Synopsis

Keywords: Body: Breast

This talk focuses on describing standard breast MRI protocol including T2WI, T1WI, DWI, and dynamic contrast enhanced (DCE) images. Purpose of each sequence in a clinical setting will be explained. The talk also covers pitfalls and artifacts that are commonly encountered in the image acquisition and interpretation.

Main text

This talk focuses on describing standard breast MRI protocol, including T2-weighted image (WI), T1WI, Diffusion weighted image (DWI), and dynamic contrast-enhanced (DCE) images.
Breast MRI is mainly scanned by scanners at relatively high field strength (1.5T or 3T) to ensure a sufficient signal-to-noise ratio (SNR). It is essential to ensure that the patient is comfortable being in a prone position for the duration of the scan. After determining the scan location with a localizer scan, T2WI is usually obtained first. Starting with a non-contrast MRI is safer to identify any inappropriate setting, including scan location, incomplete fat suppression (in case of fat-suppressed T2WI), or artifacts. In general, lesions with high signal intensity are likely to be benign, except for mucinous carcinoma, while most of the malignant lesions appear intermediate signals on T2WI. In addition, the high intensity around the tumor, prepectoral area, and subcutaneous area are associated with malignancy and aggressive features.
T1WI with and without fat saturation helps to locate and characterize the lesion. The high signal intensity of the lesions suggests hematoma or fat content. T1WI without fat suppression also helps delineate the lesion. DWI, commonly added as a part of the non-contrast protocol, will be discussed in detail in another talk.
The Dynamic contrast-enhanced images with pre-, early, and delayed phases after contrast agent　administration are the key images. Proper image acquisition is essential. Ideally, DCE images with fat suppression are desirable so that sufficiently homogeneous fat suppression can be achieved most of the time. If the scanner often fails to achieve homogeneous fat suppression, the alternative options of DCE images without fat suppression combined with subtraction may be a better option. The drawback of subtraction images is vulnerability to motion artifacts. The timing of the early scan is adjusted to capture the peak enhancement of breast cancer within the first 2 min after the injection of the contrast medium. At the same time, appropriate protocol settings with an in-plane resolution of 1 mm or less are desirable to allow margin and other morphological assessment of the lesion. If possible, adding high-resolution post-contrast images helps visualize detailed structures for pre-surgical evaluation, including intraductal extension.
Common artifacts encountered in breast MRIs are motion artifacts, aliasing artifacts of the arms outside FOV, and flow artifacts from the heart extending to the axillary area. Lesions closer to the edge of the FOV may be poorly visualized. Metal artifacts may hinder the evaluation of post-surgical recurrence. Before the MRI, any biopsy history and marker insertion must be carefully checked to prevent a wrong diagnosis. These tips are helpful in appropriate breast MRI acquisition and interpretation.

Acknowledgements

No acknowledgement found.