Breast ultrasound knobology and the knobology of twinkling for marker detection.

Breast ultrasound utilizes various scanning techniques to acquire optimal images for diagnostic evaluation. During interventional procedures, such as ultrasound-guided biopsies or preoperative localizations, knowledgeable and purposeful scanning adjustments are critical for successfully identifying the targeted mass or biopsy marker or clip. While most ultrasound scanning parameters are similar across different vendors, detailed descriptions specifically addressing the scanning parameters-often referred to as "knobology"- for breast ultrasound is at best limited in the literature. This review highlights ten key operator-controlled adjustments (including transducer selection, beam focusing, power, depth, gain and time gain compensation, harmonic imaging, spatial compounding, dynamic range, beam steering, and color Doppler) that significantly influence image quality in breast ultrasound. Each adjustment is accompanied by an "In practice" section providing examples and practical tips on implementation. The last topic discusses color Doppler which is generally used in breast ultrasound for evaluating the vascularity of a finding. Color Doppler, or more specifically, color Doppler twinkling, can be leveraged as a technique to detect certain breast biopsy markers that are challenging to detect by conventional B-mode ultrasound. While the cause of color Doppler twinkling is still under active investigation, twinkling is a clinically well-known, compelling ultrasound feature typically described with kidney stones. A step-by-step guide on how to use color Doppler twinkling to detect these markers is provided.