series) was reported [16]. On the other hand, there have been no detailed reports on thallium-201 scintigraphy of CMF, although Nakazora et al reported that thallium-201 scintigraphy demonstrated a strong accumulation of retention index (RI) at the lesion of CMF without commenting on early and late phases [13].…”

“…In general, late thallium-201 uptake was considered to be more specifi c for the diagnosis of malignancy. However, chondrosarcoma showed a lower average counts/pixel of lesion to contralateral normal tissue than osteosarcoma in both early and late phases of thallium-201 scan [16][17][18]. In chondrosarcoma a high rate of false-negative thallium-201 scans (three out of fi ve in their series) was reported [16].…”

Diagnostic value of Thallium-201 scintigraphy in differentiating malignant bone tumors from benign bone lesions

“…We considered that no statistical significance of WR might be due to relatively small volume of bone lesion compared with surrounding soft tissue and the change of 201Tl uptake to the surrounding muscle had the bigger impact on WR in both benign and malignant bone lesions. According to the previous reports [2,4,7,11,[14][15][16][17][18][19][20][21], 201Tl uptake depends on cell viability and metabolic condition and a high metabolic rate with malignancy was the most important factor determining differences in 201Tl uptake between malignant tumors and benign lesions. Moreover, 201Tl uptake on early imaging is affected by tumor vascularity and cellularity.…”

“…Functional nuclear scans reflect the metabolic activity of tumors and may provide important information regarding the biologic behavior. 201Tl scintigraphy has been used in clinical oncology to estimate the presence and biologic activity of tumors including bone and soft tissue tumors, and the utility of 201Tl scintigraphy has been reported to differentiate malignant tumors from benign lesions in bone and soft tissue [2][3][4][5][6][7][8][9][10][11][12][13]. However, these previous studies were composed of a relatively small number of bone tumors and most of the studies used only visual analysis [2,3,5].…”

“…There has been growing interest in using 201Tl scintigraphy for management of bone and soft tissue tumors since the early 1990s [3]. Several studies have reported 201Tl scintigraphy to be an effective diagnostic tool to differentiate malignant from benign areas of interest [2][3][4][5][6][7][8][9][10]. However, there are little published data for 201Tl scintigraphy dealing with only bone lesions [3] and no report has statistically evaluated the diagnostic capacity of 201Tl scintigraphy in a large number of bone lesions.…”