Investigating the feasibility of a hand-held photoacoustic imaging probe for margin assessment during breast conserving surgery

E Rascevska; L C M Yip; P Omidi; M Brackstone; J J L Carson

doi:10.1016/j.pacs.2022.100424

Investigating the feasibility of a hand-held photoacoustic imaging probe for margin assessment during breast conserving surgery

Photoacoustics. 2022 Oct 31:28:100424. doi: 10.1016/j.pacs.2022.100424. eCollection 2022 Dec.

Authors

E Rascevska^{1

2}, L C M Yip^{1

3}, P Omidi^{1

2}, M Brackstone^{4

5}, J J L Carson^{1

2

4

3}

Affiliations

¹ Imaging Program, Lawson Health Research Institute, 268 Grosvenor St., London N6A 4V2, ON, Canada.
² School of Biomedical Engineering, Western University, 1151 Richmond St., London N6A 3K7, ON, Canada.
³ Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, 1151 Richmond St., London N6A 3K7, ON, Canada.
⁴ Department of Surgery, Schulich School of Medicine and Dentistry, Western University, 1151 Richmond St., London N6A 3K7, ON, Canada.
⁵ Department of Oncology, Schulich School of Medicine & Dentistry, The University of Western Ontario, 1151 Richmond St., N6A 3K7, London, ON, Canada.

Abstract

Approximately 19 % of breast cancer patients undergoing breast conserving surgery (BCS) must return for a secondary surgery due to incomplete tumour removal. Our previous work demonstrated that the lower lipid content, characteristic of tumour tissue, was observed as regions of hypo-intense photoacoustic (PA) contrast. The goal of this work was to evaluate feasibility of a low-frequency, hand-held PA imaging probe for surgical margin assessment based on lipid content differences. Here, we describe (i) the design of a prototype hand-held PA imaging probe, (ii) the effect of limited-bandwidth on image contrast, (iii) accuracy towards hypo-intense contrast detection, (iv) the limited-view characteristics of the single sensor design, and (iv) early imaging results of an ex-vivo breast cancer specimen. The probe incorporates a single polyvinylidene fluoride acoustic sensor, a 1-to-4 optical fibre bundle and a polycarbonate axicon lens for light delivery. Imaging results on phantoms designed to mimic positive margins demonstrated the ability to detect gaps in optical absorption as small as 1 mm in width. Compared to images from a near full-view PAI system, the hand-held PAI probe had higher signal to noise ratio but suffered from negativity image artifacts. Lumpectomy specimen imaging showed that strong signals can be obtained from the fatty tissue. Taken together, the results show this imaging approach with a hand-held probe has potential for detection of residual breast cancer tissue during BCS; however, more work is needed to reduce the size of the probe to fit within the surgical cavity.

Keywords: Breast cancer; Breast conserving surgery; Lumpectomy; Optoacoustic imaging; Photoacoustic imaging.