Photoacoustic Imaging of Breast Microcalcifications: A Preliminary Study with 8-Gauge Core-Biopsied Breast Specimens

Abstract

BackgroundWe presented the photoacoustic imaging (PAI) tool and to evaluate whether microcalcifications in breast tissue can be detected on photoacoustic (PA) images.MethodsWe collected 21 cores containing microcalcifications (n = 11, microcalcification group) and none (n = 10, control group) in stereotactic or ultrasound (US) guided 8-gauge vacuum-assisted biopsies. Photoacoustic (PA) images were acquired through ex vivo experiments by transmitting laser pulses with two different wavelengths (700 nm and 800 nm). The presence of microcalcifications in PA images were blindly assessed by two radiologists and compared with specimen mammography. A ratio of the signal amplitude occurring at 700 nm to that occurring at 800 nm was calculated for each PA focus and was called the PAI ratio.ResultsBased on the change of PA signal amplitude between 700 nm and 800 nm, 10 out of 11 specimens containing microcalcifications and 8 out of 10 specimens without calcifications were correctly identified on blind review; the sensitivity, specificity, accuracy, positive predictive and negative predictive values of our blind review were 90.91%, 80.0%, 85.71%, 83.33% and 88.89%. The PAI ratio in the microcalcification group was significantly higher than that in the control group (the median PAI ratio, 2.46 versus 1.11, respectively, P = .001). On subgroup analysis in the microcalcification group, neither malignant diagnosis nor the number or size of calcification-foci was proven to contribute to PAI ratios.ConclusionBreast microcalcifications generated distinguishable PA signals unlike breast tissue without calcifications. So, PAI, a non-ionizing and non-invasive hybrid imaging technique, can be an alternative in overcoming the limitations of conventional US imaging.

A Pseudo-Dynamic Delay Calculation Using Optimal Zone Segmentation for Ultra-Compact Ultrasound Imaging Systems

“…Recently there have also been arising demands for, and investigations on, compact PA imaging systems [25][26][27], where an efficient beamforming solution is essential [28][29][30]. This may be needed for space-limiting clinical applications such as surgical and interventional guidance [24,[31][32][33]. Moreover, a compact system volume in PA imaging may extend its scientific efficacy.…”

“…Moreover, a compact system volume in PA imaging may extend its scientific efficacy. For example, it may enable an implantable and/or wearable PA neurosensing system for continuous monitoring, leading to successful translations of current neuroscientific findings and neuro-engineering innovations into practice [24][25][26][27][28][29][30][31][32][33][34][35][36].…”

Photoacoustic Imaging: A Novel Tool for Detecting Carotid Artery Thrombosis in Mice

“…A few studies have used PAI to investigate atherosclerosis plaques [17,18] as well as to detect breast tumors [19] and melanoma [20]. Thus, PAI not only resolves anatomical contrasts but can also visualize hemoglobin [6,21,22,23], melanin [20], lipids [17,18], and a wide variety of optical agents [24,25,26,27,28].…”

Intraoperative photoacoustic screening of breast cancer: a new perspective on malignancy visualization and surgical guidance

“…The success of this technique is in large part due to its ability to sway imaging contrast toward specific tissue chromophores, such as oxyhemoglobin, deoxyhemoglobin, lipid or calcium oxalate, and hydroxyapatite (i.e., microcalcifications). [20][21][22] Furthermore, PAT overcomes limited depth penetration by ultrasonically encoding deep tissue optical contrast and, therefore, similar to diagnostic US, is able to achieve several centimeters of penetration and near millimeter, or submillimeter, resolution. [23][24][25] In spite of these favorable properties, PAT has rarely been evaluated for surgical intervention and only recently for assessing breast lumpectomy margins.…”