T1-WEIGHTED MAGNETIC-RESONANCE-IMAGING IN BREAST-CANCER VERTEBRAL METASTASES - CHANGES ON TREATMENT AND CORRELATION WITH RESPONSE TO THERAPY

Purpose: To document the MR appearances of vertebral metastases in bre ast cancer on treatment and to determine whether a single T1-weighted (T1-W) sequence of the spine could provide a quick and effective metho d of response assessment. Patients and Methods: One-hundred and nine s pinal magnetic resonance (MR) examinations in 41 metastatic breast can cer patients on treatment were reviewed. The changes in number, size a nd signal intensity of vertebral metastases during 68 intervals (mean length 6.9 months) mere documented. T1-W signal intensity (SI) before and after treatment was assigned to three patterns: (A) low homogeneou s SI; (B) low heterogeneous SI; and (C) high homogeneous SI. For each interval between MR examinations, an objective assessment of the overa ll response (disease regression, no change, disease progression) to tr eatment of metastases was made based on standard assessment criteria. Results: The number and size of treated vertebral metastases increased in 47% and 43% of cases and showed no change in 53% and 53% of cases, respectively. A reduction in size of lesions was seen in 3% of cases only and no reduction in the number of lesions was seen. T2-W signal i ntensity changes occurred in approximately one-third of cases document ed. The most commonly observed SI change in 25% of all intervals (17 o f 68) was from type A to type B, There was no correlation between SI c hange and response to therapy, T2-W MR response assessment, based on c hanges in size and number of vertebral metastases, accurately predicte d progression of disease in 79% of cases and stable disease in 75% of cases. It did not predict regression of disease. Conclusion: A T1-W MR spinal assessment is a simple and effective method of evaluation of t herapeutic response of lytic and sclerotic vertebral metastases in bre ast cancer being able to distinguish patients with progressive disease from those,vith a favourable response (no change or disease regressio n) to therapy, These findings have important clinical implications.