Selenia dimension

This study was approved by the Cyprus National Bioethics Committee. The patient cohort was from a single centre, the Bank of Cyprus Oncology Center (BOCOC, Nicosia, Cyprus). Surveillance imaging at the Centre is offered to any breast cancer patient who undergoes breast cancer treatment including breast conserving surgery or mastectomy with or without post-operative radiotherapy and systemic therapy.
Surveillance imaging at the BOCOC is carried out annually using the commercial DBT system, Hologic Selenia Dimensions (Hologic Inc., Bedford, MA, USA), using the 2-view (or ‘combo’) mode: for each patient 2-view (CC and MLO) DM and 2-view (CC and MLO) DBT images are acquired. Fifteen projections over an angular range of 15° are acquired and reconstructed using filtered back projection.
The patient inclusion criteria of this study included (i) women aged 18 years old or above, (ii) who attended mammography surveillance imaging (before the commencement, and independently of this study) at the BOCOC between September 2014 and December 2017 under the local mammography surveillance imaging protocol described above, (iii), following breast cancer treatment at the same centre. Patients with breast implants were excluded from the patient cohort.

The mammography study was conducted with freshly dissected mastectomy specimens according to the Declaration of Helsinki and after the approval of the local ethics committee. After a detailed explanation of the study protocol, the patients gave their written consent before participating in the study. Before the experimental measurements and for a better comparison of the results, clinical in vivo and ex vivo images were acquired. The clinical ex vivo measurements were performed in a cranio-caudal (CC) or anteroposterior (AP) position with the specimen fixed in a metal-framed specimen holder to simulate breast compression. The clinical in vivo and ex vivo mammography images were both taken with a device by Hologic (Marlborough, USA) called Selenia Dimensions whose pixel size is $70\times 70\mu {\mathrm{m}}^2$ .

All CEM images from both institutes were acquired using a mammography system (Selenia Dimensions, Hologic) with dual-energy exposure. The contrast medium Omnipaque 350 (GE Healthcare Inc) was injected into patients via an automatic power injector (Vistron CT injection system, Medrad) at a volume of 1.5 ml/kg of body weight and a rate of 3 ml/s through a peripheral intravenous cannula. After completion, patients were disconnected from the automatic power injector.
The CEM images were obtained starting at 2 min after contrast medium injection. Mediolateral oblique (MLO) and craniocaudal (CC) views of the breast with the lesion of concern would be obtained first, followed by CC and MLO views of the contralateral breast. Two exposures, one at high energy (45–49 kVp) and another at low energy (26–32 kVp), were performed almost simultaneously for each view, and a recombined image between the two was generated to visualize contrast enhancement of both breasts. The image of all 4 views was acquired between 2 and 7 min after contrast agent injection. The pre-surgery bilateral CEM should be performed within 7 min to avoid the influence of greater fibroglandular enhancement on delayed imaging to cancer differentiation in the contralateral breast

This study used a DBT system (Selenia Dimensions; Hologic Inc., Bedford, MA, USA) that consists of an X-ray tube with a 0.3 mm focal spot (tube target: W, filtration: 0.7 mm aluminum equivalent) and a digital flat-panel amorphous selenium detector. A total acquisition time of 3.7 s and an acquisition angle of 15° were set for all DBT procedures. The projection images were sampled during a single tomographic pass (15 projections, 1280 × 2048 matrix). To produce reconstructed tomograms of the required height, we used a 512 × 1024 matrix with 32 bits (single-precision floating number) per image.