The efficacy of 99mTc-MIBI scintimammography in the evaluation of breast lesions

www.nuclmed.gr To the Editor: With interest we read the paper by Özülker et al (2010) [1]. For more than 15 years, scintimammography has been tested against mammography, ultrasound and MRI of the breast. Scintimammography has repeatedly shown high specificity for breast lesions. Although sensitivity rates are also favorable, scintimammography is less useful in non-palpable tumors [2]. The above study [1] included 46 patients, 43 of whom underwent biopsy or surgery, the gold standard for final evaluation of a breast tumor. Two thirds of patients had palpable tumors. Also, judging from the age of the patients, two thirds of their patients may have been premenopausal, although the exact menopausal status is not provided. These premenopausal two thirds of patients are of particular interest, because breast density is crucial for mammography, but not for scintimammography. Breast density is a mandatory factor to be given in any diagnostic breast test. The above study [1] does not provide any information on breast density. However, based on the results of mammography it may be assumed that breast density was a factor in mammography readings. Scintimammography is favorable in premenopausal women, because the tumor-to-background ratio is independent of breast density. The limiting factor is lesion size, and only lesions of 10mm or more can be accurately imaged [2]. Therefore, consensus has been achieved to not use scintimammography in a routine evaluation. The above study [1] did not provide lesion size in the present study. Reviewing the literature, big tumors have been accurately imaged. Taking the favorable sensitivity rates, a rather large lesion size must be assumed. Our study group has previously published a study enrolling 101 consecutive patients [3], also comparing different tracers for best imaging. While the best tracer was found to be sestamibi, we found a high specificity and a rather low sensitivity for the primary evaluation of breast lesions. Because the technique applied by Özülker et al (2010) is similar to that used in our study, results of a routine first line setting may also be expected to be similar. Therefore, it is not a study to evaluate any equivocal mammogram. Rather, they tested whether scintimammography would “replace” mammography. Because scintimammography is well known from previous studies, any additional study may not alter the widely accepted routine work-up of our female patients, using the same large field of view technique (LFOV). As a consequence, LFOV scintimammography should rather be used in a tertiary setting in patients with BIRADS III or IV, after routine diagnostic tests including sonography and mammography. In such patients, any test forgoing the need for invasive testing will be welcome by many colleagues. The study by Özülker et al (2010) [1] is another report on a favorable specificity of scintimammography. Because lesion size is not provided, no conclusion can be drawn on sensitivity issues for other patients. The efficacy of 99mTc-MIBI scintimammography in the evaluation of breast lesions and axillary involvement