Detection of involved margins in breast specimens with X-ray phase-contrast computed tomography

Abstract

Margins of wide local excisions in breast conserving surgery are tested through histology, which can delay results by days and lead to second operations. Detection of margin involvement intraoperatively would allow the removal of additional tissue during the same intervention. X-ray phase contrast imaging (XPCI) provides soft tissue sensitivity superior to conventional X-rays: we propose its use to detect margin involvement intraoperatively. We have developed a system that can perform phase-based computed tomography (CT) scans in minutes, used it to image 101 specimens approximately half of which contained neoplastic lesions, and compared results against those of a commercial system. Histological analysis was carried out on all specimens and used as the gold standard. XPCI-CT showed higher sensitivity (83%, 95% CI 69–92%) than conventional specimen imaging (32%, 95% CI 20–49%) for detection of lesions at margin, and comparable specificity (83%, 95% CI 70–92% vs 86%, 95% CI 73–93%). Within the limits of this study, in particular that specimens obtained from surplus tissue typically contain small lesions which makes detection more difficult for both methods, we believe it likely that the observed increase in sensitivity will lead to a comparable reduction in the number of re-operations.

Volumetric High-Resolution X-Ray Phase-Contrast Virtual Histology of Breast Specimens With a Compact Laboratory System

“…Conventional techniques such as optical microscopy or spectroscopy provide volumetric information but have, in general, a reduced penetration depth, hindering their application to large specimens such as large wide local excisions or mastectomies [4], [5]. On the other hand, while X-rays are one of the methods of choice for breast cancer screening, their application to intra and post-operative assessment of breast specimens is still the subject of investigations [6], [7]. The main limitation is that, while conventional Xray imaging provides sufficient penetration depth and good spatial resolution, it provides limited soft tissue contrast if staining agents are not used, which affects its application to biomedical imaging.…”

Composite porosity characterization using x-ray edge illumination phase contrast and ultrasonic techniques

“…When a sample is placed in the beam, the X-rays change their direction of propagation due to refraction [26]. The used system [27] included a Rigaku MicroMax 007 HF rotating anode molybdenum source with a 70 µm focal spot, operating at 40 kVp and 20 mA. The detector was an indirect flat panel CMOS detector with a 50 x 50 µm 2 pixel size.…”

Exploring the potential of cycloidal computed tomography for advancing intraoperative specimen imaging

“…Experimental studies have demonstrated the ability of x-ray phase contrast imaging to yield a higher contrast-to-noise ratio (CNR) than conventional attenuation-based x-ray imaging. In particular, this applies to samples with weak intrinsic x-ray attenuation such as soft biological tissue [13][14][15][16] , a category that includes surgically excised human tissue, which explains why the technology is receiving attention in the context of intraoperative specimen imaging [3][4][5]17 .…”

“…Our group has developed dedicated x-ray phase contrast micro-computed tomography (CT) scanners for the intraoperative margin assessment of resected tumours [3][4][5] . These implement "edge-illumination" (EI), utilising masks to generate separated x-ray beamlets and analyse their refraction.…”