Strain Elastography: A Valuable Additional Method to BI-RADS?

Abstract

Background Breast lesions classified as BI-RADS-US 3 are probably benign and observation was recommended, while a considerable number of BI-RADS-US 4 lesions were benign, resulting in excessive biopsies. We focus exclusively on BI-RADS-US 3 and 4 lesions and hypothesize that improved diagnostic performance can be achieved by integrating real-time elastography (strain ratio) into the BI-RADS-US classification system.

Method From April 2010 to September 2015, 1071 lesions were included in the final analysis. After the conventional ultrasound examination, the BI-RADS-US (2013) classification was used to evaluate the lesions. Then the strain ratios were calculated, and the final diagnosis was made on the basis of histological results. The sensitivity, specificity, accuracy, PPV and NPV were calculated and the AUCs were compared. Additionally, an analysis of the diagnostic performance expressed by the pretest and posttest probability of disease (POD) was performed in BI-RADS-US 3 and 4A lesions.

Results With the cutoff point of 2.98, the sensitivity, specificity and accuracy of the strain ratio method were 86.9 %, 86.6 % and 82.6 %, respectively. In BI-RADS-US 3 lesions, a suspicious strain ratio significantly modified the POD from 1.3 % to a posttest POD of 29.8 %. In BI-RADS-US 4A lesions, a suspicious strain ratio significantly modified the POD from 8.5 % to a posttest POD of 48.7 %.

Conclusion Ultrasonographic elastography (strain ratio) yields additional diagnostic information in the evaluation of BI-RADS-US 3 and 4 breast lesions. The strain ratios should be integrated into the BI-RADS-US classification system and into daily practice.

Zusammenfassung

Hintergrund Herdbefunde der Brust, die mit BI-RADS-US Kategorie 3 bewertet wurden, sind vermutlich gutartig und eine Kontrolle wurde empfohlen, während solche mit BI-RADS-US Kategorie 4 in beträchtlichem Maße gutartig waren, was zu übermäßigen Biopsien führte. Unser Fokus gilt ausschließlich den Herdbefunden der BI-RADS-US Kategorie 3 und 4 und wir vermuten, dass die diagnostische Leistung durch Aufnahme der Echtzeit-Elastografie (Strain-Ratio) in die BI-RADS-US-Befund-Kategorien verbessert werden kann.

Methoden Von April 2010 bis September 2015 wurden 1071 Herdbefunde in die Endanalyse aufgenommen. Nach Durchführung der konventionellen Sonografie wurden die BI-RADS-US-Kategorien (2013) zur Bewertung der Herdbefunde angewandt. Dann wurden die Strain-Ratios berechnet, die Enddiagnose wurde histologisch gesichert. Sensitivität, Spezifität, Genauigkeit, PPW und NPW wurden berechnet und die AUCs wurden verglichen. Zusätzlich wurde bei den BI-RADS-US 3 und 4A Herdbefunden eine Analyse der diagnostischen Leistung mittels Prätest- und Posttest-POD („probability of disease“) durchgeführt.

Ergebnis Bei einem Grenzwert von 2,98 erzielte die Strain-Ratio-Methode eine Sensitivität von 86,9 %, eine Spezifität von 86,6 % und eine Genauigkeit von 82,6 %. Bei BI-RADS-US 3-Herdbefunden führte eine auffällige Strain-Ratio zu einer signifikanten Veränderung der POD von 1,3 % auf 29,8 % (Posttest). Bei BI-RADS-US 4A-Herdbefunden veränderte eine auffällige Strain-Ratio die POD signifikant von 8,5 % auf 48,7 % (Posttest).

Schlussfolgerung Die Ultraschall-Elastografie (Strain-Ratio) liefert zusätzliche diagnostische Informationen bei der Bewertung von Herdbefunden der Brust bei BI-RADS-US Kategorien 3 und 4. Die Strain-Ratio sollte in die BI-RADS-US-Befund-Kategorien und in die tägliche Praxis aufgenommen werden.

Key words

breast radiography - strain elastography - BI-RADS - breast cancer - strain ratio

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