A review of mammographic positioning image quality criteria for the craniocaudal projection

Abstract

Detection of breast cancer is reliant on optimal breast positioning and the production of quality images. Two projections, the mediolateral oblique and craniocaudal (CC), are routinely performed. Determination of successful positioning and inclusion of all breast tissue is achieved through meeting stated image quality criteria. For the CC view, current image quality criteria are inconsistent. Absence of reliable anatomical markers, other than the nipple, further contribute to difficulties in assessing the quality of CC views. The aim of this paper was to explore published international quality standards to identify and find the origin of any CC positioning criteria which might provide for quantitative assessment. The pectoralis major (pectoral) muscle was identified as a key posterior anatomical structure to establish optimum breast tissue inclusion on mammographic projections. It forms the first two of the three main CC metrics that are frequently reported (1) visualization of the pectoral muscle, (2) measurement of the posterior nipple line and (3) depiction of retroglandular fat. This literature review explores the origin of the three metrics, and discusses three key publications, spanning 1992 to 1994, on which subsequent image quality standards have been based. The evidence base to support published CC metrics is sometimes not specified and more often, the same set of publications are cited, most often without critical evaluation. To conclude, there remains uncertainty if the metrics explored for the CC view support objective evaluation and reproducibility to confirm optimal breast positioning and quality images.

Full‐field digital mammography: the ‘30% rule’ and influences on visualisation of the pectoralis major muscle on the craniocaudal view of the breast

“…As some traditional positioning techniques use a one‐handed approach to pull the breast onto the IR, and with positioning often executed from the lateral side of the breast, these improvements to positioning techniques may indeed prove to be valuable in increasing PMM visualisation. On the other hand, if in the previously published studies 9–17 52–89% of images are reported to not visualise the PMM, it becomes a questionable aim. A ‘rule’ that does not apply to 52–89% of images should not be viewed as a criterion, let alone a ‘rule’ for quality assurance.…”

“…Bassett’s ‘30% rule’ does not explicitly state a unilateral, bilateral or overall visualisation rate. A clear definition is also not provided by the subsequent literature, 9–17 accreditation standards 3–5,18–20 or key educational texts. This conflicts with clinical approaches to image quality review and radiological interpretation which typically compare paired left and right (bilateral) images.…”

“…This conflicts with clinical approaches to image quality review and radiological interpretation which typically compare paired left and right (bilateral) images. A wide range of percentages (11–48%) for the visualisation of the PMM has been cited in the literature, without benchmarking to any specific percentage, apart from the 32% reported by Basset et al in 1993 9–17 (Table 1). Internationally, there is a wide discrepancy between accrediting bodies regarding both the need to visualise the PMM on the CC view and its achievability, which raises the question of its value as an image quality criterion (Table 1).…”

Interobserver variability in quality assessment of magnetic resonance images

“…Specifically, studies regarding quality in the diagnostic imaging proposed to date are directed towards the analysis of the influence of the image quality distortions on the perception of images [ 43 ]. Also, Sweeney et al [ 39 ] and Rafferty et al [ 33 ] presented findings on the influence of image quality on the perception of the pathology. In that work, images were artificially distorted using blur or noise.…”

“…In that work, noisy images were used to determine the agreement among radiologists on the diagnosis of angina pectoris due to coronary heart disease for stenosis severity. Sweeney et al [ 39 ], reviews mammographic positioning image quality criteria being the results of years of discussion on the influence of image quality on the detection of breast cancer. Such criteria have been established taking into account observer variability.…”