An established standard imaging modality for detecting bone metastases in patients with breast cancer is through the use of 99mTc-hydroxymethylene diphosphonate (99mTc-IIDP) bone scintigraphy. It is clearly documented that sensitivity is generally high while specificity is often lower because of tracer uptake in non-malignant processes. The aim of this study is to evaluate the diagnostic performance of whole body 2-deoxy-2-[18F]-D- glucose positron emission tomography (18 F-FDG PET) and bone scintigraphy in the detection of bone metastasis in patients with breast cancer.
METHODS: There were 232 consecutive patients who underwent FDG PET for breast cancer staging/restaging at our center during the study period. We included those who only had a bone scintigraphy within a month before or after the PET scan. The results of each image interpretation were compared retrospectively by an experienced nuclear medicine physician. Per-patient and per-lesion detection rates were collected. Bone metastasis slams was established on the basis of multimodality imaging and/or clinical follow-up for at least 6 months Weighted kappa was also calculated to determine agreement between the two modalities.
RESULTS: Forty-seven patients were included in the study with ages ranging from 28-86 years. For the patient-based data, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 90%, 92.6%, 90%, 92.6%, and 91.5%, respectively, for FDG PET, and 95%, 44.4%, 55.9%, 92.3% and 66%, respectively,for bone scintigraphy. For the lesion-based data, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 66.4%, 90%, 94.7%, 50%, and 72.8%, respectively, for FDG PET, and 74.5%, 27%, 752%, 26.3% and 62.6%, respectively, for bone scintigraphy Agreement between the two modalities was slight.
CONCLUSIONS: Overall, FDG PET shows to be as sensitive as bone scintigraphy in picking up bone metastases Furthermore, on both per patient and per lesion bases; PET was shown to be more confirmatory and more accurate with evidence of statistical significance. FDG PET and bone scintigraphy should play complementary roles in the detection of skeletal metastases.