World health organisations have questioned whether the value of mammography in breast screening programmes is diminishing, as well as discussing how screening programmes could be improved (Autier et al, 2018). Diagnostic imaging modalities are continually, and rapidly, developing which has led some studies to conclude that in terms of sensitivity, magnetic resonance imaging (MRI) is now clearly superior and preferable for use in breast screening.
This is supported by the triple modality screening study by Riedl et al (2015). Triple modality screening involves the use of MRI, ultrasound and mammography. The research showed that regardless of patient age, breast density or risk status, MRI has a much higher sensitivity of 90%, compared with 37.5% for both mammography and ultrasound. The study used a sample size of 559 with 1,365 screening rounds. A more recent study undertaken by Lee-Felker et al (2017) produced almost identical results for sensitivity, using the same equipment as Riedl et al (Siemens 1.5T Magnetom Avanto), albeit with a much smaller sample size of 52. This supports the reliability of the results.
Whilst the importance of high sensitivity in avoiding false negatives is clear, there are drawbacks with the use of MRI alone. Both Riedl et al and Lee-Felker et al draw attention to the fact that MRI has a lower specificity and PPV compared with both mammography and ultrasound. The production of higher false positive rates is concerning because unnecessary treatment of breast cancer carries risk and considerable distress for the patient. This reinforces the necessity of an optimal balance between thresholds.
Lee-Felker et al’s study showed that the use of contrast-enhanced spectral mammography had a similar sensitivity to MRI and a much higher PPV, and therefore is potentially suitable as a substitute for MRI. This questions the relevance of the previous study since during the time period between the research trial and the publishing of findings, mammographic technology has progressed, as shown in the ‘TOMMY’ trial (2015), with potential to reduce the numbers of false-positive recalls. In this way, mammography could be a more efficient, cost-effective modality by avoiding unnecessary treatment.
A study of false-negative MRI breast screening conducted in Manchester by Maxwell et al (2016) concluded that mammography remains “important” for high-risk women. The use of only a small population of twenty-three women raises questions about how representative of wider populations, and therefore its relevance. However, it raises an interesting point by warning against the use of dynamic scans to differentiate between malignancy and benignity. According to the article, it is not always accurate since a smaller cancer may not demonstrate typical rapid uptake and washout. However, it would be necessary to look at other research to produce a conclusion. Because no modality can be 100% accurate, there remains an argument against using MRI alone.
To conclude, rapid advancements in diagnostic imaging technologies affect the relevancy of recently published research. An example is the use of MRI scanners with stronger magnetic fields of 2.0-3.0T in practice, and even up to 10.5T for research purposes (Eryaman, Y., et al., 2018). Mammography systems have also advanced, with the use of contrast-enhancement improving their diagnostic abilities. Due to its higher specificity values, mammography continues to be a valuable diagnostic modality in breast cancer diagnosis when compared to MRI. There are benefits to both modalities which, when used in combination, can produce a more accurate diagnosis.

References:
Autier, P., and Boniol, M. (2018) Mammography Screening: A major issue in medicine. European Journal of Cancer [online]. 90, pp. 34-62 [Accessed 26 September 2018].
Eryaman, Y., et al. (2018) Investigating the physiological Effects of 10.5 Tesla static field exposure on anaesthetized swine. Magnetic Resonance in Medicine. [online]. 79 pp. 511-514. [Accessed 28 September 2018].
Gilbert, F., et al (2015) The TOMMY trial: a comparison of TOMosynthesis with digital MammographY in the UK NHS Breast Screening Programme – a multicentre retrospective reading study comparing the diagnostic performance of digital breast tomosynthesis and digital mammography with digital mammography alone. National Institute for Health Journal [online]. [Accessed 26 September 2018].
Lee-Felker, S., Tekchandani, L., Thomas, M., Gupta, E., Andrews-Tang, D., Roth, A., Sayre, J., and Rahbar, G. (2017) Newly Diagnosed Breast Cancer: Comparison of Contrast-enhanced Spectral Mammography and Breast MR Imaging in the Evaluation of Extent of Disease. Radiology [online]. 285 (2) [Accessed 26 September 2018].
Maxwell, A., Lim, Y., Hurley, E., Evans, D., Howell, A., and Gadde, S. (2017) False-negative MRI breast screening in high-risk women. Clinical Radiology [online]. 72 (3) pp.207-216. [Accessed 26 September 2018].
Riedl, C., Luft, N., Bernhart, C., Weber, M., Bernathova, M., Tea, M., Rudas, M., Singer, C., and Helbich, T. (2015) Triple-Modality Screening Trial for Familial Breast Cancer Underlines the Importance of Magnetic Resonance Imaging and Questions the Role of Mammography and Ultrasound Regardless of Patient Mutation Status, Age, and Breast Density. Journal of Clinical Oncology [online]. 33 (10), pp. 1128-1135. [Accessed 26 September 2018].

Appendix:
Compilation of research data comparing mammography and magnetic resonance imaging

References	Year(s) of study	Population	Modality	Sensitivity (%)	Specificity (%)	PPV (%)	NPV (%)
Riedl et al. (2015)	Jan 2002-May 2011	559	Mammography U/S	38 38	97 97	28 27	98 98
			MRI	90	89	20	100
			MRI + Mammography	95	88.2	20	100
Lee-Felker et al.(2018)	Mar 2014 – Oct 2015	52	Contrast-enhanced spectral mammography	94	17	93	20
			MRI	99	4	60	67