What causes lower neck uptake in bone scans?

Lower neck uptake, frequently seen on anterior views of bone scans done with 99mTc-phosphate compounds, was studied in 122 patients to determine its incidence and etiology. Increased uptake was identified in the lower neck anteriorly in 46 patients (38%). In 14 of these, moderately severe to severe arthritis appeared to cause the uptake; metastatic disease was the cause in 8 cases; and in 1 case there was prominent uptake in the thyroid cartilage. Positioning artifact accounted for the uptake in the other 23 cases. Thyroid uptake was never observed.