Abstract
Background99mTc-labelled methylene diphosphonate (99mTc-MDP) uptake can occasionally be identified in extraosseous neoplasms on whole-body scans (WBSs) and may be misinterpreted as bone metastasis. The purpose of our study was to investigate the frequency of 99mTc-MDP uptake in extraosseous neoplasms and to assess the additional value of SPECT/CT for the localization and characterization of this unusual uptake.MethodsData from 7308 patients (SPECT/CT was performed in 2147 patients) with known cancer who underwent WBSs for metastatic work-up between May 2015 and July 2018 were retrospectively reviewed. The locations, numbers, and intensities of extraosseous 99mTc-MDP uptake were evaluated by WBS, and the intratumoural calcification was evaluated by SPECT/CT. The diagnostic accuracy of SPECT/CT in locating 99mTc-MDP uptake in extraosseous neoplasms was compared to that of WBS.ResultsA total of 41 patients showed 99mTc-MDP uptake in extraosseous neoplasms. Of these patients, 23 patients had uncertain lesions by WBS, and further SPECT/CT was performed. The incidence of 99mTc-MDP uptake in extraosseous neoplasms was observed to be 0.6% by WBS and 1.1% (by) SPECT/CT. During imaging analysis, WBS had an accuracy of only 35% (14/40), whereas SPECT/CT correctly located and diagnosed all 40 lesion sites in the 23 patients. Twenty-three lesion sites (57.5%, 23/40) showed moderate or high intensity of extraosseous 99mTc-MDP uptake. Of the 23 patients, 17 patients (73.9%, 18/23) with 31 lesion sites (77.5%, 31/40) presented with intratumoural calcification.Conclusions99mTc-MDP uptake in extraosseous neoplasms can be observed as 0.6% on WBS and is usually localized to the breast, liver, and lung. Nuclear physicians should be familiar with such extraosseous uptake when interpreting WBSs. SPECT/CT offers better accuracy than WBS alone for locating the majority of lesions present with intratumoural calcification.
Highlights
Whole-body bone scans (WBSs) using 99mTc-labelled methylene diphosphonate (99mTc-MDP) is the most sensitive examination for the detection of bone metastasis in patients with known cancer [1, 2]
A few studies have suggested that 99mTc-MDP uptake can occasionally be identified in some extraosseous neoplasms by WBS, which may be misinterpreted as bone metastases or skeletal involvement
To distinguish this finding from bone metastasis is important for patients with known cancer; this is difficult if WBS is used alone because of limited anatomical resolution
Summary
Whole-body bone scans (WBSs) using 99mTc-labelled methylene diphosphonate (99mTc-MDP) is the most sensitive examination for the detection of bone metastasis in patients with known cancer [1, 2]. A few studies have suggested that 99mTc-MDP uptake can occasionally be identified in some extraosseous neoplasms (including primary tumour [3,4,5] and metastatic lesions [6,7,8]) by WBS, which may be misinterpreted as bone metastases or skeletal involvement To distinguish this finding from bone metastasis is important for patients with known cancer; this is difficult if WBS is used alone because of limited anatomical resolution. In the last few decades, various authors have reported the potential value of SPECT/CT in the localization and characterization of 99mTc-MDP uptake in extraosseous neoplasms, including breast cancer, gastrointestinal stromal tumour, Ewing sarcoma, pyelonephritis, sclerosing pneumocytoma, and other diseases [3,4,5,6,7,8, 12,13,14,15] These case reports and pictorial essays refer to a single case or to a limited number of patients. The aims of present study were first, to investigate the frequency of extraosseous uptake of 99mTc-MDP in soft-tissue neoplasms and to discuss the possible mechanism, and second, to assess the additional value of SPECT/CT in the localization and characterization of this unusual uptake compared to WBS alone
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
