Comparison of Tc-99m maraciclatide and Tc-99m sestamibi molecular breast imaging in patients with suspected breast cancer

Background: Molecular breast imaging (MBI) performed with Tc-99m sestamibi has been shown to be a valuable technique for the detection of breast cancer. Alternative radiotracers such as Tc-99m maraciclatide may offer improved uptake in breast lesions. The purpose of this study was to compare relative performance of Tc-99m sestamibi and Tc-99m maraciclatide in patients with suspected breast cancer, using a high-resolution dedicated gamma camera for MBI. Women with breast lesions suspicious for malignancy were recruited to undergo two MBI examinations-one with Tc-99m sestamibi and one with Tc-99m maraciclatide. A radiologist interpreted MBI studies in a randomized, blinded fashion to assign an assessment score (1-5) and measured lesion size. Lesion-to-background (L/B) ratio was measured with region-of-interest analysis. Results: Among 39 analyzable patients, 21 malignant tumors were identified in 21 patients. Eighteen of 21 tumors (86%) were seen on Tc-99m sestamibi MBI and 19 of 21 (90%) were seen on Tc-99m maraciclatide MBI (p = 1). Tumor extent measured with both radiopharmaceuticals correlated strongly with pathologic size (Tc-99m sestamibi, r = 0.84; Tc-99m maraciclatide, r = 0.81). The L/B ratio in detected breast cancers was similar for the two radiopharmaceuticals: 1. 55 +/- 0.36 (mean +/- S.D.) for Tc-99m sestamibi and 1.62 +/- 0.37 (mean +/- S.D.) for Tc-99m maraciclatide (p = 0.53). No correlation was found between the L/B ratio and molecular subtype for Tc-99m sestamibi (r(s) = 0.12, p = 0.63) or Tc-99m maraciclatide (r(s) = -0.12, p = 0.64). Of 20 benign lesions, 10 (50%) were seen on Tc-99m sestamibi and 9 of 20 (45%) were seen on Tc-99m maraciclatide images (p = 0.1). The average L/B ratio for benign lesions was 1.34 +/- 0.40 (mean +/- S.D.) for Tc-99m sestamibi and 1.41 +/- 0.52 (mean +/- S.D.) for Tc-99m maraciclatide (p = 0.75). Overall diagnostic performance was similar for both radiopharmaceuticals. AUC from ROC analysis was 0.83 for Tc-99m sestamibi and 0.87 for Tc-99m maraciclatide (p = 0.64). Conclusions: 99mTc maraciclatide offered comparable lesion uptake to Tc-99m sestamibi, in both malignant and benign lesions. There was good correlation between lesion extent and uptake measured from both radiopharmaceuticals. Tc-99m maraciclatide offered a marginal (but not significant) improvement in sensitivity over Tc-99m sestamibi. Our findings did not support an association between the uptake of either radiopharmaceutical and tumor molecular subtype.