Lipid-weighted intraoperative photoacoustic tomography of breast tumors: Volumetric comparison to preoperative MRI

Ivan Kosik; Muriel Brackstone; Anat Kornecki; Astrid Chamson-Reig; Philip Wong; Jeffrey J L Carson

doi:10.1016/j.pacs.2020.100165

Lipid-weighted intraoperative photoacoustic tomography of breast tumors: Volumetric comparison to preoperative MRI

Photoacoustics. 2020 Apr 24:18:100165. doi: 10.1016/j.pacs.2020.100165. eCollection 2020 Jun.

Authors

Ivan Kosik^{1

2}, Muriel Brackstone^{3

4}, Anat Kornecki^{1

5}, Astrid Chamson-Reig¹, Philip Wong^{1

2}, Jeffrey J L Carson^{1

2

4

6}

Affiliations

¹ Imaging Program, Lawson Health Research Institute, London, Ontario, Canada.
² Department of Medical Biophysics, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario, Canada.
³ Department of Oncology, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, Ontario, Canada.
⁴ Department of Surgery, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, Ontario, Canada.
⁵ Department of Medical Imaging, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario, Canada.
⁶ Department of Physics and Astronomy, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario, Canada.

Abstract

With a lifetime risk of 1 in 8, breast cancer continues to be a major concern for women and their physicians. The optimal treatment of the disease depends on the stage of the cancer at diagnosis, which is typically assessed using medical imaging. However, currently employed imaging systems for breast tumor measurement rarely agree perfectly. Our group developed an Intraoperative Photoacoustic Screening (iPAS) soft tissue scanner featuring high bulk tissue sensitivity, a clinically compatible scan-time of 6 min, imaging depths greater than 2 cm and the capability to visualize whole breast tumors based on their lipid, rather than hemoglobin, profile. Here, we report on the first clinical experience with breast cancer patients by comparing tumor-measurement using iPAS, preoperative dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) and gold-standard pathology. Tumor size was measured volumetrically for iPAS and DCE-MRI, and separately using maximum diameters for pathology, DCE-MRI and iPAS. Comparisons were performed using Pearson's correlation coefficients, and the non-parametric Wilcoxon signed-rank test. Twelve consecutive patients were included in the study, contingent on pathologically documented invasive carcinoma. iPAS volumetric tumor size was positively correlated to DCE-MRI (Pearson's r = 0.78, p = 0.003) and not significantly different (Wilcoxon, p = 0.97). In comparison to pathology, tumor diameters given by iPAS were positively correlated (Pearson's r = 0.87, p = 0.0002) and significantly different (Wilcoxon, p = 0.0015). The results indicated that volumetric-measurement of invasive breast tumors with iPAS is similar to that of DCE-MRI. On the other hand, tumor diameter measurements were less reliable. Beyond enhancing surgical specimen examination, an extension of this technology to diagnostic imaging promises a new perspective on tumor assessment, potentially improving our current understanding and treatment of breast cancer.

Keywords: Acoustic transducers; Breast cancer; Dynamic contrast enhanced MRI; Intraoperative imaging; Lipid weighted imaging; Photoacoustic tomography; Tumor volume.