Evaluating Thin Compression Paddles for Mammographically Compatible Ultrasound

Abstract

We are developing a combined digital mammography/3D ultrasound system to improve detection and/or characterization of breast lesions. Ultrasound scanning through a mammographic paddle could significantly reduce signal level, degrade beam focusing, and create reverberations. Thus, appropriate paddle choice is essential for accurate sonographic lesion detection and assessment with this system. In this study, we characterized ultrasound image quality through paddles of varying materials (lexan, polyurethane, TPX, mylar) and thicknesses (0.25-2.5 mm). Analytical experiments focused on lexan and TPX, which preliminary results demonstrated were most competitive. Spatial and contrast resolution, sidelobe and range lobe levels, contrast and signal strength were compared with no-paddle images. When the beamforming of the system was corrected to account for imaging through the paddle, the TPX 2.5 mm paddle performed the best. Test objects imaged through this paddle demonstrated ≤ 15% reduction in spatial resolution, ≤ 7.5 dB signal loss, ≤ 3 dB contrast loss, and range lobe levels ≥ 35 dB below signal maximum over 4 cm. TPX paddles < 2.5 mm could also be used with this system, depending on imaging goals. In 10 human subjects with cysts, small CNR losses were observed but were determined to be statistically insignificant. Radiologists concluded that 75% of cysts in through-paddle scans were at least as detectable as in their corresponding directcontact scans.

Digital Breast Tomosynthesis: State of the Art

“…An initial study (151) combined FFDM with three-dimensional automated breast US enabling coregistered dual-modality imaging and was subsequently modified for DBT with automated breast US. Development of a compression paddle compatible for both x-ray and US imaging (152), selection of US coupling media, and breast coverage with US particularly at the breast periphery that is not in contact with the compression paddle have been reported (153). In an analysis of 51 patients with masses (13 malignancies), Padilla et al (154) reported similar AUCs for DBT alone and the combined DBT and automated breast US, and an improvement in discriminating masses from simple cysts.…”

Automated Breast Ultrasound: Dual-Sided Compared with Single-Sided Imaging

“…Automated elasticity imaging (Booi 2007, Booi, et al 2007) and local compression by the scanning transducer (Carson, et al 2010) also are possible with this type of system. Quasi-static elasticity studies were performed earlier (Booi 2007, Booi, et al 2007) with solid, rather than mesh paddles.…”

“…Quasi-static elasticity studies were performed earlier (Booi 2007, Booi, et al 2007) with solid, rather than mesh paddles. Compression of the entire breast by the paddles, to stabilize the breast position, provided preloading of all the tissues.…”

“…This could make the analysis easier, possibly increasing sensitivity and decreasing callback rates. Combined systems for this purpose have been studied (Besson and Nields, Dines, et al, Dines 1995, Kapur, et al 2004, Padilla, et al 2013, Richter 1997, Schmidt, et al 2006, Schutze 1998, Shmulewitz, 1995, Shmulewitz, 1996, Smith 2014, Suri, et al 2005) and improved to increase image quality, breast stability between the compression paddles and the effectiveness of acoustic gel coupling (Booi, et al 2007, Kapur, Thomenius, LeCarpentier, et al 2014, Li, et al 2010, Sinha, et al 2007). …”

Robot guidance of an ultrasound probe toward a 3D region of interest detected through X-ray mammography

“…As for the breast, a multi modal breast phantom (Cirs inc. model 051 phantom) containing dense masses of 2 to 8 mm diameter and cystic lesions of 3 to 10 mm diameter is used. It is compressed between a 25 mm thick PVC plate (at the bottom) and a 6 mm thick PMP plate (at the top), both well suited regarding their low x-ray attenuation, PMP being equally well suited to let pass US [4]. Figure 6 show typical US-image of a lesion obtained with this set-up.…”