Audit on Image Quality of Diagnostic Breast Ultrasound [QSI Ref: XR-503]

Audit of image quality of breast masses on diagnostic ultrasound.

Diagnostic ultrasound of the breast is a commonly performed procedure for evaluation of breast-related signs and/or symptoms. High quality ultrasound images are crucial for accurate characterization of breast masses, which could affect patient outcome. 
The American College of Radiology (ACR) Practice Parameter for the Performance of a Diagnostic Breast Ultrasound Examination was first established in 1994, with the latest version revised in 2021. It serves as an educational tool to assist practitioners in providing appropriate radiological care for patients [1].

Technical factors that influence breast lesion characterization include appropriate use of transducer, lesion viewed in 2 orthogonal projections, and lesion dimensions recorded in 3 orthogonal planes. Image of the lesion without calliper is important for documentation of its margin. Image of the lesion with colour or power Doppler is required to assess for any internal vascularity. Appropriate gain setting is essential as some lesions may be obscured if the gain setting is too high, while some cysts may appear solid. If the gain setting is too low, some hypoechoic solid lesions may appear anechoic and be mistaken for simple cysts. Appropriate field of view is also important as the margin of the mass may be misconceived as indistinct when the field of view is set to a shallow depth. When the field of view is set too deeply, small lesions may appear minified and hinder characterization. Appropriate focal zone selection is crucial as inappropriate focal zone could cause artifacts and misinterpretation of breast lesions [1,2]. 

Specific image annotation is essential for lesion localization, including laterality of the breast, clockface notation, distance from nipple, and orientation of transducer with respect to the breast [1].

Equipment: 

Diagnostic breast ultrasound should be performed with a high-resolution, real-time, linear-array, broad bandwidth transducer operating at a centre frequency of at least 12 MHz or higher [1]. 

Image quality for lesion characterization: 
1. Lesion viewed in 2 orthogonal projections [1] 
2. Lesion dimension recorded in 3 orthogonal planes [1] 
3. At least 1 image of the lesion had no calliper [1] 
4. At least 1 image of the lesion with colour or power Doppler [1] 
5. Appropriate gain setting 
• Subcutaneous fat lobules should appear medium grey [1,2] 
6. Appropriate field of view 
• The field of view should include breast tissue and the pectoralis muscle [1,2] 
7. Appropriate focal zone selection 
• Focal zone should be at the centre of the lesion [1,2] 

Image annotation: 

1. Laterality of the breast [1] 
2. Clockface notation [1] 
3. Distance from nipple 
• As centimetre from nipple (CM FN) [1] 
4. Orientation of transducer with respect to the breast [1]

Indicators: 

The percentage of ultrasound scans which adhere to each of the standards.

Data items to be collected:

1. Is the appropriate transducer used? 
2. Is the lesion viewed in 2 orthogonal projections? 
3. Is the lesion dimension recorded in 3 orthogonal planes? 
4. Is there at least 1 image of the lesion with no calliper? 
5. Is there at least 1 image of the lesion with colour or power Doppler? 
6. Is the gain setting appropriate? 
7. Is the field of view appropriate? 
8. Is the appropriate focal zone selected? 
9. Is the laterality of the breast, clockface notation, distance from nipple, and orientation of transducer with respect to the breast labelled?

Suggested number:

Ultrasound scans of the breast for patients of all ages should be collected and reviewed. All cases performed during the preceding three months are included.

1. Publicise the reference standards for breast ultrasound scanning technique and annotations through in-person departmental radiology meetings and dissemination of written material to radiologists and sonographers. 
2. Display poster with sample images in compliance with reference standards at ultrasound rooms to remind practitioners of technical factors. 
3. Present audit findings to radiologists and sonographers in departmental meeting. 
4. Conduct breast ultrasound workshop with demonstration sessions highlighting the importance of technical factors, examination and image acquisition routine, and expected image quality, and offer hands-on practice. 
5. Re-audit 6 to 12 months after intervention to assess for improvement in practice. Continue the audit spiral to ensure sustained compliance with the standards.

1. Radiology information system (RIS) to review administrative details and reports. 
2. Picture archiving computer system (PACS) to review saved ultrasound images. 
3. Statistical computer software, such as Microsoft Excel, for recording and analysing data.

1. American College of Radiology. ACR Practice Parameter for the Performance of a Diagnostic Breast Ultrasound Examination. 2021; Available at: https://www.acr.org/-/media/ACR/Files/Practice-Parameters/US-Breast.pdf. Accessed 9 September 2024. 

2. Mendelson EB, Böhm-Vélez M, Berg WA, et al. ACR BI-RADS® Ultrasound. In: ACR BI-RADS® Atlas, Breast Imaging Reporting and Data System. Reston, VA, American College of Radiology; 2013. 

3. Baker, J.A. and M.S. Soo, Breast US: assessment of technical quality and image interpretation. Radiology, 2002. 223(1): p. 229-238.

Dr. EH Chan

Co-authors:

Dr. T Wong, Dr. CM Chau, Dr. TKB Lai, Dr. KFJ Ma