Volumetric and area-based breast density measurement in the predicting risk of cancer at screening (PROCAS) study

Mammographic density, defined as the proportion of the breast area in a mammogram that contains fibroglandular tissue, is associated with risk of breast cancer. However, measures of mammographic density are subject to variation in the underlying imaging process and in the assessments of observers. Automatic volumetric measures of breast density remove much of this variability, but their association with risk is less well established. We present density measurements produced using area-based visual analogue scales (VAS) and by volumetric assessment software (QuantraTM, Hologic Inc.) in the PROCAS study. The distributions of VAS scores (n = 22 327) and volumetric quantities (n = 11 653) are given, as are their relationships for subjects with results by both (n = 11 096), but these are not directly comparable as one is area-based and the other volumetric. Inter-observer variability in visual area-based estimation is examined by a scatter plot matrix

Practitioner variation of applied breast compression force in mammography

Rationale:Mammography practitioners control the amount of compression force applied to the breast. There are no quantifiable recommendations for optimal compression force levels for practitioners to follow. Clients report variations in pain and discomfort when compression force is applied. Until now practitioner compression force variability has not been investigated; even though this might lead to variations in client pain and discomfort. The primary purpose of this thesis was to investigate whether practitioner compression force variability exists.Method:Three research papers investigated practitioner compression force variability: one used a cross sectional design; two used longitudinal designs, one was single centre and the other was multicentre. Three further research papers investigated important issues which might confound practitioner variability results: the first investigated compression paddle bend and distortion; the second investigated how breast thickness and compression force vary; the third evaluated practitioner ability to grade breast density, visually. The final research paper was a ‘within client’ investigation to determine how image quality varied with breast thickness and compression force. Key findings:The research firmly demonstrates that practitioner compression force variability exists. Multicentre analysis (4500 client visits) confirmed two out of three screening sites with significant practitioner variability, with the third screening site having a minimum dictate of compression force at 100N. As displayed by MLO/CC projections clients underwent a 55%/57% (site one), 66%/60% (site two) and 27%/26% (site three) change in compression force through their three screening visits. The research confirmed that the compression force received by a client was highly dependent upon the practitioner, and not the client. Within an individual clients screening pathway the research has demonstrated that clients could receive significantly different compression force levels over time. Conclusion and further research:For the first time practitioner compression force variability has been identified. Novel methods for reducing breast thickness need investigating; an example of a novel method is the use of pressure rather than force