Mammoscintigraphy in evaluation of the patients with breast disorders

Full text: Breast cancer is the most common malignant tumour in women and its incidence is rising about 3% per year. Early detection of breast cancer decreases mortality and allows better treatment options. Although mammography has been used as the most effective method for early breast cancer detection it has some serious limitations. Approximately 25% of women have dense glandular breast tissue, which can obscure underlying tumours on mammography. This and some other factors are responsible for low specificity and positive predictive values (range 20-30%) of mammography. Therefore, only one out of every 4-6 mammographically suspicious lesions will prove to be malignant on biopsy. To improve these values several different methods, such as ultrasound (US), have emerged as complementary techniques in evaluation of breast lesions. Benign breast lesions could have similar sonographic appearance to malignant ones and therefore when indicated US-guided biopsy is performed. Most recently scintimammography with Tc-99m MIBI has emerged as a new non-invasive nuclear medicine technique. If a non-invasive imaging technique or combination of techniques can reduce the number of unnecessary biopsies it would be a great saving in cost as well as patient anxiety. The aim of this study was to determine the role of mammoscintigraphy (MS) in a multi modality diagnostic approach to the patients with breast disorders. One hundred thirty one patients (130 female and 1 male), aged from 27 to 79 years (mean 52.0) with different kind of breast disorders were included in this study. Mammoscintigraphy was performed 5 minutes after intravenous injection of 740 MBq of Tc-99m labeled MIBI. Anterior and lateral planar imaging followed by SPECT was acquired. Tumour to background (T/B) ratio was calculated on tomography and planar scans. X-ray mammography(MM), ultrasonography (US) of the breast and when it was indicated US-guided fine needle aspiration biopsy (US-FNAB) were performed. Among the 131 evaluated, 27 patients had malignant breast lesions. Ability to differentiate malignant breast lesions from benign breast disorders was calculated for evaluated diagnostic techniques in the terms of sensitivity (Sn), specificity (Sp), accuracy (Acc), positive predictive value (PPV) and negative predictive value (NPV). The diameters of evaluated malignant lesions were from 5 to 40 mm (median 15 mm). The smallest malignant lesion, detected on mammoscintigraphy was 5 mm in diameter. T/B ratio on planar mammoscintigraphy scans ranged from 1.11 to 2.34 (mean 1.63) whereas on SPECT scans it ranged from 1.47 to 5.39 (mean 2.74). The difference between calculated T/B ratio on planar and SPECT scans was highly significant (p<0.000001). In our opinion mammoscintigraphy is able to provide valuable information in evaluation of patients with breast disorders. In certain circumstances this functional diagnostic procedure should be added to the morphological procedures (mammography, ultrasonography) in an optimal multi modality diagnostic approach. In this way management of patients with malignant breast lesions as well as with benign breast disorders could be improved significantly. (author)