Does higher field strength translate into better diagnostic accuracy? A prospective comparison of breast MRI at 3 and 1.5 Tesla. Issue 114 (May 2019) - Dietzel, Matthias
Highlights: We performed a prospective monocentric study to compare 1.5 T and 3 T breast MRI for diagnosis of breast cancer. The diagnostic accuracy of breast MRI was comparably high between protocols at both field strengths. Protocols optimized for the specific scanner hardware yield excellent image quality and high diagnostic performance. Abstract: Objective: We performed a prospective monocentric study to inter-individually compare the diagnostic accuracy of breast MRI at 1.5 T and 3 T. Methods: During a consecutive period of 12 months all 982 patients receiving breast MRI according to standard indications (problem solving, preoperative staging) were randomized to one 3 T or 1.5 T scanner both equipped with dedicated 16-channel breast coils. Protocols at 1.5 T and 3 T were optimized and in line with international recommendations. Due to restricted time slot availabilities, the randomization-key was defined as 1/10 (3 T/1.5 T). All examinations were read by two experts in breast MRI (>25 and 8 years of experience) who assigned a BI-RADS category per breast. Histopathological verification or long-term MRI follow-up (>24 months) served as standard of reference. Results were analyzed using cross tabulations, standard estimates of diagnostic accuracy, Chi-square test and Mann-Whitney U test (alpha = 5%). Results: 1961 breasts were included. 1746 (89%) were imaged at 1.5 T and 215 at 3 T (11%). The 1.5 T and 3 T study cohort did not show significant differences regarding patient age (P = 0.71), results of the reference standard (P = 0.09) and indication for MRI (P = 0.53). Overall Sensitivity (94.7%), Specificity (91.4%), Accuracy (91.9%) and Negative Predictive Value (99.0%) were within the range of the literature. Pairwise comparison of Sensitivity (1, 5 T/3 T: 94.1/97.9%), Specificity (91.6/%89.3%), Accuracy (92.0%/91.2%) and Negative Predictive Value (98.9%/99.3%) were without significant differences (P = 0.29-0.74). Conclusion: In this prospective monocentric study, we identified comparably high diagnostic accuracy for both 1.5 T and 3 T breast MRI. Both 1.5 T and 3 T are equally suited for breast imaging.