Impact of Magnification Views on the Characterization of Microcalcifications in Digital Mammography

Abstract

Purpose: To evaluate the additional benefit of true geometric (air-gap) magnification views for the characterization of microcalcifications in digital mammography.

Materials and Methods: After ethical approval, we retrospectively reviewed patient records to identify 100 patients with suspicious microcalcifications (35 malignant, 65 benign) who had a standard digital mammography and an additional digital magnification view in the same projection within three months. All images were obtained using an amorphous silicon-based full-field digital system (Senographe 2000 D, GE Healthcare, Chalfont St. Giles, UK). Images were independently analyzed by six board-certified radiologists. The probability of malignancy was estimated using first standard contact mammography alone (MG) and then mammography in combination with the magnification view (MG+MAG) using a modified Breast Imaging Reporting and Data System (BI-RADS) classification system and a percentage scale. Results were compared using receiver operating characteristic (ROC) analysis. In addition, readers assessed the subjective visibility of the calcifications.

Results: For all six readers combined, the area under the curve (AUC) was 0.664 ± 0.052 for MG and 0.813 ± 0.042 for MG + MAG, resulting in a statistically significant improvement of 0.148 ± 0.120. Each reader had a higher AUC for MG + MAG than MG, with the improvement being statistically significant in four of the six readers. In 76.34 % of the cases, MG + MAG resulted in better visibility of calcifications compared with mammography alone. In 33 % slightly more and in 39 % significantly more calcifications were found.

Conclusion: Even in digital mammography with the option of using electronic magnification (zoom) at the viewing workstation, true geometric (air-gap) magnification views remain important for the visibility and correct classification of microcalcifications and for the assessment of their extent.

Citation Format:

• Fallenberg EM, Dimitrijevic L, Diekmann F et al. Impact of Magnification Views on the Characterization of Microcalcifications in Digital Mammography. Fortschr Röntgenstr 2014; 186: 274 – 280

Zusammenfassung

Ziel: Evaluation des Nutzen geometrischer Vergrößerungsaufnahmen für die Charakterisierung von Mikroverkalkungen in der digitalen Mammografie.

Material und Methode: Nach positivem Ethikvotum selektierten wir retrospektiv anhand der Befundberichte 100 Patienten mit suspekten Mikroverkalkungen (35 maligne, 65 benigne), die innerhalb von 3 Monaten eine Standardmammografie (MG) und eine Vergrößerungsaufnahme (MAG) in der gleichen Ebene bekommen haben. Alle Aufnahmen wurden an einem Volldetektor-System (Senografe 2000 D, GE Healthcare, Chalfont St. Giles, UK) erstellt. Die Bilder wurden von 6 unabhängigen Radiologen analysiert. Die Malignitätswahrscheinlichkeit der MG alleine und dann folgend der MG plus MAG wurde bestimmt. Die Ergebnisse wurden mittels ROC-Analyse verglichen. Zusätzlich wurde die Sichtbarkeit der Verkalkungen beurteilt.

Ergebnisse: Die Area under curve (AUC) betrug für alle Reader kombiniert 0,664 ± 0,052 für MG und 0,813 ± 0,042 für MG + MAG, einer signifikante Verbesserung von 0,148 ± 0,120 entsprechend. Jeder Reader erreichte eine höhere AUC für MG + MAG als für MG, diese Verbesserung war bei vier Readern signifikant. In 76,34 % der Fälle zeigte MG + MAG eine bessere Sichtbarkeit der Kalzifikationen. Bei 33 % waren gering mehr, bei 39 % deutlich mehr Verkalkungen abgrenzbar.

Schlussfolgerung: Auch bei Einsatz der digitalen Mammografie mit den Möglichkeiten der elektronischen Vergrößerung bei Bildschirm-Befundung kann nicht auf geometrische Vergrößerungsaufnahmen verzichtet werden, da diese für die korrekte Klassifizierung und Ausdehnungsbeurteilung von Mikroverkalkungen weiterhin wichtig sind.

Key words

breast - breast radiography - screening - mammography - microcalcifications

• References

• 1 Weigel S, Decker T, Korsching E et al. Calcifications in digital mammographic screening: improvement of early detection of invasive breast cancers?. Radiology 2010; 255: 738-745
• 2 Moon WK, Im JG, Koh YH et al. US of mammographically detected clustered microcalcifications. Radiology 2000; 217: 849-854
• 3 Skaane P, Skjennald A. Screen-film mammography versus full-field digital mammography with soft-copy reading: randomized trial in a population-based screening program--the Oslo II Study. Radiology 2004; 232: 197-204
• 4 Skaane P, Hofvind S, Skjennald A. Randomized trial of screen-film versus full-field digital mammography with soft-copy reading in population-based screening program: follow-up and final results of Oslo II study. Radiology 2007; 244: 708-717
• 5 Skaane P, Balleyguier C, Diekmann F et al. Breast lesion detection and classification: comparison of screen-film mammography and full-field digital mammography with soft-copy reading--observer performance study. Radiology 2005; 237: 37-44
• 6 Pisano ED, Gatsonis C, Hendrick E et al. Diagnostic performance of digital versus film mammography for breast-cancer screening. N Engl J Med 2005; 353: 1773-1783
• 7 Obenauer S, Hermann KP, Schorn C et al. Digitale Vollfeldmammographie: Phantomstudie zur Detektion von Mikrokalk. [Full-field digital mammography: a phantom study for detection of microcalcification]. Fortschr Röntgenstr 2000; 172: 646-650
• 8 Rominger M, Wisgickl C, Timmesfeld N. Breast microcalcifications as type descriptors to stratify risk of malignancy: a systematic review and meta-analysis of 10665 cases with special focus on round/punctate microcalcifications. Fortschr Röntgenstr 2012; 184: 1144-1152
• 9 Kettritz U, Morack G, Decker T. Stereotactic vacuum-assisted breast biopsies in 500 women with microcalcifications: radiological and pathological correlations. Eur J Radiol 2005; 55: 270-276
• 10 Sickles EA. Mammographic detectability of breast microcalcifications. Am J Roentgenol Am J Roentgenol 1982; 139: 913-918
• 11 Sickles EA. Further experience with microfocal spot magnification mammography in the assessment of clustered breast microcalcifications. Radiology 1980; 137: 9-14
• 12 Oestmann JW, Kopans DB, Linetsky L et al. Comparison of two screen-film combinations in contact and magnification mammography: detectability of microcalcifications. Radiology 1988; 168: 657-659
• 13 Law J. Breast dose from magnification films in mammography. Br J Radiol 2005; 78: 816-820
• 14 Diekmann F, Diekmann S, Bick U et al. Vergleich der Visualisierung von Mikroverkalkungen durch Vergrosserungsaufnahmen in digitaler Vollfeldmammographie und konventioneller Mammographie. [Comparing the visualization of microcalcifications with direct magnification in digital full-field mammography vs. film-screen mammography]. Fortschr Röntgenstr 2002; 174: 297-300
• 15 Fischer U, Baum F, Obenauer S et al. Digitale Vollfeldmammographie: Vergleich zwischen radiographischer Direktvergrösserung und digitalem Monitorzooming. [Digital full field mammography: comparison between radiographic direct magnification and digital monitor zooming]. Radiologe 2002; 42: 261-264
• 16 Elston CW, Ellis IO. Pathological prognostic factors in breast cancer. I. The value of histological grade in breast cancer: experience from a large study with long-term follow-up. Histopathology 1991; 19: 403-410
• 17 Carl JDO. Radiology ACo, Committee ACoRB-R. . Illustrated Breast Imaging Reporting and Data System (Illustrated BI-RADS). American College of Radiology; 1998
• 18 Metz CE. ROC methodology in radiologic imaging. Invest Radiol 1986; 21: 720-733
• 19 Schueler S, Schuetz GM, Hamm B et al. Lesen und Interpretieren von Metaanalysen diagnostischer Genauigkeitsstudien. [Reading and interpreting meta-analyses of diagnostic accuracy studies]. Fortschr Röntgenstr 2011; 183: 799-803
• 20 Kim MJ, Kim EK, Kwak JY et al. Characterization of microcalcification: can digital monitor zooming replace magnification mammography in full-field digital mammography?. Eur Radiol 2009; 19: 310-317
• 21 Kim MJ, Youk JH, Kang DR et al. Zooming method (× 2.0) of digital mammography vs digital magnification view (×1.8) in full-field digital mammography for the diagnosis of microcalcifications. Br J Radiol 2010; 83: 486-492
• 22 Moraux-Wallyn M, Chaveron C, Bachelle F et al. Comparison between electronic zoom and geometric magnification of clusters of microcalcifications on digital mammography. J Radiol 2010; 91: 879-883
• 23 Kimme-Smith C, Gold RH, Bassett LW et al. Diagnosis of breast calcifications: comparison of contact, magnified, and television-enhanced images. Am J Roentgenol Am J Roentgenol 1989; 153: 963-967
• 24 European Society of R. White paper on radiation protection by the European Society of Radiology. Insights into imaging. 2011; 2: 357-362
• 25 Weigel S, Girnus R, Czwoydzinski J et al. Digital mammography screening: average glandular dose and first performance parameters. Fortschr Röntgenstr 2007; 179: 892-895
• 26 Ruschin M, Hemdal B, Andersson I et al. Threshold pixel size for shape determination of microcalcifications in digital mammography: a pilot study. Radiat Prot Dosimetry 2005; 114: 415-423
• 27 Karssemeijer N, Bluekens AM, Beijerinck D et al. Breast cancer screening results 5 years after introduction of digital mammography in a population-based screening program. Radiology 2009; 253: 353-358
• 28 Cowen AR, Launders JH, Jadav M et al. Visibility of microcalcifications in computed and screen-film mammography. Phys Med Biol 1997; 42: 1533-1548
• 29 Lai C-J, Shaw CC, Whitman GJ et al. Visibility of simulated microcalcifications--a hardcopy-based comparison of three mammographic systems. Med Phys 2005; 32: 182-194