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 (99m)Tc sestamibi has been shown to be a valuable technique for the detection of breast cancer. Alternative radiotracers such as (99m)Tc maraciclatide may offer improved uptake in breast lesions. The purpose of this study was to compare relative performance of (99m)Tc sestamibi and (99m)Tc 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 (99m)Tc sestamibi and one with (99m)Tc 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 (99m)Tc sestamibi MBI and 19 of 21 (90%) were seen on (99m)Tc maraciclatide MBI (p = 1). Tumor extent measured with both radiopharmaceuticals correlated strongly with pathologic size ((99m)Tc sestamibi, r = 0.84; (99m)Tc 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 (99m)Tc sestamibi and 1.62 ± 0.37 (mean ± S.D.) for (99m)Tc maraciclatide (p = 0.53). No correlation was found between the L/B ratio and molecular subtype for (99m)Tc sestamibi (r s  = 0.12, p = 0.63) or (99m)Tc maraciclatide (r s  = -0.12, p = 0.64). Of 20 benign lesions, 10 (50%) were seen on (99m)Tc sestamibi and 9 of 20 (45%) were seen on (99m)Tc maraciclatide images (p = 0.1). The average L/B ratio for benign lesions was 1.34 ±0.40 (mean ±S.D.) for (99m)Tc sestamibi and 1.41 ±0.52 (mean ±S.D.) for (99m)Tc maraciclatide (p = 0.75). Overall diagnostic performance was similar for both radiopharmaceuticals. AUC from ROC analysis was 0.83 for (99m)Tc sestamibi and 0.87 for (99m)Tc maraciclatide (p = 0.64).

CONCLUSIONS: (99m)Tc maraciclatide offered comparable lesion uptake to (99m)Tc sestamibi, in both malignant and benign lesions. There was good correlation between lesion extent and uptake measured from both radiopharmaceuticals. (99m)Tc maraciclatide offered a marginal (but not significant) improvement in sensitivity over (99m)Tc sestamibi. Our findings did not support an association between the uptake of either radiopharmaceutical and tumor molecular subtype.

TRIAL REGISTRATION: ClinicalTrials.gov, NCT00888589.