The Twente Photoacoustic Mammoscope 2: 3D vascular network visualization

Abstract

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.

Semi-anthropomorphic photoacoustic breast phantom

“…10(a)). The PA imaging depth in the phantom was found to be 27 mm, while the imaging depth in healthy volunteer measurements was logged to be 20-22 mm [8,79]. The breast tissue properties of these specific volunteers are unknown, which makes it impossible to make a fair comparison.…”

“…The healthy volunteer is a 29 year-old woman, having a light skin tone. Schoustra et al logged an imaging depth of 20 mm for this healthy volunteer measurement [79] and a depth of 22 mm for a measurement on a 25 year old healthy volunteer [8]. These values were obtained by tracing one of the blood vessels up to the deepest depth where it was still visible.…”

“…Local maximum intensity projections of the PA tomography measurements with the PAM2 system. A) is a medial view of a healthy volunteer measurement as presented in[79] (Reproduced with permission of the authors. Publisher permission sought, in progress).…”

A 3D semi-anthropomorphic photoacoustic breast phantom

“…Additionally, it was imaged with the Twente Photoacoustic Mammoscope 2 (PAM2). 19,20 The phantom was illuminated with 755 nm pulses fired by an Alexandrite laser with a duration of 60 ns. Twelve arc-shaped ultrasound detector arms, each containing 32 elements with a 1 MHz center frequency, rotated 60 degrees around the phantom in 45 steps.…”

Pendant breast immobilization and positioning in photoacoustic tomographic imaging

“…Recently, we described our three-dimensional (3D) tomographic system for photoacoustic breast imaging: PAM 2 [ 25 , 26 ]. In this work, the first human subject measurements with the system were reported, where the breast was imaged while freely pendant inside the imaging tank filled with water.…”