Yuka Yamamoto MD, PhD, Presenter: Nothing to Disclose

Yoshihiro Nishiyama, Abstract Co-Author: Nothing to Disclose

Yoji Kawaguchi MD, Abstract Co-Author: Nothing to Disclose

Sadatoshi Yasuda, Abstract Co-Author: Nothing to Disclose

Katashi Satoh MD, Abstract Co-Author: Nothing to Disclose

Motoomi Ohkawa MD, Abstract Co-Author: Nothing to Disclose

There are several reports about the usefulness of FDG PET in bone and soft-tissue tumors. However, little information is available on the comparison of FDG PET and Thallium-201 (Tl) scintigraphy. The aim of this study was to compare the uptake of FDG and Tl in the diagnosis of bone and soft-tissue tumors.

Thirty-one patients with untreated bone and soft-tissue tumors, who had undergone both FDG PET and Tl scintigraphy were examined. FDG PET imaging was performed at 1 hour post FDG injection. The planar Tl images were acquired 10 mins (early) and 2 hrs (delayed) after injection of Tl. FDG PET and Tl scintigraphy results were evaluated by visual and semi-quantitative analysis. For semi-quantitative analysis, a region of interest (ROI) was defined over the tumor. The standardized uptake value (SUV) was determined on FDG PET imaging. On Tl imaging, ROI was placed over the tumor (T) and contralateral normal tissue (N), and T/N ratio was determined for both early and delayed images (T/N(E) ratio and T/N(D) ratio, respectively). The interpretation of FDG PET and Tl scintigraphy findings was compared with the histological findings.

Histological findings revealed 24 patients with malignant bone and soft-tissue tumors, whereas 7 patients had benign bone and soft-tissue tumors. Diagnostic sensitivity, specificity and accuracy were 96%, 0% and 74%, respectively for FDG PET and 100%, 71% and 94%, respectively, for Tl scintigraphy in both the early and delayed images. The mean value of SUV in malignant lesions (9.3±7.0) was higher than that in benign lesions (3.7±1.2), but this difference was not statistically significant. In contrast, the mean values of T/N(E) ratio (3.7±2.5) and T/N(D) ratio (2.0±0.8) in malignant lesions were significantly higher than those of T/N(E) ratio (1.5±0.8) and T/N(D) ratio (1.2±0.4) in benign lesions, respectively (p<0.003).

Although FDG PET can depict both malignant and benign bone and soft tissue tumors, Tl scintigraphy is superior to FDG PET for differential diagnosis of bone and soft-tissue tumors.

Tl scintigraphy is recommended in the evaluation of differential diagnosis of bone and soft-tissue tumors.

Yamamoto, Y, Nishiyama, Y, Kawaguchi, Y, Yasuda, S, Satoh, K, Ohkawa, M, Comparison of FDG PET and Thallium-201 Scintigraphy in Diagnosis of Bone and Soft-tissue Tumors.  Radiological Society of North America 2006 Scientific Assembly and Annual Meeting, November 26 - December 1, 2006 ,Chicago IL. http://archive.rsna.org/2006/4442295.html