ShearWave™ Elastography BE1 Multinational Breast Study: Additional SWE™ Features Support Potential to Downgrade BI-RADS^®-3 Lesions

Abstract

Purpose: To determine the benefit of ShearWave™ Elastography (SWE™) in the ultrasound characterization of BI-RADS^® 3 breast lesions in a diagnostic population.

Materials and Methods: 303 BI-RADS^® 3 lesions (mean size: 13.2 mm, SD: 7.5 mm) from the multicenter BE1 prospective study population were analyzed: 201 (66 %) had cytology or core biopsy, and the remaining 102 had a minimum follow-up of one year; 8 (2.6 %) were malignant. 7 SWE features were evaluated with regard to their ability to downgrade benign BI-RADS^® 3 masses. The performance of each SWE feature was assessed by evaluating the number of lesions correctly reclassified and the impact on cancer rates within the new BI-RADS^® 3‘ lesion group. 

Results: No malignancies were found with an E-color “black to dark blue”, which allowed the downgrading of 110/303 benign masses (p < 0.0001), with a non-significant increase in BI-RADS^® 3‘ malignancy rate from 2.6 % to 4.1 %. E-max ≤ 20kPa (2.6 m/s) was able to downgrade 48/303 (p < 0.0001) lesions with a lower increase in BI-RADS^® 3‘ malignancy rate (3.1 %). No other SWE features were useful for reclassifying benign BI-RADS^® 3 lesions.

Conclusion: Applying simple reclassification rules, SWE assessment of the maximum stiffness of lesions allowed the downgrading of a sub-group of benign BI-RADS^® 3 lesions. This was accompanied by a non-significant increase in the malignancy rate in the new BI-RADS^® 3 class.

Zusammenfassung

Ziel: Evaluation der Scherwellen-Elastografie (SWE) zur näheren Charakterisierung von BI-RADS^®-3 Läsionen in der Mamma.

Material und Methoden: Insgesamt wurden 303 BI-RADS^®-3 Läsionen (Durchschnitt der Größe: 13,2 mm, Standardabweichung: 7,5 mm) aus dem Studienkollektiv der prospektiven BE1 Multicenter-Studie analysiert. 201/303 (66 %) Läsionen wurden minimalinvasiv zytologisch oder histologisch abgeklärt, bei 102/303 (33 %) lag ein Follow-up von mind. 1 Jahr vor. 8/303 (2,6 %) Läsionen waren maligne. Sieben verschiedene SWE-Kriterien wurden hinsichtlich ihres Einflusses auf eine korrekte Reklassifikation von BI-RADS^®-3 Läsionen und eine mögliche Herabstufung auf eine neue Klassifikation BI-RADS^®-3’ untersucht.

Ergebnisse: Keine malignen Befunde ergaben sich für das Kriterium Elastografie-Farbe (E color) „schwarz bis dunkelblau“, was ein Downgrading von 110/303 Läsionen erlaubte (p < 0,0001); nicht signifikanter Anstieg der Malignitätsrate in der neuen BI-RADS-3^®’ Klassifikation von 2,6 % auf 4,1 %. Mit dem Zusatzkriterium maximale Elastizität (E Max) ≤ 20kPa (2,6 m/s) konnten 48/303 Läsionen reklassifiziert werden (p < 0,0001); geringerer nicht signifikanter Malignitätsanstieg von 2,6 % auf 3,1 %. Die übrigen SWE-Kriterien waren nicht geeignet für eine Reklassifikation der BI-RADS^®-3 Läsionen.

Schlussfolgerungen: Die Anwendung einfacher Reklassifikationsregeln wie der maximalen Elastizität erlauben ein sicheres Downgrading von BI-RADS^®-3 Läsionen in eine neue BI-RADS^®-3’ Untergruppe, ohne das es zu einem signifikanten Malignitätsanstieg kommt.

Key words

breast - ultrasound - diagnostic radiology - tumor

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