The role of nuclear techniques in the multimodality imaging of metastatic bone disease

1042 Learning Objectives: 1. Review the imaging manifestation of metastatic bone disease seen with the commonly encountered clinical imaging modalities. 2. Improve the ability of the nuclear medicine physician to identify metastatic bone disease on nuclear studies. Abstract Body: Metastatic bone disease is a commonly encountered clinical entity. The nuclear medicine physician may be presented with manifestations of metastatic disease during the evaluation of a bone scan or in the analysis of a PET/CT or SPECT/CT study. In order to interpret these studies it is helpful for the physician to be familiar with the manifestations of metastatic bone disease on correlative imaging consisting of plain radiographs, CT, and MRI. A metastatic lesion on bone scan usually manifests as a focus of increased tracer uptake but an aggressive tumor may manifest as a photopenic area. Tumors that frequently metastasize to bone are prostate, lung, breast, renal and thyroid cancers and those with a lower rate of metastatic bone disease are colon and head and neck cancer. Increased tracer uptake within 3 month of therapy may be due to healing (flare phenomenon) whereas an increase in uptake at 6 months after therapy is usually due to progression of disease. On PET scan a metastatic focus may be manifest as an increase in uptake which can be distinguished from nonmalignant causes by the CT correlate. Knowledge of the tumor type is helpful in evaluating PET scans since some tumors are more metabolically active than others. On the plain film the most reliable indication of malignancy is a wide zone of transition between the lesion and normal bone. CT findings of metastatic disease are evaluated on bone windows with the most characteristic finding being a permeative appearance in the bone in the proper clinical context. MRI is the best modality for determining the extent of disease. On MRI malignant lesions have irregular margins, encase neurovascular structures, and invade bone. The following cases illustrate the findings of metastatic bone disease that may be seen using these commonly encountered clinical imaging modalities. Research Support (if any): None