We present the Twente Photoacoustic Mammoscope 2, a photoacoustic breast imaging system employing a tomographic configuration. It images one breast pendant inside an imaging tank filled with water while a woman lies prone on a bed. A dual-head laser (755 and 1064 nm) illuminates the breast with one beam directed at the nipple and nine beams directed at the sides. Ultrasound signals are detected using 12 arc-shaped arrays, each curving along the pendant breast. Each array comprises 32 piezocomposite elements each with a center frequency of 1 MHz. The imaging tank and the ultrasound arrays rotate around the breast in steps to obtain additional multiple projections. Three-dimensional images are reconstructed using a filtered backprojection algorithm. The system is described in detail, and measurements on a test object are presented. As part of a preliminary study to assess the system’s in vivo performance, the breasts of two healthy volunteers were imaged. These images show the breast contour, the nipple, and the vascular anatomy within the breast. In the nipple of one case, multiple high-intensity “hot spots” are observed, which we suspect are associated with the lactiferous ducts terminating in the nipple.
We present the Twente Photoacoustic Mammoscope 2 (PAM 2) based on a 3D tomographic geometry. A functional optical contrast map of breast vascularization can be obtained in a noninvasive, radiation-free and painless manner. A woman lies prone on a bed with one breast pendant in an imaging tank with water, where 12 curved ultrasound arrays are mounted. Each array extends from chest wall towards the nipple following the contour of the pendant breast, and carries 32 detector elements. The detectors’ center frequency is 1 MHz. The breast is illuminated from multiple directions: the ventral side of the breast from the bottom and the areas close to the chest wall from the sides. The excitation wavelengths are 755 nm and 1064 nm. By rotating the imaging tank in between measurements, multiple projections can be obtained, providing a 3D image of the breast after reconstruction by means of a filtered backprojection. So far, breasts of healthy volunteers were imaged. Three-dimensional images of the breast contour, the nipple and blood vessel networks within the breast could be observed with high contrast and unprecedented detail.