The Art of Mammography With Respect to Positioning and Compression—A Swedish Perspective

Intra- and inter-rater reliability of compressed breast thickness, applied force, and pressure distribution in screening mammography

Background

Ensuring equivalent and reproducible breast compression between mammographic screening rounds is important for the diagnostic performance of mammography, yet the extent to which screening mammography positioning and compression is reproducible for the individual woman is unknown.

Purpose

To investigate the intra- and inter-rater reliability of breast compression in screening mammography.

Materials and Methods

Eleven breast-healthy women participated in the study. Two experienced radiographers independently positioned and compressed the breasts of each participant in two projections—right craniocaudal and left mediolateral oblique—and at two time points. The spatial pressure distribution on the compressed breast was measured using a pressure sensor matrix. Applied force, compressed breast thickness, force in field of view, contact area, mean pressure, and center of mass (anterio-posterior and mediolateral axes) were measured. The reliabilities of the measures between the time points for each radiographer (intra-rater reliability) and between the radiographers (inter-rater reliability) were analyzed using the intraclass correlation coefficient (ICC).

Results

Intra- and inter-rater reliabilities from both projections demonstrated good to excellent ICCs (≥0.82) for compressed breast thickness, contact area, and anterio-posterior center of mass. The other measures produced ICCs that varied from poor (≤0.42) to excellent (≥0.93) between time points and between radiographers.

Conclusion

Intra- and inter-rater reliability of breast compression was consistently high for compressed breast thickness, contact area, and anterio-posterior center of mass but low for mediolateral center of mass and applied force. Further research is needed to establish objective and clinically useful parameters for the standardization of breast compression.

Development and validation of a novel measure of adverse patient positioning in mammography

PURPOSE

The primary aim was to develop and validate a novel mammography positioning measure, specifically incorporating parameters which might relate to mammography pain. We then explored relationships between the new adverse positioning score and (1) pain; (2) patient and technique factors.

METHODS

A 15-item instrument incorporating positioning features with potential to relate to mammography pain was developed. Participants' mammograms (n = 310) were reviewed for presence of these features. Validity was investigated using the Rasch model. Scores produced by the resultant measure were investigated for associations with patients' pain scores and relevant patient and technique factors, using Pearson correlation, analysis of variance, and multiple linear regression.

RESULTS

Statistical indices within the Rasch measurement framework provided good evidence that the measure reflected a coherent construct of adverse positioning. Thus, the scores produced with the measurement instrument were valid for use in further statistical analysis. There is, however, scope for improvement of the measure's discriminatory properties. Adverse positioning scores were higher for greater breast volumes (r = 0.12, p=.0391) and body mass index (BMI) (r = 0.13, p=.0349), and varied by mammographer (F(11,298) 2.38, p = .0078). The relationships with BMI and mammographer persisted in regression modelling. No relationship was found between adverse positioning and pain.

CONCLUSIONS

Evidence from Rasch analysis suggests that this novel measure is valid for quantifying a coherent "adverse positioning" construct in mammography. Adverse positioning scores varied by mammographer and were related to higher patient BMI but not to mammography pain. The measure warrants expansion, further refinement, and testing in larger studies.

Consensus about image quality assessment criteria of breast implants mammography using Delphi method with radiographers and radiologists

Aims

To identify image quality criteria that can be applied to assess breast implant (BI) mammograms according to radiologists and radiographers’ perspectives and to explore the level of agreement about criteria priority.

Methods

A two-round Delphi method using a questionnaire was applied to identify the level of agreement between experts, asking them to rank each image criteria available for mammography according to 4 possible answers (1 = need to have, 2 = nice to have, 3 = not pertinent/appropriate, 4 = do not know). Criteria for craniocaudal (CC), mediolateral-oblique (MLO) and lateral (ML), with and without Eklund manoeuvre, were included. This process was repeated after removing the less relevant criteria.

Results

Between first and second rounds, different results were obtained regarding the criteria to assess CC and MLO images. Details for anatomic areas were considered the most relevant by radiographers during the first round, while general criteria were prioritised during the second round. Radiologists focused more on analysis of the spread of the breast tissue, if the breast was aligned with detector’s centre and level of contrast. The analysis of implant flow, the BI anterior edge and the maximum retropulsion of BI when Eklund manoeuvre is performed were the specific aspects of BI imaging considered as relevant for assessment.

Conclusions

The importance of each criterion used to assess BI mammograms was not the same between radiographers and radiologists, suggesting the two groups of experts are looking for different requirements from the image. Further education and training is necessary to align strategies for assessing BI mammograms, and some criteria need to be adapted to reduce subjectivity.