Second-look ultrasound: Only for biopsy or more?

Abstract

Magnetic resonance imaging (MRI) is a clinically important and increasingly utilized modality in breast imaging. As with any breast imaging modality, there is need for an accurate and well-tolerated biopsy method to establish or exclude malignancy for suspicious lesions detected at breast MRI. When breast MRI was first utilized widely in the clinical setting, the systems needed for direct MRIguided core biopsy was relatively limited. Instead, second-look ultrasound examination (and subsequent ultrasound-guided core biopsy) were performed. Second-look ultrasound is a targeted ultrasound examination of the breast, which may be performed after detection of a breast lesion that is not definitively benign at MRI [1,2]. Information regarding lesion type, morphology, size, and location are obtained from the MRI examination and translated into the ultrasound examination. Second-look ultrasound examination should be performed using high-quality ultrasound equipment and careful technique, taking into account patient (and therefore breast) positional differences during MRI (prone) versus ultrasound (supine or decubitus) examinations [3]. In recent years, sophisticated equipment and software have been developed and marketed for core biopsy using direct MRI guidance. These methods have been shown to be safe and reliable. Nevertheless, second-look ultrasound examination (and subsequent ultrasound-guided core biopsy) remain a clinically relevant approach, as ultrasound-guided biopsy offers some advantages over MRI-guided biopsy. In particular, biopsy guided by ultrasound can be visualized in real-time and is generally less costly, more readily available, and more comfortable for the patient. Additionally, ultrasound-guided biopsy can be performed at the same time as the second-look ultrasound examination, does not require intravenous contrast administration, and certain areas of the breast (e.g. posterior lesions near the chest wall, axillary lesions, lesions near the nipple) are more accessible to ultrasound-guided biopsy than MRI-guided biopsy. However, MRI-guided core biopsy may be indicated if it cannot be established with certainty that the MRI lesion and the finding identified at second-look ultrasound are indeed one and the same [4–6]. Not uncommonly in cases of benign histology, a followup MRI is indicated to evaluate whether or not the clip placed after biopsy at second-look ultrasound correlates with the initial MRI finding, in order to confirm that the finding identified and biopsied at second-look ultrasound is the same finding as the initial MRI finding.