title: 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 to 2.5 mm). Analytical experiments focused on lexan and TPX, which preliminary results demonstrated were most competitive. Spatial and contrast resolution, side-lobe 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 < or = 15% reduction in spatial resolution, < or = 7.5 dB signal loss, < or = 3 dB contrast loss and range lobe levels > or = 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 direct-contact scans.
authors.affiliation: Department of Radiology, University of Michigan, Ann Arbor, MI, USA. rbooi@umich.edu
authors.forename: Rebecca C
authors.initials: RC
authors.lastname: Booi
authors.forename: Jochen F
authors.initials: JF
authors.lastname: Krücker
authors.forename: Mitchell M
authors.initials: MM
authors.lastname: Goodsitt
authors.forename: Matthew
authors.initials: M
authors.lastname: O'Donnell
authors.forename: Ajay
authors.initials: A
authors.lastname: Kapur
authors.forename: Gerald L
authors.initials: GL
authors.lastname: LeCarpentier
authors.forename: Marilyn A
authors.initials: MA
authors.lastname: Roubidoux
authors.forename: J Brian
authors.initials: JB
authors.lastname: Fowlkes
authors.forename: Paul L
authors.initials: PL
authors.lastname: Carson
mesh_terms: D000273:Adipose Tissue / Q000000981:diagnostic imaging; D047688:Breast Cyst / Q000000981:diagnostic imaging; D001941:Breast Diseases / Q000000981:diagnostic imaging*; D004867:Equipment Design; D005260:Female; D006801:Humans; D011093:Polyethylene Terephthalates; D011108:Polymers; D011140:Polyurethanes; D011787:Quality of Health Care; D014465:Ultrasonics; D016217:Ultrasonography, Mammary / Q000295:instrumentation*
chemical_list: D011093:Polyethylene Terephthalates; D011108:Polymers; D011140:Polyurethanes; C017902:lexan; C025539:Lavsan