Non-neoplastic variants of the sternum: SPECT/CT findings

Objectives To identify the non-neoplastic variants of the sternal uptake in patients known to have a primary tumor, referred for detection of metastases elsewhere

Methods Retrospective analysis of 50 eligible patients (17 males & 33 females) known to have a primary tumor underwent ^99mTc-MDP-bone scan for detection of metastases. All patients underwent SPECT/CT of the chest region. For each patient, ten subsites were evaluated (right & left sternocalvicular joints, right and left 1^st costo-sternal articulation, manubrium sterni, manubrio-sternal junction, body of the sternum, xiph-sternal junction, xiphoid process and other sub-sites (e.g. chondro-sternal articulations). The uptake was described as normal or abnormal. CT findings were categorized as normal/abnormal (arthritis, degenerative, developmental & congenital). Any patient with suspicious metastatic sternal lesion based on CT findings or abnormal tracer uptake was excluded.

Results A total of 500 sub-sites were analyzed. Increased uptake was seen in 189 sub-sites, 133 showed abnormal CT findings (95 arthritis, 33 degenerative, 3 developmental & 2 congenital) and 56 were unremarkable. Of the 311 with normal uptake, only 18 showed abnormal CT findings (8 arthritis & 10 degenerative). The association was statistically highly significant (P < 0.001).

Conclusions Increased sternal uptake is significantly associated with CT structural abnormalities and knowledge of these non-neoplastic variants is essential for correct interpretation of bone scans especially in patients with known cancers.