Abbreviated MRI for Preoperative Assessment of Breast Cancer: is Maximal Intensity Projection (MIP) of the First Post Contrast Acquisition Subtracted (Fast) Sequence Sufficient for Disease Evaluation?

Objectives: The aim of this study was to assess the diagnostic performance of abbreviated MRI (AMRI) using the maximal intensity projection (MIP) reconstruction of the first post-contrast acquisition subtracted (FAST) compared with MIP+FAST and full-protocol MRI (fpMRI) for the preoperative assessment of breast cancer (BC) in a biopsy-proven cancer population.

Methods: In this monocentric retrospective study, two readers consensually assessed two AMRI protocols consisting of MIP reconstruction of the FAST (MIP) and MIP+FAST. 228 patients were included with a breast MRI performed between 2013 and 2014, 207 of them (90.8%) had biopsy-proven cancer with 256 lesions. Data of MIP and MIP+FAST were compared to full-protocol MRI (fpMRI) reading and to the reference standard including 6-month follow-up imaging and pathology as the reference.

Results: MIP, MIP+FAST and fpMRI demonstrated a per-lesion sensitivity for BC detection of 87.5% (224/256, 95%CI: 82.9-91.3%) and 97.7% (250/256, 95-99.1%) and 98.4% (252/256, 96.1-99.6%), respectively with a statistical difference between MIP compared to MIP+FAST and fpMRI when considering confidence intervals. Per-lesion specificity was not different [MIP: 47.6% (10/21, 25.7-70.2%), MIP+FAST: 52.4% (11/21,29.8-74.3%, fpMRI: 66.7% (14/21, 43-85.4%)].

Conclusion: AMRI using only MIP is not accurate for the pre-operative assessment of BC due to lower sensitivity when compared to MIP+FAST and fpMRI. AMRI using the MIP+FAST acquisition in the preoperative setting seems promising as it could be used as the same protocol for both screening and staging in case of positive cases, without need for a recall fpMRI. This needs confirmation with cohort including higher rate of negative cases in order to evaluate the specificity.