Extra patient movement during mammographic imaging: an experimental study

Are mammography image acquisition factors, compression pressure and paddle tilt, associated with breast cancer detection in screening?

OBJECTIVES

To assess the associations between objectively measured mammographic compression pressure and paddle tilt and breast cancer (BC) detected at the same ("contemporaneous") screen, subsequent screens, or in-between screens (interval cancers).

METHODS

Automated pressure and paddle tilt estimates were derived for 80,495 mammographic examinations in a UK population-based screening programme. Adjusted logistic regression models were fitted to estimate the associations of compression parameters with BC detected at contemporaneous screen (777 cases).Nested case-control designs were used to estimate associations of pressure and tilt with: (a) interval cancer (148 cases/625 age-matched controls) and (b) subsequent screen-detected cancer (344/1436), via conditional logistic regression.

RESULTS

Compression pressure was negatively associated with odds of BC at contemporaneous screen (odds ratio (OR) for top versus bottom third of the pressure distribution: 0.74; 95% CI 0.60, 0.92; P-for-linear-trend (Pt) = 0.007). There was weak evidence that moderate pressure at screening was associated with lower odds of interval cancer (OR for middle versus bottom third: 0.63; 95% CI 0.38, 1.05; p = 0.079), but no association was found between pressure and the odds of BC at subsequent screen. There was no evidence that paddle tilt was associated with the odds of contemporaneous, subsequent screen or interval cancer detection.

CONCLUSIONS

Findings are consistent with compression pressure, but not paddle tilt, affecting the performance of mammographic screening by interfering with its ability to detect cancers.

ADVANCES IN KNOWLEDGE

Inadequate or excessive compression pressure at screening may contribute to a reduced ability to detect cancers, resulting in a greater number of interval cancer cases.

Experience of pain during mammographic screening by three different compression paddles

INTRODUCTION

Experience of pain during screening mammography is shown to affect further attendance negatively. We aimed to explore the experience of pain during screening mammography using three different breast compression paddles.

METHODS

Using a self-report questionnaire, we collected information on pain experienced during mammography from 938 women screened in Bodø at Nordland Hospital County in 2018, as a part of BreastScreen Norway. Pain was assessed by a numeric rating scale (NRS, 0-10). A fixed paddle, a flexible paddle or a fixed paddle standardizing pressure (study paddle) were used during screening. Compression force (kg) was recorded by the radiographers for each screening examination. Log-binomial regression was used to determine the relative risk (RR) of severe (≥7 on NRS) versus mild/moderate (<7 on NRS) experience of pain associated with type of compression paddle, adjusting for breast tenderness, shoulder(s) and/or neck pain prior to screening, compression force, age, body mass index and screening history.

RESULTS

Mean score of self-reported experienced pain was 2.8 for the fixed, 2.3 for the flexible and 2.8 for the study paddle (p < 0.03 for fixed versus flexible and for flexible versus study paddle). Adjusted RR of severe pain was higher for the fixed (RRAdj 2.01, 95%CI 1.13-3.59) and the study paddle (RRAdj 2.52, 95%CI 1.44-4.42) compared to the flexible paddle. Breast tenderness was associated with a higher risk (RRAdj 1.93, 95%CI 1.04-3.58) of severe pain compared to no breast tenderness.

CONCLUSION

Women screened with the flexible paddle reported lower experience of pain than those screened with the fixed or study paddle.

IMPLICATION FOR PRACTICE

The flexible compression paddle might be the best choice regarding experience of pain in screening mammography. Breast tenderness should be considered by the radiographers in a practical screening setting.

Interprofessional research teams in radiography - where the magic happens

Based on publications and professional experiences, this article, intended for academic and clinical therapy/diagnostic radiographers, considers conducting research in interprofessional teams, including its values and how to go about achieving it. Whilst there is a growing number of journal papers published by interprofessional teams, almost nothing is published about how best to build interprofessional research relationships or harness the potential of the different professional experience to deliver novel research within the radiography literature. Thus, this article draws heavily on our experiences of creating, working within and leading interprofessional teams which have a specific focus on conducting radiography-related research. Suggestions are proposed about how to create an interprofessional research team and how to get the best out of it. Values of working within an interprofessional research team, to self, to research quality and to the end users of the research are considered.

Translating research evidence into clinical practice within a single breast imaging unit - A personal reflection

Health care organisations are required to deliver high quality evidence based and cost effective clinical care. Generating research evidence, appraising new published evidence and integrating it into clinical practice is time-consuming but an essential component in the continuous improvement of care delivery. This article is a personal reflection on the impact of research in clinical practice in a busy, single breast imaging unit from a number of different perspectives. It also highlights a number of benefits that are to be realised both from a service delivery perspective and across the whole staff team from engagement in such activity, which is an integral aspect of our work.

Blurred digital mammography images: an analysis of technical recall and observer detection performance

OBJECTIVE

Blurred images in full-field digital mammography are a problem in the UK Breast Screening Programme. Technical recalls may be due to blurring not being seen on lower resolution monitors used for review. This study assesses the visual detection of blurring on a 2.3-MP monitor and a 5-MP report grade monitor and proposes an observer standard for the visual detection of blurring on a 5-MP reporting grade monitor.

METHODS

28 observers assessed 120 images for blurring; 20 images had no blurring present, whereas 100 images had blurring imposed through mathematical simulation at 0.2, 0.4, 0.6, 0.8 and 1.0 mm levels of motion. Technical recall rate for both monitors and angular size at each level of motion were calculated. χ2 tests were used to test whether significant differences in blurring detection existed between 2.3- and 5-MP monitors.

RESULTS

The technical recall rate for 2.3- and 5-MP monitors are 20.3% and 9.1%, respectively. The angular size for 0.2- to 1-mm motion varied from 55 to 275 arc s. The minimum amount of motion for visual detection of blurring in this study is 0.4 mm. For 0.2-mm simulated motion, there was no significant difference [χ2 (1, N = 1095) = 1.61, p = 0.20] in blurring detection between the 2.3- and 5-MP monitors.

CONCLUSION

According to this study, monitors ≤2.3 MP are not suitable for technical review of full-field digital mammography images for the detection of blur. Advances in knowledge: This research proposes the first observer standard for the visual detection of blurring.

Analysis of motion during the breast clamping phase of mammography

OBJECTIVE

To measure paddle motion during the clamping phase of a breast phantom for a range of machine/paddle combinations.

METHODS

A deformable breast phantom was used to simulate a female breast. 12 mammography machines from three manufacturers with 22 flexible and 20 fixed paddles were evaluated. Vertical motion at the paddle was measured using two calibrated linear potentiometers. For each paddle, the motion in millimetres was recorded every 0.5 s for 40 s, while the phantom was compressed with 80 N. Independent t-tests were used to determine differences in paddle motion between flexible and fixed, small and large, GE Senographe Essential (General Electric Medical Systems, Milwaukee, WI) and Hologic Selenia Dimensions paddles (Hologic, Bedford, MA). Paddle tilt in the medial-lateral plane for each machine/paddle combination was calculated.

RESULTS

All machine/paddle combinations demonstrate highest levels of motion during the first 10 s of the clamping phase. The least motion is 0.17 ± 0.05 mm/10 s (n = 20) and the most motion is 0.51 ± 0.15 mm/10 s (n = 80). There is a statistical difference in paddle motion between fixed and flexible (p < 0.001), GE Senographe Essential and Hologic Selenia Dimensions paddles (p < 0.001). Paddle tilt in the medial-lateral plane is independent of time and varied from 0.04 ° to 0.69 °.

CONCLUSION

All machine/paddle combinations exhibited motion and tilting, and the extent varied with machine and paddle sizes and types.

ADVANCES IN KNOWLEDGE

This research suggests that image blurring will likely be clinically insignificant 4 s or more after the clamping phase commences.

What is the minimum amount of simulated breast movement required for visual detection of blurring? An exploratory investigation

OBJECTIVE

Image blurring in mammography can cause significant image degradation and interpretational problems. A potential source is due to paddle movement during image formation. Paddle movement has been shown to be as much as 1.5 mm. No study has yet been performed to determine how much motion would be noticeable visually. The aim of this study is to determine the minimum amount of simulated breast movement at which blurring can be detected visually.

METHODS

25 artefact-free mammogram images were selected. Mathematical simulation software was created to mimic the effect of blurring produced by breast movement during exposure. Motion simulation was imposed to 15 levels, from 0.1 to 1.5 mm stepping through 0.1 mm increments. 15 degraded images and 1 without blurring were de-identified, randomized and assessed on a blinded basis by two clinical experts to determine the presence or absence of blurring. Statistical testing was carried out to determine the consistency between the two observers.

RESULTS

The probability of simulated blurred image detection is the highest for the gaussian method and the lowest for soft-edged mask estimation.

CONCLUSION

The amount of simulated breast movement at which blurring can be detected visually for gaussian blur, hard-edge mask estimation and soft-edge mask estimation is 0.4, 0.8 and 0.7 mm, respectively. Cohen's kappa for all the levels of simulated blurring is 0.689 (p < 0.05).

ADVANCES IN KNOWLEDGE

This research establishes the concept of using probability to represent visual detection of blurring rather than defining a hard cut-off level.