Diagnostic performance of tomosynthesis, digital mammography and a dedicated digital specimen radiography system versus pathological assessment of excised breast lesions

Abstract

Background: The aim of the study was to compare the performance of full-field digital mammography (FFDM), digital breast tomosynthesis and a dedicated digital specimen radiography system (SRS) in consecutive patients, and to compare the margin status of resected lesions versus pathological assessment.

Patients and methods: Resected tissue specimens from consecutive patients who underwent intraoperative breast specimen assessment following wide local excision or oncoplastic breast conservative surgery were examined by FFDM, tomosynthesis and SRS. Two independent observers retrospectively evaluated the visibility of lesions, size, margins, spiculations, calcifications and diagnostic certainty, and chose the best performing method in a blinded manner.

Results: We evaluated 216 specimens from 204 patients. All target malignant lesions were removed with no tumouron-ink. One papilloma had positive microscopic margins and one patient underwent reoperation owing to extensive in situ components. There were no significant differences in measured lesion size among the three methods. However, tomosynthesis was the most accurate modality when compared with the final pathological report. Both observers reported that tomosynthesis had significantly better lesion visibility than SRS and FFDM, which translated into a significantly greater diagnostic certainty. Tomosynthesis was superior to the other two methods in identifying spiculations and calcifications. Both observers reported that tomosynthesis was the best performing method in 76.9% of cases. The interobserver reproducibilities of lesion visibility and diagnostic certainty were high for all three methods.

Conclusions: Tomosynthesis was superior to SRS and FFDM for detecting and evaluating the target lesions, spiculations and calcifications, and was therefore more reliable for assessing complete excision of breast lesions.

Keywords: breast cancer; digital breast tomosynthesis; mammography; radiography; surgery.

Figure 1

Specimen radiographs of a spiculated invasive ductal carcinoma excised after ultrasound guidewire localisation. The tumour and spicules are clearly visible in all three imaging modalities (closed arrows). (A) Specimen radiography system, (B) full-field digital mammography and (C) tomosynthesis (1 mm reconstructed image at the level of the tumour). Metal clips indicate the anatomical position (open arrows; 1 clip-lateral and 2 clips-medial). The position of the specimen is constant in all three imaging modalities.

Figure 2

A 44-year-old female presented with a 5 × 4.5 cm multifocal invasive lobular carcinoma and underwent supine magnetic resonance imaging-guided oncoplastic conservative resection. Although the irregular area of the tumour (thick arrows) is visible on the specimen radiography system (A) and full-field digital mammography (B) images, the tumour margins are best delineated by tomosynthesis (C) (1 mm reconstructed image at the level of the tumour). The pleomorphic lobular carcinoma in situ is clearly depicted by tomosynthesis as an area of linear calcifications (thin arrows). The shortest margins at imaging were 4 mm (open arrow; superior) and 5 mm at final pathology. The fascia at the level of tumour was removed separately (dotted arrow).

Figure 3

A 68-year-old female presented with invasive ductal carcinoma, papillary ductal carcinoma in situ, and papillomatosis, and underwent oncoplastic conservative breast resection. (A) Shows the excised skin area above the tumour that was deemed not visible by both observers on the specimen radiography system image (B). (C) Full-field digital mammography shows a small oval lesion (arrow). (D) Tomosynthesis (1 mm reconstructed image) shows the full extension of the large spiculated area (arrows).

Figure 4

Bland-Altman plots of tumour diameters compared with the pathological report, as measured by observer 1 (A–C) and observer 2 (D–F) using tomosynthesis (A,D), specimen radiography system (B,E), and full-field digital mammography (C,F).