Increased pyrophosphate rib uptake: clinical correlation

Two hundred and thirty-one patients had 270 bone scans. Increased rib uptake was correlated with radiological findings. Interpretation of results whether due to benign or to metastatic disease depends on other observations. These include whether the uptake is localized or along the rib outline, single or multiple, and associated with other abnormal uptake in the rest of the skeleton. Abnormal rib uptake was encountered in 23% of patients scanned for malignant disease and 10% of patients scanned for benign conditions. In the first group 34% were true positive and of these, rib lesions were multiple in 32% and solitary in 2%. In 20% the rib uptake was due to benign conditions and in 46% it was indefinite because of absent radiological findings. In this last difficult group 17% were due to probably early rib metastases and 29% were due to benign causes. Rib metastases were missed in only two cases, 1.1%. One case was multiple myeloma and the other was direct extension from underlying anaplastic lung carcinoma.