Bone metastases, unless lytic and accompanied by a soft tissue component, are non-measurable by Response Evaluation Criteria In Solid Tumors (RECIST) criteria. The objective evaluation of their response to non-surgical treatment is notoriously difficult and most clinicians rely primarily on the extent of symptomatic benefit to assess treatment response.
MRI has been recognised as the most sensitive imaging technique in the detection of bone metastases.1
Early publications suggested the use of T1-weighted sequences to evaluate response to treatment.2
However more recent publications have indicated that MRI scans may not be entirely reliable3
and multiple imaging modalities in combination are suggested.4
FDG PET-CT is a relatively new hybrid imaging modality in the armamentarium of clinical oncologists. Its role in the staging of various malignancies and response assessment in lymphoma is well established. However, there is a dearth of information on its routine use in metastatic bone disease. In bone-dominant breast cancer use of PET scans (without CT correlation) to evaluate response to non-surgical treatments has been reported.5,6
This case illustrates the importance of carefully correlating clinical benefit with imaging results. It also highlights the limitations of MRI in the evaluation of treatment response in spinal metastasis. Despite apparent worsening of bony disease on MRI, our patient continued to be asymptomatic and in remission for over 13 months.
Accurate assessment of treatment response is vital to provide effective treatment as well as to avoid unnecessary treatment escalation. In this case PET-CT provided an effective tool to monitor treatment response in metastatic bone disease. Prospective trials in this area may prove useful.
- Bone metastases, unless lytic and accompanied by a soft tissue component, are non-measurable by Response Evaluation Criteria In Solid Tumors (RECIST) criteria.
- MRI has been recognised as the most sensitive imaging technique in the detection of bone metastases, however to evaluate response to treatment it may not be reliable
- A dearth of information exists on routine use of fluorodeoxyglucose (18FDG) positron emission tomography with computed tomography (PET-CT) in metastatic bone disease
- 18FDG PET-CT may provide an effective tool to monitor treatment response in metastatic bone disease.
- It is important to carefully correlate imaging results with clinical benefit.