Diagnostic accuracy of Tc-99m-sestamibi breast imaging: Multicenter trial results

Although mammography is well established as a first-line tool for breast ca ncer screening and detection, efforts to develop complementary procedures c ontinue. Observation of Tc-99m-sestamibi tumor uptake provided the impetus for its evaluation as an adjunctive technique. This trial's objectives were to determine in a multicenter trial the diagnostic accuracy of 99mTc-sesta mibi in women with suspected breast cancer and to investigate factors influ encing diagnostic accuracy, Methods: Our multicenter trial enrolled 673 wom en (387 with nonpalpable abnormalities; 286 with palpable abnormalities) sc heduled for excisional biopsy or mastectomy. Blinded and unblinded interpre tations of scintigraphic images were compared with core laboratory establis hed histopathologic diagnoses to define the diagnostic accuracy of 99mTc-se stamibi breast imaging. Results: Blinded readers' diagnostic accuracy was 7 8%-81%. Inter-reader agreement was excellent, ranging from 95% to 100% (kap pa = 0.82-0.99). Overall institutional sensitivity and specificity for 99mT c-sestamibi breast imaging were 75.4% and 82.7%, respectively. In this popu lation with a 40.1% disease prevalence, the positive predictive value was 7 4.5% and the negative predictive value was 83.4%. The negative predictive v alue was 94% in patients with a 40% or lower mammographic likelihood of bre ast cancer. Sensitivity was higher for palpable abnormalities; specificity was higher for nonpalpable abnormalities. Sensitivity was decreased for tum ors <1 cm in largest dimension but appeared not to be affected by patient's age. Conclusion: As an adjunct to current procedures, 99mTc-sestamibi brea st imaging may contribute to patient management decisions in selected popul ations, including women with dense breasts, mammographically indeterminate lesions >1 cm, and palpable abnormalities.