B. K. Das, P. K. Pradhan1, S. Deswal
Department of Nuclear Medicine, Utkal Institute of Medical Sciences, Bhubaneswar, 1S. G. Postgraduate Institute of Medical Sciences, Lucknow, India
Background: Breast cancer has been found to be the first cause of cancer death among women in urban areas in India. Most patients come in stage II and above, many times delayed due to absence of a definitive diagnostic procedure. X-ray mammography and other imaging modalities lack in specificity in comparison to recently introduced scintimammography (SMG) which is performed using Sestamibi or Tetrofosmin. Efforts have been made to use MDP in place of Sestamibi, which is otherwise used for bone scanning and is significantly cheaper and has also the advantage of obtaining bone scan on the same day in one go. The purpose of this study is to compare the efficacy of both agents.
Materials and Methods: One hundred and twenty-three consecutive patients with confirmed diagnosis of breast cancer clinically and histopathologically were subjected to SMG using 20 mCi of Tc99m-MDP (BRIT, BARC, Mumbai, India) and a dual-headed gamma camera using standard technique. SMG was performed in another 105 consecutive similar patients using the same standard technique and equipment, but with Tc99m-Sestamibi (Sanlar). Thirty patients clinically suspected of having breast cancer and later confirmed were subjected to SMG using both agents on two separate days. Each scan was evaluated by two nuclear physicians. Ratio of tracer uptake in the lesion and normal tissue was calculated.
Results: Sensitivity and specificity were found to be 96.9% and 92.2%, respectively, in patients with Tc99m-MDP and 98.1% and 93.7%, respectively, in patients using Tc99m-Sestamibi. Out of 30 cases in whom SMG was performed using both agents, 28 (93%) showed concordant findings (both positive 16, both negative 12). In two patients, Sestamibi scans were positive but MDP scans were negative. In 16 MIBI-positive cases, 3 showed concentrations in axillary lymph nodes, which were not seen in MDP scan. In 16 MDP-positive cases, 4 showed metastatic involvement of the skeletal system. The activity ratios in MIBI and MDP scans were similar and varied from 1.3 to 5.7. In one case, a small lesion in the other breast was not visualized in MDP scan.
Conclusions: The sensitivity and specificity found in our studies is higher than in many multicentric studies, which may be due to the fact that most patients were in stage II and higher at the time of diagnosis. Tc99m-Sestamibi is potentially better than Tc99m-MDP in detection of malignant lesions. However, not only is MDP cheaper, but also the whole body bone scan which can be performed in one go can provide vital information regarding metastatic involvement of the skeletal system. Tc99m Sestamibi remains the choice radiopharmaceutical for early diagnosis of breast cancer. However, Tc99m-MDP can be recommended for diagnosis of breast cancer in cases suspected to be in stage II and higher with the additional benefit of getting vital information regarding involvement of skeletal system.