Accurate characterization of 99mTc-MDP uptake in extraosseous neoplasm mimicking bone metastasis on whole-body bone scan: contribution of SPECT/CT.

Abstract

BACKGROUND:

99mTc-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.

METHODS:

Data 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.

RESULTS:

A 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.

CONCLUSIONS:

99mTc-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.

• Authors: Linqi Zhang, Qiao He, Tao Zhou, Bing Zhang, Wei Li, Hao Peng, Xi Zhong, Liwu Ma, Rusen Zhang
• Journal: BMC medical imaging (BMC Med Imaging) Vol. 19 Issue 1 Pg. 44 (05 30 2019) ISSN: 1471-2342 [Electronic] England
• PMID: 31146746 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Radiopharmaceuticals
• Technetium Tc 99m Medronate

Topics

• Adult
• Aged
• Bone Neoplasms (diagnostic imaging, metabolism, secondary)
• Breast (diagnostic imaging, pathology)
• Diagnosis, Differential
• Female
• Humans
• Liver (diagnostic imaging, pathology)
• Lung (diagnostic imaging, pathology)
• Male
• Middle Aged
• Neoplasm Metastasis (diagnostic imaging, pathology)
• Radiopharmaceuticals (administration & dosage, pharmacokinetics)
• Retrospective Studies
• Sensitivity and Specificity
• Single Photon Emission Computed Tomography Computed Tomography (methods)
• Technetium Tc 99m Medronate (administration & dosage, pharmacokinetics)
• Whole Body Imaging (methods)
• Whole-Body Counting